WO2016082430A1 - Plate-type multi-stage flash distillation apparatus for desulfurization wastewater treatment and recovery and method therefor - Google Patents

Abstract

Provided are a plate-type multi-stage flash distillation apparatus for desulfurization wastewater treatment and recovery and a method therefor. The apparatus is mainly composed of plate-type heat exchangers, a plate-type condenser (12), a boiler (29), flash distillation tanks, freshwater tanks, water pumps and stainless steel pipelines. A pretreated desulfurization wastewater is brought into the plate-type heat exchanger stage by stage, heated to a certain temperature, and then brought into a first stage flash distillation tank (5) for flash distillation, the secondary steam is brought into the next-stage plate-type heat exchangers and condensed to release the latent heat to preheat the desulfurization wastewater, the concentrated desulfurization wastewater is brought into the next-stage flash distillation tank for flash distillation, and the process is carried out in sequence to the final stage, in which the secondary steam is brought into the plate-type condenser (12), the condensed fresh water in each stage is brought into a freshwater pool (17) for recycling, a part of the concentrated desulfurization wastewater is used as a circulating liquid to maintain the continuous proceeding of the flash distillation process, and a part thereof is brought into a concentrated liquid treating pool (19) and subjected to a centralized treatment. The apparatus and method can recover the latent heat of the secondary steam, has a high concentration multiple, a small occupation area and a low energy consumption, and can achieve zero release of the desulfurization wastewater.

Description

Plate type multi-stage flash desulfurization wastewater treatment and recovery device and method thereof Technical field

The invention relates to a plate type multi-stage flash desulfurization wastewater treatment and recovery device and a method thereof, and belongs to the technical field of desulfurization wastewater treatment.

Background technique

The SO ₂ emitted from coal-fired power plants will cause serious air pollution, and the desulfurization system must be installed to remove SO ₂ . There are many desulfurization technologies in thermal power plants. According to the different positions of the process in the combustion process, it can be divided into desulfurization before combustion, desulfurization in combustion and desulfurization after combustion. The first two desulfurization technologies have not been widely used due to economic factors and unit capacity limitations. Desulfurization after combustion, ie flue gas desulfurization (FGD), is currently the only desulfurization technology for large-scale commercial operation. Among all flue gas desulfurization technologies, limestone-gypsum flue gas desulfurization is the most widely used desulfurization technology, accounting for more than 80% of the total installed capacity.

When the limestone-gypsum flue gas is desulfurized, the slurry in the desulfurization absorption tower is repeatedly recycled, and in the process, the slurry soluble salt is continuously concentrated. In order to maintain the desulfurization performance of the system, the slurry needs to be continuously replenished and renewed, and the wastewater containing a large amount of heavy metal ions needs to be discharged. This part of the discharged wastewater is called desulfurization wastewater. The desulfurization wastewater is acidic, containing a large amount of suspended solids, metal ions and anions such as S0 ₄ ^2‐ , Cl ^‐ and F ^‐ and traces of heavy metal ions, which cannot be directly discharged.

The conventional desulfurization wastewater treatment method is complicated, requires many physical and chemical reactions, consumes a large amount of chemicals, has high cost, and the wastewater cannot be recycled. The desulfurization wastewater is concentrated and concentrated by evaporation to achieve "zero discharge" of the desulfurization wastewater. At present, the factors restricting the development of thermal evaporation desulfurization wastewater treatment technology are mainly the serious corrosion scale in the evaporator. Therefore, it is necessary to develop a new treatment method for desulfurization wastewater to solve the problem of corrosion and scaling in the evaporator.

Summary of the invention

The invention aims to overcome the deficiencies of the existing desulfurization wastewater treatment technology, and to provide a multi-stage flash desulfurization wastewater treatment and recovery capable of effectively avoiding corrosion and scaling, realizing zero discharge of desulfurization wastewater, small floor space and low steam consumption. Apparatus and method therefor.

The plate type multi-stage flash desulfurization wastewater treatment and recovery device comprises a first-stage plate heat exchanger, a first-stage booster pump, a second-stage plate heat exchanger, a second-stage booster pump, a first-stage fresh water tank, and a nth ‐1 plate heat exchanger, n-1 stage booster pump, second stage fresh water tank, nth grade plate heat exchanger, nth stage booster pump, n-1st fresh water tank, plate condenser, Desulfurization wastewater pretreatment tank, booster pump, nth grade fresh water tank, fresh water pump, fresh water tank, circulating water pump, concentrate treatment tank, nth stage Pump, three-way valve, n-stage flash tank, n-th grade pump, n-th grade flash tank, second stage pump, second stage flash tank, first stage pump, First stage flash tank, boiler;

The first stage plate heat exchanger steam inlet is connected to the boiler steam outlet through a pipeline, and the condensed water outlet is connected to the boiler water inlet through a pipeline, and the desulfurization waste water inlet is connected to the first stage booster pump outlet through a pipeline, and the desulfurization waste water outlet passes through The pipeline is connected to the first stage flash tank desulfurization wastewater inlet;

The steam inlet of the second-stage plate heat exchanger is connected to the secondary steam outlet of the first-stage flash tank through a pipeline, and the condensed water outlet is connected to the first-stage fresh water tank through the pipeline, and the desulfurization wastewater inlet is passed through the pipeline and the second-stage liter The pressure pump outlet is connected, and the desulfurization waste water outlet is connected to the inlet of the first stage booster pump through a pipeline;

The steam inlet of the n-th grade plate heat exchanger is connected to the secondary steam outlet of the n-th stage flash tank through a pipeline, and the condensed water outlet is connected to the n-th grade fresh water tank through the pipeline, and the desulfurization waste water inlet is passed through The pipeline is connected to the outlet of the n-1st stage booster pump, and the outlet of the desulfurization waste water is connected to the inlet of the nth-stage booster pump through a pipeline;

The steam inlet of the nth plate heat exchanger is connected to the secondary steam outlet of the n-1th flash tank through a pipeline, and the condensate outlet is connected to the n-1th fresh water tank through a pipeline, and the desulfurization waste water is imported through the pipeline. The outlet of the nth stage booster pump is connected, and the outlet of the desulfurization waste water is connected to the inlet of the n-1st stage booster pump through a pipeline;

The steam inlet of the plate condenser is connected to the secondary steam outlet of the nth stage flash tank through a pipeline, and the condensed water outlet is connected to the nth stage fresh water tank through a pipeline, and the inlet of the desulfurization waste water is connected to the outlet of the booster pump through a pipeline, and the desulfurization waste water is discharged. The outlet is connected to the inlet of the nth stage booster pump through a pipe;

The pre-treatment tank for desulfurization wastewater is connected to a plate condenser through a booster pump; the first-stage fresh water tank is connected to the second-stage fresh water tank through a pipeline, and the second-stage fresh water tank is connected to the third-stage fresh water tank through a pipeline. The n-1th fresh water tank is connected to the nth fresh water tank through a pipeline, and the nth fresh water tank is connected to the fresh water tank through a fresh water pump; the first stage flash tank drain port passes the first stage pump and The second-stage flash tank desulfurization wastewater inlet is connected, and the second-stage flash tank drain port is connected to the third-stage flash tank desulfurization wastewater inlet through the second-stage pump, and the n-th-stage flash tank drain port is passed. The n-1st stage pump is connected to the nth stage flash tank desulfurization wastewater inlet, and the nth stage flash tank drain port is connected to the concentrate treatment tank through the nth stage transfer pump; the circulating pump passes through the pipeline and the third Connected to the valve.

The plate heat exchanger is formed by stacking a plurality of plates, the plate includes a positioning hole, a working medium inlet and outlet, a sealing ring, a flow guiding region, a heat exchange region, and a water droplet-shaped concave vortex; Positioning hole, the four corners of the plate are symmetrically connected with the working medium inlet and outlet, and the heat exchange zone is arranged in the middle of the plate. The heat transfer zone is provided with a flow guiding zone on both sides, and the water exchange zone is provided with a drop-shaped concave vortex, the plate A sealing ring is arranged on one side of the diversion zone, the heat exchange zone and the inlet and outlet of the two hot working fluids, and a sealing ring is arranged around the inlet and outlet of the other side of the plate, the heat exchange zone and the inlet and outlet of the two cold working fluids. The length of the drop-shaped depression vortex flow zone is 2R, the depth of the depression is 0.4R, the length of the wake vortex zone is R, the vortex and the vortex are staggered, the vortex spacing in the flow direction is 5R, and the vortex spacing in the direction of the plate width is 4R. The length of the wake vortex region is 4-10 mm.

The flash tank includes a secondary steam outlet, a pressure regulating valve, a defoaming net, a desulfurization waste water inlet, a first baffle, a second baffle, a flange, a screw, a nut, a descaling net, and a liquid discharge port. The scaffold can be divided into upper and lower parts by flanges, screws and nuts. The top of the flash tank is provided with a secondary steam outlet. The upper part of the flash tank is provided with a pressure regulating valve, and the middle part of the flash tank is provided. There is desulfurization wastewater inlet, the bottom of the flash tank is provided with a liquid discharge port and a bracket, and the defoaming net, the first baffle plate, the second baffle plate, the descaling net, the descaling are arranged from top to bottom in the flash tank. The net is fixed in the flash tank by a flange. The defoaming net and the descaling net are made of a wire mesh material.

The plate type multi-stage flash desulfurization wastewater treatment and recovery method is: the booster pump pumps the desulfurization waste water in the desulfurization wastewater pretreatment tank into the plate condenser, and the desulfurization waste water is heated by the secondary steam from the nth stage flash tank. The n-stage booster pump is sent to the nth-stage plate heat exchanger, and the secondary steam is condensed and then enters the n-th stage fresh water tank; the desulfurization waste water in the n-th plate heat exchanger is taken from the n-th grade flash tank After the secondary steam is heated, it is sent to the n-1st plate heat exchanger via the n-1 stage booster pump, and the secondary steam in the nth plate heat exchanger is condensed and then enters the n-1st fresh water tank; The desulfurization wastewater in the 1 grade plate heat exchanger is heated by the secondary steam from the n-th grade flash tank and sent to the n-2 stage plate heat exchanger via the n-2 stage booster pump, nth The secondary steam in the ‐1 plate heat exchanger is condensed and enters the n-th grade fresh water tank; the desulfurization waste water in the second-stage plate heat exchanger is heated by the secondary steam from the first-stage flash tank. The first-stage booster pump is sent to the first-stage plate heat exchanger, and the secondary steam in the second-stage plate heat exchanger is condensed and then enters the first-stage fresh water tank; The desulfurization wastewater in the plate-type heat exchanger is heated by the steam from the boiler and enters the first-stage flash tank. The steam is condensed and sent back to the boiler. The pressure of the first-stage flash tank is adjusted by the pressure regulating valve to cause the desulfurization wastewater to flash. The steaming and desulfurization wastewater sequentially flows through the first baffle plate and the second baffle plate, so that the flashing time is prolonged, the secondary steam enters the second-stage plate heat exchanger, and the concentrated liquid is descaled by the descaling net to be the first stage. The pump is pumped into the second-stage flash tank; the pressure of the second-stage flash tank is adjusted by the pressure regulating valve to cause the desulfurization wastewater to flash, and the desulfurization wastewater flows through the first baffle and the second baffle in turn, so that The flashing time is prolonged, the secondary steam enters the third-stage plate heat exchanger, and the concentrated liquid is descaled by the descaling net and then pumped into the third-stage flash tank by the second-stage pump; the n-1 is adjusted by the pressure regulating valve The pressure of the flash tank causes the desulfurization wastewater to flash, and the desulfurization wastewater flows through the first baffle plate and the second baffle plate in turn, so that the flashing time is prolonged, and the secondary steam enters the nth-stage plate heat exchanger, and is concentrated. After the liquid is descaled by the descaling net, it is pumped into the nth stage flash tank by the n-1th stage pump; The pressure of the nth stage flash tank is adjusted by the pressure regulating valve to flash the desulfurization wastewater, and the desulfurization wastewater flows through the first baffle plate and the second baffle plate in sequence, so that the flashing time is prolonged, and the secondary steam enters the plate condensation. The concentrate is descaled by the descaling net and divided into two by a three-way valve. One way is used as a circulating liquid and pumped into the n-stage plate heat exchanger by the circulating pump to maintain the flashing process, and the other is transported by the nth stage. The pump is pumped into the concentrate treatment tank for centralized treatment; the fresh water in each level of fresh water tank is reclaimed after being sent to the freshwater pool via the fresh water pump.

Compared with the prior art, the present invention has the following advantages:

1. The invention adopts plate heat exchanger combined with multi-stage flashing method to treat desulfurization waste water, can improve heat transfer coefficient, reduce flow resistance, fully recycle secondary steam latent heat, reduce primary steam consumption, and realize zero discharge of desulfurization wastewater. ".

2. The preheating process of the desulfurization wastewater in the present invention occurs in the plate heat exchanger, and the flashing process takes place in the flash tank, which can effectively avoid corrosion and scale formation in the plate heat exchanger.

3. The invention designs a two-stage baffle and a descaling net inside the flash tank. The baffle can extend the flashing process time and improve the flashing effect; the descaling net is fixed by the flange, which is convenient for disassembly and regular replace.

4. The invention adopts multi-stage flashing, which can realize the classification and recycling of the concentrated liquid and the precipitate.

DRAWINGS

Figure 1 is a schematic view showing the structure of a plate type multi-stage flash desulfurization wastewater treatment and recovery device;

Figure 2 is a schematic view showing the structure of a drop-shaped recessed scroll plate of the present invention;

Figure 3 is a geometrical view of the drop-shaped recessed vortex of the present invention;

Figure 4 is a relative position distribution diagram of the drop-shaped recessed vortex of the present invention;

Figure 5 is a schematic view showing the structure of a flash tank of the present invention.

detailed description

As shown in Figures 1, 2, 3, 4 and 5, the plate type multi-stage flash desulfurization wastewater treatment device comprises a first stage plate heat exchanger 1, a first stage booster pump 2, a second stage plate heat exchanger 3, Second stage booster pump 4, first stage fresh water tank 5, n-1st stage plate heat exchanger 6, n-1st stage booster pump 7, second stage fresh water tank 8, nth stage plate heat exchanger 9. The nth stage booster pump 10, the nth 1st fresh water tank 11, the plate condenser 12, the desulfurization wastewater pretreatment tank 13, the booster pump 14, the nth grade fresh water tank 15, the fresh water pump 16, the fresh water tank 17 a circulating water pump 18, a concentrate treatment tank 19, an nth stage transfer pump 20, a three-way valve 21, an nth stage flash tank 22, an n-th stage transfer pump 23, an nth-stage stage flash tank 24, a second stage transfer pump 25, a second stage flash tank 26, a first stage transfer pump 27, a first stage flash tank 28, a boiler 29;

The steam inlet of the first-stage plate heat exchanger 1 is connected to the steam outlet of the boiler 29 through a pipe, and the condensed water outlet is connected to the water inlet of the boiler 29 through a pipe, and the inlet of the desulfurized waste water is connected to the outlet of the first-stage booster pump 2 through a pipe. The desulfurization waste water outlet is connected to the first stage flash tank desulfurization waste water inlet 39 through a pipeline;

The steam inlet of the second-stage plate heat exchanger 3 is connected to the first-stage flash tank secondary steam outlet 36 through a pipeline, and the condensed water outlet is connected to the first-stage fresh water tank 5 through a pipeline, and the desulfurization wastewater inlet is passed through the pipeline and the first The outlet of the secondary booster pump 4 is connected, and the outlet of the desulfurization waste water is connected to the inlet of the first stage booster pump 2 through a pipeline;

The steam inlet of the n-1st plate heat exchanger 6 is connected to the secondary steam outlet 36 of the n-2th flash tank through a pipeline, and the condensate outlet is connected to the n-2th fresh water tank through the pipeline, and the desulfurization wastewater is discharged. The inlet is connected to the outlet of the n-th stage booster pump 7 through a pipeline, and the outlet of the desulfurization waste water is connected to the inlet of the n-th stage booster pump through a pipeline;

The steam inlet of the nth grade plate heat exchanger 9 is connected to the n-th stage flash tank secondary steam outlet 36 through a pipeline, and the condensed water outlet is connected to the n-1st fresh water tank 11 through a pipeline, and the desulfurization waste water inlet is connected. Connected to the outlet of the nth stage booster pump 10 through a pipe, and the desulfurization waste water outlet is connected to the inlet of the n-1st stage booster pump 7 through a pipe;

The steam inlet of the plate condenser 12 is connected to the n-stage flash tank secondary steam outlet 36 through a pipeline, and the condensed water outlet is connected to the n-stage fresh water tank 15 through a pipeline, and the desulfurized waste water inlet is passed through the pipeline and the boost pump 14 outlet. Connected, the desulfurization waste water outlet is connected to the inlet of the nth stage booster pump 10 through a pipeline;

The desulfurization wastewater pretreatment tank 13 is connected to the plate condenser 12 by a booster pump 14; the first stage fresh water tank 5 is connected to the second stage fresh water tank 8 through a pipeline, and the second stage fresh water tank 8 is connected through the pipeline The third stage fresh water tank is connected, the n-1st fresh water tank 11 is connected to the nth fresh water tank 15 through a pipeline, and the nth fresh water tank 15 is connected to the fresh water tank 17 through the fresh water pump 16; the first stage flashing The drain port of the tank 28 is connected to the desulfurization waste water inlet of the second stage flash tank 26 through the first stage transfer pump 27, and the liquid discharge port of the second stage flash tank 26 is desulfurized by the second stage transfer pump 25 and the third stage flash tank. The waste water inlet is connected, and the liquid discharge port of the n-th stage flash tank 24 is connected to the inlet of the desulfurization waste water of the nth stage flash tank 22 through the n-th stage transfer pump 23, and the liquid discharge port of the nth stage flash tank 22 passes through the The n-stage transfer pump 20 is connected to the concentrate treatment tank 19; the circulation pump 18 is connected to the three-way valve 21 through a pipe.

The plate heat exchanger is formed by stacking a plurality of plates, and the plate comprises a positioning hole 30, a working medium inlet and outlet 31, a sealing ring 32, a flow guiding area 33, a heat exchange area 34, and a water drop-shaped concave vortex 35; Locating holes 30 are arranged in the middle of the two sides of the sheet, and the four inlets of the plate are symmetrically provided with the working medium inlet and outlet 31, and the heat exchange zone 34 is arranged in the middle of the plate, and the heat transfer zone 34 is provided with a flow guiding zone 33 on both sides thereof, and heat exchange a water droplet-shaped recessed vortex 35 is arranged in the area 34, a flow guiding area 33 on one side of the sheet, a heat exchange area 34 and two heat working medium inlet and outlet are provided with a sealing ring 32, and a flow guiding area 33 on the other side of the sheet, A sealing ring 32 is arranged around the heat exchange area 34 and the inlet and outlet of the two cold working fluids. The length of the drop-shaped recessed vortex flow area is 2R, the depth of the recess is 0.4R, the length of the tail vortex area is R, and the vortex and the vortex are between Arranged in a staggered arrangement, the vortex pitch is 5R in the flow direction, and the vortex pitch is 4R in the plate width direction. The length of the wake vortex region is 4-10 mm.

The flash tank includes a secondary steam outlet 36, a pressure regulating valve 37, a defoaming net 38, a desulfurization waste water inlet 39, a first baffle 40, a second baffle 41, a flange 42, a screw 43, a nut 44, descaling net 45, liquid discharge port 46, bracket 47; flash tank is divided into upper and lower parts are fixed by flange 42, screw 43, nut 44, the top of the flash tank is provided with a secondary steam outlet 36, flash The upper part of the steaming tank is provided with a pressure regulating valve 37. The middle part of the flash tank is provided with a desulfurization waste water inlet 39. The bottom of the flash tank is provided with a liquid discharge port 46 and a bracket 47. The flash tank is provided with a defoaming from top to bottom. The net 38, the first baffle 40, the second baffle 41, the descaling net 45, and the descaling net 45 are fixed in the flash tank by flanges. The defoaming net 38 and the descaling net 45 are made of a wire mesh material.

The plate type multi-stage flash desulfurization wastewater treatment and recovery method is: the booster pump 14 pumps the desulfurization waste water in the desulfurization wastewater pretreatment tank 13 into the plate condenser 12, and the desulfurization waste water is the secondary steam from the nth stage flash tank 22. After heating, it is sent to the nth stage plate heat exchanger 9 via the nth stage booster pump 10, and the secondary steam is condensed and then enters the nth stage fresh water tank 15; the desulfurization waste water in the nth stage plate heat exchanger 9 is from the nth After the secondary steam of the -1 stage flash tank 24 is heated, it is sent to the n-1st stage plate heat exchanger 6 via the n-1 stage booster pump 7, and the secondary steam in the nth stage plate heat exchanger 9 is condensed. After entering the n-1 level fresh water tank 11; the desulfurization wastewater in the n-1 stage plate heat exchanger 6 is heated by the secondary steam from the n-th stage flash tank and then boosted through the n-2 stage The pump is sent to the n-2 stage plate heat exchanger, and the secondary steam in the n-1st plate heat exchanger 6 is condensed and then enters the n-2 stage fresh water tank; the desulfurization in the second stage plate heat exchanger 3 The wastewater is heated by the secondary steam from the first stage flash tank 28 and sent to the first stage plate heat exchanger 1 via the first stage booster pump 2, and the secondary steam in the second stage plate heat exchanger 3 is condensed. Entering the first stage fresh water tank 5; the desulfurization waste water in the first stage plate heat exchanger 1 is heated by the steam from the boiler 29 and then enters the first stage flash tank 28, and the steam is condensed and sent back to the boiler 29; through the pressure regulating valve 37 Adjusting the pressure of the first stage flash tank 28 to cause the desulfurization waste water to flash, and the desulfurization waste water sequentially flows through the first baffle 40 and the second baffle 41, so that the flashing time is prolonged, and the secondary steam enters the second stage. The plate heat exchanger 3, after the scale is descaled by the descaling net 45, is pumped into the second stage flash tank 26 by the first stage transfer pump 27; the pressure of the second stage flash tank 26 is adjusted by the pressure regulating valve 37. The desulfurization wastewater is flashed, and the desulfurization wastewater flows through the first baffle 40 and the second baffle 41 in sequence, so that the flashing time is prolonged, and the secondary steam enters the first The plate-type heat exchanger, the concentrate is descaled by the descaling net 45 and then pumped into the third-stage flash tank by the second-stage transfer pump 25; the pressure of the n-th-stage flash tank 24 is adjusted by the pressure regulating valve 37, The desulfurization wastewater is flashed, and the desulfurization wastewater flows through the first baffle 40 and the second baffle 41 in sequence, so that the flashing time is prolonged, and the secondary steam enters the nth plate heat exchanger 9, and the concentrated liquid is descaled. After descaling, the net 45 is pumped into the nth stage flash tank 22 by the n-1 stage pump 23; the pressure of the nth stage flash tank 22 is adjusted by the pressure regulating valve 37, so that the desulfurization wastewater is flashed, and the desulfurization wastewater is sequentially Flowing through the first baffle 40 and the second baffle 41, the flashing time is prolonged, the secondary steam enters the plate condenser 12, and the concentrated liquid is descaled by the descaling net 45 and then split into two paths by the three-way valve 21. All the way as the circulating liquid is pumped into the nth stage plate heat exchanger 9 by the circulation pump 18 to maintain the flashing process, and the other path is pumped into the concentrated liquid processing tank 19 by the nth stage transfer pump 20 for centralized treatment; The fresh water in the water is reclaimed into the fresh water tank 17 via the fresh water pump 16 and then recycled.

The invention is illustrated below in conjunction with specific examples, but is not intended to limit the invention in any way.

In this example, the number of stages n is 4, the concentration of imported desulfurization wastewater is 2.5‐4%, the temperature is 40°C, the temperature of the first stage flash tank is 70°C, the temperature difference of each level is 5°C, and the concentration of concentrated liquid is 25%, according to the specific implementation. The equipment and method have the effect that when the heat transfer area per effect is 52m ² , the treated wastewater volume is 100t/d, the fresh water can be recovered 86t/d, and the steam consumption per ton of wastewater is 0.29t.

Claims (6)

A plate type multi-stage flash desulfurization wastewater treatment and recovery device, characterized by comprising a first-stage plate heat exchanger (1), a first-stage booster pump (2), a second-stage plate heat exchanger (3), The second stage booster pump (4), the first stage fresh water tank (5), the n-1st plate heat exchanger (6), the n-1st stage booster pump (7), and the second stage fresh water tank ( 8), nth plate heat exchanger (9), nth booster pump (10), n-1 first fresh water tank (11), plate condenser (12), desulfurization wastewater pretreatment tank (13) Booster pump (14), n-stage fresh water tank (15), fresh water pump (16), fresh water tank (17), circulating water pump (18), concentrate treatment tank (19), n-stage transfer pump (20 ), three-way valve (21), n-stage flash tank (22), n-th grade transfer pump (23), n-th grade flash tank (24), second stage transfer pump (25) a second stage flash tank (26), a first stage transfer pump (27), a first stage flash tank (28), a boiler (29); The steam inlet of the first-stage plate heat exchanger (1) is connected to the steam outlet of the boiler (29) through a pipeline, and the condensed water outlet is connected to the inlet of the boiler (29) through a pipeline, and the inlet of the desulfurized waste water passes through the pipeline and the first stage rises The outlet of the pressure pump (2) is connected, and the outlet of the desulfurization waste water is connected to the first stage flash tank desulfurization wastewater inlet (39) through a pipeline; The second stage plate heat exchanger (3) steam inlet is connected to the first stage flash tank secondary steam outlet (36) through a pipe, and the condensed water outlet is connected to the first stage fresh water tank (5) through a pipe to desulfurize The waste water inlet is connected to the outlet of the second-stage booster pump (4) through a pipeline, and the outlet of the desulfurization waste water is connected to the inlet of the first-stage booster pump (2) through a pipeline; The steam inlet of the n-1st plate heat exchanger (6) is connected to the secondary steam outlet (36) of the n-2th flash tank through a pipeline, and the condensate outlet is passed through the pipeline and the n-2th fresh water tank. Connected, the desulfurization wastewater inlet is connected to the outlet of the n-1st stage booster pump (7) through a pipeline, and the desulfurization waste water outlet is connected to the inlet of the nth-stage booster pump through a pipeline; The steam inlet of the nth plate heat exchanger (9) is connected to the secondary steam outlet (36) of the n-1th flash tank through a pipeline, and the condensate outlet is passed through the pipeline and the n-1th fresh water tank (11) Connected, the desulfurization waste water inlet is connected to the outlet of the nth stage booster pump (10) through a pipeline, and the desulfurization waste water outlet is connected to the inlet of the n-1st stage booster pump (7) through a pipeline; The steam inlet of the plate condenser (12) is connected to the secondary steam outlet (36) of the nth stage flash tank through a pipeline, and the condensed water outlet is connected to the nth stage fresh water tank (15) through a pipeline, and the desulfurization waste water is imported through the pipeline. Connected to the outlet of the booster pump (14), the desulfurization waste water outlet is connected to the inlet of the nth stage booster pump (10) through a pipeline; The desulfurization wastewater pretreatment tank (13) is connected to the plate condenser (12) through a booster pump (14); the first stage fresh water tank (5) is connected to the second stage fresh water tank (8) through a pipeline. The second-stage fresh water tank (8) is connected to the third-stage fresh water tank through a pipeline, and the n-th grade fresh water tank (11) is connected to the n-th fresh water tank (15) through a pipeline, and the n-th fresh water tank (15) The fresh water pump (16) is connected to the fresh water tank (17); the first stage flash tank (28) discharge port passes through the first stage transfer pump (27) and the second stage flash tank (26) desulfurization waste water. The inlet is connected, and the second-stage flash tank (26) drain port is connected to the third-stage flash tank desulfurization wastewater inlet through the second-stage transfer pump (25), and the n-th-stage flash tank (24) drain port By n-1 The stage transfer pump (23) is connected to the n-stage flash tank (22) desulfurization waste water inlet, and the nth stage flash tank (22) discharge port passes through the nth stage transfer pump (20) and the concentrate treatment tank (19). Connected; the circulating pump (18) is connected to the three-way valve (21) through a pipe. The plate type multi-stage flash desulfurization wastewater treatment and recovery device according to claim 1, wherein the plate heat exchanger is formed by stacking a plurality of plates, and the plate comprises a positioning hole (30). Working fluid inlet and outlet (31), sealing ring (32), diversion zone (33), heat exchange zone (34), drop-shaped depression vortex (35); Positioning holes (30) are arranged in the middle of both sides of the plate, and the plate has four corners symmetrically provided with working medium inlet and outlet (31), a heat exchange zone (34) is arranged in the middle of the plate, and both sides of the heat exchange zone (34) There is a flow guiding zone (33), and a water droplet-shaped concave vortex (35) is arranged in the heat exchange zone (34), a flow guiding zone (33) on one side of the plate, a heat exchange zone (34) and two thermal working fluids. A sealing ring (32) is arranged around the outlet, and a drainage ring (32) is arranged on the other side of the plate, and a sealing ring (32) is arranged around the inlet and outlet of the two cold working fluids. The length of the vortex flow zone is 2R, the depth of the dent is 0.4R, the length of the vortex zone is R, and the vortex and vortex are arranged in a staggered manner. The vortex spacing in the flow direction is 5R, and the vortex spacing in the plate width direction is 4R. A plate type multi-stage flash desulfurization wastewater treatment and recovery apparatus according to claim 1, wherein said tail vortex zone has a length R of 4 - 10 mm. The plate type multi-stage flash desulfurization wastewater treatment and recovery device according to claim 1, wherein the flash tank comprises a secondary steam outlet (36), a pressure regulating valve (37), and a defoaming net. (38), desulfurization wastewater inlet (39), first baffle (40), second baffle (41), flange (42), screw (43), nut (44), descaling net (45 ), drain port (46), bracket (47); The flash tank is divided into upper and lower parts by flange (42), screw (43) and nut (44). The top of the flash tank is provided with a secondary steam outlet (36), and the upper part of the flash tank is adjusted. The pressure valve (37) has a desulfurization waste water inlet (39) in the middle of the flash tank, and a liquid discharge port (46) and a bracket (47) are arranged at the bottom of the flash tank, and the flash tank is provided from top to bottom. The foam net (38), the first baffle (40), the second baffle (41), the descaling net (45), and the descaling net (45) are fixed in the flash tank through a flange. A plate type multi-stage flash desulfurization wastewater treatment and recovery apparatus according to claim 4, wherein said defoaming net (38) and descaling net (45) are made of a wire mesh material. A plate type multi-stage flash desulfurization wastewater treatment and recovery method using the apparatus according to claim 1, characterized in that the booster pump (14) pumps the desulfurization waste water in the desulfurization wastewater pretreatment tank (13) into the plate condensation (12), the desulfurization waste water is heated by the secondary steam from the nth stage flash tank (22), and then sent to the nth stage plate heat exchanger (9) via the nth stage booster pump (10), the secondary steam After condensing, it enters the nth stage fresh water tank (15); the desulfurization waste water in the nth stage plate heat exchanger (9) is heated by the secondary steam from the nth level 1 flash tank (24) and passes through the n-1 The booster pump (7) is sent to the n-1st plate heat exchanger (6), and the secondary steam in the nth plate heat exchanger (9) is condensed and enters the n-1st fresh water tank (11). The desulfurization waste water in the n-1st plate heat exchanger (6) is heated by the secondary steam from the n-th grade flash tank and sent to the n-2 through the n-2 stage booster pump. The plate-type heat exchanger, the secondary steam in the n-1st plate heat exchanger (6) is condensed and enters the n-th class fresh water tank; the desulfurization wastewater in the second-stage plate heat exchanger (3) is from The secondary steam of the first stage flash tank (28) is heated and sent to the first stage plate heat exchanger (1) via the first stage booster pump (2), and the second stage plate heat exchanger (3) After the secondary steam is condensed, it enters the first-stage fresh water tank (5); the desulfurization waste water in the first-stage plate heat exchanger (1) is heated by the steam from the boiler (29) and enters the first-stage flash tank (28). After the steam is condensed, it is sent back to the boiler (29); the pressure of the first-stage flash tank (28) is adjusted by the pressure regulating valve (37) to flash the desulfurization wastewater, and the desulfurized wastewater flows through the first baffle (40). And the second baffle (41), the flashing time is extended, the secondary steam enters the second-stage plate heat exchanger (3), and the concentrated liquid is descaled by the descaling net (45) and then used by the first-stage pump ( 27) pumping into the second-stage flash tank (26); adjusting the pressure of the second-stage flash tank (26) through the pressure regulating valve (37) to flash the desulfurization wastewater, and the desulfurization wastewater sequentially flows through the first baffle Plate (40) and second baffle (41), causing flashing time delay Long, secondary steam enters the third-stage plate heat exchanger, and the concentrated liquid is descaled by the descaling net (45) and then pumped into the third-stage flash tank by the second-stage pump (25); through the pressure regulating valve (37) Adjusting the pressure of the n-th stage flash tank (24) to flash the desulfurization waste water, and the desulfurization waste water sequentially flows through the first baffle (40) and the second baffle (41) to make the flashing time Extending, the secondary steam enters the nth plate heat exchanger (9), and the concentrate is descaled by the descaling net (45) and pumped into the nth stage flash tank by the n-1th stage pump (23) (22) The pressure of the nth stage flash tank (22) is adjusted by the pressure regulating valve (37) to flash the desulfurization wastewater, and the desulfurization wastewater flows through the first baffle (40) and the second baffle (41). ), the flashing time is prolonged, the secondary steam enters the plate condenser (12), and the concentrated liquid is descaled by the descaling net (45), and then divided into two paths by the three-way valve (21), and one way is used as a circulating liquid by the circulating pump ( 18) pumping into the nth-stage plate heat exchanger (9) to maintain the continuous flashing process, and the other pump is pumped into the concentrate treatment tank (19) by the n-stage transfer pump (20) for centralized treatment; The fresh water in the water is sent back to the freshwater pool (17) via the fresh water pump (16). Use.

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