Flue gas waste heat concentration device for desulfurization wastewater zero discharge

Abstract

The utility model relates to a kind of for desulfurization wastewater zero discharge flue gas waste heat concentration equipment, the equipment, including concentration device, wastewater circulating pump, wastewater clarifier and thick slurry delivery pump, concentration device is divided into wastewater flow-through area, spraying area and demisting area from bottom to top, wastewater flow-through area bottom is divided into two ways after wastewater circulating pump, one way is communicated with the top of spraying area;Another way is communicated with wastewater clarifier;Spraying area top is equipped with spray pipe, lower portion is equipped with flue gas inlet;Wastewater clarifier is communicated with wastewater flow-through area by thick slurry delivery pump.Cancelling the traditional wastewater storage area and stirring measure in concentration device, reduce overall height;Wastewater in wastewater flow-through area carries out full-flow high-speed circulation, can realize the strong disturbance of slurry under the condition that stirring measure is not needed;Slurry discharged from concentration device is treated after thick slurry clarifier, thick slurry and clean water are treated separately, improve the flexibility of process equipment operation, reduce the risk of deposition and scale in thick slurry delivery pipeline.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment, specifically to a waste heat concentration device for zero-emission flue gas from desulfurization wastewater. Background Technology

[0002] The development and advancement of zero-discharge technology for desulfurization wastewater stems from the dual demands of the thermal power industry under environmental pressure and resource constraints. Against the backdrop of water scarcity, in a plant-wide wastewater zero-discharge water balance system based on the design principle of "high-quality water used optimally, low-quality water used sparingly," desulfurization wastewater, as the terminal component of the entire plant's water system, has become the most critical link in achieving zero-discharge. With increasingly stringent national requirements for salt content and heavy metal indicators in industrial wastewater discharge, "zero discharge" has become a mandatory requirement for thermal power plants to meet environmental standards, making the selection of zero-discharge technology for desulfurization wastewater crucial.

[0003] Currently, zero discharge of limestone-gypsum wet desulfurization wastewater mainly adopts either a low-temperature flue gas waste heat evaporation concentration and reduction process + high-temperature flue gas bypass evaporation and drying process or a low-temperature flue gas waste heat multi-effect flash evaporation concentration and reduction process + high-temperature flue gas bypass evaporation and drying process.

[0004] Patent (CN 117263300 A) discloses a process and system for treating desulfurization wastewater from thermal power plants using low-temperature flue gas evaporation. The system significantly improves the concentration ratio of the desulfurization wastewater through segmented heat exchange between thin and thick slurries. The washing layer uses low-concentration wastewater spraying, effectively reducing crystallization in this area. However, the multi-layered spraying device and collectors inside the low-temperature evaporation tower increase the overall height of the tower and the operating flue gas resistance, leading to higher investment and operating costs. Furthermore, because the evaporation zone uses thick slurry spraying, crystallization and scaling become more pronounced with increasing concentration ratios, further increasing the difficulty of operation and maintenance.

[0005] Patent (CN 217437801 U) discloses a wastewater circulation device for flue gas waste heat concentration. It avoids cavitation and current fluctuations in the pump caused by air bubbles in the concentrated slurry, thus preventing them from affecting wastewater treatment efficiency, by drawing slurry from the bottom of the slurry tank. It also eliminates the need for an agitator in the slurry tank, preventing slurry leakage in case of agitator seal problems. However, in this patented technology, the circulation pump inlet is connected to both the bottom of the concentration tower and the bottom of the slurry tank, switched by a valve. When slurry is transported through the connecting pipe between the bottom of the concentration tower and the circulation pump inlet, the risk of air bubbles being drawn into the circulation pump, causing cavitation and current disturbances, still exists. Furthermore, the connecting pipe at the circulation pump inlet, which is not actively used, risks blockage due to stagnant slurry flow. In addition, this patent only eliminates the agitator in the slurry tank without taking other effective measures to agitate the slurry, making it difficult to avoid sedimentation and scaling, thus increasing the difficulty of operation and maintenance. Utility Model Content

[0006] In view of the problems of complex structure, high energy consumption and difficult maintenance of existing desulfurization wastewater zero-emission flue gas waste heat concentration equipment, this utility model provides a desulfurization wastewater zero-emission flue gas waste heat concentration equipment with simple structure, stable system operation and simple maintenance.

[0007] The technical solution adopted in this utility model is: A waste heat concentration device for zero-emission flue gas from desulfurization wastewater is characterized by comprising a concentration unit, a wastewater circulation pump, and a wastewater clarifier. The concentration unit is divided into a wastewater flow zone, a spray zone, and a demisting zone from bottom to top. The wastewater circulation area is connected to the top of the spray area via a wastewater circulation pump; the other connection is to the wastewater clarifier. The spray zone is equipped with a spray pipe at the top and a flue gas inlet at the bottom; the demisting zone is equipped with a flue gas outlet at the top. The wastewater clarifier is connected to the wastewater flow area via a slurry transfer pump, and the slurry in the wastewater clarifier is pumped to the wastewater flow area via the slurry transfer pump.

[0008] Preferably, the wastewater flow zone adopts a cone-shaped design with a smooth inner wall, a circulating wastewater outlet at the bottom, and a wastewater inlet and a concentrated slurry inlet at the top.

[0009] Preferably, the wastewater clarifier is a sludge suspension sedimentation tank with a conical or flat bottom and a sludge scraper. The wastewater clarifier has a central inlet at the top, a clear water outlet at the top, and a concentrated slurry outlet at the bottom.

[0010] Preferably, the concentrated slurry in the wastewater clarifier flows out from the concentrated slurry outlet of the wastewater clarifier, and after passing through the concentrated slurry transfer pump, flows into the wastewater circulation area from the concentrated slurry inlet; the wastewater in the wastewater circulation area flows out from the circulating wastewater outlet, and after passing through the wastewater circulation pump, flows into the wastewater clarifier from the central inlet of the wastewater clarifier.

[0011] Preferably, a concentrated wastewater discharge regulating valve is provided between the wastewater circulation pump outlet and the central inlet of the wastewater clarifier.

[0012] Preferably, the outlet of the slurry delivery pump and the inlet of the slurry delivery pump are connected by a slurry circulation pipe, and the slurry circulation pipe is equipped with a slurry circulation pipe isolation valve.

[0013] Preferably, the slurry circulation pipe is provided with a slurry discharge pipe, and the slurry discharge pipe is provided with a slurry discharge pipe isolation valve.

[0014] Preferably, the top of the spray zone is provided with a spray layer inlet. Wastewater in the wastewater circulation zone flows out through the circulating wastewater outlet, and after passing through the wastewater circulation pump, it flows into the spray pipe at the top of the spray zone from the spray layer inlet and is sprayed out by the spray pipe to form fine mist droplets.

[0015] Preferably, the flue gas inlet is inclined downward along the air intake direction, with an angle of 10~20° with the horizontal.

[0016] Preferably, the wastewater circulation pump is a centrifugal slurry pump, and the thick slurry conveying pump is a centrifugal slurry pump or a single screw pump.

[0017] The beneficial effects of this invention are as follows: The elimination of the traditional wastewater storage area and stirring measures within the thickening device significantly reduces the height of the thickening device, thereby effectively reducing project costs; the wastewater undergoes full-flow, high-speed circulation within the wastewater flow area, achieving strong slurry agitation without the need for stirring measures. This simplifies equipment structure, reduces supporting facilities, and lowers the risk of sedimentation and scaling within the tower, effectively reducing investment and operation / maintenance costs; the slurry discharged from the thickening device is treated by a thickener clarifier, separating the thick slurry from the clear slurry. This improves the operational flexibility of the process equipment and significantly reduces the risk of sedimentation and scaling in the thick slurry transport pipeline, thereby enhancing the reliability of the process system. This invention has the following advantages: (1) The thickening device eliminates the traditional wastewater storage area and stirring measures at the bottom, reduces the overall height of the thickening device, reduces operating energy consumption, and thus reduces engineering cost and operating cost; (2) The wastewater circulation zone of the concentration unit adopts a smooth inner wall conical hopper type; the wastewater in the wastewater circulation zone is circulated at full flow through the wastewater circulation pump, and strong disturbance and flushing are achieved through the high-speed flow of the slurry itself, without the need for additional stirring and flushing measures; this measure simplifies the equipment structure and reduces the risk of sedimentation and scaling in the tower, effectively reducing investment costs and operation and maintenance costs.

[0018] (3) The wastewater clarifier treats the concentrated wastewater discharged from the concentration unit into concentrated slurry and clear water, and then performs separate treatment, which reduces the risk of deposit, scaling and blockage in the transportation and subsequent treatment of concentrated wastewater, reduces the treatment cost and operation and maintenance cost, and also improves the flexibility and reliability of the process equipment operation.

[0019] (4) The present invention has a simple structure, strong resistance to impact loads, flexible, stable and reliable operation, and is easy to manage and maintain. Attached Figure Description

[0020] Figure 1 In one specific embodiment of this utility model, the wastewater clarifier adopts a conical bottom type; Figure 2 In another specific embodiment of this utility model, the wastewater clarifier adopts a flat-bottomed type with a sludge scraper. Among them: A. Raw flue gas; B. Saturated wet flue gas; C. Wastewater; D. Clear water; E. Thick slurry; F. Concentrated wastewater; I. ​​Wastewater circulation area; II. Spray area; III. Demisting area; 1. Concentrator; 2. Wastewater circulation pump; 3. Wastewater clarifier; 4. Thick slurry transfer pump; 11. Flue gas inlet; 12. Flue gas outlet; 13. Circulating wastewater outlet; 14. Spray layer inlet; 15. Wastewater inlet; 16. Thick slurry inlet; 21. Wastewater circulation pump inlet; 22. Wastewater circulation pump outlet; 23. Wastewater circulation pipe; 24. Concentrated wastewater discharge pipe; 25. Concentrated wastewater discharge regulating valve; 31. Wastewater clarifier center inlet; 32. Wastewater clarifier clear water outlet; 33. Wastewater clarifier thick slurry outlet; 34. Sludge scraper; 41. Thick slurry transfer pump inlet; 42. Thick slurry transfer pump outlet; 43. Thick slurry circulation pipe; 44. Thick slurry discharge pipe; 45. Thick slurry circulation pipe isolation valve; 46. Thick slurry discharge pipe isolation valve. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1-2 As shown, this utility model discloses a waste heat concentration device for zero-emission flue gas from desulfurization wastewater, comprising a concentration device 1, a wastewater circulation pump 2, a wastewater clarifier 3, and a slurry transfer pump 4. The concentration device 1 is divided into a wastewater flow zone I, a spray zone II, and a demisting zone III from bottom to top. The concentration device 1 of this utility model eliminates the traditional wastewater storage area and stirring measures, which can significantly reduce the height of the concentration device and thus effectively reduce the project cost.

[0023] In this embodiment, the bottom of the wastewater flow zone I is divided into two paths after passing through the wastewater circulation pump 2. One path connects to the top of the spray zone II, and the other path connects to the wastewater clarifier 3. The wastewater in the wastewater flow zone I can be pumped to the spray zone II by the wastewater circulation pump 2. The top of the spray zone II is equipped with a spray pipe, and the bottom is equipped with a flue gas inlet 11. The raw flue gas A entering the spray zone II comes into contact with, mixes with, and exchanges heat with the wastewater droplets sprayed from the top of the spray zone II. The top of the demisting zone III is equipped with a flue gas outlet 12. After the raw flue gas A and the wastewater droplets come into contact with, mix with, and exchange heat in the spray zone II, some of the wastewater absorbs heat and vaporizes, turning into water vapor, which enters the demisting zone III along with the flue gas and is discharged from the flue gas outlet 12 at the top of the demisting zone III. The unvaporized wastewater droplets collide with each other to form large droplets, which then fall under gravity and collect at the bottom of the wastewater flow zone I. Wastewater clarifier 3 is connected to wastewater circulation zone I via slurry transfer pump 4. The circulating wastewater collected in wastewater circulation zone I, along with supplementary wastewater C and slurry E delivered by slurry transfer pump 4, is mixed and then transported again by wastewater circulation pump 2 to the spray layer. After atomization, it undergoes a heat exchange reaction with the raw flue gas A entering the thickening unit 1. Wastewater in wastewater circulation zone I undergoes full-flow, high-speed circulation, achieving strong slurry agitation without the need for stirring. This simplifies equipment structure, reduces auxiliary facilities, and lowers the risk of sedimentation and scaling within the tower, effectively reducing investment and operating costs. The slurry discharged from the thickening unit 1 is treated by slurry clarifier 3, separating the slurry and clear water. This improves the flexibility of process equipment operation and significantly reduces the risk of sedimentation and scaling in the slurry delivery pipeline, thereby enhancing the reliability of the process system.

[0024] In this embodiment, the wastewater flow zone I adopts a cone-shaped design with a smooth inner wall, a circulating wastewater outlet 13 at the bottom, and a wastewater inlet 15 and a slurry inlet 16 at the top; the top of the spray zone II is provided with a spray layer inlet 14. The wastewater in the wastewater flow zone I flows out through the circulating wastewater outlet 13, passes through the wastewater circulation pump 2, and then flows into the spray pipe at the top of the spray zone II from the spray layer inlet 14, where it is sprayed out to form fine droplets.

[0025] In this embodiment, the wastewater clarifier 3 is a sludge suspension sedimentation tank with a conical or flat bottom and a sludge scraper. The top of the wastewater clarifier 3 is provided with a central inlet 31, and the bottom is provided with a concentrated slurry outlet 33. The concentrated slurry in the wastewater clarifier 3 flows out from the concentrated slurry outlet 33, passes through the concentrated slurry conveying pump 4, and then flows into the wastewater circulation zone I from the concentrated slurry inlet 16. The wastewater in the wastewater circulation zone I flows out from the circulating wastewater outlet 13, passes through the wastewater circulation pump 2, and then flows into the wastewater clarifier 3 from the central inlet 31.

[0026] like Figure 1Wastewater clarifier 3 adopts a conical bottom type, which is mainly used for desulfurization wastewater with a suspended solids concentration of no more than 500 ppm after pretreatment. Since the concentrated wastewater entering the wastewater clarifier has a low concentration of suspended solids, low liquid viscosity, and good fluidity, it is not easy to generate deposits and scale. In this working condition, a cone-bottom type sludge suspension sedimentation tank with no power equipment and a simple structure can meet the process requirements and is easy to operate and maintain.

[0027] like Figure 2 Wastewater clarifier 3 adopts a flat-bottomed design with a sludge scraper. This type is mainly used for desulfurization wastewater with a suspended solids concentration of 5000ppm~30000ppm that has not undergone pretreatment. Because the concentrated wastewater entering the wastewater clarifier has a high concentration of suspended solids, high liquid viscosity, and poor fluidity, it is easy to generate deposits and scale. In this case, a sludge suspension sedimentation tank with a flat bottom and a sludge scraper is used to meet the process requirements.

[0028] In this embodiment, the outlet 42 of the slurry delivery pump 4 and the inlet 16 of the slurry delivery pump 4 are connected by a slurry circulation pipe 43, and a slurry circulation pipe isolation valve 45 is provided on the slurry circulation pipe 43; a slurry discharge pipe 44 is provided on the slurry circulation pipe 43, and a slurry discharge pipe isolation valve 46 is provided on the slurry discharge pipe 44. Combined with... Figure 1 When the equipment of this utility model is used to treat desulfurization wastewater with a suspended solids concentration of no more than 500 ppm, the slurry circulation pipe isolation valve 45 is in the normally open state. During operation, the slurry discharge pipe isolation valve 46 is opened briefly to discharge the slurry, thereby controlling the suspended solids concentration of the circulating wastewater in the thickening device to 2000 ppm ~ 8000 ppm and maintaining the stable operation of the device. Figure 2 When the equipment of this utility model is used to treat desulfurization wastewater with a suspended solids concentration of 5000ppm to 30000ppm, only a concentrated slurry discharge pipe 44 is provided at the outlet of the concentrated slurry conveying pump 4. During operation, concentrated slurry is continuously discharged through the concentrated slurry discharge pipe 44 to control the suspended solids concentration of the circulating wastewater in the thickening device to not exceed 80000ppm, so as to maintain the stable operation of the device.

[0029] In this embodiment, a concentrated wastewater discharge regulating valve 25 is provided between the wastewater circulation pump outlet 22 of the wastewater circulation pump 2 and the central inlet 31 of the wastewater clarifier. The opening of the concentrated wastewater discharge regulating valve 25 can be controlled according to actual needs to ensure that the concentration ratio of the wastewater in the concentration device 1 meets the design requirements. Specifically, a density measuring device can be installed on the inlet pipe of the wastewater circulation pump 2, and the opening of the concentrated wastewater discharge regulating valve 25 is interlocked with the measurement result of the density measuring device.

[0030] In this embodiment, the wastewater clarifier 3 is provided with a wastewater clarifier clear water outlet 32 ​​at the top.

[0031] In this embodiment, the flue gas inlet 11 is inclined downward along the air intake direction, with an angle of 10~20° with the horizontal.

[0032] In this embodiment, the wastewater circulation pump 2 is a centrifugal slurry pump, and the thick slurry conveying pump 4 is a centrifugal slurry pump or a single screw pump.

[0033] When the equipment of this utility model is in operation, the raw flue gas A enters the thickening device 1 from the flue gas inlet 11 located at the bottom of the spray zone II. The circulating wastewater is pressurized by the wastewater circulation pump 2 and sprayed out from the top of the spray zone II to form fine mist droplets. The two come into contact, mix and exchange heat in the spray zone II. Some of the wastewater absorbs heat and vaporizes into water vapor and enters the demisting zone III together with the flue gas. The unvaporized wastewater droplets collide with each other to form large droplets and fall down by gravity and collect in the wastewater circulation zone I. The saturated wet flue gas B formed by the mixture of flue gas and water vapor carries a large number of fine mist droplets due to the airflow. After being removed by the demister in the demisting zone III of the thickening device 1, it is discharged from the thickening device 1 through the flue gas outlet 12. The circulating wastewater collected in the wastewater circulation zone I is mixed with the supplemented wastewater C and the thick slurry E transported by the thick slurry transfer pump 4 and then transported to the spray layer by the wastewater circulation pump 2. After atomization, it exchanges heat with the raw flue gas A entering the thickening device 1.

[0034] The concentrated wastewater F, discharged through the wastewater circulation pump outlet 22 and the concentrated wastewater discharge pipe 24, enters the wastewater clarifier 3. Under the action of gravity, the suspended solids in the concentrated wastewater F collect at the bottom of the wastewater clarifier 3, are discharged from the slurry outlet 33, and are transported to the thickening device 1 for circulation treatment or discharged from the system for further disposal via the slurry transfer pump 4; the clarified water D is discharged through the clear water outlet 32 ​​for subsequent treatment.

[0035] The foregoing has shown and described the basic principles and main structural features of this utility model. This utility model is not limited to the above examples; various changes and modifications can be made without departing from the spirit and scope of this utility model, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A waste heat concentration device for zero-emission flue gas from desulfurization wastewater, characterized in that: It includes a thickening device (1), a wastewater circulation pump (2) and a wastewater clarifier (3). The thickening device (1) is divided into a wastewater flow zone (I), a spray zone (II) and a demisting zone (III) from bottom to top. Wastewater circulation zone (I) is connected to the top of spray zone (II) via wastewater circulation pump (2), and to wastewater clarifier (3) via another route; The spray zone (II) is equipped with a spray pipe at the top and a flue gas inlet (11) at the bottom; the demisting zone (III) is equipped with a flue gas outlet (12) at the top. The wastewater clarifier (3) is connected to the wastewater flow area (I) via the slurry transfer pump (4), and the slurry in the wastewater clarifier (3) is pumped to the wastewater flow area (I) via the slurry transfer pump (4).

2. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 1, characterized in that: The wastewater circulation area (I) adopts a cone-shaped design with a smooth inner wall, and is provided with a circulating wastewater outlet (13) at the bottom and a wastewater inlet (15) and a slurry inlet (16) at the top.

3. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 1, characterized in that: The wastewater clarifier (3) is a sludge suspension sedimentation tank with a cone bottom or flat bottom and a sludge scraper. The wastewater clarifier (3) has a central inlet (31) at the top, a clear water outlet (32) at the top, and a concentrated slurry outlet (33) at the bottom.

4. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 3, characterized in that: The slurry in the wastewater clarifier (3) flows out from the slurry outlet (33) of the wastewater clarifier, and after passing through the slurry transfer pump (4), it flows into the wastewater circulation area (I) from the slurry inlet (16); the wastewater in the wastewater circulation area (I) flows out from the circulating wastewater outlet (13), and after passing through the wastewater circulation pump (2), it flows into the wastewater clarifier (3) from the central inlet (31) of the wastewater clarifier.

5. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 3, characterized in that: A concentrated wastewater discharge regulating valve (25) is provided between the wastewater circulation pump outlet (22) of the wastewater circulation pump (2) and the central inlet (31) of the wastewater clarifier.

6. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 4, characterized in that: The slurry pump outlet (42) of the slurry pump (4) is connected to the slurry inlet (16) through a slurry circulation pipe (43), and a slurry circulation pipe isolation valve (45) is provided on the slurry circulation pipe (43).

7. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 6, characterized in that: The slurry circulation pipe (43) is provided with a slurry discharge pipe (44), and the slurry discharge pipe (44) is provided with a slurry discharge pipe isolation valve (46).

8. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 1, characterized in that: The top of the spray zone (II) is provided with a spray layer inlet (14). Wastewater in the wastewater flow zone (I) flows out through the circulating wastewater outlet (13), and after passing through the wastewater circulation pump (2), it flows into the spray pipe at the top of the spray zone (II) from the spray layer inlet (14) and is sprayed out by the spray pipe to form fine mist droplets.

9. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 1, characterized in that: The flue gas inlet (11) is inclined downward along the air intake direction, with an angle of 10~20° with the horizontal.

10. The waste heat concentration equipment for zero-emission flue gas from desulfurization wastewater according to claim 1, characterized in that: The wastewater circulation pump (2) is a centrifugal slurry pump, and the thick slurry conveying pump (4) is a centrifugal slurry pump or a single screw pump.

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