Reaction apparatus

Abstract

The present invention provides a reaction apparatus that can reduce the amount of heat to be discarded out of the system. A reaction apparatus (10) comprises: a reactor (11) inside which an introduced gas flows from an inlet to an outlet; and a catalyst (18) disposed inside the reactor. The reaction apparatus obtains product gas through an exothermic chemical reaction occurring inside the reactor. The reactor includes a first reactor (12) and a second reactor (15) disposed downstream of the first reactor, and a heat exchanger (20) is provided to transfer heat from the product gas to the introduced gas.

Description

Reactor

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

[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, a prior art technique is disclosed in Patent Document 1 in which cooling water pipes and fins are provided in the reactor to cool part of the reactor.

[0003] Japanese Patent Application Laid-Open No. 2000-243425

[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.

[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] In a second aspect, the method of the first aspect further includes a first cooler connected between the first reactor and the second reactor to cool the product gas, and the heat exchanger includes a first heat exchanger that transfers heat from the product gas that has left the first reactor and before entering the first cooler to the input gas before entering the second reactor.

[0008] In a third aspect, in the first or second aspect, the heat exchanger includes a second heat exchanger that transfers heat from the product gas that leaves the first reactor and before entering the first cooler to the input gas that enters the first reactor.

[0009] A fourth aspect is the method according to any one of the first to third aspects, 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, and the heat exchanger includes a third heat exchanger for transferring heat from the product gas that has left the second reactor and is not entering the second cooler to the input gas that is not entering the first reactor.

[0010] A fifth aspect is the method according to any one of the first to fourth aspects, further comprising a first heater for heating the first reactor.

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

[0012] According to the present invention, the heat of the produced gas is transferred to the input gas by the heat exchanger, so that the produced gas is cooled and the input gas is heated. The input gas heated by the produced gas enters the reactor and an exothermic reaction occurs, so that the heat discarded outside the system can be reduced.

[0013] 1 is a piping diagram of a reaction apparatus according to a first embodiment; FIG. 2 is a piping diagram of a reaction apparatus according to a second embodiment; FIG. 3 is a piping diagram of a reaction apparatus according to a third embodiment.

[0014] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a piping diagram of a reaction apparatus 10 according to a first embodiment. The reaction apparatus 10 includes a reactor 11 through which an input gas flows and which produces a product gas by an exothermic reaction, and a heat exchanger 20 which 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. An input gas to the first reactor 12 enters through an inlet 13 and flows through the first reactor 12. An input gas to the second reactor 15 enters through an inlet 16 and flows through the second reactor 15.

[0016] A catalyst 18 is disposed in reactor 11. Catalyst 18 lowers the activation energy of the chemical reaction of the input gas, making it easier for the chemical reaction to proceed. A product gas containing the products of the chemical reaction occurring in first reactor 12 exits from outlet 14 of first reactor 12. A product gas containing the products of the chemical reaction occurring in second reactor 15 exits from outlet 17 of second reactor 15.

[0017] The catalyst 18 may be any suitable catalyst for various chemical reactions without limitation. Examples of the catalyst 18 include powders, pellets, and porous structures in which particles are supported on a carrier. Examples of the carrier include powders, pellets, and 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 permeability that allows the input gas to pass through. The input gas also passes through the gaps between the powder 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 limit to the distribution of catalytic activity within the reactor 11. For example, the catalyst 18 may be arranged so that the catalytic activity is approximately equal throughout the entire length in the gas flow direction, or so that the catalytic activity upstream is lower than the catalytic activity downstream. Since the catalytic activity of the catalyst 18 is proportional to the surface area of ​​the particles supported by the support, provided that the materials and particle diameters of the support and particles are the same, the catalytic activity can be reduced by reducing the surface area of ​​the particles supported by the support. The catalytic activity can also be reduced by mixing inactive particles with the catalyst 18 to reduce the amount of catalyst 18 contained in a given amount. Examples of inactive particles include oxide powders or pellets 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. Pipe 22 is a pipe through which a first raw material gas is supplied, and a control valve 23 and a check valve 24 are arranged in this order from upstream to downstream. Pipe 25 is a pipe through which a second raw material gas is supplied, and a control valve 26 and a check valve 27 are arranged in this order from upstream to downstream. A gate valve 29 is arranged in gas pipe 28 where pipes 22 and 25 join. The first and second raw material gases are set to an optimal mixing ratio through control valves 23 and 26, respectively, and a mixed gas (input gas) obtained by mixing the two raw material gases flows through gas pipe 28 through gate valve 29.

[0020] In this embodiment, the first raw material gas is hydrogen, and the second raw material gas is at least one of carbon dioxide and carbon monoxide. The reactor 11 is set at an appropriate pressure, and CO ２ +4H ２ →CH ４ +2H ２ O or CO + 3H ２ →CH ４ +H ２ Methane production (methanation) is carried out, which is represented by the chemical reaction formula O.

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

[0022] Partial oxidation of methane to syngas: 2CH ４ +O ２ → 2CO + 4H ２ Methanol synthesis: CO + 2H ２ →CH ３ OH Methanol synthesis: CO ２ +3H ２ →CH ３ OH+H ２ Fischer-Tropsch synthesis: CO + 2H ２ →-(CH ２ ) - + H ２ O-(CH ２ ) - means straight chain hydrocarbon Dimethyl ether synthesis: 2CO + 4H ２ →CH ３ OCH３ +H ２ O Ammonia synthesis: N ２ +3H ２ →2NH ３

[0023] The heat exchanger 20 includes a third heat exchanger 21. A gas pipe 28 is connected to the inlet 13 of the first reactor 12 and introduces the input gas into the first reactor 12. The third heat exchanger 21 and a first heater 30 are arranged in this order in the gas pipe 28, downstream of the gate valve 29, in the direction of the input gas flow. The third heat exchanger 21 transfers heat from the product gas of the second reactor 15 to the input gas of the first reactor 12. The third heat exchanger 21 exchanges heat between the low-temperature input gas flowing through the gas pipe 28 and the high-temperature product gas flowing through a gas pipe 37 (described later). There are no limitations on the third heat exchanger 21, but a plate-type heat exchanger, which exchanges heat by alternately flowing the input gas and the product gas between stacked heat transfer plates, is preferred because of its high heat transfer coefficient.

[0024] The first heater 30 heats the input gas to the first reactor 12. Examples of the first heater 30 include a heater that uses gas combustion heat or electricity to heat a heat source and heats the gas pipe 28, and a heater that uses induction heating. In particular, a first heater 30 that uses electricity to heat a heat source is preferred because it provides highly accurate temperature control. If the input gas to the first reactor 12 has a temperature equal to or higher than the minimum temperature at which an exothermic reaction begins, the exothermic reaction will proceed in the first reactor 12 without heating the first reactor 12 using a heater.

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

[0026] A gas pipe 34 connects the first separation device 33 and the inlet 16 of the second reactor 15. A third heater 35 is disposed in the gas pipe 34, through which the input gas to the second reactor 15 flows. The third heater 35 heats the input gas to the second reactor 15, for example, to a temperature equal to or higher than the minimum temperature at which an exothermic reaction starts. The third heater 35 employs a device having a mechanism similar to that of the first heater 30.

[0027] A second heater 36 is disposed in the second reactor 15. The second heater 36 is disposed between the inlet 16 and a midpoint of the overall length of the portion where the catalyst 18 is disposed, and between the midpoint of the overall length of the portion where the catalyst 18 is disposed and the outlet 17. The second heater 36 ensures a high reaction rate in the second reactor 15, where a large amount of chemical reaction products are present. Examples of the second heater 36 include one that heats the catalyst 18 by using gas combustion heat or electricity as a heat source, and one that uses induction heating. In particular, a second heater 36 that heats a heat source by electricity is preferred because of its high accuracy of temperature control.

[0028] The product gas from the second reactor 15 flows through a gas pipe 37 connected to the outlet 17 of the second reactor 15. A 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). Temperature control of the catalyst 18 by the second heater 36 can stabilize the quality of the product gas.

[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 water has been separated flows in a gas pipe 40 connected to the second separator 39.

[0030] Due to a chemical reaction that occurs while the input gas flows through the catalyst 18 of the first reactor 12, the product gas of the first reactor 12 contains methane, water vapor, and unreacted input gas. Because this chemical reaction is exothermic, the temperature of the product gas of the first reactor 12 is higher than the temperature of the input gas to the first reactor 12. The product gas of 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 of 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 makes it easier for the unreacted input gas to react 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, and the reaction rate improves.

[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 of 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 that the energy input to the first heater 30 for heating 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] 2 is a piping diagram of a reaction apparatus 50 according to the second embodiment. The reaction apparatus 50 includes a first heat exchanger 51. The first heat exchanger 51 is disposed between the first reactor 12 and the first cooler 32 on the gas pipe 31, and between the first separator 33 and the third heater 35 on the gas pipe 34. The first heat exchanger 51 transfers heat from the product gas of the first reactor 12 before it leaves the first reactor 12 and enters the first cooler 32 to the input gas of the second reactor 15. Because the input gas of the second reactor 15 is heated by the first heat exchanger 51, the energy input to the third heater 35 for heating the input gas of the second reactor 15 can be reduced.

[0036] The third heater 35 can be omitted if the temperature of the input gas to the second reactor 15 is raised by the first heat exchanger 51 to a temperature equal to or higher than the minimum temperature at which an exothermic reaction starts in the second reactor 15. When the third heater 35 is omitted, the increase in the thermal energy of the input gas to 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 from the first reactor 12 before it leaves the first reactor 12 and enters the first cooler 32 is transferred to the input gas of the second reactor 15 by the first heat exchanger 51. This reduces the heat of the product gas from the first reactor 12 that is cooled by the first cooler 32 and discarded outside the system. Furthermore, because the product gas from 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 from the first reactor 12 can be reduced.

[0038] A reaction apparatus 60 in a 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 will be 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. The same parts as those described in the first embodiment will be assigned the same reference numerals, and the following description will be omitted.

[0039] 3 is a piping diagram of a reaction apparatus 60 in the third embodiment. The reaction apparatus 60 includes a second heat exchanger 61. The second heat exchanger 61 is disposed between the first reactor 12 and the first cooler 32 on the gas pipe 31, and between the third heat exchanger 21 and the first heater 30 on the gas pipe 28. The second heat exchanger 61 transfers heat of the product gas of the first reactor 12 before it leaves the first reactor 12 and enters the first cooler 32 to the input gas of the first reactor 12.

[0040] The thermal energy of the product gas of the first reactor 12 before it leaves the first reactor 12 and enters the first cooler 32 is transferred to the input gas of the first reactor 12 by the second heat exchanger 61, so that 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, because 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 input gas to the first reactor 12 is heated by the second heat exchanger 61, it is possible to reduce the energy consumption of the first heater 30 that heats the input gas to the first reactor 12. If the temperature of the input gas to the first reactor 12 is raised by the second heat exchanger 61 to a temperature equal to or higher than the minimum temperature at which an exothermic reaction starts in the first reactor 12, the first heater 30 can be omitted. 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 of the second reactor 15 in the third heat exchanger 21 and the thermal energy of the product gas of the first reactor 12 in the second heat exchanger 61.

[0042] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0043] In the embodiment, the reactor 11 includes the first reactor 12 and the second reactor 15, but this 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, a case has been described in which a heater for heating the first reactor 12 is not disposed in the first reactor 12, but this is not necessarily limited to this. It is of course possible to dispose a heater for heating the catalyst 18 housed in the first reactor 12 in the first reactor 12.

[0045] 10, 50, 60 Reactor 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 feed gas flows inward from an inlet toward an outlet, and a catalyst disposed inside the reactor, and 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, and the reaction apparatus includes a heat exchanger for transferring heat from the product gas to the feed gas.

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

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

4. The reaction apparatus according to any one of claims 1 to 3, 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, wherein the heat exchanger includes a third heat exchanger for transferring heat from the product gas exiting the second reactor and entering the second cooler to the feed 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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