JP4052847B2 - Gas engine with fuel reformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a gas engine equipped with a fuel reformer that reforms natural gas into reformed fuel.
[0002]
[Prior art]
  Improvement of engine thermal efficiency is indispensable for solving major global problems such as global warming and depletion of energy resources. Since these problems could not be solved by extending the conventional technology, reforming the fuel was considered as a new method. In order to improve the thermal efficiency, it is only necessary to increase the power of the effective work generated from the engine. However, the thermal efficiency of a diesel engine with a large compression ratio, which is currently considered to be the best, is approximately 40 to 48%, and more Improvement is not possible. However, since most of the heat is dissipated in the exhaust gas and cooling water, a means to recover these heats has been considered, but it has been possible to improve the thermal efficiency by several percent, but it was impossible.
[0003]
  Conventionally, a gas engine using natural gas as a main fuel has been developed as a cogeneration system. The cogeneration system extracts electric energy from a generator driven by engine power, heats the exhaust gas energy to heat water with a heat exchanger, and uses the hot water for hot water supply. Conventionally, as an engine using natural gas as a fuel, for example, there are those disclosed in JP-A-6-108865 and JP-A-6-101495.
[0004]
  The cogeneration type gas engine disclosed in Japanese Patent Application Laid-Open No. 6-108865 uses an exhaust gas to reduce the exhaust gas temperature through a turbocharger, an energy recovery device and a steam generator, and uses a low temperature exhaust gas for EGR._XThe turbocharger is driven by the exhaust gas from the heat-insulated gas engine, and the energy recovery device equipped with the generator is driven by the exhaust gas from the turbocharger. The cogeneration type gas engine sends exhaust gas from an energy recovery device to a steam generator of a heat exchanger, converts water into steam by the steam generator, and drives the steam turbine with the steam to recover it as electric energy. To do.
[0005]
  Further, as a gas engine using a fuel obtained by reforming natural gas, for example, one disclosed in Japanese Patent Application Laid-Open No. 11-93777 is known. The natural gas reforming apparatus disclosed in the publication is a natural gas main component CH._FourCO and H₂Pyrolysis to reformed fuels of CO2 to improve thermal efficiency and CO in exhaust gas₂In the exhaust gas discharged using pyrolysis for pyrolysis₂Reduce content, NO_XIt suppresses generation | occurrence | production of this. In the natural gas reformer, an exhaust gas passage body that forms an exhaust gas passage is disposed in an exhaust gas pipe, a gas fuel case through which gas fuel flows is disposed outside the exhaust gas pipe, and the gas fuel passage is disposed in the gas fuel case. A porous member made of porous ceramics to be formed is arranged, and CH is formed on the surface of the porous member._FourAnd CO₂CO and H₂A catalyst having the effect of converting to a reformed fuel is coated, and a heat insulating material is arranged on the outer periphery of the gas fuel pipe.
[0006]
  Further, there is a heat exchange device disclosed in Japanese Patent Application Laid-Open No. 11-6601. The heat exchanger comprises a first stage heat exchanger and a second stage heat exchanger provided in an exhaust passage for heating steam with exhaust gas from the engine. The first stage heat exchanger is composed of a steam passage through which steam flows disposed in the first casing and an exhaust gas passage through which exhaust gas disposed in the steam passage flows. The second stage heat exchanger includes a water / steam passage capable of storing water disposed in a second casing provided below the first casing, and an exhaust gas through which exhaust gas disposed around the water / steam passage flows. It consists of a gas passage. A porous ceramic member is disposed in each passage.
[0007]
  Japanese Patent Application Laid-Open No. 11-93777 discloses a heat exchanger applied to a natural gas reformer. The natural gas reformer is composed of CH, the main component of natural gas._FourCO and H₂It is thermally decomposed into a reformed fuel, which improves the thermal efficiency and reduces the CO in the exhaust gas.₂In the exhaust gas discharged using pyrolysis for pyrolysis₂The content is reduced. In the natural gas reformer, an exhaust gas passage body that forms an exhaust gas passage is disposed in an exhaust gas pipe, a gas fuel case through which gas fuel flows is disposed outside the exhaust gas pipe, and the gas fuel passage is disposed in the gas fuel case. A porous member made of porous ceramics to be formed is arranged, and CH is formed on the surface of the porous member._FourAnd CO₂CO and H₂A catalyst having the effect of converting to a reformed fuel is coated, and a heat insulating material is arranged on the outer periphery of the gas fuel pipe.
[0008]
[Problems to be solved by the invention]
  However, in order to use natural gas as engine fuel, the technical idea of reforming natural gas using the thermal energy of exhaust gas has been researched and developed by the present inventors. In the test, it was found that ignition was extremely difficult in the case of natural gas, and problems such as startability were extremely difficult. When natural gas is reformed and the reformed gas is used as fuel, the reformed fuel is CO and H.₂In some cases, however, the calorific value increases by about 30%, but reforming does not proceed completely, and the properties are not always stable. In a gas engine using natural gas as a fuel, if the combustion chamber is made of a material such as ceramics with a heat shield structure, the compression temperature of the air rises above the self-ignition temperature of natural gas, eliminating the need for an ignition device. However, knocking occurs. So, very dilute and O₂In addition to the main combustion chamber that introduces EGR and air to reduce the concentration, a secondary combustion chamber that introduces fuel to create a rich air-fuel mixture is provided, and a communication port that connects the main combustion chamber and the auxiliary combustion chamber. A control valve is provided, and a high-efficiency cogeneration engine can be provided by operation with a diesel cycle. According to such a structure, the exhaust gas of the gas engine becomes a high temperature of 850 ° C. or higher when the combustion chamber is configured as a heat shield structure. By recovering thermal energy from the high-temperature exhaust gas, it is possible to improve the total thermal efficiency of the engine.
[0009]
  By the way, the main component of natural gas is methane CH._FourBecause it has a large calorific value and exists in nature, it is expected to be a future alternative fuel for oil. CH_FourCO₂When pyrolyzed through a catalyst in the presence of_FourIs CO and H₂Is converted into CO and H₂The total calorific value is CH_FourThe amount of heat is more than 1.3 times, that is, 1.3 times. Therefore, the thermal energy of the high-temperature exhaust gas from the heat shield gas engine is_FourBy reforming natural gas into reformed fuel by using it for thermal decomposition of the fuel, the heat generation of the reformed fuel is increased, the thermal efficiency of the engine is improved, and resources are saved.₂Can be suppressed.
[0010]
  However, CH in natural gas_FourCO₂Due to the heat energy of the exhaust gas due to the presence of₂Separated from exhaust gas in a natural gas reformer that reforms to CO and CO₂CO when using₂O in the separation gas containing₂Is contained in the catalytic device of the natural gas reformer.₂And H₂There is a risk that CO and CO may react, and in some cases, cause a reaction explosion. Therefore, the CO separated from the exhaust gas fed to the natural gas reformer₂O contained in the separation gas containing₂Must be reduced as much as possible.
[0011]
  In general, exhaust gas discharged from a diesel engine is N₂Is 75%, CO₂15% and O₂Is about 10%, but this is not always the case.₂May be included. Also, the exhaust gas is CO₂Separator CO₂CO separated from exhaust gas by passing through a separation membrane₂The separation gas containing CO is CO₂90%, N₂8% and O₂The separation gas of such a component is normally sent to a natural gas reformer, but it does not matter so much, but CO with a high exhaust gas concentration.₂Separation membrane abnormalities easily occur, O₂May occur in an amount of 5% or more. Therefore, more than 5% O₂When the separated gas containing is fed into the natural gas reformer, the H produced by the natural gas reformer₂And CO are O in the separated gas.₂Reaction explosion occurs and a very dangerous situation occurs. Even if the reformed fuel generated with difficulty as described above is supplied to the engine, the performance of the engine cannot be improved unless the reformed fuel is completely burned.
[0012]
[Means for Solving the Problems]
  An object of the present invention is to solve the above-described problem, and a natural gas that can be effectively burned in an engine using a reformed fuel obtained by reforming natural gas and the performance thereof can be improved. A gas engine that supplies fuel to the engine as a fuel is provided with a secondary combustion chamber in the upper part of the cylinder of the main combustion chamber, a fuel reformer that reforms natural gas near the outlet of the exhaust pipe, and a reformation in the secondary combustion chamber The object is to provide a gas engine equipped with a fuel reformer that supplies pre-natural gas and performs premixed compression diesel combustion that supplies reformed fuel and air to the intake pipe.
[0013]
  The present invention relates to a cylinder head attached to a cylinder block, a piston reciprocating in a cylinder formed on the cylinder block side, a main combustion chamber formed on the piston side, and a sub-combustion chamber provided on the cylinder head , A sub-chamber control valve disposed at a communication port communicating the main combustion chamber and the sub-combustion chamber, heat energy of exhaust gas discharged from the main combustion chamber, and CO₂ And H ₂ ONatural gas using H₂A fuel reformer for reforming to CO and CO, a reformed fuel valve provided in a reformed fuel passage disposed in an intake pipe, and a natural gas supply passage for supplying natural gas to the auxiliary combustion chamber Natural gas valve
  In order to burn the natural gas in the auxiliary combustion chamber,The sub chamber control valve is opened in the latter half of the compression stroke, and a lean mixture of air and reformed fuel is blown from the main combustion chamber into the sub combustion chamber to ignite and burn the natural gas in the sub combustion chamber., The reformed fuel present in the main combustion chamber is burned by the combustion flame ejected from the sub-combustion chamber.Relates to a gas engine.
[0014]
  In this gas engine, a glow plug is disposed on the upper portion of the auxiliary combustion chamber facing the auxiliary chamber control valve.
[0015]
  Further, in this gas engine, the fuel reformer includes a cylindrical rotary container that is rotatably supported by a cylindrical housing and is internally divided into a plurality of compartments in a rotation direction by a partition plate, and A fuel reforming control valve for sequentially supplying the exhaust gas from the exhaust pipe, water vapor from the water vapor pipe, and the natural gas from the natural gas pipe to the rotary container; A porous metal body carrying an adsorbent and a catalyst is accommodated, and an exhaust pipe, a water vapor pipe and a natural gas pipe are connected to the inlet side opening and the outlet side opening of the housing,Said natural gas valveBeforeIn order to supply the natural gas to the auxiliary combustion chamber, it is opened from the latter half of the intake stroke to the first half of the compression stroke when the sub chamber control valve is closed.The reformed fuel valve is opened in the intake stroke to supply the reformed fuel to the main combustion chamber, and the sub chamber control valve is opened in the latter half of the compression stroke and closed in the latter half of the exhaust stroke. Is set.0016]
  The portions of the sub-combustion chamber and the sub-chamber control valve that are in contact with the combustion gas are coated with a ceramic such as corrosion-resistant zirconia.
0017]
  The fuel reformer includes a heat exchanger that recovers thermal energy of the exhaust gas, and a CO in the exhaust gas.₂And a catalyst device for reforming the natural gas into the reformed fuel.
0018]
  The gas engine equipped with this fuel reformer is configured as described above, and the properties of the reformed fuel are not necessarily determined, so that the ignition temperature changes and the air-fuel mixture in the main combustion chamber does not self-ignite. Therefore, a control valve is placed at the communication port that connects the main combustion chamber and the auxiliary combustion chamber, and the auxiliary combustion chamber is filled with natural gas fuel. When fuel is supplied and the control valve is opened in the latter half of the compression stroke and high-temperature compressed gas is sent to the auxiliary combustion chamber, the rich mixture comes into contact with the glow plug at the back of the auxiliary combustion chamber and ignites, creating a combustion nucleus. Ignition progresses steadily. Combustion in the sub-combustion chamber is configured so that ignition is generated by the heat source of the glow plug, so that heat is not transferred to the wall in contact with the combustion gas of the sub-combustion chamber and the sub-chamber control valve. Ceramics such as zirconia are coated. At this time, if reformed fuel and air with unstable combustion are supplied to the main combustion chamber, and natural gas with fixed properties such as ignition is supplied to the auxiliary combustion chamber, the ignition conditions in the auxiliary combustion chamber Therefore, the opening of the control valve can be made constant and combustion can be steadily performed in the auxiliary combustion chamber. Further, since the amount of fuel supplied to the auxiliary combustion chamber can be changed by changing the gas pressure or the gas pumping time, the amount of fuel supplied to the auxiliary combustion chamber can be changed successively.
0019]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of a gas engine equipped with a fuel reformer according to the present invention will be described below with reference to the drawings. The gas engine equipped with the fuel reformer according to the present invention uses natural gas as fuel, and natural gas, that is, CH as its main component._FourCO2 contained in the exhaust gas while utilizing the thermal energy of the engine exhaust gas₂Using CO and H₂The fuel is reformed to increase the amount of heat of the fuel and the thermal efficiency of the engine is increased, which is preferable when applied to engines such as cogeneration systems, automobiles and ships.
0020]
  This gas engine has a combustion chamber having a heat shielding structure and is driven by a diesel cycle using natural gas as fuel, and is mainly a main combustion chamber provided on the side of a piston 5 that reciprocates in a cylinder 4. There is a sub-combustion chamber or sub-chamber 2 provided in the main chamber 1 and the cylinder head 12, and a sub-chamber control valve 8 is provided in the communication port 27 that communicates the main chamber 1 and the sub-chamber 2. CO and H modified natural gas through the intake pipe 33 and the intake manifold 16 for supplying₂The reformed fuel and air are supplied, natural gas is directly supplied to the sub chamber 2, the sub chamber control valve 8 is opened at the end of the compression stroke, and air and An air-fuel mixture with reformed fuel is injected, and natural gas supplied to the sub chamber 2 is ignited and burned with the help of the glow plug 18. This gas engine is provided with a fuel reformer 15 consisting of a heat exchanger that absorbs the heat energy of the exhaust pipe 30 immediately after the exhaust pipe 30. CO₂For adsorbing zeolite (zeolite) and / or activated carbon, etc. and Pt, Ru, Ni, Pd, Al for modifying natural gas₂O_ThreeEtc., and a catalyst device made up of, etc. is provided.
0021]
  In this gas engine, as shown in FIG. 1, a cylinder head 12 is fixed to a cylinder block 11 via an intermediate head 13, and a sub-chamber 2 having a heat shielding structure is formed in a hole formed in the cylinder head 12. A chamber structure 21 is arranged. In the hole 50 formed in the intermediate head 13 fixed to the cylinder head 12, that is, in the cavity of the cylinder head 12, a combustion chamber member 14 that forms the main chamber 1 having a heat shield structure is disposed. This gas engine is configured such that a cylinder liner 34 is fitted into a hole formed in the cylinder block 11, and the piston 5 reciprocates in the cylinder 4 formed in the cylinder liner 34. A communication port 27 for communicating the main chamber 1 and the sub chamber 2 is formed in the sub chamber structure 21.
0022]
  Further, as shown in FIG. 2, a sub chamber control valve 8 is disposed at the communication port 27 formed in the combustion chamber member 14 in order to open and close the communication port 27. In the sub chamber structure 21, the sub chamber control valve 8 is disposed through the sub chamber 2, a seal ring 24 is disposed on the stem of the sub chamber control valve 8, and the sub chamber 2 is sealed. The sub chamber control valve 8 is configured to be opened by a valve mechanism 20 and closed by a return spring 23, for example. A natural gas supply port 28 connected to the natural gas passage 22 is formed in the upper portion of the sub chamber 2, and a natural gas valve 3 that is driven to open and close by a cam is disposed in the natural gas supply port 28. Therefore, the natural gas supply port 28 is configured to be opened and closed by the natural gas valve 3. Further, a glow plug 18 is disposed on the upper side of the sub chamber 2 opposite to the communication port 27. The glow plug 18 functions to assist the ignition and combustion of natural gas, and is provided in the upper portion, that is, the back portion of the sub chamber 2, so that the natural gas supplied into the sub chamber 2 remains from the sub chamber 2 by ignition and combustion. It is surely ejected to the main room 1 without doing.
0023]
  In this gas engine, an intake port 9 and an exhaust port 10 are formed in a cylinder head 12. The combustion chamber member 14 includes a liner upper portion 35 and a head lower surface portion 36 that constitute a part of the cylinder 4. Ports corresponding to the intake port 9 and the exhaust port 10 formed in the cylinder head 12 are formed in the head lower surface portion 36. Although not shown, an exhaust valve and an intake valve are arranged in the ports. A gasket is interposed between the cavity of the cylinder head 12 and the outer surface of the combustion chamber member 14, a heat insulating air layer 31 is formed, and the main chamber 1 is configured with a heat insulating structure. Further, a heat insulating air layer 32 is formed between the wall surface of the cavity of the cylinder head 12 and the outer surface of the sub chamber structure 21, and the sub chamber 2 has a heat insulating structure. The piston 5 includes a piston head 6 made of ceramics such as silicon nitride having excellent heat resistance, and a piston skirt 37 fixed to the piston head 6 with a coupling ring. The piston head 6 is formed with a main chamber 1 composed of a concave cavity 7. A heat insulating air layer 38 is formed between the piston head 6 and the piston skirt 37, and the main chamber 1 is configured to have a heat insulating structure.
0024]
  The sub chamber structure 21 is fitted into the cavity of the cylinder head 12, specifically, the hole 50 of the intermediate head 13 which is a part of the cylinder head, with a gasket 62 interposed as necessary. . A lower portion of the sub chamber structure 21 is fitted into a hole 39 formed in the combustion chamber member 14, and a communication port 27 formed in the sub chamber structure 21 communicates the main chamber 1 and the sub chamber 2. . Therefore, the combustion chamber structure is composed of the sub chamber structure 21 constituting the sub chamber 2 and the combustion chamber member 14 constituting the main chamber 1, and the sub chamber structure 21 is formed at the center of the combustion chamber member 14. A communication port 27 formed in the sub chamber structure 21 is formed at the center of the combustion chamber member 14 so as to communicate with the main chamber 1 and the sub chamber 2. Therefore, the sub chamber 2 formed in the sub chamber structure 21 is arranged at the substantially center of the cylinder axis. Further, a gas fuel passage 22 is formed in the cylinder head 12 and communicates with a natural gas supply port 28 formed in the sub chamber structure 21.
0025]
  Natural gas fuel as a fuel is stored in a fuel supply source such as a tank provided at an appropriate location. The natural gas fuel of the gas fuel supply source is, for example, 5 to 7 kg / cm depending on the operation of the oil feed fuel pump.²The pressurized natural gas fuel is fed into the gas fuel passage 22 through the fuel supply passage. The natural gas fuel in the gas fuel passage 22 is supplied to the sub chamber 2 when the natural gas valve opens the natural gas supply port 28.
0026]
  In this gas engine, the piston head 6 that forms the main chamber 1, the sub chamber structure 21 that forms the sub chamber 2, and the cylinder liner 34 are made of ceramics such as silicon nitride, silicon carbide, and sialon, which have excellent heat resistance. Have been made. Further, since the piston head 6 and the sub chamber structure 21 become high temperature, the sub chamber control valve 8 disposed in the communication port 27 is made of ceramics such as heat resistant metal having high temperature strength and excellent heat resistance, silicon nitride, silicon carbide and the like. It has been produced.
0027]
  In this gas engine, the fuel reformer 15 is arranged, for example, in the exhaust pipe 30 in the immediate vicinity of the exhaust port 9 so that the thermal energy of the exhaust gas can be used. A reformed fuel passage 40 is connected to the intake manifold 16 communicating with the intake port 10, and the reformed fuel supply port 29 where the reformed fuel passage 40 opens into the intake manifold 16 is provided with a reformed fuel valve 17 including an electromagnetic valve. It is arranged. The reformed fuel valve 17 is opened / closed by a command from the controller 25, and is configured to open / close in synchronization with the actuator 26 of the intake valve. Accordingly, the reformed fuel whose natural gas has been reformed by the fuel reformer 15 is brought together with air into the main chamber 1 through the intake manifold 16 by opening the reformed fuel valve 17 from the fuel reformer 15 through the reformed fuel passage 40. It is configured to be supplied. That is, the natural gas accommodated in the fuel supply source is sent to the fuel reformer 15 disposed in the exhaust pipe 30 and receives the heat energy of the exhaust gas to generate H₂And reformed fuel of CO and supplied to the main chamber 1 through the fuel supply passage by the fuel pump.
0028]
  This gas engine is configured as described above, and operates as follows. As shown in FIG. 4, this gas engine is operated by sequentially repeating four strokes of an exhaust stroke, an intake stroke, a compression stroke, and an expansion stroke. In this gas engine, the reformed fuel valve 17 opens the reformed fuel supply port 29 that opens to the intake pipe 33 and the intake manifold 16 from the initial stage to the latter half of the intake stroke when the intake valve opens the intake port 6 to the main chamber 1. Then, the reformed fuel is supplied from the reformed fuel device 15 to the main chamber 1 together with the intake air into the intake manifold 16. On the other hand, the natural gas valve 3 opens the natural gas supply port 28 through the natural gas passage 22 and the natural gas is supplied to the sub chamber 2 from the latter half of the intake stroke to the first half of the compression stroke in which the intake valve closes the intake port 6. The The ratio of the fuel supplied to the main chamber 1 and the sub chamber 2 is, for example, that the supply amount of the natural gas supplied to the sub chamber 2 is about 5 to 20% of the total amount of the fuel flow rate. The amount of reformed fuel to be supplied is about 95 to 80% of the total amount of fuel flow, and is a lean mixture that does not self-ignite in the main chamber 1.
0029]
  In this gas engine, at the end of the compression stroke, the sub-chamber control valve 8 opens the communication port 27, and the mixture of reformed fuel and air that has been compressed to a high pressure flows from the main chamber 1 to the sub-chamber 2. As shown in the pressure diagram shown in FIG. 4, the natural gas in the sub chamber 2 becomes high pressure and high temperature and is ignited and combusted in the sub chamber 2 with the help of the glow plug 18. Ascending, the combustion flame from the sub chamber 2 to the main chamber 1 passes through the communication port 27 and becomes a flame without any remaining natural gas in the sub chamber 2, and then the entire amount is blown out. Combustion propagates to the air-fuel mixture, completes secondary combustion in a short period of time, increases thermal efficiency, shifts to the expansion stroke, and pushes down the piston 5 to work. In the sub chamber control valve 8, the exhaust valve opens the exhaust port 10 to shift to the exhaust stroke, and closes the communication port 27 in the latter half of the exhaust stroke. Next, the exhaust valve closes the exhaust port 10 and the intake valve opens the intake port 9 to shift to the intake stroke. The engine is driven by repeating these strokes.
0030]
  Next, an example of the fuel reformer 15 will be described with reference to FIGS. The fuel reformer 15 is mainly provided with a control valve device that sequentially pumps exhaust gas, steam, natural gas, and air, that is, an exhaust gas valve 66, a steam valve 67, a natural gas fuel valve 68, and an air valve 65. ing. The fuel reformer 15 is a cylindrical housing 41 having a plurality of inlet-side openings 52 formed at one end surface and a plurality of outlet-side openings 53 formed at the other end surface. Has a cylindrical rotating container 42 divided into a plurality of compartments 55 in the rotation direction. The fuel reformer 15 includes an exhaust pipe 30, a water vapor pipe 45, a natural gas pipe 46 for introducing natural gas, and an air introduction pipe 64 in a sealed state at the inlet side opening 52 of the housing 41 via a seal member 59. The exhaust pipe 30, the steam pipe 45, the reformed fuel pipe 40 for sending the reformed gas, and the air introduction pipe 64 are connected to the outlet opening 53 of the housing 41 through a seal member 59. Has been. Further, the air introduction pipe 64 on the outlet side and the reformed fuel pipe 40 are connected and communicated with the intake pipe 33. The natural gas pipe 46 and the reformed fuel passage 40 are positioned corresponding to the longitudinal direction. In particular, the metal porous bodies 43 are accommodated in the compartments 55 of the rotating container 42, respectively, and have a function of modifying natural gas.
0031]
  The rotating container 42 is fixed to a rotating shaft 54 that is rotatably attached to the housing 41 via a bearing 56. An inlet 47 formed on one end surface of the rotary container 42 is positioned so as to be aligned with the inlet side opening 52 of the housing 41. The outlet 48 formed on the other end surface of the rotating container 42 is positioned so as to be aligned with the outlet side opening 53 of the housing 41. The fuel pipe includes a natural gas pipe 46 that introduces natural gas connected to the inlet side opening 52 of the housing 41 and a reformed fuel passage 40 that sends out the reformed fuel connected to the outlet side opening 53 of the housing 41. The natural gas pipe 46 and the reformed fuel passage 40 are positioned corresponding to the longitudinal direction of the rotary container 42. The rotary container 42 is rotatably supported on a base 57 via a bearing 56 in a vacuum layer 58 formed in the housing 41. The rotating container 42 is rotationally driven by a motor 51 whose rotational speed is controlled by a command from the controller 25.
0032]
  The metal porous body 43 is made of a metal material such as Ni, Cr, or Fe. The surface of the metal porous body 43 is coated with alumina, and the surface of the alumina is coated with CO in the exhaust gas.₂It is coated with zeolite powder that traps. Furthermore, natural gas is added to the surface of the zeolite powder.₂And Pt, Ru, Ni, Pd (palladium), Al as catalysts for thermal decomposition into reformed fuel of CO and CO₂O_ThreeEtc. are arranged.
0033]
  A motor 51 capable of variably controlling the rotation, stop, intermittent rotation, and rotation speed of the rotating container 42 is attached to the rotating container 42 in accordance with a command from the controller 25. In the fuel reformer 15, exhaust gas is introduced into the compartment 55 of the rotating vessel 42 through the exhaust pipe 30, and CO in the exhaust gas is introduced.₂Is adsorbed by the zeolite on the surface of the metal porous body 43, and then, by introducing water vapor vaporized by the heat energy of the exhaust gas into the compartment 55 through the steam pipe 45, the exhaust gas containing oxygen is discharged from the compartment 55. Next, the natural gas introduced into the compartment 55 through the natural gas pipe 46 is adsorbed by zeolite and / or activated carbon.₂In the presence of water vapor, natural gas is converted to CO and H₂And reforming.
0034]
  The rotating container 42 is formed in a cylindrical body such as a cylindrical shape. The rotating container 42 is partitioned into a plurality of compartments 55 that form a plurality of spaces 61 by a plurality of partition plates 49 extending in the radial direction, and the metal porous body 43 made of a refractory metal is arranged or filled in the spaces 61. ing. In the reformed fuel device 15, when the rotating container 42 rotates in the housing 41, the inlet 47 and the outlet 48 formed in the rotating container 42 include an exhaust pipe 30, a steam pipe 45, a natural gas pipe 46, and an air introduction pipe. 64 sequentially passes through the inlet-side opening 52 and the outlet-side opening 53 of the housing 41 connected thereto. The controller 25 outputs an operation command to the motor 51 to control the rotation operation of the rotating container 42 in order to bring the rotating container 42 into an optimum operating state for reforming the natural gas. Speed rotation, stop, continuous rotation, or intermittent rotation can be controlled.
0035]
  Since the fuel reformer 15 applied to this gas engine is configured as described above, exhaust gas is introduced into the compartment 55 of the rotating vessel 42 through the exhaust pipe 30 and the CO in the exhaust gas.₂Is adsorbed by the zeolite and / or activated carbon on the surface of the porous metal body 43, and then vaporized by the heat energy of the exhaust gas is sent into the compartment 55, and the O remaining in the compartment 55₂Is removed with steam, where natural gas is fed into the compartment 55 and the natural gas CH_FourCO trapped in zeolite and / or activated carbon₂CO and H in the presence of₂And reformed fuel with CH_FourAnd H₂O and CO and H₂Reformed into a reformed fuel with all the natural gas to CO and H₂The reformed fuel reacts with the reformed fuel, and air is sent from the air introduction pipe 64 to the compartment 55, and the reformed fuel is supplied to the engine through the intake pipe 33 and then the intake manifold 16 together with the air.
0036]
  The fuel reformer that can be applied to this gas engine is not limited to the above-described configuration, and may be configured in a simple structure as shown in FIGS. 7 and 8 showing the simplified fuel reformer 15S, the same members as those of the fuel reformer 15 shown in FIGS. 5 and 6 are denoted by the same reference numerals. The simplified fuel reformer 15S includes an exhaust pipe 30 connected in a sealed state to an inlet side opening 52 of a housing 41 via a seal member 59, a natural gas pipe 46 for introducing natural gas, a steam pipe 45, and An air introduction pipe 64 is connected, and an exhaust pipe 30, a reformed fuel passage 40 for sending reformed gas, and an air introduction pipe 64 are connected to the outlet opening 53 in a sealed state via a seal member 59, respectively. To do. In addition, a control valve device that sequentially pumps exhaust gas, natural gas, water vapor, and air, that is, an exhaust gas valve 66, a natural gas fuel valve 68, a water vapor valve 67, and an air valve 65, is provided in the compartment 55 of the rotating container 42. ing. In the simple fuel reformer 15S, a motor 51 capable of variably controlling the rotation, stop, intermittent rotation, and rotation speed of the rotating container 42 is attached to the rotating container 42 in response to a command from the controller 25. ing.
0037]
  Since the simple fuel reformer 15S is configured as described above, exhaust gas is introduced into the compartment 55 of the rotating vessel 42 through the exhaust pipe 30, and the surface of the metal porous body 43 has zeolite and / or CO in exhaust gas by activated carbon₂Is adsorbed, and then natural gas is fed into the exhaust gas.₂And CH_FourReacts with CO and H₂As well as CO₂And CH_FourReacts with CO and H₂The reaction was delayed by introducing the water vapor reformed into the reformed fuel with O and then vaporized by the heat energy of the exhaust gas into the compartment 55 through the water vapor pipe 45._FourWater vapor or H₂CO and H modified by O₂To reformed fuel, thereby converting all natural gas to CO and H₂The reformed fuel reacts with the reformed fuel, and air is sent from the air introduction pipe 64 into the compartment 55, and the reformed fuel is supplied to the engine through the intake pipe 33 and then the intake manifold 16 together with the air.
0038]
【The invention's effect】
  As described above, the gas engine having the fuel reformer according to the present invention is the main engine.combustionChamber and vicecombustionWith the communication port communicating with the chamber blocked by the sub chamber control valve,combustionSupply the natural gas reformed fuel and air to the chamber.combustionSince natural gas is supplied to the chamber,combustionNatural gas with constant properties in the chamber can be reliably ignited and combusted at a predetermined temperature.combustionMainly by the combustion flame that spewsIn the combustion chamberIt is possible to improve the thermal efficiency by reducing the combustion period of secondary combustion by propagating the mixture to the mixture of reformed fuel and air. Natural gas consists of the thermal energy of the exhaust gas and the CO in the exhaust gas.₂And CO and H effectively by reforming fuel device₂It can be reformed into reformed fuel and improve the thermal efficiency of the engine.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a gas engine having a natural gas reforming apparatus according to the present invention.
FIG. 2 is an enlarged sectional view showing a sub chamber in the gas engine of FIG.
FIG. 3 is a schematic explanatory view showing a fuel supply system in the gas engine.
FIG. 4 is a diagram showing valve timing of the gas engine.
FIG. 5 shows an example of a fuel reformer provided in the gas engine, and is a cross-sectional view taken along the line BB of FIG.
6 is a cross-sectional view taken along the line AA of FIG. 5, showing the fuel reformer of FIG.
7 is a cross-sectional view taken along the line DD of FIG. 8, showing another example of the fuel reformer provided in the gas engine.
8 shows the fuel reformer of FIG. 5, and is a cross-sectional view taken along the line CC of FIG.
[Explanation of symbols]
  1 main room
  2 Sub-room
  3 Natural gas valve
  4 cylinders
  5 piston
  8 Sub chamber control valve
  11 Cylinder block
  12 cylinder headDo
  14  Combustion chamber components
  15 Fuel reformer
  16 Intake manifold
  17 Reformed fuel valve
  18 Glow plug
  22 Natural gasRoad
  27  Contact
  30 Exhaust pipe
  33 Intake pipe
  40 Reformed fuel passage
  41 Housing
  42 Rotating container
  43 Metal porous body
  45 Steam pipe
  46 Natural gas pipe
  49 Bulkhead plate
  52 Entrance side opening
  53 Exit opening
  55 sectionsRoom
  60  Reformed fueltube
  63  Zirconia
  64 Air introduction pipe
  65 Air valve
  66 Exhaust gas valve
  67 Steam valve
  68 Natural Gas Fuel Valve

Claims (5)

A cylinder head attached to the cylinder block, a piston reciprocatingly moved in a cylinder formed on the cylinder block side, a main combustion chamber formed on the piston side, a sub-combustion chamber provided on the cylinder head, the main combustion A sub chamber control valve disposed at a communication port that communicates the chamber with the sub combustion chamber, heat energy of exhaust gas discharged from the main combustion chamber, and CO ₂ and H ₂ O are used to convert natural gas into H _2. A fuel reformer for reforming to CO and CO, a reformed fuel valve provided in a reformed fuel passage disposed in an intake pipe, and a natural gas supply passage for supplying natural gas to the auxiliary combustion chamber Natural gas valve
In order to burn the natural gas in the sub-combustion chamber, the sub-chamber control valve is opened in the latter half of the compression stroke to blow a lean mixture of air and reformed fuel from the main combustion chamber into the sub-combustion chamber. wherein the natural gas auxiliary combustion chamber is ignited and burned, wherein the gas engine comprising a Rukoto the reformed fuel is burned existing in said main combustion chamber by the combustion flames spewing from the secondary combustion chamber.   The gas engine according to claim 1, wherein a glow plug is disposed in an upper portion of the sub-combustion chamber facing the sub-chamber control valve. The fuel reformer includes a cylindrical rotary container that is rotatably supported by a cylindrical housing and is internally divided into a plurality of compartments in a rotation direction by a partition plate, and the exhaust gas from the exhaust pipe, A fuel reforming control valve for sequentially supplying water vapor from the water vapor pipe and the natural gas from the natural gas pipe to the rotary container; and an adsorbent and a catalyst are carried in the compartment of the rotary container Each of the porous metal bodies is accommodated, and an exhaust pipe, a water vapor pipe and a natural gas pipe are respectively connected to the inlet side opening and the outlet side opening of the housing, and the natural gas valve is connected to the sub-combustion chamber. The sub-chamber control valve is opened when the sub-chamber control valve is closed from the latter half of the intake stroke to the first half of the compression stroke, and the reformed fuel valve feeds the reformed fuel to the main combustion chamber. Open at, the gas engine according to claim 1 or 2 subchamber control valve consists of being configured to close the second half exhaust stroke to open in the latter half of the compression stroke. The gas engine according to any one of claims 1 to 3 , wherein portions of the sub-combustion chamber and the sub-chamber control valve that are in contact with the combustion gas are coated with ceramics such as corrosion-resistant zirconia. The fuel reformer includes a heat exchanger that recovers thermal energy of the exhaust gas, an adsorption device that adsorbs CO ₂ in the exhaust gas, and a catalyst device that reforms the natural gas into the reformed fuel. The gas engine according to any one of claims 1 to 4 , comprising:

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