Adsorbing method of carbon dioxide

Abstract

To absorb carbon dioxide with high efficiency and bring an adsorption volume closer to a target adsorption volume.SOLUTION: A carbon dioxide recovery element comprises: a container body 11 including a plurality of tubes 21, an absorbent 22 that is provided within the tubes 21 and absorbs carbon dioxide, and a plurality of temperature sensors 23 that are provided along the tubes 21; a blow part 13 for delivering an exhaust gas to the container body 11; and a calculation control part 15 for creating an absorption plan of the exhaust gas and controlling the operation of the blow part 13. An absorbing method of carbon dioxide comprises steps of: the calculation control part 15 creating the absorption plan; making the blow part 13 execute delivery of the exhaust gas in the flow based on the absorption plan at the time of the appearance of a peak temperature in the temperature sensor 23; calculating the present total absorption amount of carbon dioxide; and correcting the flow of the exhaust gas to be delivered from the flow part 13 when there is a difference between the present total absorption amount of carbon dioxide and the total absorption amount in the absorption plan.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for adsorbing carbon dioxide in a carbon dioxide capture device. [Background technology]

[0002] In recent years, carbon dioxide capture devices using solid carbon dioxide (CO2) adsorbents such as zeolite have been used. In such carbon dioxide capture devices, the temperature of the adsorbent increases as carbon dioxide is adsorbed, and decreases as carbon dioxide is desorbed.

[0003] Patent Document 1 describes how heat exchange between an adsorption section in which carbon dioxide is adsorbed and an adsorption section in which carbon dioxide is desorbed can be performed to suppress the temperature increase associated with adsorption and the temperature decrease associated with desorption. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-100893 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, when exhaust gas containing carbon dioxide is introduced into a carbon dioxide recovery device to cause saturation adsorption, if the exhaust gas is introduced at a constant flow rate, the amount of adsorption increases linearly up to the amount of carbon dioxide adsorbed Mm at the end of a predetermined time Tm. Once Tm is exceeded, carbon dioxide that has leaked out into the exhaust gas is contained, and the amount of adsorption gradually slows down until it reaches the limit of adsorption.

[0006] In addition, when using a carbon dioxide adsorber, it is unclear how much carbon dioxide is adsorbed in the carbon dioxide adsorber in the initial state. Therefore, depending on the amount of carbon dioxide adsorbed when the carbon dioxide adsorber starts operating, the total adsorption amount may exceed Mm even if the same amount of adsorption is given in the same cycle time as in the model case. In this case, the carbon dioxide adsorber may not be able to adequately adsorb the carbon dioxide in the exhaust gas fed into the carbon dioxide adsorber, and carbon dioxide may leak into the exhaust gas discharged from the carbon dioxide adsorber.

[0007] Furthermore, if the performance of the adsorbent in the carbon dioxide adsorber deteriorates, the carbon dioxide adsorption cannot be sufficiently performed even if exhaust gas is fed into the carbon dioxide adsorber assuming the same amount of adsorption as in the model case. As a result, there is a possibility that carbon dioxide will leak into the exhaust gas discharged from the carbon dioxide adsorber.

[0008] Furthermore, it is known that if the amount of exhaust gas input into the carbon dioxide adsorption device is increased in order to shorten the cycle time, the adsorption amount Mm decreases and carbon dioxide leaks out more quickly into the exhaust gas that is discharged, making it difficult to shorten the cycle time while maintaining the same adsorption amount.

[0009] The present disclosure provides a method for adsorbing carbon dioxide, which performs highly efficient adsorption of carbon dioxide and brings the amount of adsorption close to a target adsorption amount while shortening the cycle time. [Means for solving the problem]

[0010] The carbon dioxide adsorption method disclosed herein comprises a container body provided with a plurality of tubes forming a plurality of paths through which exhaust gas passes, an adsorbent material disposed within the tubes for adsorbing carbon dioxide, and a plurality of temperature sensors disposed continuously along the extending tubes, a blow section for sending exhaust gas containing carbon dioxide to the container body, and an arithmetic and control unit for creating an adsorption plan for a planned cycle time which is a plan for the hourly flow rate of exhaust gas sent out from the blow section and for controlling the operation of the blow section, and the arithmetic and control unit includes the steps of creating the adsorption plan, causing the blow section to send out exhaust gas at a flow rate based on the adsorption plan in accordance with the timing at which a peak in temperature acquired by the temperature sensor appears, calculating the current total amount of carbon dioxide adsorption, and correcting the flow rate of exhaust gas sent out from the blow section when a difference occurs between the current total amount of carbon dioxide adsorption and the total amount of carbon dioxide adsorption according to the adsorption plan, by the arithmetic and control unit. This makes it possible to control the flow rate of exhaust gas sent from the blow section to the container body which adsorbs carbon dioxide based on the adsorption plan, and to correct the flow rate of exhaust gas sent from the blow section if a difference occurs between the adsorption plan and the actual amount of adsorption. Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a carbon dioxide adsorption method that can perform carbon dioxide adsorption with high efficiency, shorten the cycle time, and bring the adsorption amount closer to a target adsorption amount. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing a configuration example of a carbon dioxide capture device according to the first embodiment. [Diagram 2] FIG. 4 is a diagram showing an example of an operation flow of the carbon dioxide capture device according to the first embodiment. [Diagram 3] FIG. 11 is a diagram showing an example of changing the amount of adsorption of carbon dioxide for each hour according to the peak time of the temperature sensor and the adsorption plan according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] First embodiment Hereinafter, the configuration of the carbon dioxide recovery device 1 according to the present embodiment will be described with reference to the drawings. As shown in Fig. 1, the carbon dioxide recovery device 1 includes a container body 11, an exhaust gas inlet pipe 12 for introducing exhaust gas into the container body 11, a blow unit 13 for changing the amount of exhaust gas introduced per time into the container body 11 via the exhaust gas inlet pipe 12, and an exhaust gas outlet pipe 14 for discharging exhaust gas from the container body 11. For ease of explanation, the description will be given assuming that the blow unit 13 and the exhaust gas inlet pipe 12 are arranged below, the exhaust gas outlet pipe 14 and the calculation control unit 15 are arranged above, and the container body 11 is arranged between the exhaust gas inlet pipe 12 and the exhaust gas outlet pipe 14, as shown in Fig. 1.

[0014] The container body 11 includes a tube 21 through which exhaust gas introduced from the exhaust gas inlet pipe 12 flows, an adsorbent 22 provided within the tube 21 for adsorbing carbon dioxide, a plurality of temperature sensors 23 provided throughout the adsorbent 22, and a refrigerant pipe 24 through which a refrigerant flows.

[0015] 1, a plurality of tubes 21 extending from the bottom to the top are provided inside the container body 11. That is, the plurality of tubes 21 are paths through which the exhaust gas entering from the exhaust gas inlet pipe 12 is divided and arranged in parallel, and flows toward the exhaust gas outlet pipe 14. An adsorbent 22 that adsorbs carbon dioxide is provided inside each of the plurality of tubes 21. The range in the vertical direction within which the adsorbent 22 is provided inside the tubes 21 is defined as the container length L (mm) of the container body 11.

[0016] 1, n (n is a natural number of 2 or more) temperature sensors 23 are continuously arranged at a pitch interval P (mm) in the vertical direction along each of the tubes 21 extending in the vertical direction. Here, seven temperature sensors 23 are arranged at equal intervals in the vertical direction. Also, although the temperature sensor 23 is shown in only one tube 21 in FIG. 1, the other tubes 21 may also be provided with temperature sensors 23 in the same manner.

[0017] The adsorbent 22 may be a solid adsorbent such as zeolite that adsorbs carbon dioxide.

[0018] A thermocouple may be used as the temperature sensor 23. The temperature sensor 23 outputs acquired temperature information to the calculation control unit 15. The temperature sensors 23 will be described assuming that the one provided at the top (most downstream) in the tube 21 is the first temperature sensor 23a and the one provided at the bottom (most upstream) is the seventh temperature sensor 23g, and that they are numbered consecutively. For example, the temperature of the adsorbent 22 acquired by the first temperature sensor 23a is T1, and the same applies to the other temperature sensors 23b to 23g.

[0019] 1, refrigerant pipes 24 can be arranged to sandwich each of the multiple tubes 21. The refrigerant pipes 24 can cool the adsorbent 22 by passing a refrigerant supplied from a refrigerant supply source (not shown) provided on the outside of the container body 11 through the refrigerant pipes 24 to cool the tubes 21.

[0020] The exhaust gas inlet pipe 12 is equipped with a switching valve (not shown) provided near the connection portion with the container body 11. The exhaust gas inlet pipe 12 is provided between the container body 11 and the blow section 13, and is a path through which exhaust gas flows from the blow section 13 to the container body 11.

[0021] The open / close state of the switching valve is controlled by, for example, the calculation control unit 15. In this way, the switching valve can adjust the amount of exhaust gas input into the tube 21 of the container body 11.

[0022] The blow unit 13 sends out exhaust gas containing carbon dioxide toward the container body 11 through the exhaust gas inlet pipe 12. Here, the blow unit 13 can adjust the flow rate of the exhaust gas sent out in accordance with the control from the calculation control unit 15. In particular, the blow unit 13 can adjust the flow rate of the exhaust gas in accordance with switching of the SV (Space Velocity) value, which is set by the calculation control unit 15 and is an index of how many times the container volume of gas volume is flowed per hour.

[0023] The exhaust gas outlet pipe 14 is a path for discharging the exhaust gas after the carbon dioxide has been removed by adsorption of the carbon dioxide in the container body 11.

[0024] The calculation control unit 15 controls the amount of exhaust gas flowing from the blow unit 13 to the container body 11 based on the plan of the amount of carbon dioxide adsorption and the adsorption plan of the amount of carbon dioxide adsorption in the planned cycle time, i.e., the creation of a plan of what amount of carbon dioxide to adsorb at what time, and the timing of the appearance of the temperature peak acquired by the temperature sensor 23 and the information of the adsorption plan. Furthermore, the calculation control unit 15 calculates the total amount of carbon dioxide adsorption in the container body 11, and performs additional control to correct the amount of exhaust gas flowing from the blow unit 13 to the container body when there is a difference in the amount of carbon dioxide adsorption from the adsorption plan. As described above, the calculation control unit 15 can control not only the operation of the blow unit 13 but also the operation of the switching valve.

[0025] Here, the principle of the carbon dioxide recovery device 1 will be explained. In the container body 11, the temperature of the adsorbent 22 needs to be lowered when adsorbing carbon dioxide, and the temperature is lowered by circulating a refrigerant through the refrigerant pipes 24 around each tube 21. Here, when the temperature change up to saturated adsorption is monitored using the temperature sensor 23, a temperature peak appears for each layer in the order in which carbon dioxide is adsorbed by the adsorbent 22. This is because the temperature rises at the moment of adsorption, but the heat is immediately taken away by the refrigerant, and this appears in the form of a temperature peak. From the time of this temperature peak and the pitch of the temperature sensor 23, the adsorption speed and the extent to which carbon dioxide has been adsorbed within the container body 11 can be determined from the outside.

[0026] Next, the operation of the carbon dioxide capture device 1 will be described with reference to the flow chart shown in FIG.

[0027] The calculation control unit 15 determines the amount of carbon dioxide adsorption (step S1). Here, the calculation control unit 15 sets the amount of carbon dioxide adsorption in the cycle time from the start to the end of carbon dioxide adsorption. Note that this amount of carbon dioxide adsorption is set to an amount less than the amount of carbon dioxide desorption.

[0028] Next, the calculation control unit 15 creates an adsorption plan (step S2). That is, the calculation control unit 15 creates a route diagram of the amount of carbon dioxide adsorption in the planned cycle time. This makes it possible to plan how much carbon dioxide is adsorbed at what time. Now, with reference to FIG. 3, an example of change control of the amount of carbon dioxide adsorption per hour according to the adsorption plan planned by the calculation control unit 15 will be described. Here, two types of plans, plan A and plan B, are shown as examples.

[0029] Plan A: First, exhaust gas is introduced into the container body 11 from the blow unit 13 at SV600, and when the temperature of the adsorbent 22 measured by the fourth temperature sensor 23d peaks, the setting is switched to SV500. After that, when the temperature peaks at the third temperature sensor 23c, the setting is switched to SV400, and at time Ts2, which is the point at which the temperature peaks at the second temperature sensor 23b, the setting is switched to the same SV400 as before.

[0030] In this case, at the peak time Ts2 of the second temperature sensor 23b, the maximum adsorption amount is Mm, which is the same as the conventional case. In this way, in the carbon dioxide capture device 1, the cycle time can be shortened and the adsorption amount of carbon dioxide can be increased.

[0031] Plan B: First, exhaust gas is introduced into the container body 11 from the blow unit 13 at SV800, and when the temperature of the adsorbent 22 measured by the fifth temperature sensor 23d reaches a peak, the setting is switched to SV400. After that, when the temperature measured by the third temperature sensor 23c reaches a peak, the setting is switched to SV200.

[0032] By doing this, at cycle time Ts2, the SV200 is in a state in which exhaust gas flows in more slowly than the conventional SV400, so the total amount of carbon dioxide adsorption Mm2 at the leakage limit is greater than the conventional total amount of adsorption Mm.

[0033] Next, the calculation control unit 15 performs a feedback process by comparing the planned adsorption plan with the actual data (step S3). That is, the calculation control unit 15 controls the operation of the blow unit 13 so as to obtain the SV value based on the adsorption plan, using the timing at which each temperature sensor 23 appears as an input value.

[0034] Furthermore, the calculation and control unit 15 calculates the total adsorption amount of carbon dioxide. Here, when there is a difference between the current total adsorption amount of carbon dioxide and the total adsorption amount of carbon dioxide in the adsorption plan, the calculation and control unit 15 performs additional control to correct the SV value and operate the blow unit 13.

[0035] The blower 13 sends out the exhaust gas to the vessel body 11 while adjusting the SV value, i.e., the flow velocity and flow rate of the exhaust gas, according to the control of the calculation control unit 15 in step S3 (step S4). In the carbon dioxide recovery device 1, the exhaust gas after the carbon dioxide is adsorbed in the vessel body 11 is discharged through the exhaust gas outlet pipe 14.

[0036] Thereafter, when the scheduled cycle time is reached (Yes in step S5), the carbon dioxide recovery device 1 ends the process. If the scheduled cycle time is not reached (No in step S5), the process returns to step S3 and the process is repeated while adjusting the flow rate of the inflowing exhaust gas by feedback control.

[0037] As a result, in the carbon dioxide recovery device 1, carbon dioxide can be sufficiently adsorbed in the container body 11, increasing the amount of adsorption, and the cycle time can be shortened without carbon dioxide leaking in the exhaust gas discharged from the container body 11.

[0038] Moreover, by suppressing the SV value at the time Ts2 as in the above-mentioned plan B, it is possible to adsorb a larger total amount of carbon dioxide than that adsorbed by the conventional method.

[0039] Furthermore, in the carbon dioxide recovery device 1, the calculation and control unit 15 can correct the flow rate of the exhaust gas discharged from the blow unit 13, i.e., correct the SV value, depending on the difference between the actual carbon dioxide adsorption state and the adsorption plan, so that the target carbon dioxide adsorption amount can be approached even if the adsorbent 22 has deteriorated.

[0040] Furthermore, since the carbon dioxide recovery device 1 uses the difference between the actual carbon dioxide adsorption state and the adsorption plan for control, it is possible to approach the target adsorption amount even if the carbon dioxide concentration of the exhaust gas fluctuates. That is, since the calculation and control unit 15 uses the heat generation phenomenon of the adsorbent 22, when the carbon dioxide concentration of the exhaust gas input to the container body 11 decreases, the time until the temperature peak occurs is extended, and therefore it is possible to instruct the blow unit 13 to increase the SV value. Conversely, when the carbon dioxide concentration of the input exhaust gas increases, the calculation and control unit 15 performs control to decrease the SV value, thereby eliminating the difference with the adsorption plan and making it possible to approach the target adsorption amount.

[0041] Furthermore, by monitoring the carbon dioxide concentration of the exhaust gas input and the difference in the adsorption amount of the adsorption plant, it is possible to diagnose deterioration of the adsorbent 22, which can lead to preventive maintenance such as scheduled replacement of the adsorbent.

[0042] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention. [Explanation of symbols]

[0043] 1 Carbon dioxide capture device 11 Container body 12 Exhaust gas inlet pipe 13 Blow section 14 Exhaust gas outlet pipe 15 Calculation control unit 21 Tube 22 Adsorbents 23 Temperature Sensor 24 Refrigerant pipe

Claims

[Claim 1] a plurality of tubes forming a plurality of paths through which exhaust gas passes; An adsorbent material disposed within the tube for adsorbing carbon dioxide; A container body provided with a plurality of temperature sensors arranged continuously along the extending tube; A blower that delivers exhaust gas containing carbon dioxide to the container body; A method for adsorbing carbon dioxide in a carbon dioxide recovery unit, comprising: creating an adsorption plan for a planned cycle time, which is a plan for the flow rate of exhaust gas sent out from the blow unit per hour; and controlling an operation of the blow unit; The arithmetic and control unit creating the adsorption plan; A step of causing the blow unit to deliver exhaust gas at a flow rate based on the adsorption plan in response to a timing when a peak in the temperature acquired by the temperature sensor appears; Calculating the total amount of carbon dioxide adsorption in the current state; and a step of correcting a flow rate of the exhaust gas discharged from the blow unit when there is a difference between a current total adsorption amount of carbon dioxide and a total adsorption amount of carbon dioxide according to the adsorption plan. Carbon dioxide adsorption method.

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