Filtering type belt dehydration system for flue gas desulfurization

Abstract

The utility model relates to the technical field of flue gas desulfurization, in particular to a filter type belt dehydration system for flue gas desulfurization, which comprises a cyclone subsystem and a belt dehydration subsystem, and the cyclone subsystem comprises a cyclone and a cyclone filtrate pool; the belt dehydration subsystem comprises a dehydrator and a dehydration filtrate tank; a cofferdam drainage pipe of the dehydrator is connected with the cyclone filtrate tank; a wastewater discharge pipe and a return pipe are arranged on the dehydration filtrate tank, the return pipe is connected with the cyclone filtrate tank, switch valves are arranged on the return pipe and the wastewater discharge pipe, and the switch valves are electrically connected with a controller; the absorption tower is provided with a chloride ion on-line detector, the chloride ion on-line detector is electrically connected with the controller, and when the chloride ion on-line detector detects that the chloride ion content is smaller than a preset range, the controller controls the switch valve on the return pipe to be opened. The gypsum dehydration system can solve the problems that the desulfurization efficiency is influenced and the scaling corrosion of equipment is accelerated due to the fact that chloride ions in the system are accumulated quickly due to unreasonable wastewater recycling distribution of the existing gypsum dehydration system.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas desulfurization, in particular to a filtering belt dehydration system for flue gas desulfurization. Background Art

[0002] At present, the most widely used technology for flue gas desulfurization is limestone (or carbide slag)-gypsum wet flue gas desulfurization, which mainly includes slurry preparation system, absorption tower and gypsum dehydration system. The specific principle is: limestone powder is used to make slurry as desulfurization absorbent, and then the slurry is pumped into the absorption tower to fully contact and mix with the flue gas. The sulfur dioxide in the flue gas reacts chemically with the calcium carbonate in the slurry and the oxidizing air blown in. The main by-product after the reaction is gypsum slurry. After the gypsum slurry is pumped out of the absorption tower, it is transported to the gypsum dehydration system, and dehydrated by the gypsum cyclone and vacuum belt dehydrator to form solid gypsum, which can be recycled. Among them, a variety of filtrate wastewaters are generated in the gypsum dehydration system. In order to reduce the water consumption and wastewater treatment costs of the entire system, the filtrate is usually collected and a part of it is reused in the absorption tower; for example, the Chinese utility model patent with announcement number CN218166546U discloses a wet flue gas desulfurization treatment system, which is recovered into a reflux water tank by mixing the slurry at the top of the cyclone and the dehydrated filtrate separated by the belt dehydrator gas-water separator, and a part of the reflux liquid in the reflux water tank is reused in the circulating slurry pool of the absorption tower, and the other part is treated by a wastewater cyclone and discharged as wastewater.

[0003] However, the mixed treatment of the above-mentioned filtrates is not convenient for realizing refined management of the corrosive ion content and wastewater discharge in the reused wastewater. In actual use, corrosive ions such as chloride ions accumulate quickly, which affects the desulfurization efficiency and accelerates the scaling and corrosion of the equipment. In order to balance the desulfurization efficiency and the chloride ion content, on the one hand, the amount of absorption slurry will be increased, and on the other hand, the wastewater discharge will be increased, but this will increase the difficulty and cost of subsequent wastewater treatment. Based on this, the present application provides a filter belt dehydration system for flue gas desulfurization. By classifying and recycling different filtrates, it can not only realize the recycling of wastewater, optimize the total water consumption of the system and the subsequent wastewater treatment volume, but also ensure the quality of the reused wastewater, reduce the accumulation rate of chloride ions and salts, reduce the scaling and corrosion rate of equipment, and better maintain the performance of the slurry in the absorption tower. Utility Model Content

[0004] The utility model provides a filtering belt dehydration system for flue gas desulfurization, which can solve the problem that the existing gypsum dehydration system has unreasonable wastewater reuse distribution, resulting in rapid accumulation of chloride ions in the system, thus affecting the desulfurization efficiency and accelerating scaling and corrosion of equipment.

[0005] This application provides the following technical solutions:

[0006] A filter belt dehydration system for flue gas desulfurization comprises a cyclone subsystem and a belt dehydration subsystem connected in sequence, wherein the cyclone subsystem comprises a gypsum cyclone and a cyclone filtrate pool, wherein the liquid inlet of the gypsum cyclone is connected to the circulating slurry pool of the absorption tower through a pipeline, the bottom flow port of the gypsum cyclone is connected to the feed end of the belt dehydration subsystem through a pipeline, and the top flow port is connected to the cyclone filtrate pool through a pipeline, and the cyclone filtrate pool is provided with two reflux pipelines, one refluxes to the absorption tower, and the other refluxes to the slurry preparation system;

[0007] The belt dehydration subsystem includes a dehydrator, a flushing assembly for flushing the filter cloth of the dehydrator, and a dehydration filtrate pool. The dehydrator is installed on a cofferdam on the ground. The cofferdam is used to collect flushing water, and a filtering assembly for filtering flushing water is arranged inside the cofferdam. A drainage pipe is arranged on the cofferdam, and the drainage pipe is connected to the cyclone filtrate pool. The dehydrator is also connected to an air-water separation assembly, which includes an air-water separator and a water ring vacuum pump.

[0008] The discharge pipe of the gas-water separator is connected to the dewatering filtrate pool, and a wastewater discharge pipe and a reflux pipe are arranged on the dewatering filtrate pool. The drain outlet of the reflux pipe is connected to the cyclone filtrate pool, and switch valves are arranged on the reflux pipe and the wastewater discharge pipe, and the switch valves are electrically connected to the controller; an online chloride ion detector is arranged on the slurry pool of the absorption tower, and the online chloride ion detector is electrically connected to the controller. When the online chloride ion detector detects that the chloride ion content is less than a preset range, the controller controls the switch valve on the reflux pipe to open; when the online chloride ion detector detects that the chloride ion content is greater than the preset range, the controller controls the switch valve on the reflux pipe to close, and controls the switch valve on the wastewater discharge pipe to open.

[0009] Beneficial effects:

[0010] 1. By setting up a cyclone filtrate pool to collect the filtrate at the top of the gypsum cyclone and the flushing water in the dehydrator cofferdam, the wastewater generated in the gypsum dehydration system can be effectively collected. Part of the collected wastewater is used to flow back to the absorption tower, and the other part is returned to the slurry preparation system for slurry preparation, which maximizes the recycling of wastewater and reduces the water consumption and fresh water injection of the entire system.

[0011] 2. Since the filtrate at the top of the cyclone also contains a certain concentration of dissolved salts and corrosive ions, the present application collects the flushing water collected in the dehydrator cofferdam into the cyclone filtrate pool, which can dilute the cyclone filtrate in the cyclone filtrate pool, thereby maintaining the absorber slurry in an appropriate concentration range, maintaining the absorber slurry quality, and ensuring the desulfurization efficiency.

[0012] 3. The gypsum slurry pumped out from the absorption tower slurry pool is first separated and concentrated by a gypsum cyclone, and then deeply dehydrated by a vacuum belt dehydrator. Therefore, the dehydrated filtrate separated by the vacuum belt dehydrator contains the highest concentration of salt and corrosive ions in the gypsum dehydration system. By collecting this part of the wastewater separately, it has been verified that the accumulation rate of chloride ions and salts can be reduced, thereby reducing the corrosion and scaling rate of the equipment and improving the quality of wastewater reuse, compared with all mixing in the cyclone filtrate pool for reuse.

[0013] 4. According to the chloride ion content in the absorption tower, the controller is used to automatically control the reuse and discharge of the wastewater in the dewatering filtrate pool, which can realize refined management of wastewater, improve the reuse rate of wastewater, reduce the total amount of wastewater discharged in the dewatering system and the subsequent wastewater treatment cost, and at the same time better control the accumulation of chloride ions in the system; for example, when the chloride ion online detector detects that the chloride ion content is less than the preset range, the controller controls the switch valve on the reflux pipe to open, so that the wastewater in the dewatering filtrate pool enters the cyclone filtrate pool to improve the utilization rate of the wastewater; when the chloride ion online detector detects that the chloride ion content is greater than the preset range, the controller controls the switch valve on the reflux pipe to close, reduce the utilization of this part of wastewater, reduce the chloride ion accumulation rate, and then control the switch valve on the wastewater discharge pipe through the controller to open, discharge a part of the wastewater, and further control the chloride ion content. Compared with the prior art, the amount of wastewater reuse is increased, the amount of wastewater discharged is reduced, and the control of chloride ions is more flexible, which can ensure that the slurry concentration and chloride ion content in the absorption tower are better stabilized in an appropriate range.

[0014] 5. A filtering component is set inside the cofferdam to initially filter out some of the particles washed down by the flushing water and the insoluble particulate impurities mixed in the production environment, preventing the insoluble particles from entering the subsequent circulation system and causing wear and blockage to the pumps, valves, etc. in the system, thereby reducing the subsequent maintenance costs and difficulty.

[0015] Furthermore, the flushing assembly includes a flushing water pipe and a flushing water tank for flushing the filter cloth and filter cake. The water inlet pipe of the flushing water tank and the water inlet pipe of the water ring vacuum pump are connected to the industrial water pipe, and the discharge pipe of the water ring vacuum pump is connected to the flushing water tank; the outlet pipe of the flushing water tank is connected to the flushing water pipe, and two flushing water pumps are arranged in parallel on the outlet pipe of the flushing water tank.

[0016] Beneficial effects: Fresh water supplied by industrial water pipes is used to rinse the filter cloth and filter cake to ensure the quality of gypsum and the dehydration efficiency of the dehydrator. In addition, the water ring vacuum pump discharges water into the flushing water tank, which can be further utilized. Two parallel flushing water pumps are set up, and one or two can be started according to the flushing needs, or one can be used and the other can be used as a standby to ensure the normal operation of the system.

[0017] Furthermore, the filter assembly includes a filter net, a drainage ditch is arranged in the cofferdam, the drainage ditch is arranged obliquely, the water outlet end of the drainage ditch is connected to the drainage pipe of the cofferdam, and the filter net is arranged obliquely along the length direction of the drainage ditch.

[0018] Beneficial effect: The inclined drainage ditch is set to facilitate the rapid delivery of the flushing water collected in the cofferdam to the cyclone filtrate pool, and the filter screen can be used to block the particulate impurities.

[0019] Furthermore, a baffle is hinged on one side of the filter screen at the water outlet end of the drainage ditch, and the baffle is vertically fixed on the side wall of the cofferdam.

[0020] Beneficial effect: Since the filter screen is set at an angle, it is convenient to filter impurities and collect them at the water outlet; when cleaning is needed, the baffle is flipped from a vertical state to a horizontal state, which is convenient for centralized cleaning of filtered impurities.

[0021] Furthermore, an exhaust hood is also provided at the feed end of the dehydrator.

[0022] Beneficial effects: During the dehydration process of gypsum slurry, especially when the slurry is spread on the belt and begins to be dehydrated, a large amount of fine gypsum dust and moisture may be generated. Setting an exhaust hood at the feed end of the dehydrator can effectively capture this part of dust and moisture, avoid direct discharge into the working environment, and reduce air pollution; at the same time, it can also reduce the accumulation of dust and moisture inside the belt dehydrator to maintain the good operation of the equipment.

[0023] Furthermore, a dechlorination treatment device is also provided at the rear end of the dehydrated filtrate pool, and the dechlorination treatment device includes an ozone generator and a bubbling reactor. The wastewater discharge pipe of the dehydrated filtrate pool is connected to the liquid inlet of the bubbling reactor through a tee pipe, and the drain pipe of the bubbling reactor is connected to the cyclone filtrate pool, and a switch valve is provided on the drain pipe of the bubbling reactor, and the switch valve is electrically connected to the controller.

[0024] Beneficial effects: The dechlorination treatment device can remove the chloride ion content in the dewatering filtrate pool to a certain extent before reuse, which can effectively reduce the accumulation rate of chloride ions in the system, while reducing the difficulty and cost of wastewater treatment; chlorine gas is generated by the reaction of ozone and chloride ions, thereby releasing the chloride ions in the wastewater. The treatment process is simple, and the gypsum dewatering filtrate is dechlorinated at this stage to enhance the dechlorination efficiency and avoid the interference of desulfurization intermediates in the desulfurization slurry on dechlorination.

[0025] Furthermore, it also includes a wastewater cyclone, which is connected to the cyclone filtrate pool through a pipeline, and the bottom flow liquid of the wastewater cyclone is returned to the cyclone filtrate pool, and the top flow port of the wastewater cyclone is connected to the dewatering filtrate pool through a pipeline.

[0026] Beneficial effects: Setting up a wastewater cyclone is beneficial to treating the reused water in the cyclone filtrate pool, further improving the quality of the reused filtrate; discharging the wastewater from the top flow outlet of the wastewater cyclone into the dehydrated filtrate pool is convenient for subsequent dechlorination treatment in the dechlorination treatment device, reducing the difficulty and cost of treating the discharged wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the connection structure of the gypsum slurry dehydration system;

[0028] Figure 2 It is a schematic diagram of the connection structure of the cyclone filtrate tank;

[0029] Figure 3 This is a top view of the dehydrator cofferdam;

[0030] Figure 4 It is a schematic diagram of the connection structure of the dewatering filtrate tank;

[0031] Figure 5 This is a schematic diagram of the connection structure of the dewatering filtrate tank in Example 2;

[0032] Figure 6 This is a schematic diagram of the connection structure of the cyclone filtrate tank in Example 3. DETAILED DESCRIPTION

[0033] The following is further described in detail through specific implementation methods:

[0034] The marks in the drawings of the specification include: cyclone subsystem 1, gypsum cyclone 11, cyclone filtrate pool 12, belt dehydration subsystem 2, cofferdam 20, drain ditch 201, filter screen 202, baffle 203, dehydrator 21, exhaust hood 211, dehydration filtrate pool 22, switch valve 221, flushing water tank 23, flushing water pipe 231, flushing water pump 232, gas-water separator 24, water ring vacuum pump 25, bubbling reactor 31, ozone generator 32, wastewater cyclone 4, absorption tower 100, slurry preparation system 101, wastewater treatment station 200.

[0035] Embodiment 1

[0036] like Figure 1-2 As shown, the filtering belt dehydration system for flue gas desulfurization comprises a cyclone subsystem 1 and a belt dehydration subsystem 2 connected in sequence, the cyclone subsystem 1 comprises a gypsum cyclone 11 and a cyclone filtrate pool 12, the liquid inlet of the gypsum cyclone 11 is connected to the circulating slurry pool of the absorption tower 100 through a pipeline, the bottom flow port of the gypsum cyclone 11 is connected to the feed end of the belt dehydration subsystem 2 through a pipeline, and the top flow port is connected to the cyclone filtrate pool 12 through a pipeline, and the cyclone filtrate pool 12 is provided with two reflux pipelines, one refluxes to the absorption tower 100, and the other refluxes to the slurry preparation system 101;

[0037] like Figure 1 As shown, the belt dehydration subsystem 2 includes a dehydrator 21, a flushing component for flushing the filter cloth of the dehydrator 21, and a dehydration filtrate pool 22. The dehydrator 21 in this embodiment adopts a vacuum belt dehydrator, and an exhaust hood 211 is arranged at the feed end of the dehydrator 21. The exhaust hood 211 can effectively capture the dust and moisture generated at the feed end, reduce air pollution, and reduce the accumulation of dust and moisture inside the vacuum belt dehydrator to maintain the good operation of the equipment; the dehydrator 21 is also connected to a gas-water separation component, and the gas-water separation component includes a gas-water separator 24 and a water ring vacuum pump 25. The liquid inlet of the gas-water separator 24 is connected to the vacuum box of the dehydrator 21 through a pipeline, and the exhaust pipe of the gas-water separator 24 is connected to the water ring vacuum pump 25. The gas is sucked away by the water ring vacuum pump 25, and the filtrate is discharged to the dehydration filtrate pool 22 by the discharge pipe of the gas-water separator 24.

[0038] The dehydrator 21 is installed on the cofferdam 20 on the ground. The cofferdam 20 is used to collect flushing water. A filter assembly for filtering flushing water is arranged inside the cofferdam 20. A drain pipe is arranged on the cofferdam 20. The drain pipe is connected to the cyclone filtrate pool 12. Figure 3 As shown, the filtering assembly includes a filter screen 202, a drainage ditch 201 is arranged in the cofferdam 20, the drainage ditch 201 is arranged along the width direction of the cofferdam 20, and the bottom of the drainage ditch 201 is inclined, and the water outlet end of the drainage ditch 201 is connected to the drainage pipe arranged on the cofferdam 20; the filter screen 202 is inclined along the length direction of the drainage ditch 201, and the cofferdam 20 is provided with a notch on one side of the end of the drainage ditch 201, and the filter screen 202 is hinged with a baffle 203 on one side of the notch of the cofferdam 20, and the baffle 203 is vertically fixed to the side wall of the cofferdam 20 by bolts. When it is necessary to clean impurities on the filter screen 202, the bolts can be removed first, and then the baffle 203 can be flipped from a vertical state to a horizontal state.

[0039] like Figure 1 As shown, the flushing assembly includes a flushing water pipe 231 and a flushing water tank 23 for flushing the filter cloth and filter cake, and a flushing nozzle is provided at the water outlet of the flushing water pipe 231; in this embodiment, the water inlet pipe of the flushing water tank 23 and the water inlet pipe of the water ring vacuum pump 25 are connected with an industrial water pipe, and the water discharge pipe of the water ring vacuum pump 25 is connected with the flushing water tank 23; the water outlet pipe of the flushing water tank 23 is connected with the flushing water pipe 231, and two flushing water pumps 232 are provided in parallel on the water outlet pipe of the flushing water tank 23. Fresh water supplied by the industrial water pipe is used to flush the filter cloth and filter cake to ensure the quality of gypsum and the dehydration efficiency of the dehydrator 21, and the water of the water ring vacuum pump 25 is drained into the flushing water tank 23, so that the water can be further utilized; two parallel flushing water pumps 232 are provided, and one or two can be selected to start according to the flushing demand, or one is used and the other is used as a standby to ensure the normal operation of the system.

[0040] like Figure 4 As shown, the dehydrated filtrate pool 22 is provided with a wastewater discharge pipe and a reflux pipe, the drain outlet of the reflux pipe is connected to the cyclone filtrate pool 12, and the reflux pipe and the wastewater discharge pipe are both provided with a switch valve 221, and the switch valve 221 is electrically connected to a controller. Specifically, the switch valve 221 is an electric valve, and the controller is a PLC controller; the slurry pool of the absorption tower 100 is provided with a chloride ion online detector, and the chloride ion online detector is electrically connected to the controller. When the chloride ion online detector detects that the chloride ion content is less than a preset range (the preset range value can be set according to actual conditions, for example, less than or equal to the chloride ion treatment value), the controller controls the switch valve 221 on the reflux pipe to open, so that the wastewater in the dehydrated filtrate pool 22 flows back to the cyclone filtrate pool 12 for reuse; when the chloride ion online detector detects that the chloride ion content is greater than the preset range, the controller controls the switch valve 221 on the reflux pipe to close, and controls the switch valve 221 on the wastewater discharge pipe to open, so that the wastewater is discharged to the wastewater treatment station 200.

[0041] The present application uses a controller to automatically control the reuse and discharge of wastewater in the dehydration filtrate pool 22 according to the chloride ion content in the absorption tower 100, which can achieve refined management of wastewater, improve the reuse rate of wastewater, reduce the total amount of wastewater discharged in the dehydration system and the subsequent wastewater treatment cost, and at the same time better control the accumulation of chloride ions in the system; for example, when the chloride ion online detector detects that the chloride ion content is less than the preset range, the controller controls the switch valve 221 on the reflux pipe to open, so that the wastewater in the dehydration filtrate pool 22 enters the cyclone filtrate pool 12, so as to improve the utilization rate of wastewater. When the chloride ion online detector detects that the chloride ion content is greater than the preset range, the controller controls the switch valve 221 on the reflux pipe to close, thereby reducing the utilization of this part of wastewater and reducing the chloride ion accumulation rate. Then, the controller controls the switch valve 221 on the wastewater discharge pipe to open, discharge a part of the wastewater, and further control the chloride ion content. Compared with the prior art, the amount of wastewater reuse is increased, the amount of wastewater discharged is reduced, and at the same time, the control of chloride ions is more flexible, which can ensure that the slurry concentration and the chloride ion content in the absorption tower 100 are better stabilized within a suitable range.

[0042] Embodiment 2

[0043] The difference between this embodiment and the first embodiment is that Figure 5As shown, a dechlorination treatment device is also provided at the rear end of the dehydrated filtrate pool 22, and the dechlorination treatment device includes an ozone generator 32 and a bubbling reactor 31. The wastewater discharge pipe of the dehydrated filtrate pool 22 is connected to the liquid inlet of the bubbling reactor 31 through a three-way pipe, and the drain pipe of the bubbling reactor 31 is connected to the cyclone filtrate pool 12, and a switch valve 221 is provided on the drain pipe of the bubbling reactor 31, and the switch valve 221 is electrically connected to the controller. Specifically, the ozone generator 32 adopts a plate-type ozone generator, uses air as a raw material, generates ozone in the plate-type ozone generator, and passes the ozone into the bubbling reactor 31 to generate an oxidation-reduction reaction: O3+2Cl - +H2O=2OH - +O2+Cl2, chlorine is released by bubbling, the chlorine is sent to post-treatment, and the dechlorinated filtrate is pumped into the cyclone filtrate pool 12 for reuse. After removing a part of the chloride ions, the accumulation rate of chloride ions in the system can be further reduced, and the utilization rate of the filtrate wastewater can be improved.

[0044] Embodiment 3

[0045] The difference between this embodiment and the second embodiment is that Figure 6 As shown, it also includes a wastewater cyclone 4, which is connected to the cyclone filtrate pool 12 through a pipeline, and the bottom flow liquid of the wastewater cyclone 4 is returned to the cyclone filtrate pool 12, and the top flow port of the wastewater cyclone 4 is connected to the dewatering filtrate pool 22 through a pipeline; the wastewater cyclone 4 is arranged to be beneficial to the treatment of the reused water in the cyclone filtrate pool 12, and further improve the quality of the reused filtrate; the wastewater at the top flow port of the wastewater cyclone 4 is discharged to the dewatering filtrate pool 22, which is convenient for subsequent dechlorination treatment in the dechlorination treatment device, and reduces the difficulty and cost of treating the discharged wastewater.

[0046] The above is only an embodiment of the utility model. The utility model is not limited to the field involved in this implementation case. The common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the utility model, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. Filter belt dehydration system for flue gas desulfurization, characterized in that: It includes a cyclone subsystem and a belt dehydration subsystem connected in sequence, the cyclone subsystem includes a gypsum cyclone and a cyclone filtrate pool, the liquid inlet of the gypsum cyclone is connected to the circulating slurry pool of the absorption tower through a pipeline, the bottom flow port of the gypsum cyclone is connected to the feed end of the belt dehydration subsystem through a pipeline, and the top flow port is connected to the cyclone filtrate pool through a pipeline. The cyclone filtrate pool is provided with two reflux pipelines, one refluxes to the absorption tower, and the other refluxes to the slurry preparation system; The belt dehydration subsystem includes a dehydrator, a flushing assembly for flushing the filter cloth of the dehydrator, and a dehydration filtrate pool. The dehydrator is installed on a cofferdam on the ground. The cofferdam is used to collect flushing water, and a filtering assembly for filtering flushing water is arranged inside the cofferdam. A drainage pipe is arranged on the cofferdam, and the drainage pipe is connected to the cyclone filtrate pool. The dehydrator is also connected to an air-water separation assembly, which includes an air-water separator and a water ring vacuum pump. The discharge pipe of the gas-water separator is connected to the dewatering filtrate pool, and a wastewater discharge pipe and a reflux pipe are arranged on the dewatering filtrate pool. The drain outlet of the reflux pipe is connected to the cyclone filtrate pool, and switch valves are arranged on the reflux pipe and the wastewater discharge pipe, and the switch valves are electrically connected to the controller; an online chloride ion detector is arranged on the slurry pool of the absorption tower, and the online chloride ion detector is electrically connected to the controller. When the online chloride ion detector detects that the chloride ion content is less than a preset range, the controller controls the switch valve on the reflux pipe to open; when the online chloride ion detector detects that the chloride ion content is greater than the preset range, the controller controls the switch valve on the reflux pipe to close, and controls the switch valve on the wastewater discharge pipe to open.

2. The filter belt dehydration system for flue gas desulfurization according to claim 1 is characterized in that: The flushing assembly includes a flushing water pipe and a flushing water tank for flushing the filter cloth and filter cake. The water inlet pipe of the flushing water tank and the water inlet pipe of the water ring vacuum pump are connected to the industrial water pipe, and the discharge pipe of the water ring vacuum pump is connected to the flushing water tank; the water outlet pipe of the flushing water tank is connected to the flushing water pipe, and two flushing water pumps are arranged in parallel on the water outlet pipe of the flushing water tank.

3. The filter belt dehydration system for flue gas desulfurization according to claim 2 is characterized in that: The filter assembly comprises a filter net, a drainage ditch is arranged in the cofferdam, the drainage ditch is arranged obliquely, the water outlet end of the drainage ditch is connected to the drainage pipe of the cofferdam, and the filter net is arranged obliquely along the length direction of the drainage ditch.

4. The filter belt dehydration system for flue gas desulfurization according to claim 3 is characterized in that: The filter screen is hinged with a baffle on one side of the water outlet end of the drainage ditch, and the baffle is vertically fixed on the side wall of the cofferdam.

5. The filter belt dehydration system for flue gas desulfurization according to claim 4 is characterized in that: The feed end of the dehydrator is also provided with an exhaust hood.

6. The filter belt dehydration system for flue gas desulfurization according to any one of claims 1 to 5, characterized in that: A dechlorination treatment device is also provided at the rear end of the dehydrated filtrate pool, and the dechlorination treatment device includes an ozone generator and a bubbling reactor. The wastewater discharge pipe of the dehydrated filtrate pool is connected to the liquid inlet of the bubbling reactor through a three-way pipe, and the drain pipe of the bubbling reactor is connected to the cyclone filtrate pool, and a switch valve is provided on the drain pipe of the bubbling reactor, and the switch valve is electrically connected to the controller.

7. The filter belt dehydration system for flue gas desulfurization according to claim 6, characterized in that: It also includes a wastewater cyclone, which is connected to a cyclone filtrate pool through a pipeline, and the bottom flow liquid of the wastewater cyclone flows back to the cyclone filtrate pool, and the top flow port of the wastewater cyclone is connected to a dewatering filtrate pool through a pipeline.

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