JP2020093216A - Catalyst reaction device - Google Patents

Abstract

To reduce a temperature of an exothermic reaction without causing deterioration of a reaction rate.SOLUTION: A catalyst reaction device subjects an input gas to an exothermic reaction in the presence of a catalyst. The catalyst has its activity to sequentially rise in an inflow direction of the input gas.SELECTED DRAWING: Figure 2

Description

The present invention relates to a catalytic reactor.

Patent Document 1 below discloses a methanation reaction apparatus that supplies hydrogen to a raw material gas containing carbon dioxide to generate a gas containing methane. The methanation reaction apparatus includes a first reactor that is filled with a catalyst and that causes a methanation reaction of a part of raw material gas and hydrogen to discharge a reaction mixed gas, and a second reactor that adjusts the amount of hydrogen in the reaction mixed gas. And a third reactor that adjusts the composition of the product gas of the second reactor, and controls the amount of hydrogen supplied to the first reactor based on the temperature of the first reactor to obtain the internal temperature of the device. It avoids a sharp rise in.

Japanese Patent No. 5802551

However, in the background art described above, although the temperature inside the apparatus is prevented from rising sharply, the reaction rate of the methanation reaction is sacrificed because the amount of hydrogen supplied to the first reactor is adjusted. Therefore, there has been a strong demand for the development of a temperature suppression technique for reducing the device temperature without lowering the reaction rate.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to reduce the temperature of an exothermic reaction without lowering the reaction rate.

In order to achieve the above-mentioned object, in the present invention, as a first solution means relating to a catalytic reaction device, there is provided a catalytic reaction device which exothermically reacts an input gas in the presence of a catalyst, wherein the catalyst is the input gas. A method is adopted in which the activity gradually increases in the inflow direction.

In the present invention, as a second means for solving a catalytic reaction device, in the first means for solving, a first catalyst having a relatively low activity is arranged on the upstream side in the inflow direction of the input gas and is activated on the downstream side. The second catalyst is arranged at a relatively high value.

In the present invention, as the third means for solving a catalytic reaction device, in the second means for solving, the first catalyst and the second catalyst have the same composition, and the first catalyst is more than the second catalyst. Also, the method that the concentration is low is adopted.

In the present invention, as a fourth solution means relating to the catalytic reaction device, in the second or third solution means, a plurality of reactions in which the input gas flows and the first catalyst and the second catalyst are filled The method of providing a tube is adopted.

In the present invention, as a fifth solution means for a catalytic reactor, in the above-mentioned fourth solution means, the reaction tube is housed in a predetermined shell and cooled by heat exchange with a refrigerant flowing in the shell. Will be adopted.

In the present invention, as a sixth solution means relating to a catalytic reaction device, in the fifth solution means, there is provided means for circulating the refrigerant so as to be a counterflow with respect to the input gas in the reaction tube. adopt.

In the present invention, as the seventh means for solving a catalytic reaction apparatus, in the means for solving any one of the above first to sixth means, the exothermic reaction is a methanation reaction.

According to the present invention, the temperature of exothermic reaction can be reduced without lowering the reaction rate.

It is a system block diagram which shows the structure of the gas production equipment in one Embodiment of this invention. FIG. 1 is a vertical sectional view (a) and a horizontal sectional view (b) showing a detailed configuration of a methanation reaction device according to an embodiment of the present invention. It is a characteristic view which shows the temperature distribution of the reaction tube in one Embodiment of this invention.

An embodiment of the present invention will be described below with reference to the drawings.
The gas production facility in the present embodiment is a plant that produces a gas containing methane (CH ₄ ) as a main component by using a methanation reaction, which is one of the exothermic reactions, and the methanation reaction according to the present embodiment. Equipped with a device.

That is, this gas production facility includes a shift reactor 1, a first steam generator 2, a desulfurization/decarbonation device 3, a temperature controller 4, a methanation reaction device 5, a circulation pump 6, a second steam generator 7 and a degasser. The carbon dioxide device 8 is provided, and the product gas X8 is produced from the raw material gas X1 supplied from the gasification furnace. Among these components, the methanation reaction device 5 is the catalytic reaction device according to the present invention.

Here, the gasification furnace is a source gas supply source that generates a source gas X1 containing hydrogen (H ₂ ) and carbon monoxide (CO) from, for example, coal or biomass as a source. For example, such a gasification furnace is equipped with a combustion furnace that generates heat and a gasification furnace that uses the heat of the combustion furnace to gasify the raw material.

The shift reactor 1 is a reactor that adjusts the molar ratio of the component gas in the raw material gas X1 by a shift reaction using water vapor X2. In the methanation reaction performed in the latter-stage methanation reaction device 5, hydrogen (H2) and carbon monoxide (CO) react at a molar ratio of 3:1. The shift reactor 1 is provided in front of the methanation reaction device 5 in view of such methanation reaction.

That is, the shift reactor 1 performs the shift reaction of the following reaction formula (1) on the raw material gas X1 in which the molar ratio of hydrogen (H ₂ ) and carbon monoxide (CO) is smaller than 3:1. Adjust the molar ratio to 3:1. The shift reactor 1 outputs to the first steam generator 2 the shift reaction gas X3 in which the molar ratio of hydrogen (H2) and carbon monoxide (CO) is adjusted to 3:1.
_{CO + H 2 O⇔H 2 + CO} 2 + Q1 ( amount of heat) (1)

The shift reaction is an exothermic reaction as shown in the reaction formula (1), and thus the shift reaction gas X3 is a heating gas obtained by heating the raw material gas X1. The first steam generator 2 is a steam generator that evaporates water using the heat of the shift reaction gas X3 that is such a heating gas. That is, the first steam generator 2 vaporizes water by heat exchange between the shift reaction gas X3 and water to generate steam X2. A part of the water vapor X2 is mixed with the raw material gas X1 in the front stage of the shift reactor 1, and the rest is mixed with the input gas X5 in the front stage of the methanation reaction device 5.

Here, the raw material gas X1 is derived from coal or biomass as described above, and thus contains sulfur (S) inevitably. Further, in the shift reaction described above, carbon dioxide (CO ₂ ) is produced in addition to the target hydrogen (H ₂ ). Therefore, the shift reaction gas X3 contains sulfur (S) and carbon dioxide (carbonic acid).

The desulfurization/decarbonation apparatus 3 removes sulfur (S) content and carbon dioxide (carbonic acid content) from such shift reaction gas X3 to generate a post-treatment gas X4. That is, the desulfurization/decarbonation apparatus 3 cools the shift reaction gas X3 to remove sulfur (S) and carbon dioxide (CO ₂ ) which is carbonic acid. The sulfur (S) content and the carbonic acid content are factors that hinder the promotion of the methanation reaction in the latter stage.

The methanation reaction is a thermodynamic equilibrium reaction, and the reaction rate depends on the reaction temperature. Therefore, in the methanation reaction, control of the reaction temperature is extremely important to maintain a desired reaction rate. From such a background, the temperature controller 4 generates the input gas X5 by heating the post-treatment gas X4. That is, the temperature controller 4 regulates the temperature of the input gas X5 by adjusting the heating amount of the post-treatment gas X4 in order to control the reaction rate of the methanation reaction performed in the methanation reaction device 5 in the subsequent stage. Set the target temperature of.

The methanation reaction device 5 is a catalytic reaction device that causes a methanation reaction (exothermic reaction) of the input gas X5 in the presence of a catalyst. The methanation reaction device 5 produces an output gas X6 by causing a methanation reaction of the input gas X5 flowing from the temperature controller 4, and outputs the output gas X6 to the decarbonation device 8. Further, the methanation reaction device 5 is cooled by the refrigerant X7 flowing from the outside.

FIG. 2 is a vertical sectional view (a) and a horizontal sectional view (b) showing a detailed configuration of such a methanation reaction device 5. The methanation reaction apparatus 5 is a so-called shell-and-tube type reactor, and as shown in FIGS. 2A and 2B, the shell 5a, the gas inlet 5b, the gas outlet 5c, and the refrigerant inlet 5d. , A refrigerant outlet port 5e, an inflow side partition plate 5f, an outflow side partition plate 5g, seven (plural) reaction tubes 5h, a first catalyst 5i and a second catalyst 5j.

The shell 5a is a substantially cylindrical container that forms the outer shell of the methanation reaction device 5, and is installed vertically with its central axis facing the vertical direction. The shell 5a accommodates the inflow side partition plate 5f, the outflow side partition plate 5g, the plurality of reaction tubes 5h, the first catalyst 5i, and the second catalyst 5j among the above-described components.

The gas inlet 5b is an opening that is provided at the center of the top of the shell 5a and into which the input gas X5 flows. The gas inlet 5b is connected to the temperature controller 4 through a predetermined pipe and receives the input gas X5 discharged from the temperature controller 4. The gas outlet 5c is an opening that is provided at the center of the bottom of the shell 5a and through which the output gas X6 flows out. The gas outlet 5c is connected to the carbon dioxide removal device 8 through a predetermined pipe and discharges the output gas X6 toward the carbon dioxide removal device 8.

The refrigerant inflow port 5d is an opening that is provided at a relatively lower portion on the side portion of the shell 5a and into which a predetermined refrigerant X7 flows. The refrigerant inflow port 5d is connected to the circulation pump 6 through a predetermined pipe and receives the refrigerant X7 discharged from the circulation pump 6. The refrigerant outlet port 5e is an opening provided in a relatively upper portion on the side portion of the shell 5a and through which the refrigerant X7 flows out. The refrigerant outlet port 5e is connected to the second steam generator 7 through a predetermined pipe and discharges the refrigerant X7 toward the second steam generator 7.

The inflow side partition plate 5f is a plate member which is inscribed relatively upward on the side portion of the shell 5a. The side portion of the shell 5a has a vertical cylindrical shape as illustrated. The inflow side partition plate 5f inscribed in the side portion of the shell 5a is a disc having seven openings, and the peripheral edge portion is hermetically connected to the inner surface of the side portion of the shell 5a. That is, the inflow side partition plate 5f is a disk provided in a substantially horizontal posture inside the shell 5a.

The outflow-side partition plate 5g is a plate member that is inscribed relatively downward on the side portion of the shell 5a. The outflow-side partition plate 5g is a disk having the same shape as the inflow-side partition plate 5f described above, and the peripheral edge portion is airtightly connected to the inner surface of the side portion of the shell 5a. That is, the outflow-side partition plate 5g is provided inside the shell 5a so as to face the inflow-side partition plate 5f in parallel with each other at a predetermined interval.

Here, the openings in the inflow side partition plate 5f and the outflow side partition plate 5g are formed corresponding to the plurality of reaction tubes 5h. That is, the openings of the inflow-side partition plate 5f and the outflow-side partition plate 5g are formed at equal intervals, and the shape corresponding to the shape of the reaction tube 5h and the number corresponding to the number of the reaction tubes 5h. Only formed.

The seven reaction tubes 5h are circular tubes and straight tubes having a predetermined inner diameter and provided in a substantially vertical posture between the inflow side partition plate 5f and the outflow side partition plate 5g. That is, the upper ends of the reaction tubes 5h are hermetically connected to one opening of the inflow side partition plate 5f, and the lower ends are airtightly connected to one opening of the outflow side partition plate 5g.

The first catalyst 5i and the second catalyst 5j are filled in the seven reaction tubes 5h, respectively, and promote the methanation reaction. The first catalyst 5i and the second catalyst 5j are obtained by supporting a predetermined amount of active metal (for example, nickel) on a predetermined granular carrier (for example, silica). That is, the first catalyst 5i and the second catalyst 5j have the same composition. In this embodiment, the volume ratio of the active metal to the granular carrier is referred to as "catalyst concentration".

The first catalyst 5i is a catalyst located upstream of the second catalyst 5j in the inflow direction of the input gas X5 in the reaction tube 5h and having a catalyst concentration lower than that of the second catalyst 5j. On the other hand, the second catalyst 5j is located downstream of the first catalyst 5i in the inflow direction of the input gas X5 and has a higher catalyst concentration than the first catalyst 5i.

That is, the performance (activity) of the first catalyst 5i located upstream in the reaction tube 5h as a catalyst is lower than that of the second catalyst 5j located downstream. In other words, the first catalyst 5i and the second catalyst 5j are arranged such that the activities thereof sequentially increase in the inflow direction of the input gas X5 in the reaction tube 5h. Among such first catalyst 5i and second catalyst 5j, the catalyst concentration of the first catalyst 5i is, for example, 30%, and the catalyst concentration of the second catalyst 5j is, for example, 50%.

Here, the internal space of the shell 5a is divided into two spaces by the inflow side partition plate 5f, the outflow side partition plate 5g, and the seven reaction tubes 5h. One of the spaces is a dust distribution space that communicates with the gas inlet 5b and the gas outlet 5c, and the input gas X5 and the output gas X6 circulate, and the other space communicates with the refrigerant inlet 5d and the refrigerant outlet 5e. And is a refrigerant circulation space in which the refrigerant X7 flows. The residue distribution space and the refrigerant distribution space are adjacent to each other so that heat can be exchanged as shown in the figure.

The circulation pump 6 is a power source for circulating the refrigerant X7 between the methanation reaction device 5 and the second steam generator 7. The circulation pump 6 collects the refrigerant X7 heated in the methanation reaction device 5 and supplies the refrigerant X7 to the second steam generator 7, and also supplies the refrigerant X7 cooled in the second steam generator 7 to the methanation reaction device. Supply to 5. The refrigerant X7 is, for example, petroleum oil.

The second steam generator 7 is a steam generator that generates steam X2 by exchanging heat between water and the refrigerant X7. That is, the second steam generator 7 uses the heat generated in the methanation reaction device 5 to generate steam X2, and supplies a part of the steam X2 to the front stage of the shift reactor 1 to supply the raw material gas X1. The mixture is mixed, and the rest is supplied to the preceding stage of the methanation reaction device 5 and mixed with the input gas X5. The second steam generator 7 is also a refrigerant cooler that cools the refrigerant X7 by exchanging heat with water.

Here, as described above, in the methanation reaction, methane (CH ₄ ) and water (H ₂ O) are produced from carbon monoxide (CO) and hydrogen (H ₂ ), but due to thermodynamic equilibrium , A shift reaction that is a coexisting condition of carbon dioxide (CO ₂ ) and carbon monoxide gas (CO) occurs, and carbon dioxide (CO ₂ ) and unreacted carbon monoxide (CO) are inevitably included in the output gas X6. Be done.

The decarbonation device 8 produces a product gas X8 by subjecting such output gas X6 to decarbonation. In other words, CO 2 removal unit 8 generates and outputs the product gas X8 removing carbon monoxide from the output gas X6 (CO) and carbon dioxide (CO ₂₎ to the outside of the demand end.

Next, the operation of the gas production facility thus configured, particularly the methanation reaction performed in the methanation reaction device 5, will be described in detail with reference to FIGS. 3 and 4.

In this gas production facility, the raw material gas X1 is mixed with the steam X2 and supplied to the shift reactor 1. In the shift reactor 1, the molar ratio of hydrogen (H ₂ ) and carbon monoxide (CO) contained in the raw material gas X1 is adjusted to 3:1 by the shift reaction using the steam X2, and desulfurization is performed as the shift reaction gas X3. -It is output to the carbon dioxide removal device 3.

The shift reaction gas X3 is heat-exchanged (indirect heat exchange) with water when passing through the first steam generator 2 provided between the shift reactor 1 and the desulfurization/decarbonation device 3. Generates water vapor X2. On the other hand, in the desulfurization/decarbonation apparatus 3, the sulfur (S) component and the carbonic acid component (carbon dioxide) contained in the shift reaction gas X3 are removed, and carbon monoxide (CO) and hydrogen (H ₂ ) And the treated gas X4 as components are output to the temperature controller 4.

The post-treatment gas X4 is adjusted to a temperature optimized for the methanation reaction by the temperature controller 4, and is output to the methanation reaction device 5 as the input gas X5. This input gas X5 is mixed with water vapor X2 on the way and is input to the methanation reaction device 5. Then, in the methanation reaction device 5, while carbon deposition on the methanation catalyst is suppressed by the action of the water vapor X2, methane (CH ₂ ) is converted from carbon monoxide (CO) and hydrogen (H ₂ ) contained in the input gas X5. ₄ ) and water (H ₂ O) are produced.

Then, the output gas X6 containing methane (CH ₄ ) and water (H ₂ O) as main components is output to the decarbonation device 8. In the decarbonator 8, carbon dioxide (carbon monoxide and carbon dioxide) is removed from the output gas X6 to generate a product gas X8. Then, the product gas X8 is supplied to the customer as a combustible gas containing methane (CH ₄ ) as a main component.

The abnormality is the overall operation of the gas production facility, but in the methanation reaction device 5, heat is generated by the methanation reaction, which is an exothermic reaction. That is, an exothermic reaction represented by the following formula (2) occurs in each reaction tube 5h.
CO+3H ₂ ⇔ CH ₄ +H ₂ O+Q2 (heat quantity) (2)
In order to maintain the methanation reaction, which is thermodynamic equilibrium, at a desired reaction rate in each reaction tube 5h, it is extremely important to remove heat in each reaction tube 5h of the methanation reaction apparatus 5.

From such a background, in the methanation reaction device 5, the heat of the methanation reaction is transferred to the refrigerant X7 flowing in the refrigerant flow space around each reaction tube 5h, whereby the reaction field in the reaction tube 5h, that is, the first Areas near the catalyst 5i and the second catalyst 5j are cooled. In this heat transfer, the circulation direction of the refrigerant X7 flowing in the coolant circulation space is opposite to the circulation direction of the input gas X5 and the output gas X6 flowing in each reaction tube 5h, that is, the circulation direction of the refrigerant X7 is the input gas X5. Also, since it is a counter flow with respect to the flow direction of the output gas X6, it is effectively performed.

Further, in this methanation reaction device 5, since the relatively low activity first catalyst 5i is arranged on the upstream side in the reaction tube 5h, and the relatively high activity second catalyst 5j is arranged on the downstream side, It is possible to reduce the maximum temperature of the reaction tube 5h while maintaining the conversion rate (CO conversion rate) of the methanation reaction at the target conversion rate.

That is, since the target conversion rate was conventionally achieved by using a single type of nickel catalyst, the temperature on the most upstream side of the catalyst in the flow direction of the input gas in the reaction tube is the highest temperature. , The first catalyst 5i having relatively low activity is arranged on the upstream side in the flow direction of the input gas X5, and the second catalyst 5j having relatively high activity is arranged on the downstream side, thereby achieving the target conversion rate. It is possible to suppress the generation of heat in the first catalyst 5i.

FIG. 3 is a characteristic diagram showing the temperature distribution of the reaction tube 5h in this embodiment. In addition, in FIG. 3, the graph shown by a square is a graph when the catalyst concentration of the first catalyst 5i is 30%, the catalyst concentration of the second catalyst 5j is 50%, and the flow rate of the input gas X5 is 15000 h ^−1. It is a temperature distribution. The maximum temperature in this case is about 460°C. Further, a graph indicated by triangles is a comparative example, and is a temperature distribution when a single type nickel catalyst having a catalyst concentration of 50% is used. The CO conversion rate in each case was 99%. The maximum temperature in this case is slightly less than 490°C.

As can be seen from such a characteristic diagram, according to the present embodiment, it is possible to reduce the maximum temperature of the reaction tube 5h that performs the methanation reaction (exothermic reaction) without lowering the reaction rate (CO conversion rate). It is possible. For example, as shown in FIG. 3, the maximum temperature is close to 490° C. when a single type of nickel catalyst having a catalyst concentration of 50% is used, but the catalyst concentration of the first catalyst 5i is 30% and the second catalyst 5j is The maximum temperature when the catalyst concentration is 50% is reduced to near 460°C.

The present invention is not limited to the above-described embodiment, and the following modifications are conceivable, for example.
(1) In the above embodiment, the methanation reaction, which is a kind of exothermic reaction, has been described, but the present invention is not limited to this. The present invention can be applied to various exothermic reactions other than the methanation reaction.

(2) In the above embodiment, the catalyst activity is changed in two stages in the inflow direction of the first catalyst 5i and the second catalyst 5j, that is, the input gas X5, but the present invention is not limited to this. For example, in order to change the catalyst activity in three stages, a third catalyst having a higher catalyst concentration than the second catalyst 5j may be provided in addition to the first catalyst 5i and the second catalyst 5j.

(3) In the above embodiment, the first catalyst 5i and the second catalyst 5j having different catalyst concentrations are adopted, but the present invention is not limited to this. As a method of making the catalyst activity different between the first catalyst and the second catalyst, for example, instead of the catalyst concentration, the composition of the active metal may be made different between the first catalyst and the second catalyst.

(4) In the above embodiment, the configuration of the gas production facility shown in FIG. 1 was adopted, but the present invention is not limited to this. Various configurations, which are not limited to the configuration of FIG. 1, are conceivable for the configuration of plant equipment including the catalytic reaction device according to the present invention as a component.

1 shift reactor 2 first steam generator 3 desulfurization/decarbonation device 4 temperature controller 5 methanation reactor (catalytic reactor)
5a Shell 5b Gas inlet 5c Gas outlet 5d Refrigerant inlet 5e Refrigerant outlet 5f Inflow side partition plate 5g Outflow side partition plate 5h Reaction tube 5i First catalyst 5j Second catalyst 6 Circulation pump 7 Second steam generator 8 Desorption Carbon dioxide device X1 Raw material gas X2 Steam X3 Shift reaction gas X4 Processed gas X5 Input gas X6 Output gas X7 Refrigerant X8 Product gas

Claims (7)

A catalytic reaction device for exothermically reacting an input gas in the presence of a catalyst,
The catalytic reaction device is characterized in that the activity of the catalyst gradually increases in the inflow direction of the input gas. The catalytic reaction device according to claim 1, wherein a first catalyst having a relatively low activity is arranged on the upstream side in the inflow direction of the input gas, and a second catalyst having a relatively high activity is arranged on the downstream side. .. The catalytic reaction device according to claim 2, wherein the first catalyst and the second catalyst have the same composition, and the concentration of the first catalyst is lower than that of the second catalyst. The catalytic reaction device according to claim 2 or 3, further comprising a plurality of reaction tubes into which the input gas flows and which are filled with the first catalyst and the second catalyst. The catalytic reaction device according to claim 4, wherein the reaction tube is housed in a predetermined shell and cooled by heat exchange with a refrigerant flowing in the shell. The catalytic reaction device according to claim 5, wherein the refrigerant flows so as to be a counterflow with respect to the input gas in the reaction tube. 7. The catalytic reaction device according to claim 1, wherein the exothermic reaction is a methanation reaction.

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