Limestone desulfurization wastewater treatment method

Abstract

The invention discloses a limestone desulfurization wastewater treatment method, which is based on a conventional desulfurization wastewater high-temperature evaporation treatment process, high-temperature flue gas is divided into two flue gas streams, and one flue gas stream is subjected to dust removal and compression and then is merged into a desulfurization wastewater inlet pipe, so that the initial temperature of the desulfurization wastewater entering an evaporation tower is increased, and the desulfurization wastewater can be recycled. And for the other stream of smoke flow, under the synergistic effect of a smoke diffusion mechanism and a flow guide structure in the evaporation tower, the other stream of smoke flow is conveyed downwards to different positions and then reversely flows upwards to be in contact with the fog drops, so that not only is the conveying and diffusion direction of the smoke flow controlled, but also the heat medium is effectively transferred; according to the device, efficient dispersion contact of flue gas and fog drops is achieved, the evaporation effect is improved, downward fog drops which do not fully react are evaporated, in addition, multiple sets of rotating heat transfer scrapers are matched, on one hand, the flue gas and the fog drops which are in up-down countercurrent contact are rotationally stirred, and on the other hand, crystals are scraped.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more specifically, to a treatment method for limestone desulfurization wastewater. Background Art

[0002] In the process of flue gas desulfurization by the limestone-gypsum method, in order to maintain the material balance of the slurry circulation system of the desulfurization device, prevent the concentration of soluble parts in the flue gas, i.e., chloride ions, from exceeding the specified value, and ensure the quality of gypsum, a certain amount of wastewater needs to be discharged from the system. These wastewaters mainly come from the gypsum dehydration and cleaning systems. The composition of the limestone-gypsum flue gas desulfurization wastewater is relatively complex, mainly including suspended solids, supersaturated sulfites, sulfates, and heavy metals, etc.

[0003] The traditional zero discharge of desulfurization wastewater mainly has two methods. One method is to directly introduce the desulfurization wastewater into the original flue for evaporation, and the other method is to separately set up a wastewater evaporation system to introduce the desulfurization wastewater into a separately set evaporation tower device for water evaporation. For example, the patent number CN109650476A discloses a desulfurization wastewater zero discharge system and method, in which compressed air and desulfurization wastewater enter a two-fluid spray gun for atomization and are evaporated by hot flue gas in an evaporation furnace. After the evaporated mixed flue gas is dust-removed by a cyclone dust collector, it flows out of the bypass system.

[0004] That is, in the prior art, only the wastewater is sprayed into a high-temperature evaporation device, and the flue gas moves from bottom to top, making it difficult to control the flue gas distribution. Therefore, in a large treatment space, it is impossible to achieve uniform and sufficient contact between the wastewater and the flue gas, which affects the evaporation effect of the wastewater. Even some wastewater fails to be completely evaporated and enters the electrostatic precipitator with the soot or falls with the crystals. Especially for the high-temperature flue gas of the flue without a dust removal process, the flue gas contains a large amount of dust particles. The water vapor in the evaporation process promotes an increase in the specific gravity and viscosity of the ash in the flue gas, and serious ash accumulation and crystallization will occur on the wall surface and supports of the evaporation device, ultimately resulting in serious scaling and corrosion of the inner wall of the dust collector and the evaporation device. Summary of the Invention

[0005] The purpose of the present invention is to solve the existing problems and provide a treatment method for limestone desulfurization wastewater compared with the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A treatment method for limestone desulfurization wastewater, comprising the following steps: S1. Wastewater atomization spraying: Using a desulfurization wastewater inlet pipe to introduce the desulfurization wastewater into an atomizer at the top of an evaporation tower to form an atomization spraying environment from top to bottom; S2. Flue gas diversion treatment: Use a flue gas diversion treatment device to divide the high-temperature flue gas into two streams. One stream is directly introduced into the evaporation tower from the top, and the other stream is dust-removed and pressurized and then introduced into the desulfurized wastewater inlet pipe to be mixed with the desulfurized wastewater. After being atomized by the atomizer, it is sprayed downward. S3. Evaporation and concentration treatment: The flue gas stream introduced from the top of the evaporation tower enters the flue gas diffusion mechanism. Most of the flue gas overflows from the bottom air outlet of the evaporation ball and then evenly diffuses upward along the inner guide surface of the guide structure, making a countercurrent contact with the downwardly sprayed droplets. A small part of the flue gas overflows from the bottom end of the guide pipe and moves upward to evaporate the downward flowing desulfurized wastewater droplets that have not fully reacted. During this process, start multiple groups of heat transfer scraping blades annularly distributed inside the guide structure to perform a rotating scraping action on the evaporation ball and the inner end wall of the guide structure. On the one hand, rotate and stir the countercurrently contacting flue gas and droplets, and on the other hand, scrape off the crystals formed and attached. S4. Flue gas discharge treatment: The steam, along with the cooled flue gas, is discharged into the second dust collector of the electrostatic precipitator through the steam discharge pipe, and then is discharged from the chimney after being treated by the condensation device. S5. Waste discharge treatment: The generated crystals are scraped downward by the heat transfer scraping blades and continuously discharged along the guide structure and the discharge inclined pipe.

[0007] Further, the flue gas diversion treatment device includes a flue gas inlet pipe connected to the original flue. The other end of the flue gas inlet pipe is connected with a first flue gas branch pipe and a second flue gas branch pipe. The other end of the first flue gas branch pipe directly leads to the inner top of the evaporation tower, and the other end of the second flue gas branch pipe leads to the first electrostatic precipitator. The exhaust port of the first electrostatic precipitator is connected with an air compressor, and the air outlet of the air compressor is connected with a diversion pipe communicated with the desulfurized wastewater inlet pipe.

[0008] Further, the atomizer includes a fixing plate fixedly installed on the inner top of the evaporation tower. The fixing plate is provided with an annular pipe connected to the lower end of the desulfurized wastewater inlet pipe, and a plurality of atomizing nozzles penetrating below the fixing plate are annularly distributed at the lower end of the annular pipe.

[0009] Further, the guide structure includes a guide seat fixedly installed inside the evaporation tower and located below the evaporation ball. The bottom end of the guide seat is fixedly provided with a discharge straight pipe extending downward.

[0010] Further, the upper end of the evaporation ball is provided with an adapter pipe fixedly installed on the fixing plate and communicated with the first flue gas branch pipe. The evaporation ball internally is provided with an inner heating cavity and an outer heat conduction cavity distributed inside and outside. The upper and lower ends of the outer heat conduction cavity are respectively communicated with the adapter pipe and the bottom air outlet of the evaporation ball.

[0011] Further, the upper end of the guide pipe is fixedly installed at the air outlet of the evaporation ball, and its lower end extends to the bottom of the discharge straight pipe. The top end of the guide pipe is provided with an upper air inlet communicated with the air outlet, and the bottom end of the guide pipe is provided with a plurality of downwardly inclined lower air outlets.

[0012] Furthermore, the heat transfer scraping blade includes a lower blade body rotatably installed inside the straight discharge pipe and movably arranged on the outer wall of the diversion pipe. An upper blade body adapted to the inner wall of the diversion seat and the outer wall of the evaporation sphere is fixed to the upper end of the lower blade body.

[0013] Furthermore, a rotating gear ring fixedly connected to the outer walls of a plurality of lower blade bodies is rotatably embedded and installed inside the top end of the straight discharge pipe. A rotating gear meshing with the rotating gear ring is rotatably driven and installed at the bottom end of the evaporation tower.

[0014] Compared with the prior art, the advantages of the present invention are as follows: Based on the conventional high-temperature evaporation treatment process for desulfurized wastewater, this solution divides the high-temperature flue gas into two flue gas streams. For one flue gas stream, after dust removal and compression, it is incorporated into the desulfurized wastewater inlet pipe, which not only increases the initial temperature of the desulfurized wastewater entering the evaporation tower but also improves the downward diffusion degree of the droplets under the action of the flue gas assisting flow. For the other flue gas stream, a flue gas diffusion mechanism composed of an evaporation sphere and a diversion pipe is added inside the evaporation tower, which transports to different positions downward and then flows upward in a reverse direction to contact the desulfurized wastewater spray. This not only controls the conveying and diffusion direction of the flue gas stream but also serves as a heat conduction surface for heat medium transfer. It not only effectively realizes the efficient dispersion of the flue gas around the evaporation sphere and uniform contact with the downwardly sprayed droplets, improving the heat exchange and evaporation effect, but also enables the small amount of downward flue gas to flow upward in a reverse direction to evaporate the downward desulfurized wastewater droplets that have not fully reacted. In addition, a plurality of groups of heat transfer scraping blades that can be rotationally driven are arranged inside the diversion structure. The heat transfer scraping blades perform rotational scraping actions on the evaporation sphere and the inner end wall of the diversion structure. On the one hand, the upward and downward countercurrent contacting flue gas and droplets are rotationally stirred, and the heat transfer between the evaporation sphere and a plurality of groups of upper blade bodies is utilized to promote the heat exchange between the flue gas and the droplets, accelerating evaporation and crystallization. On the other hand, the crystals attached to the inner walls of the evaporation sphere and the diversion structure are scraped off, making it not easy to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flowchart of the method of the present invention; Figure 2 is a schematic structural diagram of the device involved in the present invention; Figure 3 is a partial cross-sectional view inside the evaporation tower of the present invention; Figure 4 is a bottom view of the flue gas diffusion mechanism of the present invention; Figure 5 is an overall cross-sectional view inside the evaporation tower of the present invention; Figure 6 is a schematic structural diagram of the heat transfer scraping blade of the present invention; Figure 7 is a cross-sectional view inside the evaporation tower during the high-temperature evaporation treatment process of the present invention.

[0016] Description of reference numerals in the figure: 1. Evaporation tower; 101. Outer straight tube; 102. Discharge inclined tube; 2. Flue gas inlet pipe; 201. Flue gas branch pipe 1; 202. Flue gas branch pipe 2; 3. Electrostatic precipitator 1; 4. Air compressor; 401. Drainage pipe; 5. Desulfurized wastewater inlet pipe; 501. Atomizing nozzle; 6. Fixed plate; 7. Evaporation ball; 701. Connecting pipe; 702. Outer heat conduction cavity; 8. Flow guide seat; 9. Heat transfer scraping blade; 91. Upper blade body; 92. Lower blade body; 10. Discharge straight pipe; 11. Flow guide pipe; 111. Upper air inlet; 112. Lower exhaust port; 12. Steam discharge pipe; 13. Electrostatic precipitator 2; 14. Condensing device; 15. Chimney. Specific implementation mode

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0018] Embodiment 1: In view of the fact that in the prior art, during the high-temperature evaporation of desulfurized wastewater using high-temperature flue gas, it is difficult to control the flue gas distribution. Therefore, in a relatively large treatment space, it is impossible to achieve uniform and sufficient contact between the wastewater and the flue gas, which affects the evaporation effect of the wastewater. Even in some cases, part of the wastewater fails to be completely evaporated and enters the dust collector together with the soot or falls with the crystals. The following technical solutions are proposed: The present invention discloses a method for treating limestone desulfurized wastewater. Please refer to Figures 1-7 , including the following steps: S1. Wastewater atomization spraying: First, add lime milk solution to the wastewater to neutralize and adjust the pH value, then add organic sulfur, coagulant and coagulant aid to the wastewater to promote the precipitation of impurities such as heavy metals and suspended solids. Finally, through clarification, concentration and pressure filtration dehydration, the separation of sludge and wastewater is achieved, and the pretreated desulfurized wastewater is obtained. The desulfurized wastewater is introduced into the atomizer at the top of the evaporation tower 1 through the desulfurized wastewater inlet pipe 5 to form an atomization spraying environment from top to bottom; S2. Flue gas shunt treatment: Use a flue gas shunt treatment device to divide the high-temperature flue gas into two smoke streams. One stream is directly introduced into the evaporation tower 1 from the top, and the other stream is introduced into the desulfurized wastewater inlet pipe 5 after dust removal and pressure increase, and is mixed with the desulfurized wastewater and atomized and sprayed downward together by the atomizer; S3. Evaporation and concentration treatment: The smoke flow introduced from the top of the evaporation tower 1 enters the flue gas diffusion mechanism. Most of the smoke flow overflows from the bottom air outlet of the evaporation ball 7 and then evenly diffuses upward along the inner guiding surface of the guiding structure located below the evaporation ball 7, making countercurrent contact with the downward sprayed droplets. A small part of the smoke flow enters the guiding pipe 11 from the bottom of the evaporation ball 7, overflows from the bottom end of the guiding pipe 11 and then moves upward to evaporate the downward flowing desulfurized wastewater droplets that have not fully reacted. During this process, a plurality of groups of heat transfer scraping blades 9 annularly distributed inside the guiding structure are started. The heat transfer scraping blades 9 make a rotational scraping action on the evaporation ball 7 and the inner end wall of the guiding structure. On the one hand, the countercurrent contacted flue gas and droplets are rotationally stirred, and on the other hand, the crystals attached to the evaporation ball 7 and the inner wall of the guiding structure are scraped downward. S4. Flue gas discharge treatment: The evaporated steam, along with the cooled flue gas, is discharged into the second electrostatic precipitator 13 through the steam discharge pipe 12. The steam pollutants and the dust in the original flue gas are removed together in the second electrostatic precipitator 13, and then are discharged from the chimney 15 after being treated by the condensation device 14. S5. Waste discharge treatment: The water vapor in the evaporation process causes the specific gravity and viscosity of the ash in the flue gas to increase, promoting the adhesion of dust particles to the crystals. Under the rotational action of the external heat transfer scraping blades 9, they are discharged along the guiding structure and the discharge inclined pipe 102 at the bottom of the evaporation tower 1.

[0019] Embodiment 2: In this embodiment, the flue gas diversion treatment device involved in the treatment method of Embodiment 1 is described in detail as follows: Please refer to Figure 2 , Figure 3 , in which the flue gas diversion treatment device includes a flue gas inlet pipe 2 connected to the original flue. The other ends of the flue gas inlet pipe 2 are jointly connected to a first flue gas branch pipe 201 and a second flue gas branch pipe 202. The other end of the first flue gas branch pipe 201 directly leads to the inner top of the evaporation tower 1. The other end of the second flue gas branch pipe 202 leads to the first electrostatic precipitator 3. The exhaust port of the first electrostatic precipitator 3 is connected to an air compressor 4. The air outlet of the air compressor 4 is connected to a diversion pipe 401 communicated with the desulfurized wastewater inlet pipe 5. The atomizer includes a fixing plate 6 fixedly installed at the inner top of the evaporation tower 1. The fixing plate 6 is provided with an annular pipe connected to the lower end of the desulfurized wastewater inlet pipe 5. A plurality of atomizing nozzles 501 penetrating below the fixing plate 6 are annularly distributed at the lower end of the annular pipe. The high-temperature flue gas is divided into two flue gas streams. One stream directly enters the top of the evaporation tower 1 through the first flue gas branch pipe 201 and is connected to the flue gas diffusion mechanism inside the evaporation tower 1. The other stream passes through dust removal and pressure boosting and then enters the desulfurized waste water inlet pipe 5, where it is mixed with the desulfurized waste water and atomized by multiple atomizing nozzles 501 on the atomizer and sprayed downward. On the one hand, it increases the initial temperature of the desulfurized waste water entering the evaporation tower 1 and preheats it for subsequent evaporation and concentration. On the other hand, after pressure boosting, the atomization degree is improved, and under the action of the flue gas assisting flow, the downward spraying and diffusion degree of the droplets is increased, so as to further realize the uniform and sufficient contact between the waste water and the flue gas.

[0020] Please refer to Figure 3 , the diversion structure includes a diversion seat 8 fixedly installed inside the evaporation tower 1 and located below the evaporation sphere 7. The diversion seat 8 is a hollow conical structure with a wider upper part and a narrower lower part. The bottom end of the diversion seat 8 is fixedly provided with a discharge straight pipe 10 extending downward. The bottom of the evaporation tower 1 is a bucket-shaped structure with a wider upper part and a narrower lower part. The bottom of the evaporation tower 1 is fixedly provided with an outer straight tube 101 located outside the discharge straight pipe 10 and used for fixedly installing the discharge straight pipe 10. The bottom end of the discharge straight pipe 10 is fixedly connected with a discharge inclined pipe 102 that penetrates outside the outer straight tube 101 and is inclined downward.

[0021] Please refer to Figures 3-7 , the flue gas diffusion mechanism is composed of an evaporation sphere 7 and a diversion pipe 11 below it. The upper end of the evaporation sphere 7 is provided with a connecting pipe 701 fixedly installed on the fixing plate 6 and connected to the first flue gas branch pipe 201. The evaporation sphere 7 is internally provided with an inner heating cavity and an outer heat conduction cavity 702 distributed inside and outside. The upper and lower ends of the outer heat conduction cavity 702 are respectively connected to the connecting pipe 701 and the air outlet at the bottom end of the evaporation sphere 7. A heater is installed in the heating cavity, and the heater is used to control the evaporation environment temperature inside the evaporation sphere 7 and the evaporation tower 1. The upper end of the diversion pipe 11 is fixedly installed at the air outlet of the evaporation sphere 7, and its lower end extends to the bottom of the discharge straight pipe 10. The top end of the diversion pipe 11 is provided with an upper air inlet 111 connected to the air outlet, and the bottom end of the diversion pipe 11 is provided with a plurality of downwardly inclined lower exhaust ports 112. The evaporation sphere 7 and the inner walls of the evaporation tower 1 and the diversion seat 8 form the main evaporation space, and the plurality of atomizing nozzles 501 are arranged downward and annularly distributed above the main evaporation space; The high-temperature flue gas directly introduced into the top of the evaporation tower 1 from the flue gas inlet pipe 2 and the first flue gas branch pipe 201 is introduced into the outer heat conduction cavity 702 through the connecting pipe 701. The outer heat conduction cavity 702 is a hollow circular ring surface, which is used for the high-temperature flue gas to diffuse efficiently inside the evaporation sphere 7 and transfer heat to the outer surface of the evaporation sphere 7. Most of the high-temperature flue gas is discharged from the air outlet at the bottom end of the evaporation sphere 7 and then diffuses upward to the main evaporation space under the diversion of the diversion seat 8 and the outer circular end face of the evaporation sphere 7, effectively controlling the conveying and diffusion direction of the flue gas flow, so that it diffuses upward and impacts and contacts the downwardly sprayed water mist in the effective space, improving the heat exchange and evaporation effect; A small amount of flue gas enters the draft tube 11 through the upper air inlet 111 on the draft tube 11, moves downward in the draft tube 11 for a certain distance, overflows through the lower exhaust port 112, and moves upward in the reverse direction along the inner wall of the discharge straight pipe 10. The evaporation ball 7, the draft tube 11, the draft guide seat 8, and the discharge straight pipe 10 are all made of heat-conducting materials. The inner diameter of the discharge straight pipe 10 is much smaller than the opening diameter of the upper end of the draft guide seat 8. A small amount of flue gas is introduced downward from the draft tube 11 into the discharge straight pipe 10 and then moves upward from the lower end of the discharge straight pipe 10. The discharge straight pipe 10 serves as a secondary evaporation space, reducing heat dissipation in a confined space, drying and evaporating a small amount of unreacted desulfurized wastewater droplets moving downward, and reducing the humidity of the crystals. Therefore, during the rotation of multiple heat transfer scraping blades 9, the crystals attached to the end wall of the support can be easily scraped off and peeled off.

[0022] Among them, the structure and driving method of the heat transfer scraping blade 9 are described in detail as follows: Please refer to Figures 5-7 , the heat transfer scraping blade 9 includes a lower blade body 92 rotatably installed inside the discharge straight pipe 10 and movably attached to the outer wall of the draft tube 11. The upper end of the lower blade body 92 is fixed with an upper blade body 91 adapted to the inner wall of the draft guide seat 8 and the outer wall of the evaporation ball 7. The inner side of the top end of the discharge straight pipe 10 is rotatably embedded with a rotating gear ring fixedly connected to the outer walls of multiple lower blade bodies 92. A rotating gear meshing with the rotating gear ring is installed at the bottom end of the evaporation tower 1 by means of rotational drive. A drive motor for rotating the drive gear is installed on the side wall at the bottom end of the evaporation tower 1.

[0023] Multiple heat transfer scraping blades 9 are annularly distributed between the flue gas diffusion mechanism and the draft structure. When the drive motor is started, multiple heat transfer scraping blades 9 rotate along the axis of the evaporation tower 1 and perform a rotating stirring action. On the one hand, it rotates and stirs the flue gas and droplets in countercurrent contact up and down, which not only promotes the impact contact between the two but also effectively extends the treatment time of the high-temperature flue gas, and uses the heat transfer between the evaporation ball 7 and multiple upper blade bodies 91 to promote the heat exchange between the flue gas and the droplets, accelerating evaporation and crystallization. On the other hand, the rotating stirring action is regarded as a rotating scraping action to scrape the crystals attached to the inner walls of the evaporation ball 7, the draft tube 11, the draft guide seat 8, and the discharge straight pipe 10, which is not easy to scale. The scraped crystals fall along the draft guide seat 8 and the discharge straight pipe 10 and are discharged by the discharge inclined pipe 102.

[0024] To sum up: Based on the conventional high-temperature evaporation treatment process of desulfurized wastewater, the high-temperature flue gas is divided into two streams. For one stream of flue gas, after dust removal and compression, it is incorporated into the desulfurized wastewater inlet pipe. On the one hand, it increases the initial temperature of the desulfurized wastewater entering the evaporation tower 1. On the other hand, after pressurization, the atomization degree is improved, and under the action of the flue gas assisting flow, the downward diffusion degree of the droplets is increased, so as to further achieve uniform and sufficient contact between the wastewater and the flue gas; For another smoke flow, a flue gas diffusion mechanism composed of evaporation balls 7 and diversion pipes 11 is additionally arranged inside the evaporation tower 1 to convey to different positions downward and then flow upward in a reverse manner to contact with the desulfurized waste water spray. Among them, the heat transfer scraping blades 9 are used for the main smoke flow conveyance. They not only control the conveyance and diffusion direction of the smoke flow, but also serve as a heat conduction surface for heat medium transfer. This effectively realizes the efficient dispersion of the flue gas around the evaporation balls 7 and the uniform contact with the downwardly sprayed droplets, improves the heat exchange and evaporation effect, and also enables a small amount of downward flowing flue gas to flow upward in a reverse manner to evaporate the downwardly flowing desulfurized waste water droplets that have not fully reacted. In addition, a plurality of rotatable and drivable heat transfer scraping blades 9 are arranged inside the diversion structure. The heat transfer scraping blades 9 perform rotational scraping actions on the evaporation balls 7 and the inner end wall of the diversion structure. On the one hand, they rotate and stir the upward and downward counter-flowing flue gas and droplets, and promote the heat exchange between the flue gas and the droplets by the heat transfer between the heat transfer scraping blades 9 and the plurality of upper blade bodies 91, accelerating evaporation and crystallization. On the other hand, they scrape off the crystals attached to the evaporation balls 7 and the inner wall of the diversion structure, making it not easy to scale.

[0025] The above is only a preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto; any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for treating limestone desulfurization wastewater, characterized in that: The following steps are involved: S1. Wastewater atomization spraying: Use the desulfurization wastewater inlet pipe to pass the desulfurization wastewater into the atomizer at the top of the evaporation tower to form an atomization spray environment from top to bottom; S2. Flue gas diversion treatment: The high-temperature flue gas is divided into two streams by using a flue gas diversion treatment device. One stream is directly introduced into the evaporation tower from the top, and the other stream is introduced into the desulfurization wastewater inlet pipe after dust removal and pressurization, mixed with the desulfurization wastewater, and then atomized by the atomizer and sprayed downward; S3, evaporation concentration treatment: the smoke flow introduced from the top of the evaporation tower enters the smoke diffusion mechanism, most of the smoke flow overflows from the bottom outlet of the evaporation ball and diffuses upward evenly along the guide surface in the guide structure, and contacts the droplets sprayed downward in countercurrent. A small part of the smoke flow overflows from the bottom of the guide pipe and moves upward to evaporate the desulfurization wastewater droplets that have not fully reacted downward; In this process, multiple groups of heat transfer scrapers distributed in an annular manner on the inner side of the guide structure are activated to perform a rotating scraping action on the evaporation ball and the inner end wall of the guide structure, which can not only rotate and stir the flue gas and droplets in countercurrent contact, but also scrape off the attached crystals. S4, flue gas external exhaust treatment: steam is discharged into the second electrostatic precipitator for dust removal through the steam exhaust pipe along with the cooled flue gas, and then discharged from the chimney after being treated by the condensing device; S5. Waste discharge treatment: The generated crystals are scraped downwards by the heat transfer scraper and continuously discharged along the guide structure and the discharge inclined pipe.

2. A method for treating limestone desulfurization wastewater according to claim 1, characterized in that: The flue gas diversion treatment device includes a flue gas inlet pipe connected to the original flue, the other end of the flue gas inlet pipe is connected to a flue gas branch pipe 1 and a flue gas branch pipe 2, and the other end of the flue gas branch pipe 1 directly leads to the top of the evaporation tower; The other end of the flue gas branch pipe 2 leads to the electrostatic precipitator 1, the exhaust port of the electrostatic precipitator 1 is connected to an air compressor, and the air compressor outlet is connected to a drainage pipe connected to the desulfurization wastewater inlet pipe.

3. A method for treating limestone desulfurization wastewater according to claim 2, characterized in that: The atomizer includes a fixed plate fixedly installed on the top of the evaporation tower, on which an annular tube connected to the lower end of the desulfurization wastewater inlet pipe is provided, and a plurality of atomizing nozzles penetrating to the bottom of the fixed plate are distributed in an annular manner at the lower end of the annular tube.

4. A method for treating limestone desulfurization wastewater according to claim 3, characterized in that: The flow guiding structure comprises a flow guiding seat which is fixedly installed inside the evaporation tower and located below the evaporation ball, and a discharge straight pipe extending downward is fixed at the bottom end of the flow guiding seat.

5. A method for treating limestone desulfurization wastewater according to claim 4, characterized in that: The upper end of the evaporator ball is provided with a connecting pipe fixedly installed on a fixed plate and connected to the flue gas branch pipe. The interior of the evaporator ball is provided with an inner heating chamber and an outer heat conduction chamber distributed inside and outside. The upper and lower ends of the outer heat conduction chamber are respectively connected to the connecting pipe and the air outlet at the bottom end of the evaporator ball.

6. A method for treating limestone desulfurization wastewater according to claim 5, characterized in that: The upper end of the guide pipe is fixedly installed at the outlet of the evaporator ball, and the lower end thereof extends to the bottom of the discharge straight pipe. The top of the guide pipe is provided with an upper air inlet connected to the outlet, and the bottom of the guide pipe is provided with multiple lower exhaust ports inclined upward.

7. A method for treating limestone desulfurization wastewater according to claim 6, characterized in that: The heat transfer scraper comprises a lower plate body which is rotatably mounted inside the discharge straight pipe and movably arranged with the outer wall of the guide pipe, and an upper plate body which is adapted to the inner wall of the guide seat and the outer wall structure of the evaporation ball is fixed on the upper end of the lower plate body.

8. A method for treating limestone desulfurization wastewater according to claim 7, characterized in that: A rotating gear ring fixedly connected to the outer wall of a plurality of lower sheets is rotatably embedded inside the top end of the discharge straight pipe, and a rotating gear meshing with the rotating gear ring is rotatably driven and installed at the bottom end of the evaporation tower.

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