A large-temperature-rise slurry waste heat recovery composite heat pump heating system

Abstract

This invention discloses a high-temperature-rise slurry waste heat recovery composite heat pump heating system. The system includes a high-pressure flash condensation device (1), a low-pressure flash condensation device (3), an absorption heat pump (4), a cascade heat recovery compression refrigeration circuit, and a condensate tank (7). The slurry undergoes initial flash evaporation in the high-pressure flash condensation device (1), and the generated gas is absorbed by the condensate from the condensate tank (7). The slurry then enters the low-pressure flash condensation device (3) for multi-stage flash evaporation. The first-stage flash evaporation steam enters the evaporator (E) of the absorption heat pump (4). Simultaneously, the circuit consisting of the compressor (6), expansion valve (5), and the low-pressure condenser (as the evaporator) recovers the subsequent flash evaporation heat and also delivers it to the evaporator (E). Driven by an external heat source, the absorption heat pump (4) utilizes the low-temperature heat of the evaporator (E) to heat the heating circuit through the absorber (A) and condenser (C). This invention achieves efficient recovery of slurry waste heat and high-temperature-rise heating, and effectively solves the problems of non-condensable gas treatment and condensate reuse.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy engineering and waste heat recovery technology, specifically relating to a composite heat pump heating system for high temperature rise slurry waste heat recovery. Background Technology

[0002] Wet desulfurization slurry contains abundant waste heat, and its recovery and utilization is an important way to improve energy efficiency. Current mainstream technical solutions mainly include: 1) direct heat exchange between the slurry and the low-temperature medium through a partitioned heat exchanger; 2) using slurry flash evaporation combined with an absorption heat pump, utilizing the flash steam as the heat source for the heat pump evaporator; 3) replacing the absorption heat pump with a similar flash evaporation technology using an electric compression heat pump; 4) using slurry flash evaporation combined with an open-loop heat pump, allowing the flash steam to be absorbed and regenerated by the solution; 5) employing a two-stage flash evaporation technology combining high-pressure and low-pressure flash evaporation.

[0003] The above-mentioned technologies face a series of common challenges in engineering applications: First, the slurry is highly corrosive and prone to scaling, which leads to easy corrosion and blockage of the indirect heat exchanger, resulting in low heat exchange efficiency and poor reliability; Second, a large amount of non-condensable gases such as CO2 and SO2 dissolved in the slurry are released during flash evaporation, which seriously hinders steam condensation and leads to high power consumption of the vacuum pumping device in order to maintain the system vacuum; Third, it is difficult to simultaneously achieve the dual goals of "deep cooling of the slurry to increase the amount of waste heat extracted" and "significant temperature rise at the heating end to improve the heat energy grade", resulting in a contradiction between the depth of recovery and the system energy efficiency.

[0004] To address equipment blockage and corrosion issues, various flash heating pump technologies were employed to avoid direct contact between the slurry and the heat exchanger. To reduce the impact of non-condensable gases on the condensation process, open-loop heat pump technology was developed to allow them to be discharged with the solution, preventing accumulation. High-pressure flash evaporation was also used to pre-separate some non-condensable gases, reducing the subsequent vacuuming load. To achieve lower slurry outlet temperatures, electric compression heat pumps with lower evaporation temperatures were employed. However, these solutions all have limitations: the flash evaporation combined with absorption or electric compression heat pumps is still severely affected by non-condensable gases, resulting in high vacuuming power consumption, and the latter itself has high power consumption and limited temperature rise; while open-loop heat pumps avoid the influence of non-condensable gases, the system is complex and the slurry cooling is small; high-pressure flash evaporation technology, although reducing the volume of non-condensable gases, generates a high-pressure steam mixture requiring additional cold source treatment, increasing system complexity and energy consumption, and none of these solutions effectively solve the problem of efficient condensate recycling. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing slurry waste heat recovery technologies in terms of equipment reliability, non-condensable gas treatment, waste heat recovery depth, and system energy efficiency synergy. It provides a slurry waste heat recovery composite heat pump heating system that integrates high temperature rise, high-efficiency recovery, reliable operation, and condensate recycling. Its core lies in the synergy of multi-stage flash evaporation, condensate circulation absorption, and a thermoelectric composite heat pump to achieve efficient and stable extraction of waste heat from desulfurization slurry and significantly increase its temperature for external heating. This provides technical equipment support for deep energy saving and waste heat resource utilization in power plants or industrial processes.

[0006] To address the aforementioned problems, a first aspect of the present invention provides a high-temperature-rise slurry waste heat recovery composite heat pump heating system, the system comprising: a high-pressure flash condensation device (1) for performing preliminary flash evaporation cooling on desulfurized slurry from a slurry pool, and allowing the water vapor and non-condensable gases generated during flash evaporation to be absorbed or condensed by a cooling medium; a low-pressure flash condensation device (3) connected to the slurry outlet of the high-pressure flash condensation device (1), for performing multi-stage flash evaporation on the pre-cooled slurry to further cool it, and equipped with a low-pressure condenser for condensing at least a portion of the flash steam; an absorption heat pump (4) comprising a generator (G), an absorber (A), a condenser (C), and an evaporator (E), wherein the generator (G) is connected to an external heat source, and the evaporator (E) is connected to the first-stage flash steam outlet of the low-pressure flash condensation device (3) to receive the flash steam and condense it to release heat; and a cascade heat recovery compression refrigeration circuit comprising a compressor (6), an expansion valve (5), and the low-pressure condenser serving as its evaporator; The inlet of the compressor (6) is connected to the refrigerant vapor outlet of the low-pressure condenser, and its outlet is connected to the refrigerant side of the evaporator (E) of the absorption heat pump (4). This allows the refrigerant vapor generated in the low-pressure condenser to be pressurized by the compressor (6) and then condensed and released heat in the evaporator (E). The condensed liquid refrigerant is throttled by the expansion valve (5) and returns to the low-pressure condenser to absorb the condensation heat of the low-pressure flash vapor and evaporate, forming a cycle. The condensate tank (7) is used to collect water from the absorption heat pump. (4) Evaporator (E) and condensate of the low-pressure condenser; wherein the outlet of the condensate tank (7) is connected to the cooling medium inlet of the high-pressure flash condenser (1), and the condensate is used as a cooling medium to be introduced into the high-pressure flash condenser (1) to absorb or condense the flash gas therein; and the cooling medium from the high-pressure flash condenser (1) that has absorbed non-condensable gases is mixed with the cooled slurry flowing out from the low-pressure flash condenser (3) and returned to the slurry pool together.

[0007] The high-temperature-rise slurry waste heat recovery composite heat pump heating system provided in this application is based on the specific connection and coordinated operation of a high-pressure flash condenser (1), a low-pressure flash condenser (3), an absorption heat pump (4), a cascade heat recovery compression refrigeration circuit, and a condensate tank (7). The system performs preliminary flash evaporation of the slurry through the high-pressure flash condenser (1) and uses condensate from the condensate tank (7) as a cooling medium to treat it; the slurry is subjected to multi-stage flash evaporation through the low-pressure flash condenser (3), and the first-stage flash steam enters the evaporator (E) of the absorption heat pump (4), while the subsequent flash steam is recovered by the cascade heat recovery compression refrigeration circuit, which includes a compressor (6), an expansion valve (5), and the low-pressure condenser as an evaporator, and the recovered heat is also transported to the evaporator (E); the absorption heat pump (4), driven by an external heat source, uses the low-temperature heat collected by the evaporator (E) to heat the user's return water through its absorber (A) and condenser (C). The cooling medium from the high-pressure flash condenser (1) is eventually mixed with the cooled slurry from the low-pressure flash condenser (3) and returned to the slurry pool. Through the connection and coordination of the above components, the system achieves efficient recovery of slurry waste heat and high temperature rise heating.

[0008] Furthermore, the system also includes a vacuum pumping device (2), which is connected to the high-pressure flash condenser (1) and is used to extract non-condensable gases that have not been absorbed by the condensate.

[0009] Furthermore, the system also includes an alkali tank (8), which is connected to the condensate tank (7) via a valve and is used to add alkali to the condensate to enhance the absorption capacity of acidic non-condensable gases.

[0010] Furthermore, the high-pressure flash condensation device (1) adopts a direct contact heat exchange method, in which the condensate comes into direct contact with the flashed water vapor and non-condensable gases in the form of spray to carry out heat and mass exchange.

[0011] Furthermore, the high-pressure flash condenser (1) adopts a partitioned heat exchange method, and the condensate indirectly absorbs the condensation heat of the flash gas through the heat exchange wall.

[0012] Furthermore, the stepped heat recovery compression refrigeration circuit also includes a first branch, where a portion of the liquid refrigerant at the outlet of the expansion valve (5) is diverted to the high-pressure flash condenser (1) as its cold source. After absorbing heat and evaporating, it merges with the refrigerant vapor flowing out from the low-pressure condenser and enters the compressor (6).

[0013] Furthermore, the system also includes a heat exchanger (9), the hot side of which is connected to the high-pressure flash condenser (1) to provide a cold source for it; the cascade heat recovery compression refrigeration circuit also includes a second branch, a portion of the liquid refrigerant at the outlet of the expansion valve (5) is diverted to the cold side of the heat exchanger (9) to absorb the heat released from the hot side.

[0014] Furthermore, the return water from the heat user flows sequentially through the absorber (A) and condenser (C) of the absorption heat pump (4) and is heated before being output as water supply.

[0015] The above-described technical solution of the present invention has the following beneficial technical effects: 1. Achieve efficient and high-temperature-rise heating: Through system integration and multi-stage energy enhancement, the deep cooling of the slurry and the significant temperature rise at the external heating end are achieved in synergy, significantly improving the overall energy utilization efficiency.

[0016] 2. Effective treatment of non-condensable gases and reduction of energy consumption: The system innovatively utilizes condensate within the system to absorb flash gases, reducing the total amount of non-condensable gases at the source and significantly reducing the energy consumption for maintaining vacuum. Combined with optional alkaline solutions to enhance absorption, the economic efficiency is further optimized.

[0017] 3. Improve system energy efficiency and realize resource recycling: The multi-stage flash evaporation and cascade heat recovery process increases the amount of waste heat extracted while reducing the flow rate of the medium. Through the closed-loop mixing and reuse of condensate and slurry, water balance and resource utilization of waste heat and wastewater are realized.

[0018] 4. Enhanced system flexibility and operational stability: Provides multiple options for cold source configuration and heat exchange methods, enabling the system to adapt to different operating conditions and media characteristics, thereby improving regulation capability and operational reliability.

[0019] 5. Mature technology and wide applicability: Based on mature heat pumps and heat exchange units, the system process is clear and reliable. It is not only applicable to desulfurization slurry, but its principle can also be extended to other industrial low-grade waste heat recovery scenarios.

[0020] In summary, the technical solution of this invention, through a series of innovative system integration and process design, comprehensively solves the key problems existing in the current slurry waste heat recovery technology, such as equipment vulnerability, high energy consumption in non-condensable gas treatment, and difficulty in balancing waste heat recovery depth and heating temperature rise, and provides a high-efficiency, reliable, flexible and environmentally friendly waste heat recovery heating solution. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a composite heat pump heating system for high-temperature-rise slurry waste heat recovery in an embodiment of the present invention. Figure 2 yes Figure 1A schematic diagram of the system with an added alkali tank is shown. Figure 3 This is a schematic diagram of a composite heat pump heating system for high temperature rise slurry waste heat recovery using a partition wall high-pressure condenser in an embodiment of the present invention. Figure 4 This is a schematic diagram of a composite heat pump heating system for high temperature rise slurry waste heat recovery, which uses refrigerant diversion as a high-pressure cold source in an embodiment of the present invention. Figure 5 This is a schematic diagram of a composite heat pump heating system for high-temperature rise slurry waste heat recovery, which uses intermediate medium heat exchange as a high-pressure cold source in an embodiment of the present invention.

[0022] Figure label: 1: High-pressure flash condenser; 2: Vacuum pump; 3: Low-pressure flash condenser; 4: Absorption heat pump; 5: Expansion valve; 6: Compressor; 7: Condensate tank; 8: Alkali tank; 9: Heat exchanger; G: Generator; A: Absorber; C: Condenser; E: Evaporator. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0024] To address the aforementioned problems in existing technologies, this invention proposes a high-temperature-rise slurry waste heat recovery composite heat pump heating system. This system enables multi-stage deep flash evaporation of desulfurization slurry to fully extract waste heat, and utilizes condensate circulation to absorb the non-condensable gases generated during flash evaporation. Simultaneously, the recovered low-temperature heat is significantly amplified by coupling an absorption heat pump with a compression refrigeration circuit. During system operation, the slurry undergoes tiered cooling through high-pressure flash condensation and multi-stage low-pressure flash evaporation. The generated flash steam and recovered heat are collected in an absorption heat pump evaporator, where an external heat source-driven absorption heat pump converts it into high-grade heat energy for external heating. This solution, by employing flash heat exchange technology, avoids the blockage problem caused by direct contact between the slurry and the heat exchange surface, and significantly reduces the energy consumption for non-condensable gas treatment. Ultimately, it achieves a synergistic effect of deep slurry cooling and a large temperature rise for external heating, providing reliable technical equipment for the efficient recovery and high-grade utilization of industrial waste heat resources.

[0025] The following is combined with Figures 1 to 5 The present invention describes the high-temperature-rise slurry waste heat recovery composite heat pump heating system provided by the present invention.

[0026] Figure 1This is a schematic diagram of a composite heat pump heating system for high-temperature-rise slurry waste heat recovery in an embodiment of the present invention.

[0027] like Figure 1 As shown, this embodiment provides a high-temperature-rise slurry waste heat recovery composite heat pump heating system. The desulfurized slurry from the slurry tank first enters the high-pressure flash condensation unit 1 for preliminary flash cooling. Simultaneously, condensate from the condensate tank 7, as the cooling medium, is pumped into the high-pressure flash condensation unit 1. Preferably, the condensate is sprayed and directly contacts the flashed water vapor and non-condensable gases for heat exchange, completing preliminary heat recovery and non-condensable gas absorption. The pre-cooled slurry then enters the low-pressure flash condensation unit 3 for multi-stage deep flash evaporation. The steam from the first stage of flash evaporation is directly introduced into the evaporator E of the absorption heat pump 4 for condensation and heat release. Subsequent flashed steam is condensed in the low-pressure condenser within the low-pressure flash condensation unit 3, and the released condensation heat is used to evaporate the refrigerant flowing through it. The refrigerant vapor is then pressurized by compressor 6 and sent to evaporator E for condensation and heat release, thus forming a cascade heat recovery compression refrigeration loop including compressor 6, expansion valve 5, and low-pressure condenser, achieving efficient recovery and grade improvement of low-temperature heat. Absorption heat pump 4, driven by an external heat source supplied to its generator G, converts the low-temperature heat collected in evaporator E into high-grade heat energy through absorber A and condenser C, which is used to cascade heat the user-side return water, ultimately outputting high-temperature supply water. Finally, the cooling medium (i.e., condensate) flowing out of high-pressure flash condenser 1, having completed its absorption process, mixes with the deeply cooled slurry flowing out of low-pressure flash condenser 3, and both return to the slurry pool, forming a complete closed-loop material circulation within the system. To optimize operation, the system can also be equipped with a vacuum device 2 connected to high-pressure flash condenser 1 to extract residual non-condensable gases. Through the above coordinated operation, the system achieves efficient recovery and heating of slurry waste heat while simultaneously realizing condensate circulation and material balance.

[0028] Figure 2 for Figure 1 The diagram shows the structure of the system with an added alkali tank.

[0029] like Figure 2 As shown, in this embodiment... Figure 1 The system shown has been optimized by adding an alkali tank 8. The alkali tank 8 is connected to the condensate tank 7 via a valve and is used to add alkali solution (such as NaOH solution) to the condensate in the condensate tank 7 as needed. The purpose of this optimization is that, since the non-condensable gases generated by the flash evaporation of the slurry are mostly acidic gases such as CO2 and SO2, mixing alkali solution into the condensate, which serves as the cooling medium, can significantly enhance the chemical absorption capacity of these acidic gases due to its alkalinity.

[0030] When this alkalized condensate is pumped to the high-pressure flash condenser 1 and sprayed, it comes into full contact with the flash gas and undergoes a neutralization reaction, thereby significantly improving the absorption efficiency and capacity for non-condensable gases. This enhanced absorption process allows the system to more thoroughly remove non-condensable gases from the high-pressure flash section, directly reducing the total amount of waste gas that needs to be treated by the vacuum pump 2, effectively reducing its operating power consumption, and also improving the heat and mass transfer efficiency of the high-pressure flash condensation stage. The remaining process flows of the system, including the cascade flash evaporation of the slurry, heat recovery, thermoelectric combined boosting, and final heating, are all related to... Figure 1 The implementation remains consistent. By introducing the alkali tank 8, this embodiment, while maintaining the overall system architecture and closed-loop material circulation, specifically enhances the handling capacity of acidic non-condensable gases, making the system more adaptable and economical in the face of higher concentrations of acidic gases or more stringent operating requirements.

[0031] Figure 3 This is a schematic diagram of a high-temperature-rise slurry waste heat recovery composite heat pump heating system using a partitioned high-pressure condenser in an embodiment of the present invention.

[0032] like Figure 3 As shown, in this embodiment... Figure 1 Based on the system shown, another optimized solution is provided, the core improvement of which is: the high-pressure flash condenser 1 adopts an indirect heat exchange method. In this configuration, the condensate from the condensate tank 7 no longer comes into direct contact with the flash gas in the form of a spray, but flows through independent heat exchange pipes (or plates), and indirectly absorbs the condensation heat of the flash gas through the solid heat exchange wall surface.

[0033] The advantage of this scheme lies in achieving complete physical isolation between condensate and flash steam containing non-condensable gases. This indirect heat exchange method completely avoids condensate contamination by non-condensable gases (such as CO2 and SO2) and potential corrosion problems, making it particularly suitable for scenarios with complex slurry compositions, requirements for the purity of the cooling medium, or a desire to minimize subsequent water treatment. Although the mass transfer process is blocked, the highly efficient indirect heat exchanger still ensures sufficient heat recovery. The rest of the system, including the cascade flash evaporation of the slurry, the utilization of low-pressure flash steam, the operation of the cascade heat recovery compression refrigeration loop, and the heating process of the absorption heat pump, are all related to... Figure 1 The embodiments are completely identical. By employing a partitioned heat exchanger, this embodiment provides higher operational reliability and media compatibility while maintaining the core heat recovery and enhancement functions of the system, thus broadening the application scope of the system.

[0034] Figure 4 This is a schematic diagram of a composite heat pump heating system for high-temperature-rise slurry waste heat recovery, which uses refrigerant diversion as a high-pressure cold source in an embodiment of the present invention.

[0035] like Figure 4 As shown, in this embodiment... Figure 1 Based on the system shown, a key optimization scheme is provided, the core improvement of which is the addition of a first branch to the cascade heat recovery compression refrigeration circuit. A portion of the liquid refrigerant after being throttled and depressurized by the expansion valve 5 is directly diverted to the high-pressure flash condenser 1 through this branch, serving as its efficient cold source.

[0036] In this configuration, the cooling capacity required by the high-pressure flash condensation unit 1 is supplied by a low-temperature refrigerant. This portion of the refrigerant absorbs the condensation heat of the flash vapor in the heat exchanger of unit 1 and evaporates, then merges with the refrigerant vapor flowing out from the low-pressure condenser and enters the compressor 6 together to complete the entire refrigerant cycle. The core advantage of this scheme is that the refrigerant, as the working fluid, can have its flow rate independently adjusted as needed, without being limited by the amount of flash vapor in the slurry, and its evaporation temperature is usually significantly lower than the condensate temperature, thus providing stronger and more stable cooling capacity for the high-pressure flash condensation process. This allows the flash vapor to be condensed more quickly and thoroughly, significantly improving the heat exchange efficiency and non-condensable gas separation effect in the high-pressure flash stage, thereby helping to reduce the load on the subsequent vacuum pumping unit 2. The rest of the system, including the condensate system (condensate tank 7 and piping) as backup or auxiliary, and the cascade flash evaporation of the slurry, the heating process of the absorption heat pump 4, etc., are all related to... Figure 1 The implementation method remains consistent. By introducing refrigerant diversion as a high-pressure cold source, this embodiment achieves stronger control and better performance at the source of system heat recovery, thereby improving the energy efficiency and operational stability of the entire system.

[0037] Figure 5 This is a schematic diagram of a composite heat pump heating system for high-temperature rise slurry waste heat recovery, which uses intermediate medium heat exchange as a high-pressure cold source in an embodiment of the present invention.

[0038] like Figure 5 As shown, in this embodiment... Figure 1 Based on the system shown, a more stable and flexible optimization scheme is provided. Its core improvement lies in the addition of a heat exchanger 9 and its associated intermediate medium circulation loop. The hot-side medium from the high-pressure flash condenser 1 flows through the hot side of the heat exchanger 9, where it releases heat to the cold-side working medium. The cooled intermediate medium then returns to the high-pressure flash condenser 1 as a highly efficient cold source, absorbing the condensation heat of the flash steam and completing an independent intermediate medium circulation.

[0039] Meanwhile, the cascade heat recovery compression refrigeration circuit is equipped with a second branch. A portion of the cryogenic liquid refrigerant from the expansion valve 5 is diverted to the cold side of the heat exchanger 9, where it absorbs the heat released by the intermediate medium on the hot side and evaporates. The evaporated refrigerant vapor then returns to the compressor 6.

[0040] The significant advantages of this scheme are as follows: First, it avoids direct entry of high-pressure refrigerant into the high-pressure flash condenser 1, eliminating the potential impact of refrigerant on the flash evaporation environment of the slurry and improving the operational safety and stability of the main system. Second, through independent intermediate medium circulation, the system's cooling power adjustment of the high-pressure flash condenser 1 becomes more flexible and precise, better adapting to fluctuations in slurry flow rate or heat load. The remaining main components of the system, including the condensate system, the cascade flash evaporation process of the slurry, and the heating function of the absorption heat pump 4, are all related to... Figure 1 The implementation examples remain consistent. This example introduces an intermediate heat exchange medium, which, while ensuring efficient heat recovery, gives the system greater operational flexibility and reliability.

[0041] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A high-temperature-rise slurry waste heat recovery composite heat pump heating system, characterized in that, include: High-pressure flash condenser (1) is used to perform preliminary flash condensation cooling on desulfurized slurry from slurry pool, and to allow the water vapor and non-condensable gases generated by flash condensation to be absorbed or condensed by the cooling medium. The low-pressure flash condenser (3) is connected to the slurry outlet of the high-pressure flash condenser (1) and is used to perform multi-stage flash evaporation on the slurry that has been initially cooled to further cool it down. It is also equipped with a low-pressure condenser to condense at least a portion of the flash steam. An absorption heat pump (4) includes a generator (G), an absorber (A), a condenser (C), and an evaporator (E), wherein the generator (G) is connected to an external heat source, and the evaporator (E) is connected to the first-stage flash steam outlet of the low-pressure flash condensation device (3) to receive the flash steam and condense it to release heat. The cascade heat recovery compression refrigeration circuit includes a compressor (6), an expansion valve (5), and a low-pressure condenser as its evaporator; the inlet of the compressor (6) is connected to the refrigerant vapor outlet of the low-pressure condenser, and its outlet is connected to the refrigerant side of the evaporator (E) of the absorption heat pump (4), so that the refrigerant vapor generated in the low-pressure condenser is pressurized by the compressor (6) and condenses and releases heat in the evaporator (E); the condensed liquid refrigerant is throttled by the expansion valve (5) and returns to the low-pressure condenser to absorb the condensation heat of the low-pressure flash vapor and evaporate, forming a cycle; A condensate tank (7) is used to collect condensate from the evaporator (E) and the low-pressure condenser of the absorption heat pump (4); The outlet of the condensate tank (7) is connected to the cooling medium inlet of the high-pressure flash condenser (1), and the condensate is used as a cooling medium to be introduced into the high-pressure flash condenser (1) to absorb or condense the flash gas therein; and The cooling medium from the high-pressure flash condenser (1) that has absorbed non-condensable gases mixes with the cooled slurry flowing out from the low-pressure flash condenser (3) and returns together to the slurry pool.

2. The system according to claim 1, wherein, The system also includes a vacuum pumping device (2), which is connected to the high-pressure flash condenser (1) and is used to extract non-condensable gases that have not been absorbed by the condensate.

3. The system according to claim 1, wherein, The system also includes an alkali tank (8), which is connected to the condensate tank (7) via a valve and is used to add alkali to the condensate to enhance the absorption capacity of acidic non-condensable gases.

4. The system according to claim 1, wherein, The high-pressure flash condenser (1) adopts a direct contact heat exchange method, in which the condensate comes into direct contact with the flashed water vapor and non-condensable gas in the form of spray to carry out heat and mass exchange.

5. The system according to claim 1, wherein, The high-pressure flash condenser (1) adopts a partition wall heat exchange method, and the condensate indirectly absorbs the condensation heat of the flash gas through the heat exchange wall.

6. The system according to claim 1, wherein, The stepped heat recovery compression refrigeration circuit also includes a first branch, where a portion of the liquid refrigerant at the outlet of the expansion valve (5) is diverted to the high-pressure flash condenser (1) as its cold source. After absorbing heat and evaporating, it merges with the refrigerant vapor flowing out from the low-pressure condenser and enters the compressor (6).

7. The system according to claim 1, wherein, The system also includes a heat exchanger (9), the hot side of which is connected to the high-pressure flash condenser (1) to provide a cold source for it; the cascade heat recovery compression refrigeration circuit also includes a second branch, a portion of the liquid refrigerant at the outlet of the expansion valve (5) is diverted to the cold side of the heat exchanger (9) to absorb the heat released from the hot side.

8. The system according to claim 1, wherein, The return water from the heat user flows sequentially through the absorber (A) and condenser (C) of the absorption heat pump (4) and is heated before being output as water supply.

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