JP2009085028A - Exhaust-gas reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust-gas reformer with a simple configuration, capable of more reliably reforming fuel for reforming and exhaust-gas. <P>SOLUTION: A CaO tank 35 that can supply CaO which performs an exothermal reaction by mixing with an exhaust gas, at an upstream side in a flow direction of the exhaust-gas of a reforming reaction section 32 for generating reformed gas by subjecting exhaust-gas and fuel for reforming to endoergic reaction. During operation of an internal combustion engine 1, CaO is supplied from the CaO tank 35 into a passage for reforming 22, and an exhaust gas which flows through the passage for reforming 22 and CaO are subjected to an exothermal reaction. Accordingly, the reforming reaction section 32 can be heated by utilizing reaction heat during the exothermal reaction between the exhaust-gas and the CaO, and reforming can be performed by subjecting the exhaust gas and the fuel for reforming to endoergic reaction more reliably. Further, as a means for heating the reforming reaction section 32, the reforming reaction section 32 can be heated with a simple configuration, because only the CaO tank 35 which mixes the exhaust gas with the CaO is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas reforming apparatus. In particular, the present invention relates to an exhaust gas reforming apparatus that generates reformed gas combustible in an internal combustion engine by flowing exhaust gas injected with fuel through a reforming catalyst.

  In a conventional internal combustion engine, fuel is burned in a combustion chamber, and a crankshaft is rotated by operating a piston located in a cylinder by a pressure when the fuel burns. Thereby, the conventional internal combustion engine takes out the thermal energy at the time of combustion of fuel as kinetic energy, and the exhaust gas after combustion of the fuel is discharged from the exhaust passage to the atmosphere. However, in such an internal combustion engine, heat energy is released to the outside as heat or sound, or mechanical loss occurs, so that heat energy can be used as kinetic energy for some of the heat energy. It has become. For this reason, although thermal efficiency is not so high, in some conventional internal combustion engines, the exhaust gas is effectively used to improve thermal efficiency.

  For example, the engine described in Patent Document 1 includes a heat exchanger that generates hot water and a fuel reformer that reforms fuel and exhaust gas. The fuel reformer generates heat from the hot water. By utilizing the endothermic reaction between the fuel and the exhaust gas, a reformed gas combustible in the cylinder is generated. The reformed gas generated in this way is supplied to the combustion chamber and burned in the combustion chamber, so that the heat energy can be chemically recovered and the exhaust gas can be reused, so that the thermal efficiency can be improved. it can.

Japanese Patent Laid-Open No. 2001-152846

  Some conventional internal combustion engines are designed to improve thermal efficiency by providing an exhaust gas reforming device having a fuel reforming device such as a reforming catalyst in the exhaust gas path. Such a fuel reformer reforms by endothermic reaction when reforming fuel and exhaust gas. For this reason, when reforming is performed by the fuel reformer, it is necessary to supply heat energy from the outside. As a supply source of thermal energy when reforming with a fuel reformer, an exhaust gas reformer provided in a conventional internal combustion engine uses the heat of exhaust gas discharged from the operating internal combustion engine, A heat exchanger that generates hot water is provided as in the engine described in Patent Document 1, and the heat of the hot water generated by this heat exchanger is used.

  However, the temperature of the exhaust gas changes according to the operating state of the internal combustion engine. On the other hand, when the fuel and the exhaust gas are reformed by an endothermic reaction in the fuel reformer, heat above a predetermined temperature is supplied. There is a need to. For this reason, depending on the operating state of the internal combustion engine, the exhaust temperature is too low, and it may be difficult to reform the fuel and the exhaust gas. Further, in order to stably supply heat energy to the fuel reformer, when a heat exchanger that generates hot water is provided like the engine described in Patent Document 1, the device may be complicated. There is a risk of increasing the manufacturing cost.

  The present invention has been made in view of the above, and it is an object of the present invention to provide an exhaust gas reforming apparatus capable of more reliably reforming reforming fuel and exhaust gas with a simple configuration. And

  In order to solve the above-described problems and achieve the object, an exhaust gas reforming apparatus according to the present invention is configured to perform endothermic reaction between exhaust gas exhausted from a cylinder of an internal combustion engine and reforming fuel. A reforming means for generating reformed gas containing combustible gas combustible in the interior, a recirculation passage through which at least the combustible gas can flow into the intake passage of the cylinder, and an exothermic reaction when mixed with the exhaust gas And a heating element mixing means capable of mixing the heating element with the exhaust gas upstream of the reforming means in the flow direction of the exhaust gas.

  In the present invention, the heating element mixing means capable of mixing the exhaust gas and the heating element is provided on the upstream side of the reforming means in the flow direction of the exhaust gas. For this reason, the exhaust gas and the heating element can be mixed on the upstream side of the reforming means, and the exhaust gas and the heating element can be reacted exothermically. As a result, the reforming means can be heated by using the reaction heat during the exothermic reaction between the exhaust gas and the heating element, and the exhaust gas and the reforming fuel can be subjected to an endothermic reaction more reliably. Further, since only the heating element mixing means for mixing the heating element with the exhaust gas is provided as means for heating the reforming means, the reforming means can be heated with a simple configuration. As a result, the reforming fuel and the exhaust gas can be more reliably reformed with a simple configuration.

  The exhaust gas reforming apparatus according to the present invention further comprises gas-solid separation means for separating a gas and a solid generated when the exhaust gas and the heating element are mixed. To do.

  In the present invention, since the gas-solid separation means is provided, the gas and solid generated by mixing the heating element with the exhaust gas can be separated, and only the gas can flow into the intake passage from the reflux passage. Thereby, it can suppress that the impurity unnecessary for combustion in a cylinder flows in in a cylinder. As a result, more stable combustion can be obtained.

  The exhaust gas reforming apparatus according to the present invention further separates the combustible gas from the reformed gas generated by the endothermic reaction of the exhaust gas and the reforming fuel by the reforming means. Combustible gas separation means is provided.

  In this invention, since the combustible gas separation means is provided, the combustible gas can be separated from the reformed gas generated by the reforming means, and only the combustible gas can flow into the intake passage from the recirculation passage. Thereby, it is possible to suppress a gas unnecessary for combustion in the cylinder from flowing into the cylinder. As a result, more stable combustion can be obtained.

  The exhaust gas reforming apparatus according to the present invention has an effect that the reforming fuel and the exhaust gas can be more reliably reformed with a simple configuration.

  Embodiments of an exhaust gas reforming apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same. In the following description, as an example of an internal combustion engine provided with an exhaust gas reformer, a case where the internal combustion engine is a gasoline engine that uses gasoline as fuel for operating the internal combustion engine will be described.

  FIG. 1 is an overall configuration diagram of an internal combustion engine including an exhaust gas reforming apparatus according to Embodiment 1 of the present invention. An exhaust gas reforming apparatus 3 shown in the figure is provided in an internal combustion engine 1 that is a vehicle (not shown) and that serves as a prime mover during operation of the vehicle. The internal combustion engine 1 includes four cylinders 5 arranged in series. The internal combustion engine 1 includes an intake passage 10 that is a passage that communicates with the cylinder 5 and flows air taken into the cylinder 5. After the fuel is burned in the cylinder 5, an exhaust passage 20 through which exhaust gas discharged from the cylinder 5 flows is connected. These intake passages 10 and exhaust passages 20 are branched into four passages according to the number of cylinders 5, and the branched passages correspond to the four cylinders 5 and communicate with each other in the cylinders 5. 1 is connected.

  Of the intake passage 10 and the exhaust passage 20, an intake passage 10 is provided with an injector 11 which is a fuel supply means capable of supplying fuel to the cylinder 5 during operation of the internal combustion engine 1. The injector 11 is provided so that fuel can be supplied to the cylinder 5 by injecting fuel into the cylinder 5 during operation of the internal combustion engine 1. A throttle valve 12 that can open and close the intake passage 10 is disposed upstream of the injector 11 in the flow direction of the air flowing through the intake passage 10, and the intake passage is further upstream of the throttle valve 12. An air flow meter 13 capable of detecting the flow rate of air flowing through the inside 10 is provided. An air cleaner 14 for removing impurities in the air flowing into the intake passage 10 is provided at the inlet of the intake passage 10 thus formed.

  The exhaust passage 20 is branched into two-way passages at predetermined positions, and one of the branched exhaust passages 20 is an exhaust main passage 21 that is a main passage of the exhaust passage 20. The other of the branched exhaust passages 20 is a reforming passage 22. Among these, the reforming passage 22 is provided with a reforming reaction layer 30 for reforming the exhaust gas. The reforming reaction layer 30 has a mixing portion 31 therein, and further the reforming reaction layer 30. The reforming reaction part 32 is internally provided. The positional relationship between the mixing unit 31 and the reforming reaction unit 32 is such that the mixing unit 31 is located upstream of the reforming reaction unit 32 in the flow direction of the exhaust gas flowing through the reforming reaction layer 30. Of the mixing unit 31 and the reforming reaction unit 32 thus provided, the mixing unit 31 is provided with a reforming fuel injector 25 that injects reforming fuel into the mixing unit 31.

Further, the reforming reaction section 32 causes an endothermic reaction between the exhaust gas discharged from the cylinder 5 of the internal combustion engine 1 and the reforming fuel that is fuel added to the exhaust gas when reforming the exhaust gas. Thus, it is provided as reforming means for generating reformed gas containing combustible gas combustible in the cylinder 5. The reforming reaction section 32 is formed in a so-called honeycomb shape in which a plurality of substantially hexagonal passages are formed, and a reforming catalyst (not shown) made of, for example, a rhodium catalyst is formed on the surface of the passage. Is coated. Thus, the reforming reaction section 32 can generate the reformed gas by coating the reforming catalyst. Further, when the reforming gas is generated in the reforming reaction section 32, the reformed gas containing H ₂ (hydrogen) that is a combustible gas combustible in the cylinder 5 of the internal combustion engine 1 is generated.

  Further, in the reforming passage 22 located upstream of the reforming reaction layer 30 in the exhaust gas flow direction, CaO (calcium oxide), which is a heating element that reacts exothermically when mixed with the exhaust gas, is modified. A CaO tank 35 which is a heating element mixing means capable of mixing with the exhaust gas flowing in the quality passage 22 is provided. That is, the CaO tank 35 is provided on the upstream side of the reforming reaction section 32 in the flow direction of the exhaust gas flowing through the reforming passage 22 so that CaO can be mixed with the exhaust gas. The CaO tank 35 is formed so as to be able to store CaO, and is provided so as to be able to supply CaO to the reforming passage 22 with an arbitrary supply amount.

  Further, on the downstream side of the reforming reaction layer 30 in the flow direction of the exhaust gas flowing through the reforming passage 22, a gas generated when the exhaust gas and CaO are mixed, and a solid powder that is a particulate solid A gas-solid separation device 36 is provided as gas-solid separation means for separating the two. That is, the gas-solid separation device 36 is provided so as to be able to separate the reformed gas and the solid powder. The gas-solid separation device 36 is provided with a filter (not shown) having innumerable pores smaller than the solid powder particles. The filter is provided so that the reformed gas and the solid powder can be separated. The gas-solid separation device 36 may be provided so as to be able to separate the reformed gas and the solid powder other than the filter. For example, by using a known centrifuge, the reformed gas and the solid powder are separated. It may be provided so as to be separable.

  Thus, the gas-solid separation device 36 provided so as to be able to separate the reformed gas and the solid powder has a reformed gas supply passage 40 that is a recirculation passage through which the reformed gas can flow into the intake passage 10 of the cylinder 5. Is connected. The reformed gas supply passage 40 is connected to the intake passage 10 at an end located on the opposite side of the end connected to the gas-solid separator 36, and the reformed gas is supplied to the gas-solid separator 36. It is formed so that it can flow into the intake passage 10. The reformed gas supply passage 40 has a reformed gas flow rate adjustment valve 41 that can open and close the reformed gas supply passage 40 in the vicinity of the portion of the reformed gas supply passage 40 connected to the intake passage 10. It is arranged.

  An injector 11 provided in the intake passage 10 and a reforming fuel injector 25 provided in the mixing portion 31 of the reforming reaction layer 30 are provided in a vehicle including the internal combustion engine 1 and are used for operating the internal combustion engine 1. It is connected to a fuel tank 45 that stores the fuel. The fuel tank 45 includes a feed pump 46 that can send the fuel in the fuel tank 45 to the outside. The fuel in the fuel tank 45 is supplied to the injector 11 and the reforming fuel injector 25 by the feed pump 46. It is provided as possible.

  The injector 11, the reforming fuel injector 25, the throttle valve 12, the reformed gas flow rate adjusting valve 41, the air flow meter 13, and the CaO tank 35 are mounted on the vehicle and control an ECU (Electronic Control Unit). ) 50.

  The exhaust gas reforming apparatus 3 according to the first embodiment is configured as described above, and the operation thereof will be described below. In the internal combustion engine 1 including the exhaust gas reforming apparatus 3 according to the first embodiment, when the vehicle on which the internal combustion engine 1 is mounted is operated, the ECU 50 controls the throttle valve according to the opening degree of an accelerator pedal (not shown) provided in the vehicle interior. 12 is controlled. As a result, air corresponding to the opening of the throttle valve 12 flows through the intake passage 10. When air flows into the intake passage 10, the flow rate of the air is detected by the air flow meter 13, and the detection result by the air flow meter 13 is acquired by the ECU 50.

  The ECU 50 that has acquired the detection result by the air flow meter 13 makes a comprehensive judgment together with information related to the driving state such as the opening degree of the accelerator pedal, controls the injector 11, and operates the injector 11. During operation of the internal combustion engine 1, the fuel in the fuel tank 45 is supplied to the injector 11 and the reforming fuel injector 25 by the feed pump 46 provided in the fuel tank 45, so that the ECU 50 operates the injector 11, The injector 11 injects an amount of fuel into the intake passage 10 according to control by the ECU 50.

  Thus, by injecting fuel from the injector 11 into the intake passage 10, the injected fuel is mixed with air flowing through the intake passage 10 and flows into the intake passage 10 as an air-fuel mixture. The air-fuel mixture flowing in the intake passage 10 branches along the intake passage 10 formed by branching, and is sucked into the four cylinders 5 of the internal combustion engine 1. In the air-fuel mixture sucked into the cylinders 5, the fuel in the air-fuel mixture burns in the combustion stroke of each cylinder 5, and the exhaust gas after combustion flows out from the cylinder 5 into the exhaust passage 20 in the exhaust stroke. When exhaust gas flows into the exhaust passage 20, most of the exhaust gas passes through the main exhaust passage 21 of the exhaust passage 20 and is released to the atmosphere.

  Of the exhaust gas flowing into the exhaust passage 20, a part of the exhaust gas flows into the reforming passage 22, and the reforming passage 22 is provided with a CaO tank 35. Further, the CaO tank 35 is formed so that the CaO stored therein can be supplied to the exhaust gas flowing through the reforming passage 22 by the ECU 50 at an arbitrary supply amount. The tank 35 supplies CaO with an arbitrary supply amount to the exhaust gas.

When the CaO tank 35 is controlled by the ECU 50 and the CaO stored in the CaO tank 35 is supplied to the exhaust gas flowing through the reforming passage 22, the exhaust gas and CaO are mixed. Here, the main components of the exhaust gas when gasoline is used as the fuel for operating the internal combustion engine 1 are CO ₂ (carbon dioxide), H ₂ O (water), and N ₂ (nitrogen). When CaO is supplied to the exhaust gas composed of such components and the exhaust gas and CaO are mixed, CaO reacts exothermically with H ₂ O contained in the exhaust gas. Specifically, CaO and H ₂ O undergo an exothermic reaction to generate Ca (OH) ₂ (calcium hydroxide) as shown in the following chemical reaction formula (1). At that time, the exhaust gas generates heat around 100 ° C. due to an exothermic reaction between CaO and H ₂ O.
CaO + H ₂ O → Ca (OH) ₂ (1)

As described above, when CaO is supplied from the CaO tank 35 to the exhaust gas flowing through the reforming passage 22, an exothermic reaction occurs when CaO and the exhaust gas are mixed, but the exhaust gas mixed with the CaO. Is a further exothermic reaction based on the heat of reaction when CaO and H ₂ O undergo an exothermic reaction. Specifically, as shown in the following chemical reaction formula (2), Ca (OH) ₂ generated by the exothermic reaction between CaO and H ₂ O and the CO ₂ contained in the exhaust gas undergo an exothermic reaction. , CaCO ₃ (calcium carbonate) and H ₂ O. At that time, the exhaust gas generates heat at 700 to 800 ° C. due to an exothermic reaction between Ca (OH) ₂ and CO ₂ .
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O (2)

  Thus, the exhaust gas whose temperature has been increased by mixing with CaO flows into the reforming reaction layer 30. The reforming reaction layer 30 has a mixing unit 31 and a reforming reaction unit 32. When exhaust gas that has become hot due to an exothermic reaction with CaO flows into the reforming reaction unit 32, The reforming reaction section 32 is heated by the heat of the exhaust gas, and the temperature rises.

  Further, the reforming fuel injector 25 is provided in the mixing portion 31 of the reforming reaction layer 30. The reforming fuel injector 25 is controlled by the ECU 50 and is operably provided. Further, since the fuel in the fuel tank 45 is supplied to the reforming fuel injector 25 as in the case of the injector 11, the reforming fuel injector 25 is operated by the ECU 50 by operating the reforming fuel injector 25. An amount of fuel corresponding to control by the ECU 50 is injected into the mixing unit 31 as reforming fuel.

Thus, by injecting the reforming fuel from the reforming fuel injector 25 into the mixing unit 31, the injected reforming fuel is mixed with the exhaust gas flowing through the mixing unit 31, and the exhaust gas It flows to the reforming reaction section 32 located on the downstream side of the mixing section 31 in the flow direction. In this way, when the exhaust gas and the reforming fuel are mixed and flow into the reforming reaction section 32, the reforming reaction section 32 is heated to a high temperature by the heat of the exhaust gas that has become a high temperature. Therefore, the exhaust gas and the reforming fuel are subjected to an endothermic reaction by the reforming catalyst. Specifically, when the chemical formula of the main component of gasoline, which is a reforming fuel, is aCnHm, this aCnHm and the CO ₂ and H ₂ O contained in the exhaust gas undergo an endothermic reaction, and the following chemical reaction formula As shown in (3), bH ₂ and cCO (carbon monoxide) are generated. That is, the reforming reaction unit 32 generates a reformed gas by causing an endothermic reaction between the exhaust gas and the reforming fuel.
aCnHm + CO ₂ + H ₂ O → bH ₂ + cCO (3)

Products generated by supplying CaO from the CaO tank 35 to the exhaust gas, reformed gas generated by endothermic reaction in the reforming reaction section 32, and endothermic reaction in the reforming reaction section 32 The exhaust gas that has not been discharged flows out of the reforming reaction layer 30 and flows to the gas-solid separation device 36 located on the downstream side of the reforming reaction layer 30 in the flow direction of the exhaust gas. That is, H ₂ , CO, CaCO ₃ , H ₂ O, and N ₂ mainly flow through the gas-solid separation device 36. This gas-solid separation device 36 is provided so as to be able to separate gas and solid powder. Of H ₂ , CO, CaCO ₃ , H ₂ O, and N ₂ flowing through the gas-solid separation device 36, H ₂ , CO, H ₂ O, and N ₂ flow into the gas-solid separator 36 in a gas state, and CaCO ₃ flows into the gas-solid separator 36 in a solid powder state. For this reason, CaCO ₃ is separated by the gas-solid separation device 36, and the remainder flows as reformed gas into the reformed gas supply passage 40.

  A reformed gas flow rate adjusting valve 41 is provided in the reformed gas supply passage 40 through which the reformed gas flows. The reformed gas flow rate adjusting valve 41 is provided so that the opening degree can be controlled by the ECU 50. For this reason, the ECU 50 adjusts the opening degree of the reformed gas flow rate adjusting valve 41 by controlling the reformed gas flow rate adjusting valve 41 in accordance with the driving state of the vehicle.

  Here, the reformed gas supply passage 40 in which the reformed gas flow rate adjusting valve 41 is provided is connected to the intake passage 10, but the air flowing in the intake passage 10 and the reformed flowing in the reformed gas supply passage 40. As for the gas, the pressure of the reformed gas flowing in the reformed gas supply passage 40 is higher. For this reason, in a state where the intake passage 10 and the reformed gas supply passage 40 communicate with each other, the reformed gas flowing in the reformed gas supply passage 40 flows into the intake passage 10. Therefore, when the reforming gas flow rate adjustment valve 41 is controlled by the ECU 50 and the opening degree of the reforming gas flow rate adjustment valve 41 is increased, the reformed gas flowing into the reformed gas supply passage 40 is introduced into the intake passage 10. When the opening of the reformed gas flow rate adjustment valve 41 is reduced, the amount of reformed gas flowing into the intake passage 10 decreases.

The amount of reformed gas corresponding to the degree of opening of the reformed gas flow rate adjustment valve 41 flows in the intake passage 10 as described above. These reformed gases flow in the intake passage 10 when the internal combustion engine 1 is operated. It is sucked into the cylinder 5 of the internal combustion engine 1 together with air. Thus, the reformed gas sucked into the cylinder 5 contains H ₂ that is a combustible gas. When the fuel burns in the cylinder 5 into which the reformed gas has flowed, ₂ also burns. Therefore H ₂ is a gas to the rapid combustion, when the H ₂ is burned, H ₂ in the cylinder 5 is burned at a rapid burn rate. Since H ₂ contained in the reformed gas generated by reforming the exhaust gas can be combusted in the cylinder 5 in this way, the exhaust gas is reused, and the thermal efficiency is improved.

In addition, since CaCO ₃ separated from the reformed gas by the gas-solid separator 36 is harmless, it may be discarded when a predetermined amount is accumulated, but may be used as an additive such as chalk or rubber, You may heat and reproduce | regenerate to CaO. As described above, when CaCO ₃ is heated to regenerate CaO, CO ₂ is generated. However, it is preferable to treat the CO ₂ so as not to be released into the atmosphere, for example, in the underground.

  The above exhaust gas reforming apparatus 3 is provided with a CaO tank 35 capable of mixing exhaust gas and CaO on the upstream side of the reforming reaction section 32 in the exhaust gas flow direction. For this reason, exhaust gas and CaO can be mixed on the upstream side of the reforming reaction section 32 to cause the exhaust gas and CaO to undergo an exothermic reaction. Thereby, the reforming reaction part 32 can be heated using the reaction heat at the time of the exothermic reaction between the exhaust gas and CaO, and the exhaust gas and the reforming fuel can be subjected to an endothermic reaction more reliably. Moreover, since only the CaO tank 35 for mixing the exhaust gas with CaO is provided as means for heating the reforming reaction section 32, the reforming reaction section 32 can be heated with a simple configuration. As a result, the reforming fuel and the exhaust gas can be more reliably reformed with a simple configuration.

Further, since the gas-solid separation device 36 is provided, the gas generated by mixing the CaO into the exhaust gas and the CaCO ₃ generated in the solid powder state are separated, and only the gas is reformed gas supply passage 40. Can be introduced into the intake passage 10. Thereby, it is possible to prevent impurities unnecessary for combustion in the cylinder 5 from flowing into the cylinder 5. As a result, more stable combustion can be obtained.

Further, the exothermic reaction between CaO and H ₂ O contained in the exhaust gas can react at room temperature, and Ca (OH) ₂ produced by the reaction between CaO and H ₂ O and CO ₂ contained in the exhaust gas. The exothermic reaction with OH causes an exothermic reaction due to the heat of reaction during the exothermic reaction between CaO and H ₂ O. In addition, since the reaction heat during the exothermic reaction between Ca (OH) ₂ and CO ₂ is high, the heat required for endothermic reaction of aCnHm, CO ₂ and H ₂ O in the reforming reaction section 32 is improved. The reforming reaction unit 32 can cause a reforming reaction between the reforming fuel and the exhaust gas. Therefore, when the reforming reaction portion 32 performs the reforming reaction between the reforming fuel and the exhaust gas, the reforming reaction is not affected by the temperature of the exhaust gas, that is, without being influenced by the operating state of the internal combustion engine 1. Can be performed. As a result, the reforming fuel and the exhaust gas can be more reliably reformed.

Also, _{H 2} O to make an exothermic reaction with CaO, in order to use of _{H 2} O in the exhaust gas, provided supply device for supplying of _{H 2} O for the purpose of which the exothermic reaction of CaO and _{H 2} O Without causing an exothermic reaction. As a result, reforming of the reforming fuel and the exhaust gas can be performed more reliably and with a simple configuration.

Further, as the heat source for heating the reforming reaction section 32, the reaction heat generated when Ca (OH) ₂ and CO ₂ undergo an exothermic reaction is used, so that CO ₂ in the exhaust gas can be reduced. . As a result, CO ₂ emission can be reduced.

The exhaust gas reforming apparatus 60 according to the second embodiment has substantially the same configuration as the exhaust gas reforming apparatus 3 according to the first embodiment, but the CO shift reaction layer 61 and the H ₂ are arranged downstream of the reforming reaction section 32. It is characterized in that a separator 62 is provided. Since other configurations are the same as those of the first embodiment, the description thereof is omitted and the same reference numerals are given. FIG. 2 is an overall configuration diagram of an internal combustion engine including an exhaust gas reforming apparatus according to Embodiment 2 of the present invention. The exhaust gas reformer 60 according to the second embodiment is provided in the internal combustion engine 1 in the same manner as the exhaust gas reformer 3 according to the first embodiment, and the exhaust passage 20 includes an exhaust main passage 21 and a reforming passage. Branches to 22. Among these, the reforming passage 22 is provided with a CaO tank 35, a reforming reaction layer 30, and a gas-solid separation device 36, and the reforming reaction layer 30 further includes a mixing unit 31 and a reforming reaction unit 32. have.

Further, in the exhaust gas reforming device 60 according to the second embodiment, the reforming passage 22 is connected to the downstream side of the gas-solid separation device 36, and the exhaust gas flowing in the reforming passage 22 in the flow direction. A CO shift reaction layer 61 is provided on the downstream side of the gas-solid separation device 36. The CO shift reaction layer 61 is provided so as to be able to generate a combustible gas from a gas other than the combustible gas among the reformed gases generated in the reforming reaction section 32, and is known in the art. (Omitted). That is, the CO shift reaction layer 61 is provided so that H ₂ can be generated from a gas other than the reformed gas H ₂ .

Further, on the downstream side of the CO shift reaction layer 61 in the flow direction of the exhaust gas flowing through the reforming passage 22, combustion for separating H ₂ which is a combustible gas from the reformed gas generated in the reforming reaction section 32. An H ₂ separator 62 which is a possible gas separation means is provided. The H ₂ separator 62 includes an H ₂ separation membrane (not shown) whose main component is Pd (palladium), for example, so that H ₂ can be separated from the reformed gas.

The thus H ₂ H ₂ separator 62 provided to be separated, reformed mainly H ₂ reformed gas supply passage capable of flowing and H ₂ separated by the separator 62 to the intake passage 10 of the gas 40 and a gas other than the gas flowing in the reformed gas supply passage 40 out of the reformed gas flowing in the H ₂ separator 62, that is, a reformed gas in which a gas other than H ₂ in the reformed gas flows. A side exhaust passage 65 is connected. The reformed gas supply passage 40 connected to the H ₂ separator 62 is formed so that at least H ₂ which is a combustible gas can flow into the intake passage 10 of the cylinder 5.

  Further, the reformed gas supply passage 40 is provided with a reformed gas flow rate adjustment valve 41 capable of opening and closing the inside of the reformed gas supply passage 40 in the vicinity of the portion connected to the intake passage 10 in the reformed gas supply passage 40. The reformed gas flow rate adjustment valve 41 is provided so as to be controllable by the ECU 50.

  The exhaust gas reforming apparatus 60 according to the second embodiment is configured as described above, and the operation thereof will be described below. During operation of the internal combustion engine 1 including the exhaust gas reforming device 60 according to the second embodiment, the ECU 50 controls the opening of the throttle valve 12 according to the opening of the accelerator pedal, so that the opening of the throttle valve 12 is adjusted. A large amount of air flows into the intake passage 10. The amount of intake air flowing through the intake passage 10 is detected by an air flow meter 13 provided in the intake passage 10 and transmitted to the ECU 50.

  Further, an injector 11 is provided in the intake passage 10, and the injector 11 is controlled by the ECU 50, whereby an amount of fuel corresponding to the operating state of the internal combustion engine 1 is injected from the injector 11. When fuel is injected from the injector 11, the fuel is mixed with air flowing through the intake passage 10 and is taken into each cylinder 5 of the internal combustion engine 1 in the state of the air-fuel mixture.

  The air-fuel mixture sucked into the cylinder 5 is combusted in the combustion stroke of the cylinder 5, and the gas after combustion becomes exhaust gas and flows from the inside of each cylinder 5 to the exhaust passage 20 in the exhaust stroke. The exhaust gas that has flowed into the exhaust passage 20 flows into the exhaust main passage 21 and the reforming passage 22 separately. Among these, CaO is supplied from the CaO tank 35 to the exhaust gas flowing into the reforming passage 22. As a result, the exhaust gas and CaO undergo an exothermic reaction as shown in the chemical reaction formulas (1) and (2) to generate heat. Since the reforming reaction layer 30 is provided on the downstream side of the CaO tank 35 in the flow direction of the exhaust gas flowing through the reforming passage 22, the reaction heat when the CaO and the exhaust gas undergo an exothermic reaction is When flowing through the reforming reaction section 32 of the reforming reaction layer 30, it is transmitted to the reforming reaction section 32. Thereby, the temperature of the reforming reaction part 32 rises.

  A reforming fuel injector 25 is provided in the mixing portion 31 of the reforming reaction layer 30, and the reforming fuel injector 25 is controlled by the ECU 50 according to the operating state of the internal combustion engine 1. The fuel injector 25 injects reforming fuel into the exhaust gas in the mixing unit 31.

  The exhaust gas in which the reforming fuel is injected in the mixing unit 31 flows to the reforming reaction unit 32 located on the downstream side of the mixing unit 31 in a state of being mixed with the reforming fuel. Since the temperature of the reforming reaction section 32 is increased due to the exothermic reaction between CaO and the exhaust gas, when the reforming reaction section 32 flows to the reforming reaction section 32 in a state where the exhaust gas and the reforming fuel are mixed, The reforming reaction unit 32 reforms the exhaust gas and the reforming fuel by performing an endothermic reaction shown in the chemical reaction formula (3) to generate a reformed gas.

The reformed gas generated in the reforming reaction section 32, the exhaust gas that did not undergo endothermic reaction in the reforming reaction section 32, and the product generated by supplying CaO from the CaO tank 35 to the exhaust gas are: The gas flows into the gas-solid separation device 36 located on the downstream side of the reforming reaction layer 30, and is separated into gas and solid powder by the gas-solid separation device 36. For this reason, CaCO ₃ is separated by the gas-solid separation device 36, and the remaining gas flows as a reformed gas to the CO shift reaction layer 61 located on the downstream side of the gas-solid separation device 36.

Thus, the reformed gas after separating CaCO ₃ flows through the CO shift reaction layer 61. When the reformed gas flows into the CO shift reaction layer 61, the reformed gas is cooled to about 300 ° C. In addition, since the CO shift reaction layer 61 has a catalyst for CO shift reaction, the CO shift reaction layer 61 causes the reformed gas to perform a CO shift reaction. For details, CO shift reaction layer 61, and a CO and _{H 2} O of the components of the reformed gas by CO shift reaction, as shown in the following chemical reaction equation: (4), the CO ₂ and _{H 2} Generate. That is, the CO shift reaction layer 61 generates H ₂ that is a combustible gas by performing a CO shift reaction with a gas other than H ₂ contained in the reformed gas.
CO + H ₂ O → CO ₂ + H ₂ (4)

The reformed gas in which H ₂ is generated by the CO shift reaction layer 61 further flows to the H ₂ separator 62 located on the downstream side of the CO shift reaction layer 61. If the reformed gas flows in _{H 2} separator 62, _{H 2} separator 62, a reformed gas and _{H 2,} is separated into a gas other than _{H 2.} Specifically, the reformed gas flowing in the H ₂ separator 62 is mainly composed of H ₂ , CO ₂ , and N ₂ , but the H ₂ separator 62 separates H ₂ out of these, and H ₂ and CO _2. And N ₂ . Of the separated reformed gases, CO ₂ and N ₂ flow into the reformed gas side exhaust passage 65 and are released to the atmosphere, or flow from the reformed gas side exhaust passage 65 to the exhaust main passage 21, The exhaust gas flows through the exhaust main passage 21 and merges.

Of the reformed gas separated by the H ₂ separator 62, H ₂ flows into the reformed gas supply passage 40, and the flow rate is adjusted by adjusting the opening of the reformed gas flow rate adjusting valve 41 by the ECU 50. , Flows into the intake passage 10. The H ₂ flowing into the intake passage 10 is sucked into the internal combustion engine 1 together with the air-fuel mixture flowing through the intake passage 10. When the air-fuel mixture containing H ₂ is sucked into the internal combustion engine 1, the H ₂ is combusted in the cylinder 5 of the internal combustion engine 1 together with the fuel in the air-fuel mixture, and the exhaust gas after combustion flows into the exhaust passage 20.

Or more exhaust gas reforming device 60, due to the provision of H ₂ separator 62 separates and H ₂ is combustible gas from the reformed gas produced in the reforming reaction unit 32, only the H ₂ breaks The quality gas supply passage 40 can flow into the intake passage 10. Thereby, it is possible to suppress a gas unnecessary for combustion in the cylinder 5 from flowing into the cylinder 5. As a result, more stable combustion can be obtained and combustion efficiency can be improved.

In the exhaust gas reforming apparatus 60 according to the second embodiment, the CO shift reaction layer 61 is provided on the downstream side of the gas-solid separation device 36, but the CO shift reaction layer 61 is on the upstream side of the gas-solid separation device 36. May be provided. Even when the CO shift reaction layer 61 is provided on the upstream side of the gas-solid separation device 36, the order in which the gas-solid separation device 36 separates CaCO ₃ and the order in which the CO shift reaction layer 61 generates H ₂ are simply switched. Even when these are replaced, CaCO ₃ is separated in the H ₂ separator 62, and the reformed gas after H ₂ is generated in the CO shift reaction layer 61 flows. This prevents the damage of H ₂ separator 62 by CaCO ₃ produced in the form of a solid powder, and, for the more H ₂ can be supplied to the internal combustion engine 1, more stable combustion Can be obtained more reliably.

  Moreover, although the internal combustion engine 1 provided with the exhaust gas reforming apparatuses 3 and 60 described above is an internal combustion engine 1 that uses gasoline as fuel, the fuel of the internal combustion engine 1 may be other than gasoline, such as light oil or Alcohol may be used. Even when the fuel of the internal combustion engine 1 is other than gasoline, there is provided a heating element mixing means capable of mixing a heating element that reacts exothermically with the exhaust gas when mixed with the exhaust gas, so that the heating element is modified in the flow direction of the exhaust gas. The reforming reaction section 32 can be heated by reaction heat by mixing with the exhaust gas upstream of the quality reaction section 32. Thus, the endothermic reaction between the exhaust gas and the reforming fuel can be more reliably performed with a simple configuration. As a result, the reforming fuel and the exhaust gas can be more reliably reformed with a simple configuration.

  As described above, the exhaust gas reforming apparatus according to the present invention is useful for an exhaust gas reforming apparatus that sucks the reformed gas into the internal combustion engine together with the exhaust gas, and particularly when the reformed gas is generated by an endothermic reaction. Suitable for

1 is an overall configuration diagram of an internal combustion engine including an exhaust gas reforming apparatus according to Embodiment 1 of the present invention. It is a whole block diagram of an internal combustion engine provided with the exhaust-gas reforming apparatus which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3, 60 Exhaust gas reformer 5 Cylinder 10 Intake passage 11 Injector 12 Throttle valve 13 Air flow meter 14 Air cleaner 20 Exhaust passage 21 Exhaust main passage 22 Reforming passage 25 Reforming fuel injector 30 Reforming reaction layer 31 Mixing unit 32 Reforming reaction unit 35 CaO tank 36 Gas-solid separation device 40 Reforming gas supply passage 41 Reforming gas flow rate adjusting valve 45 Fuel tank 46 Feed pump 50 ECU
61 CO shift reaction layer 62 H ₂ separator 65 Reformed gas side exhaust passage

Claims (3)

Reforming means for generating a reformed gas containing combustible gas combustible in the cylinder by causing an endothermic reaction between the exhaust gas discharged from the cylinder of the internal combustion engine and the reforming fuel;
A recirculation passage capable of flowing at least the combustible gas into the intake passage of the cylinder;
A heating element mixing means capable of mixing a heating element that undergoes an exothermic reaction when mixed with the exhaust gas into the exhaust gas upstream of the reforming means in the flow direction of the exhaust gas;
An exhaust gas reforming apparatus comprising:   The exhaust gas reforming apparatus according to claim 1, further comprising gas-solid separation means for separating a gas and a solid produced when the exhaust gas and the heating element are mixed.   The reforming means further comprises combustible gas separation means for separating the combustible gas from the reformed gas generated by endothermic reaction of the exhaust gas and the reforming fuel. The exhaust gas reforming apparatus according to claim 1 or 2.

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