Gasification ash water quality optimization device and optimization method thereof

Abstract

The application belongs to the technical field of pressurized gasification device and water treatment, and particularly discloses a gasification ash water quality optimization device and an optimization method thereof. The device comprises a flash evaporation system and a sedimentation system. The flash evaporation system comprises a high-pressure flash tank, a saturated hot water tower, a high-flash condenser and a high-pressure flash separator which are sequentially connected in sequence. The sedimentation system comprises a plurality of sedimentation tanks, and the sedimentation tanks comprise a sedimentation tank body A for removing turbidity and a sedimentation tank body B for removing hardness. The high-pressure flash tank is used for treating black water from a gasification furnace and a washing tower. The high-pressure flash tank is connected with a low-pressure flash tank. The low-pressure flash tank is connected with an oxygen remover, an acid gas condenser and an acid gas separator. The acid gas separator is connected with the sedimentation tank. The gasification ash water quality optimization device and the optimization method thereof are reasonable in design, simple in structure, safe and reliable, convenient to use, and have good popularization and application value.

Description

Technical Field

[0001] This invention relates to the fields of pressurized gasification devices and water treatment technology, and in particular to a device and method for optimizing the quality of gasified ash water. Background Technology

[0002] In existing technologies, black water produced by gasification units typically undergoes three to four stages of flash evaporation treatment before entering a settling tank. The water in the settling tank then overflows into an ash water tank. The flash steam generated during flash evaporation is condensed and sent to a deaerator. The pH value of the gasification ash water is generally controlled at around 8. The ash water has high hardness, with a total hardness reaching approximately 1000 mg / L, and the majority of this hardness is calcium. High hardness leads to accelerated scaling in pipelines, requiring frequent high-pressure cleaning during single-furnace maintenance, which affects the long-term stable operation of the system. Conventional methods for water quality control involve adding flocculants and dispersants to adjust the ash water quality. However, this method cannot fundamentally remove scaling ions from the water. It requires increasing the replacement water volume and the amount of wastewater discharged to reduce system hardness, leading to increased subsequent water treatment costs and hindering water conservation.

[0003] In addition, the inlet pipeline from the sludge tank to the settling tank is located near the overflow weir of the settling tank. After the black water from the sludge tank enters the settling tank, the residence time is too short, and it basically enters the ash water tank directly, which leads to an increase in the turbidity of the ash water and affects the operation of the gasification system. Summary of the Invention

[0004] The purpose of this invention is to provide a gasification ash water quality optimization device and its optimization method, which is reasonably designed, simple in structure, safe and reliable, and easy to use, and has great value for promotion and application.

[0005] To achieve the above objectives, the present invention provides a gasification ash water quality optimization device, comprising a flash evaporation system and a settling system. The flash evaporation system comprises a high-pressure flash tank, a saturated hot water tower, a high-speed flash condenser, and a high-pressure flash separator connected in sequence by steam outlets. The settling system comprises a plurality of settling tanks, including a settling tank A for turbidity removal and a settling tank B for hardness removal. The high-pressure flash tank is used to treat black water from the gasifier and scrubbing tower. The liquid outlet of the high-pressure flash tank is connected to a low-pressure flash tank. The steam outlet of the low-pressure flash tank is connected to a deaerator, an acid gas condenser, and an acid gas separator. The liquid outlet of the acid gas separator is connected to the settling tank. The liquid outlet of the high-pressure flash separator is connected to the first vacuum flash tank. The liquid outlet of the low-pressure flash tank is connected to the first vacuum flash tank. The first vacuum flash tank is also used to treat black water from the slag pool pump. The steam outlet of the first vacuum flash tank is connected to the second vacuum flash tank via the first vacuum flash condenser and the first vacuum flash separator. The steam outlet of the second vacuum flash tank is connected to the settling tank via the second vacuum flash condenser, the second vacuum flash separator, and the vacuum flash condensate pump.

[0006] Preferably, the steam outlet of the high-pressure flash separator is connected to a stripping tower.

[0007] Preferably, the steam outlet of the second vacuum flash separator is connected to a vacuum ejector, and the vacuum ejector is connected to a vacuum pump via a jet condenser. The steam outlet of the first vacuum flash separator is connected to the vacuum pump.

[0008] Preferably, the bottom of the second vacuum flash tank is connected to the settling tank via a settling tank feed pump.

[0009] Preferably, it also includes a liquid alkali mixer and a flocculant mixer, both of which are installed on the pipeline from which the effluent of the flash evaporation system enters the settling tank.

[0010] Preferably, the settling tank is used to treat the black water from the sedimentation tank. The black water from the sedimentation tank is connected to the middle of the settling tank via a sedimentation tank pump. The sludge at the bottom of the settling tank is connected to the filter press system via a sedimentation tank underflow pump.

[0011] Preferably, the ash water overflowing from the settling tank is connected to an ash water tank body via a carbon dioxide mixer, the ash water tank body is connected to a gasification system via an ash water pump, a wastewater cooler is also provided between the ash water pump and the gasification system, and the wastewater cooler is connected to a sewage treatment device.

[0012] This invention also provides a method for optimizing the quality of gasified ash water, comprising the following steps: Most of the black water from the flash evaporation system enters the turbidity removal settling tank A. A certain proportion is controlled so that a small portion of the black water enters the hardness removal settling tank B. Liquid alkali and carbon dioxide are only added to the inlet and outlet of the hardness removal settling tank B. The amount of flocculant added is reasonably allocated according to the amount of black water treated by the two settling tanks and the quality of the effluent. Through the synergistic treatment of the two settling tanks, the ash water after hardness and turbidity removal is mixed in the ash water tank. After the flash evaporation system flashes out the acidic gas, the condensate from the second vacuum flash separator and the acidic gas separator is led to the hardening settling tank B. The amount of liquid alkali added and the amount of hardening black water are adjusted according to the hardness of the ash water coming out of the hardening settling tank B and the total hardness of the ash water mixed in the ash water tank. Based on the pH value of the effluent from the hardening settling tank B and the pH value of the mixed ash water in the ash water tank, adjust the amount of carbon dioxide gas introduced into the ash water to maintain the pH value of the gasification system within a reasonable range. The black water treated by the hardening settling tank B is relatively small in volume and has a relatively long retention time. The black water in the sludge tank is pumped into the middle of the hardening settling tank B after being pumped into the sludge tank. The sediment at the bottom of the two settling tanks is sent to the filter press system for treatment after being pumped into the bottom flow of the settling tank.

[0013] Therefore, the present invention employs the above-mentioned gasification ash water quality optimization device and optimization method, and the beneficial effects are as follows: (1) In this invention, water with high alkalinity in the slag water system is separately introduced into the settling tank. First, the alkalinity is replenished by the water system itself through optimization and adjustment. At the same time, an appropriate amount of liquid alkali is added to the inlet of the settling tank. After the pH value is appropriately increased, some of the calcium hardness in the ash water can be eliminated. After the total hardness of the entire gasification water system is reduced, the scaling speed of the system can be slowed down, the frequency of system maintenance can be reduced, the cost of pipeline cleaning can be reduced, and the stable operation time of the gasifier can be extended.

[0014] (2) By introducing the black water from the sedimentation tank into the central area of ​​the settling tank, the present invention can fully mix the black water from the sedimentation tank with the flocculant, increase the residence time of the black water from the sedimentation tank in the settling tank, which is beneficial to reduce the turbidity of the low-pressure ash water, improve the water quality of the system, and reduce the frequency of back-cutting of the inlet filter of the high-pressure ash water pump.

[0015] (3) After the hardening of the black water in the settling tank is completed, the carbon dioxide released from the low-temperature methanol wash is introduced into the ash water. On the one hand, it is used to adjust the pH value of the ash water, and on the other hand, it can replenish the alkalinity of the ash water. This effectively controls the alkalinity and hardness of the ash water within the normal range. As the hardness of the ash water decreases, the amount of dispersant added can be reduced accordingly, and the amount of wastewater discharged to the sewage treatment device can also be reduced, thereby reducing the operating cost of the subsequent water treatment device.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process structure of an embodiment of the gasification ash water quality optimization device and optimization method of the present invention.

[0018] Figure Labels 1. High-pressure flash tank; 2. Saturated hot water tower; 3. High-speed flash condenser; 4. High-pressure flash separator; 5. Acid gas condenser; 6. Acid gas separator; 7. Sedimentation tank pump; 8. Liquid alkali mixer; 9. Flocculant mixer; 10. Carbon dioxide mixer; 11. Settling tank underflow pump; 12. Ash water pump; 13. Wastewater cooler; 14. Jet condenser; 15. Vacuum ejector; 16. Vacuum pump; 17. 18. First vacuum flash separator; 19. First vacuum flash condenser; 20. Low-pressure flash tank; 21. First vacuum flash tank; 22. Second vacuum flash condenser; 23. Second vacuum flash separator; 24. Vacuum flash condensate pump; 25. Settling tank feed pump; 26. Second vacuum flash tank; 27. Sludge tank body; 28. Settling tank body A; 29. ​​Settling tank body B; 30. Ash water tank body; 31. Deaerator. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0021] Example 1 like Figure 1 As shown, a gasified ash water quality optimization device includes a flash evaporation system and a settling system. The flash evaporation system includes a high-pressure flash tank 1, a saturated hot water tower 2, a high-speed flash condenser 3, and a high-pressure flash separator 4, all connected in sequence by steam outlets. The settling system includes several settling tanks, including a settling tank A 27 for turbidity removal and a settling tank B 28 for hardness removal. It also includes a liquid alkali mixer 8 and a flocculant mixer 9, both of which are installed on the pipeline from the flash evaporation system into the settling tanks.

[0022] The high-pressure flash tank 1 is used to treat black water from the gasifier and the scrubbing tower. The liquid outlet of the high-pressure flash tank 1 is connected to the low-pressure flash tank 19. The steam outlet of the low-pressure flash tank 19 is connected to the deaerator 30, the acid gas condenser 5 and the acid gas separator 6. The liquid outlet of the acid gas separator 6 is connected to the settling tank.

[0023] The steam outlet of the high-pressure flash separator 4 is connected to a stripping tower. The liquid outlet of the high-pressure flash separator 4 is connected to the first vacuum flash tank 20. The liquid outlet of the low-pressure flash tank 19 is connected to the first vacuum flash tank 20. The first vacuum flash tank 20 is also used to treat the black water from the slag pool pump. The steam outlet of the first vacuum flash tank 20 is connected to the second vacuum flash tank 25 via the first vacuum flash condenser 18 and the first vacuum flash separator 17. The steam outlet of the second vacuum flash tank 25 is connected to the settling tank via the second vacuum flash condenser 21, the second vacuum flash separator 22, and the vacuum flash condensate pump 23.

[0024] The steam outlet of the second vacuum flash separator 22 is connected to a vacuum ejector 15, which is connected to a vacuum pump 16 via a jet condenser 14. The steam outlet of the first vacuum flash separator 17 is connected to the vacuum pump 16. The bottom of the second vacuum flash tank 25 is connected to the settling tank via a settling tank feed pump 24.

[0025] The settling tank is used to treat the black water from the sludge tank 26. The black water from the sludge tank 26 is connected to the middle of the settling tank via the sludge tank pump 7. The sludge at the bottom of the settling tank is connected to the filter press system via the bottom flow pump 11. The ash water overflowing from the settling tank is connected to the ash water tank 29 via the carbon dioxide mixer 10. The ash water tank 29 is connected to the gasification system via the ash water pump 12. A wastewater cooler 13 is also installed between the ash water pump 12 and the gasification system. The wastewater cooler 13 is connected to a sewage treatment device.

[0026] Specifically, the black water from the gasifier and the scrubbing tower enters the high-pressure flash tank 1. The steam from the high-pressure flash tank 1 enters the saturated hot water tower 2. The high-pressure flash steam is scrubbed with deoxygenated water in the saturated hot water tower 2, then cooled by the high-pressure flash condenser 3 before being sent to the high-pressure flash separator 4. The steam from the high-pressure flash separator 4 is sent to the steam stripping tower, and the high-pressure flash condensate is sent to the first vacuum flash tank 20. The liquid from the high-pressure flash tank 1 enters the low-pressure flash tank 19. The steam from the low-pressure flash tank 19 is sent to the deaerator 30. The steam from the deaerator 30 is then... After passing through acid gas condenser 5, the liquid is sent to acid gas separator 6. The liquid outlet of acid gas separator 6 is sent to settling tank. The black water from the slag pool pump is also sent to the first vacuum flash tank 20. The steam outlet of the first vacuum flash tank 20 passes through the first vacuum flash condenser 18 and is sent to the first vacuum flash separator 17. The liquid outlet of the first vacuum flash tank 20 enters the second vacuum flash tank 25. The steam outlet of the second vacuum flash tank 25 passes through the second vacuum flash condenser 21 and is then condensed with the liquid from the first vacuum flash separator 17. The liquid is fed into the second vacuum flash separator 22. The steam outlet of the second vacuum flash separator 22 is connected to the vacuum ejector 15. The ejected steam passes through the ejector condenser 14 and enters the vacuum pump 16 together with the steam outlet of the first vacuum flash separator 17. The liquid outlet of the second vacuum flash separator 22 is sent to the settling tank through the vacuum flash condensate pump 23. The black water discharged from the bottom of the second vacuum flash tank 25 is sent to the settling tank through the settling tank feed pump 24. The black water and condensate are then mixed and sent to the liquid alkali mixing tank. After passing through flocculant mixer 9, the sludge is sent to the middle of the settling tank. The black water in the sludge tank 26 is also sent to the middle of the settling tank through sludge tank pump 7. The sludge at the bottom of the settling tank is sent to the filter press system for treatment through the bottom flow pump 11. The ash water overflowing from the settling tank enters the ash water tank 29 after passing through carbon dioxide mixer 10. The ash water in the ash water tank 29 is sent to the sewage treatment plant through ash water pump 12, and most of it is sent to the gasification system for recycling.

[0027] A method for optimizing the quality of gasified ash water, comprising the following steps: Two settling tanks are used. One tank, A27, is mainly used for turbidity removal. Most of the black water from the flash evaporation system enters the turbidity removal settling tank A27. The other tank, B28, is mainly used for hardening removal. A certain proportion of the black water is controlled so that a small portion of the black water enters the hardening removal settling tank B28. Liquid alkali and carbon dioxide are only added to the inlet and outlet of the hardening removal settling tank B28. The amount of flocculant added is reasonably distributed according to the amount of black water treated by the two settling tanks and the quality of the effluent. Through the synergistic treatment of the two settling tanks, the ash water after hardening and turbidity removal is finally mixed in the ash water tank 29, thereby achieving the overall hardening removal purpose of the gasification water system.

[0028] After the flash evaporation system of the slag water releases acidic gases, the pH value of the water will increase, which will help increase the alkalinity. The condensate from the second vacuum flash separator 22 and the acid gas separator 6 is led to the hardening settling tank B 28 to enhance the hardening removal effect. Based on the hardness of the ash water coming out of the hardening settling tank B 28 and the total hardness of the ash water mixed in the ash water tank 29, the amount of liquid alkali added and the amount of black water removed are adjusted to minimize the amount of liquid alkali added, thereby reducing the introduction of sodium ions and reducing the load on the downstream salt separation treatment device.

[0029] Based on the pH value of the effluent from the hardening settling tank B 28 and the pH value of the mixed ash water in the ash water tank 29, adjust the amount of carbon dioxide gas introduced into the ash water to maintain the pH value of the gasification system within a reasonable range.

[0030] The black water treated by the hardening settling tank B 28 is relatively small and has a relatively long retention time. The black water in the sludge tank 26 is sent to the middle of the hardening settling tank B 28 after being pumped by the sludge tank pump 7. This is more conducive to the settling of black water. The sediment at the bottom of the two settling tanks is sent to the filter press system for treatment after being pumped by the bottom flow pump 11.

[0031] Therefore, the gasification ash water quality optimization device and optimization method described above are reasonably designed, simple in structure, safe and reliable, and easy to use, and have great value for promotion and application.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A device for optimizing the quality of gasified ash water, characterized in that: It includes a flash evaporation system and a settling system. The flash evaporation system includes a high-pressure flash tank, a saturated hot water tower, a high-speed flash condenser, and a high-pressure flash separator, which are connected in sequence by steam outlets. The settling system includes several settling tanks, including a settling tank A for turbidity removal and a settling tank B for hardness removal. The high-pressure flash tank is used to treat black water from the gasifier and scrubbing tower. The liquid outlet of the high-pressure flash tank is connected to a low-pressure flash tank. The steam outlet of the low-pressure flash tank is connected to a deaerator, an acid gas condenser, and an acid gas separator. The liquid outlet of the acid gas separator is connected to the settling tank. The liquid outlet of the high-pressure flash separator is connected to the first vacuum flash tank. The liquid outlet of the low-pressure flash tank is connected to the first vacuum flash tank. The first vacuum flash tank is also used to treat black water from the slag pool pump. The steam outlet of the first vacuum flash tank is connected to the second vacuum flash tank via the first vacuum flash condenser and the first vacuum flash separator. The steam outlet of the second vacuum flash tank is connected to the settling tank via the second vacuum flash condenser, the second vacuum flash separator, and the vacuum flash condensate pump. The method for optimizing the quality of gasified ash water using the aforementioned gasified ash water optimization device includes the following steps: Most of the black water from the flash evaporation system enters the turbidity removal settling tank A. A certain proportion is controlled so that a small portion of the black water enters the hardness removal settling tank B. Liquid alkali and carbon dioxide are only added to the inlet and outlet of the hardness removal settling tank B. The amount of flocculant added is reasonably allocated according to the amount of black water treated by the two settling tanks and the quality of the effluent. Through the synergistic treatment of the two settling tanks, the ash water after hardness and turbidity removal is mixed in the ash water tank. After the flash evaporation system flashes out the acidic gas, the condensate from the second vacuum flash separator and the acidic gas separator is led to the hardening settling tank B. The amount of liquid alkali added and the amount of hardening black water are adjusted according to the hardness of the ash water coming out of the hardening settling tank B and the total hardness of the ash water mixed in the ash water tank. Based on the pH value of the effluent from the hardening settling tank B and the pH value of the mixed ash water in the ash water tank, adjust the amount of carbon dioxide gas introduced into the ash water to maintain the pH value of the gasification system within a reasonable range. The black water treated by the hardening settling tank B is relatively small in volume and has a relatively long retention time. The black water in the sludge tank is pumped into the middle of the hardening settling tank B after being pumped into the sludge tank. The sediment at the bottom of the two settling tanks is sent to the filter press system for treatment after being pumped into the bottom flow of the settling tank.

2. The gasification ash water quality optimization device according to claim 1, characterized in that: The steam outlet of the high-pressure flash separator is connected to a stripping tower.

3. The gasification ash water quality optimization device according to claim 1, characterized in that: The steam outlet of the second vacuum flash separator is connected to a vacuum ejector, which is connected to a vacuum pump via a jet condenser. The steam outlet of the first vacuum flash separator is connected to the vacuum pump.

4. The gasification ash water quality optimization device according to claim 1, characterized in that: The bottom of the second vacuum flash tank is connected to the settling tank via a settling tank feed pump.

5. The gasification ash water quality optimization device according to claim 1, characterized in that: It also includes a liquid alkali mixer and a flocculant mixer, both of which are installed on the pipeline from the effluent of the flash evaporation system into the settling tank.

6. The gasification ash water quality optimization device according to claim 1, characterized in that: The settling tank is used to treat the black water from the sedimentation tank. The black water from the sedimentation tank is connected to the middle of the settling tank via a sedimentation tank pump. The sludge at the bottom of the settling tank is connected to the filter press system via a sedimentation tank underflow pump.

7. The gasification ash water quality optimization device according to claim 1, characterized in that: The ash water overflowing from the settling tank is connected to the ash water tank body via a carbon dioxide mixer. The ash water tank body is connected to a gasification system via an ash water pump. A wastewater cooler is also installed between the ash water pump and the gasification system. The wastewater cooler is connected to a sewage treatment device.

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