JP2010077817A - Hydrogen mixed combustion engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive hydrogen mixed combustion engine system with emissions of carbon dioxide extremely reduced. <P>SOLUTION: The hydrogen mixed combustion engine system includes: an engine 1; a fuel tank 2 storing fuel for the engine; a dehydrogenation reactor 3 producing hydrogen by dehydrogenation reaction with a hydrogenated aromatic compound; a pressure maintaining means maintaining pressure in the dehydrogenation reactor 3 to 0.2 MPa or higher; a material tank 4 storing the hydrogenated aromatic compound; a hydrogen buffer tank 6 temporarily storing hydrogen extracted from the dehydrogenation reactor 3; a dehydrogenation reaction product tank 7 storing an aromatic compound; and a liquid level control device 15 controlling the liquid level of the aromatic component accumulated in the lower space 3b of the dehydrogenation reactor 3. The dehydrogenation reactor 3 is a shell and tube type reactor, a dehydrogenation catalyst 8 is filled into a tube 12, and exhaust gas delivered from the engine 1 is led to flow into a shell 11, thereby heating the catalyst 8. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hydrogen co-firing engine system using hydrogen as a part of fuel, and more particularly to a hydrogen co-firing engine system including a dehydrogenation reactor that produces hydrogen by dehydrogenation of a hydrogenated aromatic compound.

  Automobiles using fuel cells have been developed as one of the countermeasures against global warming. However, since the fuel cell system is very expensive, many technical problems still remain to spread. On the other hand, carbon dioxide emission standards required for automobiles are strict, and it is said that in 2025, the amount of carbon dioxide emission per 1 km traveling in 10.15 mode will be regulated to 70 g or less. A fuel cell is a system that discharges only water and is effective as a global warming countermeasure. However, it is very expensive, so it is also required to develop a new engine system that can reduce CO2 emissions at a realistic cost. .

  For example, Patent Document 1 discloses a hydrogen-using internal combustion engine that uses hydrogen produced by dehydrogenating a hydrogenated fuel such as so-called organic hydride and a dehydrogenated product as fuel. In order to make the dehydrogenation product a part of the fuel for the internal combustion engine, it is necessary to use a hydrogenation reaction product of gasoline as the hydrogenation fuel. Since gasoline usually contains about 40% of toluene, the hydrogenated fuel contains about 40% of methylcyclohexane as its organic hydride. As a result, since the mixing ratio of hydrogen and the dehydrogenation product (in this case, fuel equivalent to ordinary gasoline) cannot be set arbitrarily, there is a problem that the effect of reducing carbon dioxide emissions is limited. Was.

  Patent Document 2 discloses a hydrogen engine driven by only hydrogen, and a system for causing dehydration reaction of organic hydride using the engine exhaust heat. According to this system, like a fuel cell, in principle, no carbon dioxide gas is generated, but it is essential to develop an engine driven only by hydrogen. Such a hydrogen engine is considered to be a technology that can be realized particularly in consumer applications such as automobiles because the engine system is considered to be very expensive like a fuel cell vehicle.

  Further, Patent Document 3 discloses a hydrogen supply apparatus and a hydrogen supply method in which the pressure during fuel injection is 2 to 20 atm, the pressure during hydrogen generation is 5 to 300 atm, and the pressure during exhaust is atmospheric pressure to 0.01 atm. Has been. The purpose of changing the pressure is to regenerate the catalyst activity by desorbing the dehydride adsorbed on the catalyst surface, which causes the catalyst activity to decrease. However, since the reaction is carried out by greatly changing the pressure, there is a problem that the power consumed by the pressure increase / decrease operation is large and the carbon dioxide emission amount associated therewith is large.

Further, Patent Document 4 discloses that the dehydration reaction of organic hydride is carried out in a high-pressure reactor in the presence of a catalyst, and the hydrogen partial pressure in the reactor is reduced, thereby improving the chemical equilibrium of the dehydrogenation reaction. An apparatus and method for producing hydrogen in excess yield is disclosed. This apparatus is superior in that it does not require a variable operation such as pressure unlike the apparatus disclosed in Patent Document 3. However, this apparatus is a technique for large facilities such as a hydrogen station, and no mention is made of a method for supplying thermal energy necessary for the dehydrogenation reaction.
Japanese Patent Laying-Open No. 2005-147124 JP 2008-88922 A JP 2006-248814 A JP 2007-169072 A

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide an inexpensive hydrogen-mixed combustion engine system that emits very little carbon dioxide and is inexpensive.

  In order to solve the above problems, the present invention has the following configuration. That is, the hydrogen co-firing engine system according to claim 1 according to the present invention includes an engine that uses hydrogen as a part of fuel and a dehydrogenation reaction that generates hydrogen and an aromatic compound from a hydrogenated aromatic compound. A dehydrogenation reactor for producing hydrogen to be supplied to the engine by utilizing sensible heat of gas, pressure holding means for maintaining the pressure in the dehydrogenation reactor at 0.2 MPa or more, and the dehydration Hydrogen partial pressure reducing means for extracting hydrogen generated by an elementary reaction from the dehydrogenation reactor and reducing the hydrogen partial pressure in the dehydrogenation reactor.

  The hydrogen co-firing engine system according to claim 2 according to the present invention includes an engine that uses hydrogen as a part of fuel, and a catalyst for a dehydrogenation reaction that generates hydrogen and an aromatic compound from a hydrogenated aromatic compound, Performing the dehydrogenation reaction using sensible heat of the exhaust gas of the engine to produce hydrogen to be supplied to the engine, and maintaining the pressure in the dehydrogenation reactor at 0.2 MPa or more Pressure holding means, raw material supply means for supplying the hydrogenated aromatic compound as a raw material to the catalyst in the dehydrogenation reactor, and hydrogen generated by the dehydrogenation reaction is extracted from the dehydrogenation reactor. A hydrogen partial pressure lowering means for lowering the hydrogen partial pressure in the dehydrogenation reactor, and a liquid produced by the dehydrogenation reaction and dropped downward from the catalyst and collected in a lower space of the dehydrogenation reactor Liquid level control means for controlling the liquid level of the aromatic compound to a predetermined level, and aromatic compound extraction means for extracting the liquid aromatic compound from the dehydrogenation reactor. It is characterized by.

  Furthermore, the hydrogen co-firing engine system according to claim 3 according to the present invention is the hydrogen co-firing engine system according to claim 2, wherein the catalyst is continuously arranged in a flow path extending substantially along the direction of gravity. The hydrogenated aromatic compound supplied to the upper end of the flow path by the raw material supply means undergoes the dehydrogenation reaction while flowing in the flow path from the upper side to the lower side, and the dehydrogenation reaction is performed. The liquid aromatic compound generated by the reaction falls downward from the lower end portion of the flow path, and the hydrogen generated by the dehydrogenation reaction also forms the hydrogen content from the vicinity of the upper end portion of the flow path. It is characterized by being extracted by the pressure reducing means.

  Furthermore, the hydrogen co-firing engine system according to claim 4 according to the present invention is the hydrogen co-firing engine system according to claim 2 or 3, wherein the pressure holding means is installed in the hydrogen partial pressure reducing means. A pressure control device that adjusts the pressure in the reactor, a first electromagnetic valve that is installed in the raw material supply means and controls the amount of the hydrogenated aromatic compound supplied to the catalyst, and the aromatic compound extraction means A second electromagnetic valve that controls the amount of the aromatic compound that is installed and withdrawn from the dehydrogenation reactor; and an electromagnetic valve opening / closing means that opens and closes both the electromagnetic valves based on the output of the engine It is characterized by being.

  Furthermore, the hydrogen co-firing engine system according to claim 5 of the present invention is the hydrogen co-firing engine system according to any one of claims 1 to 4, wherein the hydrogenated aromatic compound is cyclohexane, methylcyclohexane, dimethyl. It is characterized by being at least one of cyclohexane, ethylcyclohexane, decalin, methyldecalin, dimethyldecalin, tetralin, methyltetralin, and dimethyltetralin.

  Furthermore, the hydrogen co-firing engine system according to claim 6 according to the present invention is the hydrogen co-firing engine system according to any one of claims 1 to 5, wherein the pressure holding means controls the pressure in the dehydrogenation reactor. It is characterized by being held at 0.5 MPa or more and 5 MPa or less.

  According to the hydrogen co-firing engine system of the present invention, hydrogen can be produced in a yield exceeding the chemical equilibrium of the dehydrogenation reaction by reducing the hydrogen partial pressure in the dehydrogenation reactor. The hydrogen can be mixed and supplied to the engine at an arbitrary ratio. Therefore, the hydrogen co-firing engine system of the present invention has very low carbon dioxide emission in addition to being inexpensive.

  In addition, if high-pressure hydrogen generated by the dehydrogenation reaction is supplied to the engine, it is not necessary to increase the pressure of the hydrogen when supplying the engine, and the thermal energy required for the dehydrogenation reaction depends on the sensible heat of the engine exhaust gas. Because it is supplied, there are few factors that reduce the energy efficiency of the engine system. Therefore, the hydrogen mixed combustion engine system of the present invention is excellent in energy efficiency.

Embodiments of a hydrogen co-firing engine system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram illustrating the configuration of the hydrogen co-firing engine system of the present embodiment, and FIG. 2 is a horizontal sectional view illustrating the internal structure of the dehydrogenation reactor.
The hydrogen co-firing engine system in FIG. 1 is a dehydration that produces hydrogen by dehydrogenation of an engine 1, a fuel tank 2 that stores general engine fuel such as gasoline and light oil, and a hydrogenated aromatic compound that is a raw material. An elementary reactor 3, a raw material tank 4 for storing a hydrogenated aromatic compound to be supplied to the dehydrogenation reactor 3, a hydrogen buffer tank 6 for temporarily containing hydrogen extracted from the dehydrogenation reactor 3, and a dehydrogenation And a dehydrogenation reaction product tank 7 for containing an aromatic compound generated together with hydrogen from a hydrogenated aromatic compound by the reaction.

A dehydrogenation catalyst 8 is provided in the dehydrogenation reactor 3, and a hydrogenated aromatic compound is supplied to the catalyst 8. Further, the catalyst 8 is heated to a high temperature by the sensible heat of the exhaust gas discharged from the engine 1.
The configuration of the dehydrogenation reactor 3 is not particularly limited, but is preferably a shell and tube type reactor. That is, as shown in FIG. 2, a large number of tubes 12 (corresponding to flow paths which are constituent elements of the present invention) extending along the direction of gravity (the axial direction of the shell 11) are arranged in a cylindrical shell 11. The catalyst 8 is filled in these tubes 12.

  The hydrogenated aromatic compound flows in the gravity direction from the upper side toward the lower side while contacting the catalyst 8 while the hot aromatic gas exhausted from the engine 1 flows into the shell 11 (that is, the tube 12). The catalyst 8 in the tube 12 is heated. In addition, you may provide a fin etc. in the outer surface of the tube 12 so that the efficiency of heat exchange with exhaust gas may become high. The flow direction of the exhaust gas in the shell 11 is not particularly limited. However, since the dehydrogenation reaction is an endothermic reaction, the flow direction may be opposite to the flow direction of the hydrogenated aromatic compound in the tube 12. preferable.

  As shown in FIG. 1, such a shell 11 is installed in a substantially middle position in the vertical direction inside the dehydrogenation reactor 3, and the shell 11 forms two internal spaces in the dehydrogenation reactor 3. It is divided into two. Then, the hydrogen generated by the dehydrogenation is ejected from the opening at the upper end of the tube 12 and is stored in the upper space 3a located on the upper side of the shell 11, and the liquid aroma generated by the dehydrogenation is also used. The group compound falls downward from the opening at the lower end of the tube 12 and is stored in the lower space 3b located on the lower side of the shell 11.

  The dehydrogenation reactor 3 has a liquid level control device 15 for controlling the liquid level of the liquid aromatic compound accumulated in the lower space 3b to a predetermined level (the liquid level that is a constituent of the present invention). Corresponding to the control means) is installed. By the hydrogenated aromatic compound flowing in the tube 12 from the upper side to the lower side and the liquid level of the aromatic compound being controlled, the generated hydrogen flows upward in the tube 12 and the dehydrogenation reactor. Since the hydrogen partial pressure in 3 becomes low, hydrogen is generated in a yield exceeding the chemical equilibrium.

  The aromatic compound accumulated in the lower space 3b also functions as a seal that prevents hydrogen gas from leaking from the dehydrogenation reactor 3 through a pipe 27 described later, but the liquid level of the aromatic compound is low. If it is too high, the sealing function will be insufficient and hydrogen gas may leak from the dehydrogenation reactor 3. On the other hand, if the liquid level of the aromatic compound is too high and comes into contact with the catalyst 8, the dehydrogenation reaction may be adversely affected. For this reason, a suitable liquid level is maintained by the liquid level control device 15.

The liquid level control device 15 is not particularly limited as long as it is designed to operate stably according to the dehydrogenation reaction conditions, and the liquid level control method is not particularly limited. For example, a capacitance type control device, a float type control device, various sensors using light, or a sensor using ultrasonic waves may be used.
The liquid level control device 15 is designed to control the liquid level based on the output of the engine 1 and the output of a high-pressure pump 22 described later that pressurizes the hydrogenated aromatic compound. preferable.

Here, the operation of the hydrogen mixed combustion engine system of the present embodiment as described above will be described in detail.
The hydrogenated aromatic compound stored in the raw material tank 4 is sent through the pipe 21 to the dehydrogenation reactor 3 whose inside is maintained at a high pressure. At this time, the supply amount of the hydrogenated aromatic compound is controlled by the electromagnetic valve 23. In addition, the hydrogenated aromatic compound is sent in a pressurized state so that it can be supplied into the high-pressure dehydrogenation reactor 3, but the hydrogenated aromatic compound is a liquid, so that it is different from the case of gas. The high pressure pump 22 can easily pressurize with less energy. After the hydrogenated aromatic compound is supplied to the upper space 3 a of the dehydrogenation reactor 3, it flows from the opening at the upper end of the tube 12 and flows downward in the tube 12 while contacting the catalyst 8. In addition, the raw material tank 4 and the piping 21 correspond to the raw material supply means which is a component of the present invention, and the electromagnetic valve 23 corresponds to the first electromagnetic valve which is a component of the present invention.

  On the other hand, since the high-temperature exhaust gas discharged from the engine 1 is always sent into the shell 11 through the pipe 25, the catalyst 8 in the tube 12 is heated to a high temperature by the sensible heat of the exhaust gas. . Therefore, the dehydrogenation reaction of the hydrogenated aromatic compound proceeds smoothly in the tube 12, and hydrogen and the aromatic compound are generated. For example, when the hydrogenated aromatic compound is methylcyclohexane, hydrogen and toluene are produced. When the hydrogenated aromatic compound is decalin, hydrogen, naphthalene and a small amount of tetralin are generated.

  The hydrogen gas generated in the tube 12 moves upward by buoyancy, is ejected from the opening at the upper end of the tube 12, and is stored in the upper space 3 a of the dehydrogenation reactor 3. The pressure in the dehydrogenation reactor 3 is maintained at a high pressure by the generated hydrogen. Similarly, since the aromatic compound produced by the dehydrogenation reaction is liquid at the temperature and pressure in the dehydrogenation reactor 3, it moves downward in the tube 12 and opens from the opening at the lower end. It falls downward and is stored in the lower space 3 b of the dehydrogenation reactor 3.

  That is, since the hydrogen and the aromatic compound, which are products of the dehydrogenation reaction, are gas and liquid, they are separated in the dehydrogenation reactor 3 without using a separation membrane or the like and held in separate spaces. Note that the aromatic compound stored in the lower space 3b of the dehydrogenation reactor 3 may contain unreacted hydrogenated aromatic compound. In addition, it may contain reaction byproducts of the dehydrogenation reaction and other impurities.

  Since the pipe 26 is connected to the upper space 3 a of the dehydrogenation reactor 3, hydrogen is extracted from the upper space 3 a of the dehydrogenation reactor 3 through the pipe 26, and a hydrogen buffer tank provided in the middle of the pipe 26 6 (the pipe 26 corresponds to a hydrogen partial pressure lowering means which is a constituent of the present invention). Thereby, the hydrogen partial pressure in the dehydrogenation reactor 3 decreases. Then, since the equilibrium state of the dehydrogenation reaction is lost, the dehydrogenation reaction of the hydrogenated aromatic compound further proceeds, and hydrogen can be generated at a high reaction rate exceeding the chemical equilibrium. Note that the hydrogen buffer tank 6 may not be provided.

  In the dehydrogenation reaction of a hydrogenated aromatic compound, the reaction rate tends to be slowed as the dehydrogenation reaction proceeds. Therefore, particularly in the latter stage of the dehydrogenation reaction, the hydrogen partial pressure in the dehydrogenation reactor 3 is reduced. By doing so, a higher reaction rate can be achieved. For example, in the case of decalin, the reaction proceeds relatively easily until three molecules of hydrogen are dehydrogenated to tetralin, but the reaction of further dehydrogenating two molecules of hydrogen to naphthalene is relatively difficult to proceed. Therefore, in order to dehydrogenate two molecules of hydrogen from tetralin to naphthalene, it is very effective to reduce the hydrogen partial pressure.

  Further, in the dehydrogenation reactor 3 of the present embodiment in which the dehydrogenation reaction proceeds while the hydrogenated aromatic compound flows downward in the tube 12, the latter stage of the dehydrogenation reaction such as dehydrogenation from tetralin to naphthalene. The region reaction often proceeds in the lower portion of the tube 12. Since hydrogen gas moves to the upper side of the tube 12 by buoyancy, the hydrogen partial pressure is likely to be significantly reduced in the lower portion of the tube 12 where the reaction in the latter region occurs, thereby achieving a high reaction rate. That is, the hydrogenated aromatic compound as a raw material is preferably reacted while flowing downward. Further, it is more preferable that hydrogen is extracted from approximately the middle in the vertical direction of the tube 12, more preferably from the vicinity of the upper end of the tube 12, and in the vicinity of the approximately middle of the tube 12 and the upper end. It is particularly preferred to extract from both.

  The lower space 3b of the dehydrogenation reactor 3 and the dehydrogenation reaction product tank 7 are communicated with each other by a pipe 27 corresponding to an aromatic compound extraction means that is a constituent element of the present invention. The aromatic compound stored in the lower space 3b of the dehydrogenation reactor 3 is extracted by the pipe 27 while the extraction amount is controlled by the electromagnetic valve 28 (corresponding to the second electromagnetic valve which is a constituent element of the present invention). The dehydrogenation reaction product tank 7 is accommodated.

  On the other hand, the hydrogen extracted from the upper space 3a of the dehydrogenation reactor 3 is sent to and stored in the hydrogen buffer tank 6 through the pipe 26 as described above. Since the dehydrogenation reactor 3 has a high pressure, the hydrogen in the dehydrogenation reactor 3 is also at a high pressure, and the hydrogen in the hydrogen buffer tank 6 sent from the dehydrogenation reactor 3 as it is is also in a high pressure (dehydrogenation reactor 3 and the same pressure).

  The hydrogen in the hydrogen buffer tank 6 is adjusted in pressure by a pressure adjusting valve 29 (for example, a back pressure valve) corresponding to a pressure control device which is a constituent element of the present invention, and supplied to the engine 1 through a pipe 30 connected to the pipe 26. The At this time, general engine fuel such as gasoline and light oil supplied from the fuel tank 2, air, and hydrogen are appropriately mixed in the middle of the pipe 30 and supplied to the engine 1.

Since the pressure in the dehydrogenation reactor 3 needs to be maintained at a high pressure, the hydrogen co-firing engine system of the present embodiment includes a pressure maintaining means for maintaining the pressure in the dehydrogenation reactor 3 at a high pressure. .
This pressure holding means adjusts the pressure of hydrogen in the hydrogen buffer tank 6 (that is, the pressure in the dehydrogenation reactor 3 communicating with the hydrogen buffer tank 6 is also adjusted by the pressure adjustment valve 29). An electromagnetic valve 23 for controlling the amount of the hydrogenated aromatic compound supplied to the catalyst 8, an electromagnetic valve 28 for controlling the amount of the aromatic compound extracted from the dehydrogenation reactor 3, and the output of the engine 1. And solenoid valve opening / closing means (not shown) for opening and closing both solenoid valves 23 and 28 based on the above.

  When the pressure in the dehydrogenation reactor 3 is set to a high pressure, the pressure regulating valve 29 and both electromagnetic valves 23 and 28 are closed, and the pressure in the dehydrogenation reactor 3 is maintained at a high pressure. When hydrogen is supplied from the buffer tank 6 to the engine 1 and the pressure in the dehydrogenation reactor 3 is reduced, the electromagnetic valve 23 is opened to produce hydrogen gas by the dehydrogenation reaction. The valve 28 is opened and the aromatic compound is extracted. Further, when the engine 1 is stopped, both electromagnetic valves 23 and 28 are closed, and the dehydrogenation reaction is stopped. As described above, the opening and closing of both solenoid valves 23 and 28 is determined by the driving condition of the engine 1, so that the solenoid valve opening and closing means (not shown) controls the opening and closing of both solenoid valves 23 and 28 based on the output of the engine 1. It has become.

  However, in the hydrogen co-firing engine system immediately after manufacture and before use (for example, at the time of shipment or installation to the engine), the hydrogen is filled in the dehydrogenation reactor 3 to increase the pressure and the solenoid valves 23 and 28 are closed. The pressure needs to be maintained. This operation is required only once at the time of shipment or attachment to the engine. Thereafter, the high pressure is maintained by the hydrogen generated by the dehydrogenation reaction. Further, since the pressure in the dehydrogenation reactor 3 does not need to be variably controlled, the pressure regulating valve 29 does not have to be capable of being automatically controlled to an arbitrary pressure, but is not limited at all.

Since such a hydrogen co-firing engine system of this embodiment includes the dehydrogenation reactor 3, it can be mounted on an automobile, train, ship, aircraft, etc. and operated while generating hydrogen on-board. .
Further, in such a hydrogen mixed combustion engine system of the present embodiment, the engine fuel and hydrogen can be mixed at an arbitrary ratio and supplied to the engine. Therefore, since an existing general engine (for example, a gasoline engine or a diesel engine) can be used as the engine 1, the engine system is inexpensive. Furthermore, the amount of fuel used for an engine can be reduced by mixing hydrogen with a general engine.

  Furthermore, such a hydrogen co-firing engine system of the present embodiment can be operated at a high air-fuel ratio that cannot be achieved by a normal engine by co-firing engine fuel and hydrogen. A significant reduction in carbon dioxide emissions is achieved. For example, when a general gasoline engine is used as the engine 1, the air-fuel ratio can be about 25, the fuel consumption is improved by about 30%, and the carbon dioxide emission is reduced by about 30%.

  Furthermore, if high-pressure hydrogen in the hydrogen buffer tank 6 is supplied to the engine 1, it is not necessary to increase the pressure of hydrogen when supplying the hydrogen to the engine 1. Therefore, the hydrogen co-firing engine system of the present embodiment is excellent in energy efficiency because there are few factors that reduce energy efficiency. Furthermore, in the hydrogen co-fired engine system of the present embodiment, thermal energy necessary for the dehydrogenation reaction is supplied by sensible heat of the exhaust gas of the engine 1. For example, the temperature of exhaust gas discharged from an internal combustion engine such as a gasoline engine is a high temperature of 500 ° C. or higher, so that the temperature of the catalyst 8 can be stably maintained at 250 ° C. or higher necessary for the dehydrogenation reaction. As a result, it is not necessary to provide a separate heat source, the overall hydrogen mixed combustion engine system can be reduced in size and weight, and the energy efficiency of the engine system can be increased.

  In addition, although the pressure in the dehydrogenation reactor 3 needs to be hold | maintained at the high pressure by the said pressure holding means, the pressure needs to be 0.2 Mpa or more. If the pressure is less than 0.2 MPa, it is difficult to supply the produced hydrogen as it is to the engine 1 without increasing the pressure, and it becomes necessary to separately increase the pressure before supplying the hydrogen to the engine 1. In addition, if it is less than 0.2 MPa, the aromatic compound produced by the dehydrogenation reaction may not become liquid but gaseous in the dehydrogenation reactor 3, so that it is not separated from hydrogen. It will occur. In order to make such inconvenience difficult to occur, the pressure in the dehydrogenation reactor 3 is preferably 0.5 MPa or more. On the other hand, if the pressure in the dehydrogenation reactor 3 exceeds 5 MPa, the reaction rate of the dehydrogenation reaction is reduced, and the hydrogen yield may be reduced.

  The hydrogenated aromatic compound is a compound obtained by hydrogenating an aromatic compound, and a saturated hydrocarbon compound is preferable. A hydrogenated aromatic compound produces | generates hydrogen by a dehydrogenation reaction, and produces | generates an aromatic compound. Specific examples of the hydrogenated aromatic compound include cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, decalin, methyldecalin, dimethyldecalin, tetralin, methyltetralin, and dimethyltetralin.

  Among these hydrogenated aromatic compounds, when using hydrides of monocyclic compounds such as benzene and toluene (that is, cyclohexane, methylcyclohexane, etc.), the dehydrogenation reaction should be performed at a temperature of about 300 to 350 ° C. However, when a hydride of a bicyclic compound such as naphthalene (that is, decalin or the like) is used, the dehydrogenation reaction is preferably performed at a temperature of about 350 to 400 ° C.

  Below the lower limit of the above temperature range, the reaction rate of the dehydrogenation reaction is slow, which is not realistic. On the other hand, if the upper limit of the temperature range is exceeded, the reaction rate of the dehydrogenation reaction is high, but carbon is deposited on the catalyst 8 and the catalyst life is shortened, which is not preferable. Since the temperature range suitable for the dehydrogenation reaction differs depending on the type of hydrogenated aromatic compound, the selection of the hydrogenated aromatic compound to be used in the hydrogen co-firing engine system should be determined by the nature of the engine exhaust gas that is the heat source. Is preferred.

  Furthermore, the kind of the catalyst 8 is not particularly limited, and any catalyst that is known as a catalyst for the dehydrogenation reaction can be used without any problem. For example, a catalyst containing at least one metal selected from the group consisting of palladium, platinum, rhodium, iridium, ruthenium, osmium, molybdenum, rhenium, tungsten, vanadium, nickel, chromium, cobalt, and iron can be used.

  These metals can be used in a non-supported state like nickel sponge, but since the higher thermal conductivity of the catalyst is advantageous for the dehydrogenation reaction, it is preferable to use the metal supported on the catalyst carrier. More preferred. Examples of the catalyst carrier include alumina, silica, zirconia, zeolite, titania, activated carbon, diatomaceous earth, and the like, but metallic ones are preferable. Examples of metallic catalyst carriers include metal honeycombs and metal sponges. For example, a catalyst in which platinum is supported as a catalyst species on these carriers is suitable as a catalyst. As a method for supporting a catalyst species such as platinum, any method such as an impregnation method or a dip coating method can be adopted.

It is a conceptual diagram explaining the structure of the hydrogen co-firing engine system of this embodiment. It is a horizontal sectional view explaining the internal structure of a dehydrogenation reactor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Fuel tank 3 Dehydrogenation reactor 3a Upper space 3b Lower space 4 Raw material tank 6 Hydrogen buffer tank 7 Dehydrogenation reaction product tank 8 Catalyst 11 Shell 12 Tube 15 Liquid level control device 21 Piping 22 High pressure pump 23 Electromagnetic valve 25 Piping 26 Piping 27 Piping 28 Solenoid valve 29 Pressure regulating valve

Claims (6)

An engine that uses hydrogen as part of the fuel;
A dehydrogenation reactor for producing hydrogen to be supplied to the engine by performing a dehydrogenation reaction for generating hydrogen and an aromatic compound from the hydrogenated aromatic compound by utilizing sensible heat of the exhaust gas of the engine;
Pressure holding means for holding the pressure in the dehydrogenation reactor at 0.2 MPa or more;
A hydrogen partial pressure lowering means for extracting hydrogen generated by the dehydrogenation reaction from the dehydrogenation reactor and reducing a hydrogen partial pressure in the dehydrogenation reactor;
A hydrogen co-firing engine system comprising: An engine that uses hydrogen as part of the fuel;
A catalyst for a dehydrogenation reaction that generates hydrogen and an aromatic compound from a hydrogenated aromatic compound, performs the dehydrogenation reaction using sensible heat of the exhaust gas of the engine, and supplies hydrogen to be supplied to the engine A dehydrogenation reactor to be produced;
Pressure holding means for holding the pressure in the dehydrogenation reactor at 0.2 MPa or more;
A raw material supply means for supplying the hydrogenated aromatic compound as a raw material to the catalyst in the dehydrogenation reactor;
A hydrogen partial pressure lowering means for extracting hydrogen generated by the dehydrogenation reaction from the dehydrogenation reactor and reducing a hydrogen partial pressure in the dehydrogenation reactor;
Liquid level control for controlling the liquid level of the liquid aromatic compound generated by the dehydrogenation reaction and falling downward from the catalyst and accumulated in the lower space of the dehydrogenation reactor to a predetermined level Means,
An aromatic compound extraction means for extracting the liquid aromatic compound from the dehydrogenation reactor;
A hydrogen co-firing engine system comprising:   The catalyst is continuously arranged in a flow path extending substantially along the direction of gravity, and the hydrogenated aromatic compound supplied to the upper end of the flow path by the raw material supply means is the flow The dehydrogenation reaction is performed while flowing from the upper side toward the lower side in the passage, and the liquid aromatic compound generated by the dehydrogenation falls downward from the lower end portion of the flow path. The hydrogen co-firing engine system according to claim 2, wherein the hydrogen generated by the dehydrogenation reaction is extracted by the hydrogen partial pressure reducing means from the vicinity of the upper end of the flow path.   The pressure holding unit is installed in the hydrogen partial pressure lowering unit and adjusts the pressure in the dehydrogenation reactor, and the hydrogenated aromatic compound installed in the raw material supply unit and supplied to the catalyst A first solenoid valve that controls the amount of the aromatic compound, a second solenoid valve that is installed in the aromatic compound extraction means and controls the amount of the aromatic compound extracted from the dehydrogenation reactor, and an output of the engine The hydrogen mixed combustion engine system according to claim 2 or 3, comprising: electromagnetic valve opening / closing means that opens and closes both electromagnetic valves based on the electromagnetic valve.   The hydrogenated aromatic compound is at least one of cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, decalin, methyldecalin, dimethyldecalin, tetralin, methyltetralin, and dimethyltetralin. Item 5. The hydrogen co-firing engine system according to any one of Items 1 to 4.   The hydrogen co-firing engine system according to any one of claims 1 to 5, wherein the pressure holding means holds the pressure in the dehydrogenation reactor at 0.5 MPa or more and 5 MPa or less.

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