Desulfurization slurry flash evaporation MVR heat pump type flue gas deep waste heat recovery system

Abstract

The utility model discloses a desulfurization slurry flash evaporation MVR heat pump type flue gas deep waste heat recovery system, and belongs to the technical field of coal-fired boiler waste heat heat supply. In view of the fact that a large amount of non-condensable gas such as SO2 can be generated during desulfurization slurry flash evaporation, and high vacuum degree is difficult to maintain by conventional vacuum-pumping equipment and processes, the MVR compressor is adopted to recompress desulfurization slurry flash steam so as to improve steam pressure and energy grade. Desulfurization slurry can be subjected to one-stage or multi-stage flash evaporation, the front flash evaporation tank is used for carrying out negative pressure flash evaporation, and flash evaporation steam enters the front heater to carry out first-stage preheating on heat supply network return water; flash steam of the MVR flash tank is compressed through MVR, the steam pressure and temperature are increased, then the compressed flash steam is fed into the MVR heater to conduct MVR heating on heat supply network return water, and the outlet water temperature of heated water can be greatly increased. And non-condensable gas on the liquid level of condensed water of the front heater is fed into the MVR compressor so as to keep the required vacuum degree. And non-condensable gas of the MVR heater is pumped out by a conventional vacuum pump and sent to an inlet of the original desulfurization tower.

Description

Technical Field

[0001] The utility model relates to a desulfurized slurry flash evaporation MVR heat pump type flue gas deep waste heat recovery system, belonging to the technical field of waste heat heating of coal-fired boilers. Background Technique

[0002] A large amount of high-temperature flue gas is discharged during the heat production process of a boiler. Recycling the waste heat of the flue gas can not only reduce the heat loss of the boiler, but also reduce the fuel consumption and pollutant emissions such as greenhouse gases, and improve the thermal efficiency of the boiler. The existing flue gas waste heat recovery systems mainly include three categories: (1) The first category is to use a shell-and-tube heat exchanger to realize the waste heat recovery of the flue gas, that is, to use a low-temperature economizer or an economizer, etc. An exchanger with a tubular structure or the like is installed on the outlet flue of the boiler to recover the waste heat of the flue gas and heat the boiler feed water or the heating return water. This method has a simple system and a relatively low total cost. The disadvantage is that the waste heat recovery rate is low, and it is affected by the changes in the inlet temperature of the heated water, the flue gas temperature, etc. Usually, the actual temperature difference is only about 20-30°C, which is about 1%-2% of the boiler heat output. The latent heat of vaporization of the water vapor contained in the flue gas cannot be recovered, so deep heat recovery cannot be achieved. (2) The second category is to use the absorption heat pump flue gas deep recovery technology. The absorption heat pump is used to recover the waste heat of the flue gas and heat the network return water, etc. The flue gas temperature can be greatly reduced to about 30°C, and the waste heat recovery amount is equivalent to 8%-15% of the boiler heat output. Therefore, deep heat recovery can be achieved. However, the absorption heat pump needs to consume high-level heat sources such as steam to drive, and a large amount of acidic condensate will be generated in the flue gas, and an anti-corrosion heat exchanger needs to be used, and the equipment investment is relatively high. (3) The third category is the total heat exchange recovery technology based on air-flue gas. By humidifying the air, the dew point temperature of the flue gas is increased, and the condensation heat of the flue gas is recovered in the tail flue. This method has a simple system structure, does not require an additional driving heat source, and has a low investment cost. In recent years, the "steam-carrying boiler flue gas waste heat recovery" series of patented technologies jointly developed by Tsinghua University and Beijing Qingda Tiangong Energy Technology Research Institute (patent numbers CN104110675B, CN107166420A, CN206929794U, etc.) have been widely promoted and applied at present and have good application prospects. However, usually, the atmospheric pressure flue gas waste heat spray tower takes heat from the flue gas by MVR, and the size of the flue gas waste heat spray tower is very large, and a certain resistance will be increased on the flue gas side. If the outlet pressure margin of the original induced draft fan is insufficient, the fan needs to be replaced or a booster induced draft fan needs to be set up. The above situations will all cause an increase in cost, and sometimes the site does not have the implementation conditions.

[0003] In recent years, in the second type of flue gas waste heat recovery method, a method of using desulfurized slurry flash evaporation + absorption heat pump has emerged. That is, the flue gas waste heat exchanger is abandoned, and the heat in the flue gas is taken out from the desulfurized slurry through a flash tank, and the flash steam is sent to the heat pump for waste heat recovery, and the return water of the heat network or other process water is heated, while the concentrated liquid returns to the desulfurized circulating water. Its advantages are: there is no need to transform the flue gas system, reducing the on-site implementation difficulty; the quality of the condensate water is good, which is convenient for recycling. However, the disadvantages are also very obvious: the flue gas temperature can usually only be reduced to 42 - 45°C, recovering about half of the flue gas waste heat, which does not belong to deep heat recovery and can only be regarded as a half-finished project. There is still a large amount of flue gas waste heat escaping from the flue gas, and secondary transformation is still required in the future to achieve deep heat recovery. The cost calculated for the unit waste heat recovery amount is relatively high, and the investment payback period is long. The fundamental reason why it cannot reduce the flue gas temperature to the 30°C level and achieve deep heat recovery is: First, the desulfurized slurry flash evaporation complete set of equipment is a vacuum equipment, its system integration is relatively complex, the guarantee requirements are high, and the lower the flash steam temperature, the larger the specific volume, the larger the equipment volume, and the higher the cost; Second, a large amount of non-condensable gases such as SO2 will escape during the desulfurized slurry flash evaporation process. The flash steam is sent to the absorption heat pump, and it is difficult to evacuate during the condensation and heat release process in the horizontal evaporator of the heat pump. The absolute pressure during actual operation can only be maintained at about 7 - 8 kPa. It is very difficult to further improve the vacuum degree with the existing equipment and conditions, and it is impossible to further improve the vacuum degree like a normal condenser. Therefore, the saturation temperature of the flash steam can only be reduced to the 38 - 40°C level, resulting in the flue gas temperature can only be reduced to the 40 - 45°C level; Third, this technical method still belongs to the heat pump method in essence, only the heat extraction device is different, and a large amount of driving steam is still required, with high operating costs, deteriorating the thermal power flexibility adjustment problem of the power plant, and even sometimes seriously affecting the technical and economic benefits of the power plant. Utility Model Content

[0004] The purpose and task of the present utility model are, aiming at the respective inherent technical limitations of the above-mentioned various flue gas waste heat recovery systems and their impacts on the economy of the power plant, using an MVR compressor to recompress the flash steam, increasing the pressure and temperature of the flash steam and then heating the return water of the heat network to achieve deep waste heat recovery of the flue gas, with a higher energy efficiency ratio and lower operating cost of the waste heat recovery system.

[0005] The specific description of the present utility model is: A desulfurized slurry flash evaporation MVR heat pump type flue gas deep waste heat recovery system, which consists of an original desulfurization tower system and a desulfurized slurry flash evaporation and MVR heat pump subsystem. The original desulfurization tower system includes an original desulfurization tower 1, an original flue gas inlet pipe 2, and an original slurry pump 3. It is characterized in that the desulfurized slurry flash evaporation and MVR heat pump subsystem includes a pre-flash tank 21, a pre-heater 26, a vacuum pump 18, an MVR flash tank 31, an MVR heater 36, an MVR compressor 48, a power machine 49, and connecting pipelines and components. Among them, the slurry inlet of the pre-flash tank 21 is connected to the waste heat slurry outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 through a waste heat slurry pump 10, and the primary concentrated slurry outlet of the pre-flash tank 21 is connected to the slurry inlet of the MVR flash tank 31. The MVR concentrated slurry outlet of the MVR flash tank 31 is connected to the inlet of the original slurry pump 3. Inside the upper part of the pre-flash tank 21, there is a pre-flash steam demister 22 and a pre-washing spray layer 23. Its flash steam outlet is connected to the steam inlet of the pre-heater 26 through a pre-connection pipe 25. The condensate outlet of the pre-heater 26 is connected to the inlet of a pre-condensate pump 27. The outlet of the pre-condensate pump 27 is communicated with the inlet of the pre-washing spray layer 23 and the outlet pipe of the pre-external discharged condensate W1. Inside the upper part of the MVR flash tank 31, there is a flash steam MVR demister 32 and an MVR washing spray layer 33. Its flash steam outlet is connected to the steam inlet of the MVR compressor 48 through an MVR connection pipe 35. The steam outlet of the MVR compressor 48 is connected to the steam inlet of the MVR heater 36. The power input connection device of the MVR compressor 48 is connected to the power output connection device of the power machine 49. The condensate outlet of the MVR heater 36 is connected to the inlet of an MVR condensate pump 37. The outlet of the MVR condensate pump 37 is respectively communicated with the inlet of the MVR washing spray layer 33 and the outlet pipe of the MVR external discharged condensate W2. The low-temperature water inlet of the pre-heater 26 is communicated with the incoming water pipe of the heat network return water H1. The low-temperature water outlet of the pre-heater 26 is connected to the low-temperature water inlet of the MVR heater 36. The low-temperature water outlet of the MVR heater 36 is connected to the return water pipe of the heat network return water H2. The outlet of the pre-non-condensable gas S of the pre-heater 26 is connected to the steam inlet of the MVR compressor 48 through a non-condensable gas regulating valve 29. The outlet of the MVR non-condensable gas S2 of the MVR heater 36 is connected to the air inlet of the vacuum pump 18. The exhaust outlet of the vacuum pump 18 is communicated with the original flue gas inlet pipe 2 of the original desulfurization tower 1. The upstream of the original flue gas inlet pipe 2 is the inlet of the original flue gas Y1 from the boiler outlet, and the downstream is the flue gas inlet of the original desulfurization tower 1. The top of the original desulfurization tower 1 is the outlet of the clean flue gas Y2.The circulating liquid outlets of the bottom desulfurization slurry pool of the original desulfurization tower 1 are respectively communicated with the inlets of the original slurry pump 3, the water inlet pipe of desulfurization make-up water B, and the MVR concentrated slurry outlet of the MVR flash evaporation tank 31. The outlet of the original slurry pump 3 is connected to the circulating slurry inlet of the original desulfurization tower 1. The blowdown outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 is communicated with the drain pipe of desulfurization wastewater P.;

[0006] The desulfurization slurry flash evaporation and MVR heat pump subsystem does not set up a pre-flash evaporation process section, but only sets up an MVR flash evaporation process section, that is, it does not set up a pre-flash evaporation tank 21, a pre-heater 26, and the connecting pipelines and components. The slurry inlet of the MVR flash evaporation tank 31 is connected to the waste heat slurry outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 through the waste heat slurry pump 10; the low-temperature water inlet of the MVR heater 36 is communicated with the water inlet pipe of the return water H1 from the heat network, and the low-temperature water outlet of the MVR heater 36 is communicated with the drain pipe of the return water H2 of the heat network return water.

[0007] The pre-heater 26 and the MVR heater 36 respectively adopt a vertical tube heat exchange structure, with a condensate hot well arranged at the bottom, and a non-condensable gas discharge port arranged above the liquid level of the hot well.

[0008] The interior of the pre-flash evaporation tank 21 is set as a first-stage flash evaporation heat exchange area or an N-stage flash evaporation heat exchange area, where N is greater than or equal to 2. When setting the N-stage heat exchange area, the flash evaporation concentrated slurry outlet of each stage of the heat exchange area is connected to the slurry inlet of its next stage, and the low-temperature water inlet is connected to the low-temperature water outlet of its next stage.

[0009] The MVR compressor 48 adopts a Roots compressor, a centrifugal compressor or an axial flow fan structure.

[0010] The power machine 49 adopts a motor structure, and a frequency converter is provided or not provided for the motor.

[0011] The power machine 49 adopts a driving steam turbine structure, and a speed control device is provided for the driving steam turbine.

[0012] The vacuum pump 18 adopts a water ring vacuum pump, a water jet air ejector or a Roots vacuum pump structure.

[0013] The outlet pipe of the MVR external discharged condensate W2 is respectively communicated with the make-up water inlet pipes of desulfurization make-up water B, the return water H1 from the heat network, and / or the outlet pipe of the pre-external discharged condensate W1.

[0014] The beneficial effects of the present utility model are as follows.

[0015] (1)Recover heat from the desulfurization slurry without adding a flue gas waste heat exchanger and its flue gas resistance; perform single-stage or staged flash evaporation on the desulfurization slurry, and the heated water is also heated in a single-stage or staged countercurrent manner, so as to recover the flue gas waste heat to the greatest extent and reduce the flue gas temperature as much as possible, fundamentally avoiding the inherent disadvantages of the existing desulfurization slurry flash evaporation + absorption heat pump technology method. The maximum waste heat recovery can reach 2 to 3 times.

[0016] (2)Maximally adopt the direct heat exchange method to recover the desulfurization slurry waste heat. The flash steam with lower pressure and temperature generated by the pre-flash tank first performs primary heating on the return water of the heat network; the flash steam with even lower temperature generated by the MVR flash tank can be re-compressed by the MVR compressor and then used for secondary heating of the return water of the heat network. Thus, deep flue gas waste heat recovery is achieved.

[0017] (3)When the driving power machine 49 of the MVR compressor 48 adopts a drag steam turbine structure, its steam consumption is small. The steam consumption per 1 MW of waste heat recovery is only a fraction of that of the absorption heat pump, and its system energy efficiency ratio can reach 2 to 20 (depending on factors such as operating conditions). In contrast, the energy efficiency ratio of the absorption heat pump is usually only about 1.7.

[0018] (4)When the driving power machine 49 of the MVR compressor 48 adopts an electric motor structure, its power consumption is small, and its system energy efficiency ratio can reach 20 to 70 (depending on factors such as operating conditions). In contrast, the system energy efficiency ratio of the ordinary voltage compressor heat pump is only about 2 to 8 levels.

[0019] (5)The pre-heater 26 and the MVR heater 36 adopt a vertical tube bundle heat exchange structure. Although the non-condensable gas contains a large amount of SO2, etc., a large amount of non-condensable gas can still be pumped out by the vacuum pump 18 and the pressure of the flash tank can be effectively reduced, thereby effectively reducing the flue gas temperature.

[0020] (6)Use the condensate of the flash steam to wash the demister in each flash tank, which can maintain a higher demisting effect and supplement water to the desulfurization slurry to replace a part or all of the original desulfurization make-up water B. The make-up water source of the latter is often wastewater with a very high chloride content. After replacing it with the condensate of the flash steam, it can help significantly reduce the external discharge flow of the desulfurization wastewater P and greatly reduce the secondary pollution and operation and maintenance costs caused by it, and improve the operation effect of the desulfurization system.

[0021] (7)The condensate of the flash steam can also be used as the make-up water for the return water of the heat network, which helps to significantly reduce the water production volume and cost of softened water; at the same time, the comprehensive recycling and utilization of the condensate also correspondingly greatly reduces the consumption of water resources.

[0022] (8) This solution and system can be widely applied to the flue gas waste heat recovery heating system of thermal power plants and boiler houses, promoting the realization of comprehensive technical and economic benefits of energy conservation and environmental protection integration. Description of the Drawings

[0023] Figure 1 , 2 is the system schematic diagram of the present utility model.

[0024] Figure 1 , 2 The numbers and names of each component in are as follows.

[0025] Original desulfurization tower 1, original flue gas inlet pipe 2, original slurry pump 3, waste heat slurry pump 10, vacuum pump 18, pre - flash tank 21, flash steam pre - demister 22, pre - washing spray layer 23, pre - connecting pipe 25, pre - heater 26, pre - condensate pump 27, non - condensable gas regulating valve 29, MVR flash tank 31, flash steam MVR demister 32, MVR washing spray layer 33, MVR connecting pipe 35, MVR heater 36, MVR condensate pump 37, MVR compressor 48, power machine 49, desulfurization make - up water B, return water from heat network H1, return water drainage from heat network H2, desulfurization wastewater P, pre - non - condensable gas S, MVR non - condensable gas S2, pre - discharged condensate water W1, MVR discharged condensate water W2, original flue gas Y1, clean flue gas Y2. Specific Embodiments

[0026] Figure 1 , 2 are the system schematic diagram and embodiments of the present utility model.

[0027] The specific embodiments of the present utility model are as follows.

[0028] Specific description of Embodiment 1 of the present utility model: A desulfurized slurry flash evaporation MVR heat pump type flue gas deep waste heat recovery system is composed of an original desulfurization tower system and a desulfurized slurry flash evaporation and MVR heat pump subsystem. The original desulfurization tower system includes an original desulfurization tower 1, an original flue gas inlet pipe 2, and an original slurry pump 3. It is characterized in that the desulfurized slurry flash evaporation and MVR heat pump subsystem includes a pre-flash evaporation tank 21, a pre-heater 26, a vacuum pump 18, an MVR flash evaporation tank 31, an MVR heater 36, an MVR compressor 48, a power machine 49, and connecting pipelines and components. Among them, the slurry inlet of the pre-flash evaporation tank 21 is connected to the waste heat slurry outlet of the bottom desulfurization slurry tank of the original desulfurization tower 1 through a waste heat slurry pump 10, and the primary concentrated slurry outlet of the pre-flash evaporation tank 21 is connected to the slurry inlet of the MVR flash evaporation tank 31. The MVR concentrated slurry outlet of the MVR flash evaporation tank 31 is connected to the inlet of the original slurry pump 3; a flash steam pre-demister 22 and a pre-washing spray layer 23 are arranged in the upper part inside the pre-flash evaporation tank 21. Its flash steam outlet is connected to the steam inlet of the pre-heater 26 through a pre-connection pipe 25. The condensate outlet of the pre-heater 26 is connected to the inlet of a pre-condensate pump 27. The outlet of the pre-condensate pump 27 is communicated with the inlet of the pre-washing spray layer 23 and the outlet pipe of the pre-external discharged condensate W1; a flash steam MVR demister 32 and an MVR washing spray layer 33 are arranged in the upper part inside the MVR flash evaporation tank 31. Its flash steam outlet is connected to the steam inlet of the MVR compressor 48 through an MVR connection pipe 35. The steam outlet of the MVR compressor 48 is connected to the steam inlet of the MVR heater 36. The power input connecting device of the MVR compressor 48 is connected to the power output connecting device of the power machine 49; the condensate outlet of the MVR heater 36 is connected to the inlet of an MVR condensate pump 37. The outlet of the MVR condensate pump 37 is respectively communicated with the inlet of the MVR washing spray layer 33 and the outlet pipe of the MVR external discharged condensate W2; the low-temperature water inlet of the pre-heater 26 is communicated with the incoming water pipe of the return water from the heat network H1. The low-temperature water outlet of the pre-heater 26 is connected to the low-temperature water inlet of the MVR heater 36. The low-temperature water outlet of the MVR heater 36 is communicated with the return water pipe of the return water from the heat network H2; the outlet of the pre-non-condensable gas S of the pre-heater 26 is connected to the steam inlet of the MVR compressor 48 through a non-condensable gas regulating valve 29. The outlet of the MVR non-condensable gas S2 of the MVR heater 36 is connected to the air inlet of the vacuum pump 18. The exhaust outlet of the vacuum pump 18 is communicated with the original flue gas inlet pipe 2 of the original desulfurization tower 1; the upstream of the original flue gas inlet pipe 2 is the inlet of the original flue gas Y1 from the boiler outlet, and the downstream is the flue gas inlet of the original desulfurization tower 1. The top of the original desulfurization tower 1 is the outlet of the clean flue gas Y2;The circulating liquid outlets of the bottom desulfurization slurry pool of the original desulfurization tower 1 are respectively communicated with the inlets of the original slurry pump 3, the water inlet pipe of desulfurization make-up water B, and the MVR concentrated slurry outlet of the MVR flash tank 31. The outlet of the original slurry pump 3 is connected to the circulating slurry inlet of the original desulfurization tower 1. The sewage outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 is communicated with the drain pipe of desulfurization wastewater P.;

[0029] The preheater 26 and the MVR heater 36 respectively adopt a vertical tube heat exchange structure, with a condensate hot well provided at the bottom, and a non-condensable gas discharge port provided above the liquid level of the hot well.

[0030] The interior of the pre-flash tank 21 is set as a primary flash heat exchange zone or an N-stage flash heat exchange zone, where N is greater than or equal to 2. When an N-stage heat exchange zone is set, the flash concentrated slurry outlet of each stage of the heat exchange zone is connected to the slurry inlet of its next stage, and the low-temperature water inlet is connected to the low-temperature water outlet of its next stage.

[0031] The MVR compressor 48 adopts a Roots compressor, a centrifugal compressor or an axial flow fan structure.

[0032] The power unit 49 adopts a motor structure, and a frequency converter is provided or not provided for the motor.

[0033] The power unit 49 adopts a driving steam turbine structure, and a speed control device is provided for the driving steam turbine.

[0034] The vacuum pump 18 adopts a water ring vacuum pump, a jet steam extractor or a Roots vacuum pump structure.

[0035] The outlet pipe of the MVR external discharged condensate W2 is respectively communicated with the desulfurization make-up water B, the make-up water inlet pipe of the return water of the heat supply network H1 and / or the outlet pipe of the pre-external discharged condensate W1.

[0036] Specific description of the second embodiment of the present utility model: The desulfurization slurry flash and MVR heat pump subsystem do not set a pre-flash process section, but only set an MVR flash process section, that is, the pre-flash tank 21, the preheater 26 and the connecting pipelines and components are not set. The slurry inlet of the MVR flash tank 31 is connected to the waste heat slurry outlet of the bottom desulfurization slurry pool of the original desulfurization tower 1 through the waste heat slurry pump 10; the low-temperature water inlet of the MVR heater 36 is communicated with the incoming water pipe of the return water of the heat supply network H1, and the low-temperature water outlet of the MVR heater 36 is communicated with the drain pipe of the return water of the heat supply network H2. The rest of the second embodiment is the same as the first embodiment.

[0037] It should be noted that the present utility model is based on key technologies such as single-stage or multi-stage flashing technology of desulfurization slurry, adoption of MVR heat pump technology, and use of clean condensate water as desulfurization make-up water to reduce the discharge flow of desulfurization wastewater, etc. A complete set of new integrated systems and operation strategies for flashing desulfurization slurry + boosting pressure and temperature by MVR compressor to recover flue gas waste heat in depth are proposed. According to this overall solution, there can be different specific implementation measures and specific implementation devices with different structures. The above specific implementation manners are just one of them. Any other similar simple deformed implementation manners, such as changing the type, number of stages, and combination mode of the compressor, simple deformation of the flash steam and heat exchanger, and simple adjustment of the relevant pipelines, etc., or simple changes in the vacuum pumping method, condensate water recovery and utilization method, etc., all fall within the protection scope of the present utility model.

Claims

1. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system, consisting of an original desulfurization tower system and a desulfurization slurry flash and MVR heat pump subsystem, wherein the original desulfurization tower system comprises an original desulfurization tower (1), an original flue gas inlet pipe (2) and an original slurry pump (3), characterized in that: The desulfurization slurry flash and MVR heat pump subsystem comprises a pre-flash tank (21), a pre-heater (26), a vacuum pump (18), an MVR flash tank (31), an MVR heater (36), an MVR compressor (48), a power machine (49) and connecting pipelines and components, wherein the slurry inlet of the pre-flash tank (21) is connected to the waste heat slurry outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) via a waste heat slurry pump (10), and the primary concentrated slurry outlet of the pre-flash tank (21) is connected to the slurry inlet of the MVR flash tank (31), and the MVR concentrated slurry outlet of the MVR flash tank (31) is connected to the inlet of the original slurry pump (3); the pre-flash tank (21) is connected to the pre-heated slurry outlet of the MVR flash tank (31), and the MVR concentrated slurry outlet of the MVR flash tank (31) is connected to the inlet of the original slurry pump (3); A flash steam pre-mist demister (22) and a pre-washing spray layer (23) are provided at the upper part of the interior of the tank (21), and the flash steam outlet is connected to the steam inlet of the pre-heater (26) through a pre-connecting pipe (25), the condensate outlet of the pre-heater (26) is connected to the inlet of the pre-condensate pump (27), and the outlet of the pre-condensate pump (27) is connected to the inlet of the pre-washing spray layer (23) and the outlet pipe of the pre-exhaust condensate (W1); a flash steam MVR demister (32) and an MVR washing spray layer (33) are provided at the upper part of the interior of the MVR flash tank (31), and the flash steam outlet is connected to the steam inlet of the MVR compressor (48) through an MVR connecting pipe (35). The steam outlet of the MVR compressor (48) is connected to the steam inlet of the MVR heater (36), and the power input connection device of the MVR compressor (48) is connected to the power output connection device of the power machine (49); the condensate outlet of the MVR heater (36) is connected to the inlet of the MVR condensate pump (37), and the outlet of the MVR condensate pump (37) is respectively connected to the inlet of the MVR washing spray layer (33) and the outlet pipe of the MVR condensate (W2) discharged externally; the low-temperature water inlet of the pre-heater (26) is connected to the water pipe of the return water (H1) of the heating network, and the low-temperature water outlet of the pre-heater (26) is connected to the low-temperature water inlet of the MVR heater (36). The low-temperature water outlet of the VR heater (36) is connected to the return water (H2) return water pipe of the heat network; the outlet of the pre-heater (26) non-condensable gas (S) is connected to the steam inlet of the MVR compressor (48) via the non-condensable gas regulating valve (29); the outlet of the MVR non-condensable gas (S2) of the MVR heater (36) is connected to the air inlet of the vacuum pump (18); the exhaust port of the vacuum pump (18) is connected to the original flue gas inlet pipe (2) of the original desulfurization tower (1); the upstream of the original flue gas inlet pipe (2) is the inlet of the original flue gas (Y1) from the boiler outlet, the downstream is the flue gas inlet of the original desulfurization tower (1), and the top of the original desulfurization tower (1) is the outlet of the clean flue gas (Y2);The circulating liquid outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) is respectively connected to the inlet of the original slurry pump (3), the water inlet pipe of the desulfurization makeup water (B) and the MVR concentrated slurry outlet of the MVR flash tank (31), the outlet of the original slurry pump (3) is connected to the circulating slurry inlet of the original desulfurization tower (1), and the sewage outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) is connected to the drainage pipe of the desulfurization wastewater (P). ; 2. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The desulfurization slurry flash evaporation and MVR heat pump subsystem is not provided with a pre-flash evaporation process section, but only with an MVR flash evaporation process section, that is, a pre-flash tank (21) and a pre-heater (26) and connecting pipelines and components are not provided, wherein the slurry inlet of the MVR flash tank (31) is connected to the waste heat slurry outlet of the desulfurization slurry pool at the bottom of the original desulfurization tower (1) through a waste heat slurry pump (10); the low-temperature water inlet of the MVR heater (36) is connected to the water inlet pipe of the heat network return water (H1), and the low-temperature water outlet of the MVR heater (36) is connected to the water return pipe of the heat network return water (H2).

3. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The preheater (26) and the MVR heater (36) respectively adopt a vertical tube-in-tube heat exchange structure, a condensate hot well is provided at the bottom, and a non-condensable gas discharge port is provided above the hot well liquid surface.

4. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The interior of the pre-flash tank (21) is configured as a first-stage flash heat exchange zone or an N-stage flash heat exchange zone, wherein N is greater than or equal to 2. When N-stage heat exchange zones are configured, the flash concentrated slurry outlet of each stage heat exchange zone is connected to the slurry inlet of the next stage heat exchange zone, and the low-temperature water inlet is connected to the low-temperature water outlet of the next stage heat exchange zone.

5. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The MVR compressor (48) adopts a Roots compressor, a centrifugal compressor or an axial flow fan structure.

6. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The power machine (49) adopts an electric motor structure, wherein the electric motor is equipped with or without a frequency converter.

7. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The power machine (49) adopts a drag steam turbine structure, wherein the drag steam turbine is equipped with a speed control device.

8. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The vacuum pump (18) adopts a water ring vacuum pump, a water jet steam extractor or a Roots vacuum pump structure.

9. A desulfurization slurry flash MVR heat pump flue gas deep waste heat recovery system as claimed in claim 1, characterized in that The outlet pipe of the MVR external condensate water (W2) is respectively connected to the feed water pipe inlet of the desulfurization feed water (B), the heat network return water (H1) and / or the outlet pipe of the front external condensate water (W1).

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