Methods for adsorbing 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 recovery device.

Background Art

[0002] In recent years, carbon dioxide recovery devices using solid adsorbents for carbon dioxide (CO2) such as zeolite have been utilized. In such a carbon dioxide recovery device, the temperature of the adsorbent rises due to the adsorption of carbon dioxide, and the temperature of the adsorbent decreases due to the desorption of carbon dioxide.

[0003] Patent Document 1 describes suppressing the temperature rise associated with adsorption and suppressing the temperature decrease associated with desorption by performing heat exchange between an adsorption section where carbon dioxide adsorption is occurring and an adsorption section where desorption is occurring.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, when introducing an exhaust gas containing carbon dioxide into a carbon dioxide recovery device to perform saturated adsorption, if the exhaust gas is introduced at a constant flow rate, the adsorption amount linearly increases up to the carbon dioxide adsorption amount Mm when a predetermined time Tm has elapsed. When exceeding Tm, carbon dioxide leaking into the exhaust gas is included, and the adsorption amount gradually slows down and reaches the limit amount of adsorption.

[0006] Furthermore, when using a carbon dioxide adsorbent, it is unknown how much carbon dioxide is adsorbed by the adsorbent in its initial state. Therefore, depending on the amount of carbon dioxide adsorbed at the start of operation of the carbon dioxide adsorbent, the total adsorbed amount may exceed Mm even if the same adsorption rate is applied with the same cycle time as the model case. In this case, the carbon dioxide adsorbent may not be able to adequately adsorb the carbon dioxide in the exhaust gas fed into the adsorbent, and carbon dioxide may leak into the exhaust gas discharged from the carbon dioxide adsorbent.

[0007] Furthermore, if the performance of the adsorbent material in the carbon dioxide adsorber deteriorates, even if the same amount of exhaust gas as in the model case is introduced into the carbon dioxide adsorber, sufficient carbon dioxide adsorption may not be possible. As a result, there is a possibility that carbon dioxide may leak into the exhaust gas emitted from the carbon dioxide adsorber.

[0008] Furthermore, it has been found that increasing the amount of exhaust gas fed into the carbon dioxide adsorber to shorten the cycle time reduces the adsorption capacity Mm, causing carbon dioxide to leak into the exhaust gas more quickly. Therefore, it is difficult to shorten the cycle time while maintaining the same adsorption capacity.

[0009] This disclosure provides a method for adsorbing carbon dioxide that achieves high efficiency, shortens cycle time, and brings the adsorption amount closer to the target adsorption amount. [Means for solving the problem]

[0010] The carbon dioxide adsorption method according to this disclosure comprises a container body provided with a plurality of tubes forming a plurality of paths through which exhaust gas passes, an adsorbent disposed in the tubes for adsorbing carbon dioxide, and a plurality of temperature sensors continuously arranged along the extending tubes; a blow section that delivers exhaust gas containing carbon dioxide to the container body; and a calculation control unit that creates an adsorption plan in a planned cycle time, which is a plan of the hourly flow rate of the exhaust gas delivered from the blow section, and controls the operation of the blow section, wherein the calculation control unit comprises the steps of: creating the adsorption plan; causing the blow section to deliver exhaust gas at a flow rate based on the adsorption plan in accordance with the timing of the appearance of a temperature peak acquired by the temperature sensors; calculating the current total amount of carbon dioxide adsorbed; and correcting the flow rate of exhaust gas delivered from the blow section if there is a difference between the current total amount of carbon dioxide adsorbed and the total amount of carbon dioxide adsorbed according to the adsorption plan. This allows for the control of the flow rate of exhaust gas sent from the blowdown section to the container body that adsorbs carbon dioxide, based on the adsorption plan, and also allows for correction of the flow rate of exhaust gas sent from the blowdown section if there is a difference between the adsorption plan and the actual adsorption amount. [Effects of the Invention]

[0011] This disclosure provides a method for adsorbing carbon dioxide that achieves high efficiency, shortens the cycle time, and brings the adsorption amount closer to the target adsorption amount. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example configuration of a carbon dioxide capture device according to Embodiment 1. [Figure 2] This figure shows an example of the operation flow of a carbon dioxide capture device according to Embodiment 1. [Figure 3] This figure shows an example of how to change the amount of carbon dioxide adsorbed per hour according to the peak time of the temperature sensor and the adsorption plan according to Embodiment 1. [Modes for carrying out the invention]

[0013] Embodiment 1 The configuration of the carbon dioxide recovery unit 1 according to this embodiment will now be described with reference to the drawings. As shown in Figure 1, the carbon dioxide recovery unit 1 comprises a container body 11, an exhaust gas inlet pipe 12 for introducing exhaust gas into the container body 11, a blower unit 13 that changes the amount of exhaust gas introduced into the container body 11 per unit of time via the exhaust gas inlet pipe 12, and an exhaust gas outlet pipe 14 for discharging exhaust gas from the container body 11. For the sake of simplicity, as shown in Figure 1, the blower unit 13 and the exhaust gas inlet pipe 12 are located at the bottom, the exhaust gas outlet pipe 14 and the calculation control unit 15 are located at the top, and the container body 11 is located between the exhaust gas inlet pipe 12 and the exhaust gas outlet pipe 14.

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

[0015] As shown in Figure 1, the container body 11 is provided with multiple tubes 21 extending from bottom to top. In other words, the multiple tubes 21 are the paths through which the exhaust gas entering from the exhaust gas inlet pipe 12 is divided and arranged in parallel, and then flows toward the exhaust gas outlet pipe 14. Inside each of the multiple tubes 21, there is an adsorbent material 22 that adsorbs carbon dioxide. The vertical range within the tubes 21 where the adsorbent material 22 is provided is defined as the container length L (mm) of the container body 11.

[0016] Furthermore, as shown in FIG. 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 respective tubes 21 extending in the vertical direction. Here, it is assumed that seven temperature sensors 23 are arranged at equal intervals in the vertical direction. Also, in FIG. 1, only one tube 21 is shown with the temperature sensor 23, but the temperature sensor 23 can be provided in the same manner in other tubes 21 as well.

[0017] As the adsorbent 22, a solid adsorbent such as zeolite that adsorbs carbon dioxide can be used.

[0018] A thermocouple can be used for the temperature sensor 23. The temperature sensor 23 outputs the acquired temperature information to the arithmetic control unit 15. Note that, in the tube 21, the temperature sensor 23 provided at the upper part (the most downstream) is regarded as the first temperature sensor 23a, and the temperature sensor 23 provided at the lower part (the most upstream) is regarded as the seventh temperature sensor 23g, and they will be described as being in consecutive numbers. For example, let the temperature of the adsorbent 22 acquired by the first temperature sensor 23a be T1, and the same applies to the other temperature sensors 23b to 23g.

[0019] Also, as shown in FIG. 1, the refrigerant pipe 24 can be arranged so as to sandwich each of the plurality of tubes 21. The refrigerant pipe 24 can cool the adsorbent 22 by passing the refrigerant supplied from a refrigerant supply source (not shown) provided outside the container body 11 and cooling the tube 21.

[0020] The exhaust gas inlet pipe 12 includes 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 blower portion 13 and is the path for the exhaust gas to flow from the blower portion 13 into the container body 11.

[0021] The switching valve is controlled to be opened or closed, for example, by the arithmetic control unit 15. Thereby, the switching valve can adjust the amount of exhaust gas introduced into the tube 21 of the container body 11.

[0022] The blowing section 13 sends out exhaust gas containing carbon dioxide toward the container main body 11 through the exhaust gas inlet pipe 12. Here, the blowing section 13 can adjust the flow rate of the exhaust gas to be sent out according to the control from the arithmetic control section 15. In particular, in the blowing section 13, the flow rate of the exhaust gas can be adjusted according to the switching of the SV (Space Velocity) value, which is an index of how many times the gas volume of the container volume flows per hour and is set by the arithmetic control section 15.

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

[0024] The arithmetic control section 15 creates an operation for planning the amount of carbon dioxide to be adsorbed, an adsorption plan for the amount of carbon dioxide adsorbed in the planned cycle time, that is, a plan for how much carbon dioxide to adsorb at any time, and controls the amount of exhaust gas flowing from the blowing section 13 to the container main body 11 based on the timing when the peak of the temperature acquired by the temperature sensor 23 appears and the information of the adsorption plan. Furthermore, in the arithmetic control section 15, when calculating the total adsorption amount of carbon dioxide in the container main body 11 and there is a difference in the carbon dioxide adsorption amount with respect to the adsorption plan, additional control is performed to correct the amount of exhaust gas flowing from the blowing section 13 to the container main body. As described above, the arithmetic control section 15 can control not only the operation of the blowing section 13 but also the operation of the switching valve.

[0025] Here, we will explain the principle of carbon dioxide recovery unit 1. In the container body 11, the temperature of the adsorbent material 22 needs to be lowered when carbon dioxide is adsorbed, and this is achieved by circulating refrigerant through refrigerant pipes 24 around each tube 21. When the temperature change until saturation adsorption is monitored using the temperature sensor 23, temperature peaks appear in each layer in the order in which carbon dioxide is adsorbed onto the adsorbent material 22. This is because the temperature rises at the moment of adsorption, but the heat is immediately removed by the refrigerant, resulting in a temperature peak. From the time of this temperature peak and the pitch of the temperature sensor 23, the adsorption rate and how much of the container body 11 has been adsorbed can be determined from the outside.

[0026] Next, the operation of the carbon dioxide capture unit 1 will be explained with reference to the flowchart shown in Figure 2.

[0027] The calculation control unit 15 determines the amount of carbon dioxide to be adsorbed (step S1). Here, the calculation control unit 15 sets the amount of carbon dioxide adsorbed during the cycle time from the start to the end of carbon dioxide adsorption. This amount of carbon dioxide adsorbed is less than the amount of carbon dioxide desorbed.

[0028] Next, the calculation control unit 15 creates an adsorption plan (step S2). That is, the calculation control unit 15 creates a path diagram of the amount of carbon dioxide adsorbed during the planned cycle time. This allows it to plan how much carbon dioxide to adsorb at what time. Referring to Figure 3, an example of controlling the change in the amount of carbon dioxide adsorbed per hour according to the adsorption plan planned by the calculation control unit 15 will be explained. Two types, Plan A and Plan B, will be shown as examples.

[0029] Plan A: First, exhaust gas is introduced into the container body 11 from the blow section 13 using SV600. When the temperature of the adsorbent 22, measured by the fourth temperature sensor 23d, reaches a peak, the setting is switched to SV500. Subsequently, when the temperature peak is reached by the third temperature sensor 23c, the setting is switched to SV400, and at time Ts2, which is the point where the temperature peak is reached by the second temperature sensor 23b, the setting is set to SV400, the same as before.

[0030] In this case, at Ts2, which is the peak time of the second temperature sensor 23b, the maximum adsorption amount is also the same as in the conventional case, Mm. By doing so, the carbon dioxide capture unit 1 can shorten the cycle time and increase the amount of carbon dioxide adsorbed.

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

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

[0033] Next, the calculation control unit 15 compares the planned adsorption plan with the actual data and performs feedback processing (step S3). That is, the calculation control unit 15 uses the timing of the appearance of each temperature sensor 23 as input values ​​and controls the operation of the blow unit 13 so that the SV value is based on the adsorption plan.

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

[0035] The blowdown section 13 adjusts the SV value, i.e., the flow velocity and flow rate of the exhaust gas, in accordance with the control of the calculation control section 15 in step S3, and sends the exhaust gas to the container body 11 (step S4). In the carbon dioxide recovery unit 1, the exhaust gas after carbon dioxide has been adsorbed in the container body 11 is discharged through the exhaust gas outlet pipe 14.

[0036] Subsequently, carbon dioxide capture unit 1 terminates processing once the scheduled cycle time is reached (Yes in step S5). If the scheduled cycle time has not been reached (No in step S5), the process returns to step S3 and is repeated while adjusting the flow rate of the incoming exhaust gas through feedback control.

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

[0038] Furthermore, as described in Plan B above, by suppressing the SV value at Ts2, it is possible to adsorb more carbon dioxide than the total adsorption amount achieved by conventional methods.

[0039] Furthermore, the carbon dioxide recovery unit 1 can correct the flow rate of exhaust gas sent from the blowdown unit 13, i.e., correct the SV value, from the calculation control unit 15 according to the difference between the actual carbon dioxide adsorption state and the adsorption plan. Therefore, even if the adsorbent material 22 deteriorates, it is possible to approach the target amount of carbon dioxide adsorbed.

[0040] Furthermore, since the carbon dioxide recovery unit 1 uses control based on the difference between the actual carbon dioxide adsorption state and the adsorption plan, it can approach the target adsorption amount even if the carbon dioxide concentration of the exhaust gas fluctuates. Specifically, since the calculation control unit 15 utilizes the heat generation phenomenon of the adsorbent material 22, if the carbon dioxide concentration of the exhaust gas introduced into the container body 11 decreases, the time until the temperature peak occurs is extended, allowing the unit to instruct the blowdown section 13 to increase the SV value. Conversely, if the carbon dioxide concentration of the introduced exhaust gas increases, the calculation control unit 15 controls the SV value to decrease, thereby eliminating the difference with the adsorption plan and bringing the unit closer to the target adsorption amount.

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

[0042] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. In other words, the above description has been omitted and simplified as appropriate for the sake of clarity, and those skilled in the art can easily change, add, and modify each element of the embodiments 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. Arithmetic Control Unit 21 Tubes 22 Adsorbent 23 Temperature Sensor 24 Refrigerant pipes

Claims

[Claim 1] Multiple tubes that form multiple paths through which exhaust gas passes, An adsorbent material that adsorbs carbon dioxide is placed inside the tube, A container body provided with a plurality of temperature sensors arranged continuously along the extending tube, The container body is provided with a blower section for delivering exhaust gas containing carbon dioxide, A carbon dioxide recovery method for carbon dioxide, comprising a calculation control unit that creates an adsorption plan in a planned cycle time, which is a plan of the hourly flow rate of exhaust gas discharged from the blow-off section, and controls the operation of the blow-off section, The calculation control unit, The steps include creating the aforementioned adsorption plan, The steps include: causing the blower to deliver exhaust gas at a flow rate based on the adsorption plan, in accordance with the timing at which a temperature peak obtained by the temperature sensor appears; The steps include: calculating the total amount of carbon dioxide adsorbed in the current situation, The system includes a step of correcting the flow rate of exhaust gas discharged from the blowdown section when there is a difference between the total amount of carbon dioxide adsorbed in the current state and the total amount of carbon dioxide adsorbed by the adsorption plan. Methods for adsorbing carbon dioxide.

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