Pyrolysis controller and pyrolysis control system

Abstract

To provide a pyrolysis controller capable of suppressing a reduction in the amount of a catalyst that effectively acts in a reactor.SOLUTION: A pyrolysis controller is configured to control a reactor for pyrolyzing hydrocarbons into hydrogen and carbon and to execute a height variable acquisition processing and a replenishment processing. A catalyst replenishment device is connected to the reactor. The pyrolysis controller is configured to execute the height variable acquisition processing and the replenishment processing. The height variable acquisition processing acquires the value of the height variable. The height variable is a variable indicating the height of the catalyst. The replenishment processing replenishes the catalyst to the reactor by operating the replenishment device according to the value of the height variable.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pyrolysis control device and a pyrolysis control system. [Background technology]

[0002] For example, Patent Document 1 listed below describes an apparatus that extracts hydrogen by thermally decomposing a hydrocarbon gas such as methane via a catalyst. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-24997 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when hydrogen production by thermal decomposition is continued, the amount of catalyst that effectively acts in the reactor gradually decreases, and the amount of hydrogen produced decreases. [Means for solving the problem]

[0005] Means for solving the above problems and their effects will be described below. 1. A thermal decomposition control device that controls a reactor that thermally decomposes hydrocarbons into hydrogen and carbon, the reactor being connected to a catalyst replenishment device and configured to execute a height variable acquisition process and a replenishment process, the height variable acquisition process being a process of acquiring a value of a height variable, the height variable being a variable indicating the height of the catalyst in the catalyst, and the replenishment process being a process of replenishment of the catalyst to the reactor by operating the replenishment device in accordance with the value of the height variable.

[0006] In the above-mentioned configuration, the catalyst is replenished by the replenishing device according to the height of the catalyst in the reactor, so that the amount of catalyst that effectively acts in the reactor can be prevented from decreasing. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a configuration of a pyrolysis control system according to a first embodiment. [Diagram 2] FIG. 2 is a graph showing the relationship between the particle size and superficial velocity of a catalyst in a reactor and the state of the catalyst. [Diagram 3] FIG. 13 is a graph showing the relationship between methane concentration and hydrogen concentration and the height of the catalyst. [Figure 4] 4 is a flowchart showing a procedure of a process executed by a control device according to the first embodiment. [Diagram 5] FIG. 11 is a diagram showing the configuration of a pyrolysis control system according to a second embodiment. [Figure 6] 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 7] FIG. 13 is a diagram showing the configuration of a pyrolysis control system according to a third embodiment. [Figure 8] FIG. 4 is a diagram illustrating the setting of the reaction rate constant and the temperature of methane in the height direction of the catalyst according to the embodiment. [Figure 9] 4 is a flowchart showing a procedure of a process executed by a control device according to the embodiment. [Figure 10] FIG. 13 is a diagram showing the effect of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <First embodiment> Hereinafter, the first embodiment will be described with reference to the drawings. "Configuration of pyrolysis control system" As shown in Fig. 1, methane supplied to the pyrolysis control system is compressed by a compressor 10. The methane compressed by the compressor 10 is heated by a heating device 12. The methane heated by the heating device 12 is supplied to a reactor 20.

[0009] The temperature of the methane at the inlet 22 of the reactor 20 may be, for example, 900 to 1000° C. The pressure inside the reactor 20 may be, for example, several ata to several tens of ata. The reactor 20 is filled with a catalyst 32. The catalyst 32 is iron. The reactor 20 is provided with an inlet 24. The inlet 24 is connected to a replenishing device 30. The replenishing device 30 is a device that supplies the catalyst 32 to the reactor 20. When the catalyst 32 is stored under atmospheric pressure, it is desirable that the replenishing device 30 includes a device that temporarily pressurizes a predetermined space connected to the reactor 20 to a pressure equivalent to the pressure inside the reactor 20. This can be achieved, for example, by including a lock hopper or the like.

[0010] In the reactor 20, methane is pyrolyzed into hydrogen and carbon. The pyrolyzed hydrogen, carbon, and methane exit through an outlet 26. In Fig. 1, the z-axis direction is parallel to the direction in which gravity acts. In particular, in Fig. 1, the direction opposite to the direction of gravity is the positive direction of the z-axis. That is, the inlet 22 is provided below the reactor 20, and the outlet 26 is provided above the reactor 20.

[0011] The pyrolysis control device 40 controls the state of the reactor 20. The pyrolysis control device 40 operates the compressor 10, the heating device 12, and the refilling device 30 to control the controlled objects. In FIG. 1, the operation signals for the compressor 10, the heating device 12, and the refilling device 30 are respectively indicated as MS1 to MS3. The pyrolysis control device 40 refers to the inlet pressure Pi detected by the inlet pressure sensor 50 to control the controlled objects. The pyrolysis control device 40 also refers to the inlet temperature Ti detected by the inlet temperature sensor 52 to control the controlled objects. The pyrolysis control device 40 refers to the outlet pressure Po detected by the outlet pressure sensor 54 to control the controlled objects. The pyrolysis control device 40 refers to the outlet temperature To detected by the outlet temperature sensor 56 to control the controlled objects.

[0012] The pyrolysis control device 40 includes a PU 42 and a memory device 44. The PU 42 is a software processing device including at least one of a CPU, a GPU, a TPU, etc. The memory device 44 stores a program that specifies instructions for controlling the pyrolysis of methane.

[0013] "Catalyst Settings" The PU 42 controls the catalyst 32 in the reactor 20 so that it is in a fluidized bed state. FIG. 2 shows the relationship between the particle size and superficial velocity of the catalyst 32 and the state of the catalyst 32. Here, the superficial velocity is the volumetric flow rate of methane, which is the target gas, divided by the bed area of ​​the reactor 20. The bed area is the cross-sectional area of ​​the reactor 20 in a plane perpendicular to the z-axis. The fluidization velocity is the minimum velocity at which the catalyst 32 becomes a fluidized bed. The terminal velocity is the maximum velocity at which the catalyst 32 becomes a fluidized bed. In FIG. 2, the region where the catalyst 32 becomes a fluidized bed is expressed by dots. As shown in FIG. 2, even if the superficial velocity u0 is determined, whether or not the catalyst 32 becomes a fluidized bed is determined depending on the particle diameter of the catalyst 32.

[0014] 3 shows the relationship between the height L of the catalyst 32 in the reactor 20, the partial pressure of methane [CH4], the partial pressure of hydrogen "H2", and the rate of change of the partial pressure of methane. The height L of the catalyst 32 shown on the horizontal axis of FIG. 3 is the maximum position of the catalyst 32 in the z-axis direction shown in FIG. 1. However, in the case of a fluidized bed, since the catalyst 32 does not have a clear interface, the maximum position is, for example, the maximum position where the concentration of the catalyst 32 is equal to or greater than a predetermined value. The height L may be not only the height of the catalyst 32, but also the height of solid particles containing carbon produced by pyrolysis.

[0015] As shown in FIG. 3, when the height L of the catalyst 32 is sufficiently high, the partial pressure of hydrogen increases. In other words, the concentration of hydrogen increases. This is because the higher the height of the catalyst 32, the longer the time Δt for the thermal decomposition reaction. In other words, the conversion rate α, which is the value obtained by inverting the sign of the ratio of the change in the partial pressure of methane after passing through the catalyst 32 to the partial pressure of methane flowing into the reactor 20, is proportional to the time Δt. Incidentally, since the change in the partial pressure of methane is negative, the conversion rate α is positive and increases as the amount of methane reduction increases.

[0016] Therefore, in this embodiment, the height L is controlled to a sufficiently high value. However, the height L varies greatly. In FIG. 3, the amount of variation in the height L is indicated by double-headed arrows centered on the heights La, Lb, and Lc. Therefore, it is difficult to measure the height L directly.

[0017] Therefore, in this embodiment, the differential pressure ΔP, which is the amount of decrease in the outlet pressure Po relative to the inlet pressure Pi of the reactor 20, is used as a variable indicating the height. This is in consideration of the fact that the differential pressure ΔP is proportional to the value obtained by dividing the total weight of the catalyst 32 by the bed area of ​​the reactor 20, regardless of the superficial velocity. Since the total weight of the catalyst 32 is proportional to the average value of the height L, the differential pressure ΔP is proportional to the average value of the height.

[0018] "Catalyst 32 Refill" In the reactor 20, the particle diameter of the iron particles gradually decreases. Therefore, even if the state of a fluidized bed can be maintained initially at the superficial velocity u0 shown in FIG. 2, when the particle diameter decreases, the particles are discharged from the outlet 26 to the outside of the reactor 20. That is, when the particle diameter decreases, the superficial velocity u0 becomes larger than the terminal velocity, and the particles with the reduced particle diameter are discharged from the outlet 26 to the outside of the reactor 20. Therefore, in this embodiment, a process of replenishing the catalyst 32 is performed by the replenishing device 30.

[0019] Fig. 4 shows the procedure of the process related to replenishing the catalyst 32. The process shown in Fig. 4 is realized by the PU 42 repeatedly executing the program stored in the storage device 44, for example, at a predetermined interval. In the following, the step number of each process is represented by a number preceded by "S."

[0020] In the series of processes shown in FIG. 4, the PU 42 first acquires the inlet pressure Pi (S10). The PU 42 also acquires the outlet pressure Po (S12). The PU 42 then acquires the differential pressure ΔP by substituting a value obtained by subtracting the outlet pressure Po from the inlet pressure Pi into the differential pressure ΔP (S14). Next, the PU 42 determines whether the differential pressure ΔP is smaller than a threshold value ΔPth (S16). The threshold value ΔPth is set to be equal to or smaller than the allowable lower limit value of the height L. The allowable lower limit value is determined according to the differential pressure ΔP corresponding to the height of the catalyst 32 at which the change in the conversion rate of methane is negligible even if the height of the catalyst 32 changes. Here, when a value smaller than this corresponding differential pressure ΔP by a predetermined margin is set as the allowable lower limit value, the allowable lower limit value may be, for example, a value smaller by a predetermined amount than the height Lc shown in FIG. 3. However, the allowable lower limit value may be a value larger than the corresponding differential pressure ΔP by a predetermined margin.

[0021] When the PU 42 determines that the pressure difference ΔP is smaller than the threshold ΔPth (S16: YES), the PU 42 assigns the value obtained by subtracting the pressure difference ΔP from the threshold ΔPth and multiplying the result by the proportional gain Kf to the replenishment amount QFe (S18). Then, the PU 42 outputs an operation signal MS3 to the replenishment device 30 to replenish the catalyst 32 of the replenishment amount QFe to the reactor 20 (S20).

[0022] When the process of S20 is completed or when a negative determination is made in the process of S16, the PU 42 temporarily ends the series of processes shown in FIG. "Actions and Effects of the Present Embodiment" The PU 42 replenishes the catalyst 32 to the reactor 20 by appropriately operating the replenishing device 30 to control the amount of the catalyst 32 in the reactor 20. This makes it possible to prevent a situation in which the catalyst is insufficient for the amount of methane supplied to the reactor 20. Therefore, hydrogen can be produced stably.

[0023] According to the present embodiment described above, the following actions and effects can be obtained. (1-1) The PU 42 controls the amount of catalyst 32 in the reactor 20 to an amount that causes a negligible change in methane conversion rate even if the height of the catalyst 32 changes. This makes it possible to stably produce hydrogen while increasing the conversion rate.

[0024] (1-2) The PU 42 grasped the amount of the catalyst 32 in the reactor 20 by the differential pressure ΔP. This makes it easier to grasp the amount of the catalyst 32 than by grasping the maximum position of the catalyst 32 in the z-axis direction in the reactor 20.

[0025] (1-3) A heating device 12 is provided for heating methane before the methane is supplied to the reactor 20. This makes it easy to control the temperature of the methane in the reactor 20 to a temperature appropriate for thermal decomposition.

[0026] That is, when the methane in the reactor 20 is heated from the inner wall surface of the reactor 20 instead of using the heating device 12, the methane to be heated is methane that is present in a position close to the inner wall surface of the reactor 20. Therefore, the temperature of the methane in the reactor 20 is likely to be uneven. Furthermore, when the reactor 20 is made of steel or the like, if the temperature of the inner wall surface is made as high as possible in order to provide sufficient heat to the methane, localized high-temperature areas may be generated, which may cause deterioration of the reactor 20.

[0027] <Second embodiment> The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0028] A pyrolysis control system according to this embodiment is shown in Fig. 5. In Fig. 5, the members corresponding to those shown in Fig. 1 are denoted by the same reference numerals for convenience. As shown in FIG. 5, in this embodiment, a heating device 60 for heating the inside of the reactor 20 is provided.

[0029] The amount of hydrogen generated is proportional to the time Δt for the thermal decomposition reaction and the reaction rate v1. The reaction rate v1 is proportional to the product of the reaction rate constant k expressed as follows and a certain power of the partial pressure of methane.

[0030] k=A·exp{-Ea / (R·T)} Here, we use the proportionality constant A, the gas constant R, the temperature of methane T, and the activation energy Ea.

[0031] As described above, the reaction rate constant k increases as the temperature T increases. Therefore, the amount of hydrogen generated can be increased by supplementing the thermal energy lost in the reactor 20 due to the thermal decomposition of methane from the outside.

[0032] Fig. 6 shows a procedure of a process related to heating the reactor 20. The process shown in Fig. 6 is realized by the PU 42 repeatedly executing a program stored in the storage device 44, for example, at a predetermined period.

[0033] In the series of processes shown in Fig. 6, the PU 42 first acquires the inlet temperature Ti (S30). The PU 42 also acquires the outlet temperature To (S32). The PU 42 then multiplies the value obtained by subtracting the outlet temperature To from the inlet temperature Ti by a proportionality coefficient Kq, and assigns the result to the amount of heat ΔQ per unit time (S34). Next, the PU 42 outputs an operation signal MS4 to the heating device 60 so that the heating device 60 provides the amount of heat ΔQ to the reactor 20 (S36).

[0034] When the PU 42 completes the process of S36, the PU 42 temporarily ends the series of processes shown in FIG. According to the present embodiment described above, in addition to the above-mentioned advantageous effects of the first embodiment, the following advantageous effects can be obtained.

[0035] (2-1) The PU 42 controlled the amount of heat generated by the heating device 60 so that the outlet temperature To approached the inlet temperature Ti. This allows the heating device 60 to compensate for the amount of heat lost by thermal decomposition. Therefore, it is possible to prevent the temperature of methane in the reactor 20 from decreasing excessively. Therefore, it is possible to keep the reaction rate of methane high. Therefore, it is possible to increase the conversion rate of methane.

[0036] (2-2) The amount of heat lost by pyrolysis was determined by the amount of decrease in the outlet temperature To relative to the inlet temperature Ti. This allows the amount of heat lost to be easily determined. On the other hand, when calculating the amount of heat entering the reactor 20 and the amount of heat lost by pyrolysis, it is necessary to take into account the amount of heat caused by the inflow of iron by the replenishing device 30, and so on, making it difficult to accurately determine the amount of heat.

[0037] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0038] A pyrolysis control system according to this embodiment is shown in Fig. 7. In Fig. 7, the members corresponding to those shown in Fig. 1 are denoted by the same reference numerals for convenience. As shown in Fig. 7, this embodiment includes five reactors 20(1), 20(2), 20(3), 20(4), and 20(5). The reactors 20(1), 20(2), 20(3), 20(4), and 20(5) are connected in series to each other. That is, when "i = 1 to 4", the outlet 26 of the reactor 20(i) is connected to the inlet 22 of the reactor 20(i+1).

[0039] Furthermore, for "j=1 to 5," a material heated by a heating device 12(j) is supplied to the inlet 22 of the reactor 20(j). Therefore, the outlet 26 of the reactor 20(i) is connected to the inlet 22 of the reactor 20(i+1) via the heating device 12(i+1).

[0040] Furthermore, each reactor (j) is provided with a refill device 30(j). In the following, the reactors 20(1) to 20(5) will be collectively referred to as the reactor 20.

[0041] FIG. 8 shows the catalyst 32 in the reactor 20. The height L of the solid particles including the catalyst 32 in the stationary state according to the present embodiment is controlled to be equal to or smaller than the representative diameter D. The representative diameter D is twice the square root of the value obtained by dividing the bed area by pi. This is set in consideration of the fact that when the height L is large relative to the representative diameter D, poor fluidity occurs, causing large pressure fluctuations in the reactor 20. The height L in the stationary state means the height when the catalyst 32 is not in a fluidized bed state and is stationary. This may be the height of the solid particles realized by stopping the process of supplying methane from the inlet 22. The height L of the solid particles defined using the representative diameter D is desirably the height of the solid particles including the catalyst 32 and carbon generated by the thermal decomposition of methane.

[0042] However, this height L corresponds to the region equal to or smaller than the height Lb shown in Fig. 3. Therefore, the amount of hydrogen generated is likely to vary depending on the variation in the height L. Therefore, in this embodiment, the temperature T of methane is set to decrease more significantly as the value in the z-axis direction in the reactor 20 increases.

[0043] 8, the reaction rate constant k is sufficiently small near the height L. Therefore, even if the height L varies, the amount of hydrogen generated in the reactor 20 can be stabilized.

[0044] Furthermore, in this embodiment, in order to reliably stabilize the amount of hydrogen produced in reactor 20(j), feedback control is performed in which the outlet temperature To(j) from reactor 20(j) is the outlet temperature of reactor 20(j) detected by outlet temperature sensor 56(j).

[0045] The procedure of the feedback control is shown in Fig. 9. The process shown in Fig. 9 is realized by the PU 42 repeatedly executing a program stored in the storage device 44, for example, at a predetermined interval.

[0046] In the series of processes shown in FIG. 9, the PU 42 first acquires the outlet temperature To(j) (S40). Next, the PU 42 substitutes the manipulated variable of the feedback control, in which the outlet temperature To(j) is the controlled variable and the target outlet temperature To* is the target value of the controlled variable, into the heating amount ΔQ(j) (S42). In this embodiment, as an example, the target outlet temperature To* is the same for all of the outlet temperatures To(1) to To(5). The target outlet temperature To* is set to a value that makes the reaction rate constant k in the most downstream region of the catalyst in the reactor 20(j) sufficiently small. In this embodiment, as an example, the output value of a proportional element, the input of which is the difference between the target outlet temperature To* and the outlet temperature To(j), is used as the manipulated variable.

[0047] Then, PU42 outputs an operation signal MS2(j) to heating device 12(j) to apply the heat amount ΔQ (S44). When the PU 42 completes the process of S44, the PU 42 temporarily ends the series of processes shown in FIG.

[0048] According to the above settings, the methane conversion rate in one reactor 20 is not high. However, by connecting the reactors 20 in series, the methane conversion rate can be increased. The upper part of FIG. 10 shows the temperature (gas temperature) of the gas flowing in and out of reactor 20. In the lower part of FIG. 10, circles indicate the flow rate of methane. Also, in the lower part of FIG. 10, diamonds indicate the amount of hydrogen generated. Also, in the lower part of FIG. 10, triangles indicate the methane conversion rate. The horizontal axis of FIG. 10 is the position in the x-axis direction of FIG. 7. In particular, the center of the position of reactor 20(j) in the x-axis direction is marked as "20(j)," and the center of the position of heating device 12(j) is marked as "12(j)."

[0049] As shown in Figure 10, the methane conversion in one reactor 20 is small compared to the value at chemical equilibrium, but downstream in the system the methane conversion reaches the value at chemical equilibrium.

[0050] FIG. 10 illustrates an example in which the inlet temperature of reactor 20(5) is lower than the inlet temperatures of reactors 20(1)-20(4). This is because the amount of hydrogen generated in reactor 20(5) is small. That is, in this case, the amount of heat removed by the pyrolysis reaction is small, so the outlet temperature To(5) is likely to rise. Therefore, the amount of heat generated by heating device 12(5) is reduced, and the inlet temperature of reactor 20(5) also becomes lower.

[0051] According to the present embodiment described above, in addition to the effects equivalent to those of (1-2) and (1-3) of the first embodiment, the following effects can be obtained. (3-1) The PU 42 controls the height L of the catalyst 32 to be equal to or smaller than the characteristic diameter D. This makes it possible to suppress the pressure fluctuation in the reactor 20 from increasing due to poor flow.

[0052] (3-2) The PU 42 is controlled so that the reaction rate constant k near the highest position of the catalyst 32 is sufficiently small. This makes it possible to suppress the fluctuation in the amount of hydrogen generated due to the fluctuation in the height L of the catalyst 32 to a negligible level. Therefore, the amount of hydrogen generated can be stabilized.

[0053] (3-3) A plurality of reactors 20 are connected in series. As a result, although the methane conversion rate in a single reactor 20 is low, the conversion rate of the entire reactors 20 can be increased to the conversion rate in a chemical equilibrium state.

[0054] (3-4) The PU 42 executed the feedback control with the outlet temperature To(j) as the controlled variable, thereby making it possible to reliably lower the outlet temperature To(j) of the reactor 20(j).

[0055] <Correspondence> The correspondence between the items in the above embodiment and the items described in the "Notes" column below is as follows. In the following, the correspondence is shown for each number of the solution means described in the "Notes" column. [1] The height variable acquisition process corresponds to the process of S14. The height variable corresponds to the differential pressure ΔP. The refill process corresponds to the processes of S16 to S20. [2] It corresponds to the processes of S16 and S18. [3] The heating device corresponds to the heating device 12. [4] It corresponds to FIG. 8. [5] The feedback process corresponds to the processes of S42 and S44. [6] It corresponds to FIG. 7. The upstream reactor and the downstream reactor correspond to the reactor 20(1) and the reactor 20(2), the reactor 20(2) and the reactor 20(3), the reactor 20(3) and the reactor 20(4), or the reactor 20(4) and the reactor 20(5). The upstream heating device and the downstream heating device correspond to heating device 12(1) and heating device 12(2), heating device 12(2) and heating device 12(3), heating device 12(3) and heating device 12(4), or heating device 12(4) and heating device 12(5). [7] The internal heating device corresponds to heating device 60. The outlet temperature acquisition process corresponds to the process of S32. The temperature control process corresponds to the processes of S34 and S36.

[0056] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0057] "About height variable acquisition process" The differential pressure ΔP does not necessarily have to be a value calculated using the inlet pressure Pi and the outlet pressure Po. For example, a detection value of a differential pressure sensor may be used.

[0058] The height variable does not necessarily have to be a variable indicating the amount of decrease in the outlet pressure Po relative to the inlet pressure Pi. For example, a camera that takes pictures of the inside of the reactor 20 may be provided, and the height of the catalyst 32 may be calculated by the PU 42 using the image from the camera as an input. Here, the PU 42 may calculate the height by calculating the height at which the concentration of the catalyst 32 becomes equal to or lower than a predetermined value, and averaging the time series data of the same height.

[0059] "About the heating device" 1, the heating device 60 may be provided without providing the heating device 12. Also, for example, in FIG. 1, both the heating device 12 and the heating device 60 may be provided.

[0060] In FIG. 5, the heating device 12 does not have to be provided. In FIG. 7, in addition to the heating device 12, a heating device 60 may be provided. "About setting the representative diameter" In the pyrolysis control system shown in FIG. 1, it is not essential that the height L is greater than the representative diameter D. For example, the height L may be equal to the representative diameter D.

[0061] In the pyrolysis control system shown in Fig. 5, it is not essential that the height L is greater than the representative diameter D. For example, the height L may be equal to the representative diameter D. In Fig. 8, the height L of the solid particles in a stationary state is set to be equal to or less than the representative diameter D, but this is not limited to this. However, in order to stabilize the amount of hydrogen generated, it is preferable that "L / D" be 2 or less. Furthermore, in order to stabilize the amount of hydrogen generated, it is more preferable that "L / D" be 1.5 or less.

[0062] About the Replenishment Process In FIG. 4, the process of determining the refill amount QFe by proportional control is illustrated, but the present invention is not limited thereto. For example, the process may be a process of determining the refill amount QFe as the sum of the output value of the proportional element and the output value of the integral element corresponding to the value obtained by subtracting the differential pressure ΔP from the threshold value ΔPth. For example, the process may be a process of determining the refill amount QFe as the sum of the output value of the proportional element, the output value of the integral element, and the output value of the differential element corresponding to the value obtained by subtracting the differential pressure ΔP from the threshold value ΔPth. For example, the process may be a process of determining the refill amount QFe as the sum of the output value of the proportional element and the output value of the differential element corresponding to the value obtained by subtracting the differential pressure ΔP from the threshold value ΔPth. For example, each time a positive determination is made in the process of S16, the PU 42 may refill the catalyst 32 to the reactor 20 by setting a predetermined amount as the refill amount QFe.

[0063] The replenishing process does not necessarily have to be a process of replenishing the catalyst 32 to the reactor 20 by determining the replenishing amount QFe. For example, it may be a process of controlling the replenishing device 30 and the reactor 20 to be in a communication state for a predetermined time. Here, the predetermined time may be a fixed time that is determined in advance. Also, the predetermined time may be changed according to the differential pressure ΔP.

[0064] The replenishment process does not necessarily have to be a process for compensating for the amount of catalyst 32 that has been atomized and discharged from the outlet 26. For example, the PU 42 may intentionally execute a process for discharging the catalyst 32 in the reactor 20 from the reactor 20, while also executing a replenishment process to compensate for the amount that has been discharged. This allows a catalyst whose function of promoting thermal decomposition has deteriorated to be intentionally replaced with new catalyst through control.

[0065] "About feedback processing" The manipulated variable of feedback control in which the outlet temperature To(i) is the controlled variable is not limited to the output value of a proportional element. The manipulated variable may be, for example, the sum of the output value of a proportional element and the output value of an integral element corresponding to the difference between the outlet temperature To(i) and the target outlet temperature To*. Alternatively, the manipulated variable may be, for example, the sum of the output value of a proportional element, the output value of an integral element, and the output value of a derivative element corresponding to the difference between the outlet temperature To(i) and the target outlet temperature To*. Alternatively, the manipulated variable may be, for example, the sum of the output value of a proportional element and the output value of a derivative element corresponding to the difference between the outlet temperature To(i) and the target outlet temperature To*.

[0066] "Temperature control processing" 6 illustrates an example of feedback control in which the outlet temperature To is the controlled variable and the target value of the controlled variable is the inlet temperature Ti, but this is not limiting. For example, the target value of the controlled variable may be a value lower than the inlet temperature Ti by a predetermined amount.

[0067] The manipulated variable of the feedback control in which the outlet temperature To is the controlled variable is not limited to the output value of a proportional element. For example, the manipulated variable of the feedback control may be the sum of the output value of a proportional element and the output value of an integral element. For another example, the manipulated variable of the feedback control may be the sum of the output value of a proportional element, the output value of an integral element, and the output value of a differential element. For another example, the manipulated variable of the feedback control may be the sum of the output value of a proportional element and the output value of a differential element.

[0068] The temperature control process for operating the heating device 60 with the outlet temperature To as a controlled variable does not assume the pyrolysis control system illustrated in Fig. 5. For example, as described above in "Regarding the heating device," the pyrolysis control system illustrated in Fig. 7 may be equipped with the heating device 60. In that case, if the aim is to stabilize the amount of hydrogen generated, it is desirable to set the target value of the controlled variable sufficiently lower than the inlet temperature Ti.

[0069] "Pyrolysis control system" 7 shows an example in which five reactors 20 are connected in series, but the present invention is not limited to this. For example, two to four reactors 20, or six or more reactors 20 may be connected in series.

[0070] In Fig. 7, a heating device 12 is provided for each reactor 20, but this is not limited to the above. For example, in the example shown in Fig. 7, heating devices 12(1), 12(3), and 12(5) may be provided, but heating devices 12(2) and 12(4) may not be provided. In that case, however, it is desirable to provide heating device 60 for reactors 20(1), 20(3), etc.

[0071] Adjacent reactors may be connected via a compressor. "About Hydrocarbons" The hydrocarbon to be thermally decomposed into hydrogen and carbon is not limited to methane. For example, it may be propane.

[0072] "About pyrolysis control devices" The pyrolysis control device is not limited to a device that executes software processing. For example, it may be equipped with a dedicated hardware circuit such as an ASIC that executes at least a part of the processing executed in the above embodiment. That is, the pyrolysis control device may include a processing circuit having any of the following configurations (a) to (c). (a) A processing circuit having a processing device that executes all of the above processing according to a program, and a program storage device such as a memory device that stores the program. (b) A processing circuit having a processing device and a program storage device that executes part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit having a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices equipped with a processing device and a program storage device. Also, there may be multiple dedicated hardware circuits.

[0073] <Additional Notes> 1. A thermal decomposition control device that controls a reactor that thermally decomposes hydrocarbons into hydrogen and carbon, the reactor being connected to a catalyst replenishment device and configured to execute a height variable acquisition process and a replenishment process, the height variable acquisition process being a process of acquiring a value of a height variable, the height variable being a variable indicating the height of the catalyst in the catalyst, and the replenishment process being a process of replenishment of the catalyst to the reactor by operating the replenishment device in accordance with the value of the height variable.

[0074] In the above-mentioned configuration, the catalyst is replenished by the replenishing device according to the height of the catalyst in the reactor, so that the amount of catalyst that effectively acts in the reactor can be prevented from decreasing. 2. A pyrolysis control device as described in 1 above, wherein the height variable is a variable indicating the amount of decrease in outlet pressure relative to the inlet pressure of the reactor, and the replenishment process includes a process of changing the replenishment amount in accordance with the amount of decrease when the replenishment amount of the catalyst is zero or more, and when the amount of decrease is large, the replenishment amount is equal to or less than the replenishment amount when the amount of decrease is small.

[0075] According to the above-mentioned configuration, by using the amount of decrease, the amount of catalyst can be controlled more easily than by grasping the actual height of the catalyst in the reactor by measurement or the like. 3. A thermal cracking control system comprising the thermal cracking control device described in 1 or 2 above, the reactor, the replenishment device, and a heating device, wherein the heating device is a device for heating the hydrocarbons prior to being supplied to the reactor.

[0076] In the above configuration, the temperature of the hydrocarbons in the reactor can be easily controlled to a temperature appropriate for thermal cracking. 4. A thermal decomposition control system as described in claim 3, wherein the value obtained by dividing the height of the solid particles containing the catalyst in the reactor in a stationary state by their characteristic diameter is 2 or less, the characteristic diameter is twice the square root of the value obtained by dividing the area of ​​a cross section of the reactor perpendicular to the flow direction of the hydrocarbons by pi, and the outlet temperature of the reactor is lower than the inlet temperature of the reactor.

[0077] In the above configuration, it is possible to suppress the pressure fluctuation in the reactor from increasing due to poor flow. 5. The pyrolysis control system according to claim 4, which is configured to execute a feedback process that operates the heating device based on a feedback control manipulated variable in which the outlet temperature is a controlled variable.

[0078] In the above-described configuration, the outlet temperature of the reactor can be reliably reduced by executing feedback control. 6. A pyrolysis control system as described in 3 or 4 above, comprising a plurality of the reactors, the replenishing devices, and the heating devices, the plurality of reactors being connected in series, the plurality of reactors including an upstream reactor and a downstream reactor which are adjacent reactors, the plurality of heating devices including an upstream heating device and a downstream heating device, the hydrocarbons heated by the upstream heating device being supplied to the upstream reactor, the hydrocarbons flowing out of the upstream reactor being heated by the downstream heating device, and the hydrocarbons heated by the downstream heating device being supplied to the downstream reactor.

[0079] According to the above configuration, the conversion rate of hydrocarbons in the entire reactor can be increased compared to the conversion rate of hydrocarbons in a single reactor. 7. A pyrolysis control system described in any one of 3 or 6 above, further comprising an internal heating device for heating the inside of the reactor, and configured to execute an outlet temperature acquisition process and a temperature control process, wherein the outlet temperature acquisition process is a process for acquiring a value of an outlet temperature variable, the outlet temperature variable being a variable indicating the temperature at the outlet of the reactor, and the temperature control process is a process for using the value of the outlet temperature variable as input and operating the internal heating device so as to bring the temperature of the reactor outlet closer to the temperature of the reactor inlet.

[0080] According to the above-mentioned configuration, the amount of heat lost due to pyrolysis can be compensated for by the internal heating device. [Explanation of symbols]

[0081] 10...Compressor 12...Heating device 20…Reactor 22…Entrance 24...Entrance 26...Exit 30…Replenishment device 32...Catalyst 40... Pyrolysis control device 44…Storage device 60...Heating device

Claims

1. The reactor that thermally decomposes hydrocarbons into hydrogen and carbon is the object of control. A catalyst replenishing device is connected to the reactor, configured to perform a height variable acquisition process and a refill process; The height variable acquisition process is a process for acquiring a value of a height variable, The height variable is a variable indicating the height of the catalyst in the catalyst, A pyrolysis control device, wherein the replenishment process is a process of replenishing the catalyst to the reactor by operating the replenishment device in response to the value of the height variable.

2. The height variable is a variable indicating an amount of decrease in outlet pressure relative to an inlet pressure of the reactor, The pyrolysis control device of claim 1, wherein the replenishment process includes a process of changing the replenishment amount in accordance with the amount of decrease under the condition that when the replenishment amount of the catalyst is zero or more, the replenishment amount when the amount of decrease is large is equal to or less than the replenishment amount when the amount of decrease is small.

3. The pyrolysis control device according to claim 1, the reactor, the replenishing device, and a heating device, The heating device is a device that heats the hydrocarbons prior to being fed to the reactor.

4. a value obtained by dividing a height of the solid particles containing the catalyst in a stationary state in the reactor by a representative diameter is 2 or less; the representative diameter is twice the square root of the area of ​​a cross section of the reactor perpendicular to the flow direction of the hydrocarbons divided by pi; 4. The pyrolysis control system of claim 3, wherein the reactor outlet temperature is less than the reactor inlet temperature.

5. The pyrolysis control system according to claim 4 , which is configured to execute a feedback process that is a process of operating the heating device based on a manipulated variable of feedback control in which the outlet temperature is a controlled variable.

6. The reactor, the replenishing device, and the heating device are provided in a plurality of units, The reactors are connected in series, The plurality of reactors include an upstream reactor and a downstream reactor which are adjacent to each other, The plurality of heating devices include an upstream heating device and a downstream heating device, The hydrocarbons heated by the upstream heating device are supplied to an upstream reactor; The hydrocarbons flowing out from the upstream reactor are heated by a downstream heating device; 5. The pyrolysis control system of claim 4, wherein the hydrocarbons heated by the downstream heating device are supplied to a downstream reactor.

7. The reactor further includes an internal heating device for heating the inside of the reactor, The outlet temperature acquisition process and the temperature control process are configured to execute the outlet temperature acquisition process and the temperature control process. The outlet temperature acquisition process is a process for acquiring a value of an outlet temperature variable, The outlet temperature variable is a variable indicating a temperature at an outlet of the reactor, The pyrolysis control system according to claim 3 , wherein the temperature control process is a process of operating the internal heating device so as to bring the temperature of the reactor outlet closer to the temperature of the reactor inlet using the value of the outlet temperature variable as an input.

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