Method, system and apparatus for flue gas cooling

Abstract

Disclosed herein are apparatus, systems, and methods for flue gas cooling for a carbon capture process. The flue gas cooling process for carbon capture includes cooling flue gas in a direct contact cooler with cooling water cooled in a closed cooling loop, cooling circulating water in the closed cooling loop utilizing an air-cooled heat exchanger, cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue stream to the water dew point, storing the excess water in an excess water storage vessel, and directing the excess water stored in the excess water storage vessel to the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue stream to the water dew point.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Application No. 63 / 392,391, filed July 26, 2022, which is incorporated herein by reference in its entirety.

[0002] In post-combustion carbon capture (PCC) facilities, carbon dioxide (CO2) is separated from flue gases via an absorption medium. The CO2 absorber towers in these units typically operate at temperatures ranging from 100°F to 130°F to allow effective absorption and prevent accelerated degradation of the absorption medium exposed to oxygen and other contaminants in the flue gases.

[0003] CO2-containing flue gas streams from various industrial processes achieve post-combustion temperatures ranging from 150°F to 1500°F. These streams must be cooled before contacting the absorption media in a CO2 absorber. Flue gas streams are typically cooled using a combination of heat recovery for either power generation or cogeneration, followed by a direct contact cooling process utilizing a cooling water loop. Cooling water systems can be expensive and can require significant amounts of fresh water make-up, placing a large demand on utilities and local fresh water sources.

[0004] 1 shows a prior art cooling process for a post-combustion flue gas stream 101 using heat recovery 100 for power generation or cogeneration, followed by a fresh water cooling loop that is cooled using a direct contact cooler process 120 and an evaporative cooling process 150. The evaporative cooling water process 150 can be expensive and typically requires large amounts of fresh water make-up 153, which can place a large demand on local utilities and fresh water sources.

[0005] Combustion flue gas 101 from various combustion processes can achieve post-combustion temperatures ranging from 150°F to 1500°F. Flue gas is primarily composed of a mixture of nitrogen, oxygen, carbon dioxide, and water. Flue gas contains SO 2 , which are common terms for sulfur oxides and nitrogen oxides, respectively. x and NO x The presence and levels of additional contaminants in the flue gas (e.g., sulfur, chlorine, bromine, etc.) can depend on the relative levels of those contaminants in the fuel source. The flue gas may also include particulate matter.

[0006] The heat recovery process 100 is typically utilized for power generation or process heating requirements. The heat recovery process 100 typically reduces the flue gas temperature to a range of 300°F to 150°F.

[0007] The direct contact cooler (DCC) 120 utilizes a quench process in which quench water is mixed directly into the flue gas stream to provide rapid heat transfer. The hot quench water from the bottom of the DCC is cooled by an external cooling loop, typically in the form of a freshwater cooling loop 150 with evaporative cooling. The cooled quench water is then circulated back to the top of the DCC.

[0008] The cooling water is utilized to cool the quench water used in the DCC 120, typically via a liquid-liquid exchanger or quench water cooler 140. The heated cooling water 152 from this heat exchanger 140 is sent to an evaporative cooling process 150 where a portion of the water is evaporated. The evaporative process allows the cooling water to cool to near the wet-bulb temperature of the ambient air, and the cooled water 151 is pumped back to cool the quench water. Additional cooling water is rejected from the evaporative cooling process 150 as blowdown water 154. The rate of blowdown is used to control the concentration of contaminants in the cooling water system.

[0009] The evaporative cooling process 150 is provided with fresh water make-up 153 to replenish water losses due to evaporation and blowdown. Fresh water make-up requirements may be cost-prohibitive or unavailable based on the local availability of fresh water. Summary of the Invention

[0010] PCC facilities often require the flue gas stream to be cooled to meet the process temperature requirements of the selected CO2 absorption technology. The standard cooling process in PCC facilities involves the use of a direct contact cooler (DCC). In a DCC, hot flue gas is directly contacted with quench water in a countercurrent configuration, allowing the flue gas to be cooled to the desired temperature. The cooled flue gas stream exiting the DCC may be saturated with water. The quench water may be warmed as it removes heat from the flue gas in the DCC. The warmed quench water typically exchanges heat with a separate cooling water loop, which rejects heat via evaporative cooling.

[0011] PCC facilities with limited water resources may utilize air-cooled heat exchangers (ACHEs) instead of evaporative cooling technologies (e.g., cooling towers) to cool the quench water for DCC. In processes with stable quench water conditions (i.e., consistent flow and temperature), the available cooling duty of the quench water ACHE is limited by the ambient temperature (T a ) The available cooling duty of the quench water ACHE may be higher when the ambient temperature is lower, and the available cooling duty of the quench water ACHE may be lower when the ambient temperature is higher. Variations in quench water ACHE cooling duty are typically managed by adjusting other process parameters (e.g., adjusting the flow through the ACHE by implementing a bypass line with temperature control).

[0012] All post-combustion flue gas streams contain water. The water present in the flue gas stream can be both a product of combustion and / or a component of the combustion air. The temperature at which water condenses from the flue gas is called the water dew point temperature (T s ) T s is primarily a function of the relative amount of water in the flue stream.s is higher for streams with more water and lower for streams with less water.

[0013] To maintain the amount of liquid water in the DCC, the flue gas flow is adjusted to T s The flue gas can be cooled to T s If the flue gas is cooled below T, water may condense and accumulate in the DCC. s If the quench water is cooled to temperatures above 1000°C, some of the quench water may evaporate and saturate the flue gas stream. In the latter case, water must be continuously supplied to offset the evaporation losses and maintain the liquid level in the DCC. In some instances, it may be necessary to blow down quench water from the DCC to offset the buildup of impurities in the quench water.

[0014] The cooling process can be optimized to utilize higher available ACHE duty during sustained low ambient temperatures (e.g., nighttime) to offset lower available ACHE duty during sustained high ambient temperatures (e.g., daytime). When higher ACHE duty is available, the flue gas is cooled to T s The water can be condensed by cooling to a temperature below 1000 K. The condensed water can be stored and used as makeup water to the DCC when lower ACHE duty is available due to high ambient temperatures.

[0015] Using a higher ACHE cooling duty to condense and store condensate beneficially minimizes or eliminates the need for external makeup water to the DCC. Furthermore, instead of increasing the surface area of the ACHE to cover a wider range of ambient conditions, storing and reusing condensate may mitigate the effects of warm periods and allow the ACHE to be designed for a narrower band of ambient conditions. The stored condensate can also be beneficially used to minimize or eliminate external makeup water requirements for other water consumers within the PCC or for external users.

[0016] In a first aspect, which in light of the disclosure set forth herein is not intended to limit the disclosure in any way but may be combined with any other aspect or portion thereof described herein, a flue gas cooling process includes cooling flue gas in a direct contact cooler using circulating water cooled in a closed cooling loop; cooling the circulating water in the closed cooling loop utilizing an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue stream to the water dew point; storing the excess water in an excess water storage vessel; and utilizing the excess water stored in the excess water storage vessel in the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue stream to the water dew point.

[0017] In a second aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise specified, the flue gas cooling process further includes directing a further portion of the excess water in the carbon capture process to a user.

[0018] In a third aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise specified, the flue gas cooling process further comprises directing a further portion of the excess water to at least one external water consumer.

[0019] In a fourth aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise specified, the flue gas cooling process further includes receiving an external water supply via an excess water storage vessel.

[0020] In a fifth aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise specified, the flue gas cooling process further includes cooling the cooled circulating water in a closed cooling loop by a chilling unit to increase the amount of excess water produced.

[0021] In a sixth embodiment, which may be combined with any other embodiment or portion thereof described herein unless otherwise specified, the excess water storage vessel is part of a direct contact cooler.

[0022] In a seventh embodiment, which may be combined with any other embodiment or portion thereof described herein unless otherwise specified, the excess water storage vessel is external to the direct contact cooler.

[0023] In an eighth aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise stated, a flue gas cooling process includes: cooling flue gas in a direct contact cooler using circulating water cooled in a closed cooling loop; cooling the circulating water in the closed cooling loop utilizing an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue stream to the water dew point; storing the excess water in an excess water storage vessel; and directing the excess water stored in the excess water storage vessel to a user in a carbon capture facility.

[0024] In a ninth aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise stated, the flue gas cooling process further includes directing a portion of the excess water stored in the excess water storage vessel to the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue stream to the water dew point.

[0025] In a tenth aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise stated, a flue gas cooling process includes: cooling flue gas in a direct contact cooler using circulating water cooled in a closed cooling loop; cooling the circulating water in the closed cooling loop utilizing an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue stream to the water dew point; storing the excess water in an excess water storage vessel; and directing the excess water to at least one water consumer external to the carbon capture facility.

[0026] In an eleventh aspect, which may be combined with any other aspect or portion thereof described herein unless otherwise stated, a flue gas cooling process includes: cooling flue gas in a direct contact cooler using circulating water cooled in a closed cooling loop, wherein the cooling of the flue gas produces excess water; and cooling the circulating water in the closed cooling loop using an air-cooled heat exchanger.

[0027] In a twelfth aspect, any of the features, functions, and alternatives described in connection with one of Figures 2 or 3 may be combined with any of the features, functions, and alternatives described in connection with the other of Figures 2 or 3.

[0028] Additional features and advantages of the disclosed devices, systems, and methods will be described in, and will be apparent from, the following detailed description and drawings. The features and advantages described herein are not all-inclusive, and in particular, many additional features and advantages will be apparent to those skilled in the art in view of the drawings and description. Also, any particular embodiment need not possess all of the advantages enumerated herein. Furthermore, it should be noted that the language used herein has been chosen primarily for readability and descriptive purposes, and not to limit the scope of the inventive subject matter. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram illustrating a prior art flue gas cooling process for CO2 capture.

[0030] [Figure 2] FIG. 2 is a diagram illustrating a flue gas cooling process including process optimization according to one embodiment of the present disclosure.

[0031] [Figure 3] FIG. 3 illustrates a further embodiment of a flue gas cooling process including process optimization according to another aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0032] The detailed description should be construed as illustrative only and does not describe every possible embodiment, which would be impractical, if not impossible. Those skilled in the art will be able to implement numerous alternative embodiments that would still fall within the scope of the claims. To the extent that any term is referred to in a manner consistent with a single meaning, this is done for clarity and illustration only and is not intended to limit such claim term to that single meaning.

[0033] The present disclosure provides novel processes, apparatus, and systems that can be used individually or in combination to optimize utility costs associated with cooling post-combustion flue gases. While the embodiments shown in Figures 2 and 3 and described herein are directed to flue gas cooling processes used in carbon capture facilities, the cooling processes described herein may be used to cool any condensable components in the cooled gas stream of any type of facility, including, but not limited to, carbon capture facilities.

[0034] In some non-limiting embodiments, as shown in Figures 2 and 3, a quench water cooler 230 using closed-loop air cooling may utilize an air-cooled heat exchanger (ACHE) 230 that may use ambient air to cool the quench water, which may then return to the direct contact cooler (DCC) 220. The DCC 220 shown in Figures 2 and 3 may function similarly to the DCC 120. Post-combustion flue gas 201 is typically about 7-20% water by volume, and condensation occurs when the combustion flue gas 201 is cooled below its water dew point. The non-limiting embodiments shown in Figures 2 and 3 do not adversely affect the performance of the absorber (not shown).

[0035] The quench water cooler 230 may have a higher available cooling duty when the ambient temperature is low (e.g., at night). The quench water cooler may have a higher available cooling duty when the ambient temperature is high (e.g., during the day). Advantageously, the higher available cooling duty of the quench water cooler 230 may be utilized to cool the flue gas below its dew point and condense water from the flue gas stream, resulting in a surplus of water 221 in the DCC 220. The surplus water 221 in the DCC 220 may be stored in an excess water storage vessel 240. In the embodiment shown in FIG. 2, the surplus water storage vessel 240 is contained within and / or is part of the DCC 220. In other embodiments, such as the embodiment of FIG. 3, the surplus water storage vessel 240 is separate from an additional storage volume in the DCC 220 to which a portion of the surplus water 221 may be directed.

[0036] To offset water losses within the DCC 220, all or a portion of the water from 240 can be sent to the DCC 220 as quench water make-up water 222. Water loss in the DCC 220 can occur if the lower available cooling duty of the quench water cooler 230 is insufficient to cool the flue gas to its water dew point. Water can evaporate within the DCC 220 and saturate the flue gas. One advantage is that the quench water make-up 222 allows evaporation within the DCC 220 while maintaining the amount of quench water in the system. A second advantage is that allowing evaporation in the DCC 220 provides evaporative cooling (latent heat transfer) in the DCC 220, reducing the required cooling duty of the quench water cooler 230. The combination of evaporative cooling in the DCC 220 and cooling in the quench water cooler 230 can expand the range of ambient temperatures that can provide sufficient cooling to the flue gas to meet downstream process requirements without requiring external water make-up.

[0037] If external water is available, auxiliary water make-up 290 can be any source of make-up water 222. Additionally or optionally, excess water 221 in excess water storage vessel 240, or a portion thereof, can be sent to other users within the carbon capture facility or to water users external to carbon capture facility 280.

[0038] In processes where the flue gas stream must be cooled to a temperature lower than can practically be achieved by the air cooling process, an optional chilling unit 270 can be added downstream of the quench water cooler 230 to chill the quench water 271 from the quench water cooler 230. After the quench water has been chilled to a lower temperature than the quench water exiting the quench water cooler 230, it is supplied as chilled quench water 272 to the direct contact cooler 220 where it is used to quench the flue gas. The chiller 270 can provide additional cooling duty and thus generate an increased amount of excess water 221, which can then be used for other carbon capture or external users 280.

[0039] As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "an ingredient" or "the ingredient" means "at least one ingredient," and includes two or more ingredients.

[0040] The terms "comprise," "comprises," and "comprising" should be interpreted inclusively rather than exclusively. Similarly, the terms "include," "including," and "or" should all be interpreted inclusively unless such construction is clearly prohibited by context. Nevertheless, the compositions disclosed herein may lack elements not specifically disclosed herein. Accordingly, disclosure of an embodiment using the term "comprising" includes disclosure of embodiments "consisting essentially of" and "consisting of" the specified components. A composition "consisting essentially of" contains at least 75% by weight of the referenced component, preferably at least 85% by weight of the referenced component, more preferably at least 95% by weight of the referenced component, and most preferably at least 98% by weight of the referenced component.

[0041] The terms "at least one" and "and / or" used in the context of "at least one of X or Y" and "X and / or Y", respectively, should be interpreted as "X" or "Y" or "X and Y". For example, "at least one of honey or chicory root syrup" should be interpreted as "honey without chicory root syrup" or "chicory root syrup without honey" or "both honey and chicory root syrup".

[0042] As used herein, the terms "example" and "etc.", particularly when followed by a list of terms, are merely exemplary and descriptive and should not be considered exclusive or comprehensive. The many features and advantages of the present disclosure are apparent from the written description, and thus, the appended claims are intended to cover all such features and advantages of the present disclosure. Moreover, since numerous modifications and changes will readily occur to those skilled in the art, the present disclosure is not limited to the exact construction and operation as shown and described. Therefore, the described embodiments should be construed as illustrative rather than restrictive, and the present disclosure should not be limited to the details given herein, but should be defined by the full scope of the following claims and their equivalents, whether foreseeable or unforeseeable in the future.

Claims

1. 1. A flue gas cooling process comprising: cooling the flue gas in a direct contact cooler using cooled circulating water in a closed cooling loop; cooling the circulating water in the closed cooling loop using an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue gas to the water dew point; storing the excess water in an excess water storage container; utilizing the stored excess water in the excess water storage vessel in the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue stream to the water dew point; A flue gas cooling process, including

2. The flue gas cooling process of claim 1 , further comprising the step of directing a further portion of the excess water to a user in a carbon capture process.

3. The flue gas cooling process of claim 1 , further comprising the step of directing a further portion of the excess water to at least one external water consumer.

4. The flue gas cooling process of claim 1 , further comprising receiving an external water supply with the excess water storage vessel.

5. 2. The flue gas cooling process of claim 1, further comprising the step of cooling the circulating water cooled in the closed cooling loop with a chilling unit to increase the amount of excess water produced.

6. 2. The flue gas cooling process of claim 1, wherein the excess water storage vessel is part of the direct contact cooler.

7. The flue gas cooling process of claim 1 , wherein the excess water storage vessel is external to the direct contact cooler.

8. 1. A flue gas cooling process comprising: cooling the flue gas in a direct contact cooler using cooled circulating water in a closed cooling loop; cooling the circulating water in the closed cooling loop using an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue gas to the water dew point; storing the excess water in an excess water storage container; directing the excess water stored in the excess water storage vessel to a user within a carbon capture facility; A flue gas cooling process, including

9. 9. The flue gas cooling process of claim 8, further comprising the step of directing a portion of the excess water stored in the excess water storage vessel to the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue gas to the water dew point.

10. The flue gas cooling process of claim 8 , further comprising the step of directing a portion of the excess water to at least one external water consumer.

11. The flue gas cooling process of claim 8 , further comprising receiving an external water supply with the excess water storage vessel.

12. 9. The flue gas cooling process of claim 8, wherein the excess water storage vessel is part of the direct contact cooler.

13. 9. The flue gas cooling process of claim 8, wherein the excess water storage vessel is external to the direct contact cooler.

14. 9. The flue gas cooling process of claim 8, further comprising the step of cooling the circulating water cooled in the closed cooling loop with a chilling unit to increase the amount of excess water produced.

15. 1. A flue gas cooling process comprising: cooling the flue gas in a direct contact cooler using cooled circulating water in a closed cooling loop; cooling the circulating water in the closed cooling loop using an air-cooled heat exchanger; cooling the flue gas below the water dew point to produce excess water when the available cooling duty of the closed cooling loop exceeds the cooling duty required to cool the flue gas to the water dew point; storing the excess water in an excess water storage container; directing the excess water to at least one water consumer external to the carbon capture facility; A flue gas cooling process, including

16. 16. The flue gas cooling process of claim 15, further comprising directing a portion of the excess water stored in the excess water storage vessel to a user within a carbon capture facility.

17. 16. The flue gas cooling process of claim 15, further comprising: directing a portion of the excess water stored in the excess water storage vessel to the direct contact cooler when the available cooling duty of the closed cooling loop is less than the cooling duty required to cool the flue gas to the water dew point.

18. The flue gas cooling process of claim 15 further comprising receiving an external water supply with the excess water storage vessel.

19. 16. The flue gas cooling process of claim 15, further comprising the step of cooling the circulating water cooled in the closed cooling loop with a chilling unit to increase the amount of excess water produced.

20. 16. The flue gas cooling process of claim 15, wherein the excess water storage vessel is part of the direct contact cooler.

21. 16. The flue gas cooling process of claim 15, wherein the excess water storage vessel is external to the direct contact cooler.

22. 1. A flue gas cooling process comprising: cooling the flue gas in a direct contact cooler using cooled circulating water in a closed cooling loop; Including, cooling the flue gas to produce excess water; Furthermore, the Endo gas cooling process: cooling the circulating water in the closed cooling loop using an air-cooled heat exchanger; A flue gas cooling process, including

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