Heat pump assisted low-temperature falling film regeneration carbon capture system and operation method thereof

Abstract

The invention discloses a heat pump assisted low-temperature falling film regeneration carbon capture system and an operation method thereof, and belongs to the field of absorption carbon capture and waste heat utilization. The system comprises an absorption carbon capture unit, a heat pump unit, a flue gas flow channel, a condenser cooling water circulation flow channel and a hot water supply circulation flow channel, the absorbed carbon capturing unit is used for capturing CO2 in the flue gas and heating rich liquid in the falling film desorption tower by utilizing circulating hot water, so that the falling film regeneration under the low-temperature condition is realized. The heat pump unit absorbs high-temperature and low-temperature waste heat of flue gas and low-temperature waste heat of cooling water of the condenser, outputs medium-temperature waste heat to the hot water supply circulation flow channel and provides a heat source for the falling film regeneration process. Flue gas recovered by the heat pump and waste heat of cooling water of the condenser are used for driving circulating hot water to heat, low-temperature efficient regeneration of rich liquid is achieved, energy consumption of a carbon capture system is reduced, and the overall energy efficiency of a power plant is improved.

Description

Technical Field

[0001] This invention belongs to the field of carbon capture and waste heat utilization, specifically relating to a carbon capture system with heat pump-assisted low-temperature falling film regeneration and its operation method. Background Technology

[0002] Fossil fuels still dominate the current global energy mix, and the large amounts of carbon dioxide produced during their combustion are a major contributor to climate change. Post-combustion carbon capture technologies, particularly chemical absorption, are considered a key pathway to achieving deep emission reductions in existing coal-fired power plants due to their high technological maturity and adaptability. However, the main bottleneck of this technology lies in its high regeneration energy consumption. Traditional amine-based absorbents typically require regeneration temperatures maintained at 120-140°C. This process necessitates the extraction of large quantities of high-grade steam from the turbine, leading to a significant decrease in power plant efficiency, often exceeding 7 percentage points, which severely restricts the large-scale commercial application of this technology.

[0003] To reduce energy consumption in carbon capture processes, researchers are exploring two main directions: developing novel absorbents and recovering waste heat from power plants. In the development of new absorbents, breakthroughs have been made in low-temperature regeneration absorbents. These novel absorbents, under the action of a catalyst, can reduce the regeneration temperature to below 100°C, fundamentally reducing the requirement for high-grade heat sources. However, how to economically and efficiently provide heat in this temperature range remains an engineering problem to be solved. Regarding waste heat utilization, coal-fired power plants themselves possess abundant low-grade heat sources. On the one hand, the flue gas emitted by boilers contains continuous heat ranging from high to low temperatures; on the other hand, the condenser at the end of the steam turbine continuously discharges large amounts of hot water at 40-50°C, much of which is currently lost directly through cooling towers and not effectively utilized. Although the idea of ​​using heat pump technology to improve the quality of these waste heat sources has been proposed, existing technologies have significant limitations when coupled with carbon capture systems: compression heat pumps, while providing the required heat temperature, suffer from poor economic efficiency due to their high power consumption; heating absorption heat pumps, while having lower power consumption, have low COP and limited output temperature, making it difficult to stably meet regeneration requirements; and traditional incremental absorption heat pumps cannot achieve the high-temperature regeneration requirements of traditional absorbents. Therefore, the application of heat pumps combined with carbon capture systems in coal-fired power plants urgently needs further exploration and development. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the prior art, solve the problems of high regeneration energy consumption and power plant efficiency decline caused by reliance on high-grade steam in traditional carbon capture systems, and provide a carbon capture system with heat pump-assisted low-temperature falling film regeneration and its operation method.

[0005] The specific technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a carbon capture system with heat pump assisted low-temperature falling film regeneration, including a carbon capture unit, a heat pump unit, a flue gas flow channel, a condenser cooling water circulation channel, and a hot water supply circulation channel; The carbon capture unit is used to receive heat from the heat pump unit and absorb and enrich carbon dioxide in the flue gas in the flue gas duct. The heat pump unit is used to absorb the high-temperature and low-temperature waste heat of the flue gas in the flue gas duct, as well as the low-temperature waste heat of the cooling water in the condenser cooling water circulation duct, and release heat to the hot water supply circulation duct at the absorber and condenser. The hot water in the hot water supply circulation duct is used to absorb the heat output by the heat pump unit and enters the jacket layer of the falling film desorption tower to exchange heat with the rich liquid in the falling film tube. The flue gas duct is used to sequentially heat the generator and evaporator with the high-temperature flue gas before it is introduced into the flue gas inlet at the bottom of the absorption tower.

[0006] Preferably, the carbon capture unit includes an absorption tower, a lean liquid cooler, a rich liquid pump, a lean and rich liquid heat exchanger, a falling film desorption tower, a product gas induced draft fan, a product gas condenser, and a lean liquid pump. The flue gas emission outlet at the top of the absorption tower is connected to the flue gas emission channel. The rich liquid outlet at the bottom is connected to the cold-side fluid channel inlet of the rich-lean liquid heat exchanger via a rich liquid pump. The cold-side fluid channel outlet of the rich-lean liquid heat exchanger is connected to the rich liquid inlet of the falling film tube in the falling film desorption tower. The liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower is connected to the hot-side fluid channel inlet of the rich-lean liquid heat exchanger via a lean liquid pump. The gas phase outlet at the top is connected to the hot-side fluid channel inlet of the product gas condenser via a product gas induced draft fan. The hot-side fluid channel outlet of the rich-lean liquid heat exchanger is connected to the fluid channel inlet of the lean liquid cooler. The cold source inlet and cold source outlet of the lean liquid cooler are respectively connected to the second cold source and form a loop. The fluid channel outlet is connected to the lean liquid inlet at the top of the absorption tower. The inlet of the lean liquid cooler is also connected to the absorbent replenishment channel. The cold source inlet and cold source outlet of the product gas condenser are respectively connected to the first cold source and form a loop. The gas phase outlet is connected to the carbon dioxide product channel. The condensate outlet is connected to the condensate inlet of the falling film tube at the top of the falling film desorption tower.

[0007] Preferably, the heat pump unit includes a condenser, a generator, an evaporator, an absorber, a solution throttling valve, a solution pump, a solution heat exchanger, and a water throttling valve; The solution outlet of the generator is connected to the hot-side fluid channel inlet of the solution heat exchanger, and the steam outlet is connected to the hot-side fluid channel inlet of the condenser; the hot-side fluid channel outlet of the solution heat exchanger is connected to the solution inlet of the absorber via a solution throttling valve, and the cold-side fluid channel outlet is connected to the solution inlet of the generator; the solution outlet of the absorber is connected to the cold-side fluid channel inlet of the solution heat exchanger via a solution pump; the hot-side fluid channel outlet of the condenser is connected to the cold-side fluid channel inlet of the evaporator via a water throttling valve, and the cold-side fluid channel outlet of the evaporator is connected to the steam inlet of the absorber; The condenser cooling water circulation channel enters from the hot-side fluid channel inlet of the evaporator and flows out from the hot-side fluid channel outlet.

[0008] Preferably, the flue gas flow channel passes sequentially through the hot-side fluid channels of the generator and evaporator, and finally connects to the flue gas inlet at the bottom of the absorption tower; the hot water circulation channel passes sequentially through the cold-side fluid channel of the absorber, the cold-side fluid channel of the condenser, the hot water pump and the jacket layer of the falling film desorption tower, and then returns to the cold-side fluid channel of the absorber, forming a closed loop.

[0009] Preferably, the hot water flowing in the condenser cooling water circulation channel is sourced from the power plant condenser cooling water.

[0010] Preferably, the absorption tower is a packed distillation tower; the packing in the packed distillation tower is one of Raschig rings, Pall rings, stepped rings, arc saddle packing, rectangular saddle packing, corrugated packing, corrugated mesh packing or metal saddle ring packing.

[0011] Preferably, the absorbent in the internal circulation path of the carbon capture unit is an amine-functionalized absorbent suitable for low-temperature regeneration; the working fluid pair in the heat pump unit is an aqueous solution of lithium bromide and water.

[0012] Preferably, the lean and rich liquid heat exchanger, condenser, evaporator and solution heat exchanger are all indirect wall heat exchangers.

[0013] Preferably, both the first cold source and the second cold source are natural cold sources or refrigeration units.

[0014] Secondly, the present invention provides an operation method for a carbon capture system utilizing the heat pump-assisted low-temperature falling film regeneration described in the first aspect, as follows: The working process of the carbon capture unit is as follows: After being cooled by the lean liquor cooler, the lean liquor enters from the lean liquor inlet at the top of the absorption tower. Inside the absorption tower, it undergoes heat and mass exchange with the flue gas to be treated, which enters the absorption tower through the flue gas flow channel. During this process, the lean liquor absorbs carbon dioxide from the flue gas, resulting in rich liquor and treated flue gas. The treated flue gas is discharged through the flue gas emission channel; the rich liquid, driven by the rich liquid pump, enters the lean-rich liquid heat exchanger through the cold side fluid channel inlet, where it exchanges heat with the lean liquid from the liquid phase product outlet of the falling film desorption tower, becoming a high-temperature rich liquid; the high-temperature rich liquid enters the falling film desorption tower through the rich liquid inlet, and desorbs carbon dioxide under the heating of hot water supplied in the jacket layer of the falling film desorption tower; the desorbed carbon dioxide and entrained absorbent components are extracted by the product gas induced draft fan and discharged through the gas phase outlet at the top of the desorption tower and enter the product gas condenser; the absorbent components in the gas phase are condensed in the product gas condenser. The absorbent is liquefied by exchanging heat with the first cold source and is discharged through the condensate outlet and returned to the falling film desorption tower. The remaining gas components are discharged through the gas phase outlet of the product gas condenser and collected through the carbon dioxide product flow channel. The desorbed absorbent solution is discharged as lean liquid from the liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower. It is then pumped by the lean liquid pump into the hot side fluid channel inlet of the lean-rich liquid heat exchanger, where the rich liquid upstream of the inlet of the falling film desorption tower is heated. The lean liquid after heat exchange in the lean-rich liquid heat exchanger is mixed with the absorbent solution replenished by the absorbent replenishment flow channel and enters the lean liquid cooler. After exchanging heat with the second cold source in the lean liquid cooler, it is fed into the absorption tower to complete the cycle. The working process of the heat pump unit is as follows: A dilute solution enters the generator's solution inlet from the cold-side fluid channel of the solution heat exchanger, where it exchanges heat with the high-temperature flue gas in the hot-side fluid channel, generating high-pressure steam and a concentrated solution. The high-pressure steam then enters the condenser's hot-side fluid channel through the generator's steam outlet, releasing heat to the cold-side fluid channel's hot water circulation channel, forming condensate. This condensate enters a water throttling valve, expands into low-pressure water, and then enters the evaporator's cold-side fluid channel, where it exchanges heat with the low-temperature flue gas and condenser cooling water in the hot-side fluid channel, evaporating into low-pressure steam. This low-pressure steam then enters the absorber's steam... The steam inlet completes the water working fluid circulation; the concentrated solution enters the hot-side fluid channel of the solution heat exchanger through the solution outlet of the generator, and after exchanging heat with the dilute solution in the cold-side fluid channel in the solution heat exchanger, it enters the solution inlet of the absorber through the solution throttling valve. In the absorber, it absorbs low-pressure steam from the gas phase inlet, and at the same time exchanges heat with the hot water supplied in the cold-side fluid channel of the absorber to generate a dilute solution. The solution then enters the cold-side fluid channel of the solution heat exchanger through the solution outlet of the absorber via the solution pump. After exchanging heat with the concentrated solution in the hot-side fluid channel in the solution heat exchanger, it enters the solution inlet of the generator to complete the solution working fluid circulation. The working process of the flue gas flow channel is as follows: High-temperature flue gas from the boiler enters the hot-side fluid channel of the generator, releasing heat and becoming medium-temperature flue gas; the medium-temperature flue gas enters the hot-side fluid channel of the evaporator, releasing heat and becoming low-temperature flue gas; the low-temperature flue gas enters the absorption tower through the flue gas inlet at the bottom of the absorption tower. The working process of the condenser cooling water circulation channel is as follows: Cooling water from the power plant condenser enters the hot-side fluid channel of the evaporator, releases heat, and then leaves the heat pump unit; The working process of the hot water circulation channel is as follows: Low-temperature hot water enters the cold-side fluid channel of the absorber, absorbing heat generated by the concentrated solution and low-pressure steam to become medium-temperature hot water. The medium-temperature hot water then enters the cold-side fluid channel of the condenser, absorbing the condensation heat of the high-pressure steam to become high-temperature hot water. Driven by the hot water pump, the high-temperature hot water enters the jacket layer of the falling film desorber. Inside the falling film desorber, it exchanges heat with the rich liquid through the heat exchange wall to become low-temperature hot water. Subsequently, it enters the cold-side fluid channel of the absorber through the jacket layer outlet of the falling film desorber, completing the cycle.

[0015] Compared with the prior art, the present invention has the following advantages: This invention combines absorption heat pump technology with a low-temperature regenerative carbon capture system, enabling efficient recovery of high-temperature waste heat from power plant flue gas and low-temperature waste heat from condensers. This provides a heat source for the falling film desorber, achieving low-temperature regeneration of the absorbent and reducing system energy consumption and power plant steam extraction. Compared to existing compression heat pumps or extraction-reboil methods, this invention's system consumes less electricity, has a more compact structure, and operates more stably. By circulating hot water, indirect heat exchange between the heat pump unit and the rich liquid is achieved, improving heat transfer efficiency and system reliability. This invention effectively enhances waste heat utilization and reduces the impact of carbon capture on power generation efficiency, resulting in significant energy saving and emission reduction effects. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a preferred structure of the system of the present invention.

[0017] In the diagram: Carbon capture unit 101; Heat pump unit 102; Absorber tower 1; Lean liquid cooler 2; Rich liquid pump 3; Lean and rich liquid heat exchanger 4; Falling film desorption tower 5; Product gas induced draft fan 6; Product gas condenser 7; Hot water pump 8; Lean liquid pump 9; Condenser 10; Generator 11; Evaporator 12; Absorber 13; Solution throttling valve 14; Solution pump 15; Solution heat exchanger 16; Water throttling valve 17; Flue gas flow channel 18; Flue gas discharge channel 19; Condenser cooling water circulation channel 20; Carbon dioxide product flow channel 21; First cold source 22; Absorbent replenishment channel 23; Second cold source 24; Hot water circulation channel 25. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0019] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0020] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0021] In the description of this invention, it should be understood that expressions such as "high temperature", "low temperature", "high pressure", and "low pressure" are used only for distinguishing purposes and should not be construed as indicating or implying relative importance or implicitly specifying the temperature or pressure limitation of the indicated technical features.

[0022] This invention provides a heat pump-assisted low-temperature falling film regeneration carbon capture system, which can be divided into five parts: a carbon capture unit 101, a heat pump unit 102, a flue gas flow channel 18, a condenser cooling water circulation channel 20, and a hot water supply circulation channel 25, as detailed below. Figure 1 As shown. The carbon capture unit 101 receives heat from the heat pump unit 102, absorbing and enriching carbon dioxide (CO2) in the flue gas within the flue gas duct 18. The heat pump unit 102 absorbs the high-temperature and low-temperature waste heat of the flue gas within the flue gas duct 18, as well as the low-temperature waste heat of the cooling water in the condenser cooling water circulation channel 20, and releases heat to the hot water circulation channel 25 at the absorber 13 and condenser 10. The hot water in the hot water circulation channel 25 absorbs the heat output from the heat pump unit 102 and enters the jacket layer of the falling film desorption tower 5 to exchange heat with the rich liquid in the falling film tubes. The flue gas duct 18, after sequentially heating the generator 11 and evaporator 12, is introduced into the flue gas inlet at the bottom of the absorption tower 1.

[0023] The structure and connection method of each unit will be explained in detail below.

[0024] As a preferred embodiment of the present invention, such as Figure 1 As shown, the carbon capture unit 101 mainly includes an absorption tower 1, a lean liquid cooler 2, a rich liquid pump 3, a lean and rich liquid heat exchanger 4, a falling film desorption tower 5, a product gas induced draft fan 6, a product gas condenser 7, a hot water pump 8, a lean liquid pump 9, a flue gas emission channel 19, a carbon dioxide product channel 21, a first cold source 22, an absorbent replenishment channel 23, and a second cold source 24, which together constitute an internal circulation path.

[0025] It should be noted that the absorbent refers to a liquid that has different solubilities for the components of a gas mixture and can selectively absorb one or more of them. The carbon capture unit 101 is filled with an absorbent solution for absorbing and desorbing carbon dioxide, specifically an amine-functionalized absorbent suitable for low-temperature regeneration.

[0026] In addition, the lean liquid cooler 2, the lean and rich liquid heat exchanger 4, and the product gas condenser 7 each have a cold-side fluid channel and a hot-side fluid channel that can form a heat exchange.

[0027] Specifically, the bottom of the absorption tower 1 is provided with a flue gas inlet connected to the flue gas flow channel 18 for introducing the flue gas to be treated. The top of the absorption tower 1 is provided with a flue gas outlet connected to the flue gas discharge channel 19 for discharging the treated flue gas.

[0028] Specifically, the bottom of the absorption tower 1 is also equipped with a rich liquid outlet, which is connected to the inlet of the rich liquid pump 3 via a pipeline. The outlet of the rich liquid pump 3 is connected to the inlet of the cold side fluid channel of the lean-rich liquid heat exchanger 4 via a pipeline. The outlet of the cold side fluid channel of the lean-rich liquid heat exchanger 4 is connected to the rich liquid inlet of the falling film tube of the desorption tower 5 via a pipeline.

[0029] Specifically, the liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower 5 is connected to the inlet of the lean liquid pump 9 via a pipeline, and the outlet of the lean liquid pump 9 is connected to the hot-side fluid channel inlet of the lean-rich liquid heat exchanger 4 via a pipeline. The gas phase outlet at the top of the falling film desorption tower 5 is connected to the hot-side fluid channel inlet of the product gas condenser 7 via the product gas induced draft fan 6. The hot-side fluid channel outlet of the lean-rich liquid heat exchanger 4 is connected to the fluid channel inlet of the lean liquid cooler 2 via a pipeline. The cold source inlet and cold source outlet of the lean liquid cooler 2 are respectively connected to the second cold source 24 via pipelines, forming a loop. The fluid channel outlet of the lean liquid cooler 2 is connected to the lean liquid inlet at the top of the absorption tower 1 via a pipeline. The fluid channel inlet of the lean liquid cooler 2 is also connected to the absorbent replenishment channel 23 via a pipeline. The cold source inlet and outlet of the product gas condenser 7 are connected to the first cold source 22 via pipelines, forming a loop. The gas phase outlet of the product gas condenser 7 is connected to the carbon dioxide product flow channel 21 via a pipeline. The condensate outlet of the product gas condenser 7 is connected to the condensate inlet of the falling film tube at the top of the falling film desorption tower 5 via a pipeline. The jacket inlet of the falling film desorption tower 5 is connected to the hot water circulation channel 25 via the hot water pump 8.

[0030] In this embodiment, the product gas condenser 7 has a gas-liquid separation function. The product gas condenser 7 condenses the mixed gas from the gas phase outlet of the falling film desorber 5 into condensate and CO2 product. The condensate flows back to the falling film desorber 5 through the condensate inlet of the falling film tube, and the CO2 product is discharged through the gas phase outlet of the product gas condenser 7 and collected through the carbon dioxide product flow channel 21.

[0031] In this embodiment, the absorption tower 1 is preferably a packed distillation tower. Selectable packing types for packed distillation towers include Raschig rings, Pall rings, stepped rings, arc saddle packing, rectangular saddle packing, corrugated packing, corrugated mesh packing, and metal saddle ring packing. Of course, in practical applications, different packing types can be selected based on temperature, pressure, material properties, equipment structure, and the requirements of the processed products to optimize the operating efficiency within the tower and improve separation efficiency.

[0032] In this embodiment, the falling film desorption tower 5 mainly includes falling film tubes and a jacket layer that form a heat exchange structure. The falling film tubes can have a spiral or straight pipe structure, used to receive the rich liquid and form a liquid film on the tube wall. The jacket layer is located outside the falling film tubes and is supplied with hot water, providing heat to the rich liquid through the heat exchange wall to achieve the regeneration of the rich liquid. The jacket layer ensures the stability and uniformity of the heat exchange efficiency through the uniform distribution of circulating hot water.

[0033] In this embodiment, the product gas induced draft fan 6 is connected to the pipeline between the gas phase outlet at the top of the falling film desorption tower 5 and the hot-side fluid channel inlet of the product gas condenser 7. The product gas induced draft fan 6 is used to draw in and reduce the partial pressure inside the desorption tower to synergistically promote low-temperature regeneration.

[0034] In addition, the first cold source 22 and the second cold source 24 can be provided by natural cold sources (such as water, wind, etc.) or by refrigeration units.

[0035] As a preferred embodiment of the present invention, such as Figure 1 As shown, the heat pump unit 102 mainly includes a condenser 10, a generator 11, an evaporator 12, an absorber 13, a solution throttling valve 14, a solution pump 15, a solution heat exchanger 16, and a water throttling valve 17, which together constitute an internal circulation path.

[0036] It should be noted that the working fluid pair in an absorption heat pump refers to the two different substances used in the absorption heat pump system (i.e., heat pump unit 102), typically including an absorbent and a working fluid. This working fluid pair works together to achieve cooling or heating functions by absorbing and releasing heat. In this embodiment, the heat pump unit 102 is filled with a solution-water working fluid pair for absorbing and releasing heat, specifically using a lithium bromide aqueous solution-water.

[0037] In addition, the condenser 10, generator 11, evaporator 12, absorber 13 and solution heat exchanger 16 each have a cold-side fluid channel and a hot-side fluid channel that can form a heat exchange.

[0038] Specifically, the solution outlet of generator 11 is connected to the hot-side fluid channel inlet of solution heat exchanger 16 via a pipe. The hot-side fluid channel outlet of solution heat exchanger 16 is connected to the inlet of solution throttle valve 14 via a pipe, and the outlet of solution throttle valve 14 is connected to the solution inlet of absorber 13 via a pipe. The solution outlet of absorber 13 is connected to the inlet of solution pump 15 via a pipe, and the outlet of solution pump 15 is connected to the cold-side fluid channel inlet of solution heat exchanger 16 via a pipe. The cold-side fluid channel outlet of solution heat exchanger 16 is connected to the solution inlet of generator 11 via a pipe.

[0039] Specifically, the steam outlet of generator 11 is connected to the hot-side fluid channel inlet of condenser 10 via a pipe, the hot-side fluid channel outlet of condenser 10 is connected to the inlet of water throttling valve 17 via a pipe, the outlet of water throttling valve 17 is connected to the cold-side fluid channel inlet of evaporator 12 via a pipe, and the cold-side fluid channel outlet of evaporator 12 is connected to the steam inlet of absorber 13 via a pipe.

[0040] Specifically, the condenser cooling water circulation channel 20 passes through the hot-side fluid channel of the evaporator 12, releases heat, and then leaves the heat pump unit 102. That is to say, the condenser cooling water circulation channel 20 enters the evaporator 12 from the inlet of the hot-side fluid channel and flows out from the outlet of the hot-side fluid channel of the evaporator 12.

[0041] As a preferred embodiment of the present invention, such as Figure 1As shown, the flue gas flow channel 18 passes through the hot-side fluid channels of the generator 11 and the evaporator 12 in sequence, and finally connects to the flue gas inlet at the bottom of the absorption tower 1.

[0042] In other words, the flue gas duct 18 enters the generator 11 through the hot side fluid channel inlet of the generator 11, and then flows out from the hot side fluid channel outlet of the generator 11; then it enters the evaporator 12 through the hot side fluid channel inlet of the evaporator 12 through the pipeline, and then flows out from the hot side fluid channel outlet of the evaporator 12; finally, it is connected to the flue gas inlet at the bottom of the absorption tower 1 through the pipeline.

[0043] As a preferred embodiment of the present invention, such as Figure 1 As shown, the hot water circulation channel 25 passes through the cold side fluid channel of the absorber 13, the cold side fluid channel of the condenser 10, and the jacket layer of the falling film desorption tower 5 in sequence, and then returns to the cold side fluid channel of the absorber 13, forming a closed loop.

[0044] In other words, the hot water circulation channel 25 enters the absorber 13 through the cold side fluid channel inlet of the absorber 13, and then flows out of the cold side fluid channel of the absorber 13; then it enters the condenser 10 through the cold side fluid channel inlet of the condenser 10 through the pipeline, and then flows out of the cold side fluid channel outlet of the condenser 10; then it enters the jacket layer of the falling film desorption tower 5 through the jacket layer inlet of the falling film desorption tower 5 through the pipeline, and then flows out of the jacket layer outlet of the jacket layer of the falling film desorption tower 5; then it returns to the cold side fluid channel of the absorber 13 through the pipeline.

[0045] In this embodiment, the lean and rich liquid heat exchanger 4 installed in the carbon capture unit 101 and the condenser 10, evaporator 12, and solution heat exchanger 16 installed in the heat pump unit 102 can all be indirect heat exchangers. Indirect heat exchangers can be classified into shell-and-tube heat exchangers, tube-and-shell heat exchangers, plate heat exchangers, and spray heat exchangers, depending on the form of the heat exchange surface. In practical applications, one type can be selected according to the requirements.

[0046] In this embodiment, the hot water flowing in the condenser cooling water circulation channel 20 is sourced from the power plant condenser cooling water.

[0047] The present invention also provides an operating method for the carbon capture system using the aforementioned heat pump-assisted low-temperature falling film regeneration. In this method, the system achieves low-energy carbon capture through the combined operation of the carbon capture unit 101 and the heat pump unit 102. The carbon capture unit 101 receives heat from the heat pump unit 102, absorbing and enriching CO2 in the flue gas. The heat pump unit 102 absorbs the high-temperature and low-temperature waste heat from the flue gas and the low-temperature waste heat from the condenser cooling water, outputting medium-temperature waste heat. The hot water in the hot water circulation channel 25 absorbs the heat output from the heat pump and enters the jacket layer of the falling film desorption tower 5, where it exchanges heat with the rich liquid in the falling film tubes through the heat exchange wall. The rich liquid forms a liquid film on the surface of the falling film tubes, absorbing heat from the hot water in the jacket layer, achieving low-temperature regeneration. The generated CO2 is extracted from the falling film desorption tower 5 by the product gas induced draft fan 6, improving desorption kinetics.

[0048] The specific steps of the above operating method are as follows: 1) The working process of the carbon capture unit 101 is as follows: The lean liquor, after being cooled by the lean liquor cooler 2, enters from the lean liquor inlet at the top of the absorption tower 1. Inside the absorption tower 1, it undergoes heat and mass exchange with the flue gas to be treated, which enters the absorption tower 1 through the flue gas flow channel 18. During this process, the lean liquor absorbs carbon dioxide from the flue gas, resulting in rich liquor and treated flue gas.

[0049] The treated flue gas is discharged through flue gas emission channel 19. Driven by the rich liquid pump 3, the rich liquid enters the lean-rich liquid heat exchanger 4 through the cold-side fluid channel inlet. Inside the heat exchanger 4, it exchanges heat with the lean liquid from the liquid-phase product outlet of the falling film desorber 5, becoming a high-temperature rich liquid. The high-temperature rich liquid enters the falling film desorber 5 through the rich liquid inlet, where it desorbs carbon dioxide under the heating of hot water supplied within the jacket layer. The desorbed carbon dioxide and entrained absorbent components are drawn by the product gas induced draft fan 6 and discharged through the gas phase outlet at the top of the desorber 5, entering the product gas condenser 7. The absorbent components in the gas phase exchange heat with the first cold source 22 in the product gas condenser 7, cooling and liquefying, and are discharged through the condensate outlet and returned to the falling film desorber 5. The remaining gas components are discharged through the gas phase outlet of the product gas condenser 7 and collected through the carbon dioxide product channel 21. The desorbed absorbent solution, as a lean solution, is discharged from the liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower 5. It is then pumped by the lean solution pump 9 into the hot-side fluid channel inlet of the lean-rich solution heat exchanger 4, where the rich solution upstream of the inlet of the falling film desorption tower 5 is heated. After heat exchange in the lean-rich solution heat exchanger 4, the lean solution mixes with the absorbent solution replenished by the absorbent replenishment channel 23 and enters the lean solution cooler 2. After heat exchange with the second cold source 24 in the lean solution cooler 2, it is fed into the absorption tower 1, completing the cycle.

[0050] It should be noted that during operation, absorbent solution can be added to the system through absorbent replenishment channel 23 to ensure a stable absorbent solution concentration in the system and balance the circulation loss.

[0051] 2) The working process of heat pump unit 102 is as follows: A dilute solution enters the solution inlet of generator 11 from the cold-side fluid channel of solution heat exchanger 16. Inside generator 11, it exchanges heat with the high-temperature flue gas in the hot-side fluid channel, generating high-pressure steam and a concentrated solution. The high-pressure steam enters the hot-side fluid channel of condenser 10 through the steam outlet of generator 11, releasing heat to the hot water circulation channel of the cold-side fluid channel, forming condensate. The condensate enters water throttling valve 17, expands into low-pressure water, and then enters the cold-side fluid channel of evaporator 12. Inside evaporator 12, it exchanges heat with the low-temperature flue gas and condenser cooling water in the hot-side fluid channel and evaporates into low-pressure steam. The low-pressure steam enters the steam inlet of absorber 13, completing the water working fluid circulation. The concentrated solution enters the hot-side fluid channel of the solution heat exchanger 16 through the solution outlet of the generator 11. After exchanging heat with the dilute solution in the cold-side fluid channel within the solution heat exchanger 16, it enters the solution inlet of the absorber 13 through the solution throttle valve 14. In the absorber 13, it absorbs low-pressure steam from the gas phase inlet and simultaneously exchanges heat with the hot water supplied in the cold-side fluid channel of the absorber 13, generating a dilute solution. This dilute solution then enters the cold-side fluid channel of the solution heat exchanger 16 through the solution outlet of the absorber 13 via the solution pump 15. After exchanging heat with the concentrated solution in the hot-side fluid channel within the solution heat exchanger 16, it enters the solution inlet of the generator 11, completing the solution working fluid cycle.

[0052] 3) The working process of flue gas duct 18 is as follows: High-temperature flue gas from the boiler enters the hot-side fluid channel of generator 11, releasing heat and becoming medium-temperature flue gas. The medium-temperature flue gas then enters the hot-side fluid channel of evaporator 12, releasing heat and becoming low-temperature flue gas. The low-temperature flue gas enters absorber 1 through the flue gas inlet at the bottom of absorber 1.

[0053] 4) The working process of condenser cooling water circulation channel 20 is as follows: Cooling water from the power plant condenser enters the hot-side fluid channel of the evaporator 12, releases heat, and then leaves the heat pump unit 102.

[0054] 5) The working process of the hot water circulation channel 25 is as follows: Low-temperature hot water enters the cold-side fluid channel of absorber 13, absorbing heat from the concentrated solution and low-pressure steam to become medium-temperature hot water. The medium-temperature hot water then enters the cold-side fluid channel of condenser 10, absorbing the condensation heat of high-pressure steam to become high-temperature hot water. Driven by hot water pump 8, the high-temperature hot water enters the jacket layer of falling film desorber 5. Inside the falling film desorber 5, it exchanges heat with the rich liquid through the heat exchange walls to become low-temperature hot water, which then enters the cold-side fluid channel of absorber 13 through the jacket layer outlet of the falling film desorber 5, completing the cycle.

[0055] In summary, this invention provides a heat pump-assisted low-temperature falling film desorption carbon capture system. It utilizes a lithium bromide-water absorption heat pump to recover high- and low-temperature waste heat from power plant flue gas and low-temperature waste heat from condenser cooling water, providing a regeneration heat source for the falling film desorption tower. The system heats the rich liquid in the falling film tubes by supplying hot water within the jacket layer of the falling film desorption tower, while simultaneously using a product gas induced draft fan to reduce the partial pressure within the tower, jointly promoting efficient CO2 desorption at low temperatures. This system significantly reduces its dependence on turbine extraction and minimizes the impact of the carbon capture process on the power plant's power generation efficiency. Through the coordinated operation of the carbon capture unit and the heat pump unit, the system achieves cascaded energy recovery and recycling. The heat pump unit uses the waste heat from the high-temperature section of the flue gas to drive the generator, outputting medium-temperature heat through the condenser and absorber to continuously heat the circulating hot water; the evaporator simultaneously absorbs the low-temperature waste heat from the low-temperature section of the flue gas and the low-temperature waste heat from the condenser cooling water, achieving comprehensive utilization of multiple waste heat sources. This system can reduce the extraction of steam from the turbine and drive the low-temperature falling film regeneration process by increasing the waste heat grade through a heat pump. This effectively reduces the regeneration energy consumption of the carbon capture system and realizes the efficient capture of CO2 in flue gas and the comprehensive utilization of waste heat resources from the power plant.

[0056] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A carbon capture system with heat pump-assisted low-temperature falling film regeneration, characterized in that, It includes a carbon capture unit (101), a heat pump unit (102), a flue gas flow channel (18), a condenser cooling water circulation channel (20), and a hot water supply circulation channel (25). The carbon capture unit (101) is used to receive heat from the heat pump unit (102), absorb and enrich carbon dioxide in the flue gas in the flue gas duct (18); the heat pump unit (102) is used to absorb the high temperature and low temperature waste heat of the flue gas in the flue gas duct (18), as well as the low temperature waste heat of the cooling water in the condenser cooling water circulation duct (20), and release heat to the hot water circulation duct (25) at the absorber (13) and condenser (10); the hot water in the hot water circulation duct (25) is used to absorb the heat output by the heat pump unit (102), and enter the jacket layer of the falling film desorption tower (5) to exchange heat with the rich liquid in the falling film tube; the flue gas duct (18) is used to heat the high temperature flue gas in sequence for the generator (11) and evaporator (12), and then enter the flue gas inlet at the bottom of the absorption tower (1).

2. The carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 1, characterized in that, The carbon capture unit (101) includes an absorption tower (1), a lean liquid cooler (2), a rich liquid pump (3), a lean and rich liquid heat exchanger (4), a falling film desorption tower (5), a product gas induced draft fan (6), a product gas condenser (7), and a lean liquid pump (9). The flue gas outlet at the top of the absorption tower (1) is connected to the flue gas discharge channel (19), and the rich liquid outlet at the bottom is connected to the cold-side fluid channel inlet of the lean-rich liquid heat exchanger (4) via the rich liquid pump (3). The cold-side fluid channel outlet of the lean-rich liquid heat exchanger (4) is connected to the rich liquid inlet of the falling film tube of the falling film desorption tower (5). The liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower (5) is connected to the hot-side fluid channel inlet of the lean-rich liquid heat exchanger (4) via the lean liquid pump (9), and the gas phase outlet at the top is connected to the hot-side fluid channel inlet of the product gas condenser (7) via the product gas induced draft fan (6). The lean-rich liquid heat exchanger (4) The hot side fluid channel outlet of the product gas condenser (7) is connected to the fluid channel inlet of the lean liquid cooler (2); the cold source inlet and cold source outlet of the lean liquid cooler (2) are connected to the second cold source (24) and form a loop, and the fluid channel outlet is connected to the lean liquid inlet at the top of the absorption tower (1); the inlet of the lean liquid cooler (2) is also connected to the absorbent replenishment channel (23); the cold source inlet and cold source outlet of the product gas condenser (7) are connected to the first cold source (22) and form a loop, the gas phase outlet is connected to the carbon dioxide product channel (21), and the condensate outlet is connected to the condensate inlet of the falling film tube at the top of the falling film desorption tower (5).

3. The carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 2, characterized in that, The heat pump unit (102) includes a condenser (10), a generator (11), an evaporator (12), an absorber (13), a solution throttle valve (14), a solution pump (15), a solution heat exchanger (16), and a water throttle valve (17). The solution outlet of the generator (11) is connected to the hot-side fluid channel inlet of the solution heat exchanger (16), and the steam outlet is connected to the hot-side fluid channel inlet of the condenser (10); the hot-side fluid channel outlet of the solution heat exchanger (16) is connected to the solution inlet of the absorber (13) via a solution throttle valve (14), and the cold-side fluid channel outlet is connected to the solution inlet of the generator (11); the solution outlet of the absorber (13) is connected to the cold-side fluid channel inlet of the solution heat exchanger (16) via a solution pump (15); the hot-side fluid channel outlet of the condenser (10) is connected to the cold-side fluid channel inlet of the evaporator (12) via a water throttle valve (17), and the cold-side fluid channel outlet of the evaporator (12) is connected to the steam inlet of the absorber (13); The condenser cooling water circulation channel (20) enters from the hot side fluid channel inlet of the evaporator (12) and flows out from the hot side fluid channel outlet.

4. The carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 3, characterized in that, The flue gas flow channel (18) passes through the hot side fluid channels of the generator (11) and evaporator (12) in sequence, and finally connects to the flue gas inlet at the bottom of the absorption tower (1); the hot water circulation channel (25) passes through the cold side fluid channel of the absorber (13), the cold side fluid channel of the condenser (10), the hot water pump (8) and the jacket layer of the falling film desorption tower (5) in sequence, and then returns to the cold side fluid channel of the absorber (13), forming a closed loop.

5. A carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 1, characterized in that, The hot water flowing in the condenser cooling water circulation channel (20) is sourced from the power plant condenser cooling water.

6. The carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 1, characterized in that, The absorption tower (1) is a packed distillation tower; the packing in the packed distillation tower is one of Raschig rings, Pall rings, stepped rings, arc saddle packing, rectangular saddle packing, corrugated packing, corrugated mesh packing or metal saddle ring packing.

7. The carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 1, characterized in that, The absorbent in the internal circulation path of the carbon capture unit (101) is an amine-functionalized absorbent suitable for low-temperature regeneration; the working fluid pair in the heat pump unit (102) is an aqueous solution of lithium bromide and water.

8. A carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 3, characterized in that, The lean and rich liquid heat exchanger (4), condenser (10), evaporator (12) and solution heat exchanger (16) are all indirect wall heat exchangers.

9. A carbon capture system with heat pump-assisted low-temperature falling film regeneration according to claim 2, characterized in that, The first cold source (22) and the second cold source (24) are both natural cold sources or refrigeration units.

10. A method for operating a carbon capture system utilizing the heat pump-assisted low-temperature falling film regeneration method as described in claim 4, characterized in that, Specifically as follows: The working process of the carbon capture unit (101) is as follows: After being cooled by the lean liquid cooler (2), the lean liquid enters from the lean liquid inlet at the top of the absorption tower (1) and undergoes heat and mass exchange with the flue gas to be treated that enters the absorption tower (1) through the flue gas flow channel (18) inside the absorption tower (1). In this process, the lean liquor absorbs carbon dioxide from the flue gas, resulting in rich liquor and treated flue gas; The treated flue gas is discharged through the flue gas discharge channel (19); the rich liquid, driven by the rich liquid pump (3), enters the lean-rich liquid heat exchanger (4) through the cold side fluid channel inlet, and exchanges heat with the lean liquid from the liquid phase product outlet of the falling film desorption tower (5) in the lean-rich liquid heat exchanger (4), and becomes a high-temperature rich liquid; the high-temperature rich liquid enters the falling film desorption tower (5) through the rich liquid inlet, and is desorbed by hot water supplied in the jacket layer of the falling film desorption tower (5). Carbon dioxide is discharged; the desorbed carbon dioxide and the entrained absorbent components are drawn by the product gas induced draft fan (6) and discharged through the gas phase outlet at the top of the desorption tower (5) and enter the product gas condenser (7); the absorbent components in the gas phase exchange heat with the first cold source (22) in the product gas condenser (7) and cool down and liquefy, and are discharged through the condensate outlet and flow back into the falling film desorption tower (5); the remaining gas components are discharged through the gas phase outlet of the product gas condenser (7) and collected through the carbon dioxide product flow channel (21); The desorbed absorbent solution is discharged as lean liquid from the liquid phase outlet of the falling film tube at the bottom of the falling film desorption tower (5). It is then pumped into the hot side fluid channel inlet of the lean-rich liquid heat exchanger (4) by the lean liquid pump (9). The rich liquid upstream of the inlet of the falling film desorption tower (5) is heated in the lean-rich liquid heat exchanger (4). The lean liquid after heat exchange in the lean-rich liquid heat exchanger (4) is mixed with the absorbent solution replenished by the absorbent replenishment channel (23) and then enters the lean liquid cooler (2). After heat exchange between the lean liquid cooler (2) and the second cold source (24), it is fed into the absorption tower (1) to complete the cycle. The working process of the heat pump unit (102) is as follows: A dilute solution enters the solution inlet of the generator (11) from the cold-side fluid channel of the solution heat exchanger (16). In the generator (11), it exchanges heat with the high-temperature flue gas in the hot-side fluid channel, generating high-pressure steam and a concentrated solution. The high-pressure steam enters the hot-side fluid channel of the condenser (10) through the steam outlet of the generator (11). In the condenser (10), it releases heat to the hot water circulation channel of the cold-side fluid channel, forming condensate. The condensate enters the water throttling valve (17), expands into low-pressure water, and then enters the cold-side fluid channel of the evaporator (12). In the evaporator (12), it exchanges heat with the low-temperature flue gas and condenser cooling water in the hot-side fluid channel and evaporates into low-pressure steam. The low-pressure steam enters the steam inlet of the absorber (13). The water working fluid circulation is completed; the concentrated solution enters the hot side fluid channel of the solution heat exchanger (16) through the solution outlet of the generator (11), and after exchanging heat with the dilute solution in the cold side fluid channel in the solution heat exchanger (16), it enters the solution inlet of the absorber (13) through the solution throttle valve (14). In the absorber (13), it absorbs the low-pressure steam from the gas phase inlet and at the same time exchanges heat with the hot water in the cold side fluid channel of the absorber (13) to generate a dilute solution. The solution enters the cold side fluid channel of the solution heat exchanger (16) through the solution outlet of the absorber (13) via the solution pump (15). After exchanging heat with the concentrated solution in the hot side fluid channel in the solution heat exchanger (16), it enters the solution inlet of the generator (11) to complete the solution working fluid circulation; The working process of the flue gas flow channel (18) is as follows: High-temperature flue gas from the boiler enters the hot-side fluid channel of the generator (11) and releases heat to become medium-temperature flue gas; the medium-temperature flue gas enters the hot-side fluid channel of the evaporator (12) and releases heat to become low-temperature flue gas; the low-temperature flue gas enters the absorption tower (1) through the flue gas inlet at the bottom of the absorption tower (1). The working process of the condenser cooling water circulation channel (20) is as follows: Cooling water from the power plant condenser enters the hot-side fluid passage of the evaporator (12), releases heat, and then leaves the heat pump unit (102). The working process of the hot water circulation channel (25) is as follows: Low-temperature hot water enters the cold-side fluid channel of the absorber (13), where it absorbs the heat generated by the concentrated solution and low-pressure steam, becoming medium-temperature hot water. The medium-temperature hot water then enters the cold-side fluid channel of the condenser (10), where it absorbs the condensation heat of the high-pressure steam, becoming high-temperature hot water. Driven by the hot water pump (8), the high-temperature hot water enters the jacket layer of the falling film desorption tower (5), where it exchanges heat with the rich liquid through the heat exchange wall and becomes low-temperature hot water. Subsequently, it enters the cold-side fluid channel of the absorber (13) through the jacket layer outlet of the falling film desorption tower (5), completing the cycle.

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