A water-saving facility and treatment method for washing chloride ions in desulfurized gypsum in coal-fired thermal power plants

Abstract

The present invention discloses a water-saving facility and treatment method for washing chloride ions of desulfurized gypsum in a coal-fired thermal power plant, which mainly includes three circulating water pools, a stirring pool, a belt scale and a conveyor belt for metering and conveying the desulfurized gypsum to be washed; the positive effect of the present invention is that the application of the three circulating water pools can recycle all the waste water for washing the filter cloth, and the water-saving effect is very significant. Another positive effect of the present invention is that the chloride ion content of the desulfurized gypsum after washing does not exceed 300ppm, which improves the quality of the produced building desulfurized gypsum powder by a very high level, greatly reduces equipment corrosion, and prolongs the service life of the equipment. It can be said that this quality desulfurized gypsum powder can produce various and various categories of desulfurized gypsum dry powder mortar, broadening the field.

Description

Technical Field

[0001] The invention relates to the field of flue gas desulfurization gypsum treatment, and in particular to a desulfurization gypsum water-washing chloride ion water-saving facility and a treatment method for a coal-fired thermal power plant. Background Art

[0002] my country's energy consumption is mainly coal-based, with about 90% of sulfur dioxide, 67% of nitrogen oxides, and 70% of smoke emissions coming from coal combustion. Among them, the most prominent pollution is from flue gas emissions from coal-fired thermal power plants. The state requires coal-fired enterprises, especially coal-fired thermal power plants, to install desulfurization and denitrification equipment, enforce the flue gas emission standards for sulfur dioxide and nitrogen oxides before they can operate, and implement strict dynamic monitoring.

[0003] Flue gas desulfurization gypsum is a byproduct of desulfurization in coal-fired thermal power plants. The chemical composition of desulfurization gypsum is mainly calcium sulfate dihydrate, which is generally higher in purity than natural gypsum. In recent years, the number of manufacturers using flue gas desulfurization gypsum to produce building desulfurization gypsum powder has increased year by year, and the development momentum is extremely active. Due to the different coal quality, desulfurization process and limestone used in various coal-fired thermal power plants, the performance and quality of desulfurization gypsum produced by various power plants are different, but they also have one thing in common, that is, the chloride ion content of desulfurization gypsum in most coal-fired thermal power plants is too high.

[0004] Chloride ions are impurity ions in flue gas desulfurization gypsum. During the combustion of coal, the chlorine in it is converted into hydrogen chloride in the flue gas. It enters the desulfurization system with the flue gas, is absorbed in the absorption tower, and enters the slurry in the form of soluble salts; some chloride ions are brought in by process water. There are many factors that affect the concentration of chloride ions in the sulfur dioxide absorption slurry: chloride ions entering the make-up water, the concentration of hydrogen chloride in the flue gas, and chloride ions removed during the production process.

[0005] Most coal-fired thermal power plants pay great attention to desulfurization, but they pay less attention to the high chloride ion content in the desulfurization gypsum, a byproduct of desulfurization. Therefore, the chloride ion content of desulfurization gypsum in most power plants is very high. The high chloride ion content in desulfurization gypsum has a great impact on the production of building desulfurization gypsum, causing many problems such as yellowing, moisture, sagging, easy corrosion, poor adhesion, etc., which restricts the application and development of building desulfurization gypsum powder; excessive chloride ion will also seriously corrode the desulfurization gypsum powder production equipment and reduce the service life of the production equipment.

[0006] The newly promulgated national standard for flue gas desulfurization gypsum (GB / T37785-2019) sets three levels of chloride ion content for flue gas desulfurization gypsum: the first level has a chloride ion content of 100ppm; the second level has a chloride ion content of 300ppm; and the third level has a chloride ion content of 600ppm. At present, very few flue gas desulfurization gypsums in coal-fired thermal power plants across the country have chloride ion content that can reach the third level (600ppm), and most of them are between 2000 and 3000ppm. The chloride ion content of flue gas desulfurization gypsum in some power plants is between 5000 and 7000ppm. With such a high chloride ion content in desulfurization gypsum, how can we produce high-quality building desulfurization gypsum powder? This is a major problem that needs to be solved urgently.

[0007] At present, in order to improve the quality of desulfurized gypsum and expand the application field and sales channels of desulfurized gypsum, a few domestic building desulfurized gypsum powder manufacturers use water washing to remove excessive chloride ions in desulfurized gypsum. First, the desulfurized gypsum to be washed and water are transported to the slurry mixing tank according to a certain water-to-material ratio, and stirred into a desulfurized gypsum slurry of a certain concentration. Then the slurry is pumped to the slurry distributor on the vacuum filter. The slurry flows evenly on the filter cloth from the slurry distributor. After filtration, the desulfurized gypsum is separated from the filtrate. Most of the chloride ions in the desulfurized gypsum are taken away with the filtrate; the purpose of removing chloride ions in the desulfurized gypsum is achieved; because the filter cloth on the vacuum filter must be washed on both sides with high-pressure water every cycle, otherwise it will affect the filtering effect; the water consumption for washing the filter cloth is very large. Calculated based on 20 tons / hour of water-washed desulfurized gypsum, 10 tons / hour of water is required for slurrying; 12 tons / hour of water is required for washing the filter cloth, and 528 tons of water is consumed in 24 hours. To reduce the amount of water used for washing desulfurized gypsum, we must first solve the problem of recycling the waste water from washing the filter cloth, otherwise water saving will not have a significant effect. Summary of the invention

[0008] The present invention discloses a chloride ion water-saving facility and treatment method for desulfurized gypsum water washing in a coal-fired thermal power plant;

[0009] The purpose of the present invention is to provide a water-saving facility for washing chloride ions of desulfurized gypsum; the present invention is to cast three circulating water pools with reinforced concrete below the vacuum filter, and the capacity of each circulating water pool is 80 to 100 cubic meters. The circulating water pool is mainly used to collect the waste water for washing the filter cloth that can be reused during the production process. The purpose of washing the filter cloth is to use high-pressure water to wash out the fine particles blocking the pores of the filter cloth, so that the filter cloth can filter more smoothly; and the water after washing the filter cloth contains only a very small amount of fine desulfurized gypsum particles that become turbid, and there is no sundry; the clarified water can be used to continue to wash the filter cloth, which can greatly reduce the water consumption for washing desulfurized gypsum, save very precious water resources, and also reduce the burden of sewage discharge, which is beneficial to the country and the people. This is the core of the present invention.

[0010] Another purpose of the present invention is to save water in washing the chloride ions in the desulfurized gypsum while ensuring that the chloride ion content of the desulfurized gypsum after washing does not exceed 300ppm. The present invention is to install two spray rinsing devices above the vacuum filter. The water consumption of the two clean water spray rinsing is not large, but the effect of reducing the chloride ion content in the desulfurized gypsum is very significant. This is the key to the present invention.

[0011] To achieve the above object, the present invention discloses the following technical solution:

[0012] A water-saving facility for washing chloride ions in desulfurized gypsum in a coal-fired thermal power plant, wherein a vacuum filter is installed on the second floor of a workshop, and a wastewater collection pool for washing filter cloth is cast with concrete below the vacuum filter; three concrete-cast circulating water pools, a mixing pool and a slurry pump machine are arranged underground on the first floor of the workshop, a vacuum pump is installed on a concrete-cast platform on the first floor, a gas-liquid separator is installed in the middle of one side of the second-floor filter, a belt scale and a conveyor belt and desulfurized gypsum to be washed are all arranged outside the first-floor workshop, and the washed desulfurized gypsum is scraped off from the end of the filter and falls into a pile of washed desulfurized gypsum 19 on the first floor;

[0013] The invention is characterized in that each of the three circulating water pools has a capacity of 80 to 100 cubic meters, wherein a first pumping pump 12 is installed above the first circulating water pool 1, a second pumping pump 13 is installed above the second circulating water pool 2, and a third pumping pump 14 is installed above the third circulating water pool 3. The water outlets of the three pumping pumps installed on the three circulating water pools are all connected to the pumping and washing filter cloth water pipe and valve 11 on the filter. In addition, the tap water pipe and valve 10 introduced from outside the workshop are respectively connected to the first spray rinsing pipe 21 and the second spray rinsing pipe 22 on the filter. The rinsing pipe 22, the tap water pipe for washing the filter cloth and the valve 17 are connected in sequence. The first circulating water pool water inlet valve 23 is installed at the upper water inlet pipe of the first circulating water pool; the second circulating water pool water inlet valve 24 is installed at the upper water inlet pipe of the second circulating water pool; the third circulating water pool water inlet valve 25 is installed at the upper water inlet pipe of the third circulating water pool. By adjusting the first circulating water pool water inlet valve 23, the second circulating water pool water inlet valve 24 and the third circulating water pool water inlet valve 25, it is controlled to control which circulating water pool the waste water from washing the filter cloth is discharged into.

[0014] The present invention further discloses a method for treating desulfurized gypsum water-washing chloride ion water-saving facilities in a coal-fired thermal power plant, which is characterized by the following steps:

[0015] 1. First, open the water pipe and valve 10 for spraying and rinsing and the water pipe and valve 17 for washing the filter cloth, open the filter cloth transmission system to start washing the filter cloth, and the waste water for washing the filter cloth flows into the mixing tank along the wastewater collection tank floor drain 16 pipeline under the filter. When the water level in the mixing tank 4 reaches 1 / 3 of the depth, turn on the stirring motor and the belt scale and conveyor belt 5 for conveying the desulfurized gypsum 18 to be washed, and the desulfurized gypsum continuously enters the mixing tank to form desulfurized gypsum slurry through stirring. When the slurry in the mixing tank rises to 2 / 3 of the depth of the mixing tank, start to adjust the water inlet valve 26 of the mixing tank to reduce the water inlet, and control the water-to-material ratio of the slurry to 1:2; at this time, open the water inlet valve 23 of the first circulating water tank to discharge a large amount of waste water for washing the filter cloth into the first circulating water tank;

[0016] 2. When the No. 1 circulating water pool 1 is almost full of the waste water for washing the filter cloth, the water inlet valve 24 of the No. 2 circulating water pool 2 is opened, and the water inlet valve 23 of the No. 1 circulating water pool is closed; a large amount of waste water for washing the filter cloth begins to be discharged into the No. 2 circulating water pool 2. At this time, the No. 1 circulating water pool 1 filled with very turbid waste water for washing the filter cloth is left to stand for recycling after the water is clarified;

[0017] 3. When the No. 2 circulating water pool 2 is almost full of the waste water collected for washing the filter cloth, the No. 3 circulating water pool inlet valve 25 of the No. 3 circulating water pool 3 is opened, and the No. 2 circulating water pool inlet valve 24 is closed; a large amount of waste water for washing the filter cloth is discharged into the No. 3 circulating water pool 3. At this time, the waste water for washing the filter cloth in the No. 1 circulating water pool 1 has been clarified. At this time, the tap water pipe for washing the filter cloth and valve 17 are closed first, and then the pumping pipe for washing the filter cloth and valve 11 are opened, and then the No. 1 pumping pump 12 on the No. 1 circulating water pool 1 is opened to continue washing the filter cloth with the clarified waste water for washing the filter cloth in the No. 1 circulating water pool. At this time, the No. 2 circulating water pool 2 filled with very turbid waste water for washing the filter cloth is left to stand for recycling after the water is clarified;

[0018] Fourth, when the No. 3 circulating water pool 3 is almost full of the waste water for washing the filter cloth, the clarified water in the No. 1 circulating water pool 1 is almost emptied, at this time, the No. 1 pumping pump 12 on the No. 1 circulating water pool 1 is closed, the No. 1 circulating water pool water inlet valve 23 of the No. 1 circulating water pool is opened, and the No. 3 circulating water pool water inlet valve 25 of the No. 3 circulating water pool is closed; the No. 2 pumping pump 13 on the No. 2 circulating water pool is opened, and the clarified water of the No. 2 circulating water pool is used to continue washing the filter cloth. At this time, the No. 3 circulating water pool 3 filled with very turbid waste water for washing the filter cloth is left to stand, and the water is recycled after it is clarified; this is repeated, and a large amount of water for washing the filter cloth is collected to continue washing the filter cloth except for a small amount of water put into the stirring tank to dissolve the desulfurized gypsum. When the water in the circulating water pool is reduced, it can be supplemented with tap water.

[0019] The above steps of opening and closing valves and starting the water pump seem very troublesome. However, in the actual production process, installing a programmable interrupt controller PIC (available in the market) can easily complete the above tasks.

[0020] The present invention further discloses a treatment method for water-washing chloride ion water-saving facilities for desulfurized gypsum in coal-fired thermal power plants to ensure that the chloride ion content of desulfurized gypsum after washing does not exceed 300 ppm, which is characterized by the following steps:

[0021] (1) After the slurry is stirred evenly according to a certain water-to-solid ratio, the slurry pump 6 installed below the stirring tank is turned on to pump the slurry to the slurry distributor 8 above the filter. The slurry flows evenly on the filter cloth through the slurry distributor. As the filter cloth moves forward steadily and slowly, the vacuum filtered slurry is separated into solid and liquid. The desulfurized gypsum is above the filter cloth. As the filter cloth moves forward slowly, its water content gradually decreases. A large amount of chloride ions in the desulfurized gypsum are drawn into the gas-liquid separator 9 along with the filtrate. Finally, the filtrate is separated from the gas-liquid separator and placed in the filtrate collection tank. The filtrate is quickly discharged from the floor drain 15 of the filtrate collection tank of the gas-liquid separator along the filtrate discharge pipe 20 into the sewage pool.

[0022] (2) When the desulfurized gypsum on the filter cloth slowly moves forward to the bottom of the first spray rinsing pipe 21, the water curtain formed by the water flowing out of the spray rinsing pipe is evenly sprayed on the desulfurized gypsum. As the filter cloth slowly moves forward, the desulfurized gypsum that has just been soaked by the spray water is drained again; when passing through the second spray rinsing pipe 22, the desulfurized gypsum is sprayed and rinsed again; after two times of clean water spray rinsing, the chloride ion content of the washed desulfurized gypsum does not exceed 300ppm. At this time, the dehydrated desulfurized gypsum continues to move forward with the filter cloth to the end point and is scraped off by the filter cloth scraper and falls into the pile of washed desulfurized gypsum 19.

[0023] The present invention also discloses the application of the treatment method of water-saving facilities for washing desulfurized gypsum in coal-fired thermal power plants to effectively save water and reduce the cost of washing desulfurized gypsum. In particular, the water-saving facilities are used to ensure that the chloride ion content of the desulfurized gypsum after washing does not exceed 300ppm, effectively reduce the chloride ion concentration, and improve the quality of building desulfurized gypsum. The experimental results show that:

[0024] The water consumption of the desulfurized gypsum water-washing chloride ion water-saving facility for coal-fired thermal power plant treatment is only 1 / 3 of that of the conventional method, and the water-saving effect is very significant. The chloride ion content of the desulfurized gypsum after water washing is only 174.66 ppm.

[0025] Compared with the prior art, the present invention discloses a water-washing chloride ion water-saving facility and treatment method for desulfurized gypsum in a coal-fired thermal power plant, which has the following positive effects:

[0026] (1) The chloride ion content of desulfurized gypsum is controlled not to exceed 300ppm, so that the quality of the produced building desulfurized gypsum powder is improved to a very high level. It can be said that this quality desulfurized gypsum powder can be used to produce various types of desulfurized gypsum dry powder mortar, which broadens the application field of desulfurized gypsum.

[0027] (2) Greatly reduce equipment corrosion and extend equipment service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the chloride ion water-saving facility for desulfurization gypsum washing in a power plant:

[0029] 1. No. 1 circulating water pool 2. No. 2 circulating water pool 3. No. 3 circulating water pool

[0030] 4. Mixing tank 5. Belt scale and conveyor belt 6. Slurry pump 7. Vacuum pump

[0031] 8. Slurry distributor 9. Gas-liquid separator 10. Water pipe and valve

[0032] 11. Pumping water pipes and valves for flushing filter cloth 12. No. 1 water pump

[0033] 13. No. 2 pump 14. No. 3 pump

[0034] 15. Floor drain of gas-liquid separator filtrate collection tank 16. Floor drain of wastewater collection tank

[0035] 17. Rinse the filter cloth with water pipes and valves 18. Wash the desulfurized gypsum

[0036] 19. Washed desulfurized gypsum 20. Filtrate discharge pipeline

[0037] 21. First spray rinsing pipe 22. Second spray rinsing pipe

[0038] 23. No. 1 circulating water pool inlet valve 24. No. 2 circulating water pool inlet valve

[0039] 25. Water inlet valve of No. 3 circulating water pool 26. Water inlet valve of mixing tank. DETAILED DESCRIPTION

[0040] The present invention is described below by specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods known to those skilled in the art. In addition, the embodiments should be understood as illustrative rather than limiting the scope of the present invention, and the essence and scope of the present invention are limited only by the claims. For those skilled in the art, various changes or modifications to these embodiments also belong to the protection scope of the present invention without departing from the essence and scope of the present invention.

[0041] Example 1

[0042] A water-saving facility for washing chloride ions in desulfurized gypsum in a coal-fired thermal power plant, wherein a vacuum filter is installed on the second floor of a workshop, and a wastewater collection pool cast with concrete is provided below the vacuum filter, and three circulating water pools, a mixing pool 4 and a slurry pump machine are cast with concrete in the underground of the first floor of the workshop; the vacuum pump is installed on a platform cast with concrete on the first floor, a gas-liquid separator 9 is installed in the middle of one side of the second-floor filter, a belt scale and a conveyor belt 5 and desulfurized gypsum 18 to be washed are all outside the first-floor workshop, and the washed desulfurized gypsum 19 is scraped off from the end of the filter and falls into a pile of washed desulfurized gypsum on the first floor;

[0043] It is characterized in that each of the three circulating water pools has a capacity of 90 cubic meters, wherein a first pumping pump 12 is installed above the first circulating water pool, a second pumping pump 13 is installed above the second circulating water pool, and a third pumping pump 14 is installed above the third circulating water pool. The water outlets of the three pumping pumps installed on the three circulating water pools are all connected to the pumping and washing filter cloth water pipe and valve 11 on the filter. In addition, the tap water pipe and valve 10 introduced from outside the workshop are respectively connected to the first spray rinsing pipe 21 and the second spray rinsing pipe 21 on the filter. The rinsing pipe 22, the water pipe for washing the filter cloth and the valve 17 are connected in sequence. The first circulating water pool water inlet valve 23 is installed at the upper water inlet pipe of the first circulating water pool; the second circulating water pool water inlet valve 24 is installed at the upper water inlet pipe of the second circulating water pool; the third circulating water pool water inlet valve 25 is installed at the upper water inlet pipe of the third circulating water pool. By adjusting the first circulating water pool water inlet valve 23, the second circulating water pool water inlet valve 24 and the third circulating water pool water inlet valve 25, it is controlled to control which circulating water pool the recycled water is discharged into.

[0044] Example 2

[0045] A method for treating desulfurized gypsum water washing chloride ion water saving facilities in coal-fired thermal power plants:

[0046] 1. First, open the water pipe and valve 10 for spraying and rinsing and the water pipe and valve 17 for washing the filter cloth, open the filter cloth transmission system to start washing the filter cloth, and the waste water for washing the filter cloth flows into the mixing tank along the wastewater collection tank floor drain 16 pipeline under the filter. When the water level in the mixing tank reaches 1 / 3 of the depth, turn on the stirring motor and the belt scale and conveyor belt 5 for conveying the desulfurized gypsum 18 to be washed, and the desulfurized gypsum continuously enters the mixing tank to form desulfurized gypsum slurry through stirring. When the slurry in the mixing tank rises to 2 / 3 of the depth of the mixing tank, start to adjust the water inlet valve 26 of the mixing tank to reduce the water inlet, and control the water-to-material ratio of the slurry to 1:2; at this time, open the water inlet valve 23 of the first circulating water tank to discharge a large amount of waste water for washing the filter cloth into the first circulating water tank;

[0047] 2. When the No. 1 circulating water pool is almost full of waste water for washing filter cloth, open the No. 2 circulating water pool water inlet valve 24 on the No. 2 circulating water pool, and close the No. 1 circulating water pool water inlet valve 23; start to discharge a large amount of waste water for washing filter cloth into the No. 2 circulating water pool. At this time, the No. 1 circulating water pool filled with very turbid waste water for washing filter cloth is left to stand for recycling after the water is clarified;

[0048] 3. When the No. 2 circulating water pool is almost full of the waste water collected for washing the filter cloth, open the No. 3 circulating water pool water inlet valve 25 on the No. 3 circulating water pool, and close the No. 2 circulating water pool water inlet valve 24; start to discharge a large amount of waste water for washing the filter cloth into the No. 3 circulating water pool. At this time, the waste water for washing the filter cloth collected in the No. 1 circulating water pool has been clarified. At this time, first close the pipe and valve for washing the filter cloth with tap water, then open the water pipe and gate for pumping the washing filter cloth, and then open the No. 1 pump 12 on the No. 1 circulating water pool, and continue to wash the filter cloth with the clarified waste water for washing the filter cloth collected in the No. 1 circulating water pool. At this time, the No. 2 circulating water pool 2 filled with very turbid waste water for washing the filter cloth is left to stand, and the water is recycled after it is clarified;

[0049] Fourth, when the No. 3 circulating water pool is almost full of the waste water for washing the filter cloth, the clarified water in the No. 1 circulating water pool is almost emptied, then the No. 1 pump on the No. 1 circulating water pool is closed, the No. 1 circulating water pool water inlet valve 23 of the No. 1 circulating water pool is opened, and the No. 3 circulating water pool water inlet valve 25 of the No. 3 circulating water pool is closed; the No. 2 pump 13 on the No. 2 circulating water pool is opened, and the clarified water of the No. 2 circulating water pool is used to continue washing the filter cloth. At this time, the No. 3 circulating water pool filled with very turbid waste water for washing the filter cloth is left to stand, and the water is recycled after it is clarified; this is repeated, and a large amount of water for washing the filter cloth is collected to continue washing the filter cloth except for a small amount of water put into the stirring tank to dissolve the desulfurized gypsum. When the water in the circulating water pool is reduced, it can be supplemented with tap water.

[0050] Example 3

[0051] The treatment method of using the desulfurization gypsum water washing chloride ion water saving facilities of the coal-fired thermal power plant to ensure that the chloride ion content of the desulfurization gypsum after washing does not exceed 300ppm:

[0052] (1) After the slurry is stirred evenly according to a certain water-to-solid ratio, the slurry pump 6 installed below the stirring tank is turned on to pump the slurry to the slurry distributor 8 above the filter. The slurry flows evenly on the filter cloth through the slurry distributor. As the filter cloth moves forward steadily and slowly, the solid-liquid separation of the slurry is achieved through vacuum filtration. The desulfurized gypsum is above the filter cloth. As the filter cloth moves forward slowly, its water content gradually decreases. A large amount of chloride ions in the desulfurized gypsum are drawn into the gas-liquid separator 9 along with the filtrate. Finally, the filtrate is separated from the gas-liquid separator and placed in the filtrate collection tank. The filtrate is quickly discharged from the filtrate collection tank floor drain 15 of the gas-liquid separator along the filtrate discharge pipe 20 into the sewage pool.

[0053] (2) When the desulfurized gypsum on the filter cloth slowly moves forward to the bottom of the first spray rinsing pipe 21, the water curtain formed by the water flowing out of the spray rinsing pipe is evenly sprayed on the desulfurized gypsum. As the filter cloth slowly moves forward, the desulfurized gypsum that has just been soaked by the spray water is drained again; when passing through the second spray rinsing pipe 22, the desulfurized gypsum is sprayed and rinsed again; after two times of clean water spray rinsing, the chloride ion content of the washed desulfurized gypsum does not exceed 300ppm. At this time, the dehydrated desulfurized gypsum reaches the end point as the filter cloth continues to move forward, and is scraped off by the filter cloth scraper and falls into the pile of washed desulfurized gypsum 19.

[0054] Example 4

[0055] 20200811 Chloride ion content of desulfurized gypsum to be washed is 2661.91ppm

[0056] Vacuum filter manufacturer: Huzhou Hezheng Filtration Machinery Co., Ltd.

[0057] Filter capacity: 20 tons / hour 24-hour desulfurization gypsum washing: 480 tons

[0058] Chloride ion content of desulfurized gypsum after washing: 174.66ppm

[0059] 24-hour water consumption: 160 tons

[0060] The specific operations are as follows:

[0061] 1. First, open the water pipe and valve 10 for spray rinsing and the water pipe and valve 17 for washing the filter cloth, open the filter cloth transmission system on the vacuum filter to start washing the filter cloth, and the waste water for washing the filter cloth flows into the mixing tank along the wastewater collection tank floor drain 16 pipeline below the vacuum filter. When the water level in the mixing tank reaches 1 / 3 of the depth, turn on the stirring motor and the belt scale and conveyor belt for conveying the desulfurized gypsum to be washed, and the desulfurized gypsum continuously enters the mixing tank to form desulfurized gypsum slurry through stirring. When the slurry in the mixing tank rises to 2 / 3 of the depth of the mixing tank, start to adjust the mixing tank water inlet valve 26 to reduce the water inlet and control the water-to-material ratio of the slurry to 1:2; open the No. 1 circulating water tank water inlet valve 23 on the No. 1 circulating water tank to allow a large amount of waste water after washing the filter cloth to be discharged into the No. 1 circulating water tank.

[0062] 2. When the No. 1 circulating water pool is almost full of waste water for washing filter cloth, open the No. 2 circulating water pool water inlet valve 24 on the No. 2 circulating water pool, close the No. 1 circulating water pool water inlet valve 23 on the No. 1 circulating water pool; discharge a large amount of waste water for washing filter cloth into the No. 2 circulating water pool. The No. 1 circulating water pool filled with very turbid waste water for washing filter cloth is allowed to stand for clarification before being recycled.

[0063] 3. When the No. 2 circulating water pool is almost full of the waste water collected for washing the filter cloth, open the No. 3 circulating water pool water inlet valve 25 on the No. 3 circulating water pool, and close the No. 2 circulating water pool water inlet valve 24 on the No. 2 circulating water pool; discharge a large amount of waste water for washing the filter cloth into the No. 3 circulating water pool. At this time, the waste water for washing the filter cloth collected in the No. 1 circulating water pool has been clarified. At this time, first close the water pipe and valve 17 for washing the filter cloth, then open the water pipe and gate 11 for pumping the washing filter cloth, and then open the pump 12 on the No. 1 circulating water pool, and continue to wash the filter cloth with the clarified waste water for washing the filter cloth collected in the No. 1 circulating water pool. The No. 2 circulating water pool filled with very turbid waste water for washing the filter cloth is left to stand, and the water is recycled after it is clarified.

[0064] 4. When the No. 3 circulating water pool is almost full of waste water for washing filter cloth, the clarified water in the No. 1 circulating water pool is almost emptied. At this time, the No. 1 pump on the No. 1 circulating water pool is closed, the No. 1 circulating water pool water inlet valve 23 of the No. 1 circulating water pool is opened, and the No. 3 circulating water pool water inlet valve 25 on the No. 3 circulating water pool is closed; the No. 2 pump 13 on the No. 2 circulating water pool is opened, and the clarified water of the No. 2 circulating water pool is used to continue washing the filter cloth. At this time, the No. 3 circulating water pool filled with very turbid waste water for washing filter cloth is left to stand, and the water is recycled after it is clarified; this is repeated, and a large amount of water for washing the filter cloth is collected to continue washing the filter cloth except for a small amount of water put into the stirring tank to dissolve the desulfurized gypsum. When the water in the circulating water pool is reduced, it can be supplemented with tap water.

[0065] This process is repeated over and over again. Except for a small amount of wastewater that is put into the mixing tank to dissolve the desulfurized gypsum, the rest of the wastewater is collected and used to wash the filter cloth. When the water in the circulating water tank is reduced, it can be supplemented with tap water.

[0066] After the slurry is stirred evenly according to a certain water-to-material ratio, the slurry pump 6 installed below the stirring tank is turned on to pump the slurry to the slurry distributor 8 above the vacuum filter. The slurry flows evenly on the filter cloth through the slurry distributor. As the filter cloth continues to move forward steadily and slowly, the slurry is separated from the solid and liquid through vacuum filtration. The desulfurized gypsum is above the filter cloth, and as the filter cloth continues to move forward slowly, its water content gradually decreases. A large amount of chloride ions in the desulfurized gypsum are drawn into the gas-liquid separator 9 along with the filtrate. Finally, the filtrate is separated from the gas-liquid separator and placed in the filtrate collection tank. The filtrate is quickly discharged from the floor drain 15 of the filtrate collection tank along the filtrate discharge pipe 20.

[0067] When the desulfurized gypsum on the filter cloth of the vacuum filter slowly moves to the bottom of the first spray rinsing pipe 21, the water curtain formed by the water flowing out of the spray rinsing pipe is evenly sprayed on the desulfurized gypsum. As the filter cloth slowly moves forward, the desulfurized gypsum just soaked by the spray water is drained again; when passing through the second spray rinsing pipe 22, the desulfurized gypsum is sprayed and rinsed again. In this way, the chloride ion content of the desulfurized gypsum after water washing is 174.66ppm. (24-hour average value)

[0068] Comparison table between the method of the present invention and the conventional method (equipment production capacity 20 tons / hour, 24-hour production results)

[0069]

[0070] Conclusion: From the comparison of the above data, we can see that the equipment is the same, the start-up time is the same, the total amount of water-washed desulfurized gypsum is the same, and the chloride ion content after washing is less than 300ppm. However, the total water consumption (discharge volume) of the two methods is very different. The water consumption of the method of the present invention is only 30% of that of the conventional method, and the water-saving effect is very significant.

Claims

1. A method for treating desulfurized gypsum by washing chloride ions in a coal-fired thermal power plant, characterized in that: A device for washing chloride ions from desulfurized gypsum in a coal-fired thermal power plant, wherein a vacuum filter is installed on the second floor of a workshop, and a wastewater collection pool is cast with concrete below the vacuum filter; three concrete-cast circulating water pools, a mixing pool and a slurry pump are arranged underground on the first floor of the workshop; a vacuum pump is installed on a concrete-cast platform on the first floor, a gas-liquid separator is installed in the middle of one side of the second-floor filter, a belt scale and a conveyor belt and desulfurized gypsum to be washed are all arranged outside the first floor workshop, and the washed desulfurized gypsum is scraped off from the end of the filter and falls into a pile of washed desulfurized gypsum on the first floor; the device is characterized in that the capacity of each of the three circulating water pools is 80 to 100 cubic meters, and a first pumping pump (12) is installed above the first circulating water pool (1), A second pump (13) is installed above the second circulating water pool (2), and a third pump (14) is installed above the third circulating water pool (3). The water outlets of the three pumps installed on the three circulating water pools are all connected to the pumping water pipe and valve (11) on the filter for washing the filter cloth. In addition, the tap water pipe and valve (10) introduced from outside the workshop are respectively connected to the first spray rinsing pipe (21) on the filter, the second spray rinsing pipe (22), and the tap water pipe and valve (17) for washing the filter cloth in sequence. A first circulating water pool inlet valve (23) is installed at the upper water inlet pipe of the first circulating water pool, a second circulating water pool inlet valve (24) is installed at the upper water inlet pipe of the second circulating water pool (2), and a third circulating water pool inlet valve (25) is installed at the upper water inlet pipe of the third circulating water pool (3). By adjusting the first circulating water pool inlet valve (23), the second circulating water pool inlet valve (24), and the third circulating water pool inlet valve (25), control is controlled to which circulating water pool the waste water from washing the filter cloth is discharged. The treatment method is performed according to the following steps:

1. First, open the water pipe and valve (10) for spraying and rinsing and the water pipe and valve (17) for washing the filter cloth, open the filter cloth transmission system to start washing the filter cloth, and the waste water for washing the filter cloth flows into the mixing tank along the waste water collection tank floor drain (16) pipeline below the filter. When the water level in the mixing tank (4) reaches 1 / 3 of the depth, start the mixing motor and the belt scale and conveyor belt (5) for conveying the desulfurized gypsum (18) to be washed, and the desulfurized gypsum continuously enters the mixing tank to form desulfurized gypsum slurry through stirring. When the slurry in the mixing tank rises to 2 / 3 of the depth of the mixing tank, start adjusting the mixing tank water inlet valve (26) to reduce the water inlet amount, and control the water-to-material ratio of the slurry to 1:2; at this time, open the first circulating water tank water inlet valve (23) to allow a large amount of waste water for washing the filter cloth to be discharged into the first circulating water tank; 2. When the first circulating water pool (1) is almost full of the waste water for washing the filter cloth, the water inlet valve (24) of the second circulating water pool (2) is opened, and the water inlet valve (23) of the first circulating water pool is closed; a large amount of waste water for washing the filter cloth begins to be discharged into the second circulating water pool (2). At this time, the first circulating water pool, which is already filled with very turbid waste water for washing the filter cloth, is left to stand for clarification before being recycled; 3. When the waste water collected by the second circulating water pool (2) for washing the filter cloth is almost full, the water inlet valve (25) of the third circulating water pool (3) is opened, and the water inlet valve (24) of the second circulating water pool is closed; a large amount of waste water for washing the filter cloth begins to be discharged into the third circulating water pool (3). At this time, the waste water for washing the filter cloth collected by the first circulating water pool (1) has been clarified. At this time, the pipe and valve (17) for washing the filter cloth with tap water are closed, and then the pipe and valve (11) for pumping the filter cloth are opened. Then, the first pump (12) on the first circulating water pool (1) is opened, and the filter cloth is continuously washed with the clarified waste water for washing the filter cloth collected by the first circulating water pool. At this time, the second circulating water pool (2) filled with very turbid waste water for washing the filter cloth is left to stand until the water is clarified and then recycled; Fourth, when the filter cloth washing wastewater collected in the third circulating water pool (3) is almost full, the clarified water in the first circulating water pool (1) is almost emptied, at this time, the first pumping pump (12) on the first circulating water pool (1) is closed, the first circulating water pool water inlet valve (23) of the first circulating water pool is opened, and the third circulating water pool water inlet valve (25) on the third circulating water pool (3) is closed; the second pumping pump (13) on the second circulating water pool (2) is opened, and the filter cloth is continued to be washed with the clarified filter cloth washing wastewater collected in the second circulating water pool (2). At this time, the third circulating water pool (3) filled with very turbid filter cloth washing wastewater is left to stand, and the water is recycled after it is clarified; this process is repeated, and a large amount of wastewater for washing the filter cloth is collected except for a small amount of wastewater put into the stirring tank to dissolve the desulfurized gypsum, and the rest is continued to wash the filter cloth.

2. A method for treating desulfurized gypsum from a coal-fired thermal power plant by using the desulfurized gypsum water-washing chloride ion device according to claim 1, characterized in that Proceed as follows: (1) After the slurry is stirred evenly according to a certain water-to-solid ratio, the slurry pump (6) installed below the stirring tank is turned on to pump the slurry to the slurry distributor (8) above the filter. The slurry flows evenly on the filter cloth through the slurry distributor. As the filter cloth moves forward steadily and slowly, the solid-liquid separation of the slurry is achieved through true suction filtration. The desulfurized gypsum is above the filter cloth. As the filter cloth moves forward slowly, its water content gradually decreases. A large amount of chloride ions in the desulfurized gypsum are drawn into the gas-liquid separator (9) along with the filtrate. Finally, the filtrate is separated from the gas-liquid separator and placed in the filtrate collection tank. The filtrate is quickly discharged from the gas-liquid separator filtrate collection tank floor drain (15) along the filtrate discharge pipe (20) into the sewage pool. (2) When the desulfurized gypsum on the filter cloth slowly moves forward to the bottom of the first spray rinsing pipe (21), the water curtain formed by the water flowing out of the spray rinsing pipe is evenly sprayed on the desulfurized gypsum. As the filter cloth slowly moves forward, the desulfurized gypsum that has just been soaked by the spray water is drained again; when passing through the second spray rinsing pipe (22), the desulfurized gypsum is sprayed and rinsed again; after two times of clean water spray rinsing, the chloride ion content of the washed desulfurized gypsum does not exceed 300ppm. At this time, the dehydrated desulfurized gypsum continues to move forward with the filter cloth to the end point, is scraped off by the filter cloth scraper and falls into the pile of washed desulfurized gypsum (19).

3. Application of the method for treating desulfurized gypsum with water-washing chloride ion device in coal-fired thermal power plant as claimed in claim 1 in effectively saving water and reducing the cost of water-washed desulfurized gypsum.

4. Application of the method for treating desulfurized gypsum in coal-fired thermal power plants by using the water-washing chloride ion device as described in claim 2 to effectively reduce the concentration of chloride ions and improve the quality of desulfurized gypsum for buildings.

Images