An industrial boiler desulfurized wastewater recovery device

Abstract

This application relates to the field of sewage treatment technology and discloses an industrial boiler desulfurization wastewater recovery device, which includes a triple tank, a heating tank, a vacuum pump, a first-effect crystallization assembly, and a mixing tank. The vacuum pump and the heating tank are connected through a pipeline. The vacuum pump is used to extract boiler wastewater into the heating tank and make it boil. The heating tank is used to provide steam heat source for the first-effect crystallization assembly. The first-effect crystallization assembly is used to evaporate and concentrate the desulfurization wastewater to precipitate sodium sulfate crystals. The mixing tank is used to introduce boiler wastewater. This application uses the boiler wastewater to provide heat for the evaporation and crystallization of sodium sulfate in the desulfurization wastewater, and uses the sodium sulfate obtained by the evaporation and crystallization of the desulfurization wastewater to remove calcium and magnesium ions in the boiler wastewater. Thus, it not only reasonably utilizes the heat of the boiler wastewater, but also reasonably utilizes the sodium sulfate product obtained by the evaporation of the desulfurization wastewater, reduces the cost of using chemicals to treat the boiler wastewater, and saves energy and resources at the same time.

Description

Technical Field

[0001] This application relates to the field of sewage treatment technology, and in particular to an industrial boiler desulfurized wastewater recovery device. Background Art

[0002] During the operation of coal-fired power plants, a large amount of sulfur dioxide emissions will be generated. In order to reduce the emissions of such harmful gases, flue gas desulfurization technology is usually adopted. Common flue gas desulfurization methods include wet method, dry method and semi-dry method, etc. Among them, wet desulfurization is one of the most widely used technologies at present. Its principle is to atomize and spray lime slurry in the desulfurization tower, and react with sulfur dioxide in the flue gas to generate calcium sulfite or calcium sulfate, so as to achieve the purpose of removing sulfur dioxide. However, during the desulfurization process, harmful substances in the desulfurization tower will continuously accumulate and the concentration will increase continuously. In order to reduce the accumulated concentration, reduce the corrosion and blockage of equipment, and at the same time discharge the fly ash accumulated in the flue gas, the desulfurization equipment will regularly discharge a certain amount of desulfurized wastewater.

[0003] Therefore, the desulfurized wastewater has the following characteristics: 1. High suspended solid content. Since the desulfurized wastewater accumulates a lot of fly ash, there are many suspended solids in the wastewater; 2. High inorganic salt content. The main salt ions in the desulfurized wastewater are calcium ions, magnesium ions, sodium ions, chloride ions, sulfate ions and sulfite ions, etc.; 3. The water quality is easy to scale. The contents of calcium ions, magnesium ions and sulfate ions in the desulfurized wastewater are relatively high, and calcium sulfate is often in a supersaturated state, which is very easy to scale; 4. The content of various heavy metals exceeds the standard.

[0004] In the related art, the Chinese utility model patent with the authorization publication number of CN212403716U discloses a desulfurized wastewater recovery and treatment system, which includes a boiler wastewater drainer, a desulfurized wastewater tank, a chemical dosing tank and a softened water processor. The desulfurized wastewater tank is used to store desulfurized wastewater, and the boiler wastewater drainer is used to discharge boiler wastewater into the desulfurized wastewater tank as well. The calcium and magnesium ions in the boiler wastewater are used to react with the sulfites and sulfates in the desulfurized wastewater, so as to remove the sulfites and sulfates in the desulfurized wastewater tank. The chemical dosing tank is used to store alkaline solutions such as calcium hydroxide and sodium hydroxide, which can be transported into the desulfurized wastewater tank to reduce the heavy metal ions in the desulfurized wastewater to produce corresponding hydroxide precipitates. The softened water processor is used to remove the hardness ions in the desulfurized wastewater, mainly calcium and magnesium ions, so as to achieve the purpose of reducing the scaling tendency of the wastewater. Common softening treatment agents include sodium hydroxide plus sodium carbonate or slaked lime plus sodium carbonate. The hydroxide ions and carbonate ions in the agents can react with calcium and magnesium ions to form magnesium hydroxide and calcium carbonate precipitates.

[0005] In view of the above related technologies, the inventors found that there are some problems in this solution: 1. This solution uses a soft water treatment device to remove the calcium and magnesium ions originally contained in the desulfurized wastewater, and then uses the calcium and magnesium ions in the boiler wastewater to react with the sulfites and sulfates in the desulfurized wastewater to remove the sulfites and sulfates in the desulfurized wastewater pool. Although it saves the recovery treatment equipment for boiler wastewater, it will cause a significant increase in the content of calcium and magnesium ions in the desulfurized wastewater, resulting in a significant increase in the consumption of the softening treatment agents put into the soft water treatment device and the alkaline solution transported from the medicine pool. Compared with only treating the calcium and magnesium ions in the desulfurized wastewater, the effect has not become better, but the cost has increased significantly; 2. This solution does not remove other pollutants contained in the boiler wastewater either, but instead makes the pollutant components in the desulfurized wastewater more complex, making the recovery treatment of the desulfurized wastewater more troublesome; 3. Before the boiler wastewater and the desulfurized wastewater react, the boiler wastewater needs to be cooled first, and this part of the heat is wasted. Summary of the Invention

[0006] In order to solve the above problems, the present application provides an industrial boiler desulfurized wastewater recovery device.

[0007] The industrial boiler desulfurized wastewater recovery device provided by the present application adopts the following technical solutions:

[0008] An industrial boiler desulfurized wastewater recovery device includes a triple box, a heating tank, a vacuum pump, a first-effect crystallization assembly, and a mixing box. The triple box is used to precipitate the calcium and magnesium ions, heavy metal ions, and suspended solids in the desulfurized wastewater. The vacuum pump and the heating tank are connected through a pipeline. The vacuum pump is used to extract the boiler wastewater into the heating tank and make it boil. The heating tank is used to provide steam heat source for the first-effect crystallization assembly. The first-effect crystallization assembly is used to evaporate and concentrate the desulfurized wastewater to precipitate sodium sulfate crystals. The mixing box is used to introduce the boiler wastewater.

[0009] By adopting the above technical solutions, after the desulfurized wastewater is introduced into the triple box, a reagent is added to make the calcium and magnesium ions, heavy metal ions, and suspended solids in the desulfurized wastewater flocculate and precipitate. The upper liquid of the clarified desulfurized wastewater enters the first-effect crystallization assembly for evaporation crystallization;

[0010] The vacuum pump is used to extract the air in the heating tank to make the heating tank in a negative pressure state, so as to extract the boiler wastewater into the heating tank. Since the boiler wastewater is in a high-temperature state itself, the vacuum pump continuously extracts the air in the heating tank, reducing the pressure in the heating tank. The boiler wastewater can reach the boiling state under low pressure, thus generating steam, which can provide steam heat source for the first-effect evaporator, recycling the heat of the boiler wastewater, avoiding the waste of this part of heat, and saving energy;

[0011] The desulfurized wastewater can obtain sodium sulfate crystals after evaporation and crystallization in the first-effect crystallization module. At this time, the sodium sulfate crystals are put into the mixing tank, and the boiler wastewater is introduced into the mixing tank. The sodium sulfate crystals dissolve in the boiler wastewater, and the sulfate ions react with the calcium ions and magnesium ions in the boiler wastewater to form calcium sulfate and magnesium sulfate precipitates, thereby removing the calcium and magnesium ions in the boiler wastewater. At the same time, the sodium sulfate product separated from the desulfurized wastewater is reasonably utilized, avoiding waste of resources and reducing the cost of treating calcium and magnesium ions in the boiler wastewater.

[0012] Optionally, a preheating tank is further arranged between the triple box and the first-effect crystallization module. The preheating tank includes a preheating inner tank and a preheating outer tank. The preheating inner tank and the triple box are connected through a pipeline, and the preheating outer tank is used to introduce boiler wastewater.

[0013] By adopting the above technical solution, the upper clear liquid flowing out of the triple box first enters the preheating inner tank, and the boiler wastewater enters the preheating outer tank. Thus, the heat of the boiler wastewater is used to preheat the desulfurized wastewater first, and then the next evaporation and crystallization operation is carried out. On the one hand, the temperature of the desulfurized wastewater before entering the first-effect crystallization module is increased, making it easier to reach the evaporation temperature, accelerating the evaporation and concentration process, and improving the crystallization efficiency; on the other hand, the heat of the boiler wastewater can be reused twice, avoiding waste of the heat of the boiler wastewater and saving energy.

[0014] Optionally, the first-effect crystallization module includes a first-effect evaporator, a first-effect separator, a first-effect forced circulation pump, and a first centrifuge. The preheating inner tank and the shell side of the first-effect evaporator are connected through a pipeline, and a material pump is arranged on the pipeline. The bottom of the first-effect evaporator and the first-effect separator are connected through a pipeline. The first-effect forced circulation pump is used to transport the liquid in the first-effect separator to the first-effect evaporator. The first centrifuge is connected to the bottom of the first-effect separator through a pipeline, and the discharge port of the first centrifuge is connected to the feed port of the mixing tank.

[0015] By adopting the above technical solution, the steam in the heating tank is transported through a pipeline to the shell side of the first-effect evaporator. The desulfurized wastewater in the preheating tank is transported to the first-effect evaporator through a material pump after preheating. The first-effect evaporator evaporates and concentrates the desulfurized wastewater. The gas-liquid mixed desulfurized wastewater is transported through a pipeline to the first-effect separator for gas-liquid separation. The first-effect forced circulation pump sends the liquid separated by the first-effect separator back into the first-effect evaporator for evaporation and concentration again. In this way, the cycle repeats, the desulfurized wastewater continuously crystallizes, and finally a liquid containing a large amount of sodium sulfate crystals is obtained at the bottom of the first-effect separator. The liquid is transported to the first centrifuge for separation of the liquid and sodium sulfate crystals, thereby separating out sodium sulfate crystals and putting them into the mixing tank to react with the boiler wastewater, so that the calcium and magnesium ions in the boiler wastewater settle, thereby reducing the use of chemicals in the treatment of boiler wastewater and reducing the cost. At the same time, the sodium sulfate product separated from the desulfurized wastewater is reasonably utilized, avoiding waste of resources.

[0016] Optionally, the first-effect crystallization assembly further includes a cooling tank, a condenser and a second centrifuge. A material pump is arranged between the cooling tank and the first centrifuge. The cooling tank includes a cooling inner tank and a cooling outer tank. The condenser is used to introduce condensed water into the cooling outer tank. The outlet of the cooling inner tank is connected to the inlet of the second centrifuge through a pipeline, and the outlet of the second centrifuge is also connected to the inlet of the mixing tank.

[0017] By adopting the above technical solution, the mother liquor separated by the first centrifuge is sent to the cooling tank through a material pump. The cooling water provided by the condenser cools the cooling tank to 35 degrees. The sodium sulfate in the mother liquor freezes and crystallizes to obtain a liquid containing a small amount of sodium sulfate crystals, so that the sodium sulfate in the desulfurized wastewater fully crystallizes and precipitates. The liquid after crystallization in the cooling tank enters the second centrifuge, and the centrifuged sodium sulfate crystals are transported to the mixing tank again. After cooling crystallization, more sulfate ions are separated from the desulfurized wastewater, and the calcium and magnesium ions in the boiler wastewater settle more fully, effectively reducing the cost of softening the boiler wastewater.

[0018] Optionally, it further includes a second-effect crystallization assembly. The second-effect crystallization assembly includes a second-effect evaporator, a second-effect separator and a second-effect forced circulation pump. The steam inlet of the shell side of the second-effect evaporator is connected to the steam outlet of the first-effect separator through a pipeline. The bottom of the second-effect evaporator is connected to the second-effect separator through a pipeline. The second-effect forced circulation pump is used to transport the liquid in the second-effect separator to the second-effect evaporator.

[0019] By adopting the above technical solution, the mother liquor separated by the second centrifuge is transported to the second-effect evaporator through a material pump for continuous evaporation and crystallization. The steam separated by the first-effect separator is transported to the second-effect evaporator as the evaporation heat source, so that the steam discharged from the first-effect separator is fully utilized, saving energy. The gas-liquid mixed mother liquor in the second-effect evaporator enters the second-effect separator for gas-liquid separation. The second-effect forced circulation pump sends the liquid separated by the second-effect separator back to the second-effect evaporator for evaporation and concentration again. This cycle repeats, and the desulfurization wastewater continuously crystallizes. Finally, sodium chloride crystals are obtained at the bottom of the second-effect separator, completing the salt separation operation of the desulfurization wastewater.

[0020] Optionally, the steam outlet of the second-effect separator is communicated with the steam inlet of the condenser. The condenser is set as an air-cooled condenser, and the liquid outlet of the condenser is communicated with the water inlet of the cooling outer tank through a pipeline.

[0021] By adopting the above technical solution, the steam discharged from the second-effect separator is transported to the condenser through a pipeline for cooling. After the steam is cooled, it becomes liquid and is discharged from the water outlet of the condenser into the cooling tank, providing cooling water for the cooling tank, so that this part of the water source is reused, and there is no need to separately provide cooling water for the cooling tank, thus saving water resources.

[0022] Optionally, the first-effect crystallization assembly further includes a water collection tank. The water inlet of the water collection tank is communicated with the condensate outlets of the shell sides of the first-effect evaporator and the second-effect evaporator through pipelines, and the water outlet of the water collection tank is communicated with the preheating outer tank through a pipeline.

[0023] By adopting the above technical solution, during the evaporation process, after the steam in the first-effect evaporator and the second-effect evaporator condenses into condensate, its temperature is still relatively high. To avoid wasting this part of the heat, this part of the condensate can be transported to the water collection tank and then to the preheating outer tank, providing a heat source for preheating the desulfurization wastewater and saving energy.

[0024] Optionally, the medicament put into the triple box includes sodium hypochlorite solution.

[0025] By adopting the above technical solution, by putting sodium hypochlorite solution into the triple box, the sulfite ions in the desulfurization wastewater can be oxidized to sulfate ions, so as to obtain more sodium sulfate crystals, increase the number of sulfate ions reacting with the boiler wastewater, and also more fully precipitate the calcium and magnesium ions in the boiler wastewater, effectively reducing the cost of softening the boiler wastewater. At the same time, the sulfite ions in the desulfurization wastewater are also removed and reasonably utilized.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] 1. The desulfurized wastewater can obtain sodium sulfate crystals through evaporation and crystallization in the first-effect crystallization module. At this time, the sodium sulfate crystals are put into the mixing tank, and the boiler wastewater is introduced into the mixing tank. The sodium sulfate crystals dissolve in the boiler wastewater, and the sulfate ions react with the calcium ions and magnesium ions in the boiler wastewater to form calcium sulfate and magnesium sulfate precipitates, thereby removing the calcium and magnesium ions in the boiler wastewater. At the same time, the sodium sulfate product separated from the desulfurized wastewater is reasonably utilized, avoiding resource waste and reducing the cost of treating calcium and magnesium ions in the boiler wastewater;

[0028] 2. The mother liquor separated by the first centrifuge is sent to the cooling tank through a material pump. The cooling water provided by the condenser cools the cooling tank to 35 degrees, and the sodium sulfate in the mother liquor freezes and crystallizes to obtain a liquid material containing a small amount of sodium sulfate crystals, so that the sodium sulfate in the desulfurized wastewater fully crystallizes and precipitates. The liquid material after crystallization in the cooling tank enters the second centrifuge. The centrifuged sodium sulfate crystals are then transported to the mixing tank. After cooling crystallization, more sulfate ions are separated from the desulfurized wastewater, and the calcium and magnesium ions in the boiler wastewater are also more fully precipitated, effectively reducing the cost of softening the boiler wastewater;

[0029] 3. The steam discharged from the second-effect separator is transported through a pipeline to the condenser for cooling. After the steam is cooled, it becomes a liquid and is discharged from the outlet of the condenser to the cooling tank, providing cooling water for the cooling tank, so that this part of the water source is reused and there is no need to provide a separate cooling water source for the cooling tank, thus saving water resources. Description of the Drawings

[0030] Figure 1 is the overall structural schematic diagram of the embodiment of the present application;

[0031] Figure 2 is Figure 1 a partial enlarged view of the cross-sectional view of part A in, mainly used to display the liquid level sensor.

[0032] Description of the Reference Numerals: 1. Triple tank; 11. Neutralization tank; 12. Reaction tank; 13. Flocculation tank; 2. Heat recovery module; 21. Heating tank; 22. Vacuum pump; 23. Inlet water control valve; 24. Liquid level sensor; 25. Preheating tank; 251. Inner preheating tank; 252. Outer preheating tank; 26. Material pump; 27. Outlet valve; 3. First-effect crystallization module; 31. First-effect evaporator; 32. First-effect separator; 33. First-effect forced circulation pump; 34. First centrifuge; 35. Cooling tank; 351. Inner cooling tank; 352. Outer cooling tank; 36. Second centrifuge; 37. Collection tank; 38. Condenser; 4. Mixing tank; 5. Second-effect crystallization module; 51. Second-effect evaporator; 52. Second-effect separator; 53. Second-effect forced circulation pump. Detailed Embodiments

[0033] The following is a further detailed description of the present application in conjunction with Figure 1 and Figure 2 of the present application.

[0034] An embodiment of the present application discloses an industrial boiler desulfurized wastewater recovery device.

[0035] Referring to Figure 1 , an industrial boiler desulfurized wastewater recovery device includes a triple tank 1, a heat recovery component 2, a first-effect crystallization component 3, a mixing tank 4 and a second-effect crystallization component 5. The desulfurized wastewater first enters the triple tank 1 for pretreatment, and by adding chemicals, calcium ions, magnesium ions and heavy metal ions in the desulfurized wastewater are made to form precipitates. The clarified desulfurized wastewater then enters the first-effect crystallization component 3. The heat recovery component 2 is used to recover the heat of the boiler wastewater and supply it to the first-effect crystallization component 3, so that the desulfurized wastewater can crystallize and separate in the first-effect crystallization component 3, thereby obtaining sodium sulfate crystals and mother liquor. On the other hand, the boiler wastewater is cooled. The sodium sulfate crystals are sent to the mixing tank 4, and the cooled boiler wastewater is also transported to the mixing tank 4. At this time, the sodium sulfate crystals dissolve in the boiler wastewater, and sulfate ions react with calcium ions and magnesium ions in the boiler wastewater to form precipitates, thereby removing calcium ions and magnesium ions in the boiler wastewater. The mother liquor continues to enter the second-effect crystallization component 5, and the second-effect crystallization component 5 continues to evaporate and crystallize the mother liquor, and at this time, sodium chloride crystals can be obtained, completing the salt separation process.

[0036] Referring to Figure 1 , the triple tank 1 includes a neutralization tank 11, a reaction tank 12 and a flocculation tank 13. The desulfurized wastewater first enters the neutralization tank 11, and alkaline substances such as lime milk are added to the neutralization tank 11 to adjust the pH value of the desulfurized wastewater to above 9.0. In an alkaline environment, calcium ions, magnesium ions and most heavy metals form slightly soluble hydroxides and precipitate from the wastewater. In addition, for the convenience of subsequent crystallization treatment, sodium hypochlorite solution can be added to the neutralization tank 11 to oxidize sulfite ions into sulfate ions. The upper-layer liquid separated in the neutralization tank 11 flows into the reaction tank 12, and organic sulfur is added to the reaction tank 12 to remove the remaining heavy metals that cannot precipitate in the form of hydroxides in the form of sulfide precipitates. At the same time, a coagulant is added to accelerate the sedimentation of the compound particles in a suspended state and form a solid flocculation structure. Then the upper-layer liquid separated from the reaction tank 12 flows into the flocculation tank 13, and a coagulant aid is added to the flocculation tank 13, and a flocculation reaction is carried out under low-speed stirring to promote the formation of a larger flocculation state of the solid flocculation structure. Under the action of gravity, the flocs deposit at the bottom and are concentrated into sludge by gravity for subsequent treatment, and the clarified wastewater in the upper part is transported to the first-effect crystallization component 3 for crystallization.

[0037] Referring to Figure 1 and Figure 2, the heat recovery component 2 includes a heating tank 21. A pipeline is connected to the bottom feed inlet of the heating tank 21 for extracting boiler wastewater. An inlet water control valve 23 is installed on the pipeline. A vacuum pump 22 is connected to the top air extraction port of the heating tank 21 through a pipeline for extracting the air in the heating tank 21 to make the inside of the heating tank 21 in a negative pressure state, so as to extract the boiler wastewater into the heating tank 21. A liquid level sensor 24 is installed in the heating tank 21. The liquid level sensor 24 is electrically connected to the inlet water control valve 23. The liquid level sensor 24 is used to monitor the liquid level in the heating tank 21 and control the opening and closing of the inlet water control valve 23. When the liquid level in the heating tank 21 reaches the specified position, the liquid level sensor 24 controls the inlet water control valve 23 to close. At this time, the air in the heating tank 21 is continuously extracted. Since the boiler wastewater itself is in a high-temperature state, when the pressure in the heating tank 21 decreases, the boiler wastewater can reach the boiling state under the low-pressure state, so steam is generated. The top air outlet of the heating tank 21 is connected to the first-effect crystallization component 3 through a pipeline for transporting the steam to the first-effect crystallization component 3 to provide a heat source for it, thereby recycling the heat of the boiler wastewater, avoiding the waste of this part of heat, and saving energy.

[0038] Refer to Figure 1 , the heat recovery component 2 further includes a preheating tank 25. The preheating tank 25 includes a preheating inner tank 251 and a preheating outer tank 252. A material pump 26 is arranged between the flocculation tank 13 and the preheating tank 25. The top water outlet of the flocculation tank 13 is connected to the inlet of the material pump 26 through a pipeline, and the top water inlet of the preheating inner tank 251 is connected to the outlet of the material pump 26 through a pipeline. The supernatant in the flocculation tank 13 is pumped into the preheating tank 25 through the material pump 26. A pipeline is connected to the top water inlet of the preheating outer tank 252 for extracting boiler wastewater. The boiler wastewater enters between the preheating outer tank 252 and the preheating inner tank 251 to preheat the desulfurized wastewater in the preheating inner tank 251. At the same time, the bottom of the heating tank 21 is also connected to the top water inlet of the preheating outer tank 252 through a pipeline, and an outlet valve 27 is installed on the pipeline. When the outlet valve 27 is opened, the remaining boiler wastewater in the heating tank 21 also enters the preheating outer tank 252 to preheat the desulfurized wastewater.

[0039] Refer to Figure 1, the first-stage crystallization assembly 3 includes a first-stage evaporator 31, a first-stage separator 32, a first centrifuge 34, a cooling tank 35 and a second centrifuge 36. A material pump 26 is also provided between the preheating tank 25 and the first-stage evaporator 31. The bottom discharge port of the preheating inner tank 251 is connected to the water inlet of the material pump 26, and the top liquid inlet of the first-stage evaporator 31 is connected to the water outlet of the material pump 26 through a pipeline. The desulfurized wastewater is pumped into the heat exchange tubes of the first-stage evaporator 31 by the material pump 26. The steam outlet provided at the top of the heating tank 21 is connected to the steam inlet of the shell side of the first-stage evaporator 31 through a pipeline. The steam enters the shell side of the first-stage evaporator 31 to heat the desulfurized wastewater in the first-stage evaporator 31 to make it in a steam state. After partial evaporation of the desulfurized wastewater, the wastewater in a liquid state flows into the bottom of the first-stage evaporator 31. The bottom discharge port of the first-stage evaporator 31 is connected to the bottom feed port of the first-stage separator 32 through a pipeline, and the gas-liquid mixed desulfurized wastewater enters the first-stage separator 32 for gas-liquid separation. A first-stage forced circulation pump 33 is provided between the first-stage separator 32 and the first-stage evaporator 31. The feed port of the first-stage forced circulation pump 33 is connected to the bottom liquid outlet of the first-stage separator 32 through a pipeline, and the discharge port of the first-stage forced circulation pump 33 is connected to the top liquid inlet of the first-stage evaporator 31 through a pipeline, so as to send the liquid separated by the first-stage separator 32 into the first-stage evaporator 31 again for evaporation and concentration. In this way, the desulfurized wastewater is continuously crystallized, and finally a liquid containing a large amount of sodium sulfate crystals is obtained at the bottom of the first-stage separator 32. The liquid is sent to the first centrifuge 34 through the material pump 26 for separation of the liquid and sodium sulfate crystals.

[0040] Refer to Figure 1 , the separated sodium sulfate crystals are sent into the mixing tank 4, and the separated mother liquor is sent to the cooling tank 35 through the material pump 26. The cooling tank 35 includes a cooling inner tank 351 and a cooling outer tank 352. The cooling outer tank 352 cools the mother liquor to 35 degrees, so that the sodium sulfate in the mother liquor freezes and crystallizes to obtain a liquid containing a small amount of sodium sulfate crystals. The bottom discharge port of the cooling tank 35 is connected to the top feed port of the second centrifuge 36 through a pipeline. The liquid after crystallization in the cooling tank 35 enters the second centrifuge 36, and the obtained sodium sulfate crystals are transported into the mixing tank 4. The mother liquor separated by the second centrifuge 36 enters the second-stage crystallization assembly 5 to continue evaporation and crystallization.

[0041] Refer to Figure 1, the sodium sulfate crystals separated from the first centrifuge 34 and the second centrifuge 36 are both transported to the mixing tank 4. The boiler wastewater after being heated in the preheating tank 25 is also transported to the mixing tank 4 through the material pump 26. At this time, the heat in the boiler wastewater has been absorbed by the desulfurized wastewater, and the temperature of the boiler wastewater drops. The sodium sulfate crystals dissolve in the boiler wastewater, and the sulfate ions react with the calcium ions and magnesium ions in the boiler wastewater to form calcium sulfate and magnesium sulfate precipitates, thereby removing the calcium and magnesium ions in the boiler wastewater. At the same time, the sodium sulfate product separated from the desulfurized wastewater is reasonably utilized, avoiding resource waste and reducing the cost of treating calcium and magnesium ions in the boiler wastewater.

[0042] Refer to Figure 1 , the second-effect crystallization assembly 5 includes a second-effect evaporator 51 and a second-effect separator 52. The steam outlet at the heating tank 21 is connected to the steam inlet at the shell side of the second-effect evaporator 51 through a pipeline. The steam outlet at the top of the first-effect separator 32 is also connected to the steam inlet at the shell side of the second-effect evaporator 51 through a pipeline. Both the heating tank 21 and the first-effect separator 32 provide steam for the second-effect evaporator 51. The mother liquor separated from the second centrifuge 36 enters the second-effect evaporator 51 through the material pump 26, and the second-effect evaporator 51 continues to evaporate and concentrate the mother liquor. The bottom discharge port of the second-effect evaporator 51 is connected to the bottom feed port of the second-effect separator 52 through a pipeline. The gas-liquid mixed mother liquor enters the second-effect separator 52 for gas-liquid separation. A second-effect forced circulation pump 53 is provided between the second-effect separator 52 and the second-effect evaporator 51. The feed port of the second-effect forced circulation pump 53 is connected to the bottom liquid outlet of the second-effect separator 52 through a pipeline, and the discharge port of the second-effect forced circulation pump 53 is connected to the top liquid inlet of the second-effect evaporator 51 through a pipeline, so as to send the liquid separated by the second-effect separator 52 into the second-effect evaporator 51 again for evaporation and concentration. In this way, the desulfurized wastewater is continuously crystallized, and finally sodium chloride crystals are obtained at the bottom of the second-effect separator 52.

[0043] Refer to Figure 1 , the first-effect crystallization assembly 3 further includes a water collection tank 37. During the evaporation process, after the steam in the first-effect evaporator 31 and the second-effect evaporator 51 condenses into condensed water, its temperature is still relatively high. To avoid wasting this part of the heat, pipelines are connected between the condensed water outlets at the bottom of the shell sides of the first-effect evaporator 31 and the second-effect evaporator 51 and the top water inlet of the water collection tank 37. The bottom water outlet of the water collection tank 37 is also connected to the water inlet of the preheating outer tank 252. The condensed water collected in the water collection tank 37 is transported to the preheating outer tank 252 through the material pump 26 to provide a heat source for preheating the desulfurized wastewater.

[0044] Refer to Figure 1, the first-effect crystallization assembly 3 further includes a condenser 38, which is configured as an air-cooled condenser 38. The steam discharged from the second-effect separator 52 is transported through a pipeline into the condenser 38 for cooling. After the steam is cooled, it becomes a liquid and is discharged from the water outlet of the condenser 38. The water outlet of the condenser 38 is connected to the water inlet of the cooling outer tank 352 through a pipeline to provide cooling water for the cooling tank 35, so that this part of the water source can be reused, and there is no need to separately provide a cooling water source for the cooling tank 35, thus saving water resources. This part of the water source is the water source after pretreatment and evaporation and meets the discharge standard. After being used in the cooling tank 35, it can be discharged from the drain outlet at the bottom of the cooling tank 35 or provided as a water source for the boiler equipment.

[0045] The implementation principle of an industrial boiler desulfurization wastewater recycling device according to an embodiment of the present application is as follows: The desulfurization wastewater is first transported to the triple box 1, and chemicals are sequentially added to the triple box 1 to form flocculent precipitates of calcium and magnesium ions, heavy metal ions, and suspended solids in the desulfurization wastewater, and sodium hypochlorite solution is added to oxidize sulfite ions into sulfate ions for subsequent crystallization treatment. The clarified upper liquid of the triple box 1 is transported to the preheating inner tank 251 through the material pump 26. A part of the boiler wastewater is transported to the preheating outer tank 252 through a pipeline to preheat the desulfurization wastewater in the preheating tank 25.

[0046] The vacuum pump 22 is turned on to make the heating tank 21 in a negative pressure state, so as to pump the boiler wastewater into the heating tank 21. When the pumping reaches the specified liquid level, the liquid level sensor 24 controls the inlet water control valve 23 to close. At this time, the air in the heating tank 21 is continuously pumped. Since the boiler wastewater itself is in a high-temperature state, when the pressure in the heating tank 21 decreases, the boiler wastewater can reach the boiling state under the low-pressure state, so steam is generated. The remaining boiler wastewater in the heating tank 21 also enters the preheating outer tank 252 to preheat the desulfurization wastewater.

[0047] The steam is transported through a pipeline into the shell side of the first-effect evaporator 31. The desulfurization wastewater in the preheating tank 25 is transported into the first-effect evaporator 31 through the material pump 26 after being preheated. The first-effect evaporator 31 evaporates and concentrates the desulfurization wastewater. The gas-liquid mixed desulfurization wastewater is transported through a pipeline into the first-effect separator 32 for gas-liquid separation. The steam in the first-effect separator 32 enters the shell side of the second-effect evaporator 51 as the heat source for the second-effect evaporation. The first-effect forced circulation pump 33 sends the liquid separated by the first-effect separator 32 back into the first-effect evaporator 31 for evaporation and concentration again. In this way, the desulfurization wastewater is continuously crystallized, and finally a liquid containing a large amount of sodium sulfate crystals is obtained at the bottom of the first-effect separator 32. The liquid is sent to the first centrifuge 34 through the material pump 26 for separating the liquid and the sodium sulfate crystals.

[0048] The sodium sulfate crystals separated by the first centrifuge 34 are sent into the mixing tank 4, and the mother liquor obtained by separation is sent into the cooling tank 35 through the material pump 26. The cooling water provided by the condenser 38 is used to cool the cooling tank 35 to 35 degrees Celsius, and the sodium sulfate in the mother liquor freezes and crystallizes to obtain a liquid material containing a small amount of sodium sulfate crystals. The liquid material after crystallization in the cooling tank 35 enters the second centrifuge 36, and the sodium sulfate crystals obtained by centrifugation are transported into the mixing tank 4. After the boiler wastewater in the preheating tank 25 provides heat, its temperature drops. At this time, it is transported into the mixing tank 4 through the material pump 26 again. The sodium sulfate crystals dissolve in the boiler wastewater, and the sulfate ions react with the calcium ions and magnesium ions in the boiler wastewater to form calcium sulfate and magnesium sulfate precipitates, thereby removing the calcium and magnesium ions in the boiler wastewater. At the same time, the sodium sulfate product separated from the desulfurization wastewater is reasonably utilized, avoiding waste of resources and reducing the cost of treating calcium and magnesium ions in the boiler wastewater.

[0049] The mother liquor separated by the second centrifuge 36 is transported into the second-effect evaporator 51 through the material pump 26 for continuous evaporation and crystallization. The steam separated by the first-effect separator 32 is transported into the second-effect evaporator 51 as the evaporation heat source. At the same time, the heating tank 21 also provides steam for the second-effect evaporator 51. The gas-liquid mixed mother liquor in the second-effect evaporator 51 enters the second-effect separator 52 for gas-liquid separation. The second-effect forced circulation pump 53 sends the liquid separated by the second-effect separator 52 back into the second-effect evaporator 51 for evaporation and concentration. This process is repeated, and the desulfurization wastewater continuously crystallizes. Finally, sodium chloride crystals are obtained at the bottom of the second-effect separator 52.

[0050] The steam discharged from the second-effect separator 52 is transported through a pipeline into the condenser 38 for cooling. After the steam is cooled, it becomes a liquid and is discharged from the outlet of the condenser 38 into the cooling tank 35, providing cooling water for the cooling tank 35, enabling this part of the water source to be reused and eliminating the need to separately provide cooling water for the cooling tank 35, thereby saving water resources.

[0051] During the evaporation process, after the steam in the first-effect evaporator 31 and the second-effect evaporator 51 condenses into condensed water, its temperature is still relatively high. To avoid waste of this part of the heat, this part of the condensed water can be transported into the water collection tank 37 and then through the water pump into the outer preheating tank 252 to provide a heat source for preheating the desulfurization wastewater.

[0052] The above are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. An industrial boiler desulfurized wastewater recovery device, characterized in that: It includes a triple box (1), a heating tank (21), a vacuum pump (22), a first-effect crystallization assembly (3), and a mixing box (4). The triple box (1) is used to precipitate calcium and magnesium ions, heavy metal ions, and suspended solids in the desulfurized wastewater. The vacuum pump (22) and the heating tank (21) are connected by a pipeline. The vacuum pump (22) is used to pump boiler wastewater into the heating tank (21) to make it boil. The heating tank (21) is used to provide steam heat source for the first-effect crystallization assembly (3). The first-effect crystallization assembly (3) is used to evaporate and concentrate the desulfurized wastewater to precipitate sodium sulfate crystals. The mixing box (4) is used to introduce boiler wastewater; The first-effect crystallization assembly (3) includes a first-effect evaporator (31), a first-effect separator (32), a first-effect forced circulation pump (33), a first centrifuge (34), a cooling tank (35), a condenser (38), and a second centrifuge (36). The discharge port of the first centrifuge (34) is connected to the feed port of the mixing box (4). A material pump (26) is provided between the cooling tank (35) and the first centrifuge (34). The cooling tank (35) includes a cooling inner tank (351) and a cooling outer tank (352). The condenser (38) is used to introduce condensed water into the cooling outer tank (352). The discharge port of the cooling inner tank (351) is connected to the feed port of the second centrifuge (36) by a pipeline. The discharge port of the second centrifuge (36) is also connected to the feed port of the mixing box (4); It further includes a second-effect crystallization assembly (5). The second-effect crystallization assembly (5) includes a second-effect evaporator (51), a second-effect separator (52), and a second-effect forced circulation pump (53). The steam inlet of the shell side of the second-effect evaporator (51) is connected to the steam outlet of the first-effect separator (32) by a pipeline. The bottom of the second-effect evaporator (51) and the second-effect separator (52) are connected by a pipeline. The second-effect forced circulation pump (53) is used to transport the liquid in the second-effect separator (52) into the second-effect evaporator (51).

2. The industrial boiler desulfurized wastewater recovery device according to claim 1, wherein: A preheating tank (25) is further provided between the triple box (1) and the first-effect crystallization assembly (3). The preheating tank (25) includes a preheating inner tank (251) and a preheating outer tank (252). The preheating inner tank (251) and the triple box (1) are connected by a pipeline. The preheating outer tank (252) is used to introduce boiler wastewater.

3. The industrial boiler desulfurized wastewater recovery device according to claim 2, wherein: The preheating inner tank (251) and the shell side of the first-effect evaporator (31) are connected by a pipeline, and a material pump (26) is provided on the pipeline. The bottom of the first-effect evaporator (31) and the first-effect separator (32) are connected by a pipeline. The first-effect forced circulation pump (33) is used to transport the liquid in the first-effect separator (32) into the first-effect evaporator (31). The first centrifuge (34) is connected to the bottom of the first-effect separator (32) by a pipeline.

4. An industrial boiler desulfurized wastewater recovery device according to claim 1, characterized in that: The steam outlet of the secondary effect separator (52) is communicated with the steam inlet of the condenser (38). The condenser (38) is provided as an air-cooled condenser (38). The liquid outlet of the condenser (38) is communicated with the water inlet of the cooling outer tank (352) through a pipeline.

5. The recovery device for desulfurized waste water of an industrial boiler according to claim 1, wherein: The primary effect crystallization assembly (3) further includes a water collection tank (37). The water inlet of the water collection tank (37) is communicated with the shell-side condensate outlets of the primary effect evaporator (31) and the secondary effect evaporator (51) through pipelines. The water outlet of the water collection tank (37) is communicated with the preheating outer tank (252) through a pipeline.

6. The recovery device for desulfurized waste water of an industrial boiler according to claim 1, characterized in that: The medicament put into the triple box (1) includes sodium hypochlorite solution.

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