Manufacturing system for synthetic compounds

Abstract

This invention provides a synthetic compound manufacturing system that can maintain the water, which has been sent to a reactor to recover reaction heat, in a liquid phase and supply it to a water electrolysis cell stack for circulation. [Solution] The synthetic compound manufacturing system 10 comprises a water electrolysis cell stack 20, a reactor 30 that produces a synthetic compound and water using carbon dioxide and hydrogen produced in the water electrolysis cell stack 20 as raw materials, a water circulation heat medium passage that sends water discharged from the water electrolysis cell stack 20 to the reactor 30 to recover reaction heat, and supplies the water after the reaction heat has been recovered to the water electrolysis cell stack 20, circulating the water that will be used as raw material for water electrolysis in the water electrolysis cell stack 20 between the reactor 30 and the water electrolysis cell stack 20, and a back pressure valve 44 that maintains the water in the water circulation heat medium passage at a pressure that maintains a liquid phase state in the reactor 30.

Description

Technical Field

[0001] The present invention relates to a synthetic compound production system that generates a synthetic compound using hydrogen from a water electrolysis cell stack that electrolyzes water to generate hydrogen and oxygen.

Background Art

[0002] Conventionally, a synthetic compound production system that generates synthetic compounds such as methane using hydrogen has been proposed. For example, a synthetic compound production system has been proposed in which hydrogen generated by a water electrolysis device is supplied to a reactor for synthetic compounds together with carbon dioxide to generate synthetic compounds (see Patent Document 1).

[0003] In order to effectively utilize the reaction heat obtained in the reactor, the raw material water of the water electrolysis device is heated. In Patent Document 1, raw material water is supplied to the cooling layer (heat exchanger) of the reactor to generate water vapor, and the water vapor is supplied to the water electrolysis device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, the reaction heat of the reactor is at a high temperature, and water vapor is generated in Patent Document 1. When supplying and circulating liquid-phase water to the water electrolysis device, it is difficult to directly perform heat exchange with the reaction heat of the reactor.

Summary of the Invention

[0007] A synthetic compound manufacturing system according to the first embodiment comprises: a water electrolysis cell stack; a reactor that produces a synthetic compound and water using carbon dioxide and hydrogen produced in the water electrolysis cell stack as raw materials; a water circulation heat medium passage that sends water discharged from the water electrolysis cell stack to the reactor to recover the reaction heat, and supplies the water after the reaction heat has been recovered to the water electrolysis cell stack, and circulates the water that will be used as a raw material for water electrolysis in the water electrolysis cell stack between the reactor and the water electrolysis cell stack; and a pressure maintaining unit that maintains the water in the water circulation heat medium passage at a pressure that maintains a liquid phase state in the reactor.

[0008] In the first embodiment of the synthetic compound manufacturing system, the water in the water circulation heat transfer fluid path is maintained at a pressure that keeps it in the liquid phase within the reactor by a pressure maintenance unit. Therefore, the water that has been sent to the reactor to recover the reaction heat can be circulated while maintaining its liquid phase.

[0009] A synthetic compound manufacturing system according to a second embodiment is a synthetic compound manufacturing system according to a first embodiment, comprising: an external water supply channel that supplies water from the outside by joining with the upstream side of the reactor in the water circulation heat medium channel; and a pressurizer provided in the external water supply channel that increases the pressure of the external water to a pressure equal to or greater than that maintained by the pressure maintenance unit.

[0010] According to the synthetic compound manufacturing system of the second embodiment, by increasing the pressure of external water to a level higher than that maintained by the pressure maintenance unit, the supply of water to the water circulation heat transfer medium can be made smoother.

[0011] A third embodiment of the synthetic compound manufacturing system is a synthetic compound manufacturing system of the second embodiment, further comprising a bypass channel that branches off from the external water supply channel and bypasses the high-pressure water, which has been pressurized by the booster, from the upstream side to the downstream side of the reactor.

[0012] According to the third embodiment of the synthetic compound production system, the amount of reaction heat recovered in the reactor can be adjusted by bypassing water into the bypass channel.

[0013] A synthetic compound manufacturing system according to a fourth embodiment is a synthetic compound manufacturing system according to a third embodiment, comprising: a temperature sensing unit provided downstream of the reactor and upstream of the water electrolysis cell stack in the water circulation heat transfer medium path; and a flow rate adjustment unit that adjusts the flow rate of water bypassed to the bypass flow path based on the temperature detected by the temperature sensing unit.

[0014] According to the synthetic compound manufacturing system of the fourth embodiment, the temperature of the water supplied to the water electrolysis cell stack can be adjusted to a desired temperature by adjusting the amount of water bypassed to the bypass channel in the flow rate adjustment unit based on the temperature detected by the temperature sensing unit.

[0015] The fifth embodiment of the synthetic compound production system is a synthetic compound production system according to any one embodiment of the first to fourth embodiments, wherein an ion exchange resin is provided downstream of the reactor in the water circulation heat transfer medium and upstream of the water electrolysis cell stack.

[0016] According to the synthetic compound production system of the fifth embodiment, impurities can be efficiently removed from the circulating water that has passed through the reactor. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a synthetic compound manufacturing system that maintains water in the liquid phase, after it has been sent to a reactor to recover the reaction heat, and supplies it to a water electrolysis cell stack for circulation. [Brief explanation of the drawing]

[0018] [Figure 1] This is a block diagram schematically showing the configuration of the synthetic compound manufacturing system according to this embodiment. [Figure 2] This diagram shows the connection between the synthetic compound manufacturing system and the control unit according to this embodiment. [Modes for carrying out the invention]

[0019] Hereinafter, embodiments for carrying out the present invention will be described based on the drawings.

[0020] FIG. 1 shows a synthetic compound production system 10. The synthetic compound production system 10 includes a water electrolysis cell stack 20, a water separation unit 22, an ion exchange resin 24, a compressor 40, a reactor 30, and a cation exchange resin 26.

[0021] The water electrolysis cell stack 20 is formed by stacking water electrolysis cells that form an anode and a cathode with an electrolyte membrane interposed therebetween. In the present embodiment, an example using a PEM type (Proton Exchange Membrane) as the water electrolysis cell stack 20 will be described. In the water electrolysis cell stack 20, by energization, the water supplied to the anode is electrolyzed as shown in formula (1), oxygen is generated at the anode, and hydrogen is generated at the cathode. In the present embodiment, as an example, a water electrolysis cell stack 20 with an operating suitable temperature of normal temperature to 150°C can be used. The water electrolysis cell stack 20 is connected to a control unit 50 via a DC power supply device DC (see FIG. 2), and the energization amount is controlled by the control unit 50, and the water electrolysis amount is controlled.

[0022] H2O → H2 + (1 / 2)O2 (1)

[0023] One end of a third water circulation heat medium path 14C described later is connected to the anode side inlet of the water electrolysis cell stack 20, and water is supplied from the third water circulation heat medium path 14C to the anode of the water electrolysis cell stack 20. A hydrogen delivery path 12 is connected to the cathode side outlet of the water electrolysis cell stack 20. A water separation unit 21 is provided in the hydrogen delivery path 12. The water separation unit 21 has a gas-liquid separation function and separates hydrogen (gas) and water (liquid) from the hydrogen delivery path 12.

[0024] One end of the water return channel 11 is connected to the water separation section 21. The water return channel 11 discharges the separated water. The other end of the water return channel 11 is connected to the external water supply channel 16, which will be described later, downstream of the ion exchange resin 24 and upstream of the compressor 40. The water separated in the water separation section 21 is joined to the external water supply channel 16, and the hydrogen is sent to the reactor 30, which will be described later.

[0025] One end of the water-oxygen delivery passage 15 is connected to the anode outlet of the water electrolysis cell stack 20, and oxygen and water are delivered from the water-oxygen delivery passage 15. The other end of the water-oxygen delivery passage 15 is connected to the water separation unit 22.

[0026] The water separation unit 22 has a gas-liquid separation function and separates oxygen (gas) and water (liquid) from the water-oxygen delivery passage 15. One end of the first water circulation heat medium passage 14A is connected to the water separation unit 22. The first water circulation heat medium passage 14A delivers the separated water. The other end of the first water circulation heat medium passage 14A is connected to the heat exchange section 34 of the reactor 30, which will be described later.

[0027] Furthermore, an oxygen outlet passage 13 is connected to the water separation section 22, and oxygen is supplied from the oxygen outlet passage 13. A back pressure valve 44 is provided in the oxygen outlet passage 13. The back pressure valve 44 is set so that the oxygen pressure upstream of the back pressure valve 44 in the oxygen outlet passage 13 becomes a predetermined anode pressure P1. Here, the anode pressure P1 corresponds to the water pressure in the first water circulation heat medium passage 14A, and is a high pressure sufficient to maintain the liquid phase state of water even after the reaction heat of the reaction section 32 has been recovered. For example, if the temperature of the reaction section 32 is maintained at about 300°C and the temperature of the high-pressure water after heat exchange is about 180°C, the anode pressure P1 will be about 1.2 MPa to 1.6 MPa.

[0028] An external water supply channel 16 is connected to the first water circulation heat transfer medium channel 14A, which receives tap water. The external water supply channel 16 is equipped with an ion exchange resin 24 and a compressor 40, in order from the upstream side. The ion exchange resin 24 removes impurities contained in the water by ion exchange treatment and maintains the electrical resistivity at a value close to that of theoretically pure water. As the ion exchange resin 24, for example, a mixed bed of a strongly acidic cationic resin and a strongly basic anionic resin, for example, SO3 - X + A strongly acidic cation exchange resin having a functional group, and N + (CH3)3·X - The mixed resin and resin matrix of the anion exchange resin having functional groups can be made of a general styrene-based material. In addition to the ion exchange resin, filters, membranes, devices, etc., that remove physical debris and chlorine may be attached.

[0029] The compressor 40 pressurizes the water that has passed through the ion exchange resin 24. The pressurized water is then combined with the water from the water separation unit 22 in the first water circulation heat medium path 14A at the confluence G, and sent to the heat exchange unit 34 of the reactor 30, which will be described later.

[0030] The reactor 30 is equipped with a reaction section 32 and a heat exchange section 34. The reaction section 32 is connected to a hydrogen outlet passage 12 and a carbon dioxide supply passage 17. Hydrogen produced by water electrolysis in the water electrolysis cell stack 20 is supplied from the hydrogen outlet passage 12, and carbon dioxide is supplied from the carbon dioxide supply passage 17.

[0031] Within the reaction section 32, as an example, methane and water are produced by a methane synthesis reaction as shown in equation (2) below. The produced gas (product gas) is discharged from the product gas passage 19.

[0032] 4H2 + CO2 → CH4 + 2H2O (2)

[0033] The heat exchange section 34 is located in a position within the reactor 30 to recover the reaction heat from the reaction section 32 and to cool the reaction section 32. The first water circulation heat medium passage 14A is connected to the inlet side of the heat exchange section 34, and the second water circulation heat medium passage 14B is connected to the outlet side of the heat exchange section 34. The water separated in the water separation section 22 and the pressurized high-pressure water from the external water supply passage 16 merge at the confluence section G and are sent from the first water circulation heat medium passage 14A to the heat exchange section 34. In the compressor 40, the external supply water is pressurized at the confluence section G to a degree that allows the water from the first water circulation heat medium passage 14A and the water supplied from the external water supply passage 16 to merge smoothly. Specifically, the water pressure is increased to a level equal to or greater than the water pressure in the first water circulation heat medium passage 14A. In the heat exchange section 34, high-pressure water recovers the reaction heat in the reaction section 32 and is sent to the second water circulation heat medium passage 14B.

[0034] A temperature sensor 38 is provided in the second water circulation heat transfer medium circuit 14B. The temperature sensor 38 detects the temperature T1 of the high-pressure water sent to the cation exchange resin 26. The temperature sensor 38 is connected to the control unit 50 and outputs the detected temperature T1 to the control unit 50.

[0035] Here, the water pressure in the compressor 40 is set to approximately the same as the anode pressure P1, or slightly higher than the anode pressure P1, in order to combine it with the water in the first water circulation heat transfer medium 14A, which is maintained at the anode pressure P1.

[0036] The water sent to the second water circulation heat transfer fluid path 14B is supplied to the water electrolysis cell stack 20 via the cation exchange resin 26, along with the high-pressure water bypassed in the bypass channel 18 (described later). The cation exchange resin 26 is made of a material with a higher heat resistance temperature than the ion exchange resin 24. The cation exchange resin 26 also performs ion exchange treatment on the water to remove impurities contained in the water and maintains the electrical resistivity at a value close to that of theoretically pure water. For example, SO3 - X + A strongly acidic cation exchange resin having functional groups can be used.

[0037] The flow path from the cation exchange resin 26 to the water electrolysis cell stack 20 is referred to as the third water circulation heat medium path 14C. The water circulation heat medium path is composed of the water oxygen delivery path 15, the first water circulation heat medium path 14A, the second water circulation heat medium path 14B, and the third water circulation heat medium path 14C.

[0038] A bypass channel 18 is formed between the external water supply channel 16 downstream of the compressor 40 and the second water circulation heat medium channel 14B upstream of the temperature sensor 38. A flow control valve 42 is provided in the bypass channel 18. The flow control valve 42 can adjust the flow rate of high-pressure water supplied to the reactor 30 and high-pressure water that is mixed with high-pressure water sent from the reactor 30 without passing through the reactor 30. The flow control valve 42 is connected to the control unit 50, and its opening is adjusted so that the temperature T1 becomes the optimal temperature T0 for the cation exchange resin. The optimal temperature T0 for the cation exchange resin is set as the temperature at which the cation exchange resin 26 functions efficiently (a temperature at which ion exchange can be promoted), and is set within a range of 150°C or less. The flow control valve 42 receives feedback from the control unit 50 regarding the temperature T1. When the temperature T1 is higher than the optimal temperature T0 for the cation exchange resin, the valve opens wider to increase the flow rate to the bypass channel 18. When the temperature T1 is lower than the optimal temperature T0 for the cation exchange resin, the valve opens narrower to decrease the flow rate to the bypass channel 18.

[0039] As shown in Figure 2, the control unit 50 is connected to a DC power supply unit DC, a temperature sensor 38, and a flow control valve 42. The control unit 50 is also connected to the water electrolysis cell stack 20 via the DC power supply unit DC. The control unit 50 includes a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, an input / output interface (I / O) 54, and a storage unit 55.

[0040] The CPU 51, ROM 52, RAM 53, and I / O 54 are connected to each other via the bus 56. Each functional unit, including the memory unit 55, is connected to the I / O 54. These functional units are able to communicate with the CPU 51 via the I / O 54.

[0041] For the storage unit 55, for example, an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory may be used. The storage unit 55 stores control programs for controlling each part of the synthetic compound manufacturing system 10, as well as various data (for example, the optimal temperature T0 of the cation exchange resin). Note that these control programs and various data may also be stored in the ROM 52.

[0042] In the synthetic compound manufacturing system 10 of this embodiment, water supplied as a raw material to the water electrolysis cell stack 20 is supplied directly to the reactor 30 to recover the reaction heat. Therefore, there is no need to provide a separate heat transfer fluid channel using heat transfer oil or the like, or a heat exchanger outside the reactor 30, in order to recover the reaction heat from the reactor 30, and the reaction heat can be easily recovered to heat the water.

[0043] Furthermore, the back pressure valve 44 sets the oxygen pressure upstream of the back pressure valve 44 in the oxygen delivery passage 13 to the anode pressure P1, thereby maintaining the water pressure in the first water circulation heat medium passage 14A at a high pressure (high enough to maintain the liquid phase state of water even after the reaction heat from the reaction section 32 has been recovered). This allows the water from which the reaction heat has been recovered in the heat exchange section 34 to be circulated while remaining in the liquid phase.

[0044] As in this embodiment, by providing the compressor 40 in the external water supply passage 16, it can also serve as a drive source for supplying external water, enabling efficient supply of external water.

[0045] Furthermore, in this embodiment, by providing a bypass channel 18 and adjusting the bypass flow rate with the flow control valve 42, the temperature of the water sent to the cation exchange resin 26 can be brought closer to the optimal temperature T0 for the cation exchange resin.

[0046] In this embodiment, a cation exchange resin 26 made of a material with a higher heat resistance temperature than the ion exchange resin 24 is provided in the second water circulation heat medium passage 14B. However, a material similar to the ion exchange resin 24 or other ion exchange resins can be used. In this embodiment, since a cation exchange resin 26 with a high heat resistance temperature is used, the incoming water temperature can be set higher, bringing it closer to the optimal operating temperature of the water electrolysis cell stack 20.

[0047] Furthermore, in this embodiment, a PEM type was used as the water electrolysis cell stack 20, but in other embodiments, an AEM type (Anion Exchange Membrane) can also be used. In this case, the raw material water is supplied to the cathode side of the water electrolysis cell stack 20. [Explanation of Symbols]

[0048] 10. Manufacturing System for Synthetic Compounds 12 Hydrogen delivery path 13 Oxygen delivery path 14A 1st water circulation heat transfer path (water circulation heat transfer path) 14B 2nd water circulation heat transfer path (water circulation heat transfer path) 14C 3rd water circulation heat transfer path (water circulation heat transfer path) 15 Water oxygen delivery path (water circulation heat transfer path) 16 External water supply channel 18 Bypass channel 20 Water Electrolysis Cell Stacks 24 Ion exchange resin 26. Cation exchange resin (ion exchange resin) 30 Reactors 40 Compressor (Voltage Booster) 42 Flow control valve (flow control section) 44. Back pressure valve (pressure maintenance unit) 50 Control Unit (Flow Rate Adjustment Unit)

Claims

1. Water electrolysis cell stack, A reactor that produces synthetic compounds and water using carbon dioxide and hydrogen generated in the water electrolysis cell stack as raw materials, A water circulation heat medium is provided to circulate water between the reactor and the water electrolysis cell stack, where the water discharged from the water electrolysis cell stack is sent to the reactor to recover the reaction heat, the water after the reaction heat has been recovered is supplied to the anode side of the water electrolysis cell stack, and water is sent out from the anode side, and the water that will be used as the raw material for water electrolysis in the water electrolysis cell stack is circulated between the reactor and the water electrolysis cell stack. A pressure maintenance unit controls the pressure upstream of the reactor in the water circulation heat transfer medium and downstream of the water electrolysis cell stack, maintaining the water in the water circulation heat transfer medium at a pressure that maintains a liquid phase state within the reactor. A synthetic compound manufacturing system equipped with the following features.

2. An external water supply channel that supplies water from the outside by joining with the upstream side of the reactor in the water circulation heat transfer medium channel, A pressure booster is provided in the external water supply channel and increases the pressure of the external water to a level greater than or equal to the pressure maintained by the pressure maintenance unit. Equipped with, A synthetic compound production system according to claim 1.

3. A bypass channel is branched from the external water supply channel and bypasses the high-pressure water, which has been pressurized by the booster, from the upstream side to the downstream side of the reactor. A synthetic compound production system according to claim 2, comprising:

4. A temperature sensing unit is provided on the downstream side of the reactor in the water circulation heat medium path, on the upstream side of the water electrolysis cell stack, and downstream of the confluence of the bypass flow path and the water circulation heat medium path downstream of the reactor. A flow rate adjustment unit adjusts the flow rate of water bypassed to the bypass channel based on the temperature detected by the temperature detection unit, A synthetic compound production system according to claim 3, comprising the above.

5. The water circulation heat transfer medium is provided with an ion exchange resin on the downstream side of the reactor and the upstream side of the water electrolysis cell stack. A synthetic compound production system according to any one of claims 1 to 4.

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