Reaction apparatus

Abstract

To provide a reaction apparatus capable of reducing heat discharged to the outside of a system.SOLUTION: A reaction apparatus includes a reactor in the inside of which a charge gas flows from an inlet to an outlet and a catalyst disposed on the inside of the reactor, and obtains a product gas by a chemical reaction with heat evolution produced in the inside of the reactor. The reactor includes a first reactor and a second reactor disposed downstream of the first reactor and a heat exchanger to transmit heat from the product gas to the charge gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reactor for obtaining a product gas by an exothermic chemical reaction. [Background technology]

[0002] In a reactor in which an input gas is passed through a reactor containing a catalyst inside and a product gas is obtained by an exothermic chemical reaction, prior art is disclosed in Patent Document 1 in which cooling water pipes and fins are provided in the reactor to cool part of the reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-243425 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, the heat generated by the chemical reaction is removed by cooling water or fins and is discarded outside the reactor system, which is a problem.

[0005] The present invention has been made to solve this problem, and has as its object to provide a reaction apparatus capable of reducing the amount of heat discarded outside the system. [Means for solving the problem]

[0006] A first aspect for achieving this object is a reaction apparatus comprising a reactor through which an input gas flows from an inlet to an outlet, and a catalyst disposed inside the reactor, and which obtains a product gas through an exothermic chemical reaction occurring inside the reactor, the reactor including a first reactor and a second reactor disposed downstream of the first reactor, and comprising a heat exchanger which transfers heat from the product gas to the input gas.

[0007] The second aspect is that, in the first aspect, it further includes a first cooler connected between the first reactor and the second reactor to cool the generated gas, and the heat exchanger includes a first heat exchanger that transfers heat from the generated gas exiting the first reactor and entering the first cooler to the feed gas before entering the second reactor.

[0008] The third aspect is that, in the first or second aspect, the heat exchanger includes a second heat exchanger that transfers heat from the generated gas exiting the first reactor and entering the first cooler to the feed gas before entering the first reactor.

[0009] The fourth aspect is that, in any one of the first to third aspects, it further includes a second heater that heats the second reactor and a second cooler connected downstream of the second reactor to cool the generated gas, and the heat exchanger includes a third heat exchanger that transfers heat from the generated gas exiting the second reactor and entering the second cooler to the feed gas before entering the first reactor.

[0010] The fifth aspect is that, in any one of the first to fourth aspects, it further includes a first heater that heats the first reactor.

[0011] The sixth aspect is that, in any one of the first to fifth aspects, the chemical reaction is a reaction for synthesizing methane from a gas containing at least one of carbon dioxide and carbon monoxide and hydrogen.

Advantages of the Invention

[0012] According to the present invention, since the heat of the generated gas is transferred to the feed gas by the heat exchanger, the generated gas is cooled and the feed gas is heated. Since the feed gas heated by the generated gas enters the reactor and an exothermic reaction occurs, the heat discarded to the outside of the system can be reduced.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a piping system diagram of a reactor 10 in the first embodiment. The reactor 10 includes a reactor 11 through which an input gas flows to obtain a product gas by an exothermic reaction, and a heat exchanger 20 that transfers heat from the product gas to the input gas.

[0015] The reactor 11 includes a first reactor 12 and a second reactor 15 disposed downstream of the first reactor 12. The input gas to the first reactor 12 enters from the inlet 13 and flows through the first reactor 12. The input gas to the second reactor 15 enters from the inlet 16 and flows through the second reactor 15.

[0016] A catalyst 18 is disposed in the reactor 11. The catalyst 18 lowers the activation energy of the chemical reaction of the input gas and facilitates the progress of the chemical reaction. The product gas containing the product of the chemical reaction that occurred in the first reactor 12 exits from the outlet 14 of the first reactor 12. The product gas containing the product of the chemical reaction that occurred in the second reactor 15 exits from the outlet 17 of the second reactor 15.

[0017] The catalyst 18 can be used without limitation as long as it is suitable for various chemical reactions. Examples of the catalyst 18 include powders, pellets, or porous structures in which particles are supported on a carrier. The carrier is exemplified by powders, pellets, or porous structures of oxides containing one or more of alumina, silica, magnesia, titania, zirconia, niobia, silica-alumina, zeolite, and calcium phosphate. The porous structure has air permeability through which the input gas can pass. Also, the input gas passes through the gaps between the powders and pellets. Examples of the particles supported on the carrier include metals containing one or more of Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, and Au.

[0018] There is no restriction on the distribution of catalytic activity in the reactor 11. For example, the catalyst 18 may be arranged so that the catalytic activity is substantially equal over the entire length in the gas flow direction, or the catalyst 18 may be arranged so that the upstream catalytic activity is lower than the downstream catalytic activity. If the carrier, the material of the particles, and the particle diameter of the catalyst 18 are the same, since the catalytic activity is proportional to the surface area of the particles supported by the carrier, the catalytic activity can be lowered by reducing the surface area of the particles supported by the carrier. The catalytic activity can also be lowered by mixing inert particles having no catalytic activity with the catalyst 18 and reducing the amount of the catalyst 18 contained in a certain amount. Examples of the inert particles include powders or pellets of oxides containing one or more of alumina, silica, magnesia, titania, zirconia, niobia, silica-alumina, zeolite, and calcium phosphate.

[0019] Two pipes 22 and 25 are connected to the reactor 11. The pipe 22 is a pipe to which the first raw material gas is supplied, and a control valve 23 and a check valve 24 are arranged in order from upstream to downstream. The pipe 25 is a pipe to which the second raw material gas is supplied, and a control valve 26 and a check valve 27 are arranged in order from upstream to downstream. A shut-off valve 29 is arranged in the gas pipe 28 where the pipes 22 and 25 merge. The first and second raw material gases are set to an optimal mixing ratio through the control valves 23 and 26, respectively, and the mixed gas (input gas) in which the two raw material gases are mixed flows through the gas pipe 28 through the shut-off valve 29.

[0020] In this embodiment, a case where the first raw material gas is hydrogen and the second raw material gas is at least one of carbon dioxide and carbon monoxide will be described. The reactor 11 is set to an appropriate pressure and performs methane production (methanation) represented by the chemical reaction formula of CO2 + 4H2 → CH4 + 2H2O or CO + 3H2 → CH4 + H2O.

[0021] Methanation is an example of a chemical reaction that occurs in the reactor 11, but is not limited thereto. By appropriately selecting the type of raw material gas, the type of catalyst 18, and the reaction conditions, for example, the following chemical reactions can occur in the reactor 11.

[0022] Synthesis gas production by partial oxidation of methane: 2CH4 + O2 → 2CO + 4H2 Methanol synthesis: CO + 2H2 → CH3OH Methanol synthesis: CO2 + 3H2 → CH3OH + H2O Fischer-Tropsch synthesis: CO + 2H2 → -(CH2)- + H2O -(CH2)- means linear hydrocarbon Dimethyl ether synthesis: 2CO + 4H2 → CH3OCH3 + H2O Ammonia synthesis: N2 + 3H2 → 2NH3

[0023] The heat exchanger 20 includes a third heat exchanger 21. The gas pipe 28 is connected to the inlet 13 of the first reactor 12 to guide the feed gas into the first reactor 12. In the gas pipe 28, downstream of the shut-off valve 29 and in the flow direction of the feed gas, the third heat exchanger 21 and the first heater 30 are arranged in sequence. The third heat exchanger 21 transfers heat from the product gas of the second reactor 15 to the feed gas of the first reactor 12. The third heat exchanger 21 performs heat exchange between the cold feed gas flowing through the gas pipe 28 and the hot product gas flowing through the gas pipe 37 (described later). Although there is no limitation on the third heat exchanger 21, a plate heat exchanger that alternately flows the feed gas and the product gas between laminated heat transfer plates for heat exchange is preferred because of its high heat transfer coefficient.

[0024] The first heater 30 heats the feed gas of the first reactor 12. Examples of the first heater 30 include those that heat the heat source by the combustion heat of gas or electricity to heat the gas pipe 28 and those that utilize induction heating. In particular, the first heater 30 that heats the heat source by electricity is preferred because of its high accuracy in temperature control. If the feed gas of the first reactor 12 is at a temperature equal to or higher than the minimum temperature at which the exothermic reaction starts, the exothermic reaction proceeds in the first reactor 12 without heating the first reactor 12 using a heater.

[0025] The gas pipe 31 connected to the outlet 14 of the first reactor 12 allows the product gas of the first reactor 12 to flow through. In the gas pipe 31, a first cooler 32 and a first separator 33 are arranged in sequence in the direction of the flow of the product gas. The first cooler 32 cools the product gas of the first reactor 12 to a temperature below the dew point and condenses the water vapor contained in the product gas. The first separator 33 separates the condensed water from the gas.

[0026] The gas pipe 34 connects between the first separator 33 and the inlet 16 of the second reactor 15. A third heater 35 is arranged in the gas pipe 34 through which the feed gas of the second reactor 15 flows. The third heater 35 heats the feed gas of the second reactor 15 to a temperature above, for example, the lowest temperature at which the exothermic reaction starts. The third heater 35 employs a device with the same mechanism as the first heater 30.

[0027] A second heater 36 is arranged in the second reactor 15. The second heater 36 is arranged between the intermediate position of the entire length of the portion where the catalyst 18 is arranged and the inlet 16, and between the intermediate position of the entire length of the portion where the catalyst 18 is arranged and the outlet 17. The second heater 36 ensures the reaction rate of the second reactor 15 where a large amount of the product of the chemical reaction exists. Examples of the second heater 36 include those that heat the catalyst 18 by heating the heat source with the combustion heat of gas or electricity, and those that utilize induction heating. In particular, the second heater 36 that heats the heat source with electricity is preferred because of its high accuracy in temperature control.

[0028] The gas pipe 37 connected to the outlet 17 of the second reactor 15 allows the product gas of the second reactor 15 to flow through. The second heater 36 heats the catalyst 18 so that the temperature of the product gas entering the gas pipe 37 from the outlet 17 falls within a predetermined range (for example, ±10°C). The quality of the product gas can be stabilized by the temperature control of the catalyst 18 by the second heater 36.

[0029] The third heat exchanger 21, the second cooler 38, and the second separator 39 are arranged in this order in the direction of the product gas flow in the gas pipe 37. The third heat exchanger 21 transfers the heat of the product gas flowing in the gas pipe 37 to the input gas flowing in the gas pipe 28, heating the input gas. The second cooler 38 cools the product gas from the second reactor 15 to a temperature below the dew point, condensing the water vapor contained in the product gas. The second separator 39 separates the condensed water from the gas. The product (gas) from which the water has been separated flows in a gas pipe 40 connected to the second separator 39.

[0030] A chemical reaction occurs while the input gas flows through the catalyst 18 of the first reactor 12, and the product gas from the first reactor 12 contains methane, water vapor, and unreacted input gas. Because this chemical reaction is exothermic, the temperature of the product gas from the first reactor 12 is higher than the temperature of the input gas to the first reactor 12. The product gas from the first reactor 12 is cooled to a temperature below the dew point by the first cooler 32, and the first separator 33 separates the condensed water. This reduces the water vapor content of the product gas from the first reactor 12 (the input gas to the second reactor 15), and shifts the equilibrium of the chemical reaction in the second reactor 15 to the right. This facilitates the reaction of the unreacted input gas in the second reactor 15.

[0031] It is preferable that the input gas to the second reactor 15, which has been cooled by the first cooler 32, is heated by the third heater 35 to a temperature equal to or higher than the minimum temperature at which an exothermic reaction starts, because this facilitates the progress of the chemical reaction in the second reactor 15. Since the second reactor 15 is heated by the second heater 36, the reaction rate in the second reactor 15 increases, improving the reaction rate.

[0032] Because the second reactor 15 is heated by the second heater 36, the thermal energy of the product gas of the second reactor 15 heated by the second heater 36 becomes greater than the thermal energy of the input gas to the second reactor 15. The third heat exchanger 21 transfers the thermal energy of the product gas of the second reactor 15 before it leaves the second reactor 15 and enters the second cooler 38 to the input gas to the first reactor 12, thereby reducing the heat of the product gas of the second reactor 15 that is cooled by the second cooler 38 and discarded outside the system. Furthermore, because the product gas of the second reactor 15 is cooled by the third heat exchanger 21, the energy input to the second cooler 38 to cool the product gas of the second reactor 15 can be reduced.

[0033] The first heater 30 can be omitted if the temperature of the input gas to the first reactor 12 is raised by the third heat exchanger 21 to a temperature equal to or higher than the minimum temperature at which an exothermic reaction starts in the first reactor 12. When the first heater 30 is omitted, the increase in the thermal energy of the input gas to the first reactor 12 is due to the thermal energy of the product gas from the second reactor 15 in the third heat exchanger 21. Even if the first heater 30 is not omitted, the input gas to the first reactor 12 is heated by the third heat exchanger 21, so the energy input to the first heater 30 to heat the input gas to the first reactor 12 can be reduced.

[0034] A reaction apparatus 50 in a second embodiment will be described with reference to Fig. 2. In the first embodiment, the case where the heat exchanger 20 includes the third heat exchanger 21 will be described. In contrast, in the second embodiment, the case where the heat exchanger 20 includes the third heat exchanger 21 and the first heat exchanger 51 will be described. The same parts as those described in the first embodiment will be assigned the same reference numerals, and the following description will be omitted.

[0035] FIG. 2 is a piping system diagram of the reactor 50 in the second embodiment. The reactor 50 includes a first heat exchanger 51. The first heat exchanger 51 is disposed between the first reactor 12 and the first cooler 32 in the gas pipe 31, and between the first separator 33 and the third heater 35 in the gas pipe 34. The first heat exchanger 51 transfers the heat of the product gas of the first reactor 12, which exits the first reactor 12 and enters the first cooler 32, to the feed gas of the second reactor 15. Since the feed gas of the second reactor 15 is heated by the first heat exchanger 51, the energy input to the third heater 35 to heat the feed gas of the second reactor 15 can be reduced.

[0036] If the temperature of the feed gas of the second reactor 15 is equal to or higher than the minimum temperature at which the exothermic reaction starts in the second reactor 15 by the first heat exchanger 51, the third heater 35 can be omitted. When the third heater 35 is omitted, the increment of the thermal energy of the feed gas of the second reactor 15 is due to the thermal energy of the product gas of the first reactor 12 in the first heat exchanger 51.

[0037] The thermal energy of the product gas of the first reactor 12, which exits the first reactor 12 and enters the first cooler 32, is transferred by the first heat exchanger 51 to the feed gas of the second reactor 15. Therefore, the heat of the product gas of the first reactor 12, which is cooled by the first cooler 32 and discarded outside the system, can be reduced. Further, since the product gas of the first reactor 12 is cooled by the first heat exchanger 51, the energy input to the first cooler 32 to cool the product gas of the first reactor 12 can be reduced.

[0038] The reactor 60 in the third embodiment will be described with reference to FIG. 3. In the second embodiment, the case where the heat exchanger 20 includes the third heat exchanger 21 and the first heat exchanger 51 has been described. In contrast, in the third embodiment, the case where the heat exchanger 20 includes the third heat exchanger 21 and the second heat exchanger 61 will be described. For the parts that are the same as those described in the first embodiment, the same reference numerals are given and the following description is omitted.

[0039] FIG. 3 is a piping system diagram of the reactor 60 in the third embodiment. The reactor 60 includes a second heat exchanger 61. The second heat exchanger 61 is disposed between the first reactor 12 and the first cooler 32 of the gas pipe 31, and between the third heat exchanger 21 and the first heater 30 of the gas pipe 28. The second heat exchanger 61 transfers the heat of the product gas of the first reactor 12 that exits the first reactor 12 and enters the first cooler 32 to the feed gas of the first reactor 12.

[0040] Since the heat energy of the product gas of the first reactor 12 that exits the first reactor 12 and enters the first cooler 32 is transferred by the second heat exchanger 61 to the feed gas of the first reactor 12, the heat of the product gas of the first reactor 12 that is cooled by the first cooler 32 and discarded outside the system can be reduced. Furthermore, since the product gas of the first reactor 12 is cooled by the second heat exchanger 61, the energy input to the first cooler 32 to cool the product gas of the first reactor 12 can be reduced.

[0041] Since the feed gas of the first reactor 12 is heated by the second heat exchanger 61, the energy consumption of the first heater 30 that heats the feed gas of the first reactor 12 can be reduced. If the temperature of the feed gas of the first reactor 12 is equal to or higher than the minimum temperature at which an exothermic reaction starts in the first reactor 12 by the second heat exchanger 61, the first heater 30 can be omitted. When the first heater 30 is omitted, the increment of the heat energy of the feed gas of the first reactor 12 is due to the heat energy of the product gas of the second reactor 15 in the third heat exchanger 21 and the heat energy of the product gas of the first reactor 12 in the second heat exchanger 61.

[0042] As described above, the present invention has been described based on the embodiments. However, it can be easily inferred that the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention.

[0043] In the embodiment, the case where the reactor 11 includes the first reactor 12 and the second reactor 15 has been described, but it is not necessarily limited to this. It is of course possible to further connect one or more reactors downstream of the second reactor 15, or to further connect one or more reactors upstream of the first reactor 12.

[0044] In the embodiment, the case where the heater for heating the first reactor 12 is not arranged in the first reactor 12 has been described, but it is not necessarily limited to this. It is of course possible to arrange a heater for heating the catalyst 18 accommodated in the first reactor 12 in the first reactor 12.

Explanation of Reference Numerals

[0045] 10, 50, 60 Reaction device 11 Reactor 12 First reactor 13 Inlet 14 Outlet 15 Second reactor 16 Inlet 17 Outlet 18 Catalyst 20 Heat exchanger 21 Third heat exchanger 30 First heater 32 First cooler 36 Second heater 38 Second cooler 51 First heat exchanger 61 Second heat exchanger

Claims

1. A reactor in which the input gas flows inward from the inlet toward the outlet, and a catalyst disposed inside the reactor, and comprising a reaction apparatus for obtaining a product gas by a chemical reaction accompanied by heat generation occurring inside the reactor, wherein the reactor includes a first reactor and a second reactor disposed downstream of the first reactor, the reaction apparatus comprising a heat exchanger that transfers heat from the product gas to the input gas.

2. further comprising a first cooler connected between the first reactor and the second reactor for cooling the product gas, the reaction apparatus according to claim 1, wherein the heat exchanger includes a first heat exchanger that transfers heat from the product gas exiting the first reactor and entering the first cooler to the input gas before entering the second reactor.

3. further comprising a first cooler connected between the first reactor and the second reactor for cooling the product gas, the reaction apparatus according to claim 1, wherein the heat exchanger includes a second heat exchanger that transfers heat from the product gas exiting the first reactor and entering the first cooler to the input gas before entering the first reactor.

4. further comprising a second heater for heating the second reactor, and a second cooler connected downstream of the second reactor for cooling the product gas, the reaction apparatus according to any one of claims 1 to 3, wherein the heat exchanger includes a third heat exchanger that transfers heat from the product gas exiting the second reactor and entering the second cooler to the input gas before entering the first reactor.

5. the reaction apparatus according to claim 4, further comprising a first heater for heating the first reactor.

6. the reaction apparatus according to any one of claims 1 to 3, wherein the chemical reaction is a reaction for synthesizing methane from a gas containing at least one of carbon dioxide and carbon monoxide and hydrogen.

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