A slag water treatment device for a pressurized gasification device and a back-cutting method thereof

Abstract

The present invention discloses a slag water treatment device for a pressurized gasification device and a reverse cutting method thereof, and belongs to the technical field of coal gasification devices. The slag water treatment device for a pressurized gasification device comprises a plurality of parallel processing units, wherein the processing units comprise a high-pressure flash tank, the high-flash gas outlet of the high-pressure flash tank is connected to the ash water heater through a first air inlet pipe, the air outlet of the ash water heater is connected to the air inlet of the high-flash cooler through a first outlet pipe, the high-flash gas outlet of the high-pressure flash tank is connected to the saturated hot water tower through a second air inlet pipe, the deaerator is connected to the saturated hot water tower through a water adding structure, the liquid outlet of the saturated hot water tower is connected to the first inlet pipe through a third outlet pipe via a first water outlet main pipe; the deoxygenated water main pipe is connected to both the first inlet pipe and the second inlet pipe, and the first return pipe and the second return pipe are connected to the deaerator. The use of the slag water treatment device for a pressurized gasification device and the reverse cutting method thereof described in the present invention can solve the problem of small flash gas condensation amount in the existing device.

Description

Technical Field

[0001] The invention relates to the technical field of coal gasification devices, and in particular to a slag water treatment device of a pressurized gasification device and a back-cutting method thereof. Background Art

[0002] Coal gasification black water is wastewater produced during the coal gasification process that contains a large amount of suspended solids, high-concentration organic matter, ammonia nitrogen, phenols and other pollutants. Its formation mainly stems from the fact that when coal is gasified, minerals, additives and incompletely reacted hydrocarbons in the coal are taken out with high-temperature steam and formed into wastewater after cooling. Black water is highly polluting and direct discharge will cause serious harm to the environment, so it is necessary to treat black water. The black water left after flash evaporation through the high-pressure flash tank generally adopts the gray water heater process. This process is set up in which the gray water delivered by the high-pressure gray water pump and the high flash gas from the high-pressure flash tank are heat exchanged in a partitioning manner. Because the water quality of the gray water is not very good, there are many suspended solids and high hardness in the gray water, which is easy to clog and scale. In addition, the high flash gas is also relatively dirty. Affected by these factors, the gray water heater is used for a short time, and the heat exchange effect will be greatly reduced, resulting in a gradual decrease in the condensation amount of high-pressure flash steam and an increase in the amount of high flash gas. The conversion stripping tower cannot digest such a large amount of gas, so it can only be vented for treatment, resulting in a great waste. At the same time, the temperature of the high-pressure ash water cannot be raised, which affects the water-gas ratio of the synthesis gas at the outlet of the scrubbing tower. In addition, the ash water heater is prone to leakage and often requires maintenance, which has a relatively large impact on the production system. Summary of the invention

[0003] The object of the present invention is to provide a slag water treatment device for a pressurized gasification device and a back-cutting method thereof, so as to solve the problem of small flash gas condensation amount in the existing device.

[0004] To achieve the above-mentioned purpose, the present invention provides a slag water treatment device of a pressurized gasification device, comprising a plurality of parallel treatment units, wherein the treatment units include a high-pressure flash tank, an ash water heater, a saturated hot water tower, a deaerator, a high-pressure ash water pump and a high-flash cooler, the high-flash gas outlet of the high-pressure flash tank is connected to the ash water heater through a first air inlet pipe, the air outlet of the ash water heater is connected to the air inlet of the high-flash cooler through a first outlet pipe, the high-flash gas outlet of the high-pressure flash tank is connected to the saturated hot water tower through a second air inlet pipe, the deaerator is connected to the saturated hot water tower through a water adding structure, the liquid outlet of the saturated hot water tower is connected to the first inlet pipe of the high-pressure ash water pump through a third outlet pipe via a first water outlet main pipe; the first water outlet pipe of the deaerator is connected to the first inlet pipe of the high-pressure ash water pump and the second inlet pipe of the deaerator through the deaerator water main pipe, the first reflux pipe of the high-pressure ash water pump is connected to the deaerator, and the second reflux pipe of the deaerator is connected to the deaerator.

[0005] Preferably, the air outlet of the saturated hot water tower is connected to the first outlet pipe through a first air outlet pipe, and valves are provided on the first air outlet pipe and the first outlet pipe.

[0006] Preferably, the first air inlet pipe and the second air inlet pipe are both provided with valves, the first inlet pipe and the second inlet pipe are both provided with valves, and the first return pipe and the second return pipe are both provided with valves.

[0007] Preferably, the water adding structure includes an upper water adding component and a lower water adding component, the upper water adding component includes an upper water adding pipe, the upper water adding pipe is connected to the second water outlet pipe of the deoxygenation pump through the second water outlet main pipe, the second water outlet pipe is provided with a valve, and the upper water adding pipe is provided with a valve and a flow regulating valve.

[0008] Preferably, the lower water adding assembly comprises a lower water adding pipe, which is connected to the second water outlet pipe of the deaerator pump through the second water outlet main pipe, and a valve and a liquid level regulating valve are arranged on the lower water adding pipe.

[0009] Preferably, the third outlet pipe is provided with a check valve and an outlet valve.

[0010] Preferably, a limiting flow orifice plate is provided on the first reflux pipe.

[0011] Preferably, the second outlet pipe of the high-pressure grey water pump is connected to the grey water heater, and a valve is provided on the second outlet pipe.

[0012] Preferably, three processing units are provided.

[0013] The back-cutting method of the slag water treatment device based on the above-mentioned pressurized gasification device comprises the following steps:

[0014] S1, water cut: the water inlet of the high-pressure ash water pump is the deoxygenated water of the deaerator. The water of the deaerator is led to the deoxygenation pump through the first outlet pipe and the second inlet pipe. The deoxygenation pump is turned on to establish the liquid level of the saturated hot water tower; the first inlet pipe valve of the standby high-pressure ash water pump deoxygenated water inlet is closed, the ash water inlet valve on the first outlet main pipe is opened, and the outlet water of the saturated hot water tower is led to the inlet of the standby high-pressure ash water pump through the third outlet pipe and the first outlet main pipe. The standby high-pressure ash water pump is turned on. At this time, the three high-pressure ash water pumps are normally delivering gasification system at the same time;

[0015] S2, gas cutting: open the saturated hot water tower inlet valve on the second inlet pipe and the saturated hot water tower outlet valve on the first outlet pipe, send the high flash gas into the saturated hot water tower, close the inlet valve of the ash water heater on the first inlet pipe and the ash water heater outlet valve on the first outlet pipe, and cut the ash water heater gas phase out of the gasification system;

[0016] S3, the second saturated hot water tower is put into use: after the first saturated hot water tower is put into use normally, one high-pressure ash water pump is stopped. At this time, one high-pressure ash water pump uses the deoxygenated water of the deaerator, and one high-pressure ash water pump uses the ash water of the saturated hot water tower; repeat S1-S2, and switch the stopped high-pressure ash water pump to the ash water of the saturated hot water tower. At this time, two high-pressure ash water pumps use the ash water of the saturated hot water tower, and one high-pressure ash water pump uses the deoxygenated water of the deaerator. Stop the high-pressure ash water pump that uses the deoxygenated water, and complete the switch from the ash water heater process to the saturated hot water tower process;

[0017] S4. After the reverse cutting is completed, the standby high-pressure ash water pump keeps the deoxygenated water inlet valve of the high-pressure ash water pump on the first inlet pipe open, and the ash water inlet valve of the high-pressure ash water pump on the first outlet main pipe is closed, so that the standby high-pressure ash water pump uses deoxygenated water. The standby high-pressure ash water pump uses deoxygenated water to ensure normal water supply, which is beneficial to the stability of the gasification system.

[0018] The advantages and positive effects of the slag water treatment device of a pressurized gasification device and the back-cutting method thereof described in the present invention are:

[0019] 1. The present invention adds a saturated hot water tower. The deoxygenated water sent into the saturated hot water tower by the deoxygenation pump can directly contact the high flash gas for heat exchange and washing, thereby replacing the gray water heater, reducing the load of the gray water heater, improving the heat exchange effect, and facilitating the condensation amount of the high flash gas.

[0020] 2. The third outlet pipe of the saturated hot water tower is equipped with a check valve and an outlet valve. When the gasifier is turned over, there is a pressure difference between the saturated hot water towers. The check valve can prevent the water in the outlet main pipe of the saturated hot water tower from flowing back to the saturated hot water tower, ensuring the normal flow of the high-pressure ash water pump.

[0021] 3. The flow limiting orifice plate allows the reflux of the high-pressure ash water pump to continue to return to the deaerator instead of the saturated hot water tower, ensuring that after the ash water temperature of the high-pressure ash water pump is increased, the first return pipe will not cause pipeline vibration due to large amounts of gasification. In this way, the normal reflux of the high-pressure ash water pump will not be affected by the operation of the saturated hot water tower.

[0022] 4. The high-pressure ash water pump and deaerator pump in the two treatment units are in the normal mode, and the high-pressure ash water pump and deaerator pump in one treatment unit are in the standby mode. The standby high-pressure ash water pump is used to maintain the water inlet flow of the deaerator, and the high-pressure ash water pump is operated to maintain the water inlet flow of the saturated hot water tower, which can effectively prevent the deaerator pump from abnormal operation; when the liquid level of the saturated hot water tower is difficult to maintain, the high-pressure ash water pump can keep the total amount of ash water unchanged through the deaerator water inlet, thereby reducing the impact on the gasification system.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a structural schematic diagram of an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the installation structure of a gray water heater according to an embodiment of the present invention;

[0026] Figure 3 For attachment Figure 1 Middle A enlarged view;

[0027] Figure 4 For attachment Figure 1 Middle B is an enlarged view.

[0028] Reference numerals

[0029] 1. High-pressure flash tank; 2. Ash water heater; 3. Saturated hot water tower; 4. Deaerator; 5. Deaerator pump; 6. High-pressure ash water pump; 7. High-pressure flash cooler; 8. First air inlet pipe; 9. Second air inlet pipe; 10. First outlet pipe; 11. First air outlet pipe; 12. First water outlet pipe; 13. Deaerated water main pipe; 14. First inlet pipe; 15. Second inlet pipe; 16. First return pipe; 17. Limiting orifice; 18. Second return pipe; 19. Second outlet pipe; 20. Third outlet pipe; 21. Check valve; 22. Outlet valve; 23. First water outlet main pipe; 24. Upper water supply pipe; 25. Flow regulating valve; 26. Lower water supply pipe; 27. Liquid level regulating valve; 28. Second water outlet pipe; 29. ​​Second water outlet main pipe. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0031] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] Example

[0033] like Figure 1 , Figure 2 , Figure 3 , Figure 4As shown. A slag water treatment device of a pressurized gasification device includes a plurality of parallel processing units. In this embodiment, three processing units are provided. The processing unit includes a high-pressure flash tank 1, an ash water heater 2, a saturated hot water tower 3, a deoxygenation pump 5, a high-pressure ash water pump 6 and a high-flash cooler 7. The high-flash gas outlet of the high-pressure flash tank 1 is connected to the ash water heater 2 through a first air inlet pipe 8. The air outlet of the ash water heater 2 is connected to the air inlet of the high-flash cooler 7 through a first outlet pipe 10. The high-flash gas outlet of the high-pressure flash tank 1 is connected to the saturated hot water tower 3 through a second air inlet pipe 9. The air outlet of the saturated hot water tower 3 is connected to the first outlet pipe 10 through a first air outlet pipe 11, and valves are provided on the first air outlet pipe 11 and the first outlet pipe 10.

[0034] The deaerator 4 is connected to the saturated hot water tower 3 through a water adding structure. The water adding structure includes an upper water adding component and a lower water adding component. The upper water adding component includes an upper water adding pipe 24, which is connected to the second water outlet pipe 28 of the deaerator pump 5 through a second water outlet main pipe 29. A valve is provided on the second water outlet pipe 28, and a valve and a flow regulating valve 25 are provided on the upper water adding pipe 24. When the gasification system operates normally, the flow regulating valve 25 fixes a flow value to maintain the stability of the gas-liquid two-phase of the saturated hot water tower 3. The lower water adding component includes a lower water adding pipe 26, which is connected to the second water outlet pipe 28 of the deaerator pump 5 through a second water outlet main pipe 29. A valve and a liquid level regulating valve 27 are provided on the lower water adding pipe 26. The liquid level regulating valve 27 is used to control and adjust the liquid level of the saturated hot water tower 3. The deaerator 4 feeds deoxygenated water into the saturated hot water tower 3 through the upper water adding pipe 24 and the lower water adding pipe 26. Under normal circumstances, the amount of water entering the saturated hot water tower 3 is mainly water added, which can better cool and wash the high flash gas and increase the temperature of the gray water.

[0035] By adding a saturated hot water tower 3, the deoxygenated water sent into the saturated hot water tower 3 by the deoxygenation pump 5 can directly contact with the high flash gas for heat exchange and washing, replacing the gray water heater 2, reducing the load of the gray water heater 2, improving the heat exchange effect, and helping to increase the condensation amount of the high flash gas.

[0036] The liquid outlet of the saturated hot water tower 3 is connected to the first inlet pipe 14 of the high-pressure ash water pump 6 through the third outlet pipe 20 and the first outlet main pipe 23. The third outlet pipe 20 is provided with a check valve 21 and an outlet valve 22. When the gasifier is turned down, there is a pressure difference between the saturated hot water towers 3. The check valve 21 can prevent the water in the outlet main pipe of the saturated hot water tower 3 from flowing back to the saturated hot water tower 3, thereby ensuring the normal flow of the high-pressure ash water pump 6.

[0037] The first outlet pipe 12 of the deaerator 4 is connected to the first inlet pipe 14 of the high-pressure ash water pump 6 and the second inlet pipe 15 of the deaerator 5 through the deaerator water main pipe 13. The first return pipe 16 of the high-pressure ash water pump 6 is connected to the deaerator 4, and the second return pipe 18 of the deaerator 5 is connected to the deaerator 4. The second outlet pipe 19 of the high-pressure ash water pump 6 is connected to the ash water heater 2, and a valve is arranged on the second outlet pipe 19. A limiting flow orifice 17 is arranged on the first return pipe 16. The limiting flow orifice 17 allows the reflux of the high-pressure ash water pump 6 to continue to return to the deaerator 4, and does not return to the saturated hot water tower 3, ensuring that after the ash water temperature of the high-pressure ash water pump 6 is increased, the first return pipe 16 will not cause pipeline vibration due to a large amount of gasification, so that the normal reflux of the high-pressure ash water pump 6 is not affected by the operation of the saturated hot water tower 3.

[0038] The first air inlet pipe 8 and the second air inlet pipe 9 are both provided with valves, the first inlet pipe 14 and the second inlet pipe 15 are both provided with valves, and the first return pipe 16 and the second return pipe 18 are both provided with valves.

[0039] Among the three treatment units in the present embodiment, the high-pressure ash water pump 6 and the deaerator pump 5 in two treatment units are in the normal mode, and the high-pressure ash water pump 6 and the deaerator pump 5 in one treatment unit are in the standby mode. The standby high-pressure ash water pump 6 is used to maintain the water inlet flow of the deaerator 4, and the high-pressure ash water pump 6 is operated to maintain the water inlet flow of the saturated hot water tower 3, which can effectively prevent the deaerator pump 5 from abnormal operation; when the liquid level of the saturated hot water tower 3 is difficult to maintain, the high-pressure ash water pump 6 can keep the total amount of ash water unchanged through the deaerator 4 to reduce the impact on the gasification system.

[0040] When in use, the vaporized black water enters the high-pressure flash tank 1 for flash evaporation, and the outlet high-flash gas is divided into two paths. One path enters the gray water heater 2 through the first air inlet pipe 8, and enters the high-flash cooler 7 for cooling after being heated by the gray water heater 2 through the first outlet pipe 10. The other path enters the saturated hot water tower 3 through the second air inlet pipe 9. The deoxygenated water in the deaerator 4 enters the saturated hot water tower 3 through the deoxygenation pump 5 through the upper water pipe 24 and the lower water pipe 26. The deoxygenated water and the high-flash gas are in contact with each other in the saturated hot water tower 3 for heat exchange and washing. The washed high-flash gas enters the first outlet pipe 10 through the first air outlet pipe 11, and then is cooled by the high-flash cooler 7. The black water at the bottom of the high-pressure flash tank 1 is further flashed by low-flash.

[0041] The liquid in the saturated hot water tower 3 enters the first inlet pipe 14 of the high-pressure gray water pump 6 through the third outlet pipe 20 and the first outlet main pipe 23, and is then sent to the gray water heater 2 through the second outlet pipe 19 for heat exchange and cooling, and is discharged or processed in the next process.

[0042] The deoxygenated water in the deaerator 4 enters the high-pressure gray water pump 6 through the first water outlet pipe 12 and the deoxygenated water main pipe 13 via the first inlet pipe 14 , and then returns to the deaerator 4 via the first return pipe 16 and the flow limiting orifice plate 17 .

[0043] The deoxygenated water in the deaerator 4 enters the deoxygenation pump 5 through the first water outlet pipe 12 and the deoxygenated water main pipe 13 via the second inlet pipe 15 , and then returns to the deaerator 4 via the second reflux pipe 18 .

[0044] The back-cutting method of the slag water treatment device based on the above-mentioned pressurized gasification device comprises the following steps:

[0045] S1. Cut off water: the water inlet of the high-pressure ash water pump 6 is the deoxygenated water of the deaerator 4. The water of the deaerator 4 is introduced to the deoxygenation pump 5 through the first outlet pipe 12 and the second inlet pipe 15. The deoxygenation pump 5 is turned on to establish the liquid level of the saturated hot water tower 3. The valve of the first inlet pipe 14 of the deoxygenated water inlet of the standby high-pressure ash water pump 6 is closed, and the ash water inlet valve on the first outlet main pipe 23 is opened. The outlet water of the saturated hot water tower 3 is introduced into the inlet of the standby high-pressure ash water pump 6 through the third outlet pipe 20 and the first outlet main pipe 23. The standby high-pressure ash water pump 6 is turned on. At this time, the three high-pressure ash water pumps 6 are normally delivering gasification system at the same time.

[0046] S2, gas cutting: open the air inlet valve of the saturated hot water tower 3 on the second air inlet pipe 9 and the air outlet valve of the saturated hot water tower 3 on the first air outlet pipe 11, send the high flash gas into the saturated hot water tower 3, close the air inlet valve of the gray water heater 2 on the first air inlet pipe 8 and the outlet valve 22 of the gray water heater 2 on the first outlet pipe 10, and cut the gas phase of the gray water heater 2 out of the gasification system.

[0047] S3, the second saturated hot water tower 3 is put into use: after the first saturated hot water tower 3 is put into use normally, one high-pressure ash water pump 6 is stopped. At this time, one high-pressure ash water pump 6 uses the deoxygenated water of the deaerator 4, and one high-pressure ash water pump 6 uses the ash water of the saturated hot water tower 3; repeat S1-S2, and cut the stopped high-pressure ash water pump 6 to use the ash water of the saturated hot water tower 3. At this time, two high-pressure ash water pumps 6 use the ash water of the saturated hot water tower 3, and one high-pressure ash water pump 6 uses the deoxygenated water of the deaerator 4. The high-pressure ash water pump 6 using deoxygenated water is stopped, and the ash water heater 2 process is switched to the saturated hot water tower 3 process.

[0048] S4. After the reverse cutting is completed, the standby high-pressure ash water pump 6 keeps the deoxygenated water inlet valve of the high-pressure ash water pump 6 on the first inlet pipe 14 open, and the ash water inlet valve of the high-pressure ash water pump 6 on the first outlet main pipe 23 is closed, so that the standby high-pressure ash water pump 6 uses deoxygenated water. The standby ash water pump 6 uses deoxygenated water to ensure normal water supply, which is beneficial to the stability of the gasification system.

[0049] Therefore, the slag water treatment device of the pressurized gasification device and the back-cutting method thereof described in the present invention can solve the problem of small flash gas condensation amount in the existing device.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A back-cutting method for a slag water treatment device of a pressurized gasification device, characterized in that: The slag water treatment device of the pressurized gasification device includes a deaerator and three parallel processing units, the processing units include a high-pressure flash tank, an ash water heater, a saturated hot water tower, a deaerator pump, a high-pressure ash water pump and a high-flash cooler, the high-flash gas outlet of the high-pressure flash tank is connected to the ash water heater through a first air inlet pipe, the air outlet of the ash water heater is connected to the air inlet of the high-flash cooler through a first outlet pipe, the high-flash gas outlet of the high-pressure flash tank is connected to the saturated hot water tower through a second air inlet pipe, the deaerator is connected to the saturated hot water tower through a deaerator pump and a water adding structure, the liquid outlet of the saturated hot water tower is connected to the first inlet pipe of the high-pressure ash water pump through a third outlet pipe via a first water outlet main pipe; the first water outlet pipe of the deaerator is connected to the first inlet pipe of the high-pressure ash water pump and the second inlet pipe of the deaerator through the deaerator water main pipe, the first reflux pipe of the high-pressure ash water pump is connected to the deaerator, and the second reflux pipe of the deaerator is connected to the deaerator; The high-pressure ash water pump and deaerator pump in two treatment units are in the normal mode, and the high-pressure ash water pump and deaerator pump in one treatment unit are in the standby mode; The gas outlet of the saturated hot water tower is connected to the first outlet pipe through the first gas outlet pipe, and the first gas outlet pipe and the first outlet pipe are both provided with valves; the first gas inlet pipe and the second gas inlet pipe are both provided with valves, and the first inlet pipe and the second inlet pipe are both provided with valves; The following steps are involved: S1, water cut: the water inlet of the high-pressure ash water pump is the deoxygenated water of the deaerator. The water of the deaerator is led to the deoxygenation pump through the first outlet pipe and the second inlet pipe. The deoxygenation pump is turned on to establish the liquid level of the saturated hot water tower; the first inlet pipe valve of the standby high-pressure ash water pump deoxygenated water inlet is closed, the ash water inlet valve on the first outlet main pipe is opened, and the outlet water of the saturated hot water tower is led to the inlet of the standby high-pressure ash water pump through the third outlet pipe and the first outlet main pipe. The standby high-pressure ash water pump is turned on. At this time, the three high-pressure ash water pumps are normally delivering gasification system at the same time; S2, gas cutting: open the saturated hot water tower inlet valve on the second inlet pipe and the saturated hot water tower outlet valve on the first outlet pipe, send the high flash gas into the saturated hot water tower, close the inlet valve of the ash water heater on the first inlet pipe and the ash water heater outlet valve on the first outlet pipe, and cut the ash water heater gas phase out of the gasification system; S3, the second saturated hot water tower is put into use: after the first saturated hot water tower is put into use normally, one high-pressure ash water pump is stopped. At this time, one high-pressure ash water pump uses the deoxygenated water of the deaerator, and one high-pressure ash water pump uses the ash water of the saturated hot water tower; repeat S1-S2, and switch the stopped high-pressure ash water pump to the ash water of the saturated hot water tower. At this time, two high-pressure ash water pumps use the ash water of the saturated hot water tower, and one high-pressure ash water pump uses the deoxygenated water of the deaerator. Stop the high-pressure ash water pump that uses the deoxygenated water, and complete the switch from the ash water heater process to the saturated hot water tower process; S4. After the reverse cutting is completed, the standby high-pressure ash water pump keeps the deoxygenated water inlet valve of the high-pressure ash water pump on the first inlet pipe open, and the ash water inlet valve of the high-pressure ash water pump on the first outlet main pipe is closed, so that the standby high-pressure ash water pump uses deoxygenated water. The standby high-pressure ash water pump uses deoxygenated water to ensure normal water supply, which is beneficial to the stability of the gasification system.

2. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 1, characterized in that: The first reflux pipe and the second reflux pipe are both provided with valves.

3. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 2, characterized in that: The water adding structure includes an upper water adding component and a lower water adding component. The upper water adding component includes an upper water adding pipe. The upper water adding pipe is connected to the second water outlet pipe of the deaerator pump through the second water outlet main pipe. The second water outlet pipe is provided with a valve. The upper water adding pipe is provided with a valve and a flow regulating valve.

4. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 3, characterized in that: The lower water adding assembly comprises a lower water adding pipe, which is connected with the second water outlet pipe of the deaerator pump through the second water outlet main pipe, and a valve and a liquid level regulating valve are arranged on the lower water adding pipe.

5. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 4, characterized in that: The third outlet pipe is provided with a check valve and an outlet valve.

6. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 5, characterized in that: A limiting flow orifice is arranged on the first reflux pipe.

7. The method for cutting back a slag water treatment device of a pressurized gasification device according to claim 6, characterized in that: The second outlet pipe of the high-pressure grey water pump is communicated with the grey water heater, and a valve is arranged on the second outlet pipe.

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