Facility and method for recovering carbon dioxide

Abstract

To provide a facility and a method for recovering carbon dioxide which can efficiently recover carbon dioxide discharged from an air separation facility.SOLUTION: A recovery facility of carbon dioxide includes: an adsorption device which causes an adsorbent to adsorb impurities containing carbon dioxide from raw material air compressed by an air compressor; a rectification device which rectifies the raw material air from which the impurities has been removed to separate the raw material air into nitrogen and other gases; and a recovery device which is supplied with carbon dioxide removed by the adsorption device with nitrogen separated by the rectification device to recover carbon dioxide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon dioxide capture system and a capture method. [Background technology]

[0002] Conventionally, in cryogenic air separation equipment, carbon dioxide adsorbed in the pretreatment equipment (MS adsorber) was released into the atmosphere together with nitrogen, which is the regeneration gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-196873 A Summary of the Invention [Problem to be solved by the invention]

[0004] Carbon dioxide is a type of greenhouse gas, and in order to achieve carbon neutrality, it is desirable to capture carbon dioxide rather than releasing it into the atmosphere. In order to solve this problem, it is possible to use a method of capturing carbon dioxide by compressing the atmosphere and supplying it to a carbon dioxide capture device. However, since the concentration of carbon dioxide in the atmosphere is low, it is difficult to capture carbon dioxide efficiently using this method.

[0005] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a carbon dioxide recovery system and a recovery method capable of efficiently recovering carbon dioxide released from an air separation system. [Means for solving the problem]

[0006] The carbon dioxide recovery equipment of the present invention comprises an adsorption device that removes impurities including carbon dioxide from raw air compressed by an air compressor by adsorbing them onto an adsorbent, a rectification device that rectifies the raw air from which the impurities have been removed and separates it into nitrogen and other gases, and a recovery device that recovers carbon dioxide by supplying the carbon dioxide removed by the adsorption device together with the nitrogen separated in the rectification device.

[0007] The carbon dioxide removed by the adsorption device and the nitrogen supplied from the rectification device may be supplied to the recovery device via an air compressor different from the air compressor.

[0008] The recovery device may be supplied with raw air compressed by an air compressor other than the air compressor.

[0009] The carbon dioxide recovery method of the present invention includes an adsorption step of removing impurities including carbon dioxide from raw air compressed by an air compressor by adsorbing them onto an adsorbent, a rectification step of rectifying the raw air from which the impurities have been removed and separating it into nitrogen and other gases, and a recovery step of supplying the carbon dioxide removed in the adsorption step together with the nitrogen separated in the rectification step to a recovery device to recover carbon dioxide.

[0010] The recovery step may include a step of supplying the carbon dioxide removed in the adsorption step and the nitrogen separated in the rectification step to the recovery device via an air compressor different from the air compressor.

[0011] The recovering step may include a step of supplying raw air compressed by an air compressor other than the air compressor to the recovering device. Effect of the Invention

[0012] According to the carbon dioxide recovery system and recovery method of the present invention, carbon dioxide released from an air separation system can be efficiently recovered. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing the configuration of an air separation plant to which a carbon dioxide recovery facility according to one embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the configuration of a carbon dioxide recovery facility according to one embodiment of the present invention will be described with reference to the drawings.

[0015] Fig. 1 is a block diagram showing the configuration of an air separation plant to which a carbon dioxide recovery system according to one embodiment of the present invention is applied. As shown in Fig. 1, an air separation plant 1 to which a carbon dioxide recovery system according to one embodiment of the present invention is applied includes an air compressor 10, an MS adsorber 11, and a rectification tower 12.

[0016] The air compressor 10 compresses the air taken in through a filter, cools the air using a cooler such as an aftercooler (not shown), and then supplies the cooled air to the MS adsorber 11 as raw air.

[0017] The MS adsorber 11 purifies the feed air supplied from the air compressor 10 by supplying it to the adsorption towers 11b1 and 11b2 via the path 11a. In the adsorption towers 11b1 and 11b2, impurities such as water, hydrocarbons, and carbon dioxide in the passing feed air are adsorbed by an adsorbent and removed. The purified feed air is cooled to near the dew point in a heat exchanger (not shown) provided on the outlet side of the MS adsorber 11, and then supplied to the fractionator 12 via the path 11c.

[0018] In this embodiment, the adsorption towers 11b1 and 11b2 are alternately used. Specifically, while one adsorption tower is used to adsorb and remove impurities, the other adsorption tower is regenerated. In this regeneration process, a regeneration gas, which will be described later, is supplied to the target adsorption tower to regenerate the used adsorbent. By alternately using the adsorption towers 11b1 and 11b2 in this manner, the raw air can be continuously purified. Three or more adsorption towers may be installed and alternately used.

[0019] The rectification tower 12 cools (deep-cools) the feed air supplied from the MS adsorber 11 to near the dew point, and rectifies and separates the feed air into nitrogen, oxygen, and argon by utilizing the difference in liquefaction temperature. The oxygen (product oxygen) and nitrogen (product nitrogen) separated in the rectification tower 12 are supplied to the plant where they will be used, for example, plants that use blast furnaces and converters in the case of oxygen, via the respective product gas delivery routes.

[0020] In this embodiment, the rectification tower 12 includes an upper tower 12a, a main condenser 12b, and a lower tower 12c. The raw air cooled to near the dew point is introduced into the bottom of the lower tower 12c. The lower tower 12c rectifies the introduced raw air and separates it into nitrogen and oxygen-rich liquefied air (hereinafter referred to as oxygen-enriched liquefied air). The nitrogen accumulates at the top of the lower tower 12c, and the oxygen-enriched liquefied air accumulates at the bottom of the lower tower 12c. The nitrogen is condensed in the main condenser 12b to become liquefied nitrogen, and a portion of the liquefied nitrogen is introduced as a reflux liquid into the upper stage of the upper tower 12a through a piping or the like (not shown). A portion of the oxygen-enriched liquefied air at the bottom of the lower tower 12c is introduced in a gas-liquid mixed state into the middle stage of the upper tower 12a through a piping tower (not shown).

[0021] In the upper tower 12a, rectification is performed by the downward and upward movement of the introduced liquefied nitrogen and oxygen-enriched liquefied air, and oxygen and nitrogen are separated. Nitrogen (product nitrogen) accumulates at the top of the upper tower 12a, and oxygen (product oxygen) accumulates at the bottom of the upper tower 12a. Nitrogen is sent to a heat exchanger through a nitrogen extraction pipe (not shown) installed at the top of the upper tower 12a, and is heated to room temperature. Oxygen is sent to a heat exchanger through an oxygen extraction pipe (not shown) installed at the bottom of the upper tower 12a, and is heated to room temperature. The product nitrogen and product oxygen after this heat exchange are supplied to the factories in the steelworks that use them through each product gas supply route. The purity of the nitrogen gas accumulated in the upper tower 12a is higher as it approaches the top of the upper tower 12a. Therefore, nitrogen (waste nitrogen) having a lower purity than the product nitrogen is extracted as regeneration gas below the nitrogen extraction pipe of the upper tower 12a and supplied through regeneration gas supply lines 14, 14a, 14b for use in the regeneration treatment of the MS adsorber 11.

[0022] The regenerated gas is supplied to the adsorption towers performing the regeneration process via the regenerated gas supply paths 14, 14a, and 14b, and the carbon dioxide and moisture adsorbed by the used adsorbent are removed. In the example shown in FIG. 1, the regenerated gas is supplied to the adsorption tower 11b1 via the regenerated gas supply paths 14 and 14a, and the regeneration process is performed to remove the carbon dioxide and moisture adsorbed by the used adsorbent. At the timing when the adsorption towers 11b1 and 11b2 are alternately switched, the regenerated gas supply paths 14a and 14b may also be alternately switched to supply and stop the regenerated gas. The regenerated gas supply paths 14a and 14b may be switched, for example, by adjusting the opening of the three-way valve 14c.

[0023] The regeneration gas containing carbon dioxide produced by the regeneration process is supplied to a carbon dioxide capture facility 2 via a regeneration gas introduction path 15. The carbon dioxide capture facility 2 includes an air compressor 20 and a capture device 21. The air compressor 20 compresses air taken in through a filter and supplies it to the capture device 21. The capture device 21 separates carbon dioxide from the air supplied from the air compressor 20 and the regeneration gas supplied from the regeneration gas introduction path 15, and supplies the separated carbon dioxide to a storage facility.

[0024] In this embodiment, an air compressor 15a is disposed in the regeneration gas introduction path 15 in order to efficiently capture carbon dioxide. In addition, in this embodiment, regeneration gas containing carbon dioxide at any ratio can be introduced into the suction side of the air compressor 20 of the carbon dioxide capture equipment 2. If the target carbon dioxide capture rate of the capture device 21 can be achieved by the regeneration gas alone, the operation of the air compressor 20 may be stopped. This allows the power of the carbon dioxide capture equipment 2 to be reduced. In addition, the ratio of air introduced into the air compressor 20 may be adjusted according to the actual carbon dioxide capture rate of the capture device 21.

[0025] As is clear from the above description, air separation plant 1 to which carbon dioxide recovery equipment according to one embodiment of the present invention is applied is equipped with regeneration gas supply paths 14, 14a, 14b that supply a portion of the nitrogen gas discharged from air separation plant 2 as regeneration gas to adsorption tower 11, and regeneration gas introduction path 15 that introduces the regeneration gas containing carbon dioxide generated by regeneration of adsorption tower 11 into carbon dioxide recovery plant 2. This makes it possible to efficiently recover carbon dioxide released from air separation plant 2.

[0026] [Example] When compressed air is supplied to a carbon dioxide capture facility, 1 Nm of air 3 The air compression unit is 100,000kwh / Nm3. 3 In contrast, when the present invention is applied and a regeneration gas with a carbon dioxide concentration of 0.2% is supplied to a carbon dioxide recovery facility, the power required for carbon dioxide recovery is 100,000 kWh. 3 The power required to recover the same amount of carbon dioxide was 20,000 kWh. This confirmed that the present invention can recover carbon dioxide efficiently.

[0027] Although an embodiment to which the invention made by the present inventors is applied has been described above, the present invention is not limited to the description and drawings which form part of the disclosure of the present invention according to this embodiment. For example, a control device such as a computer may be provided in the air separation facility 1 shown in Fig. 1, and the amount of carbon dioxide supplied to the carbon dioxide recovery facility 2 may be controlled by monitoring the amount of carbon dioxide recovered using the control device. In this way, all other embodiments, examples, operation techniques, etc. made by those skilled in the art based on this embodiment are included in the scope of the present invention. [Explanation of symbols]

[0028] 1. Air separation equipment 2. Carbon dioxide capture equipment 10,15a,20 Air compressor 11 MS adsorber Routes 11a and 11c 11b1,11b2 Adsorption tower 12 Rectification tower 12a Upper tower 12b Main condenser 12c lower tower 14, 14a, 14b Regeneration gas supply route 14c Three-way valve 15 Regenerative gas introduction route 21 Recovery device

Claims

1. an adsorption device that removes impurities including carbon dioxide from the raw air compressed by the air compressor by adsorbing them onto an adsorbent; a rectification device that rectifies the raw air from which the impurities have been removed and separates it into nitrogen and other gases; a recovery unit to which the carbon dioxide removed by the adsorption unit is supplied together with the nitrogen separated in the rectification unit to recover the carbon dioxide; A carbon dioxide capture facility equipped with

2. The carbon dioxide recovery system according to claim 1, wherein the carbon dioxide removed by the adsorption device and the nitrogen supplied from the rectification device are supplied to the recovery device via another air compressor different from the air compressor.

3. 3. The carbon dioxide recovery facility according to claim 1, wherein the recovery device is supplied with raw air compressed by an air compressor other than the air compressor.

4. an adsorption step of removing impurities including carbon dioxide from the raw air compressed by the air compressor by adsorbing the impurities onto an adsorbent; a rectification step of rectifying the raw air from which the impurities have been removed to separate it into nitrogen and other gases; a recovery step of supplying the carbon dioxide removed in the adsorption step together with the nitrogen separated in the rectification step to a recovery device to recover carbon dioxide; A method for capturing carbon dioxide, comprising:

5. The carbon dioxide recovery method according to claim 4, wherein the recovery step includes a step of supplying the carbon dioxide removed in the adsorption step and the nitrogen separated in the rectification step to the recovery device via an air compressor different from the air compressor.

6. 6. The method for recovering carbon dioxide according to claim 4 or 5, wherein the recovery step includes a step of supplying raw air compressed by an air compressor other than the air compressor to the recovery device.

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