Thermal power plant desulfurization wastewater discharge treatment process

Abstract

The invention discloses a thermal power plant desulfurization wastewater discharge treatment process, which belongs to the technical field of wastewater treatment, solves the problems of difficult colloidal substance removal, long process route and high treatment cost in the prior art, and comprises the following steps: introducing to-be-treated wastewater into a pretreatment system, adjusting the pH value of the wastewater through the pretreatment system, sequentially adding a coagulant and a coagulant aid to enable suspended solids and colloidal substances in the wastewater to form larger alumen ustum, separating the alumen ustum, introducing the separated alumen ustum into a softening treatment system to obtain softened water, introducing the softened water into a membrane concentration system to generate clear liquid reaching the standard and concentrated saline water, and introducing the concentrated saline water into an evaporative crystallization system or a flue atomization evaporation system. The pH value of the wastewater is adjusted through the pretreatment system, the coagulant and the coagulant aid are added to form alumen ustum, suspended solids and colloidal substances in the wastewater are separated and removed, concentrated saline water is treated through the evaporative crystallization system or the flue atomization evaporation system, the process route is simplified, and the treatment cost is reduced.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment, specifically to a process for treating desulfurization wastewater discharge from thermal power plants. Background Technology

[0002] In the power plant operation sector, the treatment of desulfurization wastewater from thermal power plants is crucial. Thermal power plants generate large amounts of wastewater during operation, especially during wet flue gas desulfurization. With increasingly stringent environmental protection requirements and growing public awareness of water resource conservation, the effective treatment of desulfurization wastewater from thermal power plants has become a key issue in this field. Proper treatment of desulfurization wastewater not only prevents environmental pollution but also enables the recycling of water resources, possessing significant economic and social value. Furthermore, the rational treatment of desulfurization wastewater helps ensure the stable operation of the power plant, reduces the probability of equipment failures due to wastewater corrosion, and improves the plant's production efficiency and safety.

[0003] In existing technologies, treating desulfurization wastewater from thermal power plants typically involves a complex process flow, encompassing multiple treatment steps and equipment. Preliminary sedimentation may begin to remove larger suspended particles. Then, chemical agents are added to adjust the wastewater's pH and remove specific pollutants. Filtration equipment may be used to further remove finer impurities. Additionally, to meet emission standards, multiple advanced treatment processes, including adsorption and ion exchange, may be performed. While these conventional methods can treat desulfurization wastewater to some extent, they require multiple sequential treatment stages, resulting in a lengthy process route, with each stage requiring corresponding equipment.

[0004] However, existing treatment methods have significant drawbacks. Due to their lengthy processes and numerous pieces of equipment, they consume substantial amounts of space. Furthermore, the operation and maintenance of numerous devices, as well as the use of chemicals, significantly increase treatment costs. This high-cost, space-consuming approach hinders the efficient treatment of desulfurization wastewater from thermal power plants and fails to meet the growing environmental and economic demands. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this application provides a process for treating desulfurization wastewater discharge from thermal power plants.

[0006] This application adopts the following technical solution: a process for treating desulfurization wastewater discharge from a thermal power plant, comprising the following steps: S1, pretreatment: the wastewater to be treated is introduced into a pretreatment system, the pH value of the wastewater is adjusted by the pretreatment system, and then coagulant and coagulant aid are added sequentially to form larger flocs from suspended solids and colloidal substances in the wastewater. After separating the flocs, pre-clarified water is obtained; S2, softening treatment: the pre-clarified water obtained in step S1 is introduced into a softening treatment system, and calcium carbonate and magnesium hydroxide precipitates are formed by adding sodium carbonate and / or sodium hydroxide to soften the calcium carbonate. After separation of calcium and magnesium hydroxide precipitates, softened water is obtained; S3, Concentration and reduction treatment: The softened water obtained in step S2 is introduced into a membrane concentration system for filtration and separation to produce qualified clear liquid and concentrated brine; S4, Solidification treatment: The concentrated brine produced in step S3 is introduced into an evaporation crystallization system or a flue gas atomization evaporation system for final disposal; When introduced into an evaporation crystallization system, condensate and crystalline salt are generated through the evaporation and crystallization process; When introduced into a flue gas atomization evaporation system, it is sprayed into the flue through atomizing nozzle and evaporated using the waste heat of the flue gas, so that the salt is discharged together with the fly ash.

[0007] Optionally, the pretreatment system includes a housing, with a feed pipe at the top and a dosing pipe at the bottom. A filter plate is provided on the inner side of the housing, and a plurality of nozzles are provided on the top of the filter plate. The dosing pipe communicates with the plurality of nozzles. The outer wall of the filter plate is fitted with the inner wall of the housing. The filter plate can reciprocate along the height direction of the housing. The dosing pipe is a telescopic elastic tube.

[0008] Optionally, the feed pipe is located above the filter plate, the feed pipe is used to deliver wastewater to be treated into the housing, and the dosing pipe is used to deliver coagulant and / or coagulant aid to the nozzle.

[0009] Optionally, the outer wall of the housing is provided with a pair of groove-shaped mounting shells, and the outer wall of the housing is provided with a pair of sliding grooves. The upper end of the sliding grooves communicates with the top of the housing, and there is a distance between the lower end of the sliding grooves and the bottom of the housing. The pair of mounting shells are respectively and correspondingly covered on the outside of the pair of sliding grooves. One mounting shell is provided with a lead screw, and the other mounting shell is provided with a light rod. Each side of the filter plate is provided with a slider. One slider extends through a sliding groove into one mounting shell and is sleeved on the outside of the lead screw. The other slider extends through another sliding groove into another mounting shell and is sleeved on the outside of the light rod. One slider is threadedly connected to the lead screw, and the other slider is slidably connected to the light rod. The outer side of the mounting shell is also provided with a motor for driving the lead screw to rotate.

[0010] Optionally, a bearing seat is provided on the inner wall of one of the mounting housings, and the lead screw passes through the bearing seat and can rotate within the bearing seat; the end of the guide rod is connected to the inner wall of the other mounting housing and is in a fixed state.

[0011] Optionally, when the slider is moved to the lower end of the groove, the bottom of the filter plate is in contact with the inner bottom of the housing, and a sealing ring is provided between the dosing tube and the housing, and the dosing tube can move in the sealing ring.

[0012] Optionally, the filter plate is provided with a plurality of filter holes, and a plurality of nozzles are provided on the top of the filter plate and located outside the filter holes; the inner wall of the filter holes is provided with a plurality of air chambers, the air chambers are connected to the inner side of the filter holes, a movable tongue plate is provided inside the air chamber, the outer wall of the movable tongue plate is in contact with the inner wall of the air chamber, one side of the movable tongue plate is flush with the opening of the air chamber, the other side of the movable tongue plate is close to the bottom of the air chamber, and a pressure-adjustable driving chamber is formed between the movable tongue plate and the bottom of the movable air chamber; when the air pressure in the driving chamber increases, the movable tongue plate moves toward the inner side of the filter holes, and when the air pressure in the driving chamber decreases, the movable tongue plate moves toward the inner side of the filter holes.

[0013] Optionally, at least two sealing rings are fitted onto the outer wall of the movable tongue plate, and a limiting rope is provided between the movable tongue plate and the bottom of the air chamber.

[0014] Optionally, the filter plate has a plurality of air channels inside, one end of each air channel is connected to a corresponding air chamber, and the other end of each air channel is connected to an air source. The air source supplies air to the air chamber through the air channels and then draws air out.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. By adjusting the pH value of wastewater through a pretreatment system, adding coagulants and coagulant aids to form flocs and then separating them, suspended solids and colloidal substances in wastewater can be removed; 2. The softening system adds sodium carbonate and / or sodium hydroxide to form precipitates and separate them, which can remove calcium and magnesium ions from the water and reduce the hardness of the water; 3. The membrane concentration system performs filtration and separation to produce qualified clear liquid and concentrated brine, achieving concentration and volume reduction. Finally, the concentrated brine is disposed of through an evaporation crystallization system or a flue gas atomization evaporation system, solving the problems of long process routes, high processing costs, and large space occupation in the existing technology. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this application; Figure 2This is a cross-sectional view of the internal structure of the shell. Figure 1 ; Figure 3 This is a cross-sectional view of the internal structure of the shell. Figure 2 ; Figure 4 This is a partial cross-sectional view of the filter plate; Figure 5 yes Figure 4 Reference diagram of the action state; In the diagram: 1. Housing; 11. Feed pipe; 12. Dosing pipe; 13. Slide groove; 2. Filter plate; 21. Slider; 22. Filter hole; 221. Air chamber; 222. Movable tongue plate; 223. Drive chamber; 224. Sealing ring; 225. Limiting rope; 3. Nozzle; 4. Mounting shell; 41. Lead screw; 42. Smooth rod; 43. Bearing seat; 44. Motor. Detailed Implementation

[0017] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0018] like Figure 1-5 As shown, a process for treating desulfurization wastewater from thermal power plants includes pretreatment, softening, concentration and volume reduction, and solidification steps. By sequentially performing these steps, various impurities and pollutants in the desulfurization wastewater from thermal power plants can be gradually removed, enabling the wastewater to meet discharge or recycling standards. This effectively solves the problems of long process routes, high treatment costs, and large site requirements in existing technologies.

[0019] Specifically, in the pretreatment step, the wastewater to be treated is introduced into the pretreatment system. The pretreatment system includes a shell 1, with an inlet pipe 11 at the top and a dosing pipe 12 at the bottom. The inlet pipe 11 is located above the filter plate 2 and is used to transport the wastewater to be treated into the shell 1. The dosing pipe 12 is used to deliver coagulant and / or coagulant aid to the nozzles 3. The filter plate 2 is located inside the shell 1, and several nozzles 3 are located on the top of the filter plate 2. The dosing pipe 12 is connected to several nozzles 3. The outer wall of the filter plate 2 is attached to the inner wall of the shell 1, and the filter plate 2 can move back and forth along the height direction of the shell 1. The dosing pipe 12 has a telescoping elastic tube, so that during the up and down movement of the filter plate 2, the dosing pipe 12 can adaptively expand and contract, thereby preventing the dosing pipe 12 from breaking.

[0020] The filter plate 2 has several filter holes 22, and several nozzles 3 are located on the top of the filter plate 2 and outside the filter holes 22. Multiple air chambers 221 are provided on the inner wall of the filter holes 22, communicating with the inner side of the filter holes 22. A movable tongue plate 222 is provided inside each air chamber 221. The outer wall of the movable tongue plate 222 is fitted against the inner wall of the air chamber 221. One side of the movable tongue plate 222 is flush with the opening of the air chamber 221, and the other side is close to the bottom of the air chamber 221. A pressure-adjustable drive chamber 223 is formed between the movable tongue plate 222 and the bottom of the movable air chamber 221. At least two sealing rings 224 are fitted onto the outer wall of the movable tongue plate 222, and a limiting rope 225 is provided between the movable tongue plate 222 and the bottom of the air chamber 221. The filter plate 2 has several air channels inside. One end of each air channel is connected to a corresponding air chamber 221, and the other ends of each air channel are interconnected and connected to an air source. The air source supplies air to the air chamber 221 through the air channels and then draws air out. When the air source simultaneously supplies gas to several air channels, the air pressure in the drive chamber 223 gradually increases. At this time, the movable tongue plate 222 moves towards the inside of the filter hole 22 under the pushing action of the gas, thereby reducing the inner diameter of the filter hole 22 and enabling filtration. When the air source draws the gas out of the air chamber 221 through several air channels, the air pressure in the drive chamber 223 gradually decreases. At this time, the movable tongue plate 222 moves towards the bottom of the air chamber 221 under the pulling action of the air pressure, thereby restoring the inner diameter of the filter hole 22 to its maximum state and enabling stirring. The sealing ring 224 improves the airtightness between the movable tongue plate 222 and the inner wall of the air chamber 221, thereby ensuring that the movable tongue plate 222 can be driven by adjusting the air pressure in the drive chamber 223. The limiting rope 225 ensures that the movable tongue plate 222 will not detach from the air chamber 221, facilitating the reset of the movable tongue plate 222.

[0021] The outer wall of the housing 1 is provided with a pair of groove-shaped mounting shells 4, and the outer wall of the housing 1 is provided with a pair of sliding grooves 13. The upper end of the sliding grooves 13 communicates with the top of the housing 1, and there is a distance between the lower end of the sliding grooves 13 and the bottom of the housing 1. The pair of mounting shells 4 are respectively and correspondingly covered on the outside of the pair of sliding grooves 13. A lead screw 41 is provided in one mounting shell 4, and a smooth rod 42 is provided in the other mounting shell 4. A slider 21 is provided on both sides of the filter plate 2. One slider 21 extends through a sliding groove 13 into one mounting shell 4 and is sleeved on the outside of the lead screw 41. The other slider 21 extends through another sliding groove 13 into another mounting shell 4 and is sleeved on the outside of the smooth rod 42. One slider 21 is threadedly connected to the lead screw 41, and the other slider 21 is slidably connected to the smooth rod 42. A motor 44 for driving the lead screw 41 to rotate is also provided on the outside of the mounting shell 4. A bearing seat 43 is provided on the inner wall of one mounting shell 4, and the lead screw 41 passes through the bearing seat 43 and can rotate within the bearing seat 43; the end of the smooth rod 42 is connected to the inner wall of another mounting shell 4 and is in a fixed state. When the slider 21 is moved to the lower end of the slide groove 13, the bottom of the filter plate 2 is in contact with the inner bottom of the shell 1, and a sealing ring is provided between the dosing pipe 12 and the shell 1. The dosing pipe 12 can move within the sealing ring, thereby ensuring that the dosing pipe 12 will not interfere when the filter plate 2 moves towards the lowest position.

[0022] In the pretreatment process, the pH value of the wastewater is first adjusted by the pretreatment system, and then coagulants and coagulant aids are added sequentially to form larger flocs from suspended solids and colloidal substances in the wastewater. After separating the flocs, pre-clarified water is obtained. This is because coagulants and coagulant aids can cause tiny particles in the wastewater to aggregate into larger flocs, facilitating subsequent separation operations. The rotation of the lead screw 41 is achieved by the driving action of the motor 44. The lead screw 41 is in a threaded connection with the corresponding slider 21, while the smooth rod 42 is in a sliding connection with the corresponding slider 21. Thus, under the drive of the motor 44, the filter plate 2 connected to the two sliders 21 can reliably reciprocate along the height direction of the housing 1. In the initial state, the filter plate 2 is located at the bottom inner side of the housing 1, and the movable tongue plate 222 is located inside the air chamber 221. At this time, the filter holes 22 on the filter plate 2 are fully open, meaning the filtration accuracy of the filter plate 2 is relatively poor. When the wastewater to be treated is added into the housing 1 through the feed pipe 11, coagulants, flocculants, and other treatment agents can be sprayed into the housing 1 through the dosing pipe 12. Since the nozzle 3 is set towards the top of the housing 1, the treatment agents can be sprayed from top to bottom and tend to fall downwards after being sprayed. This improves the uniformity of the dispersion of the treatment agents in the wastewater and increases the dosing speed of the treatment agents, thereby improving the contact effect between the treatment agents and the wastewater and shortening the reaction time. Furthermore, when the motor 44 drives the filter plate 2 to move up and down, the flocs generated after treatment can pass through the filter holes 22, so that the up and down movement of the filter plate 2 can achieve a stirring effect on the wastewater and improve the reaction efficiency between the treatment agents and the wastewater.

[0023] After the wastewater is treated with the treatment agent and produces a large amount of floc, the filter plate 2 is first driven to the bottom of the inner side of the housing 1. Then, air is supplied to the air chamber 221 through the air source, which increases the pressure in the driving chamber 223. As a result, the movable tongue plate 222 is moved towards the outside of the air chamber 221. Finally, one end of the movable plate is located in the air chamber 221 and the other end is located in the filter hole 22, thereby effectively improving the filtration accuracy of the filter plate 2. In other words, when the movable tongue plate 222 is pushed out to partially enter the filter hole 22, the size of the filter hole 22 becomes smaller, thereby achieving the interception and filtration of floc. When the filter plate 2, which traps alum flocs, moves to the top of the housing 1, the alum flocs can be removed from the filter plate 2 by scraping or rinsing. Then the movable tongue plate 222 retracts, and the filter plate 2 returns to the top of the inner side of the housing 1. During this process, the remaining alum flocs in the wastewater can freely pass through the filter holes 22, ensuring that the filter plate 2 only achieves the filtering effect on the alum flocs when it moves from bottom to top, preventing the alum flocs from being squeezed and intercepted at the bottom of the housing 1.

[0024] Next, a softening treatment is performed. The pre-clarified water obtained in step S1 is introduced into the softening system. Sodium carbonate and / or sodium hydroxide are added to form calcium carbonate and magnesium hydroxide precipitates. After separating the calcium carbonate and magnesium hydroxide precipitates, softened water is obtained. Sodium carbonate and sodium hydroxide can react with calcium and magnesium ions in the water to form precipitates, thereby reducing the hardness of the water.

[0025] Next comes the concentration and reduction process. The softened water obtained in step S2 is introduced into a membrane concentration system for filtration and separation, producing a qualified clear liquid and concentrated brine. The membrane concentration system utilizes the filtration effect of the membrane to concentrate the salt and other impurities in the water, obtaining concentrated brine and qualified clear liquid.

[0026] Finally, a solidification process is performed. The concentrated brine produced in step S3 is introduced into an evaporation crystallization system or a flue gas atomization evaporation system for final disposal. When introduced into the evaporation crystallization system, condensate and crystalline salt are generated through the evaporation and crystallization process. When introduced into the flue gas atomization evaporation system, the brine is sprayed into the flue through atomizer nozzles and evaporated using the waste heat of the flue gas, allowing the salt to be discharged along with the fly ash. This method solidifies the salt in the concentrated brine, meeting environmental emission requirements.

[0027] The implementation principle of this embodiment is as follows: This process, through the rational arrangement of each treatment step and the adoption of a specific pretreatment system, can efficiently treat desulfurization wastewater from thermal power plants. The movable design of the filter plate 2 in the pretreatment system and the function of the movable tongue plate 222 to adjust the size of the filter holes 22 improve the effect and efficiency of pretreatment. The subsequent softening, concentration and volume reduction, and solidification treatment steps work together to gradually remove impurities and salts from the wastewater, greatly shortening the process route, reducing the number of equipment used, and thus reducing treatment costs and space occupation.

[0028] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. A process for treating desulfurization wastewater discharge from thermal power plants, characterized in that, The following steps are included: S1. Pretreatment: The wastewater to be treated is introduced into the pretreatment system. The pH value of the wastewater is adjusted by the pretreatment system. Then, coagulant and coagulant aid are added in sequence to form larger flocs of suspended solids and colloidal substances in the wastewater. After separating the flocs, pre-clarified water is obtained. S2. Softening treatment: The pre-clarified water obtained in step S1 is introduced into the softening treatment system. Sodium carbonate and / or sodium hydroxide are added to form calcium carbonate and magnesium hydroxide precipitates. After separating the calcium carbonate and magnesium hydroxide precipitates, softened water is obtained. S3. Concentration and reduction treatment: The softened water obtained in step S2 is introduced into the membrane concentration system for filtration and separation to produce qualified clear liquid and concentrated brine. S4. Solidification treatment: The concentrated brine produced in step S3 is introduced into the evaporation crystallization system or the flue gas atomization evaporation system for final treatment. When introduced into the evaporation crystallization system, condensate and crystalline salt are generated through the evaporation and crystallization process. When introduced into the flue gas atomization evaporation system, it is sprayed into the flue through the atomizing nozzle and evaporated using the waste heat of the flue gas, so that the salt is discharged together with the fly ash.

2. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 1, characterized in that, The pretreatment system includes a housing (1), with a feed pipe (11) at the top and a dosing pipe (12) at the bottom. A filter plate (2) is provided on the inner side of the housing (1), and a plurality of nozzles (3) are provided on the top of the filter plate (2). The dosing pipe (12) is connected to the plurality of nozzles (3). The outer wall of the filter plate (2) is attached to the inner wall of the housing (1). The filter plate (2) can reciprocate along the height direction of the housing (1). The dosing pipe (12) is a telescopic elastic tube.

3. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 2, characterized in that, The feed pipe (11) is located above the filter plate (2). The feed pipe (11) is used to transport the wastewater to be treated into the housing (1). The dosing pipe (12) is used to transport coagulant and / or coagulant aid to the nozzle (3).

4. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 2, characterized in that, The outer wall of the housing (1) is provided with a pair of groove-shaped mounting shells (4), and the outer wall of the housing (1) is provided with a pair of sliding grooves (13). The upper end of the sliding groove (13) is connected to the top of the housing (1), and there is a distance between the lower end of the sliding groove (13) and the bottom of the housing (1). A pair of mounting shells (4) are respectively and correspondingly covered on the outside of a pair of sliding grooves (13). A lead screw (41) is provided in one mounting shell (4), and a smooth rod (42) is provided in the other mounting shell (4). A slider (21) is provided on both sides of the filter plate (2). One slider (21) extends through a sliding groove (13) into one mounting shell (4) and is sleeved on the outside of the lead screw (41). The other slider (21) extends through another sliding groove (13) into another mounting shell (4) and is sleeved on the outside of the smooth rod (42). One slider (21) is threadedly connected to the lead screw (41), and the other slider (21) is slidably connected to the smooth rod (42). An electric motor (44) for driving the lead screw (41) to rotate is also provided on the outside of the mounting shell (4).

5. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 4, characterized in that, A bearing seat (43) is provided on the inner wall of one of the mounting housings (4), and the lead screw (41) passes through the bearing seat (43) and can rotate within the bearing seat (43); The end of the light rod (42) is connected to the inner wall of the other mounting shell (4) and is in a fixed state.

6. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 4, characterized in that, When the slider (21) moves to the lower end of the groove (13), the bottom of the filter plate (2) is in contact with the inner bottom of the housing (1), and a sealing ring is provided between the dosing tube (12) and the housing (1), and the dosing tube (12) can move in the sealing ring.

7. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 6, characterized in that, The filter plate (2) is provided with a plurality of filter holes (22), and a plurality of nozzles (3) are provided on the top of the filter plate (2) and located outside the filter holes (22). Multiple air chambers (221) are provided on the inner wall of the filter holes (22), and the air chambers (221) communicate with the inner side of the filter holes (22). A movable tongue plate (222) is provided inside each air chamber (221), and the outer wall of the movable tongue plate (222) is in contact with the inner wall of the air chamber (221). One side of the movable tongue plate (222) is in contact with the inner wall of the air chamber (221). The opening of the air chamber (221) is flush with the other side of the movable tongue plate (222) near the bottom of the air chamber (221). An adjustable air pressure driving chamber (223) is formed between the movable tongue plate (222) and the bottom of the movable air chamber (221). When the air pressure in the driving chamber (223) increases, the movable tongue plate (222) moves toward the inside of the filter hole (22). When the air pressure in the driving chamber (223) decreases, the movable tongue plate (222) moves toward the inside of the filter hole (22).

8. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 7, characterized in that, At least two sealing rings (224) are fitted on the outer wall of the movable tongue plate (222), and a limiting rope (225) is provided between the movable tongue plate (222) and the bottom of the air chamber (221).

9. The process for treating desulfurization wastewater discharge from a thermal power plant according to claim 7, characterized in that, The filter plate (2) has several air channels inside. One end of each air channel is connected to a corresponding air chamber (221). The other end of each air channel is connected to each other and then connected to an air source. The air source supplies air to the air chamber (221) through the air channels and then draws air out.

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