CN115745053A - Triple-effect flash evaporation desulfurization wastewater treatment method - Google Patents

Abstract

The application relates to a triple-effect flash evaporation desulfurization wastewater treatment method, which comprises the following steps: carrying out evaporation concentration on the wet desulphurization wastewater through a three-stage flash evaporation unit to obtain primary treatment liquid with crystal salt; carrying out secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid; carrying out precipitation treatment on the medium-grade treatment liquid; after precipitation, the solid waste is input into a plate-and-frame filter press for solid forming treatment, and supernatant liquid is led out to be used as final-stage treatment liquid. By arranging the three-stage flash evaporation unit, the wet desulphurization wastewater is heated and concentrated, so that the inorganic salt in the wastewater is precipitated. The high-temperature waste liquid after evaporation and heating and the precipitated inorganic salt enter a clarification tank for condensation, so that the waste liquid is cooled, and the inorganic salt is more fully precipitated. The precipitated inorganic salt and other impurities are subjected to precipitation treatment to realize solid-liquid separation, so that the wastewater treatment effect is achieved.

Description

Triple-effect flash evaporation desulfurization wastewater treatment method

Technical Field

The application relates to the technical field of coal-fired wet electro-desulfurization wastewater treatment, in particular to a three-effect flash evaporation desulfurization wastewater treatment method.

Background

A large amount of sulfur-containing flue gas generated by a coal-fired power plant is treated by wet desulphurization, and a limestone-gypsum wet desulphurization process is the most widely used method in flue gas desulphurization engineering of the coal-fired power plant. The desulfurization wastewater generated by the process has the characteristics of high salt content, high suspended matter content, high hardness, strong corrosivity and the like, and can be discharged only by being treated.

How to treat the wet desulphurization wastewater economically and environmentally becomes a problem to be solved urgently by the technical personnel in the field.

Disclosure of Invention

In view of this, the application provides a triple-effect flash evaporation desulfurization wastewater treatment method, which is used for realizing solid-liquid separation by carrying out flash evaporation heating concentration, condensation and precipitation on wastewater.

According to one aspect of the application, a three-effect flash evaporation desulfurization wastewater treatment method is provided, and comprises the following steps:

carrying out evaporation concentration on the wet desulphurization wastewater through a three-stage flash evaporation unit to obtain primary treatment liquid with crystal salt;

carrying out secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid;

carrying out precipitation treatment on the intermediate-grade treatment liquid;

after precipitation, the solid waste is input into a plate-and-frame filter press for solid forming treatment, and supernatant liquid is led out to be used as final-stage treatment liquid.

In one possible implementation, the tertiary flash unit includes a first flash unit, the second flash unit, and the third flash unit; the first flash unit, the second flash unit and the third flash unit are sequentially communicated;

the wet desulphurization wastewater is evaporated and concentrated by a three-stage flash evaporation unit, and the wet desulphurization wastewater is evaporated and concentrated by adopting the following method:

wet desulphurization wastewater enters the first flash unit through the feed inlet of the first flash unit for flash evaporation concentration treatment, the treated waste liquid is discharged from the discharge outlet of the first flash unit, and enters the second flash unit from the feed inlet of the second flash unit for flash evaporation concentration treatment; and discharging the treated waste liquid from a discharge hole of the second flash unit, and entering the third flash unit from a feed hole of the third flash unit for flash evaporation concentration treatment to obtain the primary treatment liquid.

In a possible implementation manner, the first flash unit, the second flash unit and the third flash unit are provided with condensed water outlets;

the first flash evaporation unit comprises a primary effect heater and a primary effect separator, a condensed water outlet of the primary effect flash evaporation unit is arranged at the bottom of the primary effect separator and is communicated with the primary effect heater through a primary effect circulating pump, and flash evaporation gas liquefied in the primary effect separator is sent into the primary effect heater to be heated and then is circulated into the primary effect separator;

the second flash evaporation unit comprises a secondary-effect heater and a secondary-effect separator, a condensed water outlet of the secondary-effect flash evaporation unit is arranged at the bottom of the secondary-effect separator and is communicated with the secondary-effect heater through a secondary-effect circulating pump, the flash evaporation gas liquefied in the secondary-effect separator is sent into the secondary-effect heater to be heated and then is circulated into the secondary-effect separator, and the secondary-effect heater is communicated with the primary-effect separator to receive the flash evaporation gas output by the primary-effect separator;

the third flash evaporation unit comprises a triple-effect heater and a triple-effect separator, a condensed water outlet of the triple-effect flash evaporation unit is arranged at the bottom of the triple-effect separator and is communicated with the triple-effect heater through a triple-effect circulating pump, the liquefied flash evaporation gas in the triple-effect separator is sent into the triple-effect heater to be heated and then is circulated into the triple-effect separator, and the triple-effect heater is communicated with the double-effect separator to receive the flash evaporation gas output by the double-effect separator.

In one possible implementation, the primary treatment liquid is subjected to a secondary condensation treatment, and the secondary condensation treatment is performed for cooling the primary treatment liquid by a heat exchanger.

In one possible implementation, the heat exchanger is a fluoroplastic heat exchanger.

In a possible implementation manner, the step of carrying out secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid, and the step of carrying out precipitation treatment on the intermediate treatment liquid are all completed in a clarification tank;

the heat exchanger is arranged at the middle upper part of the clarification tank, and the upper end of the heat exchanger does not exceed the upper end of the clarification tank;

subjecting the intermediate treatment liquid to a sedimentation treatment in a clarifier comprising:

the crystallized salt obtained by evaporation and concentration in the three-stage flash evaporation unit and the crystallized salt obtained by cooling and separating out in the clarification tank are precipitated to the bottom of the clarification tank under the action of gravity;

and inputting the crystallized salt and other impurities precipitated to the bottom of the clarification tank into the plate-and-frame filter press for solid forming treatment.

In a possible realization mode, the upper part of the clarification tank is provided with an overflow port for discharging the final treatment liquid;

and a sludge discharge port is arranged at the lower part of the clarification tank and communicated with the plate-and-frame filter press.

In one possible implementation manner, the fluoroplastic heat exchanger comprises a box body, a positioning plate and a fluoroplastic pipe;

the box body is of a square structure, an installation cavity is arranged inside the box body, a cooling liquid inlet and a cooling liquid outlet are arranged at the top of the box body, and the side surfaces of the box body, except the top and the bottom, on the periphery are provided with a plurality of through holes;

the number of the fluoroplastic pipes is multiple, the fluoroplastic pipes are arranged in an array form to form a pipe bundle, a preset distance is reserved between any two adjacent fluoroplastic pipes, the pipe bundle is in a U-shaped structure, one end of the pipe bundle is communicated with the cooling liquid inlet, and the other end of the pipe bundle is communicated with the cooling liquid outlet;

the number of the positioning plates is multiple, each positioning plate is provided with a plurality of positioning holes for the fluoroplastic pipes to pass through, the number of the positioning holes is the same as that of the fluoroplastic pipes, and the arrangement mode of the positioning holes on the positioning plates is the same as that of the fluoroplastic pipes;

the fluoroplastic pipes and the positioning plates are arranged in the installation cavity of the box body.

In one possible implementation manner, the fluoroplastic heat exchanger comprises a fluoroplastic pipe, a mounting rack and a fixing rack;

the pipe bundle comprises a plurality of fluoroplastic pipes, wherein the fluoroplastic pipes are arranged in parallel to form a pipe bundle, a preset distance is reserved between any two adjacent fluoroplastic pipes, the main body of the pipe bundle is circular, and the axes of the fluoroplastic pipes on the main body part of the pipe bundle are on the same plane;

the mounting frame is arranged above the clarification tank and is fixedly connected with the edge of the upper end of the clarification tank, one ends of the fluoroplastic pipes are arranged at one ends of the mounting frame and are used as cooling liquid inlets, and the other ends of the fluoroplastic pipes are arranged at the other ends of the mounting frame and are used as cooling liquid outlets;

the number of the positioning holes is the same as that of the fluoroplastic tubes, and the arrangement mode of the positioning holes on the fixing frame is the same as that of the fluoroplastic tubes.

In a possible implementation manner, the cooling liquid inlet of the fluoroplastic heat exchanger is communicated with the tail end steam outlet of the three-stage flash evaporation unit through a condenser.

The beneficial effect of this application: by arranging the three-stage flash evaporation unit, the wet desulphurization wastewater is heated and concentrated, so that the inorganic salt in the wastewater is precipitated. The high-temperature waste liquid after evaporation and heating and the precipitated inorganic salt enter a clarification tank for condensation, so that the waste liquid is cooled, and the inorganic salt is more fully precipitated. The precipitated inorganic salt and other impurities are subjected to precipitation treatment to realize solid-liquid separation, so that the wastewater treatment effect is achieved.

Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the application and, together with the description, serve to explain the principles of the application.

FIG. 1 is a flow chart of a three-way flash desulfurization wastewater treatment method according to an embodiment of the present application;

FIG. 2 shows a schematic diagram of a three-way flash desulfurization wastewater treatment system in accordance with one embodiment of the present application;

fig. 3 shows a block diagram of a fluoroplastic heat exchanger according to one embodiment of the present application;

fig. 4 shows a block diagram of a fluoroplastic heat exchanger according to another embodiment of the present application.

Detailed Description

Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

It is to be understood, however, that the terms "central," "longitudinal," "lateral," "length," "width," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing or simplifying the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present application. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present application.

FIG. 1 shows a flow chart of a three-effect flash evaporation desulfurization wastewater treatment method according to an embodiment of the present application. FIG. 2 shows a schematic diagram of a three-way flash desulfurization wastewater treatment system of one embodiment of the present application. Fig. 3 shows a block diagram of a fluoroplastic heat exchanger according to one embodiment of the present disclosure. Fig. 4 shows a block diagram of a fluoroplastic heat exchanger according to another embodiment of the present application. As shown in figure 1, the triple-effect flash evaporation desulfurization wastewater treatment method comprises the following steps: and (4) evaporating and concentrating the wet desulphurization wastewater through a three-stage flash evaporation unit to obtain primary treatment liquid with crystallized salt. And carrying out secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid. And (4) carrying out precipitation treatment on the medium-grade treatment liquid. After the precipitation, the solid waste is input to a plate and frame filter press 530 for solid forming treatment, and the supernatant is discharged as a final-stage treatment liquid.

And S001, heating and concentrating the wet desulphurization wastewater by arranging a three-stage flash evaporation unit to precipitate the inorganic salt in the wastewater. The high-temperature waste liquid after evaporation heating is subjected to condensation treatment in the step S100, so that the waste liquid is cooled, and inorganic salt is more sufficiently separated out. The inorganic salt and other impurities precipitated in step S200 are precipitated in the intermediate-stage treatment liquid, and solid-liquid separation is achieved. Step S300 is to output and treat the separated lower layer solid waste and the upper layer final treatment liquid respectively to achieve the treatment effect.

In one possible implementation, as shown in fig. 2, the three-stage flash unit includes a first flash unit 100, a second flash unit 200, and a third flash unit 300. The first flash unit 100, the second flash unit 200 and the third flash unit 300 are sequentially communicated. The wet desulphurization wastewater is evaporated and concentrated by a three-stage flash evaporation unit, and the wet desulphurization wastewater is evaporated and concentrated by adopting the following method: wet flue gas desulfurization waste water enters into first flash unit 100 through the feed inlet of first flash unit 100 and carries out the flash distillation concentration processing, and the waste liquid after the processing is got rid of from first flash unit 100 discharge gate, enters into second flash unit 200 from the feed inlet of second flash unit 200 and carries out the flash distillation concentration processing. The treated waste liquid is discharged from a discharge hole of the second flash unit 200, enters the third flash unit 300 from a feed hole of the third flash unit 300, and is subjected to flash evaporation concentration treatment to obtain primary treatment liquid. The first flash unit 100, the second flash unit 200 and the third flash unit 300 operate in series, wastewater is heated by flash steam in the first-effect separator 120, the wastewater subjected to evaporation concentration enters the second-effect separator 220 to be heated and concentrated by the flash steam again, the wastewater subjected to secondary concentration enters the third-effect separator 320 to be heated and concentrated by the flash steam again, so that inorganic salts in the wastewater are separated out, and solid-liquid separation is primarily realized.

In one possible implementation, the first flash unit 100, the second flash unit 200 and the third flash unit 300 are each provided with a condensed water outlet. The first flash unit 100 comprises a first-effect heater 110 and a first-effect separator 120, wherein a condensed water outlet of the first-effect flash unit is arranged at the bottom of the first-effect separator 120 and is communicated with the first-effect heater 110 through a first-effect circulating pump 130, and liquefied flash evaporation gas in the first-effect separator 120 is sent into the first-effect heater 110 to be heated and then is recycled into the first-effect separator 120. The second flash evaporation unit 200 comprises a secondary-effect heater 210 and a secondary-effect separator 220, a condensed water outlet of the secondary-effect flash evaporation unit is arranged at the bottom of the secondary-effect separator 220 and is communicated with the secondary-effect heater 210 through a secondary-effect circulating pump 230, the liquefied flash evaporation gas in the secondary-effect separator 220 is sent into the secondary-effect heater 210 to be heated and then is circulated into the secondary-effect separator 220, and the secondary-effect heater 210 is communicated with the primary-effect separator 120 to receive the flash evaporation gas output by the primary-effect separator 120. The third flash evaporation unit 300 comprises a triple-effect heater 310 and a triple-effect separator 320, a condensed water outlet of the triple-effect flash evaporation unit is arranged at the bottom of the triple-effect separator 320 and is communicated with the triple-effect heater 310 through a triple-effect circulating pump 330, the liquefied flash evaporation gas in the triple-effect separator 320 is sent into the triple-effect heater 310 to be heated and then is circulated into the triple-effect separator 320, and the triple-effect heater 310 is communicated with the double-effect separator 220 to receive the flash evaporation gas output by the double-effect separator 220. The flash steam which is not liquefied in the separator enters a heater of the next flash unit, the flash steam which is liquefied into condensed water enters the heater of the flash unit through a circulating pump to be heated into flash steam, and the flash steam which is not liquefied in the last flash unit enter the separator of the flash unit again. The consumption of flash steam is reduced, and the utilization rate of the flash steam and water resources is improved.

In one possible implementation, the primary treatment liquid is subjected to a secondary condensation treatment, which is performed for cooling the primary treatment liquid by a heat exchanger. The heat exchanger exchanges heat with high-temperature primary treatment liquid obtained through evaporation concentration through an external cold source, so that the saturated primary treatment liquid can more fully separate out crystalline salt, and the phenomenon that crystalline salt is continuously separated out before and after solid waste with wastewater enters the plate-and-frame filter press 530 to block filter cloth, a filtrate water system, pipelines and instrument measuring points of the plate-and-frame filter press 530 is avoided.

In one possible implementation, the heat exchanger is a fluoroplastic heat exchanger 520. The fluoroplastic has stable chemical performance and excellent anticorrosive performance. The fluoroplastic pipe has smooth wall surface, moderate flexibility and slight vibration during use, so that scaling is not easy to occur. The fluoroplastic heat exchanger has small volume and compact structure, and the heat transfer area in unit volume of the equipment is more than four times of that of a shell-and-tube heat exchanger of a metal tube. The flexible fluoroplastic pipe can be safely worked under the impact and vibration of fluid, and the pipe bundle can be made into various special shapes as required.

In one possible implementation, the secondary condensation of the primary treatment liquid in step S100 to obtain the secondary crystallized intermediate treatment liquid, and the sedimentation of the intermediate treatment liquid in step S200 are performed in the clarifier 510. The heat exchanger is arranged at the middle upper part of the clarification tank 510, and the upper end of the heat exchanger does not exceed the upper end of the clarification tank 510, so that the heat exchanger is completely immersed by primary treatment liquid as much as possible, and the optimal heat exchange effect is achieved. The intermediate-stage treatment liquid is subjected to a sedimentation treatment in the clarifier 510, including: the crystallized salt obtained by concentration by evaporation in the three-stage flash unit and the crystallized salt obtained by precipitation by cooling in the clarifier 510 are settled to the bottom of the clarifier 510 under the action of gravity. The crystallized salt and other impurities precipitated to the bottom of the clarifier 510 are input to a plate and frame filter press 530 for solid forming treatment. And realizing solid-liquid separation.

In other embodiments, a secondary crystallization device may be separately disposed before the clarifier 510, and the waste liquid may be subjected to secondary crystallization before flowing into the clarifier 510 for sedimentation. Certainly, the fluoroplastic heat exchanger 520 for secondary condensation is directly arranged at the upper part or the middle part of the clarification tank 510 in the embodiment, so that the equipment for secondary condensation and crystallization of the waste liquid is simpler and has lower cost.

In one possible implementation, the upper portion of the clarifier 510 is provided with an overflow port for discharging the final treatment liquid. The lower part of the clarification tank 510 is provided with a sludge discharge port which is communicated with the plate-and-frame filter press 530 through a sludge discharge pump 540. By providing an overflow port and a sludge discharge port, step S300 is performed to discharge the separated solid and liquid respectively out of the settling pond 510, thereby completing the treatment of the wet desulfurization wastewater.

In one possible implementation, as shown in fig. 3, the fluoroplastic heat exchanger 520 includes: a box 521, a positioning plate 523 and a fluoroplastic pipe 522. The box 521 is a square structure, and an installation cavity is arranged inside the box 521 and used for arranging the fluoroplastic pipe 522 and the positioning plate 523. The top of the tank 521 is provided with a coolant inlet 524 and a coolant outlet 525. The side surfaces of the box 521, except the top and the bottom, are all provided with a plurality of through holes, and waste water in the clarifier 510510 is subjected to heat exchange by immersing the fluoroplastic pipes 522 through the plurality of through holes. Fluoroplastics pipe 522 is a plurality of, and a plurality of fluoroplastics pipe 522 are the array formation tube bank of arranging, are equipped with between two arbitrary adjacent fluoroplastics pipe 522 and predetermine the distance, and the tube bank is the U-shaped structure, increases the area of contact of fluoroplastics pipe 522 and waste water, improves heat exchange efficiency. One end of the tube bundle is communicated with the cooling liquid inlet 524, and the other end of the tube bundle is communicated with the cooling liquid outlet 525, so that the cooling liquid flows in from the cooling liquid inlet 524, and flows out from the cooling liquid outlet 525 after heat exchange is completed. The fluoroplastic has the characteristics of extremely stable chemical property and good corrosion resistance, so that the fluoroplastic heat exchanger 520 can realize heat exchange on corrosive wastewater. And the fluoroplastic pipe 522 has smooth wall surface and moderate flexibility, and can be set according to the shape of the pipe bundle. The positioning plates 523 are plural and are used for maintaining the relative position relationship between the fluoroplastic pipes 522 and ensuring that the contact area between the fluoroplastic pipes 522 is not reduced due to contact. The plurality of positioning plates 523 are provided, each positioning plate 523 is provided with a plurality of positioning holes for the plurality of fluoroplastic tubes 522 to pass through, the number of the positioning holes is the same as that of the fluoroplastic tubes 522, and the arrangement mode of the plurality of positioning holes on the positioning plate 523 is the same as that of the plurality of fluoroplastic tubes 522. A plurality of fluoroplastic pipes 522 and a plurality of positioning plates 523 are arranged in the installation cavity of the box 521.

In another possible implementation, as shown in fig. 4, the fluoroplastic heat exchanger 520 includes fluoroplastic pipes 522, a mounting block 526, and a fixing block 527. The plurality of fluoroplastic tubes 522 are arranged in parallel to form a tube bundle, a preset distance is arranged between any two adjacent fluoroplastic tubes 522, the tube bundle main body is circular, and the axes of the plurality of fluoroplastic tubes 522 of the main body part of the tube bundle are on the same plane. A mounting frame 526 is disposed above the clarifier 510 and is fixedly connected to an upper edge of the clarifier 510, one end of the plurality of fluoroplastic pipes 522 is disposed at one end of the mounting frame 526 as a coolant inlet 524, and the other end of the plurality of fluoroplastic pipes 522 is disposed at the other end of the mounting frame 526 as a coolant outlet 525. The fixing frames 527 are multiple, and are used for maintaining the relative position relationship among the fluoroplastic tubes 522 and ensuring that the contact area between the fluoroplastic tubes 522 is not reduced due to contact, each fixing frame 527 is provided with multiple positioning holes for the multiple fluoroplastic tubes 522 to pass through, the number of the positioning holes is the same as that of the fluoroplastic tubes 522, and the arrangement mode of the multiple positioning holes on the fixing frame 527 is the same as that of the multiple fluoroplastic tubes 522.

Here, it should be noted that the number of the fluoroplastic heat exchangers 520 may be two or more. Two or more fluoroplastic heat exchangers 520 are arranged in parallel or in a matrix. The heat exchange efficiency is improved, and the crystal salt is more fully separated out.

In one possible implementation, the coolant inlet of fluoroplastic heat exchanger 520 is in communication with the terminal vapor outlet of the three-stage flash unit via condenser 400. The flash gas which is not liquefied in the third flash evaporation unit 300 is liquefied by cooling through the condenser 400, and is used as a cold source of the fluoroplastic heat exchanger 520, and a cooling liquid supply system does not need to be separately arranged.

Here, it should be noted that the coolant of the fluoroplastic heat exchanger 520 may also be water source generated by a plant unit such as main unit closed water, air cooler water, process water or industrial water, and the water source is reasonably utilized.

Here, it should be noted that, after heat exchange is completed, the condensed water flows out from the cooling liquid outlet 525, and the cooling liquid outlet 525 is communicated with the desulfurization process water tank 600 to collect the condensed water, thereby avoiding waste. The cooling liquid outlet 525 can also be communicated with a return water system of a power plant to reasonably utilize the condensed water.

Having described embodiments of the present application, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or improvements to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (10)

1. A three-effect flash evaporation desulfurization wastewater treatment method is characterized by comprising the following steps:

evaporating and concentrating the wet desulphurization wastewater through a three-stage flash evaporation unit to obtain primary treatment liquid with crystalline salt;

carrying out secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid;

carrying out precipitation treatment on the intermediate treatment liquid;

after precipitation, the solid waste is input into a plate-and-frame filter press for solid forming treatment, and supernatant liquid is led out to be used as final-stage treatment liquid.

2. The triple-effect flash desulfurization wastewater treatment process of claim 1, wherein said tertiary flash unit comprises a first flash unit, said second flash unit and said third flash unit; the first flash unit, the second flash unit and the third flash unit are sequentially communicated;

the wet desulphurization wastewater is evaporated and concentrated by a three-stage flash evaporation unit, and the wet desulphurization wastewater is evaporated and concentrated by adopting the following method:

wet desulphurization wastewater enters the first flash unit through the feed inlet of the first flash unit for flash evaporation concentration treatment, the treated waste liquid is discharged from the discharge outlet of the first flash unit, and enters the second flash unit from the feed inlet of the second flash unit for flash evaporation concentration treatment; and discharging the treated waste liquid from a discharge hole of the second flash evaporation unit, and entering the third flash evaporation unit from a feed hole of the third flash evaporation unit for flash evaporation concentration treatment to obtain the primary treatment liquid.

3. The triple-effect flash desulfurization wastewater treatment method according to claim 2, wherein the first flash unit, the second flash unit and the third flash unit are provided with condensed water outlets;

the first flash evaporation unit comprises a primary effect heater and a primary effect separator, a condensed water outlet of the primary effect flash evaporation unit is arranged at the bottom of the primary effect separator and is communicated with the primary effect heater through a primary effect circulating pump, and flash evaporation gas liquefied in the primary effect separator is sent into the primary effect heater to be heated and then is circulated into the primary effect separator;

the second flash evaporation unit comprises a secondary-effect heater and a secondary-effect separator, a condensed water outlet of the secondary-effect flash evaporation unit is arranged at the bottom of the secondary-effect separator and is communicated with the secondary-effect heater through a secondary-effect circulating pump, the flash evaporation gas liquefied in the secondary-effect separator is sent into the secondary-effect heater to be heated and then is circulated into the secondary-effect separator, and the secondary-effect heater is communicated with the primary-effect separator to receive the flash evaporation gas output by the primary-effect separator;

the third flash evaporation unit comprises a triple effect heater and a triple effect separator, a condensed water outlet of the triple effect flash evaporation unit is arranged at the bottom of the triple effect separator and is communicated with the triple effect heater through a triple effect circulating pump, the liquefied flash evaporation gas in the triple effect separator is sent into the triple effect heater to be heated and then is circulated into the triple effect separator, and the triple effect heater is communicated with the double effect separator to receive the flash evaporation gas output by the double effect separator.

4. The process of claim 1, wherein the primary treatment liquid is subjected to secondary condensation, and the secondary condensation is performed to cool the primary treatment liquid by a heat exchanger.

5. The triple-effect flash desulfurization wastewater treatment method according to claim 4, wherein the heat exchanger is a fluoroplastic heat exchanger.

6. The triple-effect flash evaporation desulfurization wastewater treatment method according to claim 4 or 5, wherein the step of performing secondary condensation treatment on the primary treatment liquid to obtain secondary crystallized intermediate treatment liquid, and the step of performing precipitation treatment on the intermediate treatment liquid are both performed in a clarifier;

the heat exchanger is arranged at the middle upper part of the clarification tank, and the upper end of the heat exchanger does not exceed the upper end of the clarification tank;

subjecting the intermediate treatment liquid to a sedimentation treatment in the clarifier tank, comprising:

the crystallized salt obtained by evaporation and concentration in the three-stage flash evaporation unit and the crystallized salt obtained by cooling and separating out in the clarification tank are precipitated to the bottom of the clarification tank under the action of gravity;

and inputting the crystallized salt and other impurities precipitated to the bottom of the clarification tank into the plate-and-frame filter press for solid forming treatment.

7. The triple-effect flash evaporation desulfurization wastewater treatment method according to claim 6, characterized in that an overflow port is provided at the upper part of the clarifier for discharging the final treatment liquid;

and a sludge discharge port is arranged at the lower part of the clarification tank and communicated with the plate-and-frame filter press.

8. The triple-effect flash evaporation desulfurization wastewater treatment method according to claim 6, wherein the fluoroplastic heat exchanger comprises a tank body, a positioning plate and a fluoroplastic pipe;

the box body is of a square structure, an installation cavity is arranged inside the box body, a cooling liquid inlet and a cooling liquid outlet are arranged at the top of the box body, and the side surfaces of the box body, except the top and the bottom, on the periphery are provided with a plurality of through holes;

the number of the fluoroplastic pipes is multiple, the fluoroplastic pipes are arranged in an array form to form a pipe bundle, a preset distance is reserved between any two adjacent fluoroplastic pipes, the pipe bundle is in a U-shaped structure, one end of the pipe bundle is communicated with the cooling liquid inlet, and the other end of the pipe bundle is communicated with the cooling liquid outlet;

the number of the positioning plates is multiple, each positioning plate is provided with a plurality of positioning holes for the fluoroplastic pipes to pass through, the number of the positioning holes is the same as that of the fluoroplastic pipes, and the arrangement mode of the positioning holes on the positioning plates is the same as that of the fluoroplastic pipes;

the fluoroplastic pipes and the positioning plates are arranged in the installation cavity of the box body.

9. The triple-effect flash evaporation desulfurization wastewater treatment method according to claim 6, wherein the fluoroplastic heat exchanger comprises a fluoroplastic pipe, a mounting frame and a fixing frame;

the pipe bundle comprises a plurality of fluoroplastic pipes, wherein the fluoroplastic pipes are arranged in parallel to form a pipe bundle, a preset distance is reserved between any two adjacent fluoroplastic pipes, the main body of the pipe bundle is circular, and the axes of the fluoroplastic pipes on the main body part of the pipe bundle are on the same plane;

the mounting frame is arranged above the clarification tank and is fixedly connected with the edge of the upper end of the clarification tank, one ends of the fluoroplastic pipes are arranged at one ends of the mounting frame and are used as cooling liquid inlets, and the other ends of the fluoroplastic pipes are arranged at the other ends of the mounting frame and are used as cooling liquid outlets;

the number of the positioning holes is the same as that of the fluoroplastic tubes, and the arrangement mode of the positioning holes on the fixing frame is the same as that of the fluoroplastic tubes.

10. The triple-effect flash desulfurization wastewater treatment method of claim 8 or 9, wherein the cooling liquid inlet of the fluoroplastic heat exchanger is communicated with the terminal steam outlet of the third-stage flash unit through a condenser.

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