A device and method for removing non-condensable gases coupled with flash heat recovery under negative pressure

Abstract

The application provides a device and method for removing non-condensable gas under negative pressure coupled with flash heat utilization, and belongs to the technical field of energy saving. The device comprises a heat extractor, a desulfurization tower, a flash device and a heat pump connected in sequence; the flash device comprises a first flash tank and a second flash tank communicated through a flow-through device; the heat extractor and the heat pump are communicated through an auxiliary heater; and the heat pump is communicated with a heat supply pipe network. A large amount of non-condensable gas in the slurry is separated out in the first flash tank, and only low-temperature steam is flashed out from the slurry in the second flash tank under vacuum negative pressure; the low-temperature steam enters the heat pump evaporator to change phase, and the phase change heat can be fully absorbed by the heat pump. The sensible heat of flue gas before the absorption tower is extracted as a driving heat source of the heat pump, so that the flue gas waste heat is effectively utilized to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy saving, and particularly relates to a device and method for removing non-condensable gas under negative pressure and coupling flash evaporation of waste heat. BACKGROUND

[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission by the patent applicant(s) that this information constitutes prior art.

[0003] Coal-fired heating in autumn and winter will cause an increase in atmospheric pollutant emissions, which is one of the reasons for the serious winter haze. Waste heat heating is an important technical means for treating winter haze. Waste heat heating is based on the waste heat of high-energy-consuming industrial enterprises such as power plants and steel plants, and can stably and effectively meet the heating needs of surrounding residents in autumn and winter after being warmed by a heat pump, thereby greatly reducing the consumption of coal-fired heating and reducing the emission of atmospheric pollutants.

[0004] Among all the heat losses of the boiler system, the flue gas loss accounts for more than 50% of the total heat loss. Most coal-fired power plants use wet desulfurization process, and a large amount of water evaporates into the flue gas during the desulfurization process. The flue gas is in a saturated state after desulfurization, and the sensible heat of the flue gas is converted into latent heat of water vapor. Deep utilization of the latent heat of flue gas has important practical significance for energy saving and emission reduction, water saving, and environmental pollution reduction. SUMMARY

[0005] Based on the current technical status, the purpose of the present application is to provide a device and method for removing non-condensable gas under negative pressure and coupling flash evaporation of waste heat, which can efficiently remove non-condensable gas in slurry, avoid the influence of non-condensable gas on the heat efficiency of an absorption heat pump, and at the same time, the condensed water quality of the steam exhausted by the slurry is high, which can supplement the heat network system and the desulfurization system, and plays a significant role in water saving.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] In a first aspect, a device for removing non-condensable gas under negative pressure and coupling flash evaporation of waste heat comprises a heat extractor, a desulfurization tower, a flash evaporation device, and a heat pump connected in sequence. The flash evaporation device comprises a primary flash evaporation tank and a secondary flash evaporation tank connected by a flow-through device. The heat extractor and the heat pump are connected by an auxiliary heater. The heat pump is connected to a heat supply pipe network.

[0008] Optionally, the slurry outlet of the desulfurization tower is communicated with the flash spray layer of the primary flash tank, the primary flash tank comprises a primary slurry pool, the primary slurry pool is communicated with a secondary flash tank through a flow-through device; the secondary flash tank comprises a secondary slurry pool, and the secondary slurry pool is communicated with the slurry spray device of the desulfurization tower; most of the non-condensable gas is separated out in the primary flash tank, the non-condensable gas contained in the primary slurry in the primary flash tank is greatly reduced, and the flash steam (low-temperature steam) in the secondary flash tank is completely formed by the primary slurry and does not contain non-condensable gas, thereby avoiding the non-condensable gas from entering the heat pump evaporator to affect the heat exchange efficiency and causing the COP value of the heat pump to deviate from the design value.

[0009] In a second aspect, a negative pressure non-condensable gas removal and flash heat utilization method based on the above negative pressure non-condensable gas removal and flash heat utilization device comprises the following processes:

[0010] S1, the desulfurization slurry accumulated in the desulfurization tower enters the primary flash tank, is converted into primary slurry and non-condensable gas, the primary slurry enters the secondary flash tank through a flow-through device, is converted into secondary slurry and low-temperature steam, the low-temperature steam releases latent heat in the heat pump, and the secondary slurry returns to the desulfurization tower;

[0011] S2, the heat extractor absorbs the heat of the original flue gas entering the desulfurization tower to heat the circulating medium, and the circulating medium is input into the heat pump as a driving heat source of the heat pump;

[0012] S3, the heat pump realizes heating through the heat supply pipe network.

[0013] The present application has the following beneficial effects:

[0014] 1. The present application provides a primary slurry flash tank for removing non-condensable gas, eliminating the influence on the operation of the vacuum system and the output of the heat pump. A large amount of non-condensable gas is separated out in the primary flash tank, the primary vacuum pump extracts the non-condensable gas and discharges it to the atmosphere, the slurry after the removal of non-condensable gas in the primary flash system enters the secondary flash tank, the slurry in the secondary flash tank is only flashed to low-temperature steam under vacuum negative pressure, the low-temperature steam enters the heat pump evaporator to change phase, and the phase change heat can be fully absorbed by the heat pump. The sensible heat of the flue gas before the absorption tower is extracted as the driving heat source of the heat pump, the flue gas waste heat is used to the maximum extent, and the energy consumption of the flash system is reduced. A steam auxiliary heater is arranged on the hot water pipeline of the heat extractor. When the heat extraction amount of the heat extractor is insufficient and the COP of the heat pump is lower than the design value, the steam auxiliary heater is supplied with steam to supplement the driving heat required by the heat pump.

[0015] 2. The design of the heat pump system can meet the needs of large flow and low flow heating water respectively, and ensure the safe and stable operation of the heat pump. In the heating season, the heating capacity heats the large flow heat network water; in the non-heating season, the heat pump heating capacity is used to heat the low flow boiler condensate water and the low flow air heater. The heat pump output under variable conditions is mainly realized by the logic of multi-objective PID control. The outlet temperature of the heating water is set as the main adjustment target of the heat pump in the control system, and the control system will calculate and evaluate the various working parameters of the heat pump under the new boundary conditions, realize the safe and independent adjustment of the heat pump under variable conditions, and meet the output requirements of the user. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of the application, and their

[0017] Figure 1 Structure schematic diagram of the device for removing non-condensable gas coupled with flash heat utilization under negative pressure in Example 1.

[0018] 1, heat absorber; 2, desulfurization tower; 3, slurry spraying device; 4, slurry pump; 5, bypass valve; 6, return regulating valve; 7, flash tank slurry inlet regulating valve; 8, primary flash tank; 9, cyclone demisting device; 91, cyclone plate; 92, cyclone outer wall; 93, cyclone sub-center cylinder; 94, cyclone sub-separator; 10, flash spray layer; 11, primary slurry pool; 12, low-temperature steam pipeline; 13, secondary slurry pool; 14, primary vacuum pump; 15, slurry return pump; 16, secondary vacuum pump; 17, total vapor-liquid separator; 18, heat pump; 19, condensate water heat exchanger; 20, air heater heat exchanger; 21, primary gas-liquid separator; 22, secondary gas-liquid separator; 23, steam auxiliary heater on-off valve; 24, steam auxiliary heater bypass valve; 26, steam auxiliary heater; 27, steam regulating valve; 28, trap; 29, flow-through device; 30, secondary flash tank. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0020] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0021] A device for removing non-condensable gas coupled with flash heat utilization under negative pressure, comprising a heat extractor, a desulfurization tower, a flash device and a heat pump connected in sequence; the flash device comprises a first flash tank and a second flash tank connected by a flow-through device; the heat extractor is connected with the heat pump through an auxiliary heater; and the heat pump is connected with a heat supply pipe network.

[0022] Through the above arrangement, a large amount of non-condensable gas in the slurry is precipitated in the first flash tank, and the non-condensable gas is extracted by a first vacuum pump and discharged into the atmosphere. After the non-condensable gas is removed in the first flash system, the slurry enters the second flash tank. The slurry in the second flash tank only flashes low-temperature steam under vacuum negative pressure. The low-temperature steam enters the heat pump evaporator to change phase, and the phase change heat can be fully absorbed by the heat pump. Since the non-condensable gas does not enter the heat pump, the efficiency of the heat pump is stable and easy to control.

[0023] Optionally, the slurry outlet of the desulfurization tower is connected with the flash spray layer of the first flash tank, the first flash tank comprises a first slurry pool, and the first slurry pool is connected with the second flash tank through a flow-through device; the second flash tank comprises a second slurry pool, and the second slurry pool is connected with the slurry spray device of the desulfurization tower. Most of the non-condensable gas is separated out in the first flash tank, the non-condensable gas contained in the first slurry in the first flash tank is greatly reduced, and the low-temperature steam in the second flash tank is completely formed by the first slurry and basically does not contain non-condensable gas, thereby avoiding the non-condensable gas from entering the heat pump evaporator to affect the heat exchange efficiency and causing the COP value of the heat pump to deviate from the design value.

[0024] Optionally, the first flash tank is connected with a first vacuum pump to form negative pressure.

[0025] Optionally, a cyclone demisting device is arranged in the first flash tank to remove the liquid droplets entrained in the non-condensable gas.

[0026] Optionally, the cyclone demisting device is composed of a cyclone plate, a cyclone outer wall, a cyclone sub-center cylinder and a cyclone sub-separator. The demisting mechanism of the cyclone demisting device is that after the gas flow carrying a large amount of liquid droplets passes through the cyclone sub, the direction of the gas flow changes to produce a rotating gas flow. The pursuit effect of large liquid droplets and small liquid droplets causes the liquid droplets to grow, thereby achieving the effect of demisting.

[0027] Optionally, a primary gas-liquid separator is arranged between the primary flash tank and the primary vacuum pump, for removing secondary entrained mist from the non-condensable gas, to avoid adverse effects on the vacuum pump.

[0028] Optionally, the secondary flash tank is connected to the secondary vacuum pump through the heat pump, to ensure that the secondary flash tank flashes out the required flow rate, temperature and pressure of the low-temperature steam under negative pressure, the flashed-out low-temperature steam enters the evaporator of the heat pump through a low-temperature steam pipeline, and the heat pump absorbs the heat of the steam.

[0029] Optionally, a secondary gas-liquid separator is arranged between the heat pump and the secondary vacuum pump, for preventing a small amount of non-condensable gas from carrying liquid droplets to affect the output of the secondary vacuum pump.

[0030] Optionally, the auxiliary heater is a steam auxiliary heater, which is connected to an external steam source; when the heat extracted by the heat extractor is insufficient to cause the COP of the heat pump to be lower than the design value, the steam auxiliary heater is connected to the steam source to supplement the required driving heat of the heat pump.

[0031] Optionally, the heat pump is connected to a heating pipe network, for winter heating.

[0032] Optionally, the heat pump is connected to a warm air heater heat exchanger, for heat exchange with a boiler warm air heater pipeline, to realize waste heat utilization in seasons without heating.

[0033] Optionally, the heat pump is connected to a condensate water heat exchanger, for heat exchange with a boiler condensate water pipeline, to realize waste heat utilization in seasons without heating.

[0034] Optionally, the primary vacuum pump and the secondary vacuum pump are connected to the atmosphere through a total gas-liquid separator; the total gas-liquid separator is arranged to prevent residual liquid droplets discharged into the atmosphere from polluting the environment when the ambient temperature is low.

[0035] A negative pressure non-condensable gas removal and coupling flash waste heat utilization method based on the above-described device, comprising the following processes:

[0036] S1, the desulfurization slurry accumulated in the desulfurization tower enters the primary flash tank, and is converted into primary slurry and non-condensable gas; the primary slurry enters the secondary flash tank through a flow device, and is converted into secondary slurry and low-temperature steam; the low-temperature steam enters the heat pump to release latent heat; and the secondary slurry returns to the desulfurization tower.

[0037] S2, the heat extractor absorbs the heat of the original flue gas entering the desulfurization tower to heat the circulating medium; and the circulating medium is input into the heat pump as a driving heat source of the heat pump.

[0038] S3, the heat pump realizes heating through a heat supply pipe network.

[0039] Optionally, in S1, the non-condensable gas and the fog droplets are separated from the first gas-liquid separator through a cyclone demisting device, and the non-condensable gas is discharged through a first vacuum pump.

[0040] Optionally, in S1, the condensate formed after the low-temperature steam releases latent heat is supplemented into an auxiliary heating pipeline or a heat network pipeline.

[0041] Optionally, when the heat of the heat exchanger in S2 is insufficient, an auxiliary heater is started to heat the circulating medium.

[0042] Embodiment 1

[0043] The desulfurization slurry of the wet desulfurization tower contains a large amount of non-condensable gases such as CO2 and N2. In the vacuum negative pressure flash evaporation process, a large amount of non-condensable gases will be separated from the slurry and enter the heat pump system together with the low-temperature steam. In the process of releasing latent heat of the low-temperature steam, the non-condensable gases will not condense and continue to exist in the form of gas. The non-condensable gases will affect the stable operation of the entire flash tank vacuum system and reduce the heat pump output.

[0044] The embodiment provides a device for removing non-condensable gases under negative pressure and coupling flash evaporation residual heat utilization, as shown in Figure 1 The device comprises, in sequence, a heat exchanger 1, a desulfurization tower 2, a flash evaporation device, and a heat pump 18. The flash evaporation device comprises a first flash tank 8 and a second flash tank 30 which are communicated through a flow-through device 29. The heat exchanger 1 is communicated with the heat pump 18 through a steam auxiliary heater 26. The heat pump 18 is communicated with a heat supply pipe network.

[0045] A large amount of non-condensable gases in the slurry in the first flash tank 8 are separated, and a first vacuum pump 14 is used to extract the non-condensable gases to be discharged into the atmosphere. The slurry after removal of the non-condensable gases in the first flash evaporation system enters the second flash tank 30. The slurry in the second flash tank 30 is only flashed to produce low-temperature steam under vacuum negative pressure. The low-temperature steam enters the evaporator of the heat pump 18 to change phase, and the phase change heat can be fully absorbed by the heat pump 18. Since the non-condensable gases do not enter the heat pump 18, the efficiency of the heat pump 18 is stable and easy to control.

[0046] The slurry outlet of the desulfurization tower 2 is connected with the flash spray layer 10 of the first flash tank 8 through a slurry pump 4. The first flash tank 8 comprises a first slurry pool 11, and the first slurry pool 11 is connected with a second flash tank 30 through a flow-through device 29. The second flash tank 30 comprises a second slurry pool 13, and the second slurry pool 13 is connected with the slurry spray device 3 of the desulfurization tower 2. Most of the non-condensable gas is separated in the first flash tank 8, the non-condensable gas dissolved in the first slurry accumulated in the first slurry pool 11 is greatly reduced, and the low-temperature steam in the second flash tank 30 is completely formed by the first slurry and does not contain the non-condensable gas, thereby avoiding the non-condensable gas from entering the evaporator of the heat pump 18 to affect the heat exchange efficiency and cause the COP value of the heat pump 18 to deviate from the design value.

[0047] The flow-through device 29 comprises a plurality of flow-through holes with different diameters, so that the slurry in the first slurry pool 11 enters the second flash tank 30 and realizes the atomization of the slurry in the form of a screen structure. In the design, the slurry in the first slurry pool 11 is not allowed to flow into the second flash tank 30 quickly to prevent the liquid level of the first slurry pool 11 from being maintained, and the slurry is not allowed to be scaled in the flow-through device 29 and to be atomized in the second flash tank 30.

[0048] The flash tank inlet adjustment valve 7 is arranged between the slurry outlet of the desulfurization tower 2 and the flash spray layer 10. The slurry return pump 15 and the return adjustment valve 6 are arranged between the second slurry pool 13 and the slurry spray device 3 of the desulfurization tower 2. The inlet of the slurry spray device 3 is connected with the slurry outlet pipeline of the desulfurization tower 2 through a pipeline provided with a bypass valve 5, which is used to adjust the proportion of the desulfurization slurry of the desulfurization tower 2 entering the first flash tank 8 and the proportion of the second slurry in the second slurry pool 13 flowing back into the desulfurization tower 2.

[0049] The first slurry pool 11 is used as a buffer pool of the slurry. The design of the slurry pool considers that the angle between the slurry pool slope and the horizontal plane is 15°, which can stabilize the negative pressure of the first flash tank 8 and ensure that the slurry is not deposited.

[0050] The second slurry pool 13 is used as a buffer pool of the slurry. The design of the slurry pool considers that the angle between the slurry pool slope and the horizontal plane is 20°, which can stabilize the negative pressure of the second flash tank 30 and ensure that the slurry is not deposited. The first and second flash tanks are arranged in a high position. The slurry return pump 15 is arranged below the second slurry pool 13. After being flashed, the temperature of the slurry is reduced by 5-10°C. The cold slurry returns to the slurry spray device 3 through the slurry return pump 15 to be atomized and exchanged with the saturated wet flue gas in the desulfurization tower 2 to absorb the latent heat of vaporization in the wet flue gas. The flow of the cold slurry exchanged with the saturated wet flue gas is controlled through the return adjustment valve 6 to achieve the best energy-saving effect.

[0051] The first flash tank 8 is connected with a first vacuum pump 14, and the negative pressure is formed through the first vacuum pump 14.

[0052] A cyclone demisting device 9 is arranged in the primary flash tank 8, and is used to remove the liquid droplets entrained in the non-condensed gas discharged from the primary flash tank 8.

[0053] The cyclone demisting device 9 is composed of a cyclone plate, a cyclone outer wall, a cyclone sub-center cylinder and a cyclone sub-separator. The cyclone sub-center cylinder can rotate around a central axis, and a plurality of cyclone plates are mounted on the periphery of the cyclone sub-center cylinder. The cyclone plate is surrounded by the cyclone outer wall as a fixing device. The cyclone plate, the cyclone outer wall and the cyclone sub-center cylinder form a cyclone sub, which is installed in a frame composed of a plurality of cyclone sub-separators. The cyclone plates of adjacent two cyclone subs are in the clockwise direction or the counterclockwise direction, so that the intersection coupling area of the adjacent two cyclone subs produces a gas flow counter-current effect. A large number of small liquid droplets in the gas flow collide with small liquid droplets in the oncoming gas flow, resulting in primary coalescence, secondary coalescence or even multiple coalescence between the liquid droplets and the liquid droplets, thereby forming large liquid droplet particles, and achieving the best demisting efficiency. The demisting mechanism of the cyclone demisting device 9 is that after the gas flow carrying a large number of liquid droplets passes through the cyclone sub, the direction of the gas flow changes, a rotating gas flow is generated, and the pursuit effect of large liquid droplets and small liquid droplets causes the liquid droplets to grow, thereby achieving the effect of demisting.

[0054] A primary gas-liquid separator 21 is arranged between the primary flash tank 8 and the primary vacuum pump 14, and is used to remove the secondary entrained mist droplets in the non-condensed gas, so as to avoid the adverse effects of the mist droplets on the vacuum pump.

[0055] The secondary flash tank 30 is connected to the secondary vacuum pump 16 through the heat pump 18, so as to ensure that the secondary flash tank 30 flashes out the required flow, temperature and pressure of the low-temperature steam under negative pressure. The flashed low-temperature steam enters the evaporator of the heat pump 18 through the low-temperature steam pipeline 12, and the heat pump 18 absorbs the heat of the low-temperature steam. The condensed water formed by the low-temperature steam is supplemented into the auxiliary heating pipeline or the heat network pipeline.

[0056] A secondary gas-liquid separator 22 is arranged between the heat pump 18 and the secondary vacuum pump 16, and is used to prevent a small amount of non-condensed gas carrying liquid droplets from affecting the output of the secondary vacuum pump 16.

[0057] The steam auxiliary heater 26 is an auxiliary heater, and is connected to the external source steam through a steam regulating valve 27 and a trap 28. When the heat extraction of the heat extractor 1 is insufficient and the COP of the heat pump is lower than the design value, the steam auxiliary heater 26 is connected to the steam to supplement the required driving heat of the heat pump 18. The flow of the steam is controlled by the steam regulating valve 27, and the condensed water of the steam after work is discharged through the trap 28. The steam auxiliary heater 26 is provided with steam auxiliary heater on-off valves 23 at the front and rear ends, and is connected in parallel with a steam auxiliary heater bypass valve 24. By adjusting the steam auxiliary heater bypass valve 24 and the two steam auxiliary heater on-off valves 23, the steam auxiliary heater 26 can be switched in / out.

[0058] The heat pump 18 is connected to the heat supply pipe network for winter heating.

[0059] The heat pump 18 is connected to the warm air heater heat exchanger 20 for heat exchange with the boiler warm air heater pipe, so as to realize waste heat utilization in seasons without heating.

[0060] The heat pump 18 is connected to the condensate water heat exchanger 19 for heat exchange with the boiler condensate water pipe, so as to realize waste heat utilization in seasons without heating.

[0061] The primary vacuum pump 14 and the secondary vacuum pump 16 are connected to the atmosphere through the total vapor-liquid separator 17; the total vapor-liquid separator 17 is arranged to prevent the liquid droplets remaining in the atmosphere from polluting the environment when the ambient temperature is low.

[0062] The negative pressure removal of non-condensable gas coupled with flash evaporation waste heat utilization method based on the device of the present embodiment includes the following processes:

[0063] S1, the desulfurization slurry accumulated in the desulfurization tower 2 enters the primary flash tank 8, and is converted into primary slurry and non-condensable gas; the non-condensable gas and the mist droplets are separated from the primary gas-liquid separator through the cyclone mist removal device 9, and the non-condensable gas is discharged through the primary vacuum pump 14; the primary slurry enters the secondary flash tank 30 through the flow-through device 29, and is converted into secondary slurry and low-temperature steam; the low-temperature steam enters the heat pump 18 to release latent heat, and the secondary slurry returns to the desulfurization tower 2; the condensate water formed after the low-temperature steam releases latent heat is supplemented into the auxiliary heating pipe or the heat network pipe.

[0064] S2, the heat exchanger 1 absorbs the heat of the original flue gas entering the desulfurization tower 2 to heat the circulating medium; the circulating medium is input into the heat pump 18 as the driving heat source of the heat pump 18; when the heat exchanger 1 is insufficient in heat, the steam auxiliary heater 26 is started to heat the circulating medium.

[0065] S3, the heat pump 18 realizes heating through the heat supply pipe network.

[0066] The above only describes the preferred embodiments of the present application and is not used to limit the present application; for those skilled in the art, the present application can have various modifications and changes; any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A device for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization, characterized in that, It includes a heat exchanger, a desulfurization tower, a flash evaporation device, and a heat pump connected in sequence; the flash evaporation device includes a primary flash tank and a secondary flash tank connected by a flow passage device; the heat exchanger and the heat pump are connected through an auxiliary heater; the heat pump is connected to a heating network. The primary flash tank includes a primary slurry tank, which is connected to a secondary flash tank via a flow-through device. The flow passage device includes numerous flow passages with multiple apertures, allowing the slurry in the primary slurry tank to enter the secondary flash tank, and atomizing the slurry in the form of a screen structure; The first-stage flash tank is connected to the first-stage vacuum pump; a first-stage gas-liquid separator is provided between the first-stage flash tank and the first-stage vacuum pump; A large amount of non-condensable gas is released from the slurry in the first-stage flash tank. The first-stage vacuum pump extracts the non-condensable gas and discharges it into the atmosphere. The slurry after the non-condensable gas is removed in the first-stage flash system enters the second-stage flash tank. The slurry in the second-stage flash tank flashes out low-temperature steam under vacuum negative pressure. The first-stage flash tank is equipped with a cyclone demister to remove liquid droplets entrained in the non-condensable gas discharged from the first-stage flash tank. The cyclone demisting device consists of cyclone plates, cyclone outer walls, a cyclone sub-center cylinder, and cyclone sub-partitions. The cyclone sub-center cylinder can rotate around its central axis. Multiple cyclone plates are installed around the periphery of the cyclone sub-center cylinder, and the cyclone plates are surrounded by the cyclone outer walls as fixing devices. The cyclone plates, cyclone outer walls, and cyclone sub-center cylinder form a cyclone, which is installed in a frame composed of multiple cyclone sub-partitions. The cyclone plates of adjacent cyclone sub-partitions are either clockwise or counterclockwise. The secondary flash tank is connected to the secondary vacuum pump via the heat pump; a secondary gas-liquid separator is provided between the heat pump and the secondary vacuum pump.

2. The apparatus for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 1, characterized in that, The slurry outlet of the desulfurization tower is connected to the flash spray layer of the primary flash tank; the secondary flash tank includes a secondary slurry pool, which is connected to the slurry spray device of the desulfurization tower.

3. The apparatus for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 1, characterized in that, The auxiliary heater is a steam-assisted heater, which is connected to an external source of steam.

4. The apparatus for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 1, characterized in that, The heat pump is connected to the heating network.

5. The apparatus for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 4, characterized in that, The heat pump is connected to the heater heat exchanger.

6. The apparatus for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 4, characterized in that, The heat pump is connected to a condensate heat exchanger.

7. A method for utilizing the waste heat from non-condensable gases coupled with flash evaporation, based on the apparatus for negative pressure removal of non-condensable gases according to any one of claims 1-6, characterized in that, The process includes the following: S1. The desulfurization slurry accumulated in the desulfurization tower enters the first-stage flash tank and is converted into first-stage slurry and non-condensable gas. The first-stage slurry enters the second-stage flash tank through the flow-through device and is converted into second-stage slurry and low-temperature steam. The low-temperature steam enters the heat pump to release latent heat, and the second-stage slurry is returned to the desulfurization tower. S2. The heat exchanger absorbs the heat from the raw flue gas entering the desulfurization tower to heat the circulating medium, and the circulating medium is input into the heat pump as the driving heat source of the heat pump. S3. The heat pump provides heating through a heating network.

8. The method for negative pressure removal of non-condensable gases coupled with flash evaporation waste heat utilization as described in claim 7, characterized in that, In S1, the condensate formed after the low-temperature steam releases its latent heat is added to the auxiliary heating pipeline or the heating network pipeline.

9. The method for removing non-condensable gases under negative pressure and coupling flash evaporation waste heat utilization as described in claim 7, characterized in that, When the heat exchanger in S2 is insufficient, the auxiliary heater is activated to heat the circulating medium.

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