JP2013136538A - Methanation reaction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a methanation reaction device, capable of avoiding abrupt rise of temperature within the device, in a reaction of converting a raw material gas including much carbon dioxide into methane by the methanation reaction.SOLUTION: This methanation reaction device for producing a gas including methane by feeding hydrogen to the raw material gas including carbon dioxide comprises: a first reactor of feeding the raw material gas and a part of hydrogen; a second reactor of feeding the rest of hydrogen to the reaction mixed gas sent from the first reactor, and adjusting the amount of hydrogen necessary for the reaction; and a third reactor of adjusting the composition of produced gas sent from the second reactor, where the reaction temperature of the first reactor is adjusted by adjusting the amount of hydrogen fed to the reactor.

Description

  The present invention relates to a methanation reaction device for converting carbon dioxide into methane by methanation reaction from a raw material gas containing a large amount of carbon dioxide.

  Many conventional methanation reactors are used to reduce a small amount of carbon monoxide in a raw material gas, and the present inventors first modified by adjusting the reaction temperature and space velocity to a specific range. A method was proposed in which carbon monoxide with a gas content of about 1% was preferentially reduced to 10 ppm, and catalyst particles were mixed with ceramic balls to suppress heat generation and maintain the reaction temperature within the above range (patent) Reference 1, FIG. 4).

  In addition, in order to remove carbon monoxide from hydrogen gas containing carbon monoxide, the reactor is divided into a first reactor and a second reactor, and the reaction temperature and catalyst conditions are adjusted by adjusting the reactor temperature and catalyst conditions. A carbon monoxide removal method that is easy to adjust and does not cause a runaway reaction is shown (Patent Document 2, FIG. 5).

Japanese Patent No. 2852320 JP 2007-254177 A

  However, conventional methanation reactors are mainly used to remove a small amount of carbon monoxide in a gas containing hydrogen gas as a main component, and carbon dioxide is removed from a gas containing a large amount of carbon dioxide by methanation reaction. It does not change to methane. When targeting a gas containing a large amount of carbon dioxide, the amount of methanation reaction is considerably larger than in the past, and there is a danger that the temperature in the reactor will rise rapidly due to the heat of reaction of the methanation reaction in the conventional method. It is difficult to suppress the temperature rise of the catalyst layer.

  As a result of repeated studies to solve the above problems, the present inventors can avoid a rapid increase in the temperature in the apparatus in a reaction in which a raw material gas containing a large amount of carbon dioxide is converted to methane by a methanation reaction. A methanation reactor was developed.

  The invention according to claim 1 is a methanation reactor that supplies hydrogen to a raw material gas containing carbon dioxide to generate a gas containing methane, and a first reactor that supplies a part of the raw material gas and hydrogen; A second reactor for supplying the remainder of hydrogen to the reaction gas mixture coming from the first reactor and adjusting the amount of hydrogen necessary for the reaction, and a third reaction for adjusting the composition of the product gas coming from the second reactor A methanation reaction apparatus comprising a reactor, wherein the reaction temperature of the first reactor is adjusted by adjusting the amount of hydrogen supplied to the reactor.

  The invention according to claim 2 is a methanation reactor that supplies hydrogen to a raw material gas containing carbon dioxide and generates a gas containing methane, and a first reactor that supplies a part of the raw material gas and hydrogen; A second reactor for supplying the remainder of the hydrogen to the reaction gas mixture coming from the first reactor and adjusting the hydrogen flow rate required for the reaction, and a third reaction for adjusting the composition of the product gas coming from the second reactor The methanation reaction apparatus is characterized in that the reaction temperature of the first reactor is adjusted by supplying water vapor to the reactor.

  The invention according to claim 3 is characterized in that the reaction temperature of the first reactor is adjusted by supplying water vapor to the reactor in addition to adjusting the hydrogen supply amount to the reactor. The methanation reactor according to claim 1.

  The invention according to claim 4 is characterized in that the amount of hydrogen to the second reactor is adjusted by calculating from the raw material gas flow rate and the hydrogen flow rate to the first reactor. Methanation reactor.

  The invention according to claim 5 is the methanation reactor according to any one of claims 1 to 4, wherein the composition of the product gas in the third reactor is adjusted by adjusting the temperature or pressure in the reactor. It is.

  The invention according to claim 6 is the methanation reactor according to any one of claims 1 to 5, wherein the first reactor to the third reactor are multi-tubular reactors.

  The invention according to claim 7 is the methanation reactor according to any one of claims 1 to 6, wherein the catalyst layer in the first reactor is diluted by mixing catalyst particles and ceramic balls. It is.

  In the invention according to claim 1, the methanation reactor includes a first reactor that adjusts the reaction temperature, a second reactor that adjusts the amount of hydrogen necessary for the reaction, and a second reactor that adjusts the composition of the generated gas. Since it is divided into 3 reactors, the conditions of each reactor can be adjusted flexibly. Further, by adjusting the reaction temperature of the first reactor by adjusting the amount of hydrogen supplied to the reactor, the temperature increase of the catalyst layer in the reactor can be suppressed within an allowable range.

  In the invention which concerns on Claim 2, since the reaction temperature of a 1st reactor is adjusted by supplying water vapor | steam to the reactor, the rapid temperature rise of the catalyst layer in a reactor can be avoided.

  In the invention according to claim 3, since the reaction temperature of the first reactor is adjusted to adjust the amount of hydrogen supplied to the reactor, and steam is supplied to the reactor, the catalyst layer in the reactor The rapid increase in temperature can be avoided more effectively.

  In the invention according to claim 4, by adjusting the hydrogen flow rate to the second reactor by calculating from the raw material gas flow rate and the hydrogen flow rate to the first reactor, the methanation reaction of carbon dioxide in the raw material gas is performed. Finally, the necessary amount of hydrogen can be supplied.

  In the invention which concerns on Claim 5, the gas composition required on a chemical equilibrium can be adjusted by adjusting the temperature or pressure in a 3rd reactor.

  In the invention which concerns on Claim 6, it can make it easy to adjust the temperature in a reactor by using a multitubular reactor from a 1st reactor to a 3rd reactor.

  In the invention according to claim 7, since the catalyst layer in the first reactor is diluted by mixing the catalyst particles and the ceramic balls, the rapid temperature rise of the catalyst layer in the reactor is more effectively avoided. be able to.

1 is a diagram showing an overall flow of a methanation reaction apparatus of Example 1. FIG. FIG. 3 is a diagram showing an overall flow of the methanation reaction apparatus of Example 2. It is a graph which shows the relationship between the carbon dioxide partial pressure and reaction rate in a nickel-type catalyst. It is a figure which shows the whole flow of the methanation reaction apparatus of patent document 1. FIG. It is a figure which shows the whole flow of the methanation reaction apparatus of patent document 2. FIG.

  Next, the present invention will be specifically described based on examples.

Example 1
The overall flow of the methanation reactor of this example is shown in FIG. In this figure, the present reactor is mainly composed of a first reactor R1, a second reactor R2, a third reactor R3, and an adsorption tower A connected in series.

  A thermometer T1 for measuring the temperature of the catalyst layer is attached to the first reactor R1.

  The hydrogen supply line 1 to the first reactor R1 has a flow meter F1 for measuring the hydrogen supply amount to the first reactor R1, and the hydrogen supply amount to the first reactor R1 is adjusted downstream thereof. And a regulating valve V1 for the purpose. The regulating valve V1 is controlled according to the temperature measured by the thermometer T1.

  A raw material gas supply line 2 for supplying a raw material gas containing a large amount of carbon dioxide to the top of the first reactor R1 is provided with a flow meter F4 for measuring the gas flow rate, and the raw material gas supply line 2 and the hydrogen supply line 1 Downstream of the merging point, there are a raw material gas heater H1 that raises the gas temperature to the temperature required for the reaction, a thermometer T4 for measuring the temperature of the raw material gas, and a pressure gauge P1 for measuring the pressure. They are installed in the order of gas flow.

  At the outlet of the first reactor R1, a cooler C1 for cooling the discharged reaction gas and a tank B1 for storing condensed water are installed under the cooler C1 to remove as much water as possible from the methanation reaction. It is like that.

  A thermometer T2 for measuring the temperature of the catalyst layer is also attached to the second reactor R2.

  The hydrogen supply line 5 to the second reactor R2 has a flow meter F2 for measuring the hydrogen supply amount to the second reactor R2, and the hydrogen supply amount to the second reactor R2 is adjusted downstream thereof. And a regulating valve V2 is installed. The regulating valve V2 is controlled according to the measured values of the flow meter F1, the flow meter F2, and the flow meter F4.

  The reaction gas that has passed through the cooler C1 of the first reactor R1 is sent to the top of the second reactor R2 by the reaction gas transfer line 6. The reaction gas transfer line 6 is provided with a thermometer T5 and a pressure gauge P2 for measuring the inlet temperature and the inlet pressure of the second reactor R2 upstream of the junction with the hydrogen supply line 5. A cooler C2 for cooling the discharged reaction gas at the outlet of the second reactor R2 and a tank B2 for storing condensed water are provided below the cooler C2.

  A thermometer T3 for measuring the temperature of the catalyst layer is also attached to the third reactor R3.

  The reaction gas that has passed through the cooler C2 of the second reactor R2 is sent to the top of the third reactor R3 by the reaction gas transfer line 7. The reaction gas transfer line 7 is provided with a thermometer T6 and a pressure gauge P3 for measuring the inlet temperature and the inlet pressure of the third reactor R3. A cooler C3 for cooling the reaction gas discharged from the outlet of the third reactor R3 and a tank B3 for storing condensed water are provided below the cooler C3.

  The reaction gas that has passed through the cooler C3 of the third reactor R3 is sent to the top of the adsorption tower A by the reaction gas transfer line 8, and the product gas containing methane is extracted from the bottom thereof. The reaction gas transfer line 8 is provided with a thermometer T7 for measuring the inlet temperature of the adsorption tower A.

  Each reactor is a multi-tubular reactor, and a catalyst (for example, Ni-based catalyst) is filled in the reaction tube, and a petroleum-based or silicon-based heat medium is circulated through the heat medium circulation line 3 on the reactor body side. Therefore, the temperature in the reactor is kept constant. A heat medium heater H2 and a pump 4 are installed in the heat medium circulation line 3, and a thermometer T8 is provided between the heat medium heater H2 and the first reactor R1 on the line 3, and the first reactor R1 and the second reaction. A cooler C5 and a thermometer T9 are installed between the reactors R2, and a cooler C6 and a thermometer T10 are installed between the second reactor R2 and the third reactor R3, respectively. Adjusted.

  For example, the catalyst used by the present inventors in Patent Document 1 is a commercially available Ni-based catalyst having a Ni content of 20% and a CaO content of 4 to 6%. The catalyst is 200 to 250 as shown in FIG. It can also be applied to methanation of carbon dioxide in the range of ° C.

  When 100% carbon dioxide is supplied as a raw material gas under a pressure condition of 0.5 to 1.0 MPa in absolute pressure, the raw material gas is heated to a temperature required for the reaction (for example, 200 ° C.) by the raw material gas heater H1. To the first reactor. In the first reactor R1, the temperature on the cylinder side and the tube side is adjusted to the reaction temperature (for example, 220 ° C. to 250 ° C.) with a heat medium. At the same time, hydrogen necessary for the methanation reaction is supplied to the first reactor R1. The methanation reaction of carbon dioxide is an exothermic reaction, and the catalyst layer temperature rises accordingly. If the catalyst temperature becomes too high, there is a risk of exceeding the heat resistance temperature of the constituent devices, the heat medium, and the catalyst. Therefore, the increase in the catalyst layer temperature is suppressed by adjusting the amount of hydrogen supplied to the first reactor R1. For example, when a Ni-based catalyst and a petroleum-based heat medium are used, when the temperature of the catalyst layer before the reaction is 250 ° C., it is necessary to suppress the temperature difference from rising to 50 to 100 ° C. (catalyst layer temperature: 300 to 350 ° C.). is there. The amount of hydrogen supplied to the first reactor R1 is adjusted by opening / closing an adjustment valve V1 controlled according to the temperature measured by the thermometer T1.

  The gas discharged from the first reactor R1 is cooled to a temperature necessary for the reaction of the second reactor R2 by the cooler C1, and then supplied to the second reactor R2. The reaction temperature of the second reactor R2 is set lower (for example, 150 to 220 ° C.) than the reaction temperature of the first reactor R1, and the methane content in the gas composition is increased in a chemical equilibrium. The amount of hydrogen to the second reactor R2 is adjusted by calculating from the raw material gas flow rate and the hydrogen flow rate to the first reactor. Specifically, the hydrogen flow rate to the second reactor R2 is converted from the carbon dioxide flow rate from the raw material gas flow rate and the hydrogen flow rate to the first reactor R1 to the methanation reaction of carbon dioxide supplied stoichiometrically. The amount of hydrogen necessary for the production (stoichiometrically requires 4 times as much hydrogen as carbon dioxide in terms of molar ratio) is calculated and supplied.

  The gas discharged from the second reactor R2 is cooled to a temperature necessary for the reaction of the third reactor R3 by the cooler C2, and then supplied to the third reactor R3. In the third reactor R3, the composition of the product gas is adjusted by adjusting the temperature or pressure in the reactor. Specifically, the catalyst layer temperature is adjusted in a chemical equilibrium from the inlet gas pressure and the catalyst layer temperature to the temperature for adjusting to the gas composition required for the generated gas. For example, when the methane concentration is required to be 99% or more in the dry condition gas exiting the adsorption tower, the reaction temperature is set to 100 to 150 ° C. on the chemical equilibrium under the pressure condition of 0.5 to 1.0 MPa in absolute pressure. adjust.

  In the present embodiment, one each of the first reactor, the second reactor, and the third reactor is shown, but the number of reactors may be increased depending on the length of the reaction tube. For example, two or more first reactors may be used.

  In this example, a commercially available Ni-based catalyst is used, but a Ru-based catalyst for methanation reaction may be used. In this case, however, it is necessary to set temperature and pressure conditions according to the catalyst.

Example 2
The overall flow of another embodiment of the methanation reactor is shown in FIG. In this embodiment, the raw material gas supply line 2 is provided with a water vapor preparation valve V4 between a flow meter F4 for measuring the gas flow rate and a confluence of the raw material gas supply line 2 and the hydrogen supply line 1. A supply line 9 is connected. The steam preparation valve V4 is controlled according to the temperature measured by the thermometer T1.

  Other configurations of the methanation reactor are the same as those in Example 1.

  In the methanation reactor configured as described above, the catalyst supply layer of the first reactor R1 is adjusted by adjusting the amount of hydrogen supplied to the first reactor R1 and supplying water vapor to the reactor R1 as in Example 1. Reduces temperature rise. For example, when a Ni-based catalyst and a petroleum-based heat medium are used, when the temperature of the catalyst layer before the reaction is 250 ° C., it is necessary to suppress the temperature difference from rising to 50 to 100 ° C. (catalyst layer temperature: 300 to 350 ° C.). is there.

  The gas discharged from the first reactor R1 is cooled to a temperature necessary for the reaction of the second reactor R2 by the cooler C1, and then supplied to the second reactor R2. The reaction temperature of the second reactor R2 is set lower (for example, 150 to 220 ° C.) than the reaction temperature of the first reactor R1, and the methane content in the gas composition is increased in a chemical equilibrium. The amount of hydrogen to the second reactor R2 is adjusted by calculating from the raw material gas flow rate and the hydrogen flow rate to the first reactor. Specifically, the hydrogen flow rate to the second reactor R2 is converted from the carbon dioxide flow rate from the raw material gas flow rate and the hydrogen flow rate to the first reactor R1 to the methanation reaction of carbon dioxide supplied stoichiometrically. The amount of hydrogen necessary for the production (stoichiometrically requires 4 times as much hydrogen as carbon dioxide in terms of molar ratio) is calculated and supplied.

  The gas discharged from the second reactor R2 is treated in the same manner as in Example 1.

Claims (7)

  In a methanation reactor that supplies hydrogen to a source gas containing carbon dioxide to produce a gas containing methane, a first reactor that supplies part of the source gas and hydrogen, and a reaction mixture coming from the first reactor A second reactor for supplying the remainder of hydrogen to the gas and adjusting the amount of hydrogen required for the reaction; and a third reactor for adjusting the composition of the product gas coming from the second reactor. The methanation reactor is characterized in that the reaction temperature of is adjusted by adjusting the amount of hydrogen supplied to the reactor.   In a methanation reactor that supplies hydrogen to a source gas containing carbon dioxide to produce a gas containing methane, a first reactor that supplies part of the source gas and hydrogen, and a reaction mixture coming from the first reactor A second reactor for supplying the remainder of the hydrogen to the gas and adjusting the hydrogen flow rate required for the reaction; and a third reactor for adjusting the composition of the product gas coming from the second reactor, The methanation reactor is characterized in that the reaction temperature is adjusted by supplying water vapor to the reactor.   The methanation reaction according to claim 1, wherein the reaction temperature of the first reactor is adjusted by supplying water vapor to the reactor in addition to adjusting the amount of hydrogen supplied to the reactor. apparatus.   4. The methanation reactor according to any one of 1 to 3, wherein the amount of hydrogen to the second reactor is adjusted by calculating from the raw material gas flow rate and the hydrogen flow rate to the first reactor.   5. The methanation reactor according to any one of 1 to 4, wherein the composition of the product gas in the third reactor is adjusted by adjusting the temperature or pressure in the reactor.   The methanation reactor according to any one of claims 1 to 5, wherein the first reactor to the third reactor are multi-tubular reactors.   The methanation reaction apparatus according to any one of claims 1 to 6, wherein the catalyst layer in the first reactor is diluted by mixing catalyst particles and ceramic balls.

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