Chemical Reaction System

Abstract

To provide a chemical reaction system capable of supplying a gas for a reaction to a reactor at a suitable pressure and flow rate for the reaction.SOLUTION: A chemical reaction system 1 comprises: a compressor 31 for compressing a gas; a flow rate adjusting part 33 for adjusting a flow rate of the gas compressed by the compressor 31; a return channel 34 for returning the gas compressed by the compressor 31 to a suction hole of the compressor 31; a pressure adjusting part 35 provided on the return channel 34, and adjusting the pressure of the gas compressed by the compressor 31; and a reactor 37 for generating a product of reaction from the gas whose flow rate is adjusted by the flow rate adjusting part 33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to chemical reaction systems. [Background technology]

[0002] Carbon dioxide is considered a problem as a cause of global warming, and there has been a worldwide movement to curb carbon dioxide emissions.Methanation technology, which produces methane from carbon dioxide in exhaust gases, is known as a method for reducing carbon dioxide emissions into the atmosphere and effectively utilizing carbon dioxide.

[0003] Patent Document 1 discloses a methane production apparatus that produces methane from carbon dioxide and hydrogen. The methane production apparatus includes a first reactor that causes a methanation reaction, a second reactor that is disposed downstream of the first reactor and also causes a methanation reaction, and a pressure booster that boosts the pressure of the reaction mixture gas supplied to the second reactor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-142807 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in methanation reactions and Fischer-Tropsch reactions (FT reactions), the higher the pressure, the higher the yield of the reaction product. Therefore, by supplying gas compressed by a compressor to the reactor, the yield of the reaction product can be increased. However, it is not easy for a compressor to flow gas at a low flow rate at high pressure, and if gas compressed by a compressor is directly supplied to the reactor, there is a risk that the pressure and flow rate within the reaction may not be maintained appropriately.

[0006] Therefore, an object of the present disclosure is to provide a chemical reaction system that can supply a gas used in a reaction to a reactor at a pressure and flow rate suitable for the reaction. [Means for solving the problem]

[0007] The chemical reaction system according to the present disclosure includes a compressor that compresses gas, a flow rate regulator that regulates the flow rate of the gas compressed by the compressor, and a return flow path that returns the gas compressed by the compressor to an inlet of the compressor. The chemical reaction system also includes a pressure regulator that is provided in the return flow path and regulates the pressure of the gas compressed by the compressor, and a reactor that produces a reaction product from the gas whose flow rate has been regulated by the flow rate regulator.

[0008] The chemical reaction system may further include a tank that absorbs pressure fluctuations of the gas compressed by the compressor.

[0009] The gas may include carbon dioxide.

[0010] The chemical reaction system may include a carbon dioxide capture device that captures carbon dioxide by chemical absorption, and the gas compressed by the compressor may contain carbon dioxide released from the carbon dioxide capture device.

[0011] The chemical reaction system may include a hydrogen supply that provides hydrogen to the reactor.

[0012] The reaction products may include hydrocarbons. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a chemical reaction system capable of supplying a gas used in a reaction to a reactor at a pressure and flow rate suitable for the reaction. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating a chemical reaction system according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, several exemplary embodiments will be described with reference to the drawings. Note that the dimensional proportions of the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0016] As shown in FIG. 1, the chemical reaction system 1 according to this embodiment includes a carbon dioxide generation source 10, a carbon dioxide recovery device 20, a compressor 31, a tank 32, a flow rate control unit 33, a return flow path 34, a pressure control unit 35, a hydrogen supply unit 36, and a reactor 37.

[0017] The carbon dioxide generation source 10 is, for example, a power plant or factory that emits carbon dioxide by burning fuel, etc. The carbon dioxide generation source 10 may include a boiler.

[0018] The carbon dioxide capture device 20 captures the carbon dioxide generated from the carbon dioxide generation source 10. By capturing the carbon dioxide generated from the carbon dioxide generation source 10, the carbon dioxide capture device 20 can reduce the amount of carbon dioxide released into the atmosphere.

[0019] The carbon dioxide capture unit 20 may capture carbon dioxide by a chemical absorption method. As shown in Fig. 1 , the carbon dioxide capture unit 20 may include an absorption tower 21, a stripper tower 22, a supply pipe 23, a reflux pipe 24, a heat exchanger 25, a cooler 27, and a gas-liquid separator 28. The supply pipe 23 connects the lower part of the absorption tower 21 to the upper part of the stripper tower 22. The reflux pipe 24 connects the lower part of the stripper tower 22 to the upper part of the absorption tower 21. The supply pipe 23 and the reflux pipe 24 are provided with a heat exchanger 25.

[0020] The absorption tower 21 absorbs carbon dioxide through gas-liquid contact between a carbon dioxide-containing gas and an absorbing liquid. The stripper tower 22 strips the carbon dioxide absorbed in the absorption tower 21. The absorbing liquid may be an alkaline solution. Specifically, the absorbing liquid may contain at least one of an alkanolamine and a hindered amine having an alcoholic hydroxyl group. More specifically, the absorbing liquid may contain monoethanolamine (MEA).

[0021] The gas containing carbon dioxide supplied from the bottom of the absorption tower 21 comes into gas-liquid contact with the absorbing liquid, and the carbon dioxide contained in the gas is absorbed by the absorbing liquid. The absorbing liquid that has absorbed the carbon dioxide passes through the supply pipe 23, is heated by the heat exchanger 25, and is then sent to the top of the stripper tower 22. The absorbing liquid heated by the heat exchanger 25 drips down from the top of the stripper tower 22 while stripping carbon dioxide, and accumulates at the bottom of the stripper tower 22. The absorbing liquid that accumulates at the bottom of the stripper tower 22 is heated by a reboiler (not shown), and the carbon dioxide is stripped from the absorbing liquid. The stripped gas containing carbon dioxide is discharged from a gas outlet provided at the top of the stripper tower 22.

[0022] Meanwhile, the absorption liquid remaining at the bottom of the stripper tower 22 is cooled in a heat exchanger 25 through a reflux pipe 24 and then sent to the top of the absorption tower 21. At this time, heat is exchanged between the absorption liquid passing through the supply pipe 23 and the absorption liquid passing through the reflux pipe 24, so that the absorption liquid passing through the supply pipe 23 is heated and the absorption liquid passing through the reflux pipe 24 is cooled. The absorption liquid supplied from above the packing material of the absorption tower 21 comes into gas-liquid contact with the gas containing carbon dioxide supplied from the carbon dioxide generation source 10, and the carbon dioxide is again absorbed by the absorption liquid. The gas from which carbon dioxide has been removed in the absorption tower 21 is discharged from a gas outlet provided at the zenith of the absorption tower 21.

[0023] A pipe 26 is connected to the gas outlet of the stripper tower 22. The pipe 26 is provided with a cooler 27, a gas-liquid separator 28, a flow rate regulator 30, a compressor 31, a tank 32, a flow rate regulator 33, and a reactor 37. The gas stripped from the stripper tower 22 is cooled by the cooler 27, and the gas containing carbon dioxide is separated by the gas-liquid separator 28. The gas separated from the carbon dioxide capture device 20 contains, for example, 90% or more, 95% or more, or 99% or more by mass of carbon dioxide.

[0024] The flow rate adjuster 30 is provided in the pipe 26 downstream of the carbon dioxide capture device 20. The flow rate adjuster 30 adjusts the flow rate of the gas flowing through the pipe 26 in accordance with the pressure inside the stripper tower 22. The pressure inside the stripper tower 22 is set to be lower than the pressure inside the absorption tower 21 in order to promote the stripping of carbon dioxide. The pressure inside the stripper tower 22 may be, for example, 0.1 MPaG to 0.2 MPaG, depending on the type of absorption liquid.

[0025] In this embodiment, the carbon dioxide capture device 20 uses a chemical absorption method. However, the carbon dioxide capture device 20 may capture carbon dioxide using, for example, a pressure swing adsorption method, a temperature swing adsorption method, a membrane separation concentration method, or a combination of these methods.

[0026] The compressor 31 compresses gas. The gas compressed by the compressor 31 contains carbon dioxide. Specifically, the gas compressed by the compressor 31 contains carbon dioxide emitted from the carbon dioxide capture device 20. The compressor 31 has an inlet and a discharge port, and the gas sucked in through the inlet is compressed and discharged from the discharge port.

[0027] The compressor 31 may be a scroll compressor or a reciprocating compressor. These compressors can compress the gas to the pressure required for the reactor 37 and reduce the discharge flow rate. Therefore, carbon dioxide at a pressure and flow rate suitable for the reaction can be easily supplied to the reactor 37 by the return flow path 34 and pressure adjustment unit 35 described below.

[0028] The discharge pressure of the compressor 31 may be 0.3 MPaG or more and 3 MPaG or less. The discharge pressure may be 0.5 MPaG or more. Also, the discharge pressure may be 2 MPaG or less. The discharge flow rate of the compressor 31 may be, for example, 7 L / min to 50 L / min. The discharge flow rate may be 8 L / min or more. Also, the discharge flow rate may be 30 L / min or less, or 20 L / min or less.

[0029] As described above, since the pressure inside the stripper column 22 is reduced, it is preferable to set the pressure inside the reactor 37 to, for example, 0.3 MPaG or higher in order to efficiently proceed with the reaction in the reactor 37. However, if gas compressed by the compressor 31 is directly supplied to the reactor 37, an excessive amount of gas may be supplied to the reactor 37, and the target reaction may not be carried out efficiently. For example, it may be difficult to directly supply gas at a flow rate of 1 mL / min to 10 mL / min from the compressor 31 to the reactor 37 at the above-mentioned pressure. Therefore, in this embodiment, carbon dioxide is supplied to the reactor 37 using the tank 32, the flow rate adjustment unit 33, the return flow path 34, and the pressure adjustment unit 35.

[0030] The tank 32 absorbs pressure fluctuations of the gas compressed by the compressor 31. The tank 32 has a space for storing gas. The tank 32 is provided with a supply port for supplying the gas from the compressor 31 into the tank 32 and a discharge port for discharging the gas from the tank 32. The supply port and discharge port are open, and the compressor 31, the flow rate regulator 33, and the pressure regulator 35 are connected to each other. The capacity of the tank 32 may be 10 L or more and less than 40 L. If the capacity is 10 L or more, pressure fluctuations of the gas from the compressor 31 can be more effectively absorbed. Furthermore, if the capacity is less than 40 L, the time required to fill the tank 32 with gas can be reduced, allowing the chemical reaction system 1 to be started up quickly. Note that the chemical reaction system 1 does not necessarily have to include the tank 32. For example, the diameter of the pipe 26 may be expanded so that the pressure fluctuations of the gas compressed by the compressor 31 can be absorbed by the pipe 26.

[0031] The flow rate adjuster 33 adjusts the flow rate of the gas compressed by the compressor 31. The flow rate adjuster 33 can adjust the flow rate of the gas compressed by the compressor 31 and supplied to the reactor 37 so that the flow rate is less than the discharge flow rate of the compressor 31. As a result, even when a compressor 31 with a high discharge pressure is used and the discharge flow rate of the compressor 31 is high, the flow rate of the gas supplied to the reactor 37 becomes less than the discharge flow rate of the compressor 31. Therefore, an appropriate amount of gas can be supplied to the reactor 37. The flow rate adjuster 33 may include a mass flow controller.

[0032] The return flow path 34 returns the gas compressed by the compressor 31 to the suction port of the compressor 31. Specifically, the return flow path 34 returns the gas that is discharged from the tank 32 and has not yet been introduced into the flow rate adjuster 33 to the compressor 31. The return flow path 34 is connected to the upstream side and downstream side of the compressor 31 in the piping 26. Specifically, the return flow path 34 is connected to the piping 26 between the flow rate adjuster 30 and the compressor 31, and between the compressor 31 and the flow rate adjuster 33. In this embodiment, the return flow path 34 is connected to the piping 26 between the tank 32 and the flow rate adjuster 33, but may be connected between the compressor 31 and the tank 32.

[0033] The pressure adjustment unit 35 is provided in the return flow path 34 and adjusts the pressure of the gas compressed by the compressor 31. In this embodiment, the pressure is adjusted by the pressure adjustment unit 35, and the pressures at the discharge port of the compressor 31, the inlet of the flow rate adjustment unit 33, and the inlet of the pressure adjustment unit 35 are substantially the same. Therefore, the pressure adjustment unit 35 can adjust the pressure inside the tank 32. The pressure adjustment unit 35 may include a relief valve. By adjusting the pressure by the pressure adjustment unit 35, gas at an appropriate pressure can be supplied to the reactor 37. The pressure adjusted by the pressure adjustment unit 35 can be set appropriately depending on the pressure required in the reactor 37. The pressure may be, for example, 0.3 MPaG to 3 MPaG.

[0034] The hydrogen supply unit 36 ​​supplies hydrogen to the reactor 37. The hydrogen supply unit 36 ​​is not particularly limited as long as it can supply hydrogen to the reactor 37, but hydrogen obtained by electrolyzing water using renewable energy such as solar, wind, or hydraulic power may be used. By using such hydrogen, the chemical reaction system 1 as a whole can reduce carbon dioxide emissions.

[0035] The ratio of the amount of hydrogen to carbon dioxide supplied to reactor 37 can be set as appropriate, and may be, for example, a molar ratio of 1 or more, 2 or more, 3 or more, 3.5 or more, or 4 or more. The ratio of the amount of hydrogen to carbon dioxide supplied to reactor 37 may be, for example, a molar ratio of less than 8, less than 6, less than 5, or less than 4.5. In the case of a methanation reaction, the ratio of the amount of hydrogen to carbon dioxide supplied to reactor 37 may be 4, which is a stoichiometric ratio.

[0036] The reactor 37 produces a reaction product from the gas whose flow rate has been adjusted by the flow rate adjuster 33. Specifically, the reactor 37 produces a reaction product from a raw material containing the gas discharged from the tank 32. In this embodiment, the reactor 37 produces a reaction product from a raw material containing carbon dioxide.

[0037] The reaction product may contain hydrocarbons. Producing hydrocarbons in the reactor 37 not only reduces carbon dioxide emissions but also enables the effective utilization of carbon dioxide. The hydrocarbons may contain at least one of alkanes and alkenes. These hydrocarbons can be produced by a methanation reaction or a Fischer-Tropsch reaction. At least one of the alkanes and alkenes may contain hydrocarbons having 1 to 4 carbon atoms. Examples of alkanes having 1 to 4 carbon atoms include methane, ethane, propane, and butane. Examples of alkenes having 1 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, isobutene, and 1,3-butadiene. Among these, methane, ethane, and propane can be used as fuels for city gas. Furthermore, alkenes having 2 to 4 carbon atoms are useful as raw materials for plastics. The reaction product may also contain compounds other than those listed above.

[0038] The reactor 37 may be a known reactor, such as a multi-tubular reactor such as a shell-and-tube reactor, a fluidized-bed reactor, or a slurry-bed reactor. A catalyst is disposed in the reactor 37 through a channel through which the raw material passes, and hydrocarbons are produced by contacting the raw material with the catalyst. The catalyst is selected based on the type of hydrocarbons to be produced, and known catalysts such as iron catalysts or cobalt catalysts can be used. An iron catalyst can produce primarily light hydrocarbons, while a cobalt catalyst can produce primarily heavy hydrocarbons containing wax. Furthermore, an iron catalyst can produce primarily alkenes and alkanes, while a cobalt catalyst can produce primarily alkanes. The iron catalyst contains iron as an active component, and the cobalt catalyst contains cobalt as an active component. The reaction conditions in the reactor 37 are not particularly limited, but may be, for example, a reaction temperature of 200°C to 500°C and a pressure of 0.3 MPaG to 3 MPaG. The reaction product produced in the reactor 37 may be separated and purified using a separation and purification device (not shown).

[0039] An exhaust pipe 41 may be connected between the flow rate adjuster 30 and the compressor 31 in the pipe 26. A pressure adjuster 42 may be provided in the exhaust pipe 41. By adjusting the pressure with the pressure adjuster 42 and releasing the gas from the exhaust pipe 41, it is possible to prevent the pressure between the flow rate adjuster 30 and the compressor 31 in the pipe 26 from increasing. The set value of the pressure adjuster 42 may be, for example, 10 kPa or less.

[0040] Next, the operation of the chemical reaction system 1 according to this embodiment will be described. First, gas containing carbon dioxide emitted from the carbon dioxide capture device 20 is compressed by the compressor 31. The compressed gas is supplied to the tank 32. When the inlet pressure of the flow rate regulator 33 is less than the set pressure of the pressure regulator 35, the flow rate regulator 33 is closed so that gas is not supplied to the reactor 37. When the pressure inside the tank 32 exceeds the set pressure of the pressure regulator 35, the gas inside the tank 32 is returned to the suction port of the compressor 31 via the return flow path 34. The compressor 31 compresses a mixed gas containing the gas returned via the return flow path 34 and the carbon dioxide emitted from the carbon dioxide capture device 20.

[0041] After the pressure inside tank 32 reaches the set pressure of pressure adjustment unit 35, flow rate adjustment unit 33 is opened, and the flow rate of the gas supplied to reactor 37 is adjusted by flow rate adjustment unit 33. The pressure on the inlet side of flow rate adjustment unit 33 is adjusted to a predetermined pressure by pressure adjustment unit 35. Therefore, carbon dioxide gas whose flow rate has been adjusted by flow rate adjustment unit 33 is supplied to compressor 31 at an appropriate pressure, and the reaction proceeds.

[0042] The compressor 31 compresses a mixed gas containing gas returned via the return flow path 34 and carbon dioxide emitted from the carbon dioxide capture device 20. The pressure of the gas compressed by the compressor 31 is adjusted by the pressure adjustment unit 35, and the gas is continuously returned to the suction port of the compressor 31 via the return flow path 34. This allows the compressor 31 to be operated continuously, and allows gas to be stably supplied to the reactor 37 without intermittent operation of the compressor 31. Furthermore, gas can be stably supplied to the reactor 37 without connecting an inverter to the compressor 31.

[0043] As described above, the chemical reaction system 1 according to this embodiment includes a compressor 31 that compresses gas, a flow rate regulator 33 that regulates the flow rate of the gas compressed by the compressor 31, and a return flow path 34 that returns the gas compressed by the compressor 31 to the suction port of the compressor 31. The chemical reaction system 1 also includes a pressure regulator 35 that is provided in the return flow path 34 and regulates the pressure of the gas compressed by the compressor 31, and a reactor 37 that produces a reaction product from the gas whose flow rate has been regulated by the flow rate regulator 33.

[0044] In the chemical reaction system 1 according to this embodiment, a pressure adjusting unit 35 provided in the return flow path 34 is used, and the pressure-adjusted gas can be supplied to the reactor 37 with the flow rate adjusted by the flow rate adjusting unit 33. Therefore, according to the chemical reaction system 1 according to this embodiment, the gas used in the reaction can be supplied to the reactor 37 at a pressure and flow rate suitable for the reaction.

[0045] The chemical reaction system 1 according to this embodiment is suitable for use with a small reactor 37 because it can supply the gas used in the reaction to the reactor 37 at a pressure and flow rate suitable for the reaction. The chemical reaction system 1 can be used favorably, for example, when it is desired to experimentally produce a reaction product. Furthermore, when using hydrogen generated using renewable energy, the amount of hydrogen supplied may become rate-limiting due to reasons such as location. In such cases, using a small reactor 37 allows the reaction to proceed under optimal reaction conditions.

[0046] The chemical reaction system 1 may further include a tank 32 that absorbs pressure fluctuations of the gas compressed by the compressor 31. Such a tank 32 can suppress fluctuations in the flow of the gas supplied to the reactor 37 and stabilize the flow of the gas.

[0047] The gas may contain carbon dioxide, which reduces the amount of carbon dioxide emitted into the atmosphere and allows the production of the desired reaction product.

[0048] The chemical reaction system 1 may include a carbon dioxide capture device 20 that captures carbon dioxide by chemical absorption. The gas compressed by the compressor 31 may contain carbon dioxide emitted from the carbon dioxide capture device 20. In the chemical reaction system 1 according to this embodiment, the gas can be circulated by the return flow path 34, so that even if the compressor 31 is operated continuously, the pressure on the suction port side of the compressor 31 can be prevented from becoming too low. Therefore, it is possible to prevent the compressor 31 from sucking in gas inside the carbon dioxide capture device 20 and causing a loss of pressure balance. In addition, a reaction product can be obtained from the carbon dioxide captured by the carbon dioxide capture device 20.

[0049] The chemical reaction system 1 may include a hydrogen supply unit 36 ​​that supplies hydrogen to the reactor 37. Hydrogen can be obtained from water using renewable energy. This allows the entire chemical reaction system 1 to reduce carbon dioxide emissions.

[0050] The reaction product may contain hydrocarbons, which can be used as raw materials for fuel, plastics, etc., since hydrocarbons can be obtained by the chemical reaction system 1.

[0051] In the present embodiment, an example has been described in which the gas compressed by the compressor 31 contains carbon dioxide. However, the gas compressed by the compressor 31 may contain other chemical components, such as carbon monoxide, instead of carbon dioxide.

[0052] Furthermore, in the present embodiment, an example has been described in which the gas compressed by the compressor 31 contains carbon dioxide emitted from the carbon dioxide capture device 20. However, the compressor 31 may directly compress the gas emitted from the carbon dioxide generation source 10 without going through the carbon dioxide capture device 20.

[0053] Although several embodiments have been described, the embodiments can be modified or varied based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined, unless they contradict each other.

[0054] This disclosure can contribute, for example, to Goal 13 of the United Nations-led Sustainable Development Goals (SDGs), "Take urgent action to combat climate change and its impacts." [Explanation of symbols]

[0055] 1. Chemical reaction system 20 Carbon dioxide capture equipment 31 Compressor 32 Tank 33 Flow rate adjustment section 34 Return flow path 35 Pressure adjustment section 36 Hydrogen supply unit 37 Reactor

Claims

1. A compressor for compressing a gas containing carbon dioxide; a flow rate adjusting unit that adjusts the flow rate of the gas compressed by the compressor; a return flow path for returning the gas compressed by the compressor to an intake port of the compressor; a pressure adjusting unit provided in the return flow path and adjusting the pressure of the gas compressed by the compressor; a reactor for producing a reaction product containing hydrocarbons from the gas whose flow rate is adjusted by the flow rate adjustment unit; A chemical reaction system comprising:

2. 10. The chemical reaction system according to claim 1, further comprising a tank for absorbing pressure fluctuations of the gas compressed by the compressor.

3. Equipped with a carbon dioxide capture device that captures carbon dioxide using a chemical absorption method, 3. The chemical reaction system according to claim 1, wherein the gas compressed by the compressor contains carbon dioxide released from the carbon dioxide capture device.

4. The chemical reaction system according to any one of claims 1 to 3, further comprising a hydrogen supply unit that supplies hydrogen to the reactor.

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