Hydrogen producing fuel processing system

Page 1 — bibliographic record

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5,705,916 1/1998 Rudbeck et all ... 322/2 R 3,469,944 9/1969 Bocard et al. ....................... 423/650 5,734,092 3/1998 Wang et al. ........................ 73/23.25 3,524,819 8/1970 Guerrieri ............................. 48/198.6 5,780,179 7/1998 Okamoto. 3,589,171 6/1971 Haley. 5,782,960 7/1998 Ogawa et al. ........................... 96/11 3,665,680 5/1972 Heuser. 5,814,112 9/1998 Elliot et al. ........................ 48/197 R 3,713,270 1/1973 Farret al.. 5,821,185 10/1998 White et al.. 3,761,382 9/1973 Hammond et al.. 5,861,137 1/1999 Edlund ................................. 423/652 3,782,904 1/1974 Fletcher. 5,888,273 3/1999 Buxbaum. 3,791,106 2/1974 Haley. 5,897,970 4/1999 Isomura et al.. 3,849,076 11/1974 Gryaznov et al. ................... 422/140 5,932,181 8/1999 Kim et al. . 3,881,891 5/1975 Goltsov et al.. 5,938,800 8/1999 Verrill et al.. 3,881.897 5/1975 Faure et al.. 5.997,594 * 12/1999 Edlund et al. ........................... 48/76 3,955,941 5/1976 Houseman et al. . 6,042,956 3/2000 Lenel. 3,972,695 8/1976 Buckley et al.. 6,045,933 4/2000 Okamoto. 3,980,452 9/1976 Krumm et al. ........................ 48/215 6,054,229 4/2000 Hsu et al. .

4,056,373 11/1977 Rubin. OTHER PUBLICATIONS 4,127,393 * 11/1978 Timmins et al. ...................... 48/213 4,132,668 1/1979 Gryaznov et al. ....................... 502/4 Amphlett, J. C., et al., “On Board Hydrogen Purification for 4,197,152 4/1980 Palty et al. -- --- ------------- --------- 252/364 Steam Reformer/PEM Fuel Cell Vehicle Power Plants,” 4,254,086 3/1981 Sanders. Energy Progress X, Proceedings ofh the 10'ti World Hydrogen 4,329,157 5/1982 Dobo et al. .............................. 95/56 f Florid 1 4,381,641 * 5/1983 Madgavkar et al. . . 60/39.06 Energy Conference, Cocoa Beach Florida, U.S.A., vol. 3, 4,400,182 8/1983 Davies et al. ...................... 48.214. A pp. 1681–1690 (Jun., 1994). 4,417.905 * 11/1983 Banks et al. ....................... 48/214 A Amphlett, J. C., et al., “Simulation of a 250 kW Diesel Fuel 4,468,235 8/1984 Hill. Processor/PEM Fuel Cell System.” Fifth Grove Fuel Cell 4,472,176 9/1984 Rubin. Symposium, Commonwealth Institute, London, U.K., p. 8 4,553.981 11/1985 Fuderer. (Sep. 22–25, 1997) 4,589,891 5/1986 Iniotakis et al.. p. s . 4,642,273 2/1987 Sasaki. Chai, M., et al., “Promotion of Methane Steam Reforming 4,650,814 3/1987 Keller ................................... 518/703 Using Ruthenium-Dispersed Microporous Alumina Mem 4,654,063 3/1987 Auvil et al. ............................ 62/624 brane Reactor,” Chemistry Letters, The Chemical Society of 4,684,581 8/1987 Struthers ................................ 429/19 Japan, pp. 41-44 (1993). 4,699,637 10/1987 Iniotakis et al.. 66 ss 4,713,234 12/1987 Weirich et al. ................... 423/648.1 Compact, Lightweight Fuel Reformer for Fuel Cells, 4,751,151 * 6/1988 Healy et al. ........................... 420, 17 Argonne National Laboratory/U.S. Department of Energy 4,781.241 11/1988 Misage et al.. (Jul., 1996).

4,788,004 11/1988 Pinto et al. Edlund, Dr. David and William Pledger, “Development of a 4,810,485 3/1989 Marianowski et al. ........... 423/648.1 Compact and Economical Steam Reformer for Fuel-Cell 4,838.897 6/1989 Amano et al. . Systems.” Fifth Grove Fuel Cell Symposium, Common

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5,205.841 so VN Emonts, B., et al., Compact Methanol Reformer Test for 5,226,928 7/1993 Makabe et al. . Fuel-Cell Powered Light-Duty Vehicles, Fifth Grove Fuel 5,326,550 7/1994 Adris et al. .......................... 423/652 Cell Symposium, Commonwealth Institute, London, U.K., 5,354,547 10/1994 Rao et al. ............................ 423/650 p. 42 (Sep. 22–25, 1997) 59. 9. isit al. . Emonts, B., et al., “Compact Methanol Reformer Test for 2- Y-12 f get al. . Fuel-Cell Powered Light-Duty Vehicles,” Fifth Grove Fuel 5,393,325 2/1995 Edlund ..................................... 95/56 5,395,425 3/1995 Brown. Cell Symposium, Commonwealth Institute, London, U.K., 5,401,589 3/1995 Palmer et al.. (no page No.), (Sep. 22-25, 1997). 5,417,051 5/1995 Ankersmit et al. . Jørgensen, S. Laegsgaard, et al., “Application of Pd-Mem 5,449,848 9/1995 Itoh. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 585/430 branes for the Production of Pure Hydrogen in

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Menzer, R., et al., “Fuel Processing in Fuel Cell Systems for English abstract of Japanese Patent No. 432150, 1992. Mobile Applications-Gasoline as Energy Carrier English abstract of Japanese Patent No. 513230, 1993. On-Bord.' Fifth Grove Fuel Cell Symposium, Common English abstract of Japanese Patent No. 514790, 1993. wealth Institute, London, U.K., (no page No.), (Sep. 22–25, 1997). English abstract of Japanese Patent No. 604070, 1994. Minet, R. G., et al., “Experimental Studies of A Ceramic English abstract of Japanese Patent No. 634540. Membrane Reactor for the Steam/Methane Reaction at Mod English abstract of Japanese Patent No. 710910, 1995. erate Temperatures (400–700°C).” Symposium on Natural English abstract of Japanese Patent No. 828793, 1996. Gas Upgrading II Presented before The Division of Petro leum Chemistry, Inc., Meeting of American Chemical Soci English abstract of Japanese Patent No. 6176779, 1994. ety, San Francisco, California, U.S.A., pp. 245–248 (Apr., English abstract of Japanese Patent No. 7057758, 1995. 1992). English abstract of Japanese Patent No. 11116202, 1999. Oertel, Michael, et al., “Steam Reforming of Natural Gas English abstract of Great Britain Patent No. 2,305,186. with Integrated Hydrogen Separation for Hydrogen Produc tion, Chemical Engineering Technology, Vol. 10, pp. Piwetz et al., “Hydrodesulfurization and Prereforming of 248-255 (1987). Logistic Fuels for Use in Fuel Cell Applications,” presented Shu, J., et al., “Catalytic Palladium-Based Membrane Reac at the 1996 Fuel Cell Seminar held Nov. 17–20, 1996 in tors: A Review, Canadian Journal of Chemical Engineering, Orlando, Florida, pp. 780–783. vol. 69, pp. 1036-1060 (Oct., 1991). Privette et al., “Status of SOFCo SOFC Technology Devel Teagan, W. P., et al., “Cost Reduction of Fuel Cells for opment,” presented at the 1996 Fuel Cell Seminar held Nov. Transportation Applications-Fuel Processing Options,” 17–20, 1996 in Orlando, Florida, pp. 206–209. Fifth Grove Fuel Cell Symposium, Commonwealth Insti tute, London, U.K. (Sep. 22–25, 1997). * cited by examiner

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HYDROGEN PRODUCING FUEL Traditionally, the process of Steam reforming and the PROCESSING SYSTEM Subsequent process of hydrogen purification occur in Sepa rate apparatus. The advantages of combining Steam reform

RELATED APPLICATIONS ing and hydrogen purification in a single device are known The present application is a continuation-in-part of and Oertel, M., et al., “Steam Reforming of Natural Gas with claims priority to U.S. patent application Ser. No. 08/951, Integrated Hydrogen Separation for Hydrogen Production”, 091, which was filed on Oct. 15, 1997, is entitled Steam Chem. Eng. Technol 10 (1987) 248-255; Marianowski, L. Reformer With Internal Hydrogen Purification, is now U.S. G., and D. K. Fleming, “Hydrogen Forming Reaction Pro Pat. No. 5,997,594, which is a continuation-in-part applica cess” U.S. Pat. No. 4,810,485, Mar. 7, 1989). An integrated tion of U.S. patent application Ser. No. 08/741,057, filed Steam reforming and hydrogen purification device should Oct. 30, 1996, which is now U.S. Pat. No. 5,861,137, and the provide a more compact device operating at lower tempera disclosure of which is hereby incorporated by reference. tures not limited by the normal equilibrium limitations. This application also is a continuation-in-part of and claims Unfortunately, Such a device has yet to be reduced to priority to co-pending U.S. patent application Ser. No. practical design. Where theory in this art recognizes the 09/190,917, which was filed on Nov. 12, 1998, is entitled 15 advantage of combining Steam reformation and hydrogen Integrated Fuel-Cell System, and the disclosure of which is purification in a Single device, the art has yet to present a also hereby incorporated by reference. practical, i.e., economical, design. Thus, a practical integrated Steam reforming and hydro

BACKGROUND OF THE INVENTION gen purification device has not yet become available. The The present invention relates generally to energy Subject matter of the present invention provides a practical conversion, and particularly to a process and apparatus for device. combined Steam reforming and hydrogen purification production of purified hydrogen by Steam reforming.

Purified hydrogen is an important fuel Source for many SUMMARY OF THE INVENTION energy conversion devices. For example, fuel cells use 25 A process for producing hydrogen containing concentra purified hydrogen and an oxidant to produce an electrical tions of carbon monoxide and carbon dioxide below a given potential. A process known as Steam reforming produces by level begins by reacting an alcohol vapor (Such as methanol) chemical reaction hydrogen and certain byproducts or impu or a hydrocarbon vapor (Such as propane) and Steam to rities. A Subsequent purification proceSS removes the unde produce product hydrogen, carbon monoxide, and carbon Sirable impurities to provide hydrogen Sufficiently purified dioxide. The reacting Step occurs in the vicinity of, or for application to a fuel cell. immediately preceding, a hydrogen-permeable and Under Steam reforming, one reacts Steam and alcohol, hydrogen-Selective membrane and the product hydrogen (methanol or ethanol) or a hydrocarbon (such as methane or permeates the membrane. A methanation catalyst bed lies at gasoline or propane), over a catalyst. Steam reforming the permeate Side of the membrane and converts any carbon requires elevated temperature, e.g., between 250 degrees 35 monoxide and carbon dioxide which passes through the centigrade and 800 degrees centigrade, and produces pri membrane to methane, thereby yielding a product hydrogen marily hydrogen and carbon dioxide. Some trace quantities Stream with concentrations of carbon monoxide and carbon of unreacted reactants and trace quantities of byproducts dioxide that are below acceptable thresholds. Optionally, Such as carbon monoxide also result from Steam reforming. reforming catalyst may also lie at the permeate Side of the Trace quantities of carbon monoxide, certain concentra 40 membrane along with the methanation catalyst to convert to tions of carbon dioxide, and in Some cases unsaturated product hydrogen any unreacted alcohol or hydrocarbon hydrocarbons and alcohols will poison a fuel cell. Carbon feed that passes through the membrane. Product hydrogen is monoxide adsorbs onto the platinum catalyst of the fuel cell then withdrawn from the methanation catalyst bed. and inhibits operation of the fuel cell, i.e., reduces the power A Steam reformer, also referred to as a fuel processor, output of the fuel cell. To a lesser degree, carbon dioxide and 45 according to the present invention includes a reforming bed other unsaturated hydrocarbons and alcohols have the same that receives and reacts a mixture of alcohol or hydrocarbon result. All impurities to Some extent reduce by dilution the Vapor and Steam to produce hydrogen and by product gases. partial pressure of hydrogen in the fuel cell and increase the The gases are then passed through a hydrogen-permeable mass transfer resistance for hydrogen to diffuse to the and hydrogen Selective membrane. On the permeate Side of platinum catalyst, and thereby reduce power output of the 50 the membrane, a methanation catalyst converts carbon mon fuel cell. Thus, fuel cells require an appropriate fuel input, oxide and carbon dioxide to methane. i.e., purified hydrogen with no additional elements contrib Many other features of the present invention will become uting to a loSS in fuel cell efficiency. manifest to those versed in the art upon making reference to Traditionally, hydrogen purification attempts to always the detailed description which follows and the accompany maximize harvest of hydrogen from the reforming process. 55 ing drawings in which preferred embodiments incorporating To maximize the amount of hydrogen obtained, a relatively the principles of this invention are disclosed as illustrative expensive device, e.g., a thick and high quality palladium examples only.

membrane, Serves as a hydrogen-permeable and hydrogen BRIEF DESCRIPTION OF THE DRAWINGS selective membrane Ledjeff-Hey, K., V. Formanski, Th.

Kalk, and J. Roes, “Compact Hydrogen Production Systems 60 For a better understanding of the invention, and to show for Solid Polymer Fuel Cells' presented at the Fifth Grove how the same may be carried into effect, reference will now Fuel Cell Symposium, Sep. 22-25, 1997). Such thick, high be made, by way of example, to the accompanying drawings quality palladium alloy membranes Support maximum har in which:

Vest of hydrogen with minimal, i.e., acceptable, impurities FIG. 1 illustrates generally an energy conversion System for use in a fuel cell. Such high level of purification, 65 including a fuel cell and a steam reformer with internal however, requires significant investment in the thick, high hydrogen purification according to one form of the present quality palladium membrane. invention.

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FIG. 2 illustrates Schematically a concentric, cylindrical (reformer) 12 according to a preferred form of the present architecture for the Steam reformer with internal hydrogen invention. Reformer 12 provides at its outlet 14 purified purification of FIG. 1. hydrogen to a PEM fuel cell 16. Fuel cell 16 receives at its FIG. 3 illustrates in cross section the steam reformer with inlet 18 an oxidant from oxidant source 20. Fuel cell 16 internal hydrogen purification of FIG. 1. produces an electrical potential 22 for application to an FIG. 4 illustrates Schematically an alternate architecture electrical load 24, e.g., an electrical motor. Fuel cell 16 also for the Steam reformer under the present invention nesting includes outlets 26 and 28 serving as fuel and oxidant multiple reformer tubes within a common combustion outlets, respectively.

region. For purposes of describing operation of reformer 12, the FIG. 5 illustrates schematically and partially in cross liquid feedstock will be methanol (MeOH) and water, Section a Steam reformer with internal hydrogen purification although other alcohols or hydrocarbons may be used in according to the present invention including a modified place of methanol. Reformer 12 receives at its fuel inlet 30 combustion system distributed within the reformation preSSurized liquid methanol and water from a pressurized methanol/water source 32. As described more fully region. 15 hereafter, the pressurized mix of liquid methanol and water FIG. 6 illustrates schematically and partially in cross Vaporizes within reformer 12 and reacts with a reforming Section another embodiment of a Steam reformer with inter nal hydrogen purification according to the present invention Stream. A produce catalyst to a hydrogen Stream and a byproduct hydrogen-Selective membrane Separates the including an isolated vaporization chamber. hydrogen Stream from the byproduct Stream. The hydrogen FIG. 7 illustrates schematically a combustion system Stream passes, by pressure differential, through the mem applicable to the present invention and providing along its brane and Subsequently through a polishing catalyst to length a generally uniform temperature gradient. appear at the outlet 14 of reformer 12. FIG. 8 illustrates the temperature gradient of the combus While traditional reforming technology allows a high tion system of FIG. 7 as compared to a conventional percentage of hydrogen produced to be taken acroSS a temperature gradient. 25

Selective membrane, the proceSS and apparatus of the present

FIG. 9 illustrates another form of steam reformer with invention takes less than a maximum available amount of internal hydrogen purification under the present invention hydrogen across the Selective membrane. The present inven using plate membrane elements. tion thereby allows use of a lesser-grade and, therefore, leSS FIG. 10 illustrates in exploded view a plate membrane expensive Selective membrane. In addition, because leSS module of the steam reformer of FIG. 9 including membrane than the maximum amount of hydrogen is separated as a envelope plates. product Stream, the required membrane area is reduced FIG. 11 illustrates in exploded view a membrane envelope portionthis under aspect of the present invention. The remaining of hydrogen enters the byproduct stream, mixes with plate of FIG. 10.

air provided at inlet 34 by air blower 36, and reacts with a

FIGS. 12-17 show membrane components for a tubular 35 combustion metal membrane module and assembly Steps in the produc temperaturescatalyst needed within reformer 12 to Support elevated for Steam reforming within reformer tion of a tubular membrane module using manufacturing 12. Reformer 12 thereby uses the byproduct stream, includ StepS according to the present invention. ing a Selected amount of hydrogen remaining therein, as a FIG. 18 illustrates in perspective, and partially broken fuel source for its combustion process. No additional fuel away, another embodiment of a Steam reformer according to 40 Source is applied to reformer 12 to Support combustion. the present invention including an isolated vaporization Reformer 12 also includes a plurality of combustion exhaust chamber and a plate-form membrane module. ports 38 releasing combustion byproducts. FIG. 19 illustrates the Steam reformer of FIG. 18 in The optimum amount of hydrogen to recover as a product Section. Stream is calculated from the heating value (enthalpy of

FIGS. 20 and 21 show components of the membrane combustion) of hydrogen. Sufficient hydrogen must be Sup module for the Steam reformer of FIGS. 18 and 19. plied in the byproduct Stream to the catalytic combustion FIG. 22 illustrates a component stack for the membrane region So that the heat of combustion exceeds the total heat module of the steam reformer of FIGS. 18 and 19 providing requirement of the reformer. The total heat requirement of a Series feed gas flow arrangement. 50 the reformer (AH) is given by

FIG. 23 illustrates a component stack for the membrane ap module of the steam reformer of FIGS. 18 and 19 providing a parallel feed gas flow arrangement. where AH, is the enthalpy of the reforming reactions; FIG. 24 illustrates a component stack for the membrane AH, is the enthalpy of vaporization of the liquid feed module of the steam reformer of FIGS. 18 and 19 incorpo 55 stock; AH is the enthalpy required to heat the vaporized rating an exhaust plate for internal heating of the membrane feed Stock to the reforming temperature; and AH is the module. heat lost to the Surrounding environment. Heat loSS from the FIG.25 illustrates in cross section another embodiment of reformer is minimized (and reduced to a negligible degree) a Steam reformer according to the present invention. with adequate insulation.

60 In the case of Steam reforming methanol according to the

FIG. 26 illustrates in cross section a variation of the following reaction Stoichiometry reformer of FIG. 25.

DETAILED DESCRIPTION OF THE

INVENTION where 8.4gmole methanol and 8.4gmole water are required 65 to yield sufficient hydrogen (21 std. ft) to generate about 1

FIG. 1 shows an energy conversion System 10 employing kW. ASSuming no heat loss and no heat exchange (between a Steam reformer with internal hydrogen purification discharged hot Streams and the relatively cold feed Stock

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S 6 stream) AH is 300 kcal. Since the heat of combustion for use of a delicate structure Such as thin membrane tube 54. hydrogen is 57.8 kcal/gmole, approximately 5.2 gmoles of Under conventional practice, a thick palladium alloy mem hydrogen (4.3 std. ft) must be combusted to provide the brane can be brazed because it can withstand the high required 300 kcal of heat for steam reforming sufficient temperatures and liquid phase aspects of brazing. A thin methanol to generate 1 kW. So, 70% to 80% of the palladium alloy membrane, as proposed herein however, hydrogen produced in the reformer is recovered as a product cannot be brazed under conventional methods because the stream and the remaining 20% to 30% of the hydrogen is elevated temperature and liquid brazing alloy destroy Such passed to the catalytic combustor in the byproduct Stream to thin palladium material. A thin membrane tube 54 could, provide a fuel Stream with Sufficient heating value to meet under conventional practice for example, attach to end caps the heating requirements (AH) of the reformer. 104 and establish a gas-tight Seal by use of gaskets and FIG. 2 illustrates schematically the concentric cylindrical Suitable Support Structures. AS discussed more fully architecture of steam reformer 12. In FIG. 2, reformer 12 hereafter, under the present invention a thin palladium alloy includes in concentric relation an outermost metal tube 50, membrane, e.g., tube 54, attaches to end caps 104 by first an inner metal tube 52, a hydrogen-Selective membrane tube attaching a foil (not shown in FIG. 3), e.g., a copper or nickel 54, and an innermost metal tube 56. Tubes 50, 52, 54, and 15 foil, to the ends of tube 54 by ultrasonic welding and then 56 are of Successively Smaller diameter and arranged in brazing the foil-wrapped ends of tube 54 to end caps 104. concentric relation to one another. An annular combustion Hydrogen stream 103 travels within transport region 64 region 60 exists in the space within tube 50 but external of toward and into the open end 56a of tube 56. Hydrogen tube 52. An annular reforming region 62 exists within tube Stream 103 includes Some impurities, e.g., carbon monoxide, 52 but external of membrane tube 54. An annular hydrogen carbon dioxide and unreacted methanol and water vapor, transport region 64 exists within membrane tube 54, but also traveling along transport region 64 and into innermost external of tube 56. A cylindrical polishing region 66 resides tube 56 at its open end 56a. All of hydrogen stream 103 within the metal tube 56. enters the open end 56a of innermost tube 56. FIG. 3 illustrates in cross section the steam reformer 12. Within tube 56 a polishing catalyst 110 reacts with In FIG. 3, outermost metal tube 50, a generally closed-end 25 impurities in the hydrogen Stream 103 passing therethrough. tubular structure, receives at one end via inlet 34 an air Metal gauze 112 downstream from catalyst 110 holds cata Supply and releases at combustion ports 38 combustion lyst 110 within tube 56. Polishing catalyst 110 (e.g., BASF byproducts. Within combustion region 60, a combustion catalyst G1-80 or ICI catalyst 23-1) reacts with certain catalyst 100 resides near air inlet 34. Alternatively, combus impurities remaining in hydrogen Stream 103, e.g., as much tion catalyst 100 may be arranged as a plurality of bands as 1% of carbon monoxide and carbon dioxide, and converts spaced at intervals within combustion region 60. Suitable Such impurities to innocuous byproducts, e.g., methane. combustion catalyst materials include platinum Supported Stream 103 of purified hydrogen and, now innocuous, on alumina or other inert and thermally-stable ceramic. Inlet byproducts passes through metal gauze 112 and exits 30, carrying the pressurized mix of methanol and water, reformer 12 at the outlet 14, i.e., at the opposite end 56b of passes through the end wall 50a of tube 50 and forms a coil 35 tube 56.

30a wrapping about the innermost metal tube 56 within the Polishing catalyst 110 may be Several Separate catalysts combustion region 60, although metal tube 56 need not within tube 56. In order to deal with carbon monoxide and necessarily pass through the axis of coil 30a. The distal end carbon dioxide impurities, one uses a methanation catalyst. of coil 30a passes through the closed end 52a of tube 52 and The process of methanation, i.e., reacting carbon monoxide opens into the reforming region 62. The pressurized mix of 40 or carbon dioxide with hydrogen to yield methane as shown liquid methanol and water entering coil 30a vaporizes at the below, is well known.

elevated temperatures of combustion region 60 and enters the reforming region 62 as vapor.

Within reforming region 62 a reforming catalyst 102 (e.g.,

BASF catalyst K3-110 or ICI catalyst 52-8) reacts with the 45

Vaporized mix of methanol and water to produce hydrogen Methanation provides an acceptable polishing Step in the vicinity of the membrane tube 54. Membrane tube 54 because methane is considered relatively inert or innocuous is composed of one of a variety of hydrogen-permeable and to the fuel cell 16 (FIG. 1) whereas carbon dioxide and hydrogen-Selective materials including ceramics, carbon, carbon monoxide are poisonous to the fuel cell. and metals. Especially preferred materials for fabricating 50 If reformer 12 uses methanol in the Steam reforming Step, Said membrane tube 54 are hydrogen-permeable palladium and leaks in the membrane tube 54 allow carbon monoxide alloys, e.g., palladium alloyed with 35–45 wt % silver. Each and carbon dioxide to pass into the hydrogen Stream 103, end of membrane tube 54 is sealed by a metal cap 104. A Some unreacted methanol and water vapor may exist in the metal gauze 106 within the reforming region 62 Surrounds hydrogen stream 103. To convert Such unreacted methanol each cap 104 and maintains the catalyst 102 within region 62 55 into a harmless byproduct prior to entering the fuel cell 16 and in the vicinity of membrane tube 54. A hydrogen stream (FIG. 1), a reforming catalyst which is a low temperature 103 migrates by pressure differential through membrane copper/zinc shift catalyst, is placed through a portion (e.g., tube 54 and into hydrogen transport region 64. A thin one-fourth to one-third) of the polishing catalyst bed, i.e., membrane tube 54 requires Support against deformation innermost tube 56, followed downstream by a methanation under the preSSure differential between reforming region 62 60 catalyst.

and hydrogen transport region 64. For this purpose, a tension The predominant chemical reaction for Steam reforming spring 101 Supports membrane tube 54 from within while methanol is shown below.

allowing hydrogen Stream 103 to pass by, into and along transport region 64.

Because a thin palladium alloy membrane may be used 65 Returning to reforming region 62, Steam reforming under the present invention, Special construction methods byproduct stream 105 moves toward closed end 52b of tube have been developed under the present invention to make 52 and through critical orifice 120 serving as an outlet for

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tube 52 and discharging near air inlet 34. Optionally, deflec reformer tubes 51, i.e., each a combination of a tube 52, a tor 57 directs the flow of byproduct stream 105 and air from tube 54, and a tube 56, are arranged in spaced relation. While inlet 34 toward combustion catalyst 100. Byproduct stream not shown in FIG. 4 for purposes of clarity, reformer 12 105 thereby encounters and mixes with the air inflow 107 of would include a feedstock inlet, a product hydrogen outlet, air at inlet 34. Air inflow 107 may be preheated to enhance 5 and a combustion gas outlet. A common air inlet 34 Supplies the catalytic ignition within combustion region 60. For air to the common combustion region 60'. As may be example, an air heater 37 (FIG. 1) may be provided in series appreciated, each of reformer tubes 51 provides a byproduct along the inlet 34 to reformer 12. Alternatively, inlet 34 may stream 105 (not shown in FIG. 4) to the common combus be routed through combustion region 60 as shown Schemati tion region 60'.

cally in FIG. 3. The resulting mixture travels toward and Returning to FIG. 3, reformer 12 must be initiated to through combustion catalyst 100 and ignites thereat. The operate. Generally, the reforming region 62 must be elevated combustion byproducts then travel through combustion to approximately 150 to 200 degrees Celsius if methanol is region 60 and eventually, after heating coil 30a and ther the feedstock, or 300 to 500 degrees Celsius if hydrocarbons mally Supporting the Steam reforming process within region are the feedstock. Once the reforming process begins, the 62, exit reformer 12 at the combustion exhaust ports 38. 15 byproduct Stream 105, including by design a given amount Reformer 12 operates at a relatively lower temperature of hydrogen as combustion fuel, enters the combustion than conventional Steam reforming devices. Because region 60, encounters combustion catalyst 100, and com reformer 12 continually purifies hydrogen as it is produced, busts to thermally Support the Steam reforming process. The the Steam reforming reaction may be conducted well away combustion catalyst only needs hydrogen present (mixed from its equilibrium limitation. Although equilibrium limi with air) to ignite the byproduct stream 105. The goal in tations are generally not important in the case of Steam Starting reformer 12, therefore, is to elevate the reforming reforming methanol, they are very important in the case of region 62 to approximately 150 to 200 degrees Celsius (in Steam reforming methane (natural gas). Unreacted reactants the case of methanol reforming).

in the relatively lower temperature reforming process tend to A simple cartridge-type electric resistance heater 140, be eventually reacted due to the continuous Siphoning of 25 either inserted into the reforming catalyst 102 or, as illus hydrogen from the process. Under the present invention, the trated in FIG. 3, into the center of tube 56 initiates operation Steam reforming proceSS may be operated at approximately of reformer 12. Alternatively, a resistance heater may be 250 to 600 degrees Celsius. For methanol reforming the used to heat the methanol and water feed provided at inlet operating temperature of the reformer would be approxi 30. In either event, once the reforming catalyst 102 reaches mately 250 to 300 degrees Celsius. a sufficiently high temperature (150 to 200 degrees Celsius) To create an appropriate pressure differential at membrane the reforming reaction begins and the combustion catalyst tube 54, the liquid methanol and water should be pumped, 100 reacts with hydrogen present in byproduct stream 105. i.e., provided by Source 32, at approximately 6 to 20 At this point, the electrical resistance heater 140 can be shut atmospheres. The polishing Step should be conducted at down. A 50 to 100 watt resistance heater 140 should be approximately one to three atmospheres within polishing 35 adequate, based on conventional thermal mass calculations, region 66. The pressure within hydrogen transport region 64 to Sufficiently heat the reforming region 62 in a matter of is essentially equal to the pressure within polishing region minutes.

66. The reforming process should be operated at 6 to 20 FIG. 5 illustrates, partially and in croSS Section, an alter atmospheres to provide a Substantial pressure differential nate form of the present invention with its combustion across membrane tube 54. Critical flow orifice 120 can be 40 System distributed through the reformation region to sized to provide a preSSure drop from the reforming region improve heat transfer from the combustion process to the 62 (6 to 20 atmospheres) to one atmosphere within the reformation process. In FIG. 5, reformer 212 is a steam combustion region 60. The byproduct stream 105 thereby reformer with internal hydrogen purification receiving at its enters the combustion region 60 at approximately one atmo inlet 230 a feed Stock, e.g., methanol and water, and pro sphere. This allows operation of the air supply at inlet 34 at 45 Viding at its outlet 214 purified hydrogen for application to, approximately one atmosphere, and thereby allows use of an for example, a fuel cell (not shown in FIG. 5). As with earlier inexpensive air blower 36. embodiments of the present invention, reformer 212 leaves Dimensions for reformer 12 sufficient to feed a typical a Selected portion of hydrogen in its byproduct Stream to fuel cell 16 are relatively small. Ten liters per minute (21 Support the combustion process. Combustion byproducts cubic feet per hour) of hydrogen is Sufficient to generate one 50 exit at the exhaust port 238.

kilowatt of electrical energy in fuel cell 16. Asteam reformer Reformer 212 includes an outer metal tube 252 sealed at 12 under the present invention Sufficient to Support a one each end by end plates 253, individually 253a and 253b and kilowatt fuel cell 16 would be roughly three inches in gaskets 255, individually 255a and 255b. Bolts 257 secure diameter by 15 to 16 inches in length. To increase volumetric end plates 253 against the shoulders 252, individually, 252a production, the length of reformer 12 could be increased or 55 and 252b, at each end of tube 252. A hydrogen purification the diameter of reformer 12 could be increased. The volu module lies within and generally concentric to tube 252 and metric production rate for reformer 12 is limited primarily includes a thin palladium alloy membrane tube 254 sealed by the area of membrane 56 exposed to the reforming by end caps 304a and 304b. Alternatively, membrane tube process. Increasing the length of reformer 12 or the diameter 254 may be comprised of hydrogen-Selective and hydrogen of reformer 12 increases the exposed area of membrane tube 60 permeable materials other than palladium alloys, including 54 and thereby increases hydrogen output for reformer 12. porous carbon, porous ceramics, hydrogen-permeable met However, multiple standard-sized reformers 12 may be als other than palladium porous metals, and metal-coated employed in parallel within a common combustion Zone. porous carbon and porous ceramics and porous metals. AS FIG. 4 illustrates schematically the architecture of an may be appreciated, tube 254 and caps 304 may be Sup alternate reformer 12" with an enlarged outermost metal tube 65 ported in some fashion (not shown) within tube 252. End cap 50' defining a common combustion region 60'. Within the 304b communicates with outlet 214 through plate 253b and relatively larger combustion region 60', a plurality of the product hydrogen stream 303 emerges from outlet port

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214. A polishing catalyst bed, preferably a methanation to the surface area provided by tube 52 in reformer 12. Heat catalyst, is located at the permeate Side of membrane tube energy need not transfer into and migrate acroSS the refor 254 (not shown) as discussed earlier and shown in FIG. 3. mation region, but rather generates within the reformation Inlet 230 passes through wall 253a and couples to a region and radiates outward throughout the reformation vaporization coil 230a. Outlet 231 of coil 230a feeds region.

directly into the reformation region 262 defined as being FIG. 6 illustrates another embodiment of the present within tube 252 but external of tube 254. Also located within invention, also distributing combustion heat energy through and distributed throughout the reformation region 262 is a out the reformation region, but further providing the advan combustion coil 250. In the particular embodiment tage of isolating the vaporization process from the reforma illustrated, coil 250 surrounds in spiral fashion membrane tion process. Generally, a preferred temperature for tube 254 and extends substantially throughout the entire Vaporization of the feed Stock, e.g., 400-650 degrees Centigrade, is greater than a preferred temperature, e.g., reformation region 262. A combustion catalyst 302 lies 250-500 degrees Centigrade, for hydrogen reformation In within and either along the length of coil 250 or localized FIG. 6, Steam reformer 312 includes an outer metal tube 352 within coil 250 at or near end 250a. End 250a of coil 250 defining therein a reformation region 362. Tube 352 includes receives a fuel Stock, as described more fully hereafter, and 15 shoulders 352 at each end, individually 352a and 352b. A combustion occurs within coil 250 as the fuel stock travels vaporization module 340 attaches to shoulders 352a of tube along coil 250 and encounters the combustion catalyst 302 352. Module 340 defines a vaporization chamber 342 iso therein. Because coil 250 extends uniformly throughout the lated relative to reformation region 362. More particularly, reformation region 262 and because coil 250 provides module 340 includes a generally cylindrical barrel 344 Significant Surface area, rapid and well distributed heat having an open end 344a and a closed end 344b. An end transfer occurs from the combustion process occurring plate 346 and gasket 348 seal vaporization chamber 342, i.e., within coil 250 to the surrounding reformation region 262. close the otherwise open end 344a of barrel 344. The closed Reformation region 262 couples through wall 253b at its end 344b of barrel 344 couples to shoulders 352a of tube outlet 220 to a conduit 221. Conduit 221 carries the byprod 352. In this manner, closed end 344b together with a gasket uct stream 205, i.e., the byproduct of hydrogen reformation 25 350 seal the end of tube 352 and, thereby, seal reformation including a Selected amount of hydrogen intentionally not chamber 362. By isolating vaporization chamber 342 and taken across the membrane tube 254, to the combustion reformation chamber 362, Vaporization occurs at preferred, process. Conduit 221 delivers byproduct stream 205 to a i.e., Significantly higher, temperatures than temperatures pressure let down valve 223. Byproduct stream 205 then preferred Inlet for reformation chamber 362.

330 passes through end plate 346 and feeds into coil continues, at lowered pressure, into an intake manifold 207. 230a as located

Manifold 207 includes an air inlet 209, e.g., coupled to an air end of coil 230awithin then vaporization chamber 342. The distal pass through closed end 344b of barrel blower or to discharged air from the cathode component of 344 and feeds into reformation chamber 362. In this manner, the fuel cell (not shown in FIG. 5), and air passage way 211 vaporized feed stock, i.e., methanol and water vapor, enter carrying combustion air to a mixing region 213 at or near the region 362 and chemically interact with reformation catalyst inlet 250a of combustion coil 250. The combustion fuel 35 400 distributed throughout reformation region 362. stock as provided by the byproduct stream 205, thereby Vaporization chamber 342 includes outlets passing com mixes with the incoming combustion air in mixing region bustion exhaust along corresponding conduits 370 extending 213 and enters end 250a of combustion coil 250. Combus through combustion region 362. In this manner, the heat tion catalyst 302 within coil 250 ignites the fuel stream 205 energy of the combustion exhaust transferS through conduits and heat transfers efficiently and rapidly in well distributed 40 370 and into the reformation region 362. Again, distributing fashion into and throughout the reformation region 262. heat energy throughout and within the reformation region While a coil or spiral form of combustion system has been improves heat transfer distribution and rate. For example, illustrated, i.e., the coil 250, other shapes may be employed vaporization chamber 342 includes outlets 342a and 342b as a combustion System within the reformation region 262. passing combustion gas into corresponding conduits 370a For example, generally tubular Structures may assume a 45 and 370b. The combustion exhaust remains isolated relative variety of forms for distribution throughout reformation to the combustion region 362, but the heat energy of the region 262. AS discussed more fully hereafter, a counter combustion exhaust migrates through conduits 370 and into current combustion system as illustrated in FIG. 7 estab the combustion region 362. Conduits 370 pass through an lishes improved, i.e., uniform, heat distribution throughout end plate 353b, secured to shoulders 352b, and the combus reformation region 262. Thus, the advantage of distributing 50 tion exhaust releases to atmosphere. Heat transfer can be a combustion System throughout the reformation region 262 improved, and the degree of resistance to flow and turbu may be achieved in a variety of Specific configurations. lence along the exterior conduits 370 can be controlled by In steam reformer 12 (FIG. 3), the combustion process use of baffles 371.

occurred in a region Surrounding the reformation region, i.e., AS in previously described embodiments, reformation externally of the tube 52 (FIG. 3) thereby requiring heat 55 occurring in reformation region 362 Supports migration of transfer into and across metal tube 52. From the inner hydrogen across a tubular palladium alloy membrane 354. Surface of tube 52, heat transfer then occurred by migration Other hydrogen-permeable and hydrogen-Selective compo across the reformation region. In Steam reformer 212, Sitions tat may be used in place of palladium alloys for however, heat generated within and distributed throughout membrane 354 include porous carbon, porous ceramic, the reformation region 262, i.e., within the coil 250, better 60 hydrogen-permeable metals, porous metals, and metal transferS more rapidly throughout the reformation region coated porous ceramicS and porous carbon and porous 262. In essence, the combustion process has been brought metal. Tubular membrane 354, sealed at each end by means into and distributed throughout the reformation region 262. of end caps 304, feeds the product hydrogen stream 303 at Heat transfer improves because the flow of reformation the outlet 314 of reformer 312. A polishing catalyst bed (not gasses passes directly over and around coil 250. Generally, 65 shown) is located at the permeate side of membrane 354 as coil 250 provides Significantly greater Surface area for heat shown in FIG. 3. A preferred polishing catalyst is a nation transfer between combustion and reformation as compared catalyst.

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By intentionally not recovering all hydrogen available in Generally, a significant temperature gradient exists along the reformation region 362, the remaining hydrogen Sweeps a combustion catalyst bed, the hottest potion being where the away in the byproduct stream 305 and provides a fuel stock fuel gas and combustion air first encounter the combustion for the vaporization module 340. More particularly, refor catalyst or igniter device. Such significant temperature gra mation region 362 couples to a conduit 321 passing through dient can be undesirable, especially when applying the heat end plate 353b. Conduit 321 carries the byproduct stream energy to a reformation process most desirably conducted at 305, including a Selected amount of hydrogen remaining uniform the throughout Under the present invention, com therein as fuel Stock. Conduit 321 passes through a preSSure bustor 450 provides a more uniform temperature gradient let down valve 323 and provides the reduced-pressure fuel along its length as compared to a conventional combustion Stock flow 305" to an inlet manifold 307. Inlet manifold 307 bed. The hottest gasses within combustor 450, i.e., near operates in similar fashion to the inlet manifold 207 of FIG. manifold 452, release heat energy through tube 430 and into 5, i.e., receiving combustion air and promoting mixing of the the coolest gasses within combustor 450, i.e., near exhaust combustion air and reduced-pressure byproduct stream 305'. port 435. By thermally coupling the hottest portion of the As the combined combustion air and steam 305 intermix at gasses with the coolest portion of the gasses a more uniform the mixing region 313, an igniter 319 triggerS combustion 15 overall temperature gradient exists along combustor 450. thereof. Igniter 319 may be a variety of devices, e.g., glow FIG. 8 illustrates a relationship between the length L of a plug, Spark plug, catalyst, and the like. In the preferred form combustion bed (X axis) and temperature There along (y of the reformer 312, however, a high Voltage Spark ignition axis). Curve 460 in FIG. 8 illustrates substantially higher or possibly a glow plug is considered preferred as igniter 319 temperatures at the beginning of a conventional combustion for long term reliability and ease of replacement. bed and a significant drop in temperature throughout the In addition to isolation of vaporization, reformer 312 also conventional combustion bed. Curve 462, however, illus provides the advantage of a preferred low pressure drop trates the more uniform, i.e., more flat, temperature gradient between the initiation of combustion and exhaust from the obtained by use of combustor device 450. More particularly, combustion region. The architecture of reformer 312 pro a shallow and fairly level curve 462 indicates a uniform vides a lower pressure combustion process because conduits 25 temperature along the length of combustor 450. 370 are generally straight conduits offering reduced and Accordingly, combustor 450 provides a more uniform dis controlled resistance to the flow of combustion exhaust persal of heat energy into a reformation region. gasses. With a lower pressure combustion process, combus While illustrated as a generally straight device in FIG. 7, tion air, e.g., such as is provided at inlet 309 of intake it will be understood that the double-walled architecture of manifold is 307, may be provided by a relatively lower the combustion device 450 may be formed in alternate pressure and relatively less expensive air blower (not shown shapes, e.g., Spiral, and applied to the various embodiments in FIG. 6). of the present invention as a combustion System. FIG. 7 illustrates Schematically an alternate combustion In addition to alternate combustion and vaporization System applicable to the various embodiments of the present features, alternative methods of hydrogen purification may invention. In FIG. 7, a double-walled counter current com 35 be employed in a Steam reformer under the present inven bustor 450 includes an inlet manifold 452 receiving a tion. In addition to tubular and concentric-tubular byproduct stream 421 and an air stream 423. Byproduct 421 architectures, planar membrane Structures may also be is taken from a reformation process as a byproduct but employed in a Steam reformer with internal hydrogen puri includes a Selected amount of hydrogen intentionally left fication.

therein as a fuel stock for combustion Byproduct stream 421 40 FIG. 9 illustrates schematically a further embodiment of travels along an inner conduit 425 and exits conduit 425 in a Steam reformer with internal hydrogen purification accord a mixing region 413. Air Stream 423 travels along manifold ing to the present invention and using planar membrane 452, generally Surrounding and parallel to inner conduit 425 structures. In FIG. 9, reformer 512 includes an outer metal and encounters byproduct Stream 421 in mixing region 413. tube 550 having shoulders 550a and 550b at each open end Mixing region 413 comprises an inner tube 430 carrying 45 thereof. Within tube 550, a metal reforming catalyst tube therealong the mixture of combustion air, i.e., air Stream 423 552 and a metal polishing catalyst tube 556 lie in generally and fuel gas, i.e., byproduct stream 421. Tube 430 is closed parallel relation along the length of tube 550. As may be at one end, i.e., end 430a forming a portion of manifold 452. appreciated, however, a variety of geometric configurations The open end 430b of tube 430, however, releases mixed and relationships between tubes 552 and 556 may be fuel gas and combustion air into an outer mixing region 415. 50 employed. Reforming catalyst tube 552 contains a reforming Outer mixing region 415 is defined by an outer tube 432. catalyst 502 and establishes a reformation region 562. Tube 432 is closed at each of its ends 432a and 432b with Similarly, polishing catalyst tube 556 contains a polishing manifold 452 passing through end 432a. A combustion catalyst 504 and establishes a polishing region 564. An end catalyst 440 is distributed throughout regions 413 and 415. plate 590 and gasket 592 couple to shoulder 550a and seal Alternately, combustion catalyst 440 may be localized 55 tube 550. Inlet port 530 carries a liquid feed stock, e.g., within tube 430 at or near mixing region 413. methanol and water, through end plate 590 and into vapor The highest temperature combustion occurs when the ization coil 530a. In the particular embodiment illustrated, mixture of fuel gas and combustion air first encounter coil 530 wraps about one end of tube 552 and sits near the catalyst 440, i.e., at the outlet of manifold 452. As the gas combustion exhaust port 538 provided in end plate 590. mixture continues along tube 430 and encounters catalyst 60 Vaporization coil 530a couples to end 552a of tube 552 440 therealong, continued combustion occurs but generally whereby vaporized feed stock exits coil 530a and enters at progressively lower temperatures. AS the gas mixture reformation region 562.

continues out of tube 430, at its open end 430b, it reverses A plate membrane module 554 couples to shoulder 550b direction and travels back along tube 432 and encounters and seals end 550b of tube 550 to complete a combustion more catalyst 400. AS a result, beat energy is produced along 65 region 560 within tube 550, but external of tubes 552 and the length of tubes 430 and 432 and exhaust gasses exit at 556. Plate membrane module 554 couples to tube 552 to the exhaust port 435. receive a reformate-rich gas flow 501, couples to conduit

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529 to provide a product or hydrogen stream 503, and Each membrane envelope plate 590 includes ports posi couples to conduit 521 to provide a byproduct stream 505 as tioned in locations corresponding to ports 592a, 594a, 596a, fuel stock to support combustion in region 560. More than and 598a of end plate 554a. When stacked and operating as one tube 552 may be used. Byproduct stream 505, as in the plate membrane module 554, these various ports align earlier-described embodiments of the present invention, and provide conduits to and from the filtration process intentionally includes a given amount of hydrogen not taken executed by module 554. Each of plates 590a–590c include from the reformation proceSS and applied to the combustion a product port 598, individually 598b-598d. Ports process. Conduit 521 carries byproduct steam 505 from 598a–598d align and cooperate to provide a conduit for plate membrane module 554 through a pressure let down product stream 503 out of module 554 and into conduit 529. valve 523 and into combustion region 560 at the inlet port 1O AS will be explained more fully hereafter, the product, i.e., 525 thereof. Adjacent fuel inlet port 525, an air inlet port 528 hydrogen, enters ports 598b-598d laterally within the cor admits air, e.g., forced by blower (not shown), into com responding membrane envelope plate 590. Each of mem bustion region 560. Alternatively, a manifold, as in earlier brane envelope plates 590a–590c include also a port 596, described embodiments of the present invention, may be individually 596b-596d, aligned with outlet port 596a of used to admit air and byproduct stream 505 into combustion 15 end plate 554a. Ports 596a–596d also carry product stream region 560. As the byproduct stream 505 enters region 560, 503 away from plate membrane envelopes 590 and into and intermixes with the combustion air at port 528, it conduit 529. As with ports 598b–598d, ports 596b–596d continues past an igniter 575. Igniter 575 initiates combus receive the hydrogen stream 503 laterally from within the tion of the mixture of byproduct stream 505 and combustion corresponding membrane envelope plate 590. air thereby Supporting a combustion process within com Ports 592b–592d align with port 592a of end plate 554 bustion region 560. AS may be appreciated, heat developed and hereby provide a conduit for introduction of the in this combustion proceSS Support Vaporization of feed hydrogen-rich reformate flow 501 from tube 552 and into stock in the vaporization coil 530a and thereby provides membrane envelope plates 590. Each of plates 590a–590c Vaporized gasses to the reformation region 562. Heat from include a byproduct port 594b–594d. Ports 594b–594d align combustion in region 560 also serves to directly heat the 25 with port 594a of end plate 554a to provide a conduit for the reforming region 562 and to heat the polishing region 564. byproduct stream 505 away from membrane envelope plates Conduit 529 carries the product (hydrogen) stream 503 590. Forcing the hydrogen-rich reformate flow 501 into port into end 556b of polishing catalyst tube 556. More than one 592a produces the byproduct flow 505 at port 594a for conduit 529 and more than one tube 556 may be used. application to the comb on process within combustion Product stream 503 passes through the polishing region 564, region 560 and produces the product stream 503 for appli where undesirable elements are neutralized, and the final cation to the polishing region 564. purified hydrogen product passes from the end 556a of tube Each of the membrane envelope plates 590 itself includes 556 and out the outlet port 514. For example, when the a stack of individual plate elements. FIG. 11 illustrates in polishing catalyst 504 is a methanation catalyst, carbon exploded view the set of plate elements found in each of the monoxide and carbon dioxide present in product steam 503 35 membrane envelope plates 590. In FIG. 11, each of the plate are converted to methane as described previously. elements include ports establishing communication through FIG. 10 illustrates in exploded view the plate membrane the membrane envelope 590 as described above in connec module 554 and its relationship to tube 552 and to conduits tion with FIG. 10. Some of these ports, however, are “open” 521 and 529. Plate membrane module 554 includes end laterally into the corresponding plate element and thereby plates 554a and 554b. A series of membrane envelope plates 40 provide lateral access to portions of module 554. 590 stack between end plates 554. In the particular embodi Each membrane envelope plate 590 includes a left spacer ment of the invention illustrated in FIG. 10, three Such plate 600 and right spacer plate 602 as the outer most plates membrane envelope plates 590, individually 590a–590c, in the stack. Generally, each of spacer plates 600 and 602 are stack between end plates 554. End plates 554a and 554b and “frame” sutures defining an inner open region 604. Each membrane envelope plates 590 are all generally rectangular 45 inner open region 604 couples laterally to ports 592 and 594. and have corresponding dimensions. Other geometries, Such Port 592 thereby admits flow 501 into open region 604 and as circular, may be used rather than the rectangular geometry port 594 thereby carries byproduct stream 505 out of open shown. In other words, plates 554a–554b and 590a–590c region 604. Ports 596 and 598, however, are closed relative Stack like a deck of cards and couple together, e.g. by to open region 604 thereby isolating the product stream 503. brazing, to form module 554. End plate 554b is a solid 50 Each membrane envelope plate 590 also includes a left planar structure. End plate 554a, however, includes inlet and membrane plate 606 and a right membrane plate 608, each outlet ports for coupling to other portions of reformer 512 adjacent and interior to a corresponding one of plates 600 (shown in FIG. 9). In particular, reformation catalyst tube and 602. Membrane plates 606 and 608 each include as a 552 couples to a reformate-rich inlet port 592a to receive the central portion thereof a palladium alloy membrane 610 products of reformation, i.e., to receive the reformate rich 55 secured to an outer metal frame 607. In plates 606 and 608, flow 501. Conduit 521 couples to a reformate-depleted all of the ports 592, 594,596, and 598 are closed relative to outlet port 594a to take from module 554 the byproduct the palladium alloy membrane 610. Each palladium alloy stream 505. In the particular embodiment illustrated, module membrane 610 lies adjacent to a corresponding one of open 554 has two product outlet ports, individually 596a and regions 604, i.e., adjacent to the hydrogen-rich reformate 598a, providing product stream 503. However, only one 60 flow 501 arriving by way of port 592. This provides unity for product outlet port may be used in Some embodiments. hydrogen to pass through the palladium alloy membrane 610 Conduit 529, shown twice in FIG. 10, couples to ports 596a of the adjacent membrane plate 606. The remaining gasses, and 598a to collect the product stream 503 therefrom All of i.e., the byproduct stream 505, leave open region 604 the ports 592a, 594a, 596a, and 598a, need not be located on through port 594.

end plate 554a. Rather, one or more of the ports may be 65 A screen plate 609 lies intermediate membrane plates 606 located on end plate 554b as desired or necessary in a planar and 608, i.e., on the interior or permeate side of each of configuration. membranes 610. Screen plate 609 includes an outer frame

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611 and carries in a central region thereof a screen 612. Ports membranes 610 carrying a foil may be attached by brazing 592 and 594 are closed relative to the central region of the foil to the surrounding frame 607 of plates 606 and 608. screen plate 609, thereby isolating the byproduct stream 505 When applied to joining metals, ultraSonic welding Strips and the reformate-rich flow 501 from the product stream away and cleans the metal Surfaces to Such extent that 503. Ports 596 and 598 are open to the interior region of contact between Such ultra-clean metals results in joining by plate Screen 609 carrying Screen 612. Hydrogen, having Solid State intermetallic diffusion. The ultraSonic action passed through the adjoining membranes 610, travels along Scrubbing the mating Surfaces of the materials may be done and through screen 612 to the ports 596 and 598 and under pressure Such as 20 to 60 psi. Once these materials eventually to conduit 529 as the product stream 503. contact, the metal atoms diffuse together and thereby estab As the hydrogen-rich reformate flow 501 enters port 592a lish a gas tight Seal. Important to note, ultraSonic welding and forces its flow against membranes 610, hydrogen passes does not require a liquid phase and when properly executed therethrough as the product stream 503 and along ports 596 does not present opportunity for deterioration of a thin and 598. The byproduct steam 505 diverts at the membranes palladium alloy membrane. Because of the relatively low 610 and travels along port 594 to conduit 521. temperature requirements of ultrasonic welding, very little A variety of methods, including brazing, gasketing, and 15 warping of material occurs. Accordingly, ultraSonic welding welding, may be used, individually or in combination, to is particularly well Suited for establishing a gas tight Seal achieve gas-tight seals between plates 600, 602, 606, 608, relative to an ultra thin palladium alloy membrane. and 609, as well as between membrane envelopes 590a-c. Under the disclosed embodiment of the present invention, Screen 612 not only provides a flow path for the product ultraSonic welding is used to attach a copper or nickel alloy flow 503, but also bears the pressure differential applied to foil to the surface of the thin palladium alloy membrane. membranes 610 to force hydrogen, i.e., product stream 503, Once this additional copper or nickel alloy layer has been across membranes 610. While illustrated only as a screen ached it is brazed or welded to an adjoining material e.g., structure in FIG. 11, it will be understood with a variety of end caps 304 or frames 607.

Structures may be used within an open region of Screen plate FIGS. 12-16 show the components and manufacturing 609 to provide the Support function against pressure applied 25 StepS used in constructing a membrane module, e.g., Such as to membranes 610 and to provide a flow for product stream illustrated in FIGS. 1, 5, and 6 generally described as a 503. To the extent that palladium alloy membranes 610 are tubular palladium alloy Structure Supported with end caps. better Supped by an appropriate Structure, e.g., Screen 612, FIGS. 12 and 13 illustrate a palladium alloy foil 702 and a thinner and less expensive palladium alloy membranes 610 copper or nickel frame 706 joined, respectively, in prepara may be employed. Alterative materials to Screen 612 include tion for joining by ultraSonic welding as illustrated in FIG. porous ceramics, porous carbon, porous metal, ceramic 14. FIG. 15 shows the combined palladium alloy foil and foam carbon foam, and metal foam. copper or nickel frame assembly 720 rolled into a tubular AS discussed throughout this specification, use of thin, Structure and again joined by ultraSonic Welding to maintain leSS expensive palladium alloy membranes significantly the tubular Structure. In this configuration, the end portion of reduces the cost of a Steam reformer under the present 35 the tubular assembly bears exposed Sections of copper or invention. While it is recognized that use of such thin nickel material. The end caps are then brazed directly to this palladium alloy membranes will result in Some contaminants exposed portion of copper or nickel frame to complete the passing into the product Stream 503, Subsequent purification gas-tight Structure.

StepS may be taken, e.g., Such as illustrated in Several With reference to FIGS. 12-16, a tubular hydrogen embodiments of the present invention. 40 permeable metal membrane 700 (FIG. 17) was prepared by Manufacturing Steps taken in manipulation of the thin the following general method of construction. Both Pd-40Cu palladium alloy membranes, particularly in establishing a and Pd-25Ag foil (nominally 25 micron thick) were used as gas-tight Seal relative to Such membranes, must take into the hydrogen-permeable membrane 702 (shown individually account the delicate nature of Such thin palladium alloy in FIG. 12). A tension spring 704 (FIGS. 15-17), composed membranes. In particular, conventional welding or brazing 45 of either carbon Steel or StainleSS Steel, was used as Support manufacturing Steps, i.e., Steps including a liquid-phase, within the tubular membrane structure 700. cannot by applied to extremely thin (typically <50 microns) The first step was to join the palladium-alloy foil 702 to palladium alloy membranes. In particular, when liquid phase the copper foil frame 706 (nominally 50 microns to 125 material contacts the thin palladium alloy membrane it microns thick) as shown in FIG. 14. The palladium-alloy foil dissolves and melts the membrane and, due to the extremely 50 702 was typically 8.9 cm wide by 26.4 cm long, and the thin nature of the membrane, cannot Serve as an acceptable copper foil frame 706 was typically 10.2 cm wide by 27.9 manufacturing Step. There are a variety of ways to establish cm long with a cut out center, equally Spaced from all four a gas-tight Seal relative to a thin palladium alloy membrane, Sides, approximately 7.6 cm wide by 24.1 cm long. This however, the Subject matter of the present invention pro provided a 0.6 cm overlap 710 (FIG. 14) between the poses a particular method of manufacturing to achieve a gas 55 palladium-alloy foil 702 and the copper foil frame 706 as tight Seal of a thin palladium alloy membrane without foil 702 occupied the cut out center of frame 706. causing Significant damage to, i.e., leaks in, the palladium Ultrasonic welding was used to establish peripheral gas alloy membrane. tight seals 712 between the palladium-alloy foil 702 and the Under the present invention, a palladium alloy membrane copper foil frame 706 at all four edges of the palladium-alloy may be attached and form a gas tight Seal relative to an 60 foil 702. An Amtech (Shelton, Conn.) Ultraseam Model 40 adjoining structure by means of an intermediate foil attached welder was used. This welder operates at 40 kHz and by ultraSonic welding. The method of manufacture proposed delivers up to about 750 W of power to the ultrasonic herein may be applied to the tubular form of membrane transducer. Both the horn (connected to the ultraSonic modules, e.g., Such as shown in FIG. 3, or to plate form transducer) and the anvil rotate at a rate Selected by the membrane structures such as shown in FIG. 11. Membrane 65 operator during normal operation of the welder. Welding is tube 54 may then be coupled by brazing the foil to end caps accomplished by placing metal between the horn and anvil 304. In the plate membrane form of the present invention, and applying power to the ultraSonic transducer.

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The horn and anvil for the ultrasonic welder are circular, reformation region 862. A reformation product stream 801 7.0 cm diameter, with a bearing Surface Strip about 0.2 cm exits reformation region 862 at the outlet conduit 852. wide and finished to a Surface roughneSS equivalent to an Conduit 852 delivers product stream 801 to membrane EDM #3 finish. The horn and anvil were hard coated with module 854. Module 854 separates stream 801 into a titanium nitride. Typical welding parameters are: 40% full byproduct stream 805 and a hydrogen-rich stream 803. power to the transducer, 40 psig applied preSSure between The hydrogen-depleted reformate byproduct stream 805 the horn and the anvil, 4 rpm rotation rate for the horn and travels along conduit 821 from membrane module 854 to a anvil, and the horn “floating” on the foil pieces to be welded pressure let down valve 823 (schematically illustrated in (i.e., no preset separation between the horn and anvil). To FIG. 19) and then to a manifold 807. Manifold 807 operates ensure that the metals are bonded during the welding in similar fashion to manifold 207 of reformer 212 (FIG. 5). process, the adjoining metal Surfaces should be cleaned of More particularly, manifold 807 introduces an air supply residues Such as oxidation, grease and oils, dirt etc. It is also taken from inlet 809, e.g., from a forced air supply, and considered beneficial if the palladium-alloy membrane foil intermixes it with stream 805 at a mixing region 813. An 702 and the copper foil frame 706 are annealed prior to igniter 819 ignites the intermixed air and stream 805 and the welding, Since Soft metals are more reliably joined by 15 resulting combustion elevates temperatures within the ultraSonic welding than are hard metals. vaporization chamber 820. As in earlier described embodi After welding the palladium-alloy foil 702 to the copper ments of the present invention, stream 805 includes by foil frame 706 to establish the membrane assembly 720 as design a certain amount of hydrogen not taken across the shown in FIG. 14, the welded seals 712 were examined for palladium alloy membranes of module 854. Stream 805 leaks by a Standard dye penetration test. If no leaks were thereby serves as a fuel source for combustion within found, membrane assembly 720 was cleaned of excess dye vaporization chamber 820.

and then wrapped, as illustrated in FIG. 15, lengthwise Exhaust ports 842 carry the combustion byproducts from around a 2.8 cm (outside diameter) tension spring 704, 27.9 chamber 820 through combustion conduits 843 and out cm long and made from either Stainless Steel or carbon Steel exhaust ports 838, shown more clearly in FIG. 19. Conduits wire nominally 0.25 cm diameter. The overlap 722 of 25 843, however, pass through the reformation chamber 842 opposite edges of assembly 720 was then joined by ultra and thereby distribute heat throughout reformation region Sonic welding to form lap Seal 724 along the length of the 862 in support of the reformation process therein. Exhaust now tubular structure. Lap seal 724 was established by using conduits 843 may take a variety of forms, including finned the ultraSonic welding parameterS Specified above. Lap Seal tubes and Spirals, to provide Substantial Surface area and 724 was then folded over against the membrane tube to desirable uniform distribution of heat throughout reforma conform to a cylindrical shape. Copper end caps 730 (FIG. tion region 862.

16) were then fitted to the membrane tube ends and brazed Still referring to FIG. 19, product stream 803 emerging in place at joints 731 (FIG. 17) using standard copper/ from membrane module 854 travels through a conduit 856 phosphorous or copper/silver/phosphorous brazing alloys having therein a methanation catalyst 804. Conduit 856 and a hydrogen/air or hydrocarbon/air (e.g., methane, 35 passes through the reformation region 862 and through the propane, or acetylene) torch. The brazing alloy is applied vaporization chamber 820 and thereby collects heat energy only to copper end caps 730 and copper foil frame 706. therefrom in Support of the methanation proceSS occurring in Important to note, establishing braze joints 731 coupling end conduit 856. The distal end 814 of conduit 856 provides a caps 730 to the cylindrical form of assembly 720 does not product outlet, i.e., provides hydrogen in Sufficiently purified expose the delicate palladium alloy membrane foil 702 to 40 form for application to, for example, PEM fuel cell 16 (FIG. liquid phase material, i.e., does not destroy the delicate, thin 1).

foil 702. Because the various ultrasonic welds 712 and 724 FIGS. 20 and 21 illustrate a membrane frame and per establish a gas-tight Seal and the braze joints 731 also meate frame, respectively, employed in the membrane mod establish a gas-tight Seal, hydrogen passes from a reforma ule 854 of FIGS. 18 and 19. In FIG. 20, the membrane frame tion process external of tube 700 only through foil 702. At 45 870 includes a circular copper or nickel frame 870a with a least one end cap 730 was fitted with a port 732 and outlet rectangular center cut out 870b. A rectangular palladium 734 to collect the permeate hydrogen from the inside, or alloy membrane 870c, oversized relative to center cut out bore, of the membrane tube. Within tube 700, a methanation 870b, is joined at seals 870d to the frame 870a. By using catalyst 740 may be employed whereby purified hydrogen ultrasonic welding to establish seals 870d about the periph may be taken from membrane tube 700 as described herein 50 ery of palladium alloy membrane 870c, a gas-tight seal above. Thus, membranes 700 So constructed are Suitable for results between membrane 870c and frame 870a. Finally, the high preSSure feed gas to be passed over the external membrane frame 870 includes a feed manifold aperture 872 Surface of the membrane tube, with the permeate collected and a permeate manifold aperture 874.

at the interior Surface of the membrane. In FIG. 21, a permeate frame 876 includes a central cut FIG. 18 illustrates in perspective and partially broken 55 out 876a. Cut out 876a includes a first portion generally away, a Steam reformer 812 according to another embodi rectangular and corresponding generally in dimension to ment of the present invention. Reformer 812 employs an membrane 870c. This portion of cut out 876a is occupied by isolated vaporization chamber 820 similar to that of a wire mesh spacer 876b. Other materials that may be used reformer 312 (FIG. 6). More particularly, reformer 812 in place of wire mesh spacer 876b include porous and receives at input conduit 830 a feed stock and conduit 830 60 foamed ceramic, porous and foamed carbon, and porous and delivers this mixture into vaporization chamber 820 at the foamed metal. A second portion of cut out 876a extends vaporization coil 830a. Elevated temperatures within cham peripherally outward to define a permeate manifold 884 and ber 820 vaporize the feed stock provided at input conduit containing therein a wire mesh insert 876c. Frame 876 may 830. Coil 830a passes into and opens into reformation be recessed to accommodate face-to-face contact with frame chamber 862. Vaporized fuel thereby enters the reformation 65 870, i.e., to accommodate membrane 870c as attached to the chamber 862. Chamber 862 is filled with a reformation face of frame 870b. Finally, permeate frame 876 includes a catalyst 863 and steam reformation occurs within steam feed manifold aperture 882.

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As may be appreciated, frame 870 and frame 876 corre FIG. 23 illustrates a Second arrangement for membrane spond in outer dimensions and certain portions align when module components providing a parallel flow configuration, stacked. For example, feed manifold 872 aligns with feed i.e., where the feed Stock Stream divides and has one manifold 882. Also, permeate manifold 874 may be aligned opportunity for exposure to a palladium alloy membrane. In with the Substantially larger permeate manifold 884. Thus, FIG. 23, permeate frames 870' correspond generally to the when appropriately Stacked with other components, previously described permeate frames 870, but include also described more fully hereafter, a membrane module 854 a raffinate manifold 875. Similarly, permeate frame 876 may be established to separate stream 801 into streams 803 corresponds to the previously described permeate frame and 805 as described herein-above. 876, but includes also a raffinate manifold 885. Raffinate FIG. 22 illustrates use of frames 870 and 876 stacked to manifolds 885 and 875 align for fluid communication ther form a series flow arrangement for module 854. In FIG. 22, ebetween when frames 870' and 876' stack as illustrated in permeate frame 876 occupies a central position with a FIG. 23.

membrane frame 870 on each side, i.e., above and below as The arrangement illustrated in FIG. 23 establishes a illustrated in FIG.22. Feed manifold 882 of frame 876 aligns parallel flow of feed gas across the palladium alloy mem with feed manifolds 872 of frames 870. Permeate manifold 15 branes 870c. More particularly, consider a feed gas entering 884 of frame 876 aligns with permeate manifolds 874 of the open central region of the lower feed frame 880. Such frames 870. Feed frames 880 are located at the outward side feed gas is exposed to the membrane 870c of the lower of each of frames 870, i.e., above and below frames 870 as frame 870'. Concurrently, some of the feed gas may divert illustrated in FIG. 22. Each frame 880 is of circular shape across the lower membrane 870c and then travel along the corresponding to that of frames 870 and 876. Each frame raffinate channels established by apertures 875 and 885, or 880 includes an open central region extending laterally along the apertures 872 and 882 and eventually enter the outward to correspond with, i.e., to fluidly couple with, open region of the upper feed frame 880. At this point, the aligned apertures 872 and 882 of frames 870 and 876. Each feed gas is exposed to the membrane 870c of the upper frame 880 also includes a permeate manifold aperture 887 frame 870'. Accordingly, hydrogen present therein may isolated relative to the center cut out portion. 25 migrate across membrane 870c and into the center open Thus, the arrangement illustrated in FIG.22 offers a series region of permeate frame 876'. Thereafter, such hydrogen flow configuration directing the feed gas Sequentially acroSS would pass along manifolds 884 of frame 876' and 874 of successive membranes 870c. For example, consider a feed frames 870' and eventually through apertures 887 for har gas traveling upward through the component Stack illus Vest. In Such parallel flow configuration, all of the feed trated in FIG. 22. AS the feed gas enters the center open channels over the membrane Surfaces are fed from a com region of the lowest frame 880, hydrogen has opportunity to mon feed supply manifold. This favors low pressure drop for pass through the membrane 870c of the lowest membrane the flowing feed gas Stream.

frame 870. AS may be appreciated, any Such hydrogen which The arrangement of membrane component Stacking as does cross the lowest membrane frame 870 migrates into the illustrated in FIGS. 22 and 23 allows series or parallel, open region of permeate frame 876 and can then migrate by 35 respectively, flow of the feed gas through the membrane way of permeate manifolds 884, 874 and 887 out of the module. Because the feed frames 880 are compatible, it is component Stack for harvest. The Series flow arrangement of possible to combine Series flow and parallel flow Stacking FIG. 22 offers a Second opportunity for feed gas to pass arrangements in a Single membrane module. More through a membrane 870c. More particularly, feed gas particularly, an arrangement Such as illustrated in FIG. 22 travels from the open center region of the lowest frame 880 40 may be Stacked adjacent to an arrangement as illustrated in into the feed manifold 872 of the lowest frame 870, through FIG. 23. Multiple combinations of such arrangements may the feed manifold 882 of the permeate frame 876, through be provided in a single membrane module as desired to the feed manifold 872 of the upper frame 870, and into the establish a given first-stage of the hydrogen purifier as central open region of the upper most feed frame 880. In this illustrated in the present invention. open central region, the feed gas is exposed to a Second 45 FIG. 24 illustrates an additional frame component which palladium alloy membrane. More particularly, hydrogen may be incorporated into a membrane module. In FIG. 24, remaining in the feed gas as it enters the open region of the exhaust frame 890 includes a feed manifold aperture 892, a upper frame 880 is exposed to the membrane 870c of the permeate manifold 894, and a raffinate manifold 895. As upper membrane frame 870. Any Such hydrogen crossing may be appreciated, Stacking exhaust frame 890 in a mem this upper membrane 870c enters the central open region of 50 brane module Such as illustrated in FIGS. 22 and 23 allows permeate frame 876 and may then travel along manifolds passage of feed gas through aperture 892, hydrogen product 884, 874 and 887 for harvest. through aperture 894, and passage of raffinate through AS may be appreciated, additional Similar components aperture 895 without otherwise affecting operation of the may be Stacked in the arrangement illustrated in FIG. 22 to membrane modules as described herein above. Exhaust provide Successive opportunity for feed gas exposure to 55 frame 890 includes also an exhaust manifold 897 providing palladium alloy membranes in Series fashion. An actual a lateral passage for hot combustion exhaust gas through implementation would include end plates and necessary frame 890. As may be appreciated, exhaust manifold 897 is outlet and inlet ports for harvesting hydrogen gas and isolated relative to apertures 892,894, and 895. Hot exhaust forcing feed gas into the component Stack as described gas passing through exhaust frame 890 elevates the tem earlier in connection with the plate form membrane module 60 perature of a membrane module including frame 890 and 554. thereby speeds heating of the membrane module during Start In Such Series flow arrangement as illustrated in FIG. 22, up. Exhaust frame 890 may be incorporated into the stacked the feed gas Stream is directed to flow over a first membrane component Structure of a membrane module along with the Surface, then a Second membrane Surface, and So on as other frame members by conventional brazing, gasketing, or desired. Such Series flow arrangement encourages mixing of 65 welding techniques as described herein. the feed gas Stream components after passage over each Stacking and construction of the planar-type components membrane in the membrane module component Stack. as illustrated herein may be executed by use of conventional

Page 28

brazing, gasketing, or welding methods to create a Stacked component membrane module. To establish Seals between the Stacked components of the modules, i.e., the membrane assemblies, permeate and feed frames, exhaust frame Hydrogen Flux Concentration, ppm members, and end plates, brazing, gasketing, or welding std. ft/f? shr Carbon Oxygen Silicon methods are appropriate and may be used without deterio ration of the delicate palladium alloy membranes 870c. For 240 40 25 1O

example, brazing alloy may be applied between adjoining 115 146 25 15 frame elements and the entire assembly heated to achieve a 56 219 25 27 brazed joint within a controlled-atmosphere brazing furnace. 1O

Alternatively, the module may be assembled then welded The hydrogen-permeable membrane does not have to from the exterior, for example, by using an orbital pipe welding machine. In yet another proposed method of manu exhibit other an exceptionally high Selectivity for hydrogen over gases, since the Second Stage of the hydrogen purifier facture of a Sealed membrane module, the components are Serves to further

Stacked and Sufficient pressure applied to the Stack Such that 15 rities that remainreduce the concentration of Selected impu in the permeate hydrogen after passing all joining Surfaces are in intimate pressurized contact. Then, through the membrane. Selectivity is defined as the ratio of heating the entire assembly to between 500 and 800 degrees the permeation rate of hydrogen divided by the permeation Celsius for two hours to eight hours results in intermetallic rate of an impurity. The selectivity for hydrogen exhibited diffusion between the adjoining Surfaces to create a Sealed by the membrane is at least 20, and preferably at least 50. joint. Yet another method for achieving gas-tight Seals is to Use of such membranes with relatively low selectivity use conventional flexible (compressible) graphite gaskets or will not yield a permeate hydrogen Stream that is of accept composite graphite-metal gaskets. able purity for use in a PEM fuel cell. For example, steam Thus, a variety of embodiments, configurations and alter reforming methanol yields a hydrogen-rich reformate Stream natives have been shown for implementing Steam reforma containing about 25% combined CO and CO. A membrane tion under the present invention. Various experiments and 25 with a hydrogen selectivity of 50 will produce a permeate testing procedures have been conducted to prove the viabil hydrogen stream containing 25%/50=0.5% combined CO ity of Steam reformation under the present invention and will and CO. However, this level of impurities is readily treated be described in general terms as follows. with the polishing step (the Second Stage). Thus, the two As disclosed earlier in the preferred embodiments of the Stage hydrogen purifier allows the use of membranes that, present invention, the hydrogen-rich reformate Stream is due to imperfections or otherwise, have relatively low purified by means of a two-stage hydrogen purifier that is Selectivity for hydrogen over other gases. Such membranes also the Subject of this invention. The two-stage hydrogen are much leSS expensive than are membranes that have purifier utilizes a membrane for the first stage to accomplish Substantially higher hydrogen Selectivity (e.g., hydrogen a bulk separation of hydrogen from the reformate Stream. selectivity >1000).

Then, the permeate hydrogen from the first-Stage membrane 35 To obtain a very thin metal hydrogen-permeable mem is Subjected to a polishing step (the Second stage) to further brane without Sacrificing mechanical Strength of the reduce the concentration of Selected impurities, Such as CO membrane, the thin hydrogen-permeable membrane is Sup and CO, to acceptably low levels as required for the ported by a Support layer. The Support layer must be hydrogen to serve as the fuel for PEM fuel cells. For thermally and chemically stable under the operating condi instance, a typical PEM fuel cell using a Standard platinum 40 tion of the membrane, and the Support layer is preferably electrocatalyst requires hydrogen containing <10 ppm CO porous or containing Sufficient voids to allow hydrogen that and, preferably, <100 ppm CO to achieve maximum power permeates the thin membrane to pass Substantially unim output from the fuel cell. peded through the Support layer. Examples of Support layer The membrane used in the first stage of the purifier is materials include metal, carbon, and ceramic foam, porous Selected from hydrogen-permeable and hydrogen-Selective 45 and microporous ceramics, porous and microporous metals, high-temperature membranes. Thermally-Stable membranes metal mesh, perforated metal, and slotted metal. Especially allow the purifier to be thermally integrated with the preferred Support layers are woven metal mesh (also known reformer, eliminating the requirement for cooling the as Screen) and tubular metal tension springs. hydrogen-rich reformate prior to purification, thereby Sim In the event that the membrane is a thin hydrogen plifying the overall System and reducing the cost of the 50 permeable metal (e.g., palladium alloys) and the Support System. layer is composed of a metal, the metal used for the Support Preferred membranes are microporous ceramic, layer is preferably Selected from a corrosion-resistant alloy, microporous carbon, microporous metallic, and dense Such as Stainless Steels and non-ferrous corrosion-resistant metallic membranes. Especially preferred are thin mem alloys comprised of one or more of the following metals: branes composed of hydrogen-permeable and hydrogen 55 chromium, nickel, titanium, niobium, Vanadium, Zirconium, Selective metals including palladium and palladium alloys, tantalum, molybdenum, tungsten, Silicon, and aluminum. nickel and nickel alloys, and the Group 4 and Group 5 metals These corrosion-resistant alloys have a native Surface oxide and their alloys. Thin membranes composed of Pd-40Cu are layer that is chemically and physically very stable and Serves especially preferred for high hydrogen permeability and to Significantly retard the rate of intermetallic diffusion durability. In particular, the Pd-40Cu alloy exhibits highest 60 between the thin metal membrane and the metal Support hydrogen permeability and, therefore, most favorable layer. Such intermetallic diffusion, if it were to occur, often economics, if the Pd-40Cu alloy contains low concentrations results in Significant degradation of the hydrogen perme of carbon and oxygen. The following table demonstrates the ability of the membrane and is undesirable see Edlund, D. correlation between high hydrogen permeability J., and J. McCarthy, “The Relationship Between Interme (represented as hydrogen flux through the 25 micron thick 65 tallic is Diffusion and Flux Decline in Composite-Metal membrane at 100 psig hydrogen, 400 degrees Celsius) and Membranes: Implications for Achieving Long Membrane low carbon content. Lifetimes” J. Membrane., 107 (1995) 147-153).

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The rate of intermetallic diffusion between the thin metal part of the fuel processor, it will be appreciated that the membrane and the metal Support layer may also be retarded two-stage hydrogen purifier may function external to a by applying certain non-porous coatings to the metal Sup conventional process for hydrogen manufacture (e.g., Steam port. Suitable coating materials include aluminum oxide; reformer, partial-oxidation reactor, or autothermal aluminum nitride, Silicon oxide, tungsten carbide, tungsten reformer).

nitride; oxides, nitrides, and carbides of the Group 4 and Concerns over safety call for use of non-flammable fuel Group 5 metals; boron nitride; and boron carbide. Many of feedstocks for use to produce hydrogen by the Steam these coating are employed as hard coatings on tools and reforming process. The advantages of using non-flammable dies, and as release agents. fuel feedstocks include elimination of fire or explosion The Second Stage of the hydrogen purifier is designed to danger due to vapors from the fuel feedstock accumulating further reduce the concentration of impurities that adversely in enclosed environments and, for military applications, affect the power output and operation of the PEM fuel cell. elimination of fire or explosion risk from hot metal frag Particularly, the Second-stage polishing Step is designed to ments Striking and penetrating fuel Storage tanks. remove CO and, to a lesser degree, CO from the hydrogen Non-flammable fuel feedstocks for generating hydrogen that has permeated the first-stage membrane. Furthermore, 15 by Steam reforming and as disclosed in this invention the Second-stage polishing Step is conducted at or near the include polyhydroxy alcohols and polyethers that are mis operating temperature of the first-stage membrane and the cible with water. AS used herein, non-flammable means that reformer, thereby eliminating the need to Substantially heat combustion in normal air at about 1 atm. pressure is not or cool the hydrogen Stream before passage through the Self-Sustaining. Preferred fuels include ethylene glycol, pro polishing Step. By thermally integrating the polishing Step, pylene glycol, and the glycol ethers of ethylene glycol and the need for heat eXchangers is eliminated and the overall propylene glycol (e.g., diethylene glycol). These fuels are operation of the System is simplified and the cost of the collectively called glycols. When mixed with a stoichiomet System is reduced. ric amount of water for Steam reforming (e.g., two molar Suitable chemical operations for the Second-Stage polish equivalents water to one molar equivalent ethylene glycol, ing Step include preferential oxidation of CO, a widely 25 and four molar equivalents water to one molar equivalent practiced method for removing CO from hydrogen fuel propylene glycol), these fuel feedstocks are not flammable streams for PEM fuel cells Swathirajan, S., and H. Fronk, even when Subjected to a propane/air flame from a torch. “Proton-Exchange-Membrane Fuel Cell for Transportation” The flame merely heats the glycol/water mixture until the Proceedings of the Fuel Cells 94 Contractors Review water in the mixture boils. Provided Substantial water is still Meeting, DOE/METC-94/1010, Aug. 17-19(1994) present in the glycol/water mixture, combustion is not 105-108). However, selective oxidation only removes CO Supported.

from the hydrogen Stream, it does not reduce the CO2 The non-flammable nature of the glycol/water mixtures is content. In fact, selective oxidation increases the CO con due to the very low vapor pressure of the glycol component tent of the hydrogen. A preferred chemical operation for the (e.g., ethylene glycol and propylene glycol). For instance, polishing Step is methanation, which removes both CO and 35 the vapor pressure of ethylene glycol is only 20 torr at 100 CO2 from the hydrogen Stream, as represented by the C. Furthermore, the water component of these mixtures, in following chemical reactions: addition to being a necessary reactant for Steam reforming, serves two functions that contribute to the non-flammable nature of these glycol/water mixtures. First, water in the 40 mixture Serves, by evaporative cooling, to reduce the maxi mum temperature to which the mixture can be heated

Methanation occurs rapidly at >300° C. in the presence of a thereby limiting the maximum vapor pressure of the glycol. catalyst, Such as nickel, palladium, ruthenium, rhodium, and Second, as water evaporates at the Surface of the mixture, the platinum. Preferably, methanation is conducted at 400 C. to water vapor dilutes oxygen (from air) at the Surface of the 600 C. in the presence of a commercial supported nickel 45 glycol/water mixture. Since oxygen is necessary for reforming or methanation catalyst such as R1-10 and G1-80 combustion, and combustion is generally favored by high manufactured and sold by BASF. oxygen concentrations, Substantial dilution of oxygen from As the embodiments described earlier have shown, the air by evaporating water Serves to reduce the flammability of first Stage and Second Stage of the hydrogen purifier can be the glycol/water mixture.

integrated So that they are in close proximity, thereby 50 Thus, certain feedstock mixtures are non-flammable. Sim minimizing heat loSS as well as reducing the size, weight, ply Stated, to be non-flammable the vapor pressure of the and cost of the hydrogen purifier. For example, if a tubular combustible component, i.e., organic component, of the fuel membrane is used as the first Stage, the Second-stage pol feedstock must remain below the lower flammability limit at ishing Step may be located within the bore of the membrane 100 C.; the approximate temperature at which water in the tube at the permeate Side of the membrane. If a plate-type 55 mixture will boil. Generally, this requires that the organic membrane is Selected, the polishing Step may be located at component have a vapor pressure <100 torr at 100° C. the permeate Side of the membrane between membrane In addition to being non-flammable, glycol/water plates, or it may be located in a tube or other shape that is mixtures, best known for their use as heat eXchange fluids in directly connected to the plate-type membrane at the internal combustion engines, are converted to a hydrogen permeate-hydrogen discharge port. Furthermore, if the 60 rich reformate Stream in the presence of nickel-based Steam membrane is Supported for Strength, and if the polishing Step reforming catalysts at temperatures in the range of 400 C. is methanation, the methanation catalyst may be incorpo to 700° C. Glycol/water mixtures also offer the advantage of rated within the Support for the membrane. For instance, the forming Stable Solutions over a wide range of water membrane Support may comprise a nickel or other metal concentration, So that the proper water to glycol Steam mesh with a high nickel Surface area. 65 reforming ratio can be obtained by appropriately mixing the While previously disclosed embodiments of the invention glycol/water fuel feedstock and then dispensing this fuel have shown the two-stage hydrogen purifier as an integral feedstock into a Supply tank (or reservoir) from which the

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fuel feedstock is delivered at the proper rate to the reformer. The reformer was operated in this mode, without any Yet another advantage of the glycol/water mixtures is that external Source of heating, for 6 hours at which time the they remain liquid over a large temperature range, and they experiment was concluded.

are generally Viscous liquids. Glycol/water mixtures, Sold According to a Second example, tubular Pd-25Ag mem commercially as antifreeze coolants, remain liquid even at branes with a 2.2 cm outside diameter were made using the temperatures well below 0° C. and at temperatures greater general method described in connection with FIGS. 12-17. than 100° C. Being liquid, glycol/water mixtures are effi The Pd-25Ag foil was 25 micron thick and 7.0 cm wide by ciently pumped to elevated preSSure for delivery to the 16 cm long and the copper foil frame was 125 micron thick reformer So that Steam reforming can be conducted at and 8.3 cm wide by 17.8 cm long. The dimensions of the elevated pressure (up to 500 psig, but preferably 100 psig to 1O center cut out in the copper foil frame was 5.7 cm wide by 300 psig). The high viscosity of glycol/water mixtures leads 14 cm long. The welding equipment and methods described to greater pumping efficiency, particularly if a gear pump, in connection with FIGS. 12-17 were used to join the piston pump, or centrifugal pump is used to deliver the palladium-alloy foil to the copper foil frame. The Support for high-pressure fuel feedstock to the reformer. The high the membrane was a carbon Steel tension Spring, 2.2 cm Viscosity reduces Slippage past the wetted Surfaces of the 15 outside diameter. The Spring was made using wire nominally pump, which often limits the maximum pressure differential 0.25 cm diameter. End caps were brazed to the ends of the at which a pump may be used. membrane tube using the method given above or, in Some To demonstrate the integrated fuel processor of this cases, end caps were Sealed to the ends of the membrane invention, the fuel processor depicted generally in FIG. 5 tube using graphite Seals. The graphite Seals were achieved was constructed and operated. The tubular metal membrane using flexible graphite tape (1.3 cm wide) wrapped around (first stage of the hydrogen purifier) was made using the the membrane tube and then compressed against the mem method generally described in connection with FIGS. brane in a Standard compression fitting.

12-17. The hydrogen-permeable metal foil 702 consisted of In another example, plate-type membrane modules were Pd-40Cu nominally 25 microns thick, and the membrane made using the following general method. Hydrogen was about 15 cm long (2.8 cm outside diameter). The Second 25 permeable Pd-40Cu foil, nominally 25 micron thick and 5.1 Stage of the hydrogen purifier, a catalytic methanizer, was cm by 5.1 cm Square, were welded to a copper foil frame contained in a copper tube, 1.8 cm outside diameter, that was (nominally 125 micron thick) using the ultrasonic welder inserted inside the bore of the tubular membrane 700. One and welding parameters discussed above. The copper foil end of the copper methanation tube was Sealed to one of the frame was circular in shape (8.9 cm diameter) with cut outs tubular-membrane end caps 730. The other end of the copper for feed and permeate as shown in FIG. 20. After welding methanation tube was terminated about 0.3 cm from the end the Pd-40Cu membrane to the copper foil frame to make the of the membrane tube whereby hydrogen permeating to the membrane assembly, the Weld was checked for leaks by a inside of the membrane tube 700 would freely flow into the Standard dye penetration test.

open end of the methanation tube Such as shown generally The copper permeate plate (FIG. 21) was 0.3 cm thick and in FIG. 3. The methanation tube was filled with catalyst 35 8.9 cm diameter. A recessed was machined in the permeate G1-80 (BASF), a supported nickel composition that is active plate to accept the Support layer for the membrane. This for methanation of CO and CO. receSS, as shown in FIG. 21, was of the Same dimensions as The reforming region of the fuel processor was filled with the membrane and connected to the permeate manifold catalyst K3-110, a copper/zinc Supported catalyst Sold by channel. The Support layer consisted of a first layer of BASF generally for conducting the water-gas shift reaction 40 Stainless Steel Screen (70x70 mesh), placed against the at <350° C. The shell of the fuel processor, the spiral permeate plate, then a Second layer of StainleSS Steel Screen combustion tube, and the end plates were all constructed (200x200 mesh) that the thin Pd-40Cu foil rested against. from StainleSS Steel. Insulation was placed around the eXte This combination of coarse mesh and fine mesh was deter rior of the Shell and end plates to reduce heat loss. mined to both adequately Support the thin membrane with The fuel processor was operated using methanol/water 45 out excessively damaging the membrane, and provide mix as the feed. The methanol/water Solution was prepared acceptably low resistance to the lateral flow of permeate by mixing 405 mL methanol (histological grade, Fisher hydrogen.

Scientific) with 180 mL deionized water. The fuel processor The Stainless Steel Screen was fixed to the permeate plate was heated to 200 C. to 300° C. using an externally placed with a single drop of cyanoacrylate glue, and the glue electric resistance heater. Once the fuel processor was hot, 50 allowed to dry. Then, two membrane assemblies were the electric heaters were turned off and methanol/water brazed to a Single permeate plate, one membrane assembly Solution was pumped into the fuel processor at 200 psig. The at each major Surface of the permeate plate. Brazing was methanol/water feed was first vaporized then the vapors achieved using a standard brazing alloy (nominally 80% passed over the K3-110 reforming catalyst to produce copper, 15% silver, and 5% phosphorous) in either ribbon hydrogen-rich reformate. The two-stage hydrogen purifier 55 form or as a paste (powdered brazing alloy mixed with a then extracted product hydrogen at ambient pressure from paste binder). This brazing alloy was purchased from Lucas the hydrogen-rich reformate. The hydrogen-depleted raffi Milhaupt, Inc. (Cudahy, Wis.). To prevent unwanted creep of nate was directed to the combustor as described above. the brazing alloy over the surface of the Pd-40Cu membrane, Combustion of this raffinate gas inside the fuel processor Nicrobraz, Red Stop-Off Type II (Wall Colmonoy Corp., heated the fuel processor to 300° C. to 350° C. and provided 60 Madison Hits., Mich.) was applied around the edge of the all required heat once operation of the fuel processor com Pd-40Cu membrane. This assembly was then placed on a flat menced. Surface beneath a steel weight (approximately 1.5 kg) and The purity of the product hydrogen was determined by heated to 750° C. in a brazing furnace. A coating of boron gas chromatography and the flow rate of the product hydro nitride, a release agent, was applied to the Steel Surfaces in gen was measured using a calibrated gas flow meter. Analy 65 contact with the membrane assembly during brazing to sis of the product hydrogen confirmed <10 ppm CO and <10 prevent Sticking between the membrane assembly and the ppm CO2. The flow rate of product hydrogen was 2 L/min. Steel Surfaces. Brazing was done under vacuum, a nitrogen

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atmosphere, or a nitrogen Stream containing a low concen overall length of the membrane tube (including end caps) tration of methanol or hydrogen to Serve as a reducing gas was approximately 21 cm. This tubular membrane Serves as (to prevent oxidation). The brazing temperature of 750° C. the first Stage of the purifier. The Second Stage of the purifier, was held for 15 minutes prior to cooling. a catalytic methanizer, was contained in a copper tube, 1.58 To demonstrate the non-flammability of ethylene glycol/ cm outside diameter, that was inserted inside the bore of the water mixtures, the following experiment was conducted. tubular membrane. One end of the copper methanation tube Ethylene glycol (1.0 mL) was mixed with two molar equiva was Sealed to one of the tubular-membrane end caps. The lents water (0.65 mL). The resulting homogeneous Solution other end of the copper methanation tube was terminated is of the proper Stoichiometry for Steam reforming, as shown about 0.3 cm from the end of the membrane tube so that by the following ideal reaction equation: hydrogen permeating to the inside of the membrane tube would freely flow into the open end of the methanation tube (this arrangement is shown in FIG.3). The methanation tube

This Solution of ethylene glycol and water was directly was filled with catalyst G1-80 (BASF), a supported nickel exposed to the flame from a propane/air torch. The ethylene composition that is active for methanation of CO and CO. glycol/water Solution did not burn or Support combustion. 15 This two-stage hydrogen purifier was placed in a stainless In yet another example, a 2:1 molar ratio of water-to Steel shell equipped with electric resistance heaters. The ethylene glycol was prepared by mixing 65 mL deionized hydrogen purifier was heated to 300° C. to 350° C., and water and 100 mL purified reagent grade (Fisher Scientific) methanol/water reformate (approximately 70-75% to form a homogeneous Solution. This ethylene glycol/water hydrogen, balance CO and CO2) at 50 psig was passed into Solution was reformed to produce hydrogen in a laboratory the stainless steel shell and over the exterior Surface of the Scale packed-bed catalytic reactor as described below. Pd-25Ag membrane tube. Product hydrogen at ambient The catalytic reactor consisted of a cylindrical Stainless preSSure, after permeation through the Pd-25Ag membrane steel shell 2.5 cm inside diameter and 22.9 cm long. The and then passage over the methanation catalyst, was col reactor contained a fixed bed of the commercial catalyst lected and analyzed by gas chromatography. Analysis con G1-80 (BASF), which is a supported nickelsteam reforming 25 firmed that the product hydrogen contained <2 ppm CO and catalyst. A length of Stainless Steel tubing (0.3 cm diameter <50 ppm CO.

by about 25 cm long) was coiled around one end of the Thus, a Steam reformer with internal hydrogen purifica catalytic reactor to Serve as a preheater and vaporizer for the tion has been shown and described. The reformer of the ethylene glycol/water feed. One end of this vaporization coil present invention utilizes a single feed, e.g., a methanol and was connected to the inlet of the catalytic reactor, the other water or hydrocarbon and water mix, as both the chemical end of the coil was connected to a reservoir containing the feed Stock to Support hydrogen reforming and also as a ethylene glycol/water feed. The temperature within the combustion fuel Source to provide Sufficient temperature to catalytic reactor was measured and controlled via a thermo Support Steam reforming. The present invention recovers by couple inserted within the catalyst bed. design less than a maximum amount of hydrogen available The catalytic reactor was heated to 500 C. by means of 35 in a reforming Step to leave in the byproduct Stream Suffi an external electric furnace. The G1-80 catalyst was then cient hydrogen as fuel to Support the combustion process. reduced in Situ by first flowing ethylene glycol/water feed The present invention uses two distinct hydrogen purifica into the catalytic reactor at a rate of 2.5 mL/min (liquid flow tion processes. First, a membrane produces a hydrogen rate) for 2 hrs, then flowing pure hydrogen at ambient Stream as a bulk filtration Step, but the product hydrogen preSSure through the catalytic reactor for another 4 hrs. 40 Stream may still contain Some undesirable impurities. Following reduction of the Steam reforming catalyst, ethyl Second, a polishing process converts the undesirable impu ene glycol/water feed was admitted into the catalytic reactor rities in the hydrogen Stream to innocuous components not at ambient pressure. The temperature of the catalytic reactor affecting operation of, for example, a fuel cell. was varied between 400 C. and 500 C. The product gas Advantageously, this allows use of a relatively leSS was shown to be predominantly CO2 and H2 by gas chro 45 expensive, thin palladium-alloy membrane in the Steam matography analysis, unreacted ethylene glycol/water was reforming process.

collected in a cold trap and quantified by gravimetric In FIG. 25, another embodiment of the fuel processor, or analysis, and the product flow rate was measured using a reformer, is shown and generally indicated at 900. Similar to calibrated gas flow meter to determine the degree of con the previously described embodiments, reformer 900 version to products. The results of these experiments are 50 includes a shell 902 that houses steam reforming 904 and Summarized in the following table. combustion 906 regions, as well as at least one Steam reforming tube 908. Three such tubes are shown in FIG. 25, and each contains steam reforming catalyst 910. It should be

Temperature understood that, like the rest of the reformers disclosed ( C.) herein, reformer 900 may include as few as one tube and Product Flow Rate (L/min) Conversion to Products (%)

preferably includes multiple tubes. Between six and ten 500 +/- 50 3-5 90-95 reforming tubes have proven effective, both in hydrogen 465 +/- 25 4-5 90-95 production rate and compactness of the Overall reformer.

However, the number of tubes in any particular embodiment 60 may vary, depending upon Such factors as the Size of the

To demonstrate the utility of the two-stage hydrogen reformer's shell, the desired rate of hydrogen production, purifier when utilized as a Stand-alone hydrogen purifier, the and the number of additional elements within the shell. For following experiment was conducted. example, when a plate-type membrane module is used, there A tubular hydrogen-permeable metal membrane was is more available Space adjacent the Side walls of the made using the method described in FIGS. 12-17. The 65 reforming tubes.

membrane consisted of Pd-25Ag foil nominally 25 micron As shown in FIG. 25, a portion 911 of each reforming tube thick and was 2.2 cm outside diameter by 15 cm long, the 908 extends external shell 902. This enables the tubes (and

Page 32

the reforming catalyst contained therein) to be accessed nation catalyst (not shown) to convert carbon monoxide and without having to open the shell. In this configuration each carbon dioxide in the permeate Stream into methane. end portion 911 includes a removable cap or other closure As shown in FIG. 25, polishing catalyst bed 934 is located which may be Selectively removed to permit access to the external shell 902, where it is heated by radiant heat and interior of the tube, and thereafter replaced. This configu thermal conduction from hot shell 902. As shown, bed 934 ration for the reforming tubes may be used with any of the lies against the exterior surface 936 of shell 902. However, other reformers disclosed herein, just as reformer 900 may it is within the scope of the invention that bed 934 may be include reforming tubes which are completely housed within at least partially or completely spaced away from shell 902, Shell 902. So long as it still receives Sufficient heat for the polishing Tubes 908 are heated by hot combustion gasses passing reaction. Polishing catalyst bed 934 is further heated by the from internal combustion manifold 912 to internal exhaust hot hydrogen that flows into the bed from the methanation manifold 914, and ultimately exiting reformer 900 through module 930. Finally, purified hydrogen exits reformer 900 outlet 916. In FIG. 25, a plurality of passages 918 are shown via tube 938. By locating the polishing catalyst bed external which permit the hot combustion gasses to pass between shell 902, reformer 900 may either include additional manifolds 912 and 914, and thereby heat tubes 908 as the 15 reforming tubes within its shell, or the shell may be smaller gasses flow around the tubes. because it no longer needs to house the polishing catalyst Hot combustion gasses are produced by burner 920. Upon bed.

initial startup, burner 920 is ignited by a suitable ignition It should be understood that as used herein, purified Source, Such as Spark plug 922, or any of the other ignition hydrogen refers to a stream that is at least Substantially Sources disclosed herein. Combustion air, preferably at or comprised of hydrogen gas. The Stream may include other near ambient pressure, is brought into burner 920 through components, Such as methane produced in the polishing combustion port 924. catalyst bed, but the Stream contains less than defined Feedstock for the Steam reforming process is admitted minimum amounts (i.e. trace concentrations) of impurities into the fuel processor through inlet tube 926 and passes into (Such as carbon monoxide and carbon dioxide) which would the hot combustion region 906 of fuel processor 900, 25 harm or lessen the effectiveness of a fuel cell. wherein the feedstock is vaporized. A single inlet tube 926 Waste gasses, including Some of the produced hydrogen may be used to admit a feedstock comprising alcohol and gas, that do not pass through the hydrogen-Selective mem water, or multiple separate inlet tubes may be used (such as brane within module 930 are used as fuel to heat fuel disclosed herein) if the feedstock consists of Separate processor 900. Therefore, the hydrogen-depleted raffinate Streams of water and a hydrocarbon or alcohol. AS Shown in stream (which exits module 930 through conduit 940) is FIG. 25, inlet tube 926 forms a coil 927 that extends around directed into burner 920. As discussed previously, the con tubes 908 multiple times before entering a distribution centration of hydrogen within the raffinate Stream may be manifold 928. Coil 927 should be of Sufficient length that the Selectively controlled So that there is Sufficient fuel gas to feedstock is vaporized prior to reaching distribution mani maintain reformer 900 within desired temperature ranges. fold 928. It should be understood that the circuitous path of 35 FIG. 25 illustrates other non-essential elements that may coil 927 is shown in FIG. 25 for purposes of illustrating one be used within any of the reformers disclosed herein. For possible path. The important concern is that the coil is of example, in FIG. 25, reformer 900 further includes a pres Sufficient length that the feedstock passing there through is Sure gauge 942 for monitoring the pressure of the fuel gas in vaporized by heat transmitted to it as it travels to distribution conduit 940, a pressure relief valve 944, and a vent valve manifold 928. To aid with the vaporization of the feedstock, 40 946. Also illustrated are a valve 948, which controls the flow multiple coils of tubing may be used to effectively increase of fuel gas in conduit 940 to the burner and applies back the heat transfer Surface area of the tubing, and thereby aid pressure on the reforming region, and a valve 949, which in the vaporization of the feedstock. Vaporization of the controls the flow of start-up fuel gas (previously produced feedstock may also be accomplished using plate-type vapor and stored or Supplied from an external Source), Such as ZCS. 45 hydrogen, propane or natural gas, during a cold Start-up of From distribution manifold 928, the vaporized feedstock the reformer.

is distributed to steam reforming tubes 908. When tubes 908 In FIG. 26, a variation of the reformer of FIG.25 is shown are of Similar size or are adapted to process generally equal and generally indicated at 950. Unless otherwise indicated, volumes of feeds, the feedstock is evenly distributed reformers 900 and 950 contain the same components and between the tubes by manifold 928. However, the feedstock 50 Subcomponents. To provide more space within shell 902, may be otherwise proportioned if the tubes are adapted to and thereby permit additional reforming tubes 908 to be receive and process different flows of the feedstock. housed therein, reformer 950 includes vaporization coils 952 Within reforming tubes 908, the feedstock undergoes a which are located external shell 902. As shown, coils 952 are catalytic reaction to yield a hydrogen-rich reformate gas wrapped around the external Surface 936 of shell 902 and are Stream which contains carbon monoxide and carbon dioxide 55 in contact therewith. Similar to the polishing catalyst bed in addition to hydrogen. To purify the produced hydrogen, described with respect to FIG. 25, coils 952 may be at least fuel processor 900 includes a purification module (or mem partially or completely spaced apart from shell 902. In this brane module) 930, through which the reformate gas stream case, the important factor is that Sufficient heat is transmitted is passed. One or more hydrogen-Selective inorganic to the feedstock within the coils to vaporize the feedstock membranes, Such as any of the hydrogen-Selective metal 60 before it reaches distribution manifold 928. In the position (and preferably palladium alloy) membranes disclosed shown in FIG. 26, the coils are heated by radiation and herein, are contained within module 930. Membrane module thermal conduction from the hot Surface of shell 902. 930 may include any suitable configuration, including those The reformer shown in FIG. 26 also demonstrates struc previously described herein. The hydrogen that permeates ture for admitting immiscible feedstocks to the reformer. AS the hydrogen-Selective membranes passes from the module 65 shown, reformer 950 includes an inlet tube 954 through through an outlet port 932 and into a polishing catalyst bed which a water feed is received and delivered to vaporization 934. Preferably, the polishing catalyst bed contains a metha coils 952. A hydrocarbon or alcohol feed is admitted through

Page 33

inlet tube 956, and it is mixed with the hot steam before a reforming region within the shell and including a passing into the reformer through a reformer inlet tube 958. reforming catalyst bed adapted to receive a reforming The combined feedstock Stream passes into one end of a feedstock and convert the feedstock into a reformate mixing chamber 960, which contains an optional static Stream comprising hydrogen, carbon monoxide and mixer or a packing (not shown) to promote turbulent flow carbon dioxide;

and thereby encourage mixing of the vaporized feedstockS. a hydrogen purification module within the shell and The mixed, vaporized feedstock exit the mixing chamber including a hydrogen-Selective membrane in fluid com and are delivered to distribution manifold 961, which in turn munication with the reforming catalyst bed and adapted distributes the feedstock to the reforming tubes. to produce a permeate Stream comprised of the portion To increase the energy efficiency and to increase the 1O of the reformate Stream which passes through the combustion chamber temperature within reformer 950, membrane, and a byproduct Stream comprised of the reformer 950 includes a quenching chamber 962 adapted to portion of the reformate Stream which does not pass partially quench the reformate gas Stream prior to its through the membrane;

entrance into membrane module 930. As shown, the refor a polishing catalyst bed within the shell and including a mate gas Stream must pass through chamber 962 after 15 methanation catalyst, wherein the polishing catalyst exiting reforming tubes 908 and prior to entering membrane bed is in fluid communication with the hydrogen puri module 930. Chamber 962 includes a pair of ports 964 and fication module and is adapted to receive the permeate 966 through which combustion air respectively enters and Stream therefrom and produce a product Stream from the permeate Stream, wherein the polishing catalyst bed exits the chamber. The air is cooler than the reformate gas is adapted to reduce the concentration of carbon diox Stream, and therefore cools tee reformate gas Stream prior to ide and carbon monoxide in the permeate Stream by its entry into the membrane module. During this exchange, catalytic reaction to produce methane, and the combustion air is heated prior to its entry to burner 920. a combustion chamber adapted to receive and combust a The quenching chamber and external vaporization coils fuel Stream with air to generate heat for heating the described with respect to reformer 950 may be used with any reformer, wherein the polishing catalyst bed is ther of the reformers (aka fuel processors) described herein. 25 mally coupled to the combustion chamber to be heated Similarly, the external polishing catalyst bed may be used thereby.

with any of the reformers described herein, Such as to 2. The reformer of claim 1, wherein the polishing catalyst increase the number of reforming tubes within the reform bed is fluidly isolated from the combustion chamber so that er's shells or to decrease the size of the shell. It should be combustion fluid in the combustion chamber does not enter understood that the reformers described herein have been the polishing catalyst bed. shown and described to illustrate particular features of the 3. The reformer of claim 1, wherein the fuel stream is at invention, and that particular elements or configurations least partially comprised of the byproduct Stream. may be selectively used with any of the reformers described 4. The reformer of claim 1, wherein the polishing catalyst herein. bed is located at least Substantially within the combustion In many of the previously described embodiments, the 35 chamber.

end plates and/or membrane modules of the reformers (or 5. The reformer of claim 1, wherein the combustion fuel processors) are Secured to the rest of the reformers with chamber receives air for Supporting combustion from a bolts and gaskets. It should be understood that any other cathode air Stream discharged from a fuel cell. Suitable form of fastening mechanism and Seal may be used 6. The reformer of claim 1, wherein the combustion So long as the Shell is Sealed against leaks and Secured 40 chamber includes an oxidation catalyst. together So that it does not unintentionally open, Such as 7. The reformer of claim 1, wherein the combustion during operation. Although welding and other more perma chamber includes a burner.

nent fasteners are within the Scope of Suitable fastening 8. The reformer of claim 1, wherein the reforming feed mechanisms, fastening mechanisms which may be selec Stock is preheated prior to passage into the reforming region tively removed and reSecured, Such as the bolts and nuts 45 by heat eXchange with at least one of the product Stream and shown for example in FIGS. 25 and 26, are preferred. an exhaust Stream from the combustion chamber. While the invention has been disclosed in its preferred 9. The reformer of claim 1, wherein the reforming feed form, the Specific embodiments thereof as disclosed and Stock is preheated prior to passage into the reforming region illustrated herein are not to be considered in a limiting Sense by countercurrent heat eXchange with at least one of the as numerous variations are possible. Applicants regard the 50 product Stream and an exhaust Stream from the combustion subject matter of the invention to include all novel and chamber.

non-obvious combinations and Subcombinations of the Vari 10. The reformer of claim 1, wherein the reformer is ous elements, features, functions and/or properties disclosed further adapted to receive a liquid-phase feedstock as the herein. No Single feature, function, element or property of reforming feedstock and vaporize the liquid-phase feedstock the disclosed embodiments is essential. The following 55 prior to delivery to the reforming catalyst bed. claims define certain combinations and Subcombinations 11. The reformer of clam 10, wherein the reformer which are regarded as novel and non-obvious. Other com includes a conduit through which the reforming feedstock is binations and Subcombinations of features, functions, ele passed prior to delivery to the reforming catalyst bed, and ments and/or properties may be claimed through amendment further wherein while in the conduit, the reforming feed of the present claims or presentation of new claims in this or 60 Stock is maintained free from contact with the reforming a related application. Such claims, whether they are broader, region yet in thermal communication with the reforming narrower or equal in Scope to the original claims, are also region.

regarded as included within the Subject matter of applicants 12. The reformer of claim 11, wherein the conduit extends invention. at least partially through the reforming catalyst bed. We claim: 65 13. The reformer of claim 11, wherein the conduit enables 1. A Steam reformer, comprising: countercurrent heat eXchange between the reforming feed a shell having an outer Surface; Stock and the reforming region.

Page 34

14. The reformer of claim 10, wherein the reformer 33. The reformer of claim 1, wherein the polishing includes a conduit through which the reforming feedstock is catalyst bed further extends at least partially beyond the passed prior to delivery to the reforming catalyst bed, and shell.

further wherein while in the conduit, the reforming feed 34. The reformer of claim 1, wherein the fuel stream is at Stock is maintained free from contact with the combustion least Substantially comprised of the byproduct Stream. chamber yet in thermal communication with the combustion 35. The reformer of claim 1, wherein the fuel stream is chamber. completely comprised of the byproduct Stream. 15. The reformer of claim 1, wherein the reformer 36. A Steam reformer, comprising: includes a vaporization region within the shell through a shell having an outer Surface; which the feedstock is received and vaporized prior to 1O a reforming region within the shell and including a entering the reforming region. reforming catalyst bed adapted to receive a reforming 16. The reformer of claim 15, wherein the vaporization feedstock and convert the feedstock into a reformate region is maintained at a greater temperature than the Stream comprising hydrogen, carbon monoxide and reforming region. carbon dioxide;

17. The reformer of claim 15, wherein the vaporization 15 a hydrogen purification module within the shell and region includes a mixing chamber through which a first including a hydrogen-Selective membrane in fluid com Vaporized component of the reforming feedstock is mixed munication with the reforming catalyst bed and adapted with a Second, at least partially liquid-phase component of to produce a permeate Stream comprised of the portion the reforming feedstock.

18. The reformer of claim 17, wherein the mixing cham of the reformate Stream which passes through the ber includes means for promoting turbulent flow of the membrane, and a byproduct Stream comprised of the components through the mixing chamber. portion of the reformate Stream which does not pass 19. The reformer of claim 1, wherein the reformer further through the membrane;

includes a vaporization region through which the feedstock a polishing catalyst bed within the shell and including a is received and vaporized prior to entering the reforming 25 methanation catalyst, wherein the polishing catalyst region, and further wherein the vaporization region is at least bed is in fluid communication with the hydrogen puri partially located external the shell while remaining in ther fication module and is adapted to receive the permeate mal communication with the shell. Stream therefrom and produce a product Stream from 20. The reformer of claim 1, wherein the reformer further the permeate Stream, wherein the polishing catalyst bed includes a quenching chamber in fluid communication with is adapted to reduce the concentration of carbon diox the reforming region and the hydrogen purification module, ide and carbon monoxide in the permeate Stream by wherein the quenching chamber is adapted to receive the catalytic reaction to produce methane, and reformate Stream prior to entry to the hydrogen purification a combustion chamber adapted to receive and combust a module and to reduce the temperature of the reformate fuel Stream with air to generate heat for heating the Stream by heat eXchange with a cooler Stream. 35 reformer, wherein the combustion chamber receives air 21. The reformer of claim 20, wherein the cooler stream for Supporting combustion from a cathode air Stream is an air Stream. discharged from a fuel cell. 22. The reformer of claim 21, wherein the cooler stream 37. The reformer of claim 36, wherein the polishing is an air Stream in fluid communication with the combustion catalyst bed is fluidly isolated from the combustion chamber chamber. 40 So that combustion fluid in the combustion chamber does not 23. The reformer of claim 1, wherein the feedstock is enter the polishing catalyst bed.

comprised of water and at least one of an alcohol and a 38. The reformer of claim 36, wherein the fuel stream is hydrocarbon. at least partially comprised of the byproduct Stream. 24. The reformer of claim 1, wherein a portion of the 39. The reformer of claim 36, wherein the polishing reforming catalyst bed extends external the shell. 45 catalyst bed is located at least substantially within the 25. The reformer of claim 24, wherein the reforming combustion chamber.

region includes a plurality of reforming catalyst beds. 40. The reformer of claim 36, wherein the combustion 26. The reformer of claim 25, wherein the reformer chamber includes an oxidation catalyst. further includes a distribution manifold adapted to receive 41. The reformer of claim 36, wherein the combustion the reforming feedstock and distribute the reforming feed 50 chamber includes a burner.

Stock to the plurality of reforming catalyst beds. 42. The reformer of claim 36, wherein the reforming 27. The reformer of claim 1, wherein the amount of feedstock is preheated prior to passage into the reforming hydrogen in the product Stream is less than a Stoichiometri region by heat eXchange with at least one of the product cally available amount of hydrogen. Stream and an exhaust Stream from the combustion chamber. 28. The reformer of claim 27, wherein the amount of 55 43. The reformer of claim 36, wherein the reforming hydrogen in the product Stream is between approximately feedstock is preheated prior to passage into to reforming 50% and approximately 80% of the stoichiometrically avail region by countercurrent heat eXchange with at least one of able hydrogen. the product Stream and an exhaust Stream from the combus 29. The reformer of claim 1, wherein the hydrogen tion chamber.

Selective membrane is formed from at least one of palladium 60 44. The reformer of claim 36, wherein the reformer is and a palladium alloy. further adapted to receive a liquid-phase feedstock as the 30. The reformer of claim 29, wherein the hydrogen reforming feedstock and vaporize the liquid-phase feedstock Selective membrane contains less than 200 ppm carbon. prior to delivery to the reforming catalyst bed. 31. The reformer of claim 30, wherein the hydrogen 45. The reformer of claim 44, wherein the reformer Selective membrane contains less than 100 ppm carbon. 65 includes a conduit through which the reforming feedstock is 32. The reformer of claim 31, wherein the hydrogen passed prior to delivery to the reforming catalyst bed, and Selective membrane contains less than 50 ppm carbon. filer wherein while in the conduit, the reforming feedstock

Page 35

is maintained free from contact with the reforming region 55. The reformer of claim 54, wherein the cooler stream yet in thermal communication with the reforming region. is an air Stream.

46. The reformer of claim 45, wherein the conduit extends 56. The reformer of claim 55, wherein the cooler stream at least partially through the reforming catalyst bed. is an air Stream in fluid communication with the combustion 47. The reformer of claim 45, wherein the conduit enables chamber.

countercurrent heat eXchange between the reforming feed 57. The reformer of claim 36, wherein the feedstock is Stock and the reforming region. comprised of water and at least one of an alcohol and a 48. The reformer of claim 44, wherein the reformer hydrocarbon.

includes a conduit through which the reforming feedstock is 58. The reformer of claim 36, wherein a portion of the passed prior to delivery to the reforming catalyst bed, and reforming catalyst bed extends external the shell. further wherein while in the conduit, the reforming feed 59. The reformer of claim 58, wherein the reforming Stock is maintained free from contact with the combustion chamber yet in thermal communication with the combustion region includes a plurality of reforming catalyst beds. chamber. 60. The reformer of claim 59, wherein the reformer 49. The reformer of claim 36, wherein the reformer 15 further includes a distribution manifold adapted to receive includes a vaporization region win the shell through which the reforming feedstock and distribute the reforming feed the feedstock is received and vaporized prior to entering the Stock to the plurality of reforming catalyst beds. reforming region. 61. The reformer of claim 36, wherein the amount of 50. The reformer of claim 49, wherein the vaporization hydrogen in the product Stream is less than a Stoichiometri region is maintained at a greater temperature than the cally available amount of hydrogen.

reforming region. 62. The reformer of claim 61, wherein the amount of 51. The reformer of claim 49, wherein the vaporization hydrogen in the product Stream is between approximately region includes a mixing chamber through which a first 50% and approximately 80% of the stoichiometrically avail Vaporized component of the reforming feedstock is mixed able hydrogen.

with a Second, at least partially liquid-phase component of 25 63. The reformer of claim 36, wherein the hydrogen the reforming feedstock. Selective membrane is formed from at least one of palladium 52. The reformer of claim 51, wherein the mixing cham and a palladium alloy.

ber includes means for promoting turbulent flow of the 64. The reformer of claim 63, wherein the hydrogen components through the mixing chamber. Selective membrane contains less than 200 ppm carbon. 53. The reformer of claim 36, wherein the reformer 65. The reformer of claim 64, wherein the hydrogen further includes a vaporization region through which the Selective membrane contains less than 100 ppm carbon. feedstock is received and vaporized prior to entering the 66. The reformer of claim 65, wherein the hydrogen reforming region, and further wherein the vaporization Selective membrane contains less than 50 ppm carbon. region is at least partially located external the shell while 67. The reformer of claim 36, wherein the polishing remaining in thermal communication with the shell. 35 catalyst bed further extends at least partially beyond the 54. The reformer of claim 36, wherein the reformer shell.

further includes a quenching chamber in fluid communica 68. The reformer of claim 36, wherein the fuel stream is tion with the reforming region and the hydrogen purification at least Substantially comprised of the byproduct Stream. module, wherein the quenching chamber is adapted to 69. The reformer of claim 36, wherein the fuel stream is receive the reformate Stream prior to entry to the hydrogen 40 completely comprised of the byproduct Stream. purification module and to reduce the temperature of the reformate Stream by heat eXchange with a cooler Stream. k k k k k

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UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION

PATENT NO. : 6,221,117 B1 Page 1 of 1

INVENTOR(S) : David J. Edlund and William A. Pledger

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Column 34

Line 67, delete "filler' and insert -- further -- therefor.

Signed and Sealed this

Twenty-seventh Day of November, 2001

7A4, f abée

NICHOLASP. GODICI

Attesting Officer Acting Director of the United States Patent and Trademark Office

Page 37

UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION

PATENT NO. : 6,221,117 B1 Page 1 of 1

INVENTOR(S) : David J. Edlund and William A. Pledger

It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Column 22

Table, lines 1-10, please delete the first entry “240” and insert -- 130 -- therefor. Signed and Sealed this

Sixteenth Day of December, 2003

JAMES E ROGAN

Director of the United States Patent and Trademark Office