Method of operating an internal combustion engine fed with a reformed gas

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METHOD OF OPERATING AN INTERNAL SUMMARY OF THE INVENTION COMBUSTON ENGINE FED WITH A The present invention provides such an improved REFORMED GAS method. The above noted problems are solved by utiliz

BACKGROUND OF THE INVENTION

ing the heat content of the fuel gas and exhaust gas respectively to convert methane endothermically into a

This invention relates to internal combustion engines gas mixture containing carbon monoxide and hydrogen. fed with a fuel gas obtained in a reformed gas generator This gas mixture is fed to one or both the reformed gas in general and more particularly to an improved O generators and, along with the fuel gas, the internal method of operation for such internal combustion en combustion engine.

glnes. The carbon monoxide and hydrogen formed by the Methods of operating internal combustion engines decomposition of the methonal has two possible uses. It with a fuel gas obtained from a gas generator rather can be used in the internal combustion engine and in the reformed gas generator. In the internal combustion than with a liquid fuel are known. Such methods are 15 engine a higher content of carbon monoxide and hydro used because liquid fuel leads to incomplete combustion gen in the fuel gas results in an increase of the octane in the internal combustion engine. This is the result of number and the calorific value. By providing a higher insufficient carburation and poor mixing with combus hydrogen content in the gases in the reformed gas gen tion air leading to the presence of harmful substances in erator, a higher yield of methane and a compensation the exhaust gas. Antiknock agents which are mixed to 20 for the hydrogen deficit which prevails in the reaction the fuel result in additional pollutants which are injuri of hydrocarbons with a lack of oxygen and favors the ous to the health. The level of harmful emissions to the formation of soot is obtained. Through an endothermic air from an internal combustion engine can be substan conversion of the methonal heat is removed from the tially reduced if the engine is operated with a fuel gas exhaust gas of the internal combustion engine or from obtained, for example, from the reaction of a liquid 25 the fuel gas with the heat so removed converted into hydrocarbon fuel and an oxygen containing gas in a chemical energy.

reformed gas generator. It is advantageous if the methanol is thermally de The type of gas generator which is being referred and composed since such a process requires only a minimum the manner of operating such is described, for example of apparatus and is extremely trouble free. It is pre in U.S. application Ser. No. 633,609 filed Nov. 20, 1975 30 ferred that the methanol be decomposed by spraying it which is a continuation in part of U.S. application Ser. into the hot fuel gas coming out of the reformed gas No. 439,870 filed Feb. 6, 1974 now abandoned. In the generator. In this manner the fuel gas is cooled and at method disclosed therein atomized or evaporated liquid the same time enriched with hydrogen and carbon mon fuel containing hydrocarbons is fed, after having air oxide before reaching the internal combustion engine. and/or exhaust gas fed back from the internal combus 35 Furthermore, a part of the enriched fuel gas can be fed tion engine mixed with it, to the reaction chamber of a back into the reformed gas generator to great advan reformed generator where it is catalytically reacted to tage. If such is done, the decomposed methanol prod form a fuel gas containing carbon monoxide, carbon ucts carbon monoxide and hydrogen, particularly the dioxide, methane and/or hydrogen. This fuel gas burns hydrogen, reduce the danger of soot formation and the more completely in the internal combustion engine and quality of the fuel gas produced is improved. results in an extremely low level of harmful exhaust Various embodiments of the method are illustrated. gases. Furthermore, it has a high octane number making The methanol can be evaporated through a heat ex the addition of antiknock agents unnecessary. change with the exhaust gas of internal combustion For use in an internal combustion engine, fuel gas engine. If the heat of evaporation is extracted from the containing carbon monoxide and methane is desireable 45 exhaust least gas, what would normally be waste heat is at partially converted into chemical energy. On other because of the high calorific value of this mixture. A hand if the heat of the fuel gas being fed to the internal fuel gas can be burned in the combustion chamber of the combustion engine is used for evaporating the metha engine more completely and with better control if it nol, the fuel gas is cooled by the methanol decomposi contains hydrogen. Furthermore, in order to achieve 50 tion sufficient filling of the combustion chamber of the inter still further before enteringtemperature at most to the reaction and is cooled nal combustion engine with fuel gas, it is desireable to engine to result in better fillingthe internal combustion of the combustion cham feed a fuel gas which is as cool as possible. It is very bers.

difficult to fulfill all these requirements which the fuel gas should simultaneously meet. Furthermore, if the 55 in All which that is required for implementing these methods the methanol is thermally decomposed is basi reaction of hydrocarbons with a gas containing oxygen cally a supply tank and an injection device for the meth takes place at low temperatures, up to the thermal equi anol. The advantage of the simplicity of the construc librium, soot occurs. Formation of soot, however, can tion of the apparatus for carrying out the thermal de lead to the destruction of the catalyst or even damage or composition of methanol is counteracted by the fact destruction of the internal combustion engine and must that it takes place only at higher temperatures. This be prevented through the use of suitable catalysts. In means that the fuel or exhaust gas can only be incom some circumstances, this requires a toleration of levels pletely cooled. Furthermore, in some cases, the gases of carbon monoxide, methane and hydrogen in the fuel will not be hot enough to carry out the thermal decom gas produced which does not meet what are considered position of methanol.

as the most favorable combustion properties. 65 Thus, in another embodiment of the method the In view of these various problems, the need for an methanol is catalytically reacted with water in a re improved method of operating an internal combustion former heated by the fuel gas or exhaust gas. To carry fed with a reformed fuel gas becomes evident. out this catalytic reaction, catalysts normally used in the

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chemical industry for the synthesis of methanol under engine which is coupled to the output line 109 of the high pressure used. The same catalyst will result in the reformed gas generator 102 through apparatus to be endothermic decomposition of the methanol into CO more fully described below. Within the reformed gas and Hat low pressure. These processes also take place generator 102 the hydrocarbon fuel and oxygen con at lower temperature and can be used for cooling pur taining gas are converted into a fuel gas mixture con poses due to their heat demand. taining substantially carbon monoxide, carbon dioxide, When using such a method it is to advantage that the methane and/or hydrogen. This gas mixture flows out methanol and water be conducted into the methanol of the reformed gas generator through line 109 to a reformer with fuel gas and that the gas mixture pro cooler 105 from which it is supplied to the engine duced therein be fed to the internal combustion engine. 10 through a mixing device 106 where it is mixed with In such a case the methanol reformer will be directly additional combustion air drawn in over the line 107. In heated by the fuel gas which is fed into it from the accordance with the present invention, methanol is reformed gas generator. It is, however, also possible to sprayed into the line 109 from the line 108. The metha heat the reaction chamber from the outside using the nol sprayed into the line 109 is thermally decomposed hot fuel gases from the reformed gas generator. The 15 by the hot fuel gas coming out of the reformed genera reaction chamber of the methanol reformer can also be tor 102. It is thermally decomposed into hydrogen and heated from the outside using hot exhaust gases from carbon monoxide in the manner described above, at the the internal combustion engine. This last possibility is same time cooling the fuel gas. A portion of the gas preferably over the direct heating by the fuel gas from mixture which results from this decomposition and the the reformed gas generator where the operation of the 20 mixing of the decomposition products with the re methanol reformer would be disturbed by large quanti formed fuel gas is fed back over the line 110 to the inlet ties of fuel flowing through it. of the reformed gas generator 102. The remainder is fed Heating by the fuel gas is indicated in those cases through the cooler 105 to the internal combustion en where cooling the fuel gas is important. On the other gine 101. For control of the amount of the mixture hand, since the exhaust gases of the internal combustion 25 which is fed back, a metering valve is provided. engine generally have a higher temperature than the In addition, a compressor 112 is arranged in the re gases generated in the reformed gas generator, a metha turn line 110. This can be an exhaust gas turbo charger nol reformer heated by exhaust gas is advisable if the of a type well known in the automotive art. In installa primary object is to utilize the waste heat of the internal tions where the gas which is drawn through the re combustion engine. In such embodiments a portion of 30 formed gas generator suffers only a small pressure loss the reformed gas from the methanol reformer can be it may also be possible to design the junction of the mixed with the fuel gas. By doing this a fuel gas with a feedback line 110 with the reformed gas generator 102 higher carbon monoxide and high hydrogen content as a steam jet suction pump. The air drawn in through and thus with a higher octane member and higher calo the air intake line 103 then produces the suction which rific value will be fed to the internal combustion engine. 35 acts as the driving medium necessary for returning the As with the previously mentioned embodiments it can gas mixture from the output of the reformed gas genera of advantage to feedback a portion of the gas mixture tor on line 109 through the feedback line 110. leaving the methanol reformer to the reformed gas In the manner described in the aforementioned appli generator. This improves the composition of gas leav cation, a portion of the exhaust gas can also be con ing the reformed gas generator and counteracts the ducted back to the air intake line 104 in order to supply potential danger of soot formation. the reformed gas generator with an air and exhaust Preferably the methanol and/or water being fed to mixture acting as the gas containing oxygen. Further the methanol reformer will be evaporated and pre more, the reformed gas generator 102 may be heated by heated through heat exchange with the exhaust of the the engine exhaust through the use of a heat exchanger. internal combustion engine or the hot gas coming from 45 The cooler 105 may also be used to advantage for evap the reformed gas generator. The heat which is con orating the hydrocarbon fuels supplied on the fuel line tained in the exhaust gas or is to be removed for cooling 104. These are measures known in the art and are not of the fuel gas will thereby be more fully utilized and, in illustrated or described in detail. Furthermore, to obtain addition, the reaction in the methanol reformer can be homogeneity of the mixture, the air and exhaust gas controlled better through the use of gaseous starting 50 mixture where used can be drawn into the inlet of the materials. reformed gas generator 102 through a mixer disposed at BRIEF DESCRIPTION OF THE DRAWINGS the input of the reformed gas generator prior to enter ing its reaction chamber. In conventional fashion, the

FIGS. 1-4 are schematic illustrations of four different reaction chamber will contain a catalyst applied, for arragnements for implementing the method of the pres 55 example, to sintered bodies or a catalyst in a bed of filler ent invention. material and at which the conversion of the gas mixture DETAILED DESCRIPTION OF THE into gas fuel gas takes place.

PREFERRED EMBODIMENT Further auxiliary devices such as, for example, com pressors or control units may also be advantageuous.

FIG. 1 illustrates a first embodiment for implement For example, supplemental heating means for warming ing the method of the present invention. An internal up and the quick starting of a cold installation may be combustion engine 101 is supplied with a reformed fuel installed along with means to evaporate the fuel in the gas from a reformed gas generator 102 of the type de line 104, control means being provided to inject the scribed in the aforementioned, copending applications. methanol and feedback exhaust gas only at a later time. Evaporated or atomized hydrocarbon fuel is supplied 65 Once again, the types of controls necessary to carry out over a line 104 and oxygen containing gas supplied over such functions are described in detail in the aforemen a line 103 to the reformed gas generator 102. These tioned specification. Furthermore, since a definite tem components are drawn in by the internal combustion perature range should be maintained in reformed gas

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generator 102 to maintain the catalytic reaction it may results in the use of the exhaust gas to atomize the me also be advantageous to control the quantity of the gas thonal and water before they enter the reformer 409. As which is to be introduced into the reformed gas genera with the embodiment of FIG. 3, a portion of the reac tor through the line 110. As noted above, this gas is tion products from the methonal reformer is fed back cooled by the decomposition of the methanol. Thus, over the line 410 to the inlet of the reformed gas genera control of this quantity as a function of temperature in tor 402 with the remainder fed over the line 411 to the the reaction chamber is desireable. cooler 405 where it is mixed with the reformed gas and FIG. 2 illustrates another embodiment for carrying fed to the internal combustion engine 401 after passing out the method of the present invention. The arrange through the mixer and being mixed with further com ment is essentially as shown on FIG. 1 with the internal O bustion air.

combustion engine 201 drawing in an oxygen contain It will be evident to those skilled in the art that vari ing gas over line 203, and a hydrocarbon fuel gas over ous modifications of the basic method other than those line 204 and additional combustion air over line 207, illustrated may be made. For example, it is possible in reformed fuel gas and the additional combustion air the embodiment of FIG. 4 to evaporate the methonal being mixed in the mixer 206. Once again, a reformed 15 and water in the heat exchanger 405 rather than in a gas generator 202 is interposed between the input lines separate heat exchanger 413. Furthermore, where the and the internal combustion engine. As in the previous fuel gas is to be used in gas turbines or in a stationary embodiment, a cooler 205 is provided. The main differ reciprocating engine where a poor filling factor can be ence in this embodiment is that, rather than spraying the tolerated, the cooling of the reformed fuel gas is unnec methanol directly into the line 109, a methanol reformer 20 essary. In the latter case the poor filling factor which 209 in series with the reformed gas generator 202 and occurs when hot fuel gas is used can be compensated by the cooler 205 is provided. The hot gases leaving the an increase in displacement volume. In such cases it is reformed gas generator 202 are fed directly into the advantageous to use the exhaust gas in the heat ex methonal reformer 209. The reformer contains a con changer for evaporating purposes and for heating the ventional catalyst and is heated by these hot fuel gases. 25 methonal reformer. This increases the efficiency of the A water and methonal mixture is sprayed into the me thonal reformer through the line 208. As an alternate, overall These apparatus by utilizing all of the exhaust gas heat.

and other modifications may be made without water and methonal can be injected through separate departing from the spirit of the invention which is in lines. The gas mixture produced by the catalytic decom tended to be limited position of the methonal is conducted partially into the 30 What is claimed is:solely by the appended claims. cooler 205 and partially into the reformed gas generator 1. A method of operating an internal combustion 202 through the line 210. The water and methonal can engine be injected in liquid form into the reformer 209 through reactionwith a fuel gas which is obtained by the catalytic of hydrocarbons and a gas containing oxygen the line 208 or can be first evaporated, for example, in in a reformed gas generator comprising the steps of: the cooler 205 through heat exchange with the fuel gas. 35 (a) endothermically converting methanol into a gas As an alternate, they can be vaporized through use of mixture containing carbon monoxide and hydrogen the exhaust gas from the internal combustion engine. utilizing the heat content of at least one of the FIG. 3 illustrates a further embodiment of the present group of gases consisting of the fuel gas from the invention. Once again, the same basic elements such as reformed gas generator and the exhaust gas from the internal combustion engine 301, hydrocarbon fuel the internal combustion engine to thereby convert gas supply line 304, oxygen containing gas line 303, that heat content to useable chemical energy; reformed gas generator 302, combustion air inlet 307 (b) mixing said gas mixture with at least one of the and mixer 306 are provided. The significant difference group consisting of the hydrocarbons and the fuel in this emboidment is that the cooler is eliminated and the methonal reformer 309 has the hot fuel gases from 45 gas; and the reformed gas generator passing therethrough to (c) feeding the gas mixture along with the fuel gas and supply heat but in a manner such that it is not in contact combustion air to the internal combustion engine with the gases in the methonal reformer. Methanol and for combustion therein.

water are supplied to the methonal reformer 309 over 2. The method according to claim 1 wherein said step the line 308. After conversion therein through a cata 50 of converting is carried out utilizing the heat content of lytic reaction with the catalyst heated by the hot fuel the exhaust gas from the internal combustion engine. gases, the resulting mixture is partially fed back over the 3. The method according to claim 1 wherein said step line 310 to the inlet to the reformed gas generator 302 of converting is carried out utilizing the heat content of with the remainder fed over line 311 to the inlet line 306 the fuel gas from the reformed gas generator. containing the reformed fuel gas. 55 4. The method according to claim 1 wherein said step The arrangement shown in FIG. 4 again has the same of mixing comprises mixing the gas mixture with the basic elements as in FIG.1. These include the hydrocar fuel gas and further including the step of feeding a por bon fuel inlet 404, oxygen containing gas inlet line 403, tion of the fuel gas mixed with the gas mixture back into reformed gas generator 402, cooler 405, mixer 406, and the reformed gas generator.

internal combustion engine 401. In this embodiment the 5. The method according to claim 1 wherein said step methonal reformer is heated by the exhaust gas from the of endothermically converting is a step of thermal de internal combustion engine rather than by the fuel gas composition.

from the reformed gas generator. Thus, the exhaust gas 6. The method according to claim 5 wherein said line 412 of the internal combustion engine is coupled to methanol which is to be decomposed is sprayed into the the methonal reformer 409 to heat the catalyst therein. 65 hot fuel gas coming from the reformed gas generator. Methonal and water are supplied to the methonal re 7. The method according to claim 5 and further in former through an additional heat exchanger 413 also cluding the steps of evaporating the methanol prior to coupled to a branch of the exhaust gas line 412. This decomposition.

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8. The method according to claim 7 wherein said step in the methanol reformer with the fuel gas from said of evaporating the methanol comprises evaporating reformed gas generator. w through a heat exchange with the exhaust gas of the 15. The method according to claim 13 wherein a internal combustion engine. O portion of the gas mixture formed in the methanol re 9. The method according to claim 7 wherein said step former is conducted back to the reformed gas genera of evaporating comprises evaporating through a heat tor.

exchange with the fuel gas being fed to the internal 16. The method according to claim 10 wherein said combustion engine. methanol reformer is heated from the outside by the hot 10. The method according to claim 1 wherein said 10 fuel gas from said reformed gas generator. step of endothermic conversion is a step of catalytically. 17. The method according to claim 16 wherein a reacting methanol and water in a reformer which is portion of the gas mixture formed in the methanol re heated. former is conducted back to the reformed gas genera 11. The method according to claim 10 wherein said tor.18. The method according to claim 16 and further methanol and water are supplied to said methanol re 15 including the step of mixing a portion of the gas formed former mixed with the hot fuel gas from said reformed in the methanol reformer with the fuel gas from said gas generator and the gas mixture produced in said reformed gas generator.

methanol reformer is fed to the internal combustion engine. 19. The method according to claim 18 wherein a 12. The method according to claim 10 wherein a 20 formerportion of the gas mixiture formed in the methanol re portion of the gas mixture formed in the methanol re tOr. is conducted back to the reformed gas genera former is conducted back to the reformed gas genera 20. The method according to claim 10 and further tor.

including the step of preheating at least one of the meth 13. The method according to claim 10 wherein the anol and water fed to said methanol reformer. reaction of the methanol reformer is heated from the 25 21. The method according to claim 20 wherein said outside by the hot exhaust gases from the internal com step of preheating is carried out through a heat ex bustion engine. change with the exhaust of the internal combustion 14. The method according to claim 13 and further engine.

including the step of mixing a portion of the gas formed k k is