JP2022163279A - Carbon dioxide recovery control device, carbon dioxide recovery device, hydrocarbon production device, carbon dioxide recovery method, and program - Google Patents

Abstract

To provide a carbon dioxide recovery control device suppressing a variation in carbon dioxide concentration in a recovery gas containing carbon dioxide recovered from a mixed gas containing carbon dioxide using an adsorption tower.SOLUTION: A carbon dioxide recovery control device includes: a step control part for repeatedly performing a first step of performing an adsorption step of supplying a mixed gas to a first adsorption tower and at the same time performing a desorption step of supplying hydrogen to a second adsorption tower, and a second step of performing an adsorption step of supplying the mixed gas to a second adsorption tower and at the same time performing a desorption step of supplying hydrogen to the first adsorption tower; a breakthrough time prediction part for predicting breakthrough time at a predetermined prediction time in the adsorption tower where the adsorption step is performed; and a hydrogen flow rate determination part for determining a hydrogen flow rate flowing in the desorption step according to a predicted breakthrough time. The step control part switches between the first step and the second step based on carbon dioxide breakthrough information.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a technique for recovering carbon dioxide from a mixed gas containing carbon dioxide using an adsorption tower.

Conventionally, there has been proposed a technique for removing impurities contained in gas or liquid using an adsorption device filled with an adsorbent (see, for example, Patent Document 1). Patent Literature 1 describes an adsorption apparatus that alternately performs an impurity adsorption step and a desorption (regeneration) step using two columns packed with an adsorbent. In this adsorption apparatus, when the flow rate of the inflowing gas in the adsorption process is lower than the design value, the time of the adsorption process is extended until the total flow rate of the inflow gas reaches the design value, and the regeneration process is operated as designed. It is described that, as a result, even when the flow rate of the inflowing gas is reduced, the performance of the adsorption tower can be utilized to the maximum, and the energy efficiency of impurity separation is increased.

JP-A-62-176516

However, according to the technique described in Patent Document 1, when the flow rate of the inflowing gas is reduced, the adsorption step is extended and the desorption step is left as it is. there will be time to Using the technology described in Patent Document 1, for example, when separating and recovering carbon dioxide from a mixed gas containing carbon dioxide, carbon dioxide comes out of the adsorption tower in the desorption step, so while waiting does not emit carbon dioxide. That is, the concentration of carbon dioxide coming out of the adsorption tower fluctuates.

A hydrocarbon synthesizer that hydrocarbonates the carbon dioxide recovered by the adsorption tower may be connected downstream of the adsorption tower. In such a configuration, if the concentration of carbon dioxide fluctuates, the hydrocarbon catalyst may be deactivated if the amount of carbon dioxide supplied to the hydrocarbon synthesis device is excessive. If too much hydrogen is supplied, the purity of hydrocarbons obtained from the hydrocarbon synthesizing apparatus may be lowered.

Therefore, in a carbon dioxide separation and recovery apparatus that separates and recovers carbon dioxide from a mixed gas containing carbon dioxide using an adsorption tower, a technique for suppressing fluctuations in the concentration of carbon dioxide to be recovered is desired.

The present invention has been made to solve the above-described problems, and suppresses fluctuations in carbon dioxide concentration in a recovered gas containing carbon dioxide recovered from a mixed gas containing carbon dioxide using an adsorption tower. The purpose is to provide technology to

The present invention has been made to solve at least part of the above problems, and can be implemented as the following modes.

(1) According to one aspect of the present invention, carbon dioxide recovery control for recovering carbon dioxide from a mixed gas containing carbon dioxide using a plurality of adsorption towers including at least a first adsorption tower and a second adsorption tower. A carbon dioxide capture controller is provided that: This carbon dioxide recovery control device comprises a first step of executing an adsorption step of supplying the mixed gas to the first adsorption tower and simultaneously executing a desorption step of supplying hydrogen to the second adsorption tower; a process control unit for repeatedly performing a second step of performing an adsorption step of supplying the mixed gas to the second adsorption tower and simultaneously performing a desorption step of supplying hydrogen to the first adsorption tower; a breakthrough time prediction unit for predicting a breakthrough time, which is a time from a predetermined prediction time until carbon dioxide leaks out of the adsorption tower, in the adsorption tower in which the adsorption step is being performed; and the breakthrough time. a hydrogen flow rate determination unit that determines a hydrogen flow rate for controlling the flow rate of hydrogen to be circulated to the adsorption tower in the desorption process being simultaneously performed according to the breakthrough time predicted by the prediction unit; , wherein the process control unit controls the flow rate of hydrogen to be circulated in the adsorption tower in which the desorption step is performed so as to be the hydrogen flow rate determined by the hydrogen flow rate determination unit. Then, carbon dioxide breakthrough information, which is information on carbon dioxide breakthrough in the adsorption tower in which the adsorption step is being performed, is acquired, and based on the carbon dioxide breakthrough information, carbon dioxide breakthrough has occurred. When or just before breakthrough of carbon dioxide occurs, the first step and the second step are switched.

According to this configuration, the first step and the second step are carried out until carbon dioxide breaks through or just before it breaks through, respectively, in the adsorption step. Therefore, the periods of the first step and the second step change according to the flow rate of the mixed gas supplied to the adsorption tower and the carbon dioxide concentration in the mixed gas. In the adsorption step, the mixed gas is supplied until the carbon dioxide breaks through or just before the carbon dioxide breaks through, so the adsorption amount of carbon dioxide is substantially full (maximum adsorption amount). On the other hand, if the flow rate of hydrogen is constant in the desorption process, the total amount of hydrogen supplied to the adsorption tower fluctuates during the entire period of the desorption process, resulting in an excess or deficiency of hydrogen. However, according to this configuration, since the flow rate of hydrogen supplied in the desorption step (having the same period) performed simultaneously with the adsorption step is determined according to the breakthrough time, the length of the desorption step , the amount of hydrogen supplied to the adsorption tower during the entire desorption step can be appropriately controlled. As a result, fluctuations in carbon dioxide concentration in the recovered gas containing carbon dioxide recovered from the mixed gas containing carbon dioxide using the adsorption tower can be suppressed.

(2) In the carbon dioxide recovery control device of the above aspect, the breakthrough time prediction unit predicts the breakthrough time every predetermined time, and the hydrogen flow rate determination unit predicts the predicted breakthrough According to time, the hydrogen flow rate is updated every predetermined time, the predetermined time is dt, the predicted time is n (n is an integer of 1 or more), and the failure predicted at the predicted time n Assuming that the elapsed time is t(n), the hydrogen flow rate determining unit determines the predicted breakthrough time t(n) at the predicted time n and the predicted breakthrough time t at the predicted time (n−1). If the relationship with (n-1) is the first relationship, the hydrogen flow rate at the predicted time n is reduced from the hydrogen flow rate at the predicted time (n-1), and if the relationship is the second relationship increases the hydrogen flow rate at predicted time n from the hydrogen flow rate at predicted time (n-1), and in the case of the third relationship, increases the hydrogen flow rate at predicted time n by predicted time (n -1), the first relationship is t (n-1) < t (n) + dt, and the second relationship is t (n-1) > t (n) +dt, and the third relation may be t(n−1)=t(n)+dt.

According to this configuration, the breakthrough time is predicted moment by moment in one adsorption step, and the flow rate of hydrogen is updated moment by moment according to the breakthrough time. Therefore, it is possible to change the flow rate of hydrogen with higher accuracy. Further, when the relationship between the breakthrough time predicted at the current prediction time and the prediction time one hour before is the first relation, the length of the adsorption process predicted at the prediction time one hour before is predicted at the current time. Since the length of the adsorption step is long, the total amount of hydrogen supplied in the desorption step can be made appropriate by reducing the flow rate of hydrogen. When the relationship between the breakthrough times predicted at the current prediction time and the prediction time one hour earlier is the second relation, the length of the adsorption process predicted at the prediction time one hour earlier is compared with the length of the adsorption process predicted at the current time. Since the length of the process is short, the total amount of hydrogen supplied in the desorption process can be made appropriate by increasing the flow rate of hydrogen. When the relationship between the breakthrough times predicted at the current prediction time and the prediction time one hour earlier is the third relation, the length of the adsorption process predicted at the prediction time one hour earlier and the adsorption predicted at the current time Since the length of the process is equal (unchangeable), the total amount of hydrogen supplied in the desorption process can be made appropriate by maintaining the flow rate of hydrogen. That is, by updating the flow rate of hydrogen in this manner, the supply rate of hydrogen can be made more accurate and appropriate, and fluctuations in the concentration of carbon dioxide in the recovered gas can be further suppressed.

(3) In the carbon dioxide recovery control device of the above aspect, the hydrogen flow amount determination unit determines the amount of hydrogen that has flowed through the adsorption tower from the start of the desorption step to the prediction time, and the desorption The total amount of hydrogen that can be circulated in the adsorption tower during the entire period of the process is obtained, and the hydrogen circulation amount that is circulated in the adsorption tower during the desorption process after the prediction time is calculated by the following formula (1). may decide.
mf(n)=(ma−mp)/t(n) (1)
However, mf(n): the amount of hydrogen flowing through the adsorption tower during the desorption process after the predicted time n, mp: the amount of hydrogen flowing through the adsorption tower from the start of the desorption process to the predicted time n, ma : Total amount of hydrogen that can flow through the adsorption tower during the entire period of the desorption process, t(n): Predicted breakthrough time at predicted time n

According to this configuration, the amount of hydrogen actually supplied to the adsorption tower during the desorption process is used to determine the hydrogen flow rate in the remaining desorption process, so the calculation accuracy of the appropriate hydrogen flow rate is improved. be able to.

(4) In the carbon dioxide recovery control device of the above aspect, the breakthrough time prediction unit predicts, in the adsorption step, the total amount of the mixed gas that has flowed into the adsorption tower by the prediction time, and Acquire the amount of mixed gas that can be processed and the rated mixed gas flow rate that is the flow rate of the mixed gas predetermined for each supply source of the mixed gas, and predict the breakthrough time by the following formula (2) You may
t(n)=(qc−q(n))/qf (2)
However, t(n): breakthrough time predicted at predicted time n qc: mixed gas amount that can be processed in the adsorption step q(n): total amount of mixed gas that has flowed up to predicted time n qf: rated mixed gas flow rate With this configuration, the breakthrough time can be easily predicted.

(5) In the carbon dioxide recovery control device of the above aspect, the breakthrough time predicting unit includes the flow rate of the mixed gas flowing into the adsorption tower, the temperature of the mixed gas, and carbon dioxide in the mixed gas. obtaining the concentration of and, in the adsorption step, calculating the total amount of carbon dioxide that has flowed in by the prediction time using the flow rate of the mixed gas and the concentration of carbon dioxide in the mixed gas, The saturated adsorption amount of carbon dioxide in the adsorption step is calculated using the temperature of the mixed gas at the predicted time and the concentration of carbon dioxide in the mixed gas, and is predetermined for each supply source of the mixed gas. A rated carbon dioxide flow rate, which is the flow rate of the carbon dioxide obtained, may be obtained, and the breakthrough time may be predicted by the following formula (3).
t(n)=(Ca−C(n))/Cf (3)
However, t(n): Breakthrough time predicted at predicted time n Ca: Saturated adsorption amount of carbon dioxide C(n): Total amount of carbon dioxide that has flowed up to predicted time n Cf: Rated carbon dioxide flow rate

According to this configuration, the breakthrough time can be predicted using the saturated adsorption amount of carbon dioxide, which varies according to the temperature of the mixed gas and the carbon dioxide concentration in the mixed gas. can be improved.

(6) According to another aspect of the present invention, a carbon dioxide capture device is provided. This carbon dioxide recovery device includes the carbon dioxide recovery control device of the above-described form, and an adsorption tower capable of separating carbon dioxide from a mixed gas containing carbon dioxide, and includes at least a first adsorption tower and a second adsorption tower. A plurality of adsorption towers, a mixed gas supply section capable of supplying the mixed gas to the plurality of adsorption towers, and a hydrogen supply section capable of supplying hydrogen to the plurality of adsorption towers.
According to this configuration, it is possible to suppress variation in carbon dioxide concentration in the recovered gas containing carbon dioxide recovered from the mixed gas containing carbon dioxide using the adsorption tower.

(7) According to another aspect of the present invention, a hydrocarbon production apparatus is provided. This hydrocarbon production device has a carbon dioxide recovery device of the above-described form and a hydrocarbonation catalyst inside, and uses a recovered gas containing carbon dioxide and hydrogen flowing out of the carbon dioxide recovery device to produce a hydrocarbon compound and a hydrocarbon production section that produces
According to this configuration, it is possible to suppress the fluctuation of the concentration of carbon dioxide in the recovery gas containing carbon dioxide recovered using the adsorption tower from the mixed gas containing carbon dioxide, so that the carbonization of the hydrocarbon generation unit Deactivation of the hydrogenation catalyst can be suppressed. Also, the methane purity of the gas produced by the hydrocarbon production section can be improved.

It should be noted that the present invention can be implemented in various aspects, including, for example, a carbon dioxide recovery method, a program for controlling a carbon dioxide recovery device, a carbon dioxide recovery system, a hydrocarbon production system, a methane production system, It can be implemented in the form of methods for controlling these devices and systems, programs for controlling these devices and systems, server devices for distributing these programs, non-temporary storage media storing programs, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows schematic structure of the hydrocarbon production apparatus of 1st Embodiment. FIG. 4 is an explanatory diagram of switching timing of adsorption towers in the carbon dioxide recovery device. FIG. 4 is an explanatory diagram of the first step of carbon dioxide recovery control; FIG. 4 is an explanatory diagram of a second step of carbon dioxide recovery control; 4 is a flowchart of carbon dioxide recovery control; 4 is a flowchart showing a flow of breakthrough time prediction processing; It is an explanatory view for explaining breakthrough time prediction processing. 4 is a flow chart showing the flow of hydrogen distribution amount determination processing. FIG. 4 is an explanatory diagram showing an example of the relationship between breakthrough time (n) and hydrogen flow rate (n); It is an explanatory view showing a schematic structure of a hydrocarbon production device of a second embodiment. 9 is a flow chart showing the flow of breakthrough time prediction processing in the second embodiment.

<First Embodiment>
FIG. 1 is an explanatory diagram showing a schematic configuration of a hydrocarbon production apparatus 100 of the first embodiment. The hydrocarbon production device 100 is a device for producing hydrocarbon compounds using a mixed gas of carbon dioxide (CO ₂ ) and hydrogen (H ₂ ), and includes a carbon dioxide recovery device 200, a hydrocarbon production unit 60, Prepare. Specifically, in the carbon dioxide recovery device 200, the hydrocarbon production device 100 recovers carbon dioxide from a mixed gas containing carbon dioxide, and uses the recovered carbon dioxide to produce hydrocarbons. In this embodiment, an example of producing methane (CH ₄ ) as a hydrocarbon is shown, but hydrocarbon compounds other than methane (CH ₄ ), for example, compounds composed of carbon and hydrogen such as ethane and propane, and methanol may produce compounds composed primarily of carbon and hydrogen, such as

The hydrocarbon generation unit 60 has a hydrocarbonation catalyst inside, and is composed of a recovery gas (including carbon dioxide and hydrogen) supplied from the carbon dioxide recovery device 200, hydrogen supplied from an external hydrogen supply source, is used to generate methane, and a gas containing methane as a main component (hereinafter also referred to as "product gas") can be supplied to the outside. The hydrocarbon generator 60 is connected to the carbon dioxide recovery device 200 via the recovered gas flow path 72 and is connected to an external hydrogen supply source via the hydrogen flow path 62 . The hydrogen channel 62 is provided with a flow rate controller 62 a that adjusts the flow rate of hydrogen flowing through the hydrogen channel 62 . A hydrogen flow rate in the flow controller 62a is set in advance. Further, the hydrocarbon generation section 60 is connected to the product gas flow path 63 . For example, by connecting a storage tank to the other end of the product gas flow path 63, the product gas can be stored in the storage tank. In this embodiment, as will be described later, in the carbon dioxide recovery device 200, fluctuations in the flow rate and concentration of the recovered gas can be suppressed, so the hydrocarbon generation unit 60 supplies the product gas with high methane purity to the outside. be able to.

The carbon dioxide recovery device 200 recovers carbon dioxide from a mixed gas containing carbon dioxide using an adsorption tower. In this embodiment, exhaust gas discharged from a combustion furnace, an internal combustion engine, or the like is exemplified as a mixed gas containing carbon dioxide. The carbon dioxide recovery device 200 includes a plurality of adsorption towers (first adsorption tower 11 and second adsorption tower 12), an exhaust gas flow channel 20, an offgas flow channel 25, a hydrogen flow channel 30, and a recovered gas flow channel 40. , a recovery gas tank 70 and a carbon dioxide recovery control device 50 . In the following description, when the first adsorption tower 11 and the second adsorption tower 12 are not distinguished, they are simply called the adsorption tower 10 . In the carbon dioxide recovery device 200, carbon dioxide adsorbed in the adsorption tower 10 is desorbed using hydrogen as a purge gas.

The 1st adsorption tower 11 and the 2nd adsorption tower 12 are formed in cylinder shape, respectively, and adsorbents 11a and 12a are stored in each inside. The adsorbents 11a and 12a are materials having carbon dioxide storage performance, such as zeolite, activated carbon, and silica gel. An exhaust gas channel 20 , a hydrogen channel 30 , and a recovered gas channel 40 are connected to each of the first adsorption tower 11 and the second adsorption tower 12 .

The exhaust gas passage 20 is connected to an external exhaust gas supply device for discharging exhaust gas containing carbon dioxide, such as a combustion furnace or an internal combustion engine, and the exhaust gas discharged by the exhaust gas supply device flows. The exhaust gas flowing through the exhaust gas channel 20 is supplied to the first adsorption tower 11 and the second adsorption tower 12 via the exhaust gas branch channels 21 and 22 . Exhaust gas inlet valves 21a and 22a are provided in the exhaust gas branch passages 21 and 22, respectively. Each of the flue gas inlet valves 21a and 22a controls the supply of flue gas into the first adsorption tower 11 and the second adsorption tower 12 according to commands from the carbon dioxide recovery control device 50, which will be described later. In this embodiment, exhaust gas is exemplified as the mixed gas containing carbon dioxide, but the mixed gas containing carbon dioxide may not be exhaust gas. The exhaust gas passage 20, the exhaust gas branch passages 21 and 22, and the exhaust gas inlet valves 21a and 22a in this embodiment are collectively referred to as a "mixed gas supply section".

The offgas channel 25 is connected to the first adsorption tower 11 via the offgas branch channel 23 and is connected to the second adsorption tower 12 via the offgas branch channel 24 . Carbon dioxide contained in the exhaust gas is trapped by the adsorbent, and offgas containing nitrogen and the like that is not trapped by the adsorbent flows through the offgas channel 25 . The off-gas is released outside the carbon dioxide capture device 200, for example, to the atmosphere. The offgas channel 25 is connected to the offgas branch channels 23 and 24 via a three-way valve 25a, and the first adsorption tower 11 and the second adsorption tower 12 are discharged in accordance with a command from the carbon dioxide recovery control device 50, which will be described later. Control off-gas emissions.

Temperature sensors 84 and 85 are provided in the offgas branch channel 23 and the offgas branch channel 24, respectively. The temperature sensors 84 and 85 detect the temperature of the offgas discharged from the first adsorption tower 11 and the second adsorption tower 12, respectively, and output the detection results to the carbon dioxide recovery control device 50.

The hydrogen channel 30 is connected to an external hydrogen supply source that supplies hydrogen as a purge gas to the insides of the first adsorption tower 11 and the second adsorption tower 12 . The hydrogen flow path 30 is provided with a flow rate controller 30 a that adjusts the flow rate of hydrogen flowing through the hydrogen flow path 30 according to a command from the carbon dioxide recovery control device 50 . Hydrogen flowing through the hydrogen channel 30 is supplied to the first adsorption tower 11 and the second adsorption tower 12 via hydrogen branch channels 31 and 32 . Hydrogen inlet valves 31a and 32a are provided in the hydrogen branch passages 31 and 32, respectively. Each of the hydrogen inlet valves 31 a and 32 a controls the flow of hydrogen into the first adsorption tower 11 and the second adsorption tower 12 according to commands from the carbon dioxide recovery control device 50 . The hydrogen flow path 30, the flow controller 30a, the hydrogen branch flow paths 31 and 32, and the hydrogen inlet valves 31a and 32a in this embodiment are collectively referred to as a "hydrogen supply unit".

The recovered gas channel 40 is connected to the first adsorption tower 11 and the second adsorption tower 12 via recovered gas branch channels 41 and 42, respectively. A recovered gas, which is a mixed gas of carbon dioxide desorbed from the adsorbents 11a and 12a and hydrogen supplied to the first adsorption tower 11 and the second adsorption tower 12 as a purge gas, flows through the recovered gas flow path 40. . The collected gas branch passages 41 and 42 are provided with collected gas outlet valves 41a and 42a. The collected gas outlet valves 41a and 42a respectively control the flows of the collected gas from the first adsorption tower 11 and the second adsorption tower 12 according to commands from the carbon dioxide recovery control device 50 .

The collected gas tank 70 is connected to the collected gas flow path 40 and temporarily stores the collected gas flowing through the collected gas flow path 40 . The collected gas tank 70 is also connected to the hydrocarbon generating section 60 via a collected gas flow path 72 and supplies the collected gas to the hydrocarbon generating section 60 .

The flow meter 81 is provided in the exhaust gas flow path 20 at a position on the upstream side of the position where the exhaust gas branch flow path 21 is connected. The flow meter 81 detects the flow rate of exhaust gas flowing through the exhaust gas flow path 20 . The flow meter 81 outputs the detected flue gas flow rate to the carbon dioxide recovery control device 50 .

The carbon dioxide recovery control device 50 is a computer (information processing device) including a ROM, a RAM, and a CPU. , and controls the entire carbon dioxide capture device 200, such as valve opening/closing control. In addition, the carbon dioxide recovery control device 50 determines the flow rate of hydrogen to be supplied to the adsorption tower 10 (described later).

The carbon dioxide recovery control device 50 includes a process control section 51 , a breakthrough time prediction section 52 , a hydrogen flow rate determination section 53 and a storage section 54 .

The carbon dioxide recovery control device 50 causes the first adsorption tower 11 to perform an adsorption step of supplying exhaust gas, and at the same time, a first step of performing a desorption step of supplying hydrogen to the second adsorption tower 12, and a second adsorption. Carbon dioxide recovery control is executed to repeatedly perform the adsorption step of supplying exhaust gas to the tower 12 and the second step of performing the desorption step of supplying hydrogen to the first adsorption tower 11 at the same time. In each adsorption tower 10, an adsorption step and a desorption step are alternately repeated, thereby recovering carbon dioxide from the exhaust gas. The carbon dioxide recovery control device 50 switches the process in conjunction with breakthrough of carbon dioxide in the adsorption tower 10 in which the adsorption process is being performed (described later in detail). In the present embodiment, the adsorption step is a step of supplying exhaust gas to the adsorption tower 10 and the desorption step is a step of supplying hydrogen to the adsorption tower 10 .

The process control unit 51 cooperates with the breakthrough time prediction unit 52 and the hydrogen flow rate determination unit 53 to execute carbon dioxide recovery control, which will be described later. The process control unit 51 controls the exhaust gas inlet valves 21a and 22a, the three-way valve 25a, the flow rate controller 30a, the hydrogen inlet valves 31a and 32a, and the collected gas outlet valves 41a and 42a described above, so that the adsorption in the adsorption tower 10 The step and the desorption step are repeatedly performed.

The breakthrough time prediction unit 52 predicts the breakthrough time, which is the time from a predetermined prediction time until carbon dioxide leaks out of the adsorption tower 10 in the adsorption tower 10 in which the adsorption step is being performed. In this embodiment, the breakthrough time prediction unit 52 acquires the exhaust gas flow rate measured by the flow meter 81 provided in the exhaust gas flow path 20, and based on the total flow rate of the exhaust gas that can be separated by the adsorption tower, the remaining adsorption Calculate the possible period (time until breakthrough) (described in detail later). In the present embodiment, the breakthrough time prediction unit 52 predicts the breakthrough time multiple times while the adsorption step is being performed. That is, the prediction time, which is the time at which the breakthrough time is predicted, is set at predetermined intervals.

According to the breakthrough time predicted by the breakthrough time prediction unit 52, the hydrogen distribution amount determination unit 53 distributes hydrogen to the adsorption tower 10 in the desorption step being performed simultaneously with the adsorption step for which the breakthrough time is predicted. A hydrogen distribution rate is determined for controlling the hydrogen distribution rate (described in detail later).

The storage unit 54 stores a rated exhaust gas flow rate 55 and a treatable exhaust gas amount 56 . The rated exhaust gas flow rate 55 is a predetermined exhaust gas flow rate for each exhaust gas supply source, and a value unique to the exhaust gas supply device connected to the hydrocarbon production device 100 is input in advance by the user or the like. The processable exhaust gas amount 56 is the total amount of exhaust gas that can be processed by the adsorption tower 10. For example, depending on the capacity of the adsorption tower 10, the type of adsorbent, the packing rate of the adsorbent, etc., It is defined. Like the rated exhaust gas flow rate 55, the treatable exhaust gas amount 56 may be input by the user, or may be stored in advance when the hydrocarbon production apparatus 100 is manufactured.

FIG. 2 is an explanatory diagram of the switching timing of the adsorption tower 10 in the carbon dioxide recovery device 200 of this embodiment. In the carbon dioxide recovery control of this embodiment, as shown in the figure, the first step and the second step constitute one cycle, and this cycle is repeated multiple times. In each step, each of the adsorption step and the desorption step (hydrogen supply) is performed in either of the two adsorption towers (first adsorption tower 11 and second adsorption tower 12). Specifically, in the first step, an adsorption step is performed in the first adsorption tower 11 and a desorption step is performed in the second adsorption tower 12 . In the second step, a desorption step is performed in the first adsorption tower 11 and an adsorption step is performed in the second adsorption tower 12 . In the carbon dioxide recovery device 200 of the present embodiment, in this way, one adsorption tower 10 adsorbs carbon dioxide in the exhaust gas, and the other adsorption tower 10 desorbs the adsorbed carbon dioxide. Thereby, it is possible to steadily supply the carbon dioxide-containing gas (exhaust gas).

Focusing on one adsorption tower 10, an adsorption step and a desorption step are repeatedly performed. In FIG. 2, the serial numbers N of the steps that are repeated are listed in order from 0. In FIG. The first adsorption tower 11 will be described below as an example. In the adsorption step, exhaust gas is supplied to the first adsorption tower 11 (first step). Immediately before carbon dioxide breaks through in the first adsorption tower 11, the process shifts to the desorption step (second step). In the desorption step, hydrogen as a purge gas is supplied to the first adsorption tower 11 . When hydrogen as a purge gas is supplied to the first adsorption tower 11, the partial pressure of carbon dioxide inside the first adsorption tower 11 decreases, so that the carbon dioxide adsorbed on the adsorbent 11a is desorbed from the adsorbent 11a. release. Immediately before carbon dioxide breaks through the second adsorption tower 12 in the second step, the first adsorption tower 11 shifts to the adsorption step (first step).

Thus, in the carbon dioxide recovery device 200 of the present embodiment, switching between the first step and the second step is performed immediately before carbon dioxide breaks through in the adsorption tower 10 in which the adsorption step is being performed. Therefore, as shown, the lengths of the plurality of first steps and the plurality of second steps may differ from each other. However, the lengths of the adsorption step and the desorption step in the first step are the same, and the lengths of the adsorption step and the desorption step in the second step are the same. Switching between the first step and the second step will be described in detail later.

FIG. 3 is an explanatory diagram of the first step of carbon dioxide recovery control in the carbon dioxide recovery device 200. As shown in FIG. FIG. 4 is an explanatory diagram of the second step of carbon dioxide recovery control in the carbon dioxide recovery device 200. As shown in FIG. As described above, the carbon dioxide recovery device 200 recovers carbon dioxide from the exhaust gas by sequentially supplying the exhaust gas to each of the two adsorption towers 10 (the first adsorption tower 11 and the second adsorption tower 12). Each of the first adsorption tower 11 and the second adsorption tower 12 functions as an adsorption tower in which carbon dioxide is adsorbed by the adsorbent and a desorption tower in which carbon dioxide adsorbed by the adsorbent is desorbed.

The first adsorption tower 11 functions as an adsorption tower in the first step shown in FIG. 3, and functions as a desorption tower in the second step shown in FIG. In FIGS. 3 and 4, the flows of exhaust gas, hydrogen, and recovered gas are indicated by thick solid lines. As shown in FIG. 3, exhaust gas is supplied to the first adsorption tower 11 functioning as an adsorption tower. Hydrogen is supplied to the second adsorption tower 12 that functions as a desorption tower, and carbon dioxide desorbed from the adsorbent is discharged together with hydrogen as a recovered gas.

In the first step shown in FIG. 3, exhaust gas is supplied to the first adsorption tower 11 using the exhaust gas flow path 20 (adsorption step). Specifically, the carbon dioxide capture control device 50 opens the exhaust gas inlet valve 21a and controls each valve such that the offgas branch channel 23 and the offgas channel 25 are connected via the three-way valve 25a. . Thereby, the exhaust gas flowing through the exhaust gas channel 20 is supplied to the first adsorption tower 11 via the exhaust gas branch channel 21 . In the first adsorption tower 11, the carbon dioxide contained in the exhaust gas is trapped in the adsorbent 11a, and the nitrogen, water, and the like that are not trapped in the adsorbent 11a pass through the offgas branch channel 23 and the offgas channel 25 as offgas into dioxide. It is discharged to the outside of the carbon capture device 200, eg, to the atmosphere.

In the first step, a desorption step is performed in the second adsorption tower 12 at the same time as the adsorption step. In the desorption step, hydrogen is supplied to the second adsorption tower 12 using the hydrogen channel 30 . Specifically, the carbon dioxide recovery control device 50 opens the hydrogen inlet valve 32a and closes the hydrogen inlet valve 31a. Then, the collected gas outlet valve 42a is opened and the collected gas outlet valve 41a is closed. The flow rate controller 30 a controls the flow rate of hydrogen according to the command from the carbon dioxide recovery control device 50 so that the flow rate of hydrogen is determined by the hydrogen flow rate determination unit 53 . As will be described in detail later, in the carbon dioxide recovery control device 50, the hydrogen flow rate determined by the hydrogen flow rate determination unit 53 changes from moment to moment, so the flow rate of hydrogen supplied to the second adsorption tower 12 also changes from moment to moment. and change. When hydrogen is supplied to the second adsorption tower 12, the partial pressure of carbon dioxide inside the second adsorption tower 12 decreases, so that the carbon dioxide adsorbed on the adsorbent 12a is desorbed from the adsorbent 12a. The desorbed carbon dioxide flows into the recovered gas branch channel 42 together with hydrogen, flows through the recovered gas channel 40 , and flows into the recovered gas tank 70 . In the desorption step, hydrogen is supplied to the second adsorption tower 12, whereby the adsorbent 12a is cooled to be in a state capable of adsorbing carbon dioxide.

As shown in FIG. 4 , in the second step, the adsorption step is performed in the second adsorption tower 12 and the desorption step is performed in the first adsorption tower 11, contrary to the first step. Specifically, the carbon dioxide recovery control device 50 opens the exhaust gas inlet valve 22a and controls each valve so that the offgas branch channel 24 and the offgas discharge channel 25 are connected via the three-way valve 25a. do. Thereby, the exhaust gas flowing through the exhaust gas channel 20 is supplied to the second adsorption tower 12 via the exhaust gas branch channel 22 . In the second adsorption tower 12, the carbon dioxide contained in the exhaust gas is trapped in the adsorbent 12a, and the nitrogen, moisture, etc. that are not trapped in the adsorbent 12a pass through the offgas branch channel 24 and the offgas channel 25 as offgas to form dioxide. It is discharged outside the carbon recovery device 200 .

In the second step, a desorption step is performed in the first adsorption tower 11 at the same time as the adsorption step. In the desorption step, hydrogen is supplied to the first adsorption tower 11 using the hydrogen channel 30 . Specifically, the carbon dioxide recovery control device 50 opens the hydrogen inlet valve 31a and closes the hydrogen inlet valve 32a. Then, the collected gas outlet valve 41a is opened and the collected gas outlet valve 42a is closed. The flow rate controller 30 a controls the flow rate of hydrogen according to the command from the carbon dioxide recovery control device 50 so that the flow rate of hydrogen is determined by the hydrogen flow rate determination unit 53 . When hydrogen is supplied to the first adsorption tower 11, carbon dioxide adsorbed on the adsorbent 11a is desorbed from the adsorbent 11a, flows into the recovered gas branch channel 41 together with hydrogen, and flows through the recovered gas channel 40. , flows into the recovery gas tank 70 .

FIG. 5 is a flow chart of carbon dioxide recovery control in the carbon dioxide recovery device 200 . The carbon dioxide recovery control is started when the hydrocarbon production apparatus 100 is activated and an instruction to start carbon dioxide recovery is input, and is repeatedly executed until an end instruction is input. Carbon dioxide recovery control is executed by the process control unit 51, the breakthrough time prediction unit 52, and the hydrogen flow rate determination unit 53 in cooperation.

The process control unit 51 sets the process serial number N (FIG. 2) to N=0 in step S10, and sets the predicted time n in each adsorption process to n=0 in step S11.

In step S20, the process control unit 51 causes one adsorption tower 10 to perform an adsorption process. Here, the exhaust gas discharged from the exhaust gas supply device is directly supplied to the adsorption tower 10 without adjusting the flow rate. That is, when the flow rate of the exhaust gas discharged from the exhaust gas supply device fluctuates, the flow rate of the exhaust gas flowing into the adsorption tower 10 also fluctuates. When N = 2m (m is an integer of 0 or more), the adsorption step is performed in the first adsorption tower 11 in step S20, and when N = 2m + 1 (m is an integer of 0 or more), in step S20, the second An adsorption step is performed in the adsorption tower 12 . That is, when N=0, the adsorption step is performed in the first adsorption tower 11 in step S20.

In step S12, the process control unit 51 causes the other adsorption tower 10 to perform the desorption process. When N = 2m (m is an integer of 0 or more), the desorption step is performed in the second adsorption tower 12 in step S12, and when N = 2m + 1 (m is an integer of 0 or more), in step S12, the 1 adsorption tower 11 performs a desorption step. At this time, the process control unit 51 controls the flow rate controller 30a to supply hydrogen at the hydrogen flow rate mf(n). Thus, when N=2m (m is an integer of 0 or more), the first step is executed (FIGS. 2 and 3), and when N=2m+1 (m is an integer of 0 or more), the second step is executed. (Figs. 2 and 4). When N=0, the desorption step is performed in the second adsorption tower 12 in step S12. When the prediction time n=0, the hydrogen flow rate mf(n) is set in advance as the initial value of the hydrogen flow rate (hydrogen flow rate mf(0)), and the process control unit 51 Hydrogen is supplied so that the flow rate of hydrogen becomes mf(0). As the hydrogen flow rate mf(0), for example, when exhaust gas is supplied from the exhaust gas supply device at a predetermined flow rate and carbon dioxide is adsorbed up to the maximum adsorption amount in the adsorption tower 10, the maximum adsorption amount of carbon dioxide is The time required for adsorption determines the flow rate of hydrogen for desorbing all carbon dioxide.

In step S13, the process control unit 51 determines whether or not the adsorption tower 10 in which the adsorption tower process is being performed is just before carbon dioxide passes through. In this embodiment, the breakthrough of carbon dioxide is determined based on the off-gas temperature at the outlet of the adsorption tower 10 detected by the temperature sensor 84 or the temperature sensor 85 . Since the adsorption reaction in which carbon dioxide is adsorbed by the adsorbent is an exothermic reaction, the offgas temperature rises as the amount of carbon dioxide adsorbed increases. Therefore, carbon dioxide breakthrough can be determined by monitoring the temperature of the off-gas. In the present embodiment, the relationship between the breakthrough of carbon dioxide and the offgas temperature is experimentally investigated in advance, and the offgas temperature immediately before the breakthrough of carbon dioxide is set as a threshold value. When the off-gas temperature detected by the sensor 85 exceeds the threshold, it is determined that carbon dioxide is about to break through. Note that "immediately before breakthrough" is set, for example, within 5 minutes before the breakthrough time. The off-gas temperature in this embodiment is also called "carbon dioxide breakthrough information".

When it is determined in step S13 that carbon dioxide does not pass through (step S13: NO), the process proceeds to step S14. Specifically, when the off-gas temperature detected by the temperature sensor 84 or the temperature sensor 85 is lower than the threshold value, it is determined that carbon dioxide does not pass through.

In step S14, the process control unit 51 determines whether or not the time dt has elapsed since one process started. Steps S13 and S14 are repeated until the time dt elapses, and when the carbon dioxide is just before breakthrough, the process is switched (step S16). The time dt is an interval for predicting a breakthrough time, which will be described later, and is set to, for example, one minute in this embodiment. The time dt can be set arbitrarily.

In step S14, when the time dt has elapsed (step S14: YES), the process control unit 51 sets the predicted time n=n+1 (step S15). In the first step S14, the predicted time n is updated to 1.

In step S30, the breakthrough time prediction unit 52 predicts the breakthrough time t(n), which is the time until carbon dioxide breaks through at the prediction time n=n (current time). In the first step S30, the breakthrough time t(1) at the prediction time n=1 is predicted. The prediction processing of the breakthrough time t(n) will be detailed later.

In step S40, the hydrogen distribution amount determination unit 53 determines the hydrogen distribution amount mf(n) according to the breakthrough time t(n), and the process returns to steps S12 and S20. In the first step S40, the hydrogen flow rate mf(1) is determined. That is, the hydrogen flow rate is updated from the initial value mf(0) of the hydrogen flow rate to mf(1). The process of determining the hydrogen flow rate mf(n) will be described in detail later.

In step S12, the process control unit 51 adjusts the hydrogen flow rate so that it becomes the hydrogen flow rate mf(n) determined in step S40 executed most recently. That is, in the second step S12, the process control unit 51 adjusts the hydrogen flow rate so that it becomes the hydrogen flow rate mf(1). In step S20, the exhaust gas discharged from the exhaust gas supply device is supplied to the adsorption tower 10 as it is without adjusting the flow rate.

In this way, the carbon dioxide recovery control device 50 predicts the breakthrough time t(n) of carbon dioxide in the first adsorption tower 11 every time dt while the first step is being performed, and the prediction result , the hydrogen flow rate mf(n) is updated, and hydrogen is supplied to the second adsorption tower 12 so as to reach the updated hydrogen flow rate mf(n). On the other hand, regardless of the predicted breakthrough time, the temperature at the offgas outlet of the first adsorption tower 11 is used to switch the process immediately before carbon dioxide breaks through in the first adsorption tower 11 . In the second step, as in the first step, the carbon dioxide recovery control device 50 changes the breakthrough time t of carbon dioxide in the second adsorption tower 12 every time dt while the second step is being performed. (n) is predicted, the hydrogen flow rate mf(n) is updated according to the prediction result, and hydrogen is supplied to the first adsorption tower 11 so as to achieve the updated hydrogen flow rate mf(n).

In step S13, if it is determined that the carbon dioxide is just before the breakthrough (step S13: YES), the process proceeds to step S16, the process control unit 51 switches the process, sets N=N+1, and sets step S11. , and the prediction time n is reset to 0 (step S11). That is, when the process is switched, the prediction time n is reset to 0, and the flow rate of hydrogen mf(n) is updated as time elapses in the process being executed (first process or second process). When N=0, the first process is executed as described above, and when N=N+1, N=1, and the process is switched to the second process. If the first process is being executed, the process is switched to the second process in step S16, and if the second process is being executed, the process is switched to the first process in step S16.

(Breakthrough time prediction processing)
FIG. 6 is a flow chart showing the flow of the breakthrough time prediction process S30 in the first embodiment. FIG. 7 is an explanatory diagram for explaining the breakthrough time prediction process.

In step S31, the breakthrough time prediction unit 52 acquires the total exhaust gas amount q(n) [L]. The exhaust gas total amount q(n) is the total amount of exhaust gas that has flowed in from the start of the adsorption process to the predicted time n. As shown in FIGS. 7(b) and 7(c), the total amount of exhaust gas that has flowed in by the predicted time n changes as the predicted time increases. The breakthrough time prediction unit 52 can obtain the total exhaust gas amount q(n) by calculating the integrated value of the measured value [L/s] of the exhaust gas flow rate input from the flow meter 81 every second.

In step S32, the breakthrough time prediction unit 52 acquires the processable exhaust gas amount qc[L]. The treatable flue gas amount qc is the total amount of flue gas that can be treated by the adsorption tower 10 in the adsorption step. Predetermined. As shown in FIG. 7(a), the treatable flue gas amount qc is the total amount of flue gas that has flowed through the adsorption tower 10 until the full amount of carbon dioxide is adsorbed on the adsorbent. In this embodiment, as described above, the processable exhaust gas amount 56 is stored in advance in the storage unit 54 , and the breakthrough time prediction unit 52 acquires the processable exhaust gas amount 56 from the storage unit 54 .

In step S33, the breakthrough time prediction unit 52 acquires the rated exhaust gas amount qf [L/s]. The rated exhaust gas flow rate qf is a predetermined flow rate of exhaust gas for each supply source of exhaust gas, and is stored in advance in the storage unit 54 as the rated exhaust gas flow rate 55 as described above. The breakthrough time prediction unit 52 acquires the rated exhaust gas flow rate 55 from the storage unit 54 .

In step S34, the breakthrough time prediction unit 52 calculates the breakthrough time t(n) using the following equation (2).
t(n)=(qc−q(n))/qf (2)
where t(n): breakthrough time predicted at predicted time n qc: amount of exhaust gas that can be processed in the adsorption process q(n): total amount of exhaust gas that has flowed up to predicted time n qf: rated exhaust gas flow rate

In equation (2), qc-q(n) corresponds to the exhaust gas amount (L) that can be treated in the remaining adsorption process period at predicted time n (FIGS. 7(b) and (c)). Therefore, the breakthrough time t(n) at the predicted time n can be obtained from equation (2). As shown in the figure, the amount of exhaust gas that can be processed at the predicted time n changes (decreases) as time elapses, so the predicted breakthrough time t(n) becomes shorter as time elapses. However, as the exhaust gas flow rate fluctuates, the amount of increase in q(n) also fluctuates, so the amount of decrease in the amount of flue gas that can be processed at predicted time n (qc-q(n)) also fluctuates, and the breakthrough time t ( The amount of decrease in n) also varies.

(Hydrogen distribution amount determination processing)
FIG. 8 is a flow chart showing the flow of the hydrogen distribution amount determination process S40 in the first embodiment.

As shown in FIG. 8, in step S41, the hydrogen flow rate determination unit 53 determines the predicted breakthrough time t(n) at the predicted time n and the predicted time (n−1 ) with the predicted breakthrough time t(n−1).

The relationship between the breakthrough time t(n) and the breakthrough time t(n−1) is
t(n-1)<t(n)+dt ... (first relation)
In the case of , the flow advances to step S42 to decrease the hydrogen flow rate mf(n) from the hydrogen flow rate mf(n-1) set one time ago.

For example, using the amount of exhaust gas that can be processed at predicted time n (qc-q(n)), the amount of carbon dioxide adsorbed by the adsorbent of the adsorption tower 10 is calculated until carbon dioxide breaks through. The hydrogen flow rate mf(n) may be obtained by dividing the amount of hydrogen that is just enough to desorb the carbon dioxide that has been added by the breakthrough time t(n).

When the relationship between the breakthrough time t(n) at the predicted time n and the breakthrough time t(n-1) at the predicted time (n-1) one hour earlier is the first relationship, the adsorption This is the case when the flow rate of exhaust gas flowing into the tower 10 is less than the predicted time (n-1). That is, the time from the start of the step (first step or second step) to the breakthrough of carbon dioxide (adsorption step time) is predicted at the prediction time (n-1) (adsorption step time ), and it is predicted that the time of the process being executed (first process or second process) will become longer. In each step, the desorption step is performed concurrently with the adsorption step and is of equal duration, so longer adsorption steps are expected to result in longer desorption steps. Therefore, by making the hydrogen flow rate mf(n) at the predicted time n smaller than the hydrogen flow rate mf(n-1) at the predicted time (n-1), the amount of hydrogen supplied in the desorption process is excessive. can be prevented from becoming As a result, fluctuations in carbon dioxide concentration in the recovered gas can be suppressed.

The relationship between the breakthrough time t(n) and the breakthrough time t(n−1) is
t(n-1)>t(n)+dt ... (second relation)
In the case of , the process proceeds to step S43 to increase the hydrogen flow rate mf(n) from the hydrogen flow rate mf(n-1) set one time ago.

The hydrogen flow rate mf(n) can be obtained in the same manner as in the case where the relationship between the breakthrough time t(n) and the breakthrough time t(n-1) is the first relationship.

When the relationship between the breakthrough time t(n) and the breakthrough time t(n−1) is the second relationship, the flow rate of the exhaust gas flowing into the adsorption tower 10 is less than the predicted time (n−1). This is the case when there are many. That is, the time from the start of the step (first step or second step) to the breakthrough of carbon dioxide (adsorption step time) is the predicted time (adsorption step time) at the prediction time (n−1). time), and it is predicted that the time of the process being executed (first process or second process) will be shortened. In each step, the desorption step is performed concurrently with the adsorption step and is of equal duration, so shorter adsorption steps are expected to result in shorter desorption steps. Therefore, by making the hydrogen flow rate mf(n) at the predicted time n larger than the hydrogen flow rate (n-1) at the predicted time (n-1), the amount of hydrogen supplied in the desorption process becomes insufficient. can be suppressed. Therefore, in the desorption step, the amount of carbon dioxide remaining in the adsorption tower 10 without being desorbed can be reduced. As a result, fluctuations in carbon dioxide concentration in the recovered gas can be suppressed.

The relationship between the breakthrough time t(n) and the breakthrough time t(n−1) is
t(n-1)=t(n)+dt ... (Third relation)
In the case of , the process proceeds to step S44, where the hydrogen flow rate mf(n) is set to be the same as the hydrogen flow rate mf(n-1) set one time earlier.

When the relationship between the breakthrough time t(n) and the breakthrough time t(n−1) is the third relationship, the flow rate of the exhaust gas flowing into the adsorption tower 10 is equal to the predicted time (n−1). This is the case where they were the same (not changed). That is, the time from the start of the step (first step or second step) to the breakthrough of carbon dioxide (adsorption step time) is predicted at the prediction time (n-1) (adsorption step time ), and the time of the process being executed (either the first process or the second process) is not expected to change. In each step, the desorption step is performed simultaneously with the adsorption step and is of equal duration, so the desorption step is also expected to be unchanged. Therefore, by making the hydrogen flow rate mf(n) at the predicted time n the same as the hydrogen flow rate mf(n-1) at the predicted time (n-1), fluctuations in the carbon dioxide concentration in the recovered gas are suppressed. be able to.

FIG. 9 is an explanatory diagram showing an example of the relationship between the breakthrough time t(n) and the hydrogen flow rate mf(n) in the first embodiment. In this example, the initial value of breakthrough time t(n) is set to 30 [min], the initial value of hydrogen flow rate mf(n) is set to x1 [L/min], and dt is set to 1 [min].

The relationship between the breakthrough time t(n) and the breakthrough time t(n−1) at each predicted time shown in FIG. 9 and the flow rate of hydrogen mf(n) will be described.
At predicted time n=1, breakthrough time t(1)=29, breakthrough time t(0)=30, and dt=1, so
t(1)=t(0)+dt
is. That is, the relationship between breakthrough time t(n) and breakthrough time t(n-1) is the third relationship. for that reason,
mf(1)=mf(0)
and
mf(1)=x1
is set to That is, mf(n) at predicted time n maintains the hydrogen flow rate mf(n-1) at predicted time (n-1).

At predicted time n=2, breakthrough time t(2)=28.5, breakthrough time t(1)=29, and dt=1, so
t(1)<t(2)+dt
is. That is, the relationship between breakthrough time t(n) and breakthrough time t(n-1) is the first relationship. for that reason,
mf(2)=x2 (x2<x1)
is set to That is, mf(n) at predicted time n is made lower than the hydrogen flow rate mf(n-1) at predicted time (n-1).

At predicted time n=3, breakthrough time t(3)=26, breakthrough time t(2)=28.5, and dt=1, so
t(2)>t(3)+dt
is. That is, the relationship between breakthrough time t(n) and breakthrough time t(n-1) is the second relationship. for that reason,
mf(3)=x3(x3>x2)
is set to That is, mf(n) at predicted time n is increased from hydrogen flow rate mf(n-1) at predicted time (n-1).

A program that implements the carbon dioxide recovery control described above may be stored in advance in the carbon dioxide recovery control device 50 . Alternatively, the program may be provided by a program provider via a communication network. Also, the program may be stored in a commercially available and distributed portable storage medium. In this case, the portable storage medium may be set in an external or built-in reading device, and the program may be read and executed by the carbon dioxide recovery control device 50 . Various types of storage media such as CD-ROMs, DVD-ROMs, flexible disks, optical disks, magneto-optical disks, IC cards, and USB memory devices can be used as portable storage media. A program stored in such a storage medium is read by a reader.

As described above, according to the carbon dioxide capture device 200 of the present embodiment, the adsorption step and the desorption step are performed simultaneously in the first step or the second step. That is, in each adsorption tower 10, while the adsorption step is performed in one adsorption tower 10, the desorption step is performed in the other adsorption tower 10, and the step being performed (first step or second There is no waiting period in the process). In addition, in the carbon dioxide recovery device 200, the breakthrough time, which is the time until carbon dioxide breaks through in the adsorption tower 10 in which the adsorption step is performed, is predicted every moment, and according to the prediction result, The flow rate of hydrogen in the adsorption tower 10 in which the desorption process is being performed is updated moment by moment. Since the breakthrough time t(n) is calculated based on the flow rate of the exhaust gas, the adsorption tower functioning as the desorption tower changes according to the fluctuation of the flow rate of the exhaust gas flowing into the adsorption tower 10 functioning as the adsorption tower. It can be said that the amount of hydrogen flowing to 10 is changed. Here, when the flue gas flow rate increases, the hydrogen flow rate is decreased, and when the flue gas flow rate decreases, the hydrogen flow rate is increased. As a result, fluctuations in the concentration of carbon dioxide in the collected gas and fluctuations in the flow rate of the collected gas can be suppressed.

According to the carbon dioxide recovery device 200 of the present embodiment, switching between the first step and the second step is performed immediately before carbon dioxide breaks through in the adsorption tower 10 functioning as an adsorption tower. Therefore, the amount of carbon dioxide discharged as off-gas without being adsorbed by the adsorbent can be suppressed. That is, the recovery rate of carbon dioxide from the exhaust gas by the carbon dioxide recovery device 200 can be improved.

According to the hydrocarbon production apparatus 100 of the present embodiment, as described above, in the carbon dioxide recovery apparatus 200, fluctuations in the concentration of carbon dioxide in the recovered gas and fluctuations in the flow rate of the recovered gas can be suppressed. Therefore, in the hydrocarbon production section 60 that uses the recovered gas to produce a product gas containing methane as a main component, it is possible to suppress a decrease in the purity of methane in the product gas due to fluctuations in the flow rate and concentration of the recovered gas. In addition, it is possible to suppress the deactivation of the hydrocarbon conversion catalyst in the hydrocarbon generation section 60 due to fluctuations in the flow rate of the exhaust gas. Therefore, in the product gas produced in the hydrocarbon production apparatus 100, it is possible to suppress a decrease in methane purity due to fluctuations in the flow rate of the exhaust gas supplied to the hydrocarbon production apparatus 100.

<Second embodiment>
FIG. 10 is an explanatory diagram showing a schematic configuration of a hydrocarbon production apparatus 100A of the second embodiment. A hydrocarbon production device 100A of the second embodiment has a carbon dioxide recovery device 200A in place of the carbon dioxide recovery device 200 in the configuration of the first embodiment. In the embodiments described below, the same components as those of the hydrocarbon production apparatus 100 are denoted by the same reference numerals, and the preceding description is referred to.

The carbon dioxide recovery device 200A has a carbon dioxide concentration sensor 82 and a temperature sensor 83 in addition to the configuration of the carbon dioxide recovery device 200 of the first embodiment. A carbon dioxide concentration sensor 82 and a temperature sensor 83 are provided in the exhaust gas flow path 20 to detect the carbon dioxide concentration in the exhaust gas and the temperature of the exhaust gas, respectively, and output the detection results to the carbon dioxide recovery control device 50 .

Further, the carbon dioxide recovery device 200A of the present embodiment has a carbon dioxide recovery control device 50A instead of the carbon dioxide recovery control device 50. As shown in FIG. In the carbon dioxide recovery control device 50A, the method of predicting the breakthrough time in the breakthrough time prediction unit 52 and the method of calculating the hydrogen flow rate in the hydrogen flow rate determination unit 53 are different from those of the first embodiment. In addition, the storage unit 54 stores a rated carbon dioxide flow rate 57 and a saturated adsorption amount map 58 instead of the rated exhaust gas flow rate 55 and the treatable exhaust gas amount 56 in the first embodiment. The rated carbon dioxide flow rate 57 is the flow rate of carbon dioxide supplied from the exhaust gas supply device, and is predetermined for each exhaust gas supply device. In this embodiment, as the rated carbon dioxide flow rate 57, a value peculiar to the exhaust gas supply device connected to the hydrocarbon production device 100 is input in advance by the user or the like. The saturated adsorption amount map 58 is a map showing the relationship between the carbon dioxide adsorption capacity of the adsorption tower 10 and the flue gas temperature and carbon dioxide concentration. In the embodiment, the relationship between the carbon dioxide adsorption capacity (maximum adsorption amount) in the adsorption tower 10, the exhaust gas temperature, and the carbon dioxide concentration is experimentally investigated in advance, and a map showing the results is stored in the storage unit 54 by the user or the like. is entered in Moreover, it may be stored in advance when the hydrocarbon production apparatus 100A is manufactured.

(Breakthrough time prediction process)
FIG. 11 is a flow chart showing the flow of breakthrough time prediction processing in the second embodiment.

At step S31A, the breakthrough time prediction unit 52 calculates the total amount of carbon dioxide C(n) [L]. The total amount of carbon dioxide C(n) is the total amount of carbon dioxide that has flowed in from the start of the adsorption step to the predicted time n. The breakthrough time prediction unit 52 uses the measured value [L/s] of the exhaust gas flow rate input every second from the flow meter 81 and the measured value of the carbon dioxide concentration input every second from the carbon dioxide concentration sensor 82 to calculate the carbon dioxide per second. By calculating the flow rate [L/s] and calculating the integrated value of the carbon dioxide flow rate [L/s], the total carbon dioxide amount C(n) can be obtained.

At step S32A, the breakthrough time prediction unit 52 acquires the saturated adsorption amount Ca[L]. The saturated adsorption amount Ca is the total amount (maximum adsorption amount) of carbon dioxide that can be adsorbed by the adsorption tower 10 in the adsorption step, and is the exhaust gas temperature (obtained from the temperature sensor 83) and the carbon dioxide concentration (carbon dioxide concentration obtained from the sensor 82) and from the saturated adsorption amount map 58 stored in the storage unit 54.

At step S33A, the breakthrough time prediction unit 52 acquires the rated carbon dioxide flow rate Cf [L/s]. The rated carbon dioxide flow rate Cf is a predetermined flow rate of carbon dioxide for each exhaust gas supply source, and is stored in advance in the storage unit 54 as the rated carbon dioxide flow rate 57 as described above. The breakthrough time prediction unit 52 acquires the rated carbon dioxide flow rate 57 from the storage unit 54 .

At step S34A, the breakthrough time prediction unit 52 calculates the breakthrough time t(n) using the following equation (3).
t(n)=(Ca−C(n))/Cf (3)
However, t(n): Breakthrough time predicted at predicted time n Ca: Saturated adsorption amount C(n): Total amount of carbon dioxide that has flowed up to predicted time n Cf: Rated carbon dioxide flow rate

In equation (3), Ca-C(n) corresponds to the amount of carbon dioxide (L) that can be adsorbed during the remaining adsorption step at predicted time n. Therefore, the breakthrough time t(n) at the predicted time n can be obtained from equation (3). Since the amount of carbon dioxide that can be adsorbed at the predicted time n changes (decreases) with the passage of time, the predicted breakthrough time t(n) becomes shorter with the passage of time. However, as the carbon dioxide flow rate fluctuates, the amount of increase in C(n) also fluctuates. The amount of decrease in t(n) also varies.

In this embodiment, the flow rate, temperature, and carbon dioxide concentration of the exhaust gas are used to predict the breakthrough time t(n). Since the amount of carbon dioxide adsorbed in the adsorption tower 10 varies depending on the flow rate, temperature, and carbon dioxide concentration of the exhaust gas, the breakthrough time can be predicted more accurately than in the first embodiment.

(Hydrogen distribution amount determination processing)
In the second embodiment, the hydrogen distribution amount determining unit 53 calculates the hydrogen distribution amount mf(n) using the following formula (1).

mf(n)=(ma−mp)/t(n) (1)
However, mp: the amount of hydrogen that has flowed through the adsorption tower from the start of the desorption step to the predicted time n, ma: the total amount of hydrogen that can flow through the adsorption tower during the entire period of the desorption step, t(n): Breakthrough time at predicted time n

The amount of hydrogen mp [L] that has flowed through the adsorption tower from the start of the desorption step to the predicted time n can be obtained by integrating the hydrogen flow rate [L/s] that is input every second from the flow controller 30a. can.

In this embodiment, the total amount ma of hydrogen that can flow through the adsorption tower during the entire period of the desorption process is obtained as follows. In the adsorption step performed before the current desorption step, the total amount of carbon dioxide adsorbed in the adsorption tower 10 is determined by the exhaust gas flow rate input from the flow meter 81 and the carbon dioxide input from the carbon dioxide concentration sensor 82. The concentration, the temperature input from the temperature sensor 83, and the saturated adsorption amount map 58 are used to predict and calculate the amount of hydrogen required to desorb all the predicted amount of carbon dioxide adsorption, and the total hydrogen amount ma Let it be [L]. The total hydrogen amount ma does not change even if n is counted up.

The breakthrough time t(n) is the breakthrough time calculated at the predicted time n as described above.

When the temperature and carbon dioxide concentration of the exhaust gas flowing into the adsorption tower 10 change, the saturated adsorption amount of carbon dioxide changes. Specifically, the lower the exhaust gas temperature, the larger the saturated adsorption amount, and the higher the carbon dioxide concentration in the exhaust gas, the larger the saturated adsorption amount. In this embodiment, the hydrogen circulation amount mf(n) is calculated using the total hydrogen amount ma corresponding to the carbon dioxide adsorption amount calculated using the carbon dioxide concentration in the exhaust gas and the exhaust gas temperature, and the hydrogen circulation amount mf(t) is calculated. Therefore, it is possible to set the hydrogen flow rate mf(n) to a more appropriate (neither excess or deficiency) amount for desorbing the carbon dioxide adsorbed inside the adsorption tower 10 . As a result, fluctuations in the flow rate and concentration of the recovered gas can be further suppressed. And the methane purity of the product gas can be further improved.

<Modification of this embodiment>
The present invention is not limited to the above-described embodiments, and can be implemented in various aspects without departing from the scope of the invention. For example, the following modifications are possible. Further, in the above embodiments, part of the configuration realized by hardware may be replaced with software, and conversely, part of the configuration realized by software may be replaced with hardware. may

In the above embodiment, an example was shown in which the breakthrough time t(n) is predicted and the hydrogen flow rate mf(n) is updated a plurality of times in one adsorption step. The breakthrough time may be predicted only once, and the hydrogen flow rate may be determined based on the predicted breakthrough time. For example, at the start of the adsorption step, the exhaust gas flow rate may be used to predict the breakthrough time, and the hydrogen flow rate may be determined according to the predicted breakthrough time. In this way, changes in the flow rate of the recovered gas and the concentration of carbon dioxide can be suppressed compared to the case where the hydrogen flow rate is not changed or the case where the hydrogen flow rate is changed to a predetermined hydrogen flow rate regardless of the breakthrough time. can be done. In particular, when fluctuations in the flue gas flow rate are relatively gentle, fluctuations in the flow rate and concentration of the recovered gas can be appropriately suppressed.

The relationship between the breakthrough time t(n) and the breakthrough time t(n−1) when predicting the breakthrough time t(n) over a plurality of times in one adsorption step in the above embodiment Although an example of the method of determining the hydrogen flow rate mf(n) is shown, the method of determining the hydrogen flow rate mf(n) is not limited to the above embodiment. For example, when t(n−1)<t(n)+dt, the hydrogen flow rate mf(n) is reduced below the hydrogen flow rate mf(n−1), and t(n−1)≧t(n) In the case of +dt, the hydrogen flow rate mf(n) may be maintained (the same as the hydrogen flow rate mf(n−1)). Even in this way, at least, an excessive supply of hydrogen to the adsorption tower 10 can be suppressed.

- The method of calculating the breakthrough time is not limited to the above embodiment. For example, the breakthrough time may be obtained using a map or a relational expression showing the relationship between the exhaust gas flow rate and the breakthrough time. The breakthrough time may be obtained by adding the concentration of carbon dioxide in the exhaust gas and the temperature of the exhaust gas to the flow rate of the exhaust gas, and using a map or relational expression showing the relationship between them and the breakthrough time. Moreover, you may obtain|require by simulation.

The method for determining the flow rate of hydrogen is not limited to the above embodiment. For example, in the formula (1) shown in the second embodiment, the total hydrogen amount ma may be a fixed value. Specifically, assuming that the same amount of carbon dioxide is adsorbed in each step, the amount of hydrogen required to separate the corresponding amount of carbon dioxide may be taken as the total hydrogen amount ma.

In the above embodiment, an example of using the temperature of the off-gas as carbon dioxide breakthrough information, which is information related to carbon dioxide breakthrough, is shown. good. For example, the carbon dioxide concentration in the offgas may be used as the carbon dioxide breakthrough information. Specifically, a carbon dioxide concentration sensor may be provided in the offgas branch channel 23 and the offgas branch channel 24 to detect the outflow of carbon dioxide based on the carbon dioxide concentration in the offgas. Alternatively, the exhaust gas flow rate and the off-gas flow rate may be used as the carbon dioxide breakthrough information. Specifically, a flow meter is provided in the off-gas branch channel 23 and the off-gas branch channel 24, and the difference between the flow rate of the exhaust gas flowing into the adsorption tower 10 and the flow rate of the gas (off-gas) flowing out from the adsorption tower 10 is measured. Carbon efflux may be detected.

- In the above embodiment, the first step and the second step are switched immediately before the carbon dioxide breaks through, but when the carbon dioxide breaks through, the first step and the second step are switched. good too. It is preferable to switch the process immediately before the breakthrough because the carbon dioxide recovery efficiency from the exhaust gas can be improved.

- In the above-described embodiment, an example in which the carbon dioxide recovery device is provided with two adsorption towers is shown, but it may be configured to be provided with three or more adsorption towers.

- In the above-mentioned embodiment, in one adsorption tower, although the adsorption process and the desorption process were made into 1 cycle and multiple cycles were repeatedly performed, another process may be performed further. For example, one cycle may be composed of the adsorption step, the desorption step and the cooling step, or one cycle may be composed of the adsorption step, the preheating step, the desorption step and the cooling step.

- The carbon dioxide recovery apparatus of the above-described embodiment may further include a temperature adjustment unit (for example, a heater, a heat medium, etc.) that adjusts the temperature of the adsorption tower.

- In the above-mentioned embodiment, an example of carbon dioxide recovery control was shown. However, the procedure of hydrocarbon recovery control can be changed in various ways, and the contents of processing in each step may be added/omitted/changed, and the execution order of steps may be changed.

- In the above embodiment, the hydrocarbon production device including the carbon dioxide recovery device and the hydrocarbon generation unit was exemplified, but the carbon dioxide recovery device may be configured as a single unit, or the carbon dioxide recovery control device may be configured as a single unit. good too.

Although the present invention has been described above based on the embodiments and modifications, the above-described embodiments are intended to facilitate understanding of the present invention, and do not limit the present invention. The present invention may be modified and modified without departing from the spirit and scope of the claims, and the present invention includes equivalents thereof. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10... Adsorption tower 11... First adsorption tower 11a, 12a... Adsorbent 12... Second adsorption tower 20... Exhaust gas channel 21, 22... Exhaust gas branch channel 21a... Exhaust gas inlet valve 22a... Exhaust gas inlet valve 23, 24... Offgas branch stream Path 25 Off-gas channel 25a Three-way valve 30 Hydrogen channel 30a Flow controller 31, 32 Hydrogen branch channel 31a, 32a Hydrogen inlet valve 40 Recovered gas channel 41, 42 Recovered gas branch channel 41a, 42a... Recovered gas outlet valve 50, 50A... Carbon dioxide recovery control device 51... Process control unit 52... Breakthrough time prediction unit 53... Hydrogen flow rate determination unit 54... Storage unit 55... Rated exhaust gas flow rate 56... Processable exhaust gas amount 57 Rated carbon dioxide flow rate 58 Saturated adsorption amount map 60 Hydrocarbon generation unit 62 Hydrogen flow path 62a Flow controller 63 Product gas flow path 70 Collected gas tank 72 Collected gas flow path 81 Flow meter 82 Dioxide Carbon concentration sensor 83 Temperature sensor 84 Temperature sensor 85 Temperature sensor 100, 100A Hydrocarbon production device 200, 200A Carbon dioxide recovery device

Claims (9)

A carbon dioxide recovery control device that performs carbon dioxide recovery control to recover carbon dioxide from a mixed gas containing carbon dioxide using a plurality of adsorption towers including at least a first adsorption tower and a second adsorption tower,
A first step of performing an adsorption step of supplying the mixed gas to the first adsorption tower and simultaneously performing a desorption step of supplying hydrogen to the second adsorption tower; and the mixed gas to the second adsorption tower. A process control unit for repeatedly performing a second step of performing an adsorption step of supplying hydrogen at the same time as performing a desorption step of supplying hydrogen to the first adsorption tower;
a breakthrough time prediction unit that predicts a breakthrough time, which is the time from a predetermined prediction time until carbon dioxide leaks out of the adsorption tower, in the adsorption tower in which the adsorption step is performed;
Hydrogen flow for determining the flow rate of hydrogen for controlling the flow rate of hydrogen to be flowed to the adsorption tower in the desorption step being simultaneously performed according to the breakthrough time predicted by the breakthrough time prediction unit. a quantity determination unit;
with
The process control unit
controlling the flow rate of hydrogen to be circulated in the adsorption tower in which the desorption step is performed so as to be the hydrogen flow rate determined by the hydrogen flow rate determining unit;
Acquiring carbon dioxide breakthrough information, which is information on carbon dioxide breakthrough in the adsorption tower in which the adsorption step is being performed, and based on the carbon dioxide breakthrough information, when carbon dioxide breakthrough occurs, or switching between the first step and the second step just before breakthrough of carbon dioxide occurs;
Carbon dioxide capture controller. The carbon dioxide recovery control device according to claim 1,
The breakthrough time prediction unit predicts the breakthrough time every predetermined time,
The hydrogen flow rate determination unit updates the hydrogen flow rate every predetermined time according to the predicted breakthrough time,
When the predetermined time is dt, the predicted time is n (n is an integer of 1 or more), and the breakthrough time predicted at the predicted time n is t(n),
The hydrogen flow rate determining unit,
When the relationship between the breakthrough time t(n) predicted at the prediction time n and the breakthrough time t(n-1) predicted at the prediction time (n-1) is the first relationship, the prediction The hydrogen flow rate at time n is reduced from the hydrogen flow rate at predicted time (n-1), and in the case of the second relationship, the hydrogen flow rate at predicted time n is reduced to predicted time (n-1) , and in the case of the third relationship, the hydrogen flow rate at predicted time n is made the same as the hydrogen flow rate at predicted time (n-1),
the first relationship is t(n−1)<t(n)+dt;
the second relationship is t(n−1)>t(n)+dt;
wherein the third relationship is t(n−1)=t(n)+dt;
Carbon dioxide capture controller. The carbon dioxide recovery control device according to claim 1 or 2,
The hydrogen flow rate determining unit,
Acquiring the amount of hydrogen that has flowed through the adsorption tower from the start of the desorption step to the predicted time, and the total amount of hydrogen that can flow through the adsorption tower during the entire period of the desorption step, Determine the amount of hydrogen to be circulated in the adsorption tower during the desorption step after the predicted time by the following formula (1),
Carbon dioxide capture controller.
mf(n)=(ma−mp)/t(n) (1)
However, mf(n): the amount of hydrogen flowing through the adsorption tower during the desorption process after the predicted time n, mp: the amount of hydrogen flowing through the adsorption tower from the start of the desorption process to the predicted time n, ma : Total amount of hydrogen that can flow through the adsorption tower during the entire period of the desorption process, t(n): Predicted breakthrough time at predicted time n The carbon dioxide recovery control device according to any one of claims 1 to 3,
The breakthrough time prediction unit
In the adsorption step, the total amount of the mixed gas that has flowed into the adsorption tower by the predicted time, the amount of the mixed gas that can be processed in the adsorption step, and the mixed gas predetermined for each supply source of the mixed gas Obtaining the rated mixed gas flow rate, which is the flow rate of, and predicting the breakthrough time by the following formula (2),
Carbon dioxide capture controller.
t(n)=(qc−q(n))/qf (2)
However, t(n): breakthrough time predicted at predicted time n qc: mixed gas amount that can be processed in the adsorption step q(n): total amount of mixed gas that has flowed up to predicted time n qf: rated mixed gas flow rate The carbon dioxide recovery control device according to any one of claims 1 to 3,
The breakthrough time prediction unit
obtaining the flow rate of the mixed gas flowing into the adsorption tower, the temperature of the mixed gas, and the concentration of carbon dioxide in the mixed gas;
In the adsorption step, the total amount of carbon dioxide that has flowed in by the prediction time is calculated using the flow rate of the mixed gas and the concentration of carbon dioxide in the mixed gas,
calculating the saturated adsorption amount of carbon dioxide in the adsorption step using the temperature of the mixed gas at the predicted time and the concentration of carbon dioxide in the mixed gas;
obtaining a rated carbon dioxide flow rate, which is the flow rate of the carbon dioxide predetermined for each supply source of the mixed gas;
Predicting the breakthrough time by the following formula (3),
Carbon dioxide capture controller.
t(n)=(Ca−C(n))/Cf (3)
However, t(n): Breakthrough time predicted at predicted time n Ca: Saturated adsorption amount of carbon dioxide C(n): Total amount of carbon dioxide that has flowed up to predicted time n Cf: Rated carbon dioxide flow rate A carbon dioxide capture device,
A carbon dioxide recovery control device according to any one of claims 1 to 5;
a plurality of adsorption towers capable of separating carbon dioxide from a mixed gas containing carbon dioxide, the plurality of adsorption towers including at least a first adsorption tower and a second adsorption tower;
a mixed gas supply unit capable of supplying the mixed gas to the plurality of adsorption towers;
a hydrogen supply unit capable of supplying hydrogen to the plurality of adsorption towers;
A carbon dioxide capture device. A hydrocarbon production device,
A carbon dioxide capture device according to claim 6;
a hydrocarbon production unit that has a hydrocarbonation catalyst inside and produces a hydrocarbon compound using a recovered gas containing carbon dioxide and hydrogen flowing out of the carbon dioxide recovery device;
Hydrocarbon production equipment. A carbon dioxide recovery method for recovering carbon dioxide from a mixed gas containing carbon dioxide using a plurality of adsorption towers including at least a first adsorption tower and a second adsorption tower,
A first step of performing an adsorption step of supplying the mixed gas to the first adsorption tower and simultaneously performing a desorption step of supplying hydrogen to the second adsorption tower; and the mixed gas to the second adsorption tower. At the same time as performing the adsorption step of supplying the second step of performing the desorption step of supplying hydrogen to the first adsorption tower, repeatedly performing
predicting a breakthrough time, which is the time from a predetermined prediction time until carbon dioxide leaks out of the adsorption tower, in the adsorption tower in which the adsorption step is performed;
determining a flow rate of hydrogen for controlling the flow rate of hydrogen to be flowed to the adsorption tower in the desorption step being simultaneously performed according to the breakthrough time predicted by the breakthrough time prediction unit;
controlling the flow rate of hydrogen to be circulated in the adsorption tower in which the desorption step is performed so as to achieve the determined flow rate of hydrogen;
Acquiring carbon dioxide breakthrough information, which is information on carbon dioxide breakthrough in the adsorption tower in which the adsorption step is being performed, and based on the carbon dioxide breakthrough information, when carbon dioxide breakthrough occurs, or switching between the first step and the second step just before breakthrough of carbon dioxide occurs;
Carbon dioxide recovery method. A program for controlling a carbon dioxide recovery device that recovers carbon dioxide from a mixed gas containing carbon dioxide using a plurality of adsorption towers including at least a first adsorption tower and a second adsorption tower, the program comprising: ,
A first step of performing an adsorption step of supplying the mixed gas to the first adsorption tower and simultaneously performing a desorption step of supplying hydrogen to the second adsorption tower; and the mixed gas to the second adsorption tower. A process control function for repeatedly performing a second step of performing an adsorption step of supplying hydrogen at the same time as performing a desorption step of supplying hydrogen to the first adsorption tower;
A breakthrough time prediction function that predicts a breakthrough time, which is the time from a predetermined prediction time until carbon dioxide leaks out of the adsorption tower, in the adsorption tower in which the adsorption step is performed;
Hydrogen flow for determining the flow rate of hydrogen for controlling the flow rate of hydrogen to be flowed to the adsorption tower in the desorption step being simultaneously performed according to the breakthrough time predicted by the breakthrough time prediction unit. a quantity determination function;
to realize
In the process control function,
controlling the flow rate of hydrogen to be circulated in the adsorption tower in which the desorption step is performed so as to be the hydrogen flow rate determined by the hydrogen flow rate determining unit;
Acquiring carbon dioxide breakthrough information, which is information on carbon dioxide breakthrough in the adsorption tower in which the adsorption step is being performed, and based on the carbon dioxide breakthrough information, when carbon dioxide breakthrough occurs, or switching between the first step and the second step just before breakthrough of carbon dioxide occurs;
program.

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