JP4318928B2 - Fuel reformer and engine system incorporating the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  This invention relates to CO contained in exhaust gas.₂The present invention relates to a fuel reformer for reforming natural gas by the thermal energy of exhaust gas using an engine and an engine system incorporating the fuel reformer.
[0002]
[Prior art]
  Natural gas is mainly composed of methane (CH_Four) Is known. Fuel CH_FourBecause of its large calorific value and abundant nature, it is expected as a future alternative fuel for oil. That is, in a gas engine using natural gas as a fuel, exhaust gas is extremely clean, and in a general diesel engine, nitrogen oxides of 500 ppm or more are discharged, but in a gas engine, it is extremely low as 10 ppm or less. In addition, when a gas engine is burned, the amount of carbon dioxide emissions per energy is 30% or less less than that of petroleum fuel, which is extremely promising as a fuel for future anti-pollution engines. Conventionally, a gas engine has been developed as a cogeneration system. In the cogeneration system, motive power is extracted as electric energy by a generator, heat of exhaust gas energy is heated by a heat exchanger to make hot water, and the hot water is used for hot water supply.
[0003]
  Conventionally, an engine using natural gas as fuel is known (for example, see Patent Documents 1 and 2). However, the biggest drawback of a gas engine using natural gas is that it is difficult to burn the natural gas fuel with good fuel consumption because the natural gas fuel is a gaseous fuel. That is, in diesel combustion, fuel is blown into compressed air, but the fuel cannot be injected into the combustion chamber unless the fuel is compressed to a pressure higher than the compressed air pressure. Therefore, a lot of work is required to compress the fuel to a high pressure, and the fuel efficiency is not necessarily improved. In addition, when fuel is injected into compressed air, gas cannot be mixed well, gas cannot be ensured, fuel consumption is not improved, and nitrogen oxides are not reduced.
[0004]
  Gas engines using natural gas-modified fuel are also known. The fuel reformer incorporated in the gas engine is a natural gas main component CH._FourPyrolysis of CO and H₂To improve the thermal efficiency of the fuel and reduce the CO in the exhaust gas.₂Is used for pyrolysis, NO_XIs to suppress the occurrence of. The fuel reformer includes an exhaust gas passage body that forms an exhaust gas passage in the exhaust gas pipe, a gas fuel case through which the gas fuel flows outside the exhaust gas pipe, and a gas fuel passage formed in the gas fuel case. A porous member made of porous ceramic is disposed, and CH is formed on the surface of the porous member._FourAnd CO₂CO and H₂A catalyst having an action of converting to a reformed fuel is coated, and a heat insulating material is disposed on the outer periphery of the gas fuel pipe (see, for example, Patent Document 3).
[Patent Document 1]
          JP-A-6-108865 (first page)
[Patent Document 2]
          JP-A-6-101495 (first page)
[Patent Document 3]
          Japanese Patent Laid-Open No. 11-93777 (first page)
[0005]
[Problems to be solved by the invention]
  By the way, natural gas is thermally decomposed and reformed using exhaust gas thermal energy under the catalyst, and H₂In an engine that converts it into CO and uses reformed fuel as fuel, its thermal efficiency may be improved by 30% or more. When natural gas is reacted with carbon dioxide and reformed, the reforming reaction temperature is high, so it is difficult to sufficiently react natural gas. In particular, when the temperature of the exhaust gas is about 700 ° C. to 600 ° C. as in an engine, this tendency appears remarkably. However, the lower the exhaust gas temperature and the lower the natural gas reforming reaction temperature, the higher the feasibility of the fuel reformer. When we tested the reactivity of methane, the main component of natural gas,₂The reforming temperature by steam is lower by 200 ° C. or more than the reforming temperature by. CO₂It was found that the reforming of natural gas by 80% has a reforming rate of 80% at around 800 ° C, and the reforming of natural gas by steam has a reforming rate of 80% at 600 ° C. Therefore, it was found that the reforming of natural gas with these gases increases the reforming rate when natural gas is reacted using a catalyst that matches each of them.
[0006]
  The present inventor has developed a natural gas reforming apparatus that takes these problems into consideration and filed an application earlier (see, for example, Japanese Patent Application No. 2002-132557). The natural gas reformer is a CO 2 in exhaust gas.₂In addition, the thermal energy of the exhaust gas is used to react with natural gas using a catalyst to increase the reforming rate and increase the heat quantity of the fuel, thereby improving the thermal efficiency of the engine. The natural gas reformer is a CO 2 contained in exhaust gas.₂, H supplied from outside₂O and O contained in exhaust gas₂Using natural gas and CO in the presence of a suitable catalyst.₂, H₂Natural gas is converted into reformed fuel by sequentially reacting O.
[0007]
  However, the fuel reformer uses carbon dioxide (CO2) from the exhaust gas after combustion of the engine.₂), And the separated carbon dioxide and natural gas methane (CH_Four) In the presence of a catalyst to convert natural gas to H₂The function of reforming to reformed fuel of CO and CO, steam (H₂O) and the function of reacting methane in the presence of a catalyst are required, and these functions must be performed using a highly efficient heat exchanger. To make a device that can achieve these functions as efficiently as possible in a compact configuration, the following conditions must be cleared.
[0008]
  1. In order to recover and separate carbon dioxide from the exhaust gas, a substance that reacts with the carbon dioxide gas is arranged in a thin film, brought into contact with the exhaust gas, and adsorbed. For desorption of carbon dioxide, the adsorbed material is heated and separated.
  2. In order to efficiently execute the above reaction in a continuous state, it is necessary to prepare two sets of adsorption devices that are as compact as possible and to repeat adsorption and desorption alternately.
  3. The adsorption layer uses a porous metal material with a very large surface area, and the surface is coated with alumina, zirconia, etc. that easily adsorbs particulate matter by dipping, and the surface has an adsorption / desorption action such as lithium zirconate To attach.
  4). When an exhaust gas passage is provided at an adjacent location separated from the adsorption layer, and carbon dioxide is desorbed from the adsorbent, the high temperature exhaust gas is passed through to raise the temperature of the adsorption layer, and the carbon dioxide is removed from the adsorbent in a short time. Let go.
  5). The adsorption layer and the heat exchange layer are arranged with porous metal having different roughness welded to the partition across the partition to smoothly transfer heat.
  6). A fuel reforming chamber is arranged downstream of the pair of carbon dioxide adsorption / desorption chambers, and a high-temperature exhaust gas is allowed to flow into the carbon dioxide adsorption / desorption chamber on the side where the desorption of carbon dioxide gas proceeds. Exhaust gas is allowed to flow through the reforming passage to reform the natural gas. Since the fuel reforming passage is a continuous action, there is no temperature fluctuation.
  7. A second reforming chamber for reforming natural gas using water vapor is disposed downstream of the first reforming chamber for reforming natural gas using carbon dioxide gas, and high-temperature steam is contained in the second reforming chamber. Is introduced.
  8). The high-temperature exhaust gas exiting the fuel reforming chamber adsorbs carbon dioxide in the exhaust gas, and is sent to the other carbon dioxide adsorption / desorption chamber, where carbon dioxide is adsorbed by the adsorbent.
  9. In the high-temperature exhaust gas passage, the exhaust gas from the upstream is switched by an open / close valve, and the suction and pumping of carbon dioxide gas is performed by a pump, and the passage attached to the two carbon dioxide adsorption / desorption chambers and the open / close valve are switched. The system is implemented in accordance with the above actions.
  10. The supply of natural gas is executed by controlling the amount depending on the engine load conditions from both the carbon dioxide gas side and the water vapor side.
[0009]
[Means for Solving the Problems]
  An object of the present invention is to satisfy the above-mentioned conditions, for example, to reform natural gas by being incorporated in an engine, and CO contained in exhaust gas.₂Lithium zirconate (Li₂ZrO_Three), Adsorbed and desorbed using particles such as zeolite, and desorbed CO₂CH in natural gas using the heat energy of exhaust gas_FourCO₂When reforming with steam, CO₂, In the presence of water vapor compatible catalyst, natural gas is converted to CO and H₂It is intended to provide a fuel reforming apparatus which is thermally decomposed into reformed fuel, drives the engine using the reformed fuel, and an engine system incorporating the fuel reformer.
[0010]
  This invention uses natural gas exhaust gas heat energyIn a fuel reformer consisting of converting to reformed fuel,
  A partition wall divides a low-temperature exhaust gas passage in which a porous metal coated with an adsorbent that adsorbs carbon dioxide in the exhaust gas at a low temperature and desorbs at a high temperature and a high-temperature exhaust gas passage in which the porous metal is arranged. The first and second carbon dioxide adsorption / desorption chambers constituting a pair of packages composed of a plurality of chamber groups, and the carbon dioxide in the exhaust gas disposed downstream of the carbon dioxide adsorption / desorption chamber A reforming passage comprising a catalyst chamber for reacting the natural gas with the carbon dioxide gas to convert the natural gas into the reformed fuel in the presence of the first catalyst coated with the porous metal, and the porous metal A porous metal is coated with a first reforming chamber composed of a plurality of chamber groups partitioned by partition walls, and water vapor from the outside disposed downstream of the first reforming chamber. In the presence of a second catalyst A reforming passage formed of a catalyst layer for reacting the natural gas with the water vapor to convert the natural gas into the reformed fuel and an exhaust gas passage made of a porous metal from a plurality of chamber groups partitioned by partition walls. A second reforming chamber comprisingAnd
  The carbon dioxide adsorption / desorption chamber is separated such that the high-temperature exhaust gas passage and the low-temperature exhaust gas passage constituting the carbon dioxide adsorption / desorption passage are alternately stacked via the partition walls, and the passage is not conducted to each other. The room group,
  In the first and second reforming chambers, the porous metal constituting the exhaust gas passage and the porous metal coated with the catalyst are closely welded to the partition wall and the catalyst layer is airtight. The reforming passage is communicated by being housed in a cell of the chamber group withThe present invention relates to a fuel reforming apparatus.
[0011]
  In the fuel reformer, an exhaust pipe through which the exhaust gas from the engine flows is branched into two branch pipes, and an open / close valve is provided in each branch pipe, and the branch pipe is provided with the carbon dioxide adsorption Carbon dioxide gas extraction connected to the high temperature exhaust gas passage side of the desorption chamber, and provided with a pump and an open / close valve connected to the first reforming chamber on the low temperature exhaust gas passage side of the carbon dioxide adsorption / desorption chamber A passage is provided, and the exhaust gas flows from the downstream of the second reforming chamber and is exhausted through the low temperature exhaust gas passage.
[0012]
  Further, the exhaust gas from the engine flows into the high-temperature carbon dioxide passage of one of the carbon dioxide adsorption / desorption chambers and gives thermal energy to the low-temperature exhaust gas passage of the carbon dioxide adsorption / desorption passage. The carbon dioxide gas adsorbed on the agent is desorbed, and the desorbed carbon dioxide gas is opened in the open / close valve and the pump is driven mainly to drive the reforming of the first reforming chamber through the carbon dioxide gas extraction passage. The exhaust gas that is fed into the gas passage and flows into the exhaust gas passage of the first reforming chamber gives the thermal energy to the reforming passage and converts the natural gas supplied from the natural gas supply passage to the carbon dioxide gas. Reforming in the presence of.
[0013]
  The first reforming chamber is connected to a natural gas supply passage having an opening / closing valve in a direction perpendicular to the exhaust gas passage flowing in the axial direction, and the second reforming chamber has a water vapor having an opening / closing valve. The supply passage is connected in a direction orthogonal to the exhaust gas passage flowing in the axial direction, and each exhaust gas passage is sealed so as to ensure airtightness.
[0014]
  The exhaust gas from the exhaust gas passage of the first reforming chamber flows into the exhaust gas passage of the second reforming chamber, and from the reforming passage of the first reforming chamber to the second reforming chamber. The reformed fuel and the unreformed fuel that have flowed into the reforming passage are further reformed in the presence of steam supplied from the steam supply passage to the reforming passage of the second reforming chamber, Fuel is supplied to the engine.
[0015]
  The exhaust gas flowing out from the exhaust gas passage of the second reforming chamber flows into the low temperature exhaust gas passage of the other carbon dioxide adsorption / desorption chamber, and the carbon dioxide in the exhaust gas flowing through the low temperature exhaust gas passage. The gas is adsorbed by the adsorbent, and the exhaust gas from which the carbon dioxide gas is adsorbed and removed is supplied to the engine as exhaust gas or EGR gas through steam and a heat exchanger.
[0016]
  The fuel reformer further comprises an operation of desorbing carbon dioxide from the adsorbent attached to the porous metal in the carbon dioxide adsorption / desorption passage of one of the carbon dioxide adsorption / desorption chambers and the other. In order to alternately execute the operation of adsorbing the carbon dioxide gas to the porous metal in the carbon dioxide adsorption / desorption passage of the carbon dioxide adsorption / desorption chamber, the open / close valve of the branch pipe is alternately switched and operated. The exhaust gas from the other carbon dioxide gas adsorption / desorption chamber is fed into the high-temperature exhaust gas passage so that the carbon dioxide gas flows into the porous metal in the low-temperature exhaust gas passage of the one carbon dioxide adsorption / desorption chamber. And the desorption of the carbon dioxide gas from the porous metal in the low-temperature exhaust gas passage of the other carbon dioxide adsorption / desorption chamber is repeated every predetermined time.
[0017]
  The carbon dioxide adsorption / desorption chamber is shielded by a heat insulating layer so that the heat energy of the exhaust gas is not dissipated, and is supported on the porous metal in the carbon dioxide adsorption / desorption passage of the carbon dioxide adsorption / desorption chamber. The adsorbent is lithium zirconate particles bonded to the surface of the porous metal, and adsorbs the carbon dioxide gas in the exhaust gas when the exhaust gas has a low temperature of 350 ° C. to 500 ° C. The carbon dioxide gas is desorbed at a high temperature of 750C to 750C.
[0018]
  The first catalyst contributing to the reaction between the natural gas and the carbon dioxide gas is Pt, Ru, Rh, CeO.₂, Ni.Also,The second catalyst that contributes to the reaction between the natural gas and the water vapor is Ni, Pt, Ru, Rh.
[0019]
  Further, according to the present invention, the fuel reformer is disposed downstream of an exhaust turbine into which exhaust gas from an engine is sent, and the fuel reformer is operated after the exhaust gas from the engine has worked in the exhaust turbine. The exhaust gas is fed into the apparatus, carbon dioxide gas is adsorbed by the fuel reformer, and the exhaust gas from which the carbon dioxide gas has been removed is exhausted to the outside through a heat exchanger and partly supplied to the engine as EGR The present invention relates to an engine system.
[0020]
  Part of the natural gas is supplied to the sub chamber of the engine, and the remaining part is fed into the fuel reformer and H₂The reformed fuel is reformed into reformed fuel composed of CO and CO, and the reformed fuel is fed into the main chamber of the engine.
[0021]
  The exhaust turbine is attached to one end of a shaft, a steam turbine is attached to the other end of the shaft, a generator is disposed on the shaft, and the steam turbine is provided downstream of the fuel reformer. A part of the steam heated by the heat exchanger is sent in, and the remainder of the steam is sent to the fuel reformer and functions as the steam to reform the natural gas.
[0022]
  The electric power generated by the generator is consumed as an output for driving a compressor that sends a boost to the engine, or an output for driving the engine or an auxiliary machine.
[0023]
  The steam that has worked in the steam turbine is sent to a condenser to be converted to water, the water cools the engine oil in another heat exchanger, and the water heated by the oil is used as the fuel. It is sent to the heat exchanger downstream of the reformer and converted into steam.
[0024]
  Since this fuel reformer is configured as described above, the action of sending exhaust gas to one of the carbon dioxide adsorption / desorption chambers only switches between opening and closing of the pair of on-off valves, and carbon dioxide adsorption / desorption is performed. Sealing the separation chamber is extremely advantageous, and exhaust gas from the engine is opened to one of the carbon dioxide adsorption / desorption chambers by opening one of the open / close valves to remove the carbon dioxide adsorbed by the adsorbent. The carbon dioxide gas released and released can be fed into the reforming chamber to contribute to the reforming of natural gas, and the other open / close valve can be closed to change to the other carbon dioxide adsorption / desorption chamber. The exhaust gas, which has been cooled down due to the release of thermal energy in the pristine chamber, is sent in, the carbon dioxide in the exhaust gas is adsorbed by the adsorbent, and the exhaust gas from which the carbon dioxide has been removed is the heat downstream of the fuel reformer. Sent to the exchanger and above Of can be continuously performed these series of operation, the natural gas reforming, can be used reformed fuel to drive the engine.
  In addition, this engine system is configured as described above and incorporates the fuel reformer described above, so that natural gas fuel can be used effectively, the output can be increased, and the generator can effectively generate electric power, The total thermal efficiency can be greatly increased.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of a fuel reformer and an engine system incorporating the same according to the present invention will be described below with reference to the drawings. This fuel reformer is applied by being incorporated in an engine system that converts natural gas into reformed fuel using the thermal energy of exhaust gas, and supplies the reformed fuel to the engine for combustion.
[0026]
  In particular, the fuel reformer 1 according to the present invention includes carbon dioxide (CO) contained in exhaust gas (EG) discharged from the engine 2.₂) And water vapor supplied from the outside of the engine 2 (H₂O) is used to sequentially react natural gas (CNG) with carbon dioxide and water vapor in the presence of a catalyst that matches carbon dioxide and water vapor to convert the natural gas into H.₂And converted into a reformed fuel of CO. The fuel reformer 1 is a main component of natural gas used for the engine 2._FourH₂The fuel is reformed into a reformed fuel of CO and CO to improve the thermal efficiency, and the structure is simple, the sealing property is good, and the size can be reduced. In addition, this engine system incorporates the fuel reformer 1 to effectively use the thermal energy of the exhaust gas, and the above-mentioned thermal energy and the CO contained in the exhaust gas.₂The thermal efficiency can be improved by using a reformed fuel obtained by reforming natural gas by capturing and utilizing.
[0027]
  In the fuel reformer 1, as the adsorbent 73 that adsorbs and desorbs carbon dioxide from the exhaust gas, for example, lithium zirconate (Li) coated on the surface of the porous metal 88 in the low-temperature exhaust gas passage 52 is used.₂Zr_FourO_Three) And / or zeolite or the like, and lithium zirconate is particularly effective. The catalyst 93 (first catalyst) that contributes to the reaction between natural gas and carbon dioxide is dispersed on the surface of the porous metal 90 in the natural gas / carbon dioxide passage in the first reforming chamber 22, that is, the reforming passage 57. Deposited platinum (Pt), ruthenium (Ru), rhodium (Rh), cerium oxide (CeO)₂), Nickel (Ni) and other fine particles. The catalyst 94 (second catalyst) that contributes to the reaction between natural gas and water vapor is nickel that is dispersed and attached to the surface of the porous metal 92 in the natural gas / water vapor passage in the second reforming chamber 23, that is, the reforming passage 59. Fine particles such as (Ni), platinum (Pt), ruthenium (Ru), rhodium (Rh).
[0028]
  The fuel reformer 1 is configured so that the natural gas reforming temperature is increased in descending order.₂, Then water vapor (H₂O) was used for the reaction to greatly improve the reforming rate. For example, in the first reforming chamber 22, CO is used with Pt, Ru, Ni as a catalyst.₂The total reforming rate of natural gas is set to 50% assuming that it has reacted under the worst conditions. Since the first reforming chamber 22 is carbon dioxide gas reforming, the carbon dioxide adsorption / desorption chambers 20 and 21 upstream thereof are CO.₂An adsorbent 73 that adsorbs the water is required. CO₂Various types of adsorption have been proposed. As the adsorbent 73, zeolite and / or lithium zirconate have excellent characteristics. Therefore, in the fuel reformer 1, the CO contained in the exhaust gas at a low temperature is used.₂Is adsorbed by adsorbent 73 and adsorbed CO₂Is removed from the adsorbent 73 by the heat energy of the high-temperature exhaust gas, and the released carbon dioxide gas is sent to the reforming chamber and used for reforming the natural gas.
  The chemical formula for lithium zirconate is as follows.
  When the exhaust gas temperature is 350 ° C. to 500 ° C. (for example, around 300 ° C.), carbon dioxide in the exhaust gas is adsorbed.
      Li₂ZrO_Three+ CO₂→ ZrO₂+ Li₂CO_Three
  Further, when the exhaust gas temperature is 700 ° C. to 750 ° C. (for example, around 700 ° C.), the carbon dioxide gas adsorbed by the adsorbent is desorbed.
      ZrO₂+ Li₂CO_Three→ Li₂ZrO_Three+ CO₂
  That is, when the exhaust gas temperature is around 300 ° C., Li₂ZrO_ThreeIs CO₂Reacts with zirconium oxide lithium carbonate, and when the exhaust gas temperature is around 700 ° C, lithium zirconate and CO₂become.
[0029]
  The fuel reformer 1 includes zeolite and / or lithium zirconate dispersed and attached to the surface of the porous metal in the carbon dioxide adsorption / desorption chamber 21 (20) and carbon dioxide (CO2) in the exhaust gas.₂) Is caused to flow from the second reforming chamber 23 into the exhaust gas passage 52 of the carbon dioxide adsorption / desorption chamber 21 (20). In the carbon dioxide adsorption / desorption chamber 21 (20), the adsorbent 73 adsorbs carbon dioxide in the exhaust gas. In the other carbon dioxide adsorption / desorption chamber 20 (21), high-temperature exhaust gas passes through the exhaust gas passage 51 filled with porous metal, and is adsorbed by the adsorbent 73.₂Is released from the adsorbent 73.
[0030]
  An embodiment of an engine system according to the present invention will be described with reference to FIG. The exhaust gas discharged from the engine 2 is sent to the exhaust turbine 3 through the exhaust pipe 76. The exhaust gas that has worked in the exhaust turbine 3 is sent to the fuel reformer 1 described later through the exhaust pipe 26. The high temperature exhaust gas is adsorbed with carbon dioxide in the exhaust gas in the fuel reformer 1 and consumes thermal energy to reform the natural gas. The low-temperature exhaust gas from which carbon dioxide gas has been removed by working in the fuel reformer 1 is sent to the heat exchanger 6 through the exhaust gas passage 47. The low-temperature exhaust gas is heat-exchanged with water in the heat exchanger 6, further lowered in temperature, discharged to the exhaust gas passage 77, exhausted to the outside by switching to the switching valve 12, or passed through the EGR passage 78. To the EGR device 14. The EGR device 14 controls the flow rate of the exhaust gas to mix it with air, and then the air and the EGR gas are supplied to the engine 2 through the boost passage 86.
[0031]
  Part of the natural gas is sent from the natural gas supply source 7 to the sub chamber (not shown) of the engine 2 through the natural gas supply passage 79 and contributes to ignition combustion, particularly ignition in the sub chamber. Further, most of the natural gas is fed into the fuel reformer 1 through the natural gas supply passage 42, and the natural gas is H 2 in the presence of the catalysts 93 and 94 together with carbon dioxide and then water vapor.₂The fuel is reformed into the reformed fuel of CO and fed into the main chamber (not shown) of the engine 2 through the reformed fuel supply passage 46 and ignited and combusted. At this time, the natural gas supply passage 42 and the reformed fuel supply passage 46 pass through the heat exchanger 15, and the natural gas is supplied with the thermal energy of the reformed fuel and the temperature thereof is increased and supplied to the fuel reformer 1. The
[0032]
  The exhaust turbine 3 is attached to one end of a shaft 19, the steam turbine 5 is attached to the other end of the shaft 19, and the generator 4 is disposed on the shaft 19. A part of the steam heated by the heat exchanger 6 provided downstream of the fuel reformer 1 is sent to the steam turbine 5 to drive the steam turbine 5. Further, the remaining steam from the heat exchanger 6 is sent to the fuel reformer 1, and the steam functions as a substance that reforms natural gas. Electric power generated by the generator 4 is consumed as an output 13 of the engine 2, the water pump 11, the compressor 10, an auxiliary machine, or the like, driving the compressor 10 that sends boost to the engine 2. The compressor 10 is driven by a motor 18 that is driven by the electric power generated by the generator 4.
[0033]
  Further, the steam that has worked in the steam turbine 5 is sent to the condenser 8 through the steam passage 80 and converted into water, and the water cools the oil of the engine 2 in the heat exchanger 9 and the water heated by the oil. Is sent to the heat exchanger 6 downstream of the fuel reformer 1 and converted into steam. The oil heated by cooling the engine 2 is sent to the heat exchanger 9 through the oil circulation path 84, the oil itself is cooled by the heat exchanger 9, and the water sent through the water passage 82 by the water pump 11 is heated. And converted to hot water or steam. The condenser 8 is supplied with water from the water supply source 17 through the water passage 81, and functions to cool the steam / water discharged from the steam turbine 5 by the water. The water cooled by the condenser 8 is supplied to the heat exchanger 9 through the water passage 82 and then to the heat exchanger 6 through the water / steam passage 85 by driving the water pump 11, and converted into high-temperature steam by the heat exchanger 6. Converted. A part of the steam converted by the heat exchanger 6 is sent to the fuel reformer 1 through the steam supply passage 43, and most of the steam is sent to the steam turbine 5 through the steam passage 83. That is, the steam turbine 5, the condenser 8, and the heat exchangers 9 and 6 constitute a kind of Rankine cycle.
[0034]
  Next, the fuel reformer 1 incorporated in the engine system will be described with reference to FIGS. The fuel reformer 1 includes a partition wall 32 on which a porous metal coated with an adsorbent 73 that adsorbs carbon dioxide in exhaust gas disposed upstream of the exhaust gas flow at low temperatures and desorbs at high temperatures is disposed. The first and second carbon dioxide adsorption / desorption chambers 20 and 21 and the carbon dioxide adsorption / desorption chambers 20 and 21 constituting the paired compartmented packages are porous using carbon dioxide in the exhaust gas. The first reforming chamber 22 for converting natural gas into reformed fuel by reacting natural gas and carbon dioxide in the presence of the first catalyst 93 coated with the porous metal 90, and downstream of the first reforming chamber 22 A second reforming chamber for converting natural gas into reformed fuel by reacting natural gas with water vapor in the presence of the second catalyst 94 coated on the porous metal 92 using water vapor from the outside disposed in 23.
[0035]
  An exhaust pipe 26 through which exhaust gas from the engine 2 flows is branched into two branch pipes 27 and 28, and open / close valves 29 and 30 are provided in the branch pipes 27 and 28, respectively. The branch pipes 27 and 28 are connected to the carbon dioxide adsorption / desorption chambers 20 and 21, respectively. The carbon dioxide adsorption / desorption chambers 20 and 21 include carbon dioxide gas passages 49 and 50 including pumps 24 and 25 and an exhaust gas passage 31. And is connected to the first reforming chamber 22. The carbon dioxide adsorption / desorption chambers 20 and 21 are configured such that exhaust gas flows through the carbon dioxide passages 49 and 50 by opening and closing valves 69 and 70 provided at the outlets. Carbon dioxide gas introduction valves 67 and 68 are provided in the carbon dioxide gas passages 49 and 50. When the carbon dioxide gas introduction valves 67 and 68 are opened by the control command and the pumps 24 and 25 are operated, the carbon dioxide gas flows from the carbon dioxide gas adsorption / desorption chambers 20 and 21 through the carbon dioxide gas passages 49 and 50 into the first reforming chamber. 22 is sent.
[0036]
  As shown in FIG. 3, the carbon dioxide adsorption / desorption chambers 20 and 21 constitute a package composed of a plurality of chamber groups, a plurality of exhaust gas passages 51 in which a porous metal 87 is disposed in the chamber, A plurality of carbon dioxide adsorbing / desorbing passages 52 in which a porous metal 88 is disposed in the room are alternately stacked via partition walls 55. In FIG. 3, the passage where the shielding plate exists is shown without hatching, the passage through which gas passes is hatched, and the porous metal 87, 88 and the adsorbent 73 attached to the porous metal 87, 88 are exposed. The catalyst part inlets 74 and 75 which are are shown. The carbon dioxide adsorption / desorption chambers 20 and 21 are structurally identical in package, and high-temperature exhaust gas from the branch pipes 27 and 28 passes through the high-temperature exhaust gas passages of the carbon dioxide adsorption / desorption chambers 20 and 21. The only difference is whether the carbon dioxide gas is desorbed or adsorbed to the adsorbent 73 depending on whether it is sent to 51 or low temperature exhaust gas is sent from the exhaust gas passages 33 and 34 to the low temperature exhaust gas passage 52. is there. When high-temperature exhaust gas from the engine 2 is fed into the high-temperature exhaust gas passage 51 of the carbon dioxide adsorption / desorption chambers 20 and 21 through the branch pipes 27 and 28, the on-off valves 29 and 30 are opened (in FIG. When the low-temperature exhaust gas is sent to the low-temperature exhaust gas passage 52 through the exhaust gas passages 33 and 34, the on-off valves 29 and 30 are closed (the on-off valve 29 is closed in FIG. 2).
[0037]
  As shown in FIG. 4, the first and second reforming chambers 22 and 23 are configured in a plurality of chamber groups, and a plurality of exhaust gases in which porous metals 89 to 92 are respectively disposed in the chamber. The passages 56 and 58 and the reforming passages 57 and 59 formed of the catalyst chamber are alternately stacked via the partition wall 60. Further, the catalysts 93 and 94 are accommodated in the cells in the reforming passages 57 and 59. In FIG. 4, the region where the gas cannot pass due to the presence of the shielding plate is shown without hatching, and the passage through which the gas passes is hatched, so that the porous metal 87 to 92 and the catalysts 93 and 94 are accommodated. Catalyst part inlets 74 and 75 are opened in the mass passages 57 and 59.
[0038]
  A natural gas supply passage 42 having an opening / closing valve 44 is connected to the first reforming chamber 22 in a direction orthogonal to an exhaust gas passage 56 that flows in the axial direction. Further, a steam supply passage 59 provided with an opening / closing valve 45 is connected to the second reforming chamber 23 in a direction orthogonal to the exhaust gas passage 58 flowing in the axial direction. Each of the passages is sealed so as to form a large number of chamber groups, that is, cell groups partitioned from each other so as to ensure airtightness.
[0039]
  For example, as shown in FIG. 2, the exhaust gas from the engine 2 flows into a high-temperature carbon dioxide gas passage 51 of one carbon dioxide adsorption / desorption chamber 20 with an open / close valve 29 opened to convert the thermal energy into carbon dioxide gas. Carbon dioxide gas supplied to the adsorption / desorption passage 52 and adsorbed on the adsorbent 73 is desorbed, and the desorbed carbon dioxide gas is sent into the reforming passage 57 of the first reforming chamber 22. Further, the exhaust gas flowing into the exhaust gas passage 56 of the first reforming chamber 22 gives thermal energy to the natural gas / carbon dioxide passage, that is, the reforming passage 57, and the natural gas supplied from the natural gas supply passage 42 is converted into carbon dioxide gas. Reforming in the presence of.
[0040]
  The exhaust gas flowing out from the exhaust gas passage 56 of the first reforming chamber 22 flows into the exhaust gas passage 58 of the second reforming chamber 23, and the reformed fuel and unreformed fuel that flow out of the first reforming chamber 22. The exhaust gas that has flowed into the steam / carbon dioxide gas passage of the second reforming chamber 23, that is, the reforming passage 59, and the exhaust gas that has flowed into the exhaust gas passage 57 of the second reforming chamber 23 gives thermal energy to the reforming passage 59. The unreformed fuel is reformed into the reforming passage 59 of the second reforming chamber 23 in the presence of the steam supplied from the steam supply passage 43, and the reformed fuel is supplied to the engine 2.
[0041]
  The low-temperature exhaust gas flowing out from the exhaust gas passage 57 of the second reforming chamber 23 flows into the low-temperature exhaust gas passage 52 of the other carbon dioxide adsorption / desorption chamber 21. The exhaust gas that has become low temperature due to the release of heat energy is adsorbed by the adsorbent 73 in the presence of the catalyst, and the exhaust gas from which carbon dioxide has been adsorbed and eliminated is exhausted to the outside through the heat exchanger 6 or The gas is fed into the EGR passage 78 and supplied to the engine 2 as EGR gas.
[0042]
  Carbon dioxide is desorbed from the carbon dioxide adsorption / desorption passage in one carbon dioxide adsorption / desorption chamber 20, that is, the porous metal 88 in the high-temperature exhaust gas passage 52, and the carbon dioxide adsorption / desorption passage in the other carbon dioxide adsorption / desorption chamber 21. Carbon dioxide gas is adsorbed on the 52 porous metal 88. Here, the open / close valves 29 and 30 of the branch pipes 27 and 28 are switched, the exhaust gas from the engine 2 is sent into the exhaust gas passage 51 of the other carbon dioxide adsorption / desorption chamber 21, and the other carbon dioxide adsorption / desorption chamber 21. Carbon dioxide adsorption / desorption passage, that is, carbon dioxide gas is desorbed from the porous metal 88 in the low-temperature exhaust gas passage 52, and low-temperature exhaust gas is introduced into one carbon dioxide adsorption / desorption chamber 20 to produce a carbon dioxide adsorption / desorption passage. The 52 porous metals 88 are operated to adsorb carbon dioxide gas.
[0043]
  The carbon dioxide adsorption / desorption chambers 20, 21 are shielded by a heat insulating layer so that the heat energy of the exhaust gas is not dissipated, and the carbon dioxide adsorption / desorption chambers 52, 21 have a porous metal 88 in the carbon dioxide adsorption / desorption passage 52. The adsorbent 73 carried is lithium zirconate particles bonded to the surface of the porous metal 88, and adsorbs carbon dioxide in the exhaust gas when the exhaust gas is at a low temperature of 350 ° C. to 500 ° C. Carbon dioxide gas is desorbed at a high temperature of 700 ° C. to 750 ° C.
[0044]
  FIG. 5 shows a specific embodiment of the fuel reformer 1. In FIG. 5, the configuration is basically the same as that of the fuel reformer 1 shown in FIG. 2, and thus the same components are denoted by the same reference numerals and redundant description is omitted. The fuel reformer 1 is accommodated in the outer housing 64 as a whole. The on-off valves 29 and 30 are configured to be opened and closed by actuators 65 and 66, respectively, according to a command from the controller. The carbon dioxide gas introduction valves 67 and 68 are configured to be opened and closed by solenoids 71 and 72, respectively, in accordance with a controller command.
[0045]
  As for the fuel reformer 1, the gas flow is configured as shown in FIGS. The low-temperature exhaust gas is supplied from the exhaust gas passages 33 and 34 to the low-temperature exhaust gas passage 52 of the carbon dioxide adsorption / desorption chambers 20 and 21 through the collecting portion 54 provided on the side of the carbon dioxide adsorption / desorption chambers 20 and 21. The The exhaust gas from which the carbon dioxide gas has been removed passes from the low temperature exhaust gas passage 52 of the carbon dioxide adsorption / desorption chambers 20 and 21 to the exhaust gas passage 35 through the collecting portion 53 provided on the side of the carbon dioxide adsorption / desorption chambers 20 and 21. , 36. Further, the natural gas supply passage 42 is connected to a collecting portion 61 provided on the side of the first reforming chamber 22, and the natural gas passes from the natural gas supply passage 42 to the reforming passage 57 stacked through the collecting portion 61. be introduced. The steam supply passage 43 is connected to a collecting portion 62 provided on the side of the second reforming chamber 23, and steam is introduced from the steam supply passage 43 through the collecting portion 62 to the reforming passage 59 stacked. Further, the reformed fuel is sent from the reforming passage 59 of the second reforming chamber 23 to the reformed fuel supply passage 46 through the collecting portion 63 provided on the side of the second reforming chamber 23.
[0046]
【The invention's effect】
  Since the fuel reformer and the engine system according to the present invention are configured as described above, the fuel reformer itself is very compact, and the carbon dioxide adsorption / desorption chamber does not rotate or move. Therefore, the sealing performance can be improved. In addition, CH, which is the main component of natural gas_FourCO and H with the aid of a catalyst in the presence of carbon dioxide and then water vapor₂The reformed fuel is extremely efficiently reformed. In addition, as an adsorbent, carbon dioxide gas can be adsorbed from low-temperature exhaust gas only by attaching lithium zirconate particles to the surface of the porous metal, and heat energy is transferred from high-temperature exhaust gas. The carbon dioxide gas can be desorbed only with this. In addition, the engine system incorporates the fuel reformer described above, so that the reformed fuel obtained by reforming natural gas can be supplied to the main chamber and burned in the engine to improve the thermal efficiency. In addition, ignition and combustion can be performed smoothly by supplying natural gas to the sub chamber.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing an embodiment of an engine system according to the present invention.
FIG. 2 is a schematic explanatory view showing a fuel reformer incorporated in the engine system of FIG. 1;
3 is a schematic perspective view showing a carbon dioxide adsorption / desorption chamber in the fuel reformer of FIG. 2; FIG.
4 is a schematic perspective view showing a first reforming chamber and a second reforming chamber in the fuel reformer of FIG. 2; FIG.
FIG. 5 is a schematic explanatory view showing a specific embodiment of the fuel reformer according to the present invention.
[Explanation of symbols]
  1 Fuel reformer
  2 Engine
  3 Exhaust turbine
  4 Generator
  5 Steam turbine
  6 Heat exchanger (the downstream of the fuel reformer)
  7 Natural gas supply sources
  8 Condenser
  9,15 heat exchanger
  10 Compressor
  11, 24, 25 pump
  12 Switching valve (for exhaust gas)
  13 Output (auxiliary machine etc.)
  14 EGR equipment
  16, 17 Water source
  18 Motor
  19 Shaft
  20, 21 Carbon dioxide adsorption / desorption chamber
  22 First reforming chamber
  23 Second reforming chamber
  26 Exhaust pipe
  27, 28 Branch pipe
  29, 30, 38, 39, 40, 41, 44, 45 Open / close valve
  31, 33, 34, 35, 36, 37, 47 Exhaust gas passage
  32, 55, 60 Bulkhead
  42 Natural gas supply passage
  43 Steam supply passage
  46 Reformed fuel supply passage (to engine)
  48 divider
  49, 50 Carbon dioxide supply passage
  51 High-temperature exhaust gas passage (carbon dioxide adsorption / desorption chamber)
  52 Low-temperature exhaust gas passage (carbon dioxide adsorption / desorption chamber)
  56 Exhaust gas passage (for high-temperature exhaust gas in the first reforming chamber)
  57 Natural gas / CO2 passage (reforming passage)
  58 Exhaust gas passage (for high-temperature exhaust gas in the second reforming chamber)
  59 Steam / CO2 passage (reformation passage)
  64 Outer housing
  67,68 Carbon dioxide gas introduction valve
  69,70 Valve for exhaust gas
  73 Adsorbent
  74,75 Catalyst inlet
  87, 88, 89, 90, 91, 92 Porous metal
  93,94 catalyst

Claims (15)

In a fuel reformer comprising converting natural gas into reformed fuel using the thermal energy of exhaust gas ,
A partition wall divides a low-temperature exhaust gas passage in which a porous metal coated with an adsorbent that adsorbs carbon dioxide in the exhaust gas at a low temperature and desorbs at a high temperature and a high-temperature exhaust gas passage in which the porous metal is arranged. The first and second carbon dioxide adsorption / desorption chambers constituting a pair of packages composed of a plurality of chamber groups, and the carbon dioxide in the exhaust gas disposed downstream of the carbon dioxide adsorption / desorption chamber A reforming passage comprising a catalyst chamber for reacting the natural gas with the carbon dioxide gas to convert the natural gas into the reformed fuel in the presence of the first catalyst coated with the porous metal, and the porous metal A porous metal is coated with a first reforming chamber composed of a plurality of chamber groups partitioned by partition walls, and water vapor from the outside disposed downstream of the first reforming chamber. In the presence of a second catalyst A reforming passage formed of a catalyst layer for reacting the natural gas with the water vapor to convert the natural gas into the reformed fuel and an exhaust gas passage made of a porous metal from a plurality of chamber groups partitioned by partition walls. A second reforming chamber is provided ,
The carbon dioxide adsorption / desorption chamber is separated such that the high-temperature exhaust gas passage and the low-temperature exhaust gas passage constituting the carbon dioxide adsorption / desorption passage are alternately stacked via the partition walls, and the passage is not conducted to each other. The room group is composed of
In the first and second reforming chambers, the porous metal constituting the exhaust gas passage and the porous metal coated with the catalyst are closely welded to the partition wall and the catalyst layer is airtight. A fuel reforming apparatus, wherein the reforming passage is communicated with a chamber of the chamber group . The exhaust pipe through which the exhaust gas from the engine flows is branched into two branch pipes, each of which has an open / close valve, and the branch pipe is the high-temperature exhaust gas passage of the carbon dioxide adsorption / desorption chamber. A carbon dioxide gas extraction passage having a pump communicating with the first reforming chamber and an open / close valve is provided on the low temperature exhaust gas passage side of the carbon dioxide adsorption / desorption chamber. 2. The fuel reformer according to claim 1, wherein the fuel reformer is discharged from the downstream of the second reforming chamber and discharged through the low-temperature exhaust gas passage. The exhaust gas from the engine flows into the high-temperature carbon dioxide passage of one of the carbon dioxide adsorption / desorption chambers and gives thermal energy to the low-temperature exhaust gas passage of the carbon dioxide adsorption / desorption passage to the adsorbent. The adsorbed carbon dioxide gas is desorbed, and the desorbed carbon dioxide gas is opened in the open / close valve and the pump is mainly driven to drive the reforming passage of the first reforming chamber through the carbon dioxide extraction passage. The exhaust gas flowing into the exhaust gas passage of the first reforming chamber gives the thermal energy to the reforming passage, and the natural gas supplied from the natural gas supply passage is converted into the presence of the carbon dioxide gas. The fuel reformer according to claim 2 , wherein reforming is performed below. The first reforming chamber is connected to a natural gas supply passage having an opening / closing valve in a direction perpendicular to the exhaust gas passage flowing in the axial direction, and the second reforming chamber has a water vapor having an opening / closing valve. supply path connected in a direction orthogonal to the exhaust gas passage flowing in the axial direction, according to claim 1 or 2 wherein each said exhaust gas passage, characterized in that it is sealed so that air tightness is ensured Fuel reformer. The exhaust gas from the exhaust gas passage of the first reforming chamber flows into the exhaust gas passage of the second reforming chamber, and from the reforming passage of the first reforming chamber to the second reforming chamber. wherein the reformed fuel and un-reformed fuel flowing into the reforming passage is further modified in the presence of steam supplied from the steam supply passage to the reforming passage of the second reforming chamber, the reforming of The fuel reformer according to any one of claims 1 to 4 , wherein fuel is supplied to the engine. The exhaust gas flowing out from the exhaust gas passage of the second reforming chamber flows into the low temperature exhaust gas passage of the other carbon dioxide adsorption / desorption chamber, and the carbon dioxide in the exhaust gas flowing through the low temperature exhaust gas passage. gas is adsorbed by the adsorbent, according to claim 1 to 5 wherein the carbon dioxide gas, characterized in that to be supplied to the engine as exhaust or EGR gas to the outside through the exhaust gas steam and heat exchangers eliminated adsorbed serial mounting of the fuel reformer any to one of. The operation of desorbing carbon dioxide from the adsorbent adhering to the porous metal in the carbon dioxide adsorption / desorption passage in one carbon dioxide adsorption / desorption chamber and the carbon dioxide in the other carbon dioxide adsorption / desorption chamber In order to alternately perform the operation of adsorbing the carbon dioxide gas to the porous metal in the gas adsorption / desorption passage, the opening and closing valves of the branch pipes are alternately switched to operate the exhaust gas from the engine on the other side. The carbon dioxide gas is fed into the high-temperature exhaust gas passage of the carbon dioxide adsorption / desorption chamber, thereby adsorbing the carbon dioxide gas to the porous metal in the low-temperature exhaust gas passage of one of the carbon dioxide adsorption / desorption chambers, and the other carbon dioxide gas The fuel according to any one of claims 1 to 6 , wherein desorption of the carbon dioxide gas from the porous metal in the low-temperature exhaust gas passage of the adsorption / desorption chamber is repeated every predetermined time. Material reformer. The carbon dioxide adsorption / desorption chamber is shielded by a heat insulating layer so that the heat energy of the exhaust gas is not dissipated, and is supported on the porous metal in the carbon dioxide adsorption / desorption passage of the carbon dioxide adsorption / desorption chamber. The adsorbent is lithium zirconate particles bonded to the surface of the porous metal, and adsorbs the carbon dioxide gas in the exhaust gas when the exhaust gas has a low temperature of 350 ° C. to 500 ° C. The fuel reformer according to any one of claims 1 to 7 , wherein the carbon dioxide gas is desorbed at a high temperature of 750C to 750C. Said first catalyst contributes to the reaction between the carbon dioxide and the natural gas, Pt, Ru, Rh, fuel according to any one of claims 1-8, characterized in that the CeO _2, Ni Reformer. The fuel reformer according to any one of claims 1 to 9 , wherein the second catalyst contributing to the reaction between the natural gas and the water vapor is Ni, Pt, Ru, or Rh. The fuel reformer according to any one of claims 1 to 10 , wherein the exhaust gas from the engine is disposed downstream of an exhaust turbine to which the exhaust gas is sent, and the exhaust gas from the engine works in the exhaust turbine. The exhaust gas is fed into the fuel reformer, and the exhaust gas is adsorbed with carbon dioxide by the fuel reformer, and the exhaust gas from which the carbon dioxide is excluded is exhausted to the outside through a heat exchanger and partially Is supplied to the engine as EGR. Part of the natural gas is supplied to the sub chamber of the engine, and the remaining part is sent to the fuel reformer to be reformed into reformed fuel composed of H ₂ and CO. The reformed fuel is the main fuel of the engine. The engine system according to claim 11 , wherein the engine system is fed into a chamber. The exhaust turbine is attached to one end of a shaft, a steam turbine is attached to the other end of the shaft, a generator is disposed on the shaft, and the steam turbine is provided downstream of the fuel reformer. A part of the steam heated by the heat exchanger is sent, and the remainder of the steam is sent to the fuel reformer and functions as the steam for reforming the natural gas. The engine system according to 11 or 12 . 14. The engine system according to claim 13 , wherein the electric power generated by the generator is consumed as an output for driving a compressor that sends boost to the engine, or an output for driving the engine or an auxiliary machine. . The steam that has worked in the steam turbine is sent to a condenser to be converted to water, the water cools the engine oil in another heat exchanger, and the water heated by the oil is used as the fuel. The engine system according to claim 13 or 14 , wherein the engine system is sent to the heat exchanger downstream of the reformer and converted into steam.

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