Synthetic fuel generation system

Abstract

A synthetic fuel generation system 1 according to the present invention comprises: a solid oxide electrolysis cell 10 to which raw material gas 2 and raw material steam 3 are supplied; a post reactor 11 that generates a synthetic fuel 4 from generated gas 10a from the solid oxide electrolysis cell 10; and a first condenser 12 that condenses the generated gas 10a from the solid oxide electrolysis cell 10 by exchanging heat with the raw material gas 2 and the raw material steam 3 supplied to the solid oxide electrolysis cell 10.

Description

Synthetic Fuel Generation System

[0001] The present invention relates to a synthetic fuel production system for producing synthetic fuels, such as methane.

[0002] As disclosed in Non-Patent Document 1 below, the production of synthetic fuels such as methane using a solid oxide electrolysis cell has been studied. Non-Patent Document 1 proposes a system in which a raw material gas and raw material vapor are supplied to a solid oxide electrolysis cell, and the product gas from the solid oxide electrolysis cell is supplied to a methane generator, and methane is produced in the methane generator. An air-cooled drain is disposed between the solid oxide electrolysis cell and the methane generator, and moisture in the product gas is removed by cooling the product gas from the solid oxide electrolysis cell in the drain.

[0003] Atsushi Maeda et al., "SOEC-type methane mixed gas production system using co-electrolysis and study of supplying the produced gas to city gas pipelines," Fuel Cell Vol. 17 No. 1 2017, pp. 81-89

[0004] In the conventional synthetic fuel production system described above, the product gas from the solid oxide electrolysis cell is cooled by an air-cooled drain, which dissipates heat from the product gas into the atmosphere, leaving room for improvement in the energy efficiency of the entire system.

[0005] The present invention has been made to solve the above-mentioned problems, and one of its objects is to provide a synthetic fuel production system that can improve the energy efficiency of the entire system.

[0006] Item 1. In one embodiment, the present invention relates to a synthetic fuel production system including a solid oxide electrolysis cell to which a feed gas and a feed steam are supplied, a post-reactor that produces a synthetic fuel from the product gas of the solid oxide electrolysis cell, and a first condenser that condenses the product gas of the solid oxide electrolysis cell by heat exchange with the feed gas and the feed steam supplied to the solid oxide electrolysis cell.

[0007] Item 2. The present invention may relate to the synthetic fuel production system according to Item 1, further comprising a first heater for heating the raw material gas and raw material steam at the outlet side of the first condenser for the raw material gas and raw material steam.

[0008] Item 3. The present invention may relate to the synthetic fuel production system according to Item 2, further comprising a first heating control device that detects the temperatures of the raw material gas and raw material steam at the outlet side of the first condenser for the raw material gas and raw material steam, and controls the amount of heating of the raw material gas and raw material steam by the first heater.

[0009] Item 4. The present invention may relate to the synthetic fuel production system according to any one of Items 1 to 3, further comprising a second condenser that is disposed on the inlet side of the first condenser for the raw material steam and condenses the synthetic fuel from the subsequent reactor by heat exchange with raw material water that is a raw material for the raw material steam.

[0010] Item 5. The present invention may relate to the synthetic fuel production system according to any one of Items 1 to 4, further comprising an evaporator having a second heater, disposed on the inlet side of the first condenser for the raw material steam, and evaporating raw material water, which is a raw material for the raw material steam, using heat generated in a downstream reactor and heating by the second heater to generate raw material steam.

[0011] Item 6. The present invention may relate to the synthetic fuel production system according to Item 5, further comprising a second heating control device that detects the heat generated in the downstream reactor and / or the amount of raw material steam generated at the outlet side of the raw material steam evaporator, and controls the amount of heating of the raw material water by the second heater.

[0012] According to one embodiment of the synthetic fuel production system of the present invention, the first condenser condenses the product gas from the solid oxide electrolysis cell by heat exchange with the feed gas and feed steam supplied to the solid oxide electrolysis cell. This allows the heat of the product gas to be used to preheat the feed gas and feed steam, improving the energy efficiency of the entire system compared to when the heat of the product gas is released into the atmosphere.

[0013] 1 is a block diagram illustrating a synthetic fuel production system 1 according to an embodiment of the present invention.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and the components can be modified and embodied without departing from the spirit of the present invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components of different embodiments may be appropriately combined.

[0015] FIG. 1 is a block diagram showing a synthetic fuel production system 1 according to an embodiment of the present invention. The synthetic fuel production system 1 shown in FIG. 1 is a system for producing a synthetic fuel 4 from a feed gas 2 and a feed steam 3. The synthetic fuel 4 may be a hydrocarbon such as methane (CH4). By producing a mixture of various hydrocarbons and adjusting it in a downstream process such as fractional distillation, a fuel that meets the specifications for gasoline, diesel, kerosene, or aviation fuel may be produced. In this embodiment, a description will be given of methane being produced as the synthetic fuel 4. When methane is produced as the synthetic fuel 4, hydrogen (H2) and carbon dioxide (CO2) may be used as the feed gas 2.

[0016] The synthetic fuel production system 1 of this embodiment includes a solid oxide electrolysis cell 10 , a post-reactor 11 , and a first condenser 12 .

[0017] A raw material gas 2 and raw material vapor 3 are supplied to a solid oxide electrolysis cell (SOEC) 10. The solid oxide electrolysis cell 10 can generate a product gas 10a containing hydrogen (H) and carbon monoxide (CO) based on the reaction shown below. This reaction is an endothermic reaction: 3H2O + CO2 → CO + 3H2 + 2O2

[0018] The solid oxide electrolysis cell 10 can have various configurations. For example, the solid oxide electrolysis cell 10 may have an anode support (Ni-YSZ), an active layer (Ni-YSZ), an electrolyte (YSZ), an intermediate layer (GDC), a cathode, (LSCF-GDC), and a separator (Fe-Cr).

[0019] The post-reactor 11 produces synthetic fuel 4 from the product gas 10a of the solid oxide electrolysis cell 10. The production of synthetic fuel 4 in the post-reactor 11 may be based on the following reaction, which is an exothermic reaction: 3H + CO → H O + CH

[0020] The downstream reactor 11 can have various configurations, for example, it may have a heat exchanger fixed bed, a circulating fluidized bed, or a slurry bed.

[0021] Here, the product gas 10a from the solid oxide electrolysis cell 10 contains moisture (unreacted raw material vapor 3), and it is preferable to reduce the amount of moisture in the product gas 10a before the product gas 10a is introduced into the subsequent-stage reactor 11.

[0022] The first condenser 12 condenses the product gas 10a from the solid oxide electrolysis cell 10 (lowers the temperature of the product gas 10a) through heat exchange with the raw material gas 2 and raw material vapor 3 supplied to the solid oxide electrolysis cell 10. This reduces the amount of moisture in the product gas 10a.

[0023] As described above, the reaction in the solid oxide electrolysis cell 10 is an endothermic reaction, and it is preferable to preheat the raw material gas 2 and raw material vapor 3 before introducing them into the solid oxide electrolysis cell 10. On the other hand, the reaction in the downstream reactor 11 is an exothermic reaction, and it is preferable to cool the product gas 10a before introducing it into the downstream reactor 11.

[0024] In the synthetic fuel production system 1 of the present embodiment, the first condenser 12 condenses the product gas 10a from the solid oxide electrolysis cell 10 through heat exchange with the feed gas 2 and feed steam 3 supplied to the solid oxide electrolysis cell 10. This allows the heat of the product gas 10a to be used to preheat the feed gas 2 and feed steam 3, improving the energy efficiency of the entire system compared to when the heat of the product gas 10a is released into the atmosphere.

[0025] The synthetic fuel production system 1 may further include a feed gas source 20 that supplies a feed gas 2 and a feed steam source 30 that supplies a feed steam 3. The solid oxide electrolysis cell 10 may have a first inlet 101 into which the feed gas 2 and the feed steam 3 are introduced, and a first outlet 102 from which the product gas 10a is discharged. The first condenser 12 may be disposed between the feed gas source 20 and the feed steam source 30 and the first inlet 101 of the solid oxide electrolysis cell 10. The first condenser 12 may also be disposed between the first outlet 102 of the solid oxide electrolysis cell 10 and the feed steam source 30.

[0026] The raw material gas source 20 may be a tank or the like that stores the raw material gas 2. The raw material vapor supply source 30 may have any configuration, but the raw material vapor supply source 30 of this embodiment has a second condenser 15 and an evaporator 16, which will be described later.

[0027] Although the raw material gas 2 may be mixed with the raw material steam 3 before being introduced into the first condenser 12, the synthetic fuel production system 1 of this embodiment is configured so that the raw material gas 2 and the raw material steam 3 are introduced separately into the first condenser 12 and mixed after heat exchange with the produced gas 10a in the first condenser 12. This configuration can be realized by providing separate channels in the first condenser 12 for the raw material gas 2, the raw material steam 3, and the produced gas 10a. When the low-temperature raw material gas 2 is mixed with the raw material steam 3, the raw material steam 3 may condense, resulting in the generation of condensed water before being introduced into the first condenser 12. By mixing the raw material gas 2 and the raw material steam 3 after heat exchange with the produced gas 10a as in this embodiment, the condensation of the raw material steam 3 is suppressed, and the generation of condensed water before the raw material steam 3 is introduced into the first condenser 12 can be prevented. The temperature of the raw material gas 2 before being introduced into the first condenser 12 may be 25° C. or room temperature, and the temperature of the raw material vapor 3 before being introduced into the first condenser 12 may be 180° C. In other words, the raw material vapor 3 may be superheated steam.

[0028] A portion of the product gas 10a discharged from the first condenser 12 may be mixed with the feed gas 2 and returned to the first condenser 12. The amount of the product gas 10a returned to the first condenser 12 may be controlled based on the operating status or capacity of the downstream reactor 11.

[0029] A first blower 12 a (or compressor) may be provided between the first condenser 12 and the downstream reactor 11 to pump the generated gas 10 a from the first condenser 12 to the downstream reactor 11 .

[0030] The synthetic fuel production system 1 may further include a first heater 13 that heats the raw material gas 2 and raw material steam 3 at the outlet side of the first condenser 12 for the raw material gas 2 and raw material steam 3. The amount and temperature of the produced gas 10a may change depending on the operating status of the solid oxide electrolysis cell 10, which may change the temperatures of the raw material gas 2 and raw material steam 3 at the outlet side of the first condenser 12. Heating the raw material gas 2 and raw material steam 3 with the first heater 13 allows the raw material gas 2 and raw material steam 3 at stable temperatures to be supplied to the solid oxide electrolysis cell 10.

[0031] In this embodiment, the source gas 2 and the source vapor 3 are mixed before being introduced into the first heater 13. However, other configurations may be employed, such as, for example, the first heater 13 including a plurality of heaters, which separately heat the source gas 2 and the source vapor 3, and then mix the source gas 2 and the source vapor 3.

[0032] Any device or member may be used as the first heater 13. For example, a honeycomb structure having an outer peripheral wall and partition walls disposed inside the outer peripheral wall to define a plurality of cells forming flow paths extending from one end face to the other end face, and configured so that the raw material gas 2 and raw material steam 3 pass through the cells, may be used as the first heater 13. The raw material gas 2 and raw material steam 3 may be heated by heating the honeycomb structure by any method such as passing electricity through it.

[0033] The synthetic fuel production system 1 may further include a first heating control device 14 that detects the temperatures of the raw material gas 2 and raw material steam 3 at the outlet side of the first condenser 12 for the raw material gas 2 and raw material steam 3, and controls the amount of heating of the raw material gas 2 and raw material steam 3 by the first heater 13. By controlling the amount of heating in this manner by the first heating control device 14, the temperatures of the raw material gas 2 and raw material steam 3 can be more reliably set to target temperatures, and the raw material gas 2 and raw material steam 3 at more reliably stable temperatures can be supplied to the solid oxide electrolysis cell 10.

[0034] The first heating control device 14 may have a thermometer for detecting the temperatures of the raw material gas 2 and the raw material vapor 3 in a pipe connected to the outlet side of the first condenser 12 .

[0035] The synthetic fuel production system 1 may further include a second condenser 15, which is disposed on the inlet side of the first condenser 12 for the raw material steam 3 and condenses the synthetic fuel 4 from the downstream reactor 11 by heat exchange with raw material water 3a, which is the raw material of the raw material steam 3. As described above, the reaction for producing the synthetic fuel 4 may produce water (HO), and this water may be mixed with the synthetic fuel 4. By condensing the synthetic fuel 4, the moisture content in the synthetic fuel 4 can be reduced. Furthermore, by using the heat of the synthetic fuel 4 to heat the raw material water 3a, the energy efficiency of the entire system can be improved compared to when the heat of the synthetic fuel 4 is released into the atmosphere.

[0036] The second condenser 15 may be disposed between the tank 40 for storing the synthetic fuel 4 and the post-stage reactor 11 in terms of the flow direction of the synthetic fuel 4. The synthetic fuel 4 from the post-stage reactor 11 has a temperature of about 300°C, and the synthetic fuel 4 may be cooled to about 25°C by heat exchange in the second condenser 15.

[0037] The temperature of the raw water 3a in the second condenser 15 is preferably less than 100°C. In other words, it is preferable not to boil the raw water 3a in the second condenser 15. When a constant amount of raw water 3a is supplied to the second condenser 15, the amount of synthetic fuel 4 produced in the subsequent reactor 11 can be adjusted by adjusting the amount of feed gas 2 supplied to the solid oxide electrolysis cell 10. By reducing the amount of synthetic fuel 4 produced, the amount of temperature rise of the raw water 3a in the second condenser 15 can be reduced, and the temperature of the raw water 3a in the second condenser 15 can be kept less than 100°C.

[0038] A pump 15a for supplying raw water 3a may be provided upstream of the second condenser 15 in the flow direction of the raw water 3a or raw steam 3.

[0039] The synthetic fuel production system 1 may further include an evaporator 16. The evaporator 16 includes a second heater 16a and is disposed on the inlet side of the first condenser 12 for the raw material steam 3. The evaporator 16 may generate the raw material steam 3 by evaporating raw water 3a, which is the raw material for the raw material steam 3, using the heat generated by the downstream reactor 11 and the heating of the second heater 16a. As described above, the reaction for producing the synthetic fuel 4 is an exothermic reaction, and it may be necessary to cool the downstream reactor 11. By removing the heat generated by the downstream reactor 11 from the downstream reactor 11 and using that heat to generate the raw material steam 3, the energy efficiency of the entire system can be improved compared to when the heat generated by the downstream reactor 11 is released into the atmosphere. However, the amount of heat generated by the downstream reactor 11 may vary depending on the operating status of the downstream reactor 11. By using the second heater 16a, the raw material steam 3 can be generated more reliably.

[0040] A heat transfer medium 16b may be circulated between the downstream reactor 11 and the evaporator 16. The heat transfer medium 16b that absorbs the heat generated by the downstream reactor 11 may exchange heat with the raw water 3a. Any material may be used as the heat transfer medium 16b, and for example, a liquid such as water or oil may be used. Any material may be used as the second heater 16a, and a honeycomb structure may be used as with the first heater 13 described above. The evaporator 16 may be arranged downstream of the second condenser 15 or upstream of the first condenser 12 with respect to the flow direction of the raw water 3a or raw steam 3.

[0041] The synthetic fuel production system 1 may further include a second heating control device 17 that detects the heat generated by the downstream reactor 11 and / or the amount of raw material steam 3 generated at the outlet of the evaporator 16 related to the raw material steam 3, and controls the amount of heating of the raw water 3a by the second heater 16a. By controlling the amount of heating in this manner with the second heating control device 17, the raw material steam 3 can be produced more reliably regardless of the operating status of the downstream reactor 11.

[0042] The second heating control device 17 may have a thermometer that detects the temperature of the heat transfer medium 16b flowing from the downstream reactor 11 to the evaporator 16, and the temperature of the heat transfer medium 16b may be used as the heat generated in the downstream reactor 11. The second heating control device 17 may also have a thermometer, a flow meter, and a pressure gauge that detect the amount of raw material vapor 3 generated at the outlet side of the evaporator 16 related to the raw material vapor 3.

[0043] The synthetic fuel production system 1 may further include a heat exchanger 18 that exchanges heat between the mixed gas of oxygen and the sweep gas discharged from the solid oxide electrolysis cell 10 and the sweep gas introduced into the solid oxide electrolysis cell 10. Such heat exchange by the heat exchanger 18 can improve thermal efficiency.

[0044] The mixed gas of oxygen and the sweep gas may be discharged after heat exchange with the sweep gas in the heat exchanger 18. The temperature of the mixed gas of oxygen and the sweep gas introduced from the solid oxide electrolysis cell 10 to the heat exchanger 18 may be about 800°C, but the temperature of the mixed gas of oxygen and the sweep gas at the time of being discharged may be about 300°C. A third blower 18a that pressure-feeds the sweep gas introduced into the solid oxide electrolysis cell 10 toward the heat exchanger 18 may be connected to the heat exchanger 18.

[0045] The synthetic fuel production system 1 may further include a third heater 19 that heats the sweep gas introduced into the solid oxide electrolysis cell 10. The third heater 19 heats the sweep gas, thereby raising the temperature of the solid oxide electrolysis cell 10 at startup. Any heater may be used as the third heater 19, and a honeycomb structure may be used as the first heater 13 described above.

[0046] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0047] 1: Synthetic fuel production system 2: Feed gas 3: Feed steam 3a: Feed water 4: Synthetic fuel 10: Solid oxide electrolysis cell 10a: Produced gas 11: Post-stage reactor 12: First condenser 13: First heater 14: First heating control device 15: Second condenser 16: Evaporator 16a: Second heater 17: Second heating control device

Claims

1. A synthetic fuel production system comprising: a solid oxide electrolysis cell to which a feed gas and a feed steam are supplied; a post-reactor that produces a synthetic fuel from the product gas of the solid oxide electrolysis cell; and a first condenser that condenses the product gas of the solid oxide electrolysis cell by heat exchange with the feed gas and the feed steam supplied to the solid oxide electrolysis cell.

2. The synthetic fuel production system according to claim 1, further comprising: a first heater for heating the raw material gas and the raw material steam at the outlet side of the first condenser for the raw material gas and the raw material steam.

3. The synthetic fuel production system according to claim 2, further comprising a first heating control device that detects the temperatures of the raw material gas and the raw material steam at the outlet side of the first condenser for the raw material gas and the raw material steam, and controls the amount of heating of the raw material gas and the raw material steam by the first heater.

4. The synthetic fuel production system according to claim 1, further comprising a second condenser disposed on the inlet side of the first condenser for the raw material steam, and condensing the synthetic fuel from the subsequent reactor by heat exchange with raw water, which is the raw material for the raw material steam.

5. A synthetic fuel production system as claimed in any one of claims 1 to 4, further comprising an evaporator having a second heater, arranged on the inlet side of the first condenser for the raw material steam, and evaporating raw material water, which is the raw material for the raw material steam, using the heat generated by the post-stage reactor and the heating of the second heater to generate the raw material steam.

6. The synthetic fuel production system according to claim 5, further comprising a second heating control device that detects the heat generated by the downstream reactor and / or the amount of raw material steam generated at the outlet side of the evaporator related to the raw material steam, and controls the amount of heating of the raw material water by the second heater.

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