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CN-121993810-A - Carbon capture waste heat recycling system based on double-side direct expansion heat exchange

CN121993810ACN 121993810 ACN121993810 ACN 121993810ACN-121993810-A

Abstract

The application relates to the technical field of carbon dioxide recovery, and discloses a carbon capture waste heat recycling system based on double-side direct expansion heat exchange, which comprises an absorption tower, a desorption tower and a high-temperature heat pump loop; the high-temperature heat pump system comprises an absorption tower, a high-temperature heat pump circuit, a carbon capture system and an energy utilization system, wherein a first heat exchange unit is arranged in the absorption tower and comprises a fin tube type heat exchanger for recovering flue gas waste heat, a second heat exchange unit is arranged in the desorption tower and comprises a spray type heat exchanger for providing heat for rich liquor desorption, a refrigerant channel of the high-temperature heat pump circuit is sequentially connected with the first heat exchange unit and the second heat exchange unit to form an energy utilization system for transferring the flue gas waste heat to the desorption tower, an energy flow path in the carbon capture system is reconstructed, a core pain point of high energy consumption is solved from the source, and multiple beneficial effects of energy conservation, efficiency improvement, cost reduction and simplification are generated.

Inventors

  • LI YANAN
  • HUANG GUOHUA
  • LI SHAOFEI
  • DU WEIWEI
  • ZHAO JINZI
  • SUN WENQIAN
  • GU ZAIFENG

Assignees

  • 同方节能工程技术有限公司
  • 同方智慧能源有限责任公司

Dates

Publication Date
20260508
Application Date
20251126

Claims (10)

  1. 1. The carbon capture waste heat recycling system based on double-side direct expansion heat exchange is characterized by comprising an absorption tower (2), a desorption tower (5) and a high-temperature heat pump loop; a first heat exchange unit (17) is arranged in the absorption tower (2), and the first heat exchange unit (17) comprises a fin-tube type heat exchanger and is used for recovering flue gas waste heat; a second heat exchange unit (18) is arranged in the desorption tower (5), and the second heat exchange unit (18) comprises a spray type heat exchanger and is used for providing heat for desorption of the rich liquid; The refrigerant channel of the high-temperature heat pump loop is sequentially connected with the first heat exchange unit (17) and the second heat exchange unit (18) to form an energy utilization system for transferring the flue gas waste heat to the desorption tower.
  2. 2. The carbon capture waste heat recovery system of claim 1, wherein the fins of the fin tube heat exchanger of the first heat exchange unit (17) are spirally wound on heat exchange tubes, the fin heat exchange tubes being arranged in a tube array.
  3. 3. The carbon capture waste heat recovery system of claim 2, wherein the fins (222) of the fin tube heat exchanger are open cell structures.
  4. 4. The carbon capture waste heat recovery system of claim 1, wherein the spray heat exchanger of the second heat exchange unit (18) comprises a rich liquid spray device and a heat exchange tube bundle through which a refrigerant flows, the rich liquid spray device spraying rich liquid to the outer surface of the heat exchange tube bundle to reduce liquid boundary layer thermal resistance and enhance heat transfer.
  5. 5. The carbon capture waste heat recovery system of claim 1, wherein the high temperature heat pump circuit comprises a compressor (13), a refrigerant passage of the second heat exchange unit (18), a first throttling device and a refrigerant passage of the first heat exchange unit (17) connected in sequence by pipelines, forming a thermodynamic cycle that elevates a low temperature heat source to a high temperature heat source.
  6. 6. The carbon capture waste heat recovery system of claim 5, wherein the high temperature heat pump loop further comprises an economizer (14) and a make-up loop; the economizer (14) is connected in series in a line between the refrigerant outlet of the second heat exchange unit (18) and the first throttling means; the make-up circuit comprises a second throttling device (15) with an inlet connected to the main refrigerant line before the economizer (14) and an outlet connected to the inlet of the make-up channel of the economizer (14), the outlet of the make-up channel being connected to the intermediate make-up port of the compressor (13) to widen the heat pump operating temperature range and improve the system performance.
  7. 7. The carbon capture waste heat recovery system of claim 6, wherein the high temperature heat pump circuit further comprises an efficient engine (12), the Gao Xiaoqi (12) being disposed on a line between a refrigerant outlet of the first heat exchange unit (17) and an inlet of the compressor (13).
  8. 8. The carbon capture waste heat recovery system according to claim 1, further comprising a lean rich liquid heat exchanger (4) having a hot side inlet connected to a lean liquid outlet of the desorption column (5), a hot side outlet connected to a lean liquid inlet of the absorption column (2), a cold side inlet connected to a rich liquid outlet of the absorption column (2), and a cold side outlet connected to a rich liquid inlet of the desorption column (5) for recovering lean liquid heat.
  9. 9. The carbon capture waste heat recovery system according to claim 1, wherein an inter-stage cooler (9) is further provided on the housing of the absorption tower (2), and a cooling flow passage of the inter-stage cooler (9) penetrates through the housing of the absorption tower (2) and is located at a middle position thereof for improving the absorption capacity of the absorption tower.
  10. 10. The carbon capture waste heat recovery system of claim 4, wherein the heat exchange tubes in the second heat exchange unit (18) are supported and fixed by a heat exchange tube support plate (54).

Description

Carbon capture waste heat recycling system based on double-side direct expansion heat exchange Technical Field The invention belongs to the technical field of flue gas carbon dioxide recovery, and particularly relates to a carbon capture waste heat recycling system based on double-side direct expansion heat exchange. Background Carbon dioxide capture, utilization and sequestration technologies have become an indispensable critical path for achieving the goals of "carbon peak" and "carbon neutralization". In the energy structure of China, coal-fired power plants are one of main sources of carbon dioxide emission, and the emission amount of the coal-fired power plants accounts for 40-50% of the total emission amount of the whole country. In this context, it is of great importance to implement efficient and economical carbon capture technologies in power plants. At present, chemical absorption methods represented by an alcohol amine method are widely used because of high technical maturity and stable trapping efficiency. The technology realizes the absorption and separation of carbon dioxide through the reversible chemical reaction of the alcohol amine solution and the carbon dioxide in the flue gas. Although the alcohol amine process has high efficiency and mature advantages in terms of carbon dioxide capture, the process has significant energy consumption bottlenecks. For example, the rich liquid after carbon dioxide absorption needs to be regenerated by heating in a desorber, a process that typically requires the consumption of a large amount of heat energy, typically supplied by an external steam system. This results in high energy consumption for the operation of the carbon capture system, which severely restricts its large-scale commercial application. However, researchers are exploring ways to reduce regeneration energy consumption by improving the alcohol amine solution formulation and introducing catalysts, etc., in an effort to improve overall energy efficiency. At the same time, a great amount of low-temperature waste heat which is not effectively utilized is contained in the flue gas at the front end of the carbon capture system, including the sensible heat of the flue gas and the considerable latent heat of condensation contained in water vapor. In the prior art, an indirect heat exchange mode with circulating water as an intermediate working medium is mostly adopted for recycling the waste heat. The technical route has inherent defects that firstly, the heat transfer temperature difference loss exists due to the addition of an intermediate heat exchange link, the overall heat exchange efficiency is low, secondly, the system needs to be provided with additional heat exchangers, water pumps, water tanks and other equipment, so that the system is complex, the occupied area is large, the initial investment is high, and moreover, the corrosion and dust accumulation of the heat exchange equipment are easily caused by acidic components and dust in the flue gas, so that the stability and the energy efficiency of the long-term operation of the system are influenced. Therefore, there is an urgent need to develop a novel system that can directly and efficiently recover the flue gas waste heat and directly apply the heat to the desorption regeneration process. The direct recovery technology can break through the technical limitation of traditional indirect heat exchange, and obviously reduces the energy consumption in the carbon capture process, thereby promoting the large-scale application of the carbon capture technology. Disclosure of Invention In view of the problems of the prior art, the invention solves the problems of high heat exchange temperature difference, low efficiency and complex system existing in the prior indirect heat exchange technology by efficiently recovering the flue gas waste heat generated in the carbon capture process and directly using the flue gas waste heat in the desorption process to obviously reduce the overall energy consumption of the carbon capture system. The invention provides a carbon capture waste heat recycling system based on double-side direct expansion heat exchange, which comprises an absorption tower, a desorption tower and a high-temperature heat pump loop, wherein a first heat exchange unit is arranged in the absorption tower and comprises a fin tube type heat exchanger for recycling waste heat of flue gas, a second heat exchange unit is arranged in the desorption tower and comprises a spray type heat exchanger for providing heat for desorption of rich liquid, and a refrigerant channel of the high-temperature heat pump loop is sequentially connected with the first heat exchange unit and the second heat exchange unit to form an energy utilization system for transferring the waste heat of the flue gas to the desorption tower. Optionally, the fins of the fin tube heat exchanger of the first heat exchange unit are spirally wound on heat exchange tubes, and the fin h