Carbon dioxide capture equipment and carbon dioxide capture method

Abstract

To recover high-concentration carbon dioxide from exhaust gas and furthermore to suppress increase in an installation area and cost of equipment.SOLUTION: Carbon dioxide recovery equipment comprises: an adsorption tower filled with a carbon dioxide absorbing substance; a suction machine which vacuum-suctions the inside of the adsorption tower; a delivery line connected to a delivery port of the suction machine; a carbon dioxide recovery line connected to the delivery line; a recovery gas valve provided in the carbon dioxide recovery line; a non-recovery gas line connected to the delivery line; a non-recovery gas valve provided in the non-recovery gas line; and a control device. The control device closes the recovery gas valve and opens the non-recovery gas valve when the pressure in the adsorption tower is low vacuum on the basis of the predetermined recovery pressure, and closes the non-recovery gas valve and opens the recovery gas valve when the pressure in the adsorption tower is high vacuum on the basis of the recovery pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to carbon dioxide recovery equipment and a carbon dioxide recovery method.

Background Art

[0002] From the perspective of global environmental conservation, equipment for recovering carbon dioxide contained in exhaust gas has been studied to reduce the amount of carbon dioxide emissions.

[0003] As equipment for recovering carbon dioxide from exhaust gas, for example, there is the equipment disclosed in Non-Patent Document 1 below. This equipment includes a blower, a dehumidifier, a first adsorption tower, a first suction machine, a second adsorption tower, and a second suction machine. The blower sends exhaust gas to the dehumidification tower. The dehumidification tower removes moisture in the exhaust gas. The first adsorption tower and the second adsorption tower are filled with an adsorbent capable of adsorbing carbon dioxide inside. The first adsorption tower adsorbs carbon dioxide in the exhaust gas that has passed through the dehumidifier. The first suction machine vacuum-sucks the inside of the first adsorption tower to separate carbon dioxide from the adsorbent in the first adsorption tower, and sends the gas containing this carbon dioxide to the second adsorption tower. The second adsorption tower adsorbs carbon dioxide in the gas from the first adsorption tower via the first suction machine. The second suction machine vacuum-sucks the inside of the second adsorption tower to separate carbon dioxide from the adsorbent in the second adsorption tower, and sends the gas containing this carbon dioxide to the tank. In addition, in order to continuously process exhaust gas, both the first adsorption tower and the second adsorption tower need to exist in a plurality of units.

[0004] In this equipment, since carbon dioxide adsorption is performed in two stages, high-concentration carbon dioxide can be recovered.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] The equipment described in Non-Patent Document 1 includes a first-stage adsorption tower, a first suction unit, a second-stage adsorption tower, and a second suction unit to recover high concentrations of carbon dioxide. As a result, the equipment described in Non-Patent Document 1 has a large number of components, which increases the installation area and the equipment cost.

[0007] Therefore, the purpose of this disclosure is to provide a carbon dioxide recovery system and a carbon dioxide recovery method that can recover high concentrations of carbon dioxide from exhaust gas while suppressing increases in the installation area and equipment costs. [Means for solving the problem]

[0008] A carbon dioxide recovery device as a first embodiment of the invention for achieving the above objective is: A carbon dioxide recovery facility capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide comprises: an adsorption tower filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure; a blower that sends the exhaust gas into the adsorption tower; a suction machine that vacuums the inside of the adsorption tower; a discharge line connected to the discharge port of the suction machine; a carbon dioxide recovery line connected to the discharge line; a recovery gas valve provided in the carbon dioxide recovery line; a non-recovery gas line connected to the discharge line; a non-recovery gas valve provided in the non-recovery gas line; and a control device that closes the recovery gas valve and opens the non-recovery gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum with respect to a predetermined recovery pressure, and closes the non-recovery gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum with respect to the recovery pressure. The control device includes a pressure gauge capable of detecting the pressure inside the adsorption tower, a valve controller that controls the opening and closing of the recovery gas valve and the non-recovery gas valve based on the pressure detected by the pressure gauge, and a suction machine controller that controls the operation of the suction machine based on the pressure detected by the pressure gauge. The suction machine controller operates the suction machine to increase its suction force when the pressure detected by the pressure gauge is higher than the recovery pressure and closer to the recovery pressure than atmospheric pressure, or when it becomes a suction force change pressure which is the recovery pressure. , A second embodiment of the invention for achieving the above objective is a carbon dioxide recovery system, A carbon dioxide recovery facility capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide comprises: an adsorption tower filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure; a blower that sends the exhaust gas into the adsorption tower; a suction machine that vacuums the inside of the adsorption tower; a discharge line connected to the discharge port of the suction machine; a carbon dioxide recovery line connected to the discharge line; a recovery gas valve provided in the carbon dioxide recovery line; a non-recovery gas line connected to the discharge line; a non-recovery gas valve provided in the non-recovery gas line; and a control device that closes the recovery gas valve and opens the non-recovery gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum with respect to a predetermined recovery pressure, and closes the non-recovery gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum with respect to the recovery pressure. The control device includes a suction device controller that controls the operation of the suction device, and a valve controller that controls the opening and closing of the recovery gas valve and the non-recovered gas valve. The suction device controller operates the suction device to increase its suction force after a predetermined time has elapsed since the suction device created a vacuum inside the adsorption tower. The valve controller assumes that the pressure inside the adsorption tower is lower than the recovery pressure before the suction device controller increases the suction force of the suction device, and closes the recovery gas valve and opens the non-recovered gas valve after the suction device controller increases the suction force of the suction device, assuming that the pressure inside the adsorption tower is higher than the recovery pressure. A third embodiment of the invention for achieving the above objective is a carbon dioxide recovery system, A carbon dioxide recovery facility capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide comprises: an adsorption tower filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure; a blower that sends the exhaust gas into the adsorption tower; a suction machine that vacuums the inside of the adsorption tower; a discharge line connected to the discharge port of the suction machine; a carbon dioxide recovery line connected to the discharge line; a recovery gas valve provided in the carbon dioxide recovery line; a non-recovery gas line connected to the discharge line; a non-recovery gas valve provided in the non-recovery gas line; a control device that closes the recovery gas valve and opens the non-recovery gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum with respect to a predetermined recovery pressure, and closes the non-recovery gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum with respect to the recovery pressure; and a pretreatment device capable of removing moisture contained in the exhaust gas. The pretreatment device includes a dehumidifying tower capable of removing moisture contained in the exhaust gas from the blower, and a dry exhaust gas line that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower, to the adsorption tower. The non-recovered gas line has a recycling line connected to the dry exhaust gas line. The non-recovered gas valve has a recycling valve provided in the recycling line. The control device opens the recycling valve when the pressure in the adsorption tower is lower than the recovery pressure or is assumed to be lower than the recovery pressure, and closes the recycling valve when the pressure in the adsorption tower is higher than the recovery pressure or is assumed to be higher than the recovery pressure. A carbon dioxide recovery system as a fourth embodiment of the invention for achieving the above objective is: A carbon dioxide recovery facility capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide comprises: an adsorption tower filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure; a blower that sends the exhaust gas into the adsorption tower; a suction machine that vacuums the inside of the adsorption tower; a discharge line connected to the discharge port of the suction machine; a carbon dioxide recovery line connected to the discharge line; a recovery gas valve provided in the carbon dioxide recovery line; a non-recovery gas line connected to the discharge line; a non-recovery gas valve provided in the non-recovery gas line; a control device that closes the recovery gas valve and opens the non-recovery gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum with respect to a predetermined recovery pressure, and closes the non-recovery gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum with respect to the recovery pressure; and a pretreatment device capable of removing moisture contained in the exhaust gas. The pretreatment device includes a dehumidifying tower capable of removing moisture contained in the exhaust gas from the blower, and a dry exhaust gas line that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower, to the adsorption tower. The non-recovered gas line includes a non-recovered gas discharge line with an open end and a recycling line connected to the dry exhaust gas line. The non-recovered gas valve includes a discharge valve provided in the non-recovered gas discharge line and a recycling valve provided in the recycling line. The control device opens the discharge valve and closes the recycle valve when the pressure inside the adsorption tower is a vacuum lower than the recovery pressure and a vacuum lower than the recycling pressure which is closer to atmospheric pressure than the recovery pressure, or when it is assumed to be a vacuum lower than the recycling pressure. The control device closes the discharge valve and opens the recycle valve when the pressure inside the adsorption tower is a vacuum lower than the recovery pressure and a vacuum higher than the recycling pressure, or when it is assumed to be a vacuum lower than the recovery pressure and a vacuum higher than the recycling pressure. The control device closes the discharge valve and the recycle valve when the pressure inside the adsorption tower is a vacuum higher than the recovery pressure or when it is assumed to be a high vacuum.

[0009] The inventors vacuumed the inside of the adsorption tower and analyzed the gas components in the aspirated gas according to the pressure inside the tower at that time. Through this analysis, the inventors discovered the following phenomenon: When the vacuum level inside the adsorption tower is low, the nitrogen concentration in the aspirated gas is high and the carbon dioxide concentration in the aspirated gas is low. As the vacuum level inside the adsorption tower 41 is increased, the nitrogen concentration in the aspirated gas gradually decreases and the carbon dioxide concentration in the aspirated gas increases. This phenomenon is thought to be because the adsorption capacity of carbon dioxide to the carbon dioxide adsorbent is higher than the adsorption capacity of nitrogen to the carbon dioxide adsorbent.

[0010] Based on the above phenomena, the inventor conceived of the carbon dioxide recovery equipment in the first embodiment. In this embodiment, when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure, the aspirated gas is not recovered into a tank or the like. However, when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum relative to the recovery pressure, the aspirated gas is recovered into a tank or the like. Therefore, in this embodiment, high concentrations of carbon dioxide can be recovered.

[0011] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without providing a first-stage adsorption tower and a second-stage adsorption tower, as described above, thus reducing the number of components in the system. Therefore, in this embodiment, an increase in the installation area of ​​the system and an increase in equipment costs can be suppressed.

[0012] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without performing the adsorption process in two stages, thus shortening the time required to recover carbon dioxide from exhaust gas.

[0013] The invention relates to the purpose of achieving the aforementioned objective. First aspect As for carbon dioxide capture methods, In a carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, an adsorption tower filled with a carbon dioxide adsorbent formed of a carbon dioxide adsorbent capable of adsorbing carbon dioxide under high pressure and releasing carbon dioxide under low pressure is provided. An adsorption step of flowing the exhaust gas into the adsorption tower and adsorbing carbon dioxide in the exhaust gas by the carbon dioxide adsorbent, and a desorption step of evacuating the inside of the adsorption tower to desorb the carbon dioxide adsorbed by the carbon dioxide adsorbent from the carbon dioxide adsorbent are performed. The desorption step includes a carbon dioxide recovery step of guiding the gas from the adsorption tower as a recovered gas to a recovered gas tank, a non-recovered gas circulation step of guiding the gas from the adsorption tower as a non-recovered gas to a location excluding the recovered gas tank, and a control step of controlling the execution of the carbon dioxide recovery step and the non-recovered gas circulation step. In the control step, when the pressure inside the adsorption tower is in a high vacuum state or is assumed to be in a high vacuum state based on a predetermined recovery pressure, the carbon dioxide recovery step is executed, and when the pressure inside the adsorption tower is in a low vacuum state or is assumed to be in a low vacuum state based on the recovery pressure, the non-recovered gas circulation step is executed. The control process includes a pressure detection step for detecting the pressure inside the adsorption tower, a gas flow control step for executing one of the carbon dioxide recovery step and the non-recovered gas flow step based on the pressure detected in the pressure detection step, and a suction force control step for controlling the suction force for vacuum suction inside the adsorption tower. In the suction force control step, when the pressure detected in the pressure detection step becomes higher than the recovery pressure and closer to the recovery pressure than atmospheric pressure, or the suction force change pressure is the recovery pressure, the suction force is increased. As a second aspect of the invention for achieving the above objective, the carbon dioxide capture method is: A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide includes an adsorption step of introducing the exhaust gas into an adsorption tower, which is filled with a carbon dioxide adsorbent formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, thereby adsorbing the carbon dioxide in the exhaust gas onto the carbon dioxide adsorbent; and a detachment step of vacuuming the inside of the adsorption tower to detach the carbon dioxide adsorbed onto the carbon dioxide adsorbent. The detachment step includes a carbon dioxide recovery step of guiding the gas from the adsorption tower as a recovered gas to a recovered gas tank; a non-recovered gas flow step of guiding the gas from the adsorption tower as a non-recovered gas to a location other than the recovered gas tank; and a control step of controlling the execution of the carbon dioxide recovery step and the non-recovered gas flow step. In the control step, the carbon dioxide recovery step is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum based on a predetermined recovery pressure, and the non-recovered gas flow step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum based on the recovery pressure. The control process includes a suction force control process for controlling the suction force used to create a vacuum inside the adsorption tower, and a gas flow control process for executing one of the carbon dioxide recovery process and the non-recovered gas flow process. In the suction force control process, the suction force is increased after a predetermined time has elapsed since the start of vacuum suction inside the adsorption tower. In the gas flow control process, the non-recovered gas flow process is executed assuming that the pressure inside the adsorption tower is lower than the recovery pressure before the suction force is increased in the suction force control process, and the carbon dioxide recovery process is executed assuming that the pressure inside the adsorption tower is higher than the recovery pressure after the suction force is increased in the suction force control process. A third aspect of the invention for achieving the aforementioned objective is a carbon dioxide recovery method, A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide includes an adsorption step of introducing the exhaust gas into an adsorption tower, which is filled with a carbon dioxide adsorbent formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and adsorbing the carbon dioxide in the exhaust gas onto the carbon dioxide adsorbent; a detachment step of detaching the carbon dioxide adsorbed on the carbon dioxide adsorbent by vacuum suction inside the adsorption tower; and a pretreatment step of removing moisture contained in the exhaust gas. The detachment step includes a carbon dioxide recovery step of guiding the gas from the adsorption tower as recovered gas to a recovered gas tank; a non-recovered gas flow step of guiding the gas from the adsorption tower as non-recovered gas to a location other than the recovered gas tank; and a control step of controlling the execution of the carbon dioxide recovery step and the non-recovered gas flow step. The pretreatment includes a dehumidification step of sending the exhaust gas into a dehumidification tower to remove moisture from the exhaust gas and guiding the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower, to the adsorption tower. The non-recovered gas flow process includes a recycling process in which the non-recovered gas is mixed into the dry exhaust gas. The control process executes the carbon dioxide recovery process when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure; executes the non-recovered gas flow process when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure; executes the recycling process when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure; and does not execute the recycling process when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to the recovery pressure. A fourth aspect of the invention for achieving the aforementioned objective is a carbon dioxide capture method, A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide includes an adsorption step of introducing the exhaust gas into an adsorption tower, which is filled with a carbon dioxide adsorbent formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and adsorbing the carbon dioxide in the exhaust gas onto the carbon dioxide adsorbent; a detachment step of detaching the carbon dioxide adsorbed on the carbon dioxide adsorbent by vacuum suction inside the adsorption tower; and a pretreatment step of removing moisture contained in the exhaust gas. The detachment step includes a carbon dioxide recovery step of guiding the gas from the adsorption tower as recovered gas to a recovered gas tank; a non-recovered gas flow step of guiding the gas from the adsorption tower as non-recovered gas to a location other than the recovered gas tank; and a control step of controlling the execution of the carbon dioxide recovery step and the non-recovered gas flow step. The pretreatment includes a dehumidification step of sending the exhaust gas into a dehumidification tower to remove moisture from the exhaust gas and guiding the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower, to the adsorption tower. The non-recovered gas distribution process includes a non-recovered gas release process for releasing the non-recovered gas into the atmosphere, and a recycling process for mixing the non-recovered gas into the dry exhaust gas. In the control step, the carbon dioxide recovery step is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure; the unrecovered gas flow step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure; the unrecovered gas discharge step is executed and the recycling step is not executed when the pressure inside the adsorption tower is a lower vacuum than the recovery pressure and is closer to atmospheric pressure than the recovery pressure and is a lower vacuum than the recycling pressure, or is assumed to be a lower vacuum than the recycling pressure; the unrecovered gas discharge step is not executed and the recycling step is executed when the pressure inside the adsorption tower is a lower vacuum than the recovery pressure and is a higher vacuum than the recycling pressure, or is assumed to be a lower vacuum than the recovery pressure and is a higher vacuum than the recycling pressure; and the unrecovered gas discharge step and the recycling step are not executed when the pressure inside the adsorption tower is a higher vacuum or is assumed to be a high vacuum than the recovery pressure.

[0014] In this aspect, the same effects as those of the carbon dioxide recovery equipment in the above aspect can be obtained. That is, in this aspect as well, without providing the first-stage adsorption tower and the second-stage adsorption tower as in the equipment described in Non-Patent Document 1, high-concentration carbon dioxide can be recovered. Also, in this aspect, the time for recovering carbon dioxide from the exhaust gas can be shortened.

Effects of the Invention

[0015] According to one aspect of the present disclosure, it is possible to suppress an increase in the installation area of equipment and an increase in equipment costs while recovering high-concentration carbon dioxide from exhaust gas.

Brief Description of the Drawings

[0016] [Figure 1] It is a system diagram (Part 1) of the carbon dioxide recovery equipment in the first embodiment according to the present disclosure. [Figure 2] It is a system diagram (Part 2) of the carbon dioxide recovery equipment in the first embodiment according to the present disclosure. [Figure 3] It is a perspective view of the main part of the carbon dioxide adsorbent in one embodiment according to the present disclosure. [Figure 4] It is a flowchart showing the operation of the carbon dioxide recovery equipment in the first embodiment according to the present disclosure. [Figure 5] It is an explanatory diagram showing the analysis results when using NaX-type zeolite. [Figure 6] It is an explanatory diagram showing the analysis results when using LiX-type zeolite. [Figure 7] It is an explanatory diagram showing the analysis results when using CaX-type zeolite. [Figure 8] It is a graph showing the change in gauge pressure in the adsorption tower over time in the first embodiment according to the present disclosure. [Figure 9] It is a system diagram of the carbon dioxide recovery equipment in the second embodiment according to the present disclosure. [Figure 10] It is a flowchart showing the operation of the carbon dioxide recovery equipment in the second embodiment according to the present disclosure. <​​​​​​​​​​This is a diagram of the carbon dioxide capture equipment in the fourth embodiment relating to this disclosure. [Figure 15] This is an explanatory diagram showing the configuration of a suction device in one embodiment of the fourth embodiment relating to this disclosure. [Figure 16] This is an explanatory diagram showing the configuration of a suction device in another embodiment of the fourth embodiment relating to this disclosure. [Figure 17] This is a flowchart showing the operation of the carbon dioxide capture equipment in the fourth embodiment of the present disclosure. [Figure 18] This graph shows the change in gauge pressure in the adsorption tower over time in the fourth embodiment of the present disclosure. [Figure 19] This is a diagram of the carbon dioxide recovery equipment in the fifth embodiment relating to this disclosure. [Figure 20] This is a flowchart showing the operation of the carbon dioxide capture equipment in the fifth embodiment of the present disclosure. [Figure 21] This graph shows the change in gauge pressure in the adsorption tower over time in the fifth embodiment of the present disclosure. [Modes for carrying out the invention]

[0017] Various embodiments and modifications of the carbon dioxide capture equipment relating to this disclosure will be described below with reference to the drawings.

[0018] "First Embodiment" A first embodiment of the carbon dioxide capture system will be described with reference to Figures 1 to 8.

[0019] The carbon dioxide recovery equipment in this embodiment, as shown in Figure 1, is equipment that recovers carbon dioxide from exhaust gas from an exhaust gas source 1. Examples of exhaust gas sources 1 include incinerators, boilers, and gas turbines. The composition of the exhaust gas from the exhaust gas source 1 is, for example, as follows: N2:75.9vol%, O2:9.6vol%, CO2:5.4vol%, H2O:9.2vol%

[0020] This carbon dioxide recovery system comprises a pretreatment device 10 and a carbon dioxide recovery device 40. The pretreatment device 10 is a device that removes components from the exhaust gas that would hinder carbon dioxide recovery by the carbon dioxide recovery device 40. The carbon dioxide recovery device 40 is a device that primarily recovers carbon dioxide from the exhaust gas from the pretreatment device 10.

[0021] The pretreatment device 10 comprises two dehumidifying towers 11. Each of the two dehumidifying towers 11 has a container 12 and a moisture adsorbent 15 filled inside the container 12. The moisture adsorbent 15 is made of a moisture adsorbent capable of adsorbing moisture. Examples of moisture adsorbents include activated alumina, silica gel, and zeolite. Each of the two dehumidifying towers 11 has a first opening 13 and a second opening 14 in its container 12. The first opening 13 is formed on one side of the container 12 relative to the moisture adsorbent 15, and the second opening 14 is formed on the other side of the container 12 relative to the moisture adsorbent 15. In the following description, one of the two dehumidifying towers 11 will be referred to as the first dehumidifying tower 11a, and the remaining dehumidifying tower 11 as the second dehumidifying tower 11b.

[0022] The carbon dioxide recovery device 40 comprises three adsorption towers 41. Each of the three adsorption towers 41 has a container 42 and carbon dioxide adsorbent 45 filled inside the container 42. The carbon dioxide adsorbent 45 is made of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure. In this embodiment, the carbon dioxide adsorbent is zeolite. Each of the three adsorption towers 41 has a first opening 43 and a second opening 44 in the container 42. The first opening 43 is formed on one side of the container 42 with respect to the carbon dioxide adsorbent 45, and the second opening 44 is formed on the other side of the container 42 with respect to the carbon dioxide adsorbent 45. In the following description, one of the three adsorption towers 41 will be referred to as the first adsorption tower 41a, another as the second adsorption tower 41b, and the remaining adsorption tower 41 as the third adsorption tower 41c. As shown in Figure 3, the carbon dioxide adsorbent 45 is a porous structure in which multiple through-holes 46 are formed, each penetrating in the same direction. The porous structure shown in Figure 3 is sometimes referred to as a honeycomb structure.

[0023] Zeolite, a type of carbon dioxide adsorbent, can adsorb not only carbon dioxide but also water. Therefore, if water is present in the exhaust gas, the carbon dioxide adsorption capacity of the zeolite decreases. In this embodiment, the pretreatment device 10 removes water from the exhaust gas.

[0024] In addition to the aforementioned first dehumidification tower 11a and second dehumidification tower 11b, the pretreatment device 10 includes a blower 16, a dehumidification vacuum pump 17, an exhaust gas line 20, a dry exhaust gas line 23, a moisture-rich gas line 27, an off-gas line 30, a first exhaust gas valve 35a, a second exhaust gas valve 35b, a first dry exhaust gas valve 36a on the dehumidification side, a second dry exhaust gas valve 36b on the dehumidification side, a first moisture-rich gas valve 37a, a second moisture-rich gas valve 37b, a first off-gas valve 38a on the dehumidification side, and a second off-gas valve 38b on the dehumidification side.

[0025] The exhaust gas line 20 includes a main exhaust gas line 21, a first exhaust gas line 22a, and a second exhaust gas line 22b. One end of the main exhaust gas line 21 is connected to the exhaust gas source 1. The other end of the main exhaust gas line 21 is connected to one end of the first exhaust gas line 22a and one end of the second exhaust gas line 22b. Therefore, the first exhaust gas line 22a and the second exhaust gas line 22b are lines branched from the main exhaust gas line 21. A blower 16 is provided on the main exhaust gas line 21. The other end of the first exhaust gas line 22a is connected to the first port 13 of the first dehumidification tower 11a, and the other end of the second exhaust gas line 22b is connected to the first port 13 of the second dehumidification tower 11b. A first exhaust gas valve 35a is provided on the first exhaust gas line 22a. A second exhaust gas valve 35b is provided on the second exhaust gas line 22b.

[0026] The drying exhaust gas line 23 includes a dehumidification-side first drying exhaust gas line 24a, a dehumidification-side second drying exhaust gas line 24b, a main drying exhaust gas line 25, a recovery-side first drying exhaust gas line 26a, a recovery-side second drying exhaust gas line 26b, and a recovery-side third drying exhaust gas line 26c. One end of the dehumidification-side first drying exhaust gas line 24a is connected to the second port 14 of the first dehumidification tower 11a, and one end of the dehumidification-side second drying exhaust gas line 24b is connected to the second port 14 of the second dehumidification tower 11b. The dehumidification-side first drying exhaust gas line 24a is provided with a dehumidification-side first drying exhaust gas valve 36a. The dehumidification-side second drying exhaust gas line 24b is provided with a dehumidification-side second drying exhaust gas valve 36b. One end of the main drying exhaust gas line 25 is connected to the other end of the dehumidification-side first drying exhaust gas line 24a and the other end of the dehumidification-side second drying exhaust gas line 24b. The other end of the main dry exhaust gas line 25 is connected to one end of the recovery side first dry exhaust gas line 26a, one end of the recovery side second dry exhaust gas line 26b, and one end of the recovery side third dry exhaust gas line 26c. Therefore, the recovery side first dry exhaust gas line 26a, the recovery side second dry exhaust gas line 26b, and the recovery side third dry exhaust gas line 26c are lines branched from the main dry exhaust gas line 25. The other end of the recovery side first dry exhaust gas line 26a is connected to the first port 43 of the first adsorption tower 41a. The other end of the recovery side second dry exhaust gas line 26b is connected to the first port 43 of the second adsorption tower 41b. The other end of the recovery side third dry exhaust gas line 26c is connected to the first port 43 of the third adsorption tower 41c.

[0027] The moisture-rich gas line 27 comprises a first moisture-rich gas line 28a, a second moisture-rich gas line 28b, and a main moisture-rich gas line 29. One end of the first moisture-rich gas line 28a is connected in the first exhaust gas line 22a to a position closer to the first dehumidification tower 11a than the first exhaust gas valve 35a. One end of the second moisture-rich gas line 28b is connected in the second exhaust gas line 22b to a position closer to the second dehumidification tower 11b than the second exhaust gas valve 35b. The first moisture-rich gas line 28a is provided with a first moisture-rich gas valve 37a, and the second moisture-rich gas line 28b is provided with a second moisture-rich gas valve 37b. One end of the main moisture-rich gas line 29 is connected to the other end of the first moisture-rich gas line 28a and the other end of the second moisture-rich gas line 28b. The other end of the main moisture-rich gas line 29 is connected to the suction port of the dehumidification vacuum pump 17.

[0028] The off-gas line 30 includes a recovery-side first off-gas line 31a, a recovery-side second off-gas line 31b, a recovery-side third off-gas line 31c, a main off-gas line 32, a dehumidification-side first off-gas line 33a, and a dehumidification-side second off-gas line 33b. One end of the recovery-side first off-gas line 31a is connected to the second port 44 of the first adsorption tower 41a. One end of the recovery-side second off-gas line 31b is connected to the second port 44 of the second adsorption tower 41b. One end of the recovery-side third off-gas line 31c is connected to the second port 44 of the third adsorption tower 41c. The other end of the recovery-side first off-gas line 31a, the other end of the recovery-side second off-gas line 31b, and the other end of the recovery-side third off-gas line 31c are connected to one end of the main off-gas line 32. The other end of the main off-gas line 32 is connected to one end of the dehumidifying side first off-gas line 33a and one end of the dehumidifying side second off-gas line 33b. The other end of the dehumidifying side first off-gas line 33a is connected to the second port 14 of the first dehumidifying tower 11a. The other end of the dehumidifying side second off-gas line 33b is connected to the second port 14 of the second dehumidifying tower 11b. The dehumidifying side first off-gas line 33a is provided with a dehumidifying side first off-gas valve 38a. The dehumidifying side second off-gas line 33b is provided with a dehumidifying side second off-gas valve 38b.

[0029] The carbon dioxide recovery device 40 includes, in addition to the aforementioned first adsorption tower 41a, second adsorption tower 41b, and third adsorption tower 41c, a blower 16, a dry exhaust gas line 23, a suction device 50, a recovery-side first dry exhaust gas valve 56a, a recovery-side second dry exhaust gas valve 56b, a recovery-side third dry exhaust gas valve 56c, a first suction valve 57a, a second suction valve 57b, a third suction valve 57c, a recovery-side first off-gas valve 58a, a recovery-side second off-gas valve 58b, a recovery-side third off-gas valve 58c, a recovery gas valve 60, a non-recovery gas valve 61, a recovery gas tank 63, a suction line 65, an off-gas line 30, a discharge line 68, a carbon dioxide recovery line 70, a non-recovery gas line 71, and a control device 80.

[0030] Among the components of the carbon dioxide recovery device 40, the blower 16, the dry exhaust gas line 23, and the off-gas line 30 are components of the carbon dioxide recovery device 40, as well as components of the pretreatment device 10.

[0031] The first dry exhaust gas valve 56a on the recovery side is provided in the first dry exhaust gas line 26a on the recovery side. The second dry exhaust gas valve 56b on the recovery side is provided in the second dry exhaust gas line 26b on the recovery side. The third dry exhaust gas valve 56c on the recovery side is provided in the third dry exhaust gas line 26c on the recovery side. The first off-gas valve 58a on the recovery side is provided in the first off-gas line 31a on the recovery side. The second off-gas valve 58b on the recovery side is provided in the second off-gas line 31b on the recovery side. The third off-gas valve 58c on the recovery side is provided in the third off-gas line 31c on the recovery side.

[0032] The suction line 65 includes a first suction line 66a, a second suction line 66b, a third suction line 66c, and a main suction line 67. One end of the first suction line 66a is connected in the recovery-side first dry exhaust gas line 26a to a position closer to the first adsorption tower 41a than the recovery-side first dry exhaust gas valve 56a. The first suction line 66a is provided with a first suction valve 57a. One end of the second suction line 66b is connected in the recovery-side second dry exhaust gas line 26b to a position closer to the second adsorption tower 41b than the recovery-side second dry exhaust gas valve 56b. The second suction line 66b is provided with a second suction valve 57b. One end of the third suction line 66c is connected in the recovery-side third dry exhaust gas line 26c to a position closer to the third adsorption tower 41c than the recovery-side third dry exhaust gas valve 56c. The third suction line 66c is provided with a third suction valve 57c. The other end of the first suction line 66a, the other end of the second suction line 66b, and the other end of the third suction line 66c are connected to one end of the main suction line 67. The other end of the main suction line 67 is connected to the suction port of the suction machine 50.

[0033] The suction device 50 is, for example, a vacuum pump.

[0034] One end of the discharge line 68 is connected to the discharge port of the suction device 50. The other end of the discharge line 68 is connected to one end of the carbon dioxide recovery line 70 and one end of the non-recovered gas line 71. The non-recovered gas line 71 has a non-recovered gas discharge line 72a with an open end. The non-recovered gas valve 61 has a discharge valve 62a provided in the non-recovered gas discharge line 72a. The other end of the carbon dioxide recovery line 70 is connected to the recovery gas tank 63. The carbon dioxide recovery line 70 is provided with a recovery gas valve 60.

[0035] The control device 80 includes a pressure gauge 81 provided for each of the three adsorption towers 41, and a valve controller 82 that controls the operation of the recovery gas valve 60 and the discharge valve 62a based on the pressure detected by the pressure gauge 81.

[0036] Next, the operation of the carbon dioxide capture equipment described above will be explained according to the flowchart shown in Figure 4.

[0037] The carbon dioxide recovery equipment performs a pretreatment S10 and a carbon dioxide recovery treatment S20. The pretreatment S10 is performed by the pretreatment device 10, and the carbon dioxide recovery treatment S20 is performed by the carbon dioxide recovery device 40.

[0038] In the pre-treatment S10, the dehumidification process S11 and the regeneration process S12 are performed. Let's assume that the amount of moisture adsorbed by the moisture adsorbent 15 in the first dehumidification tower 11a is very small, and the amount of moisture adsorbed by the moisture adsorbent 15 in the second dehumidification tower 11b is large. In this case, as shown in Figure 1, the first exhaust gas valve 35a is open, the second exhaust gas valve 35b is closed, the first drying exhaust gas valve 36a on the dehumidification side is open, the second drying exhaust gas valve 36b on the dehumidification side is closed, the first moisture-rich gas valve 37a is closed, the second moisture-rich gas valve 37b is open, the first off-gas valve 38a on the dehumidification side is closed, and the second off-gas valve 38b on the dehumidification side is open.

[0039] In this case, exhaust gas from exhaust gas source 1 flows into the first dehumidification tower 11a via the main exhaust gas line 21, blower 16, first exhaust gas line 22a, and first exhaust gas valve 35a. As the exhaust gas flows into the first dehumidification tower 11a, it passes through the moisture adsorbent 15 inside the first dehumidification tower 11a, and most of the moisture contained in the exhaust gas is adsorbed by the moisture adsorbent 15. The remainder is then exhausted from the first dehumidification tower 11a as dry exhaust gas. In other words, dehumidification of the exhaust gas is performed in the first dehumidification tower 11a. This dry exhaust gas is sent to the carbon dioxide recovery device 40 via the dehumidification side first dry exhaust gas line 24a, the dehumidification side first dry exhaust gas valve 36a, and the main dry exhaust gas line 25 (dehumidification process S11).

[0040] Furthermore, in this case, off-gas with low moisture content flows from the carbon dioxide recovery device 40 into the second dehumidification tower 11b via the main off-gas line 32, the dehumidification-side second off-gas line 33b, and the dehumidification-side second off-gas valve 38b. The off-gas that flows into the second dehumidification tower 11b passes through the moisture adsorbent 15 inside the second dehumidification tower 11b, releasing moisture from the adsorbent 15, and is exhausted from the second dehumidification tower 11b along with the moisture. In other words, the moisture adsorbent 15 is regenerated in the second dehumidification tower 11b. The off-gas containing moisture is released to the outside as moisture-rich gas via the second moisture-rich gas line 28b, the second moisture-rich gas valve 37b, the main moisture-rich gas line 29, and the dehumidification vacuum pump 17 (regeneration process S12). The destination for the moisture-rich gas may be the atmosphere or a tank.

[0041] As described above, when the dehumidification process S11 is performed in the first dehumidification tower 11a, the amount of moisture adsorbed by the moisture adsorbent 15 in the first dehumidification tower 11a increases. Also, when the regeneration process S12 is performed in the second dehumidification tower 11b, the amount of moisture adsorbed by the moisture adsorbent 15 in the second dehumidification tower 11b decreases significantly.

[0042] Furthermore, suppose that the amount of moisture adsorbed by the moisture adsorbent 15 in the first dehumidification tower 11a is large, and the amount of moisture adsorbed by the moisture adsorbent 15 in the second dehumidification tower 11b is extremely small. In this case, as shown in Figure 2, the first exhaust gas valve 35a is closed, the second exhaust gas valve 35b is open, the first drying exhaust gas valve 36a on the dehumidification side is closed, the second drying exhaust gas valve 36b on the dehumidification side is open, the first moisture-rich gas valve 37a is open, the second moisture-rich gas valve 37b is closed, the first off-gas valve 38a on the dehumidification side is open, and the second off-gas valve 38b on the dehumidification side is closed.

[0043] In this case, exhaust gas from exhaust gas source 1 flows into the second dehumidification tower 11b via the main exhaust gas line 21, blower 16, second exhaust gas line 22b, and second exhaust gas valve 35b. As the exhaust gas flows into the second dehumidification tower 11b, it passes through the moisture adsorbent 15 inside the second dehumidification tower 11b, and most of the moisture contained in the exhaust gas is adsorbed by the moisture adsorbent 15. The remainder is then exhausted from the second dehumidification tower 11b as dry exhaust gas. In other words, dehumidification of the exhaust gas is performed in the second dehumidification tower 11b. This dry exhaust gas is sent to the carbon dioxide recovery device 40 via the dehumidification-side second dry exhaust gas line 24b, the dehumidification-side second dry exhaust gas valve 36b, and the main dry exhaust gas line 25 (dehumidification process S11).

[0044] Furthermore, in this case, off-gas with low moisture content flows from the carbon dioxide recovery device 40 into the first dehumidification tower 11a via the main off-gas line 32, the dehumidification-side first off-gas line 33a, and the dehumidification-side first off-gas valve 38a. The off-gas that flows into the first dehumidification tower 11a passes through the moisture adsorbent 15 inside the first dehumidification tower 11a, releasing moisture from the moisture adsorbent 15, and is exhausted from the first dehumidification tower 11a along with the moisture. In other words, the moisture adsorbent 15 is regenerated in the first dehumidification tower 11a. The off-gas containing moisture is released to the outside as moisture-rich gas via the first moisture-rich gas line 28a, the first moisture-rich gas valve 37a, the main moisture-rich gas line 29, and the dehumidification vacuum pump 17 (regeneration process S12).

[0045] As described above, in the first dehumidification tower 11a and the second dehumidification tower 11b of the pretreatment device 10, the regeneration process S12 is executed after the dehumidification process S11, and the dehumidification process S11 is executed after the regeneration process S12. Furthermore, if the dehumidification process S11 is being executed in the first dehumidification tower 11a, the regeneration process S12 is executed in the second dehumidification tower 11b. Also, if the dehumidification process S11 is being executed in the second dehumidification tower 11b, the regeneration process S12 is executed in the first dehumidification tower 11a. For this reason, in this embodiment, moisture in the exhaust gas can be continuously removed.

[0046] In the carbon dioxide recovery process S20, the adsorption process S21, the detachment process S22, and the pressurization process S32 are executed. Assume that the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the first adsorption tower 41a and the carbon dioxide adsorbent 45 in the second adsorption tower 41b is extremely small, and the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the third adsorption tower 41c is large. Furthermore, assume that there is negative pressure inside the first adsorption tower 41a and approximately atmospheric pressure inside the second adsorption tower 41b. In this case, as shown in Figure 1, the recovery side first dry exhaust gas valve 56a is closed, the recovery side second dry exhaust gas valve 56b is open, the recovery side third dry exhaust gas valve 56c is closed, the first suction valve 57a is closed, the second suction valve 57b is closed, the third suction valve 57c is open, the recovery side first off-gas valve 58a is half-open, the recovery side second off-gas valve 58b is open, and the recovery side third off-gas valve 58c is closed.

[0047] In this case, the dry exhaust gas from the pretreatment device 10 flows into the second adsorption tower 41b via the main dry exhaust gas line 25, the recovery-side second dry exhaust gas line 26b, and the recovery-side second dry exhaust gas valve 56b. As the dry exhaust gas flows into the second adsorption tower 41b, it passes through the carbon dioxide adsorbent 45 in the second adsorption tower 41b, most of the carbon dioxide contained in the dry exhaust gas is adsorbed by the carbon dioxide adsorbent 45, and the remainder is exhausted from the second adsorption tower 41b as off-gas. In other words, the carbon dioxide adsorbent 45 in the second adsorption tower 41b adsorbs carbon dioxide in the dry exhaust gas (adsorption process S21). As mentioned above, the carbon dioxide adsorbent 45 is a porous structure. Therefore, it does not become fluid due to the gas flow in the second adsorption tower 41b, and the outflow of the carbon dioxide adsorbent 45 from the adsorption tower 41 can be avoided. A portion of the off-gas exhausted from the second adsorption tower 41b is sent to the dehumidification tower 11 during the regeneration process S12 via the recovery-side second off-gas line 31b, the recovery-side second off-gas valve 58b, and the main off-gas line 32.

[0048] Furthermore, a portion of the remaining off-gas exhausted from the second adsorption tower 41b is sent into the first adsorption tower 41a via the recovery-side second off-gas line 31b, the recovery-side second off-gas valve 58b, the main off-gas line 32, the recovery-side first off-gas line 31a, and the recovery-side first off-gas valve 58a. As a result, the pressure inside the first adsorption tower 41a is increased from negative pressure to approximately atmospheric pressure (pressure boosting process S32).

[0049] Furthermore, in this case, the inside of the third adsorption tower 41c is vacuum-suctioned by the suction machine 50 via the third suction line 66c, the third suction valve 57c, and the main suction line 67. As a result, the carbon dioxide adsorbed on the carbon dioxide adsorbent 45 inside the third adsorption tower 41c is released and discharged from the suction machine 50 (release step S22). The release step S22 will be explained in detail later.

[0050] As described above, when the adsorption process S21 is performed in the second adsorption tower 41b, the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the second adsorption tower 41b increases. Also, when the detachment process S22 is performed in the third adsorption tower 41c, the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the third adsorption tower 41c decreases to a very small amount, and the inside of the third adsorption tower 41c becomes negative pressure. Furthermore, when the pressurization process S32 is performed in the first adsorption tower 41a, the inside of the first adsorption tower 41a becomes approximately atmospheric pressure. At this time, the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the first adsorption tower 41a is extremely small.

[0051] Furthermore, let's assume that the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the first adsorption tower 41a and the carbon dioxide adsorbent 45 in the third adsorption tower 41c is extremely small, and the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the second adsorption tower 41b is large. In addition, let's assume that the pressure inside the first adsorption tower 41a is approximately atmospheric pressure, and the pressure inside the third adsorption tower 41c is negative. In this case, as shown in Figure 2, the recovery side first dry exhaust gas valve 56a is open, the recovery side second dry exhaust gas valve 56b is closed, the recovery side third dry exhaust gas valve 56c is closed, the first suction valve 57a is closed, the second suction valve 57b is open, the third suction valve 57c is closed, the recovery side first off-gas valve 58a is open, the recovery side second off-gas valve 58b is closed, and the recovery side third off-gas valve 58c is half-open.

[0052] In this case, the dry exhaust gas from the pretreatment device 10 flows into the first adsorption tower 41a via the main dry exhaust gas line 25, the recovery side first dry exhaust gas line 26a, and the recovery side first dry exhaust gas valve 56a. As the dry exhaust gas flows into the first adsorption tower 41a, it passes through the carbon dioxide adsorbent 45 in the first adsorption tower 41a, most of the carbon dioxide contained in the dry exhaust gas is adsorbed by the carbon dioxide adsorbent 45, and the remainder is exhausted from the first adsorption tower 41a as off-gas. That is, the first adsorption tower 41a adsorbs carbon dioxide in the dry exhaust gas (adsorption process S21). A portion of the off-gas exhausted from the first adsorption tower 41a is sent to the dehumidification tower 11 in the regeneration process S12 via the recovery side first off-gas line 31a, the recovery side first off-gas valve 58a, and the main off-gas line 32.

[0053] Furthermore, a portion of the remaining off-gas exhausted from the first adsorption tower 41a is sent into the third adsorption tower 41c via the recovery-side first off-gas line 31a, the recovery-side first off-gas valve 58a, the main off-gas line 32, the recovery-side third off-gas line 31c, and the recovery-side third off-gas valve 58c. As a result, the pressure inside the third adsorption tower 41c is increased from negative pressure to approximately atmospheric pressure (pressure boosting process S32).

[0054] Furthermore, in this case, the inside of the second adsorption tower 41b is vacuum-suctioned by the suction machine 50 via the second suction line 66b, the second suction valve 57b, and the main suction line 67. As a result, the carbon dioxide adsorbed on the carbon dioxide adsorbent 45 inside the second adsorption tower 41b is released and discharged from the suction machine 50 (release process S22).

[0055] As described above, in the first adsorption tower 41a, the second adsorption tower 41b, and the third adsorption tower 41c of the carbon dioxide recovery device 40, a detachment process S22 is performed after the adsorption process S21, a pressurization process S32 is performed after the detachment process S22, and an adsorption process S21 is performed after the pressurization process S32. Furthermore, when the adsorption process S21 is being performed in the second adsorption tower 41b, a detachment process S22 is performed in the third adsorption tower 41c, and a pressurization process S32 is performed in the first adsorption tower 41a. Also, when the amount of carbon dioxide adsorbed by the carbon dioxide adsorbent 45 in the second adsorption tower 41b increases, a detachment process S22 is performed in the second adsorption tower 41b, a pressurization process S32 is performed in the third adsorption tower 41c, and an adsorption process S21 is performed in the first adsorption tower 41a. For this reason, in this embodiment, carbon dioxide in the dry exhaust gas can be continuously recovered.

[0056] In this embodiment, as described above, the pressurization step S32 is performed after the detachment step S22. The vacuum level inside the adsorption tower 41 is high after the detachment step S22. Therefore, if the adsorption step S21 is performed while the vacuum level is still high, even if exhaust gas is sent into the adsorption tower 41, the exhaust gas will blow through the carbon dioxide adsorbed material 45, reducing the carbon dioxide adsorption efficiency. For this reason, in this embodiment, the pressurization step S32 is performed after the detachment step S22, and then the adsorption step S21 is performed.

[0057] By the way, the zeolite used as a carbon dioxide adsorbent in this embodiment is a general term for crystalline aluminosilicates. The chemical formula of this zeolite can be expressed as follows. Me2 / xO·Al2O3·mSiO2·nH2O Me: X-valent cation

[0058] Zeolite crystal structures are not uniform; for example, there are A-type, X-type, Y-type, and Beta-type zeolites. Furthermore, the Me ion in the above chemical formulas can be Na ions, Li ions, Ca ions, etc. Therefore, various types of zeolites exist depending on their crystal structure and the cations they contain. For example, a zeolite with an X-type crystal structure and using Na ions as Me is represented as the NaX type. Similarly, a zeolite with an X-type crystal structure and using Li ions as Me is represented as the LiX type, and a zeolite with an X-type crystal structure and using Ca ions as Me is represented as the CaX type.

[0059] The inventors vacuum-suctioned the inside of the adsorption tower 41 and analyzed the gas components in the aspirated gas according to the gauge pressure inside the adsorption tower 41 at that time. The results of this gas analysis are shown in Figures 5 to 7. Figure 5 shows the analysis results when using NaX type zeolite. Figure 6 shows the analysis results when using LiaX type zeolite. Figure 7 shows the analysis results when using CaX type zeolite.

[0060] As shown in Figures 5 to 7, with any type of zeolite, when the vacuum level in the adsorption tower 41 is low, in other words, when the gauge pressure in the adsorption tower 41 is high, the nitrogen concentration in the aspirated gas is high and the carbon dioxide concentration in the aspirated gas is low. When the vacuum level in the adsorption tower 41 is increased, in other words, when the gauge pressure in the adsorption tower 41 is decreased, the nitrogen concentration in the aspirated gas gradually decreases and the carbon dioxide concentration in the aspirated gas increases. For example, when the gauge pressure in the adsorption tower 41 is -80kPa, the carbon dioxide concentration in the aspirated gas is approximately 80% regardless of the type of zeolite.

[0061] Based on the above analysis results, the inventors have made it possible to recover high concentrations of carbon dioxide by not recovering the aspirated gas into a tank or the like when the pressure inside the adsorption tower 41 is low vacuum relative to a predetermined recovery pressure Pc, and by recovering the aspirated gas into a tank or the like when the pressure inside the adsorption tower 41 is high vacuum relative to the recovery pressure Pc. In this embodiment and the following embodiments, the recovery pressure Pc is set to -80 kPaG.

[0062] As shown in Figure 4, the aforementioned detachment process S22 includes a control process S23, a non-recovered gas flow process S27, and a carbon dioxide recovery process S31. The control process S23 includes a pressure detection process S24 in which a pressure gauge 81 detects the pressure inside the adsorption tower 41 during the detachment process S22, and a gas flow control process S26 in which a valve controller 82 controls the opening and closing of the recovery gas valve 60 and the release valve 62a based on the pressure detected by the pressure gauge 81. The non-recovered gas flow process S27 also includes a non-recovered gas release process S28 in which the gas drawn in from the suction device 50 is released into the atmosphere.

[0063] When the inside of the adsorption tower 41, which is the target of the detachment process S22, is vacuum-suctioned by the suction device 50, as shown in Figure 8, the gauge pressure inside the adsorption tower 41 gradually decreases over time, or in other words, the vacuum level inside the adsorption tower 41 gradually increases. The valve controller 82 gives a closing instruction to the recovery gas valve 60 and an opening instruction to the discharge valve 62a when the pressure inside the adsorption tower 41 detected by the pressure gauge 81 is low vacuum relative to the recovery pressure Pc (gas flow control process S26). As a result, the recovery gas valve 60 becomes closed and the discharge valve 62a becomes open, and the gas sucked from the suction device 50 is released into the atmosphere via the non-recovered gas discharge line 72a and the discharge valve 62a (non-recovered gas discharge process S28).

[0064] As the gauge pressure inside the adsorption tower 41 gradually decreases, and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a high vacuum relative to the recovery pressure Pc, the valve controller 82 gives an open command to the recovery gas valve 60 and a close command to the discharge valve 62a (gas flow control process S26). As a result, the recovery gas valve 60 becomes open and the discharge valve 62a becomes closed, and the gas drawn from the suction device 50 is recovered into the recovery gas tank 63 via the carbon dioxide recovery line 70 and the recovery gas valve 60 (carbon dioxide recovery process S31).

[0065] As described above, in this embodiment, when the pressure inside the adsorption tower 41 becomes a high vacuum relative to the recovery pressure Pc, the aspirated gas from the suction device 50 is guided to the recovery gas tank 63. As previously stated, when the vacuum level inside the adsorption tower 41 is higher than the recovery pressure Pc (-80kPaG), the concentration of carbon dioxide in the aspirated gas becomes approximately 80% or higher. Therefore, in this embodiment, high concentrations of carbon dioxide can be recovered.

[0066] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without providing a first-stage adsorption tower and a second-stage adsorption tower, as described above, thus reducing the number of components in the system. Therefore, in this embodiment, an increase in the installation area and equipment costs can be suppressed.

[0067] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without performing the adsorption process S21 in two stages, thus shortening the time required to recover carbon dioxide from exhaust gas.

[0068] "Second Embodiment" A second embodiment of the carbon dioxide capture system will be described with reference to Figures 9 and 10.

[0069] As shown in Figure 9, the carbon dioxide recovery equipment in this embodiment includes a pretreatment device 10 and a carbon dioxide recovery device 40a, similar to the carbon dioxide recovery equipment in the first embodiment. The pretreatment device 10 in this embodiment is the same as the pretreatment device 10 in the first embodiment. On the other hand, the carbon dioxide recovery device 40a in this embodiment is different from the carbon dioxide recovery device 40 in the first embodiment.

[0070] In the carbon dioxide recovery device 40 of the first embodiment, the non-recovered gas line 71 has a non-recovered gas discharge line 72a, and the non-recovered gas valve 61 has a discharge valve 62a. On the other hand, in the carbon dioxide recovery device 40a of this embodiment, the non-recovered gas line 71a has a recycling line 72b, and the non-recovered gas valve 61a has a recycling valve 62b. For this reason, the operation of the valve controller 82a of the control device 80a is different from the operation of the valve controller 82 of the control device 80 of the first embodiment.

[0071] One end of the recycling line 72b is connected to the other end of the discharge line 68, and the other end of the recycling line 72b is connected to the main dry exhaust gas line 25. The aforementioned recycling valve 62b is provided in this recycling line 72b.

[0072] In other words, in this embodiment, a recycling line 72b is provided instead of the non-recovered gas discharge line 72a in the first embodiment, and a recycling valve 62b is provided instead of the discharge valve 62a in the first embodiment.

[0073] Next, the operation of the carbon dioxide capture equipment in this embodiment will be explained according to the flowchart shown in Figure 10.

[0074] The carbon dioxide recovery equipment in this embodiment also performs a pretreatment S10 and a carbon dioxide recovery treatment S20a, similar to the carbon dioxide recovery equipment in the first embodiment. The pretreatment S10 is the same as the pretreatment S10 in the first embodiment. On the other hand, the carbon dioxide recovery treatment S20a is different from the carbon dioxide recovery treatment S20 in the first embodiment.

[0075] The carbon dioxide recovery process S20a in this embodiment, like the carbon dioxide recovery process S20 in the first embodiment, includes an adsorption process S21, a detachment process S22a, and a pressurization process S32. The adsorption process S21 in this embodiment is the same as the adsorption process S21 in the first embodiment. The pressurization process S32 in this embodiment is the same as the pressurization process S32 in the first embodiment. The detachment process S22a in this embodiment, like the detachment process S22 in the first embodiment, includes a control process S23a, a non-recovered gas flow process S27a, and a carbon dioxide recovery process S31. The control process S23a in this embodiment, like the control process S23 in the first embodiment, includes a pressure detection process S24 and a gas flow control process S26a. However, in this embodiment, as described above, a recycling valve 62b is provided instead of the discharge valve 62a in the first embodiment, so the control content in the gas flow control process S26a by the valve controller 82a differs from that of the gas flow control process S26 in the first embodiment. Furthermore, the non-recovered gas distribution process S27a includes a recycling process S29 instead of the non-recovered gas discharge process S28 of the non-recovered gas distribution process S27 in the first embodiment.

[0076] When the adsorption tower 41, which is the target of the detachment process S22a, is vacuum-suctioned by the suction device 50, as described above using Figure 8, the gauge pressure inside the adsorption tower 41 gradually decreases over time, or in other words, the vacuum level inside the adsorption tower 41 gradually increases. The valve controller 82a gives a closing instruction to the recovery gas valve 60 and an opening instruction to the recycle valve 62b when the pressure inside the adsorption tower 41 detected by the pressure gauge 81 is low vacuum relative to the recovery pressure Pc (gas flow control process S26a). As a result, the recovery gas valve 60 is closed and the recycle valve 62b is open, and the gas sucked from the suction device 50 flows into the adsorption tower 41, which is the target of the adsorption process S21, via the recycle line 72b, the recycle valve 62b, and the main dry exhaust gas line 25 (recycling process S29).

[0077] Even when the pressure inside the adsorption tower 41, which is the target of the detachment process S22a, is a lower vacuum than the recovery pressure Pc, the aspirated gas still contains carbon dioxide. Therefore, in this embodiment, when the pressure inside the adsorption tower 41 is a lower vacuum relative to the recovery pressure Pc, the aspirated gas from the suction device 50 is introduced into the adsorption tower 41, which is the target of the adsorption process S21, along with the dry exhaust gas, and the carbon dioxide in this aspirated gas is adsorbed by the carbon dioxide adsorbent 45 inside the adsorption tower 41.

[0078] When the gauge pressure inside the adsorption tower 41 decreases further and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a high vacuum relative to the recovery pressure Pc, the valve controller 82a gives an open command to the recovery gas valve 60 and a close command to the discharge valve 62a (gas flow control process S26a). As a result, the recovery gas valve 60 becomes open and the discharge valve 62a becomes closed, and the gas drawn from the suction device 50 is recovered into the recovery gas tank 63 via the carbon dioxide recovery line 70 and the recovery gas valve 60 (carbon dioxide recovery process S31).

[0079] As described above, in this embodiment as well as in the first embodiment, when the pressure inside the adsorption tower 41 becomes a high vacuum with respect to the recovery pressure Pc, the suction gas from the suction device 50 is guided to the recovery gas tank 63. Therefore, in this embodiment as well as in the first embodiment, high concentrations of carbon dioxide can be recovered. For this reason, in this embodiment as well as in the first embodiment, the increase in the installation area of ​​the equipment and the increase in equipment costs can be suppressed. Furthermore, in this embodiment as well, the time required to recover carbon dioxide from the exhaust gas can be shortened.

[0080] Furthermore, in this embodiment, as described above, if the pressure inside the adsorption tower 41, which is the target of the detachment process S22a, is a lower vacuum than the recovery pressure Pc, the suction gas from the suction device 50 is not released into the atmosphere but is instead allowed to flow into the adsorption tower 41, which is the target of the adsorption process S21. For this reason, in this embodiment, the amount of carbon dioxide released can be reduced compared to the first embodiment.

[0081] "Third Embodiment" A third embodiment of the carbon dioxide capture system will be described with reference to Figures 11 to 13.

[0082] As shown in Figure 11, the carbon dioxide recovery equipment in this embodiment comprises a pretreatment device 10 and a carbon dioxide recovery device 40b, similar to the carbon dioxide recovery equipment in each of the above embodiments. The pretreatment device 10 in this embodiment is the same as the pretreatment device 10 in the first embodiment. On the other hand, the carbon dioxide recovery device 40b in this embodiment differs from the carbon dioxide recovery device 40 in the first embodiment.

[0083] In the carbon dioxide recovery device 40 of the first embodiment, the non-recovered gas line 71 has a non-recovered gas discharge line 72a, and the non-recovered gas valve 61 has a discharge valve 62a. On the other hand, in the carbon dioxide recovery device 40b of this embodiment, the non-recovered gas line 71b has a recycling line 72b in addition to the non-recovered gas discharge line 72a. Also, the non-recovered gas valve 61b of this embodiment has a recycling valve 62b in addition to the discharge valve 62a. For this reason, the operation of the valve controller 82b of the control device 80b is different from the operation of the valve controller 82 of the control device 80 of the first embodiment.

[0084] Similar to the second embodiment, one end of the recycling line 72b is connected to the other end of the discharge line 68, and the other end of the recycling line 72b is connected to the main dry exhaust gas line 25. The recycling valve 62b described above is provided in this recycling line 72b.

[0085] Next, the operation of the carbon dioxide capture equipment in this embodiment will be explained according to the flowchart shown in Figure 12.

[0086] The carbon dioxide recovery equipment in this embodiment also performs a pretreatment S10 and a carbon dioxide recovery treatment S20b, similar to the carbon dioxide recovery equipment in the first embodiment. The pretreatment S10 is the same as the pretreatment S10 in the first embodiment. On the other hand, the carbon dioxide recovery treatment S20b is different from the carbon dioxide recovery treatment S20 in the first embodiment.

[0087] The carbon dioxide recovery process S20b in this embodiment, like the carbon dioxide recovery process S20 in the first embodiment, includes an adsorption process S21, a detachment process S22b, and a pressurization process S32. The adsorption process S21 in this embodiment is the same as the adsorption process S21 in the first embodiment. The pressurization process S32 in this embodiment is the same as the pressurization process S32 in the first embodiment. The detachment process S22b in this embodiment, like the detachment process S22 in the first embodiment, includes a control process S23b, a non-recovered gas flow process S27b, and a carbon dioxide recovery process S31. The control process S23b in this embodiment, like the control process S23 in the first embodiment, includes a pressure detection process S24 and a gas flow control process S26b. However, in this embodiment, as described above, the recovery gas valve 60 has a recycling valve 62b in addition to the discharge valve 62a, so the control content in the gas flow control process S26b by the valve controller 82b differs from that of the gas flow control process S26 in the first embodiment. Furthermore, the non-recovered gas distribution process S27b in this embodiment includes a recycling process S29b in addition to the non-recovered gas discharge process S28b.

[0088] When the adsorption tower 41, which is the target of the detachment process S22b, is vacuum-suctioned by the suction device 50, as shown in Figure 13, the gauge pressure inside the adsorption tower 41 gradually decreases over time, or in other words, the vacuum level inside the adsorption tower 41 gradually increases. The valve controller 82b gives an open command to the discharge valve 62a and a close command to the recycle valve 62b and the recovery gas valve 60 when the pressure inside the adsorption tower 41 detected by the pressure gauge 81 is a lower vacuum than the recycle pressure Pr (gas flow control process S26b). As a result, the recycle valve 62b and the recovery gas valve 60 are closed, the discharge valve 62a is open, and the gas sucked from the suction device 50 is released into the atmosphere via the non-recovered gas discharge line 72a and the discharge valve 62a (non-recovered gas discharge process S28b).

[0089] The aforementioned recycling pressure Pr is the pressure between the recovery pressure Pc and atmospheric pressure, and is closer to atmospheric pressure than the recovery pressure Pc. Furthermore, this recycling pressure Pr is the pressure at which, when the vacuum is lower than this recycling pressure Pr, the carbon dioxide concentration in the gas drawn from the suction unit 50 becomes lower than the carbon dioxide concentration in the dry exhaust gas. This recycling pressure Pr is, for example, -10 kPaG.

[0090] When the gauge pressure inside the adsorption tower 41 decreases further, and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a higher vacuum than the recycling pressure Pr and a lower vacuum than the recovery pressure Pc, the valve controller 82b gives an open command to the recycling valve 62b and a close command to the discharge valve 62a and the recovery gas valve 60 (gas flow control process S26b). As a result, the discharge valve 62a and the recovery gas valve 60 are closed, and the recycling valve 62b is open, and the gas drawn from the suction machine 50 flows into the adsorption tower 41, which is the target of the adsorption process S21, via the recycling line 72b, the recycling valve 62b, and the main dry exhaust gas line 25 (recycling process S29b).

[0091] When the gauge pressure inside the adsorption tower 41 decreases further and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a high vacuum relative to the recovery pressure Pc, the valve controller 82b gives an open command to the recovery gas valve 60 and a close command to the discharge valve 62a and the recycle valve 62b (gas flow control process S26b). As a result, the recovery gas valve 60 is in the open state and the discharge valve 62a and the recycle valve 62b are in the closed state, and the gas drawn from the suction machine 50 is recovered into the recovery gas tank 63 via the carbon dioxide recovery line 70 and the recovery gas valve 60 (carbon dioxide recovery process S31).

[0092] As described above, in this embodiment as well as in the embodiments described above, when the pressure inside the adsorption tower 41 becomes a high vacuum with respect to the recovery pressure Pc, the suction gas from the suction device 50 is guided to the recovery gas tank 63. Therefore, in this embodiment as well as in the embodiments described above, high concentrations of carbon dioxide can be recovered. For this reason, in this embodiment as well as in the embodiments described above, the increase in the installation area of ​​the equipment and the increase in equipment costs can be suppressed. Furthermore, in this embodiment as well, the time required to recover carbon dioxide from the exhaust gas can be shortened.

[0093] Furthermore, in this embodiment, as described above, if the pressure inside the adsorption tower 41, which is the target of the detachment process S22b, is a higher vacuum than the recycling pressure Pr and a lower vacuum than the recovery pressure Pc, the suction gas from the suction device 50 is not released into the atmosphere but is instead allowed to flow into the adsorption tower 41, which is the target of the adsorption process S21. For this reason, in this embodiment, the amount of carbon dioxide released can be reduced compared to the first embodiment.

[0094] Here, if the pressure inside the adsorption tower 41, which is the target of the detachment process S22b, is a lower vacuum than the recycling pressure Pr, the carbon dioxide concentration in the gas drawn in from the suction unit 50 is lower than the carbon dioxide concentration in the dry exhaust gas. Therefore, only a small amount of carbon dioxide is released into the atmosphere. Furthermore, if the gas drawn in from the suction unit 50 were to flow into the adsorption tower 41, which is the target of the adsorption process S21, then a gas with a lower carbon dioxide concentration than the dry exhaust gas would flow into the adsorption tower 41 along with the dry exhaust gas. In this case, the carbon dioxide adsorption efficiency by the carbon dioxide adsorbent 45 inside the adsorption tower 41, which is the target of the adsorption process S21, would decrease. In this embodiment, from the above viewpoint, if the pressure inside the adsorption tower 41, which is the target of the detachment process S22b, is a lower vacuum than the recycling pressure Pr, the gas drawn in from the suction unit 50 is released into the atmosphere.

[0095] "Fourth Embodiment" A fourth embodiment of the carbon dioxide capture system will be described with reference to Figures 14 to 18.

[0096] As shown in Figure 14, the carbon dioxide recovery equipment in this embodiment comprises a pretreatment device 10 and a carbon dioxide recovery device 40c, similar to the carbon dioxide recovery equipment in each of the above embodiments. The pretreatment device 10 in this embodiment is the same as the pretreatment device 10 in the first embodiment. On the other hand, the carbon dioxide recovery device 40c in this embodiment is a modified version of the carbon dioxide recovery device 40b in the third embodiment.

[0097] In this embodiment, the suction machine 50x is a suction machine capable of changing the suction force. Furthermore, in this embodiment, the control device 80c has a suction machine controller 83 that controls the operation of the suction machine 50, in addition to the pressure gauge 81 and valve controller 82b of the control device 80b in the third embodiment.

[0098] Examples of suction machines 50x capable of changing suction force include the suction machine xa shown in Figure 15 and the suction machine 50xb shown in Figure 16. The suction machine 50xa shown in Figure 15 has a suction machine body 51, a motor 52 that drives the suction machine body 51, and an inverter 53 that controls the rotational speed of the motor 52. In this suction machine 50xa, the suction force of the suction machine body 51 changes by changing the rotational speed of the motor 52 using the inverter 53. The suction machine 50xb shown in Figure 16 has a first suction machine body 51a, a first motor 52a that drives the first suction machine body 51a, a first switch 54a that controls the drive of the first motor 52a, a second suction machine body 51b, a second motor 52b that drives the second suction machine body 51b, and a second switch 54b that controls the drive of the second motor 52b. Therefore, by controlling the first switch 54a and the second switch 54b, it is possible to switch from a state in which the first suction unit 51a is operating to a state in which the second suction unit 51b is operating. The suction force of the second suction unit 51b is higher than that of the first suction unit 51a. Therefore, in this suction unit 50xb, the suction force of the suction unit 50xb changes when switching from a state in which the first suction unit 51a is operating to a state in which the second suction unit 51b is operating. For example, the first suction unit 51a and the second suction unit 51b can be vacuum pumps. Note that since the suction force of the first suction unit 51a is lower than that of the second suction unit 51b, the first suction unit 51a may also be a blower.

[0099] The non-recoverable gas line 71b in this embodiment is the same as the non-recoverable gas line 71b in the third embodiment. That is, the non-recoverable gas line 71b in this embodiment also has a non-recoverable gas discharge line 72a and a recycling line 72b. Furthermore, the non-recoverable gas valve 61b in this embodiment is the same as the non-recoverable gas valve 61b in the third embodiment. That is, the non-recoverable gas valve 61b in this embodiment also has a discharge valve 62a and a recycling valve 62b.

[0100] As shown in Figure 17, the carbon dioxide recovery process S20c in this embodiment also includes an adsorption process S21, a detachment process S22c, and a pressurization process S32, similar to the carbon dioxide recovery process S20b in the third embodiment. The adsorption process S21 in this embodiment is the same as the adsorption process S21 in the third embodiment. The pressurization process S32 in this embodiment is also the same as the pressurization process S32 in the third embodiment. The detachment process S22c in this embodiment also includes a control process S23c, a non-recovered gas flow process S27b, and a carbon dioxide recovery process S31, similar to the detachment process S22b in the third embodiment. The control process S23c in this embodiment also includes a pressure detection process S24 and a gas flow control process S26b, similar to the control process S23b in the third embodiment. Furthermore, the control process S23c in this embodiment includes a suction force control process S25. In other words, the control step S23c in this embodiment includes a pressure detection step S24, a suction force control step S25, and a gas flow control step S26b. The non-recovered gas flow step S27b in this embodiment includes a non-recovered gas discharge step S28b and a recycling step S29b, similar to the non-recovered gas flow step S27b in the third embodiment. The carbon dioxide recovery step S31 in this embodiment is the same as the carbon dioxide recovery step S31 in the third embodiment.

[0101] When the inside of the adsorption tower 41, which is the target of the detachment process S22c, is vacuum-suctioned by the suction device 50, as shown in Figure 18, the gauge pressure inside the adsorption tower 41 gradually decreases over time, or in other words, the vacuum level inside the adsorption tower 41 gradually increases. When the pressure inside the adsorption tower 41 detected by the pressure gauge 81 is lower than the recycling pressure Pr, the valve controller 82b gives an open command to the discharge valve 62a and a close command to the recycle valve 62b and the recovery gas valve 60, similar to the third embodiment (gas flow control process S26b). As a result, the recycle valve 62b and the recovery gas valve 60 are closed, the discharge valve 62a is open, and the gas sucked from the suction device 50 is released into the atmosphere via the non-recovered gas discharge line 72a and the discharge valve 62a (non-recovered gas discharge process S28b).

[0102] When the gauge pressure inside the adsorption tower 41 decreases further, and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a higher vacuum than the recycling pressure Pr and a lower vacuum than the recovery pressure Pc, the valve controller 82b gives an open command to the recycling valve 62b and a close command to the discharge valve 62a and the recovery gas valve 60 (gas flow control process S26b). As a result, the discharge valve 62a and the recovery gas valve 60 are closed, and the recycling valve 62b is open, and the gas drawn from the suction machine 50 flows into the adsorption tower 41, which is the target of the adsorption process S21, via the recycling line 72b, the recycling valve 62b, and the main dry exhaust gas line 25 (recycling process S29b).

[0103] When the pressure inside the adsorption tower 41, as detected by the pressure gauge 81, reaches the suction force change pressure Ps, the suction machine controller 83 instructs the suction machine 50x to increase its suction force (suction force control step S25). As a result, the suction force of the suction machine 50x increases, and the pressure inside the adsorption tower 41 drops sharply, as shown in Figure 18.

[0104] The aforementioned suction force change pressure Ps is a pressure between the recovery pressure Pc and atmospheric pressure, and is either a pressure closer to the recovery pressure Pc than atmospheric pressure, or the same pressure as the recovery pressure Pc. This suction force change pressure Ps is, for example, -70 kPaG.

[0105] When the gauge pressure inside the adsorption tower 41 decreases further and the pressure inside the adsorption tower 41 detected by the pressure gauge 81 becomes a high vacuum relative to the recovery pressure Pc, the valve controller 82b gives an open command to the recovery gas valve 60 and a close command to the discharge valve 62a and the recycle valve 62b (gas flow control process S26b). As a result, the recovery gas valve 60 is in the open state and the discharge valve 62a and the recycle valve 62b are in the closed state, and the gas drawn from the suction machine 50x is recovered into the recovery gas tank 63 via the carbon dioxide recovery line 70 and the recovery gas valve 60 (carbon dioxide recovery process S31).

[0106] As described above, in this embodiment as well as in the embodiments described above, when the pressure inside the adsorption tower 41 becomes a high vacuum with respect to the recovery pressure Pc, the suction gas from the suction device 50x is guided to the recovery gas tank 63. Therefore, in this embodiment as well as in the embodiments described above, high concentrations of carbon dioxide can be recovered. For this reason, in this embodiment as well as in the embodiments described above, the increase in the installation area of ​​the equipment and the increase in equipment costs can be suppressed. Furthermore, in this embodiment as well, the time required to recover carbon dioxide from the exhaust gas can be shortened.

[0107] Furthermore, in this embodiment, as in the third embodiment, the non-recovered gas discharge step S28b and the recycling step S29b are performed, so the same effects as in the third embodiment can be obtained.

[0108] Furthermore, in this embodiment, when the suction force change pressure Ps approaches the recovery pressure Pc, or is the same as the recovery pressure Pc, the suction force of the suction device 50x is increased. As a result, after reaching this suction force change pressure Ps, the pressure inside the adsorption tower 41 decreases rapidly, as described above. Therefore, in this embodiment, the execution time of the carbon dioxide recovery process S31 can be shortened compared to the third embodiment.

[0109] Although this embodiment is a modification of the third embodiment, the characteristic configuration of this embodiment may also be applied to the first and second embodiments. That is, in the first and second embodiments, a suction machine 50x with adjustable suction force may be used as the suction machine, and the suction force of this suction machine 50x may be controlled by a suction machine controller 83.

[0110] "Fifth Embodiment" A fifth embodiment of the carbon dioxide capture system will be described with reference to Figures 19 to 21.

[0111] As shown in Figure 19, the carbon dioxide recovery equipment in this embodiment comprises a pretreatment device 10 and a carbon dioxide recovery device 40d, similar to the carbon dioxide recovery equipment in each of the above embodiments. The pretreatment device 10 in this embodiment is the same as the pretreatment device 10 in the first embodiment. On the other hand, the carbon dioxide recovery device 40d in this embodiment is a modified version of the carbon dioxide recovery device 40b in the third embodiment.

[0112] The suction machine 50x in this embodiment, like the suction machine 50x in the fourth embodiment, is a suction machine capable of changing the suction force. Furthermore, the control device 80d in this embodiment has a suction machine controller 83d that controls the operation of the suction machine 50x, in addition to the valve controller 82b of the control device 80b in the third embodiment. However, the control device 80d in this embodiment does not have the pressure gauge 81 of the control device 80b in the third embodiment. Therefore, the control device 80d in this embodiment is a device obtained by removing the pressure gauge 81 from the components of the control device 80c in the fourth embodiment.

[0113] The non-recoverable gas line 71b in this embodiment is the same as the non-recoverable gas line 71b in the third and fourth embodiments. That is, the non-recoverable gas line 71b in this embodiment also has a non-recoverable gas discharge line 72a and a recycling line 72b. Furthermore, the non-recoverable gas valve 61b in this embodiment is the same as the non-recoverable gas valve 61b in the third and fourth embodiments. That is, the non-recoverable gas valve 61b in this embodiment also has a discharge valve 62a and a recycling valve 62b.

[0114] As shown in Figure 20, the carbon dioxide recovery process S20d in this embodiment also includes an adsorption process S21, a detachment process S22d, and a pressurization process S32, similar to the carbon dioxide recovery process S20c in the third embodiment. The adsorption process S21 in this embodiment is the same as the adsorption process S21 in the third embodiment. The pressurization process S32 in this embodiment is also the same as the pressurization process S32 in the third embodiment. The detachment process S22d in this embodiment also includes a control process S23d, a non-recovered gas flow process S27b, and a carbon dioxide recovery process S31, similar to the detachment process S22c in the third embodiment. The control process S23d in this embodiment also includes a gas flow control process S26b, similar to the control process S23b in the third embodiment. Furthermore, the control process S23d in this embodiment includes a suction force control process S25d, similar to the control process S23c in the fourth embodiment. That is, the control process S23d in this embodiment includes a gas flow control process S26b and a suction force control process S25d. In this embodiment, the control step S23d differs from the control steps S23b and S23c in the third and fourth embodiments in that it does not include the pressure detection step S24. The non-recovered gas flow step S27b in this embodiment includes the non-recovered gas discharge step S28b and the recycling step S29b, similar to the non-recovered gas flow step S27b in the third and fourth embodiments. The carbon dioxide recovery step S31 in this embodiment is the same as the carbon dioxide recovery step S31 in the third and fourth embodiments.

[0115] When the inside of the adsorption tower 41, which is the target of the detachment process S22d, is vacuum-suctioned by the suction device 50x, as shown in Figure 21, the gauge pressure inside the adsorption tower 41 gradually decreases over time, or in other words, the degree of vacuum inside the adsorption tower 41 gradually increases.

[0116] In this embodiment, the control operation of the valve controller 82b and the suction machine controller 83d is managed by the time elapsed since the inside of the adsorption tower 41, which is the target of the detachment process S22d, began to be vacuum-suctioned. This time consists of a first time T1 and a second time T2. As shown in Figure 21, the first time T1 is the time elapsed from the start of vacuum suction inside the adsorption tower 41, which is the target of the detachment process S22d, until the pressure inside the adsorption tower 41 is assumed to have reached the aforementioned recycling pressure Pr. The second time T2 is the time elapsed from the start of vacuum suction inside the adsorption tower 41, which is the target of the detachment process S22d, until the pressure inside the adsorption tower 41 is assumed to have reached the aforementioned suction force change pressure Ps. Therefore, in this embodiment, the valve controller 82b and the suction machine controller 83d operate on the assumption that the pressure inside the adsorption tower 41 is a vacuum lower than the recycling pressure Pr until the first time T1 has elapsed. Furthermore, in this embodiment, the valve controller 82b and the suction machine controller 83d operate assuming that the pressure inside the adsorption tower 41 is a higher vacuum than the recycling pressure Pr and a lower vacuum than the recovery pressure Pc after the first time T1 has elapsed and until the second time T2 has elapsed. Moreover, in this embodiment, the valve controller 82b and the suction machine controller 83d operate assuming that the pressure inside the adsorption tower 41 is a higher vacuum than the recovery pressure Pc after the second time T2 has elapsed.

[0117] The valve controller 82b instructs the discharge valve 62a to open and the recycle valve 62b and the recovery gas valve 60 to close until the first time T1 has elapsed since the start of vacuum suction inside the adsorption tower 41, which is the target of the detachment process S22d (gas flow control process S26b). As a result, the recycle valve 62b and the recovery gas valve 60 are closed and the discharge valve 62a is open, and the gas drawn in from the suction machine 50x is released into the atmosphere via the non-recovered gas discharge line 72a and the discharge valve 62a (non-recovered gas discharge process S28b). In other words, the non-recovered gas discharge process S28b is executed in the same manner as in the third and fourth embodiments until it is assumed that the pressure inside the adsorption tower 41, which is the target of the detachment process S22d, has reached the recycling pressure Pr.

[0118] When the second time T2 has elapsed since the inside of the adsorption tower 41, which is the target of the detachment process S22d, began to be vacuum-suctioned, the suction machine controller 83d instructs the suction machine 50x to increase its suction force (suction force control process S25d). As a result, the suction force of the suction machine 50x increases, and the pressure inside the adsorption tower 41 drops sharply, as shown in Figure 21. In other words, when it is assumed that the inside of the adsorption tower 41, which is the target of the detachment process S22d, has reached the suction force change pressure Ps, the suction force control process S25d is executed.

[0119] The valve controller 82b gives an open command to the recycle valve 62b and a close command to the discharge valve 62a and the recovery gas valve 60 from after the first time T1 has elapsed since the inside of the adsorption tower 41, which is the target of the detachment process S22d, began to be vacuum-suctioned, until the second time T2 has elapsed and the suction force has been increased (gas flow control process S26b). As a result, the discharge valve 62a and the recovery gas valve 60 are in a closed state, and the recycle valve 62b is in an open state, and the suction gas from the suction machine 50x flows into the adsorption tower 41, which is the target of the adsorption process S21, via the recycle line 72b, the recycle valve 62b, and the main dry exhaust gas line 25 (recycling process S29b). In other words, as long as the inside of the adsorption tower 41, which is the target of the detachment process S22d, is assumed to be at a vacuum higher than the recycle pressure Pr and lower than the recovery pressure Pc, the recycling process S29b is executed, similar to the third and fourth embodiments.

[0120] When the suction force is increased after the second time T2 has elapsed since the start of vacuum suction inside the adsorption tower 41, which is the target of the detachment process S22d, the valve controller 82b gives an open command to the recovery gas valve 60 and a close command to the discharge valve 62a and the recycle valve 62b (gas flow control process S26b). As a result, the recovery gas valve 60 is in the open state, and the discharge valve 62a and the recycle valve 62b are in the closed state, and the gas drawn from the suction machine 50x is recovered into the recovery gas tank 63 via the carbon dioxide recovery line 70 and the recovery gas valve 60 (carbon dioxide recovery process S31). In other words, when it is assumed that the recovery pressure Pc has been reached inside the adsorption tower 41, which is the target of the detachment process S22d, the carbon dioxide recovery process S31 is executed.

[0121] As described above, in this embodiment, when it is assumed that the pressure inside the adsorption tower 41 has become a high vacuum with respect to the recovery pressure Pc, the suction gas from the suction device 50x is guided to the recovery gas tank 63. Therefore, in this embodiment as well as in the above embodiments, high concentrations of carbon dioxide can be recovered. For this reason, in this embodiment as well as in the above embodiments, the increase in the installation area of ​​the equipment and the increase in equipment costs can be suppressed. Furthermore, in this embodiment as well, the time required to recover carbon dioxide from the exhaust gas can be shortened.

[0122] Furthermore, in this embodiment, as in the third embodiment, the non-recovered gas discharge step S28b and the recycling step S29b are performed, so the same effects as in the third embodiment can be obtained.

[0123] Furthermore, in this embodiment, once the second time T2, which is assumed to have reached the suction force change pressure Ps, has elapsed, the suction force by the suction device 50x is increased, and from this point onward, as described above, the pressure inside the adsorption tower 41 decreases rapidly. For this reason, in this embodiment, similar to the fourth embodiment, the execution time of the carbon dioxide recovery process S31 can be shortened compared to the third embodiment.

[0124] Furthermore, in this embodiment, a pressure gauge 81 is not required, unlike in the fourth embodiment, so equipment costs can be reduced compared to the fourth embodiment.

[0125] Although this embodiment is a modification of the third embodiment, the characteristic configuration of this embodiment may also be applied to the first and second embodiments. That is, in the first and second embodiments, a suction machine 50x with adjustable suction force may be used as the suction machine, and the suction force of this suction machine 50x may be controlled by a suction machine controller 83d.

[0126] For example, in a configuration in which the characteristic configuration of this embodiment is applied to the first embodiment, the unrecovered gas release step S28 is executed when it is assumed that the pressure inside the adsorption tower 41 is a vacuum lower than the recovery pressure Pc, and the carbon dioxide recovery step S31 is executed when it is assumed that the pressure inside the adsorption tower 41 is a vacuum higher than the recovery pressure Pc.

[0127] Furthermore, in a configuration in which the characteristic configuration of this embodiment is applied to the second embodiment, the recycling process S29 is executed when it is assumed that the pressure inside the adsorption tower 41 is a lower vacuum than the recovery pressure Pc, and the carbon dioxide recovery process S31 is executed when it is assumed that the pressure inside the adsorption tower 41 is a higher vacuum than the recovery pressure Pc.

[0128] "Variations" In all of the above embodiments, the carbon dioxide recovery equipment is equipped with a pretreatment device 10. However, if the amount of moisture in the exhaust gas from the exhaust gas source 1 is extremely low, the pretreatment device 10 may be omitted. In this case, one end of the main dry exhaust gas line 25 in each of the above embodiments is connected to the exhaust gas source 1, and a blower 16 is provided in this main dry exhaust gas line 25.

[0129] In each of the embodiments described above, porous structures are used as carbon dioxide adsorbents 45 in the adsorption tower 41. However, as carbon dioxide adsorbents, a large number of spherical objects (beads) with a small diameter (e.g., 0.1 mm to 5.0 mm), a large number of pellets with a small maximum size (e.g., 0.1 mm to 5.0 mm), or powder may also be used. However, if a large number of spherical objects, pellets, or powder are used as carbon dioxide adsorbents, they may become fluidized in the flow within the adsorption tower 41 and flow out of the adsorption tower 41. On the other hand, when these carbon dioxide adsorbents are used, even if exhaust gas is sent into the adsorption tower 41 when it is under high vacuum, the exhaust gas will not blow through between the large number of carbon dioxide adsorbents. For this reason, when these carbon dioxide adsorbents are used, the pressurization step after the detachment step may be omitted.

[0130] In each of the above embodiments, the recovery pressure Pc is -80 kPaG. However, depending on the desired concentration of carbon dioxide in the aspirated gas, the recovery pressure Pc may be set to any value between -75 and -95 kPaG.

[0131] Although embodiments of this disclosure have been described in detail above, this disclosure is not limited to the embodiments described above. Various additions, modifications, substitutions, and partial deletions are possible, provided that they do not depart from the conceptual idea and spirit of the present invention derived from the claims and their equivalents.

[0132] "Addendum" The carbon dioxide capture equipment in the above embodiments and modifications can be understood, for example, as follows.

[0133] (1) The carbon dioxide capture equipment in the first embodiment is: A carbon dioxide recovery system capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide comprises: an adsorption tower 41 filled with carbon dioxide adsorbent material 45 formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure; a blower 16 that sends the exhaust gas into the adsorption tower 41; suction machines 50, 50x that vacuum-suction the inside of the adsorption tower 41; a discharge line 68 connected to the discharge port of the suction machines 50, 50x; a carbon dioxide recovery line 70 connected to the discharge line 68; a recovery gas valve 60 provided in the carbon dioxide recovery line 70; and the discharge The system includes a non-recoverable gas line 71 connected to line 68, non-recoverable gas valves 61, 61a, 61b provided in the non-recoverable gas line 71, and control devices 80, 80a, 80b, 80c, 80d that close the recovery gas valve 60 and open the non-recoverable gas valves 61, 61a, 61b when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure Pc, and close the non-recoverable gas valves 61, 61a, 61b and open the recovery gas valve 60 when the pressure inside the adsorption tower 41 is high vacuum or is assumed to be high vacuum relative to the recovery pressure Pc.

[0134] The inventors vacuumed the inside of the adsorption tower 41 and analyzed the gas components in the aspirated gas according to the pressure inside the adsorption tower 41 at that time. Through this analysis, the inventors discovered the following phenomenon: When the vacuum level inside the adsorption tower 41 is low, the nitrogen concentration in the aspirated gas is high and the carbon dioxide concentration in the aspirated gas is low. As the vacuum level inside the adsorption tower 41 is increased, the nitrogen concentration in the aspirated gas gradually decreases and the carbon dioxide concentration in the aspirated gas increases. This phenomenon is thought to be because the adsorption capacity of carbon dioxide to the carbon dioxide adsorbent 45 is higher than the adsorption capacity of nitrogen to the carbon dioxide adsorbent 45.

[0135] Based on the above phenomena, the inventor conceived of the carbon dioxide recovery equipment in the first embodiment. In this embodiment, when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure Pc, the aspirated gas is not recovered into a tank or the like. However, when the pressure inside the adsorption tower 41 is high vacuum or is assumed to be high vacuum relative to the recovery pressure Pc, the aspirated gas is recovered into a tank or the like. Therefore, in this embodiment, high concentrations of carbon dioxide can be recovered.

[0136] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without providing a first-stage adsorption tower and a second-stage adsorption tower, as described above, thus reducing the number of components in the system. Therefore, in this embodiment, an increase in the installation area of ​​the system and an increase in equipment costs can be suppressed.

[0137] Furthermore, in this embodiment, high concentrations of carbon dioxide can be recovered without performing the adsorption process in two stages, thus shortening the time required to recover carbon dioxide from exhaust gas.

[0138] (2) The carbon dioxide capture equipment in the second embodiment is: In the carbon dioxide recovery equipment according to the first embodiment described above, the control devices 80, 80a, 80b, and 80c include a pressure gauge 81 capable of detecting the pressure inside the adsorption tower 41, and valve controllers 82, 82a, and 82b that control the opening and closing of the recovery gas valve 60 and the non-recovery gas valves 61, 61a, and 61b based on the pressure detected by the pressure gauge 81.

[0139] (3) The carbon dioxide recovery equipment in the third embodiment is In the carbon dioxide recovery equipment according to the second embodiment, the control device 80c has a suction machine controller 83 that controls the operation of the suction machine 50x based on the pressure detected by the pressure gauge 81. When the pressure detected by the pressure gauge 81 becomes higher than the recovery pressure Pc and closer to the recovery pressure Pc than atmospheric pressure, or the suction force change pressure Ps which is the recovery pressure Pc, the suction machine controller 83 operates the suction machine 50x to increase its suction force.

[0140] In this embodiment, when the pressure inside the adsorption tower 41 reaches the suction force change pressure Ps, the suction force of the suction device 50x increases. Therefore, in this embodiment, the pressure inside the adsorption tower 41 decreases rapidly from this point onward. Thus, in this embodiment, the pressure inside the adsorption tower 41 decreases rapidly at the start of the carbon dioxide recovery process S31, and the execution time of this carbon dioxide recovery process S31 can be shortened.

[0141] (4) The carbon dioxide capture equipment in the fourth embodiment is: In the carbon dioxide recovery equipment according to the first embodiment, the control device 80d includes a suction device controller 83d that controls the operation of the suction device 50x, and a valve controller 82b that controls the opening and closing of the recovery gas valve 60 and the non-recovery gas valve 61b. The suction device controller 83d operates the suction device 50x to increase its suction force after a predetermined time T2 has elapsed since the suction device 50x has created a vacuum inside the adsorption tower 41. The valve controller 82b closes the recovery gas valve 60 and opens the non-recovered gas valve 61b when the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc before the suction machine controller 83d increases the suction force of the suction machine 50x, and closes the non-recovered gas valve 61b and opens the recovery gas valve 60 when the pressure inside the adsorption tower 41 is higher than the recovery pressure Pc after the suction machine controller 83d increases the suction force of the suction machine 50x.

[0142] In this embodiment, after a predetermined time T2 has elapsed since the adsorption tower 41 was vacuum-suctioned by the suction device 50x, the suction force of the suction device 50x increases. Therefore, in this embodiment, the pressure inside the adsorption tower 41 decreases rapidly from this point onward. Thus, in this embodiment, similar to the third embodiment, it becomes possible to rapidly decrease the pressure inside the adsorption tower 41 at the start of the carbon dioxide recovery process S31, thereby shortening the execution time of the carbon dioxide recovery process S31.

[0143] (5) The carbon dioxide capture equipment in the fifth embodiment is: In the carbon dioxide recovery equipment according to any one of the first to fourth embodiments described above, the non-recovered gas line 71 has a non-recovered gas discharge line 72a with an open end. The non-recovered gas valve 61 has a discharge valve 62a provided in the non-recovered gas discharge line 72a. The control devices 80, 80b, 80c, and 80d open the discharge valve 62a when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum with respect to the recovery pressure Pc, and close the discharge valve 62a when the pressure inside the adsorption tower 41 is high vacuum or is assumed to be high vacuum with respect to the recovery pressure Pc.

[0144] In this embodiment, when the pressure inside the adsorption tower 41 is low vacuum with respect to the recovery pressure Pc, or when it is assumed to be low vacuum, the release valve 62a opens, and the aspirated gas drawn in by the suction devices 50, 50x is released into the atmosphere via the non-recovered gas release line 72a and the release valve 62a. Also in this embodiment, when the pressure inside the adsorption tower 41 is high vacuum with respect to the recovery pressure Pc, or when it is assumed to be high vacuum, the release valve 62a closes, the recovery gas valve 60 opens, and the aspirated gas is recovered into a tank or the like via the carbon dioxide recovery line 70 and the recovery gas valve 60.

[0145] (6) The carbon dioxide capture equipment in the sixth embodiment is: In the carbon dioxide recovery equipment according to any one of the first to fourth embodiments described above, a pretreatment device 10 capable of removing moisture contained in the exhaust gas is further provided. The pretreatment device 10 includes a dehumidifying tower 11 capable of removing moisture contained in the exhaust gas from the blower 16, and a dry exhaust gas line 23 that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower 11, to the adsorption tower 41. The non-recovered gas line 71 has a recycling line 72b connected to the dry exhaust gas line 23. The non-recovered gas valve 61a has a recycling valve 62b provided in the recycling line 72b. The control devices 80a, 80b, 80c, and 80d open the recycling valve 62b when the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc or is assumed to be lower than the vacuum, and close the recycling valve 62b when the pressure inside the adsorption tower 41 is higher than the recovery pressure Pc or is assumed to be higher than the vacuum.

[0146] In this embodiment, when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum with respect to the recovery pressure Pc, the recycle valve 62b opens, and the aspirated gas drawn in by the suction devices 50, 50x is sent to the adsorption tower 41 in the carbon dioxide adsorption process S21 via the recycle line 72b, the recycle valve 62b, and the dry exhaust gas line 23. Also in this embodiment, when the pressure inside the adsorption tower 41 is high vacuum or is assumed to be high vacuum with respect to the recovery pressure Pc, the recycle valve 62b closes, the recovery gas valve 60 opens, and the aspirated gas is recovered in a tank or the like via the carbon dioxide recovery line 70 and the recovery gas valve 60. Even when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum with respect to the recovery pressure Pc, carbon dioxide is still contained in the aspirated gas. In this embodiment, when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum with respect to the recovery pressure Pc, the aspirated gas is not released into the atmosphere, but is sent to the adsorption tower 41 in the carbon dioxide adsorption process S21. Therefore, in this embodiment, the amount of carbon dioxide emitted can be reduced.

[0147] (7) The carbon dioxide capture equipment in the seventh embodiment is: In the carbon dioxide recovery equipment according to any one of the first to fourth embodiments described above, a pretreatment device 10 capable of removing moisture contained in the exhaust gas is further provided. The pretreatment device 10 includes a dehumidifying tower 11 capable of removing moisture contained in the exhaust gas from the blower 16, and a dry exhaust gas line 23 that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower 11, to the adsorption tower 41. The non-recovered gas line 71b includes a non-recovered gas discharge line 72a with an open end and a recycle line 72b connected to the dry exhaust gas line 23. The non-recovered gas valve 61b includes a discharge valve 62a provided in the non-recovered gas discharge line 72a and a recycle valve 62b provided in the recycle line 72b. The control devices 80b, 80c, and 80d open the discharge valve 62a and close the recycle valve 62b when the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc and lower than the recycling pressure Pr, which is closer to atmospheric pressure than the recovery pressure Pc, or when it is assumed to be lower than the recycling pressure Pr. The control devices 80b, 80c, and 80d close the discharge valve 62a and open the recycle valve 62b when the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc and higher than the recycling pressure Pr, or when it is assumed to be lower than the recovery pressure Pc and higher than the recycling pressure Pr. The control devices 80b, 80c, and 80d close the discharge valve 62a and the recycle valve 62b when the pressure inside the adsorption tower 41 is higher than the recovery pressure Pc or when it is assumed to be higher than the recovery pressure Pc.

[0148] In this embodiment, when the pressure inside the adsorption tower 41 is low vacuum relative to the recycling pressure Pr, or is assumed to be lower vacuum than the recycling pressure Pr, the discharge valve 62a opens and the recycling valve 62b closes, and the aspirated gas drawn in by the suction devices 50, 50x is released into the atmosphere via the non-recovered gas discharge line 72a and the discharge valve 62a. Also in this embodiment, when the pressure inside the adsorption tower 41 is lower vacuum than the recovery pressure Pc and higher vacuum than the recycling pressure Pr, or is assumed to be lower vacuum than the recovery pressure Pc and higher vacuum than the recycling pressure Pr, the discharge valve 62a closes and the recycling valve 62b opens, and the aspirated gas drawn in by the suction devices 50, 50x is sent to the adsorption tower 41 during the carbon dioxide adsorption process S21 via the recycling line 72b, the recycling valve 62b, and the dry exhaust gas line 23. Furthermore, in this embodiment, when the pressure inside the adsorption tower 41 is a high vacuum or is assumed to be a high vacuum with respect to the recovery pressure Pc, the discharge valve 62a and the recycle valve 62b close, the recovery gas valve 60 opens, and the aspirated gas is recovered into a tank or the like via the carbon dioxide recovery line 70 and the recovery gas valve 60.

[0149] Even when the pressure inside the adsorption tower 41 is low vacuum relative to the recovery pressure Pc, or is assumed to be low vacuum, the aspirated gas contains carbon dioxide. In this embodiment, when the pressure inside the adsorption tower 41 is lower vacuum than the recovery pressure Pc and higher vacuum than the recycling pressure Pr, or when it is assumed to be lower vacuum than the recovery pressure Pc and higher vacuum than the recycling pressure Pr, the aspirated gas is not released into the atmosphere, and this aspirated gas is sent to the adsorption tower 41 in the carbon dioxide adsorption process S21. Therefore, in this embodiment, the amount of carbon dioxide released can be reduced. Also, in this embodiment, the carbon dioxide concentration in the gas sent to the adsorption tower 41 in the carbon dioxide adsorption process S21 via the recycling line 72b is lower than the carbon dioxide concentration in the gas recovered in the tank, etc., but higher than the carbon dioxide concentration in the gas released into the atmosphere. Therefore, gas with a high carbon dioxide concentration is sent into the adsorption tower 41 in the carbon dioxide adsorption process S21. For this reason, in this embodiment, the adsorption rate of carbon dioxide by the carbon dioxide adsorbent 45 in the adsorption tower 41 in the carbon dioxide adsorption process S21 can be increased.

[0150] (8) The carbon dioxide capture equipment in the eighth embodiment is: The carbon dioxide adsorbent in any one of the first to seventh embodiments is a zeolite.

[0151] (9) The carbon dioxide capture equipment in the ninth embodiment is: In the carbon dioxide recovery equipment according to the eighth embodiment described above, the recovery pressure Pc is -75 to -95 kPaG.

[0152] (10) The carbon dioxide capture equipment in the tenth embodiment is In the carbon dioxide recovery equipment according to any one of the first to ninth embodiments described above, the carbon dioxide adsorbent 45 is a porous structure having a plurality of through holes 46 that penetrate each other in the same direction.

[0153] In this embodiment, since the carbon dioxide adsorbent 45 is a porous structure, it does not become fluid due to the gas flow within the adsorption tower 41, and the outflow of the carbon dioxide adsorbent 45 from within the adsorption tower 41 can be avoided.

[0154] The carbon dioxide capture methods in the above embodiments and modifications can be understood, for example, as follows. (11) The carbon dioxide capture method in the eleventh aspect is: In a carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, the method involves introducing the exhaust gas into an adsorption tower 41, which is filled with a carbon dioxide adsorbent 45 formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and performing an adsorption step S21 in which the carbon dioxide adsorbent adsorbs the carbon dioxide in the exhaust gas, and performing detachment steps S22, S22a, S22b, S22c, S22d in which the inside of the adsorption tower 41 is vacuum-suctioned to detach the carbon dioxide adsorbed on the carbon dioxide adsorbent from the carbon dioxide adsorbent. The detachment steps S22, S22a, S22b, S22c, and S22d include a carbon dioxide recovery step S31 that guides the gas from the adsorption tower 41 as recovered gas to the recovery gas tank 63, non-recovered gas flow steps S27, S27a, and S27b that guide the gas from the adsorption tower 41 as non-recovered gas to a location other than the recovery gas tank 63, and control steps S23, S23a, S23b, S23c, and S23d that control the execution of the carbon dioxide recovery step S31 and the non-recovered gas flow steps S27, S27a, and S27b. In the control steps S23, S23a, S23b, S23c, and S23d, the carbon dioxide recovery step S31 is executed when the pressure inside the adsorption tower 41 is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure Pc, and the non-recovered gas flow steps S27, S27a, and S27b are executed when the pressure inside the adsorption tower 41 is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure Pc.

[0155] In this embodiment, the same effects as the carbon dioxide recovery equipment in the first embodiment can be obtained. That is, in this embodiment as well, high concentrations of carbon dioxide can be recovered without providing a first-stage adsorption tower and a second-stage adsorption tower, as in the equipment described in Non-Patent Document 1. Furthermore, in this embodiment as well, the time required to recover carbon dioxide from exhaust gas can be shortened.

[0156] (12) The carbon dioxide capture method in the twelfth embodiment is: In the carbon dioxide recovery method according to the eleventh embodiment described above, the control steps S23, S23a, S23b, S23c include a pressure detection step S24 for detecting the pressure inside the adsorption tower 41, and gas flow control steps S26, S26a, S26b for causing one of the carbon dioxide recovery steps S31 and the non-recovered gas flow steps S27, S27a, S27b to be executed based on the pressure detected in the pressure detection step S24.

[0157] (13) The carbon dioxide capture method in the thirteenth aspect is: In the carbon dioxide recovery method according to the twelfth embodiment, the control step S23c includes a suction force control step S25 that controls the suction force used to vacuum-suction the inside of the adsorption tower 41. In the suction force control step S25, when the pressure detected in the pressure detection step S24 becomes higher than the recovery pressure Pc and closer to the recovery pressure Pc than atmospheric pressure, or when it becomes a suction force change pressure Ps which is the recovery pressure Pc, the suction force is increased.

[0158] In this embodiment, similar to the carbon dioxide recovery equipment in the third embodiment, the execution time of the carbon dioxide recovery process S31 can be shortened.

[0159] (14) The carbon dioxide capture method in the fourteenth embodiment is: In the carbon dioxide recovery method according to the eleventh embodiment, the control step S23d includes a suction force control step S25d that controls the suction force for vacuum suction inside the adsorption tower 41, and a gas flow control step S26b that causes one of the carbon dioxide recovery step S31 and the non-recovered gas flow step S27 to be executed. In the suction force control step S25d, the suction force is increased after a predetermined time T2 has elapsed since vacuum suction started inside the adsorption tower 41. In the gas flow control step S26b, the non-recovered gas flow step S27 is executed assuming that the pressure inside the adsorption tower 41 is a lower vacuum than the recovery pressure Pc before the suction force is increased in the suction force control step S25d, and the carbon dioxide recovery step S31 is executed assuming that the pressure inside the adsorption tower 41 is a higher vacuum than the recovery pressure Pc after the suction force is increased in the suction force control step S25d.

[0160] In this embodiment, similar to the carbon dioxide recovery equipment in the fourth embodiment, the execution time of the carbon dioxide recovery process S31 can be shortened.

[0161] (15) The carbon dioxide capture method in the fifteenth embodiment is: In the carbon dioxide recovery method according to any one of the eleventh to fourteenth embodiments, the unrecovered gas flow steps S27, S27b include unrecovered gas release steps S28, S28b for releasing the unrecovered gas into the atmosphere. In the control steps S23, S23b, S23c, S23d, the unrecovered gas release steps S28, S28b are executed when the pressure inside the adsorption tower 41 is at or is assumed to be at a low vacuum with respect to the recovery pressure Pc, and the unrecovered gas release steps S28, S28b are not executed when the pressure inside the adsorption tower 41 is at or is assumed to be at a high vacuum with respect to the recovery pressure Pc.

[0162] In this embodiment, the same effects as the carbon dioxide capture equipment in the fifth embodiment can be obtained.

[0163] (16) The carbon dioxide capture method in the sixteenth aspect is: In the carbon dioxide recovery method according to any one of the eleventh to fourteenth embodiments, a pretreatment S10 is further performed to remove moisture contained in the exhaust gas. The pretreatment S10 includes a dehumidification step S11 in which the exhaust gas is sent into a dehumidification tower 11 to remove moisture from the exhaust gas, and the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower 11, is guided to the adsorption tower 41. The non-recovered gas flow steps S27a, S27b include recycling steps S29, S29b in which the non-recovered gas is mixed into the dry exhaust gas. In the control steps S23a, S23b, S23c, S23d, the recycling steps S29, S29b are executed when the pressure inside the adsorption tower 41 is low vacuum or is assumed to be low vacuum with respect to the recovery pressure Pc, and the recycling steps S29, S29b are not executed when the pressure inside the adsorption tower 41 is high vacuum or is assumed to be high vacuum with respect to the recovery pressure Pc.

[0164] In this embodiment, similar to the carbon dioxide capture equipment in the sixth embodiment, the amount of carbon dioxide emitted can be reduced.

[0165] (17) The carbon dioxide capture method in the seventeenth aspect is: In the carbon dioxide recovery method according to any one of the eleventh to fourteenth embodiments described above, a pretreatment S10 is further performed to remove moisture contained in the exhaust gas. The pretreatment S10 includes a dehumidification step S11 in which the exhaust gas is sent into a dehumidification tower 11 to remove moisture from the exhaust gas and the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower 11, is guided to the adsorption tower 41. The non-recovered gas flow steps S27b, S27c, and S27d include a non-recovered gas release step S28b in which the non-recovered gas is released into the atmosphere and a recycling step S29b in which the non-recovered gas is mixed into the dry exhaust gas. In the control steps S23b, S23c, and S23d, if the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc and lower than the recycling pressure Pr, which is closer to atmospheric pressure than the recovery pressure Pc, or if it is assumed to be lower than the recycling pressure Pr, the unrecovered gas release step S28b is executed and the recycling step S29b is not executed. In the control steps S23b, S23c, and S23d, if the pressure inside the adsorption tower 41 is lower than the recovery pressure Pc and higher than the recycling pressure Pr, or if it is assumed to be lower than the recovery pressure Pc and higher than the recycling pressure Pr, the unrecovered gas release step S28b is not executed and the recycling step S29b is executed. In the control steps S23b, S23c, and S23d, if the pressure inside the adsorption tower 41 is higher than the recovery pressure Pc, or if it is assumed to be higher than the recovery pressure Pc, the non-recovered gas discharge step S28b and the recycling step S29b are not executed.

[0166] In this embodiment, similar to the carbon dioxide capture equipment in the seventh embodiment, the amount of carbon dioxide emitted can be reduced. Furthermore, in this embodiment, the carbon dioxide adsorption rate by the carbon dioxide adsorbent 45 in the adsorption tower 41 during the carbon dioxide adsorption process S21 can be increased.

[0167] (18) The carbon dioxide capture method in the eighteenth aspect is: In the carbon dioxide recovery method according to any one of the eleventh to seventeenth embodiments, zeolite is used as the carbon dioxide adsorbent.

[0168] (19) The carbon dioxide capture method in the nineteenth embodiment is: In the carbon dioxide recovery method according to the eighteenth embodiment described above, the recovery pressure Pc is -75 to -95 kPaG. [Explanation of Symbols]

[0169] 1: Source of exhaust gas 10: Pretreatment device 11:Dehumidification tower 11a: First dehumidification tower 11b:Second dehumidification tower 12: Container 13:First mouth 14:Second mouth 15: Water adsorbent 16: Blower 17: Dehumidifying Vacuum Pump 20: Exhaust gas line 21: Main exhaust gas line 22a: First exhaust gas line 22b: Second exhaust gas line 23: Dry exhaust gas line 24a: Dehumidification side first drying exhaust gas line 24b: Dehumidification side second drying exhaust gas line 25: Main dry exhaust gas line 26a: Recovery side first dry exhaust gas line 26b: Recovery side second dry exhaust gas line 26c: Recovery side third dry exhaust gas line 27: Moisture-rich gas line 28a: First moisture-rich gas line 28b: Second moisture-rich gas line 29: Main water-rich gas line 30: Off-gas line 31a: Recovery side first off-gas line 31b: Recovery side second off-gas line 31c: Recovery side third off-gas line 32: Main off-gas line 33a: Dehumidification side first off-gas line 33b: Dehumidification side second off-gas line 35a: First exhaust gas valve 35b: Second exhaust gas valve 36a: Dehumidification side first drying exhaust gas valve 36b: Dehumidification side second drying exhaust gas valve 37a: First moisture-rich gas valve 37b: Second moisture-rich gas valve 38a: Dehumidification side first off-gas valve 38b: Dehumidification side second off-gas valve 40, 40a, 40b, 40c, 40d: Carbon dioxide capture device 41:Adsorption tower 41a: First adsorption tower 41b:Second adsorption tower 41c: Third adsorption tower 42: Container 43:First mouth 44:Second mouth 45: Carbon dioxide adsorbent 46: Through hole 50,50x,50xa,50xb:Suction machine 51:Suction machine body 51a: First suction machine body 51b:Second suction machine body 52: Motor 52a: First Motor 52b: Second motor 53: Inverter 54a: First switch 54b: Second switch 56a: Recovery side first dry exhaust gas valve 56b: Recovery side second dry exhaust gas valve 56c: Recovery side third dry exhaust gas valve 57a: First suction valve 57b: Second suction valve 57c: Third suction valve 58a: Recovery side first off-gas valve 58b: Recovery side second off-gas valve 58c: Recovery side third off-gas valve 60: Recovery gas valve 61, 61a, 61b: Non-recoverable gas valves 62a: Discharge valve 62b: Recycle valve 63: Recovery gas tank 65: Suction line 66a: First suction line 66b: Second suction line 66c: Third suction line 67: Main suction line 68: Discharge line 70: Carbon dioxide capture line 71, 71a, 71b: Non-recoverable gas lines 72a: Non-recoverable gas discharge line 72b: Recycling line 80, 80a, 80b, 80c, 80d: Control device 81: Pressure gauge 82, 82a, 82b: Valve controllers 83,83d: Suction machine controller

Claims

1. A carbon dioxide recovery system capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption tower is filled with carbon dioxide adsorbent material, which is made of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, A blower that sends the exhaust gas into the adsorption tower, A suction device for vacuum suction inside the adsorption tower, The discharge line connected to the discharge port of the suction device, A carbon dioxide recovery line connected to the aforementioned discharge line, A recovery gas valve installed in the carbon dioxide recovery line, A non-recoverable gas line connected to the aforementioned discharge line, A non-recoverable gas valve is provided in the aforementioned non-recoverable gas line, A control device that closes the recovery gas valve and opens the non-recovered gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure, and closes the non-recovered gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum relative to the recovery pressure, Equipped with, The control device includes a pressure gauge capable of detecting the pressure inside the adsorption tower, a valve controller that controls the opening and closing of the recovery gas valve and the non-recovery gas valve based on the pressure detected by the pressure gauge, and a suction machine controller that controls the operation of the suction machine based on the pressure detected by the pressure gauge. The suction machine controller operates the suction machine to increase its suction force when the pressure detected by the pressure gauge is higher than the recovery pressure and closer to the recovery pressure than atmospheric pressure, or when the suction force change pressure is the recovery pressure. Carbon dioxide capture equipment.

2. A carbon dioxide recovery system capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption tower is filled with carbon dioxide adsorbent material, which is made of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, A blower that sends the exhaust gas into the adsorption tower, A suction device for vacuum suction inside the adsorption tower, The discharge line connected to the discharge port of the suction device, A carbon dioxide recovery line connected to the aforementioned discharge line, A recovery gas valve installed in the carbon dioxide recovery line, A non-recoverable gas line connected to the aforementioned discharge line, A non-recoverable gas valve is provided in the aforementioned non-recoverable gas line, A control device that closes the recovery gas valve and opens the non-recovered gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure, and closes the non-recovered gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum relative to the recovery pressure, Equipped with, The control device comprises a suction machine controller that controls the operation of the suction machine, and a valve controller that controls the opening and closing of the recovery gas valve and the non-recovery gas valve. The suction machine controller operates the suction machine to increase its suction force after a predetermined time has elapsed since the suction machine vacuum-filled the inside of the adsorption tower. The valve controller closes the recovery gas valve and opens the non-recovered gas valve when the pressure inside the adsorption tower is lower than the recovery pressure before the suction controller increases the suction force of the suction machine, and closes the non-recovered gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is higher than the recovery pressure after the suction controller increases the suction force of the suction machine. Carbon dioxide capture equipment.

3. In the carbon dioxide recovery equipment according to claim 1 or 2, The non-recoverable gas line has a non-recoverable gas discharge line with an open end, The non-recoverable gas valve has a discharge valve provided in the non-recoverable gas discharge line, The control device opens the release valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum with respect to the recovery pressure, and closes the release valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum with respect to the recovery pressure. Carbon dioxide capture equipment.

4. A carbon dioxide recovery system capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption tower is filled with carbon dioxide adsorbent material, which is made of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, A blower that sends the exhaust gas into the adsorption tower, A suction device for vacuum suction inside the adsorption tower, The discharge line connected to the discharge port of the suction device, A carbon dioxide recovery line connected to the aforementioned discharge line, A recovery gas valve installed in the carbon dioxide recovery line, A non-recoverable gas line connected to the aforementioned discharge line, A non-recoverable gas valve is provided in the aforementioned non-recoverable gas line, A control device that closes the recovery gas valve and opens the non-recovered gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure, and closes the non-recovered gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum relative to the recovery pressure, A pretreatment device capable of removing moisture contained in the exhaust gas, Equipped with, The pretreatment device comprises a dehumidifying tower capable of removing moisture contained in the exhaust gas from the blower, and a dry exhaust gas line that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower, to the adsorption tower. The non-recovered gas line has a recycling line connected to the dry exhaust gas line, The non-recovered gas valve has a recycling valve installed in the recycling line, The control device opens the recycle valve when the pressure inside the adsorption tower is lower than the recovery pressure or is assumed to be lower than the recovery pressure, and closes the recycle valve when the pressure inside the adsorption tower is higher than the recovery pressure or is assumed to be higher than the recovery pressure. Carbon dioxide capture equipment.

5. A carbon dioxide recovery system capable of recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption tower is filled with carbon dioxide adsorbent material, which is made of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, A blower that sends the exhaust gas into the adsorption tower, A suction device for vacuum suction inside the adsorption tower, The discharge line connected to the discharge port of the suction device, A carbon dioxide recovery line connected to the aforementioned discharge line, A recovery gas valve installed in the carbon dioxide recovery line, A non-recoverable gas line connected to the aforementioned discharge line, A non-recoverable gas valve is provided in the aforementioned non-recoverable gas line, A control device that closes the recovery gas valve and opens the non-recovered gas valve when the pressure inside the adsorption tower is low vacuum or is assumed to be low vacuum relative to a predetermined recovery pressure, and closes the non-recovered gas valve and opens the recovery gas valve when the pressure inside the adsorption tower is high vacuum or is assumed to be high vacuum relative to the recovery pressure, A pretreatment device capable of removing moisture contained in the exhaust gas, Equipped with, The pretreatment device comprises a dehumidifying tower capable of removing moisture contained in the exhaust gas from the blower, and a dry exhaust gas line that guides the dry exhaust gas, which is the exhaust gas that has passed through the dehumidifying tower, to the adsorption tower. The non-recovered gas line comprises a non-recovered gas discharge line with an open end and a recycling line connected to the dry exhaust gas line. The non-recoverable gas valve comprises a discharge valve provided in the non-recoverable gas discharge line and a recycling valve provided in the recycling line. The control device is If the pressure inside the adsorption tower is a vacuum lower than the recovery pressure and a vacuum lower than the recycling pressure which is closer to atmospheric pressure than the recovery pressure, or if it is assumed to be a vacuum lower than the recycling pressure, the discharge valve is opened and the recycling valve is closed. If the pressure inside the adsorption tower is lower than the recovery pressure and higher than the recycling pressure, or if it is assumed that the pressure is lower than the recovery pressure and higher than the recycling pressure, the discharge valve is closed and the recycling valve is opened. When the pressure inside the adsorption tower is higher than the recovery pressure, or when it is assumed to be a high vacuum, the discharge valve and the recycle valve are closed. Carbon dioxide capture equipment.

6. In a carbon dioxide recovery facility according to any one of claims 1 to 5, The carbon dioxide adsorbent is a zeolite. Carbon dioxide capture equipment.

7. In the carbon dioxide recovery equipment described in Claim 6, The recovery pressure is -75 to -95 kPaG. Carbon dioxide capture equipment.

8. In a carbon dioxide recovery facility according to any one of claims 1 to 7, The carbon dioxide adsorbent is a porous structure in which multiple through-holes are formed that penetrate each other in the same direction. Carbon dioxide capture equipment.

9. A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption step in which exhaust gas is introduced into an adsorption tower, which is filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and the carbon dioxide in the exhaust gas is adsorbed by the carbon dioxide adsorbent, A detachment step involves vacuuming the inside of the adsorption tower to detach the carbon dioxide adsorbed on the carbon dioxide adsorbent from the carbon dioxide adsorbent, Execute, The detachment process includes a carbon dioxide recovery process that guides the gas from the adsorption tower as recovered gas to a recovery gas tank, a non-recovered gas flow process that guides the gas from the adsorption tower as non-recovered gas to a location other than the recovery gas tank, and a control process that controls the execution of the carbon dioxide recovery process and the non-recovered gas flow process. In the control step, the carbon dioxide recovery step is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure, and the non-recovered gas flow step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure. The control process includes a pressure detection step for detecting the pressure inside the adsorption tower, a gas flow control step for executing one of the carbon dioxide recovery step and the non-recovered gas flow step based on the pressure detected in the pressure detection step, and a suction force control step for controlling the suction force for vacuum suction inside the adsorption tower. In the suction force control step, when the pressure detected in the pressure detection step becomes higher than the recovery pressure and closer to the recovery pressure than atmospheric pressure, or the suction force change pressure is the recovery pressure, the suction force is increased. Methods for capturing carbon dioxide.

10. A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption step in which exhaust gas is introduced into an adsorption tower, which is filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and the carbon dioxide in the exhaust gas is adsorbed by the carbon dioxide adsorbent, A detachment step involves vacuuming the inside of the adsorption tower to detach the carbon dioxide adsorbed on the carbon dioxide adsorbent from the carbon dioxide adsorbent, Execute, The detachment process includes a carbon dioxide recovery process that guides the gas from the adsorption tower as recovered gas to a recovery gas tank, a non-recovered gas flow process that guides the gas from the adsorption tower as non-recovered gas to a location other than the recovery gas tank, and a control process that controls the execution of the carbon dioxide recovery process and the non-recovered gas flow process. In the control step, the carbon dioxide recovery step is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure, and the non-recovered gas flow step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure. The control process includes a suction force control process for controlling the suction force that vacuums the inside of the adsorption tower, and a gas flow control process for executing one of the processes of the carbon dioxide recovery process and the non-recovered gas flow process. In the suction force control step, after a predetermined time has elapsed since vacuum suction began inside the adsorption tower, the suction force is increased. In the gas flow control step, the non-recovered gas flow step is executed assuming that the pressure inside the adsorption tower is a lower vacuum than the recovery pressure before increasing the suction force in the suction force control step, and the carbon dioxide recovery step is executed assuming that the pressure inside the adsorption tower is a higher vacuum than the recovery pressure after increasing the suction force in the suction force control step. Methods for capturing carbon dioxide.

11. In the carbon dioxide recovery method according to claim 9 or 10, The non-recovered gas distribution process includes a non-recovered gas release process that releases the non-recovered gas into the atmosphere. In the control step, the unrecovered gas release step is executed when the pressure inside the adsorption tower is at or is assumed to be at a low vacuum relative to the recovery pressure, and the unrecovered gas release step is not executed when the pressure inside the adsorption tower is at or is assumed to be at a high vacuum relative to the recovery pressure. Methods for capturing carbon dioxide.

12. A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption step in which exhaust gas is introduced into an adsorption tower, which is filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and the carbon dioxide in the exhaust gas is adsorbed by the carbon dioxide adsorbent, A detachment step involves vacuuming the inside of the adsorption tower to detach the carbon dioxide adsorbed on the carbon dioxide adsorbent from the carbon dioxide adsorbent, A pretreatment to remove moisture contained in the exhaust gas, Execute, The detachment process includes a carbon dioxide recovery process that guides the gas from the adsorption tower as recovered gas to a recovery gas tank, a non-recovered gas flow process that guides the gas from the adsorption tower as non-recovered gas to a location other than the recovery gas tank, and a control process that controls the execution of the carbon dioxide recovery process and the non-recovered gas flow process. The aforementioned pretreatment includes a dehumidification step of sending the exhaust gas into a dehumidification tower to remove moisture from the exhaust gas, and then guiding the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower, to the adsorption tower. The non-recovered gas distribution process includes a recycling process in which the non-recovered gas is mixed into the dry exhaust gas. In the control step, the carbon dioxide recovery step is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to a predetermined recovery pressure; the unrecovered gas flow step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure; the recycling step is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum with respect to the recovery pressure; and the recycling step is not executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum with respect to the recovery pressure. Methods for capturing carbon dioxide.

13. A carbon dioxide recovery method for recovering carbon dioxide from exhaust gas containing at least nitrogen and carbon dioxide, An adsorption step in which exhaust gas is introduced into an adsorption tower, which is filled with carbon dioxide adsorbent material formed of a carbon dioxide adsorbent that can adsorb carbon dioxide under high pressure and release carbon dioxide under low pressure, and the carbon dioxide in the exhaust gas is adsorbed by the carbon dioxide adsorbent, A detachment step involves vacuuming the inside of the adsorption tower to detach the carbon dioxide adsorbed on the carbon dioxide adsorbent from the carbon dioxide adsorbent, A pretreatment to remove moisture contained in the exhaust gas, Execute, The detachment process includes a carbon dioxide recovery process that guides the gas from the adsorption tower as recovered gas to a recovery gas tank, a non-recovered gas flow process that guides the gas from the adsorption tower as non-recovered gas to a location other than the recovery gas tank, and a control process that controls the execution of the carbon dioxide recovery process and the non-recovered gas flow process. The aforementioned pretreatment includes a dehumidification step of sending the exhaust gas into a dehumidification tower to remove moisture from the exhaust gas, and then guiding the dry exhaust gas, which is the exhaust gas that has passed through the dehumidification tower, to the adsorption tower. The non-recovered gas distribution process includes a non-recovered gas discharge process for releasing the non-recovered gas into the atmosphere, and a recycling process for mixing the non-recovered gas into the dry exhaust gas. In the control process described above, The carbon dioxide recovery process is executed when the pressure inside the adsorption tower is a high vacuum or is assumed to be a high vacuum based on a predetermined recovery pressure, and the non-recovered gas flow process is executed when the pressure inside the adsorption tower is a low vacuum or is assumed to be a low vacuum based on the recovery pressure. If the pressure inside the adsorption tower is lower than the recovery pressure and lower than the recycling pressure, which is closer to atmospheric pressure than the recovery pressure, or if it is assumed that the pressure is lower than the recycling pressure, the non-recovered gas discharge step is executed, and the recycling step is not executed. If the pressure inside the adsorption tower is lower than the recovery pressure and higher than the recycling pressure, or if it is assumed that the pressure is lower than the recovery pressure and higher than the recycling pressure, the non-recovered gas discharge step will not be performed, and the recycling step will be performed instead. If the pressure inside the adsorption tower is a higher vacuum than the recovery pressure, or if it is assumed to be a high vacuum, the non-recovered gas discharge step and the recycling step will not be performed. Methods for capturing carbon dioxide.

14. A carbon dioxide recovery method according to any one of claims 9 to 13, Zeolite is used as the carbon dioxide adsorbent. Methods for capturing carbon dioxide.

15. In the carbon dioxide recovery method according to Claim 14, The recovery pressure is -75 to -95 kPaG. Methods for capturing carbon dioxide.

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