JP2015107943A - Methane manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture methane highly efficiently.SOLUTION: A methane manufacturing apparatus 100 comprises: a plurality of reactors 110 which house a catalyst accelerating methanation reaction; a plurality of communication paths 120 which communicate with adjacent two reactors in the plurality of reactors and send out generated gas generated in a reactor on a previous stage to a reactor on a subsequent stage; a raw material gas introduction part 130 which introduces raw material gas to a reactor on the first stage out of the plurality of reactors; and a cooling part 150 which cools generated gas generated in the reactor on a previous stage in the communication paths to the temperature at which methanation reaction starts, in which the raw material gas introduction part introduces steam into the reactor on the first stage together with raw material gas.

Description

  The present invention relates to a methane production apparatus that produces methane using hydrogen and carbon dioxide as source gases.

A reaction (a methanation reaction) performed in a methane production apparatus for producing methane (CH ₄ ) from hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) is an exothermic reaction. Therefore, in order to promote the methanation reaction, it is necessary to suppress the temperature rise in the reaction field. Therefore, a reaction that contains a catalyst that promotes the methanation reaction and includes a plurality of reactors connected in series, and a product gas generated in one reactor is disposed in the next stage of the one reactor. A methane production apparatus is used that is configured to be sent to a reactor and suppresses the rise in the starting temperature in the reactor in the next stage by cooling the product gas between the reactors (for example, Non-Patent Document 1). .

  Also, by extracting a part of the product gas generated in the reactor, removing water and carbon dioxide from the product gas to make methane rich gas, and returning the methane rich gas to the reactor, the heat capacity in the reactor is increased. Thus, a technique for suppressing the temperature rise of the reaction field in the reactor is also disclosed (for example, Patent Document 1).

Special table 2012-514039 gazette

Energy research Center of the Netherlands, Methanation, http://www.biosng.com/experimental-line-up/methanation/

  However, the technique of Patent Document 1 has a limitation in the production efficiency of methane. Therefore, further improvement in the production efficiency of methane is desired in the methane production apparatus including the plurality of reactors connected in series.

  Then, in view of such a subject, this invention aims at providing the methane manufacturing apparatus which can manufacture methane highly efficiently.

  In order to solve the above problems, the methane production apparatus of the present invention is a methane production apparatus for producing methane using hydrogen and carbon dioxide as raw material gas, and promotes the methanation reaction that is a reaction from raw material gas to methane. A plurality of reactors in which a catalyst is accommodated, and a plurality of communication passages for communicating two adjacent reactors in the plurality of reactors, respectively, and sending a product gas generated in the former reactor to the latter reactor , Among the plurality of reactors, the raw material gas introduction part that introduces the raw material gas into the most upstream reactor, and the product gas generated in the previous reactor in the communication path is equal to or higher than the temperature at which the methanation reaction starts, And a cooling section that cools below the temperature at which the methanation reaction stops, and the raw material gas introduction section introduces water vapor together with the raw material gas into the most upstream reactor.

  Further, the amount of water vapor introduced by the source gas introduction unit may be greater than 0 times and less than or equal to 1.2 times the total amount of source gas.

  Further, among the plurality of reactors, the amount of methane produced is increased based on the result of the gas composition measuring unit that measures the composition of the product gas sent from the reactor at the rearmost stage and the gas composition measuring unit. And a central control unit that controls the amount of water vapor introduced by the source gas introduction unit.

  Further, the number of stages of the reactor may be 5 or less.

  Moreover, it is good also as providing further the water removal part which removes water from the product gas cooled by the cooling part between a cooling part and the reactor of a back | latter stage among at least any one of the communicating paths.

  According to the present invention, methane can be produced with high efficiency.

It is a figure explaining the conventional methane manufacturing apparatus. It is a figure explaining the relationship between the stage number of a reactor, the reaction rate, and the temperature which reaches | attains an equilibrium state. It is a figure for demonstrating the structure of the methane manufacturing apparatus concerning embodiment. It is a figure explaining the relationship between water vapor introduction amount and reaction rate (%). It is a figure explaining the relationship between X and reaction rate (%) in each stage number of a reactor. It is a figure for demonstrating the methane manufacturing apparatus concerning a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

…式（１） The methanation reaction (the following formula (1)) used when producing methane from raw material gases (hydrogen and carbon dioxide) is an exothermic reaction. Therefore, when the reaction field is not cooled (heat removal), the methanation reaction proceeds, and when the reaction field reaches a predetermined temperature, the methanation reaction reaches an equilibrium state (stops), and more methane Is no longer manufactured.

... Formula (1)

  FIG. 1 is a diagram for explaining a conventional methane production apparatus 10. In the conventional methane production apparatus 10 shown in FIG. 1, a plurality of reactors 12 are connected in series by a communication path 14, and not a reactor 12 itself but a communication path 14 that connects adjacent reactors 12 to each other. 16 is disposed, and the product gas is cooled in the cooling unit 16 (between the reactors 12). With this configuration, the temperature of the reaction field in the reactor 12 arranged in the next stage is lowered, and the production efficiency of methane (reaction rate of methanation reaction) is increased.

  In the conventional methane production apparatus 10, the product gas generated in one reactor 12 is sent to the next-stage reactor 12, and further methanation reaction proceeds in the next-stage reactor 12. As the number of stages (number) of the vessel 12 increases, the reaction rate (the ratio of the raw material gas consumed by the methanation reaction to the amount of raw material gas introduced, also referred to as conversion) increases. Hereinafter, the relationship between the number of reactors 12 and the reaction rate will be described in detail.

Table 1 is a table showing the relationship between the number of stages of the reactor 12, the reaction rate, and the temperature at which the equilibrium state is reached. FIG. 2 is a diagram for explaining the relationship between the number of stages of the reactor 12 and the reaction rate and the temperature reaching the equilibrium state. The horizontal axis represents the reaction rate (%), and the vertical axis represents the temperature reaching the equilibrium state ( ° C). In FIG. 2, the relationship between the temperature at which the equilibrium state is reached and the reaction rate is indicated by a broken line, the temperature rise in each reactor 12 is indicated by a solid arrow, and the product gas produced by cooling the product gas between the reactors 12. The temperature drop is indicated by a dashed-dotted arrow. The lowest temperature at which the methanation reaction starts is 200 ° C. That is, at less than 200 ° C., the methanation reaction does not proceed. Therefore, the raw material gas introduced into the first-stage reactor 12 is 200 ° C.

  As shown in Table 1 and FIG. 2, for example, the first-stage reactor 12 rises to 589 ° C., and the reaction rate remains at 39.5%. That is, the methanation reaction reaches an equilibrium state at 589 ° C. The second-stage reactor 12 rises to 518 ° C., the reaction rate is 61.3%, the third-stage reactor 12 rises to 440 ° C., and the reaction rate is 78.3%. The fourth-stage reactor 12 rises to 360 ° C., the reaction rate is 89.7%, the fifth-stage reactor 12 rises to 287 ° C., the reaction rate is 95.7%, The first reactor 12 rises to 234 ° C. and the reaction rate becomes 98.0%, and the seventh-stage reactor 12 rises to 210 ° C. and the reaction rate becomes 98.7%.

  In Table 1 and FIG. 2 described above, it is assumed that the product gas generated in the preceding reactor 12 is cooled to 200 ° C. (the lowest temperature at which the methanation reaction starts) in the communication path 14. Note that since the catalyst is not accommodated in the communication path 14, the methanation reaction does not proceed when the cooling unit 16 cools the generated gas in the communication path 14.

  Thus, the reaction rate increases as the number of stages of the reactor 12 is increased. However, since the methanation reaction is an exothermic reaction and an equilibrium reaction as shown in the above formula (1), the conventional methane In the production apparatus 10, the production efficiency (reaction rate) of methane is determined to the value shown in Table 1 above according to the number of stages of the reactor 12. In this embodiment, in a methane production apparatus configured to include a plurality of reactors communicated in series, a new configuration is added to provide a reactor having the same number of stages as the conventional methane production apparatus 10. Even if it exists, the production efficiency of methane is improved. Hereinafter, the methane production apparatus 100 according to the present embodiment will be described in detail.

(Methane production apparatus 100)
FIG. 3 is a diagram for explaining the configuration of the methane production apparatus 100 according to the present embodiment. As shown in FIG. 3, the methane production apparatus 100 includes a plurality of reactors 110, a plurality of communication passages 120, a raw material gas introduction unit 130, a cooling unit 150, a gas composition measurement unit 170, and a central control unit 180. It is comprised including. In FIG. 3, the substance flow is indicated by solid arrows, and the signal flow is indicated by broken arrows.

  Two adjacent reactors in the plurality of reactors 110 are connected by a communication path 120. Each reactor 110 contains a catalyst that promotes a methanation reaction, which is a reaction from raw material gas (hydrogen, carbon dioxide) to methane, and a plurality of reactors 110 are connected by a raw material gas introduction unit 130. Among these, when the raw material gas is introduced into the foremost reactor 110, the product gas is first generated in the foremost reactor 110. Note that, as described above, the communication path 120 allows the two adjacent reactors 110 in the plurality of reactors 110 to communicate with each other, and the product gas generated in the upstream reactor 110 is sent to the downstream reactor 110. Therefore, the product gas generated in one reactor 110 is sent to the reactor 110 disposed in the next stage of the one reactor 110 through the communication path 120. Then, the methanation reaction further proceeds in the reactor 110 arranged in the next stage, and a product gas having a higher methane concentration than the product gas produced in the previous reactor 110 is produced.

  In the present embodiment, the raw material gas introduction unit 130 introduces water vapor together with the raw material gas into the first reactor 110 (first reactor 110).

  FIG. 4 is a diagram for explaining the relationship between the amount of water vapor introduced and the reaction rate (%). In FIG. 4, X = 2.0 times is a square, X = 0.8 times is a circle, X = 0.2 times is a triangle, and X = 0 times, that is, when water vapor is not introduced It shows with. Here, the magnification of the total amount of water vapor with respect to the total amount of raw material gas introduced by the raw material gas introduction unit 130 is “X”.

  As shown in FIG. 4, a configuration in which one reactor 110 is provided (one-stage configuration), a configuration in which two reactors 110 are provided (two-stage configuration), a configuration in which three reactors 110 are provided (three-stage configuration), and a configuration in which four reactors 110 are provided ( In the four-stage configuration, as X increases, the reaction rate in the last-stage reactor 110 increases. This is because the heat capacity in each reactor 110 can be increased by introducing water vapor, and the temperature increase per unit time of the reaction field in each reactor 110 can be suppressed.

  Therefore, when the number of stages of the reactor 110 is 4 or less, the source gas introduction unit 130 increases the reaction rate in the last stage reactor 110 if the amount of steam introduced is increased.

  On the other hand, as shown in FIG. 4, when the number of stages of the reactor 110 is five or more, the reaction rate in the last-stage reactor 110 decreases when the amount of steam introduced is increased. This is thought to be due to the fact that the equilibrium state of the methanation reaction collapses due to the introduction of water vapor, and the reaction from the right side to the left side of the formula (1) is promoted (the equilibrium moves to the left).

  FIG. 5 is a diagram illustrating the relationship between X and the reaction rate (%) in each stage number of the reactor 110. As shown in FIG. 5, in the configuration in which seven reactors 110 are provided (seven-stage configuration) and the configuration in which six reactors 110 are provided (six-stage configuration), the reaction rate decreases as X increases. To do.

  On the other hand, in the configuration in which five reactors 110 are provided (5-stage configuration), the reaction rate increases as X increases up to X = 0.8, but when X> 0.8, X increases. Then, the reaction rate gradually decreases, and when X> 2.0, the reaction rate is lower than when water vapor is not introduced (X = 0).

  Similarly, in the configuration in which four reactors 110 are provided (four-stage configuration), the reaction rate increases as X increases until X = 1.2, but when X> 1.2, X becomes The reaction rate gradually decreases as it rises.

  Therefore, the number of stages of the reactor 110 in the methane production apparatus 100 is preferably at least 5 or less (2 to 5).

  Further, as described above, in the methane production apparatus 100 having a 2 to 5 stage configuration, the reaction rate in the last stage reactor 110 is improved by increasing the introduction amount up to a predetermined water vapor amount. However, when X> 1.2, the capacity of the reactor 110 must be increased, and the cost required for the reactor 110 is significantly increased, and the cost effectiveness becomes low. Moreover, since the occupation volume of the reactor 110 becomes large, the installation area of the methane production apparatus 100 itself becomes large, and there is a problem that the installation location is limited.

  Therefore, the amount of water vapor introduced by the source gas introduction unit 130 is preferably greater than 0 and less than or equal to 1.2 times the total amount of source gas. With this configuration, it is possible to improve the reaction rate while minimizing the capacity of the reactor 110.

  Referring back to FIG. 3, the cooling unit 150 cools the product gas generated in the preceding reactor in the communication path 120 to a temperature at which the methanation reaction starts (here, 200 ° C.).

  With the configuration including the cooling unit 150, the temperature of the reaction field in the reactor 110 disposed in the next stage can be lowered, and the production efficiency of methane (reaction rate of methanation reaction) can be increased.

  The gas composition measuring unit 170 measures the composition of the product gas sent from the reactor 110 at the rearmost stage among the plurality of reactors 110.

  The central control unit 180 is composed of a semiconductor integrated circuit including a CPU (central processing unit), reads programs and parameters for operating the CPU itself from the ROM, and cooperates with the RAM as a work area and other electronic circuits. Thus, the entire methane production apparatus 100 is managed and controlled.

  In the present embodiment, the central control unit 180 controls the amount of water vapor introduced by the source gas introduction unit 130 based on the measurement result by the gas composition measurement unit 170 so that the production amount of methane increases. With such a configuration, it is possible to introduce an appropriate amount of water vapor so as to improve the methane content in the finally produced product gas.

  As described above, according to the methane production apparatus 100 according to the present embodiment, it is possible to produce methane with high efficiency with a simple configuration in which water vapor is introduced together with the raw material gas.

  In addition, since water vapor can be condensed into a liquid at less than 100 ° C., it can be easily separated from the product gas. Furthermore, since water vapor does not contain carbon, carbon does not deposit on the catalyst, and a situation in which the catalyst deteriorates can be avoided.

(Modification)
As described above, when steam is introduced into the reactor 110, the heat capacity increases, but the equilibrium state of the methanation reaction is disrupted, and the reaction from the right side to the left side of the above formula (1) is promoted (the equilibrium is left). Moving). Therefore, water is removed after water vapor is introduced into the reactor 110 by the source gas introduction unit 130 and the methanation reaction is performed to some extent by the plurality of reactors 110.

  FIG. 6 is a diagram for explaining a methane production apparatus 200 according to a modification. As shown in FIG. 6, the methane production apparatus 200 includes a plurality of reactors 110, a plurality of communication passages 120, a raw material gas introduction unit 130, a cooling unit 150, a gas composition measurement unit 170, and a central control unit 180. And a water removal unit 260 and a heating unit 270. In FIG. 6, the substance flow is indicated by solid arrows, and the signal flow is indicated by broken arrows.

  In addition, about the component substantially equivalent to the methane production apparatus 100 mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted, and here the water removal part 260 and the heating part 270 are explained in full detail.

  The communication passage 120 that communicates the most downstream reactor 110 (Nth stage) with the reactor 110 (N−1th stage) one stage before the Nth stage reactor 110 has a water removal unit 260 and A heating unit 270 is provided. The water removing unit 260 includes a condensing unit 262 and a gas / liquid separating unit 264. The condensing part 262 cools the product gas produced | generated with the N-1 stage | paragraph reactor 110 to the condensation temperature (dew point) of water, and condenses water. The gas-liquid separation unit 264 separates the condensed water from the product gas cooled by the condensing unit 262. The heating unit 270 disposed on the downstream side of the water removing unit 260 is configured to remove the water-removed gas, which is a product gas after the condensed water is removed by the gas-liquid separating unit 264, to a temperature at which the methanation reaction starts. Heat.

  With the configuration including the water removal unit 260, the amount of water in the product gas generated in the N-1th stage reactor 110 can be reduced. When the amount of water in the product gas decreases, the equilibrium state of the methanation reaction is disrupted, and the reaction from the left side to the right side of the above formula (1) is promoted (the equilibrium moves to the right), and the methanation reaction It is possible to improve the reaction rate (production efficiency of methane). As a result, the methanation reaction can be further promoted in the reactor 110 at the N-th stage as compared with the configuration without the water removal unit 260.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above embodiment, the configuration in which the raw material gas introduction unit 130 introduces water vapor in order to increase the heat capacity of the reactor 110 has been described. However, if the heat capacity of the reactor 110 can be increased and the condensation is performed at less than 200 ° C., the gas introduced by the source gas introduction unit 130 is not limited. For example, a halogen-based gas such as chlorofluorocarbon may be used.

  Moreover, in the said embodiment, it demonstrated and demonstrated the structure which the quantity of the water vapor | steam which the raw material gas introduction part 130 introduce | transduces is larger than 0 time and 1.2 times or less with respect to the total amount of raw material gas. However, the amount of water vapor introduced by the source gas introduction unit 130 is not limited, and may be larger than 1.2 times the total amount of source gas. In this case, the methane production apparatus 100 may be configured such that the reactor 110 has 2 to 4 stages. In addition, in the methane production apparatus 100 in which the number of stages of the reactor 110 is five or more, when the amount of water vapor introduced by the source gas introduction unit 130 is larger than 1.2 times the total amount of the source gas, the water removal unit 260 may be provided.

  Moreover, in the said embodiment, it demonstrated that the number of stages of the reactor 110 which comprises the methane manufacturing apparatus 100 was 5 or less. However, the number of reactors 110 in the methane production apparatus 100 is not limited, and may be 6 or more. In this case, a water removal unit 260 may be provided.

  Further, in the above embodiment, the cooling unit 150 has been described by taking as an example a configuration in which the generated gas is cooled to a temperature at which the methanation reaction starts. However, the cooling unit 150 may cool the product gas to a temperature equal to or higher than the temperature at which the methanation reaction starts and below the temperature at which the methanation reaction stops (the methanation reaction reaches an equilibrium state).

  Moreover, in the said embodiment, although the structure provided with the gas composition measurement part 170 and the central control part 180 was demonstrated, these are not essential structures.

  Further, in the above modification, the water removal unit 260 includes a reactor 110 (N-th stage) at the rearmost stage and a reactor 110 (N-1 stage) one stage before the reactor 110 at the N-th stage. The configuration provided in the communication path 120 that communicates has been described. However, the position of the water removal unit 260 is not limited, and the water removal unit 260 may be provided between the cooling unit 150 and the downstream reactor 110 in at least one of the communication paths 120.

  Moreover, in the said modification, although the water removal part 260 comprised by the condensation part 262 and the gas-liquid separation part 264 was demonstrated, if water can be removed from product gas, there will be no limitation in the structure of the water removal part 260. For example, the water removal unit 260 may be configured with a water separation membrane or the like. In addition, when the water removal part 260 is comprised with the condensation part 262 and the gas-liquid separation part 264, the condensation part 262 functions as a cooling part, but when the water removal part 260 is comprised with a water separation membrane etc., it is separately cooled. It is good to have a part.

  The present invention can be used in a methane production apparatus that produces methane using hydrogen and carbon dioxide as raw material gases.

100, 200 Methane production apparatus 110 Reactor 120 Communication path 130 Source gas introduction part 150 Cooling part 170 Gas composition measurement part 180 Central control part 260 Water removal part 270 Heating part

Claims (5)

A methane production apparatus for producing methane using hydrogen and carbon dioxide as source gases,
A plurality of reactors containing a catalyst for promoting a methanation reaction that is a reaction from the source gas to the methane;
A plurality of communication passages for communicating two adjacent reactors in the plurality of reactors, respectively, and sending the product gas generated in the former reactor to the latter reactor;
Of the plurality of reactors, a raw material gas introduction section for introducing the raw material gas into the most upstream reactor,
A cooling section that cools the product gas generated in the preceding reactor in the communication path to a temperature equal to or higher than a temperature at which the methanation reaction starts and lower than a temperature at which the methanation reaction stops;
With
The raw material gas introduction unit introduces water vapor together with the raw material gas into the foremost reactor.   2. The apparatus for producing methane according to claim 1, wherein the amount of water vapor introduced by the source gas introduction unit is greater than 0 and less than or equal to 1.2 times the total amount of the source gas. Of the plurality of reactors, a gas composition measuring unit for measuring the composition of the product gas sent from the most downstream reactor,
Based on the result by the gas composition measurement unit, a central control unit that controls the amount of water vapor introduced by the source gas introduction unit so that the production amount of the methane increases,
The methane production apparatus according to claim 1, further comprising:   The methane production apparatus according to any one of claims 1 to 3, wherein the number of stages of the reactor is 5 or less.   It further comprises a water removing unit that removes water from the product gas cooled by the cooling unit between the cooling unit and the downstream reactor in at least one of the communication paths. The methane production apparatus according to any one of claims 1 to 4.

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