A zero-discharge system for treating coal gasification ash water
By designing a zero-emission system for gasified ash water treatment and adopting two-stage flash and evaporation treatment technologies, the equipment blockage and water pollution caused by the accumulation of salt in the ash water is solved, and zero emissions of slag water and resource recycling are achieved, reducing cooling Water demand improves energy utilization efficiency.
Patent Information
- Application Number
- CN202110271704.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-12
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2041-03-12
AI Technical Summary
The accumulation of salt in the process ash water generated in the gasification cooling process leads to the scaling of the equipment, which requires some high-salt ash water to be discharged, wasting water resources and causing pollution. At the same time, a large amount of cooling water is required for flash evaporation operations, and the air separation system produces polluted nitrogen. Outer discharge.
A zero-emission system for gasified ash water treatment was designed, using two stages of flash evaporation to treat slag water, which was divided into two channels of treatment through precipitation, one was deoxygenated and heated to be sent to the scrubber, the other was evaporated and recovered salt, and the steam was cooled and separated. The treatment is used as process water recovery, combining vacuum and medium-pressure flash technology to achieve zero discharge of slag water, and uses air-divided waste gas to replace cooling water to reduce energy consumption.
It realizes zero-emission treatment and resource recycling of slag water, avoids equipment blockage and water pollution, reduces cooling water demand, and improves energy utilization efficiency.
Smart Images
Figure CN112811703B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of water treatment and relates to a zero-discharge system for treating coal gasification ash water. Background Art
[0002] In the coal gasification quenching process technology, the synthesis gas produced by the gasifier needs to be washed before it can enter the downstream system. During the washing process, a large amount of process ash water is generated, which contains a large amount of salt and acidic gases dissolved in the ash water. In order to recycle this part of the ash water, all the ash water slag water is usually sent to the preliminary water treatment unit for flash evaporation to remove the acidic gas, and then sedimentation and filtration are used to remove solid particles before reuse. However, after long-term circulation, the salt in the ash water system will accumulate, and some calcium and magnesium ions will easily form precipitation, which will cause scaling and clogging of the equipment. Therefore, some high-salt ash water needs to be discharged directly, wasting water resources and causing certain water pollution. In addition, the flash evaporation operation in the preliminary water treatment unit requires a vacuum pump, and the vacuum flash gas needs to be condensed, which requires a large amount of cooling water to provide sufficient cooling capacity to meet the process requirements. Gasification devices are usually equipped with air separation systems. During the production process, air separation produces a large amount of polluted nitrogen that is discharged into the atmosphere. The temperature of the polluted nitrogen is very low compared to the flash gas of gasification. Therefore, the polluted nitrogen can be used as a cooling source to provide cooling for the flash gasification. This can effectively utilize the waste gas, turn waste into treasure, and realize the cascade utilization of energy.
[0003] Therefore, it is necessary to develop a zero-discharge grey water treatment device to solve the above problems. Summary of the Invention
[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a zero-discharge system for treating coal gasification ash water, which can achieve zero-discharge treatment of slag water and simultaneously realize resource recovery.
[0005] To achieve the above-mentioned purpose, the zero-emission system for treating coal gasification ash water of the present invention comprises a slag water input pipeline, a medium-pressure flash tank, a vacuum flash tank, a clarifier, an evaporation furnace, a deaerator, an evaporative cooler, an evaporative liquid separator, an ash water heater, a medium-pressure flash cooler, a medium-pressure flash liquid separator, a vacuum flash cooler, a vacuum flash liquid separator and a vacuum filter;
[0006] The slag water input pipeline is connected to the inlet of the medium-pressure flash tank, the liquid outlet at the bottom of the medium-pressure flash tank is connected to the inlet of the vacuum flash tank, and the liquid outlet at the bottom of the vacuum flash tank is connected to the inlet of the clarification tank;
[0007] The outlet on the side of the clarifier is divided into two routes, one of which is connected to the inlet of the evaporator, and the other is connected to the inlet of the deaerator. The steam outlet of the evaporator is connected to the inlet of the evaporation separator through the evaporative cooler, and the process water outlet of the evaporation separator is connected to the inlet of the deaerator. The outlet of the deaerator is connected to the external scrubber through the heat absorption side of the ash water heater.
[0008] The gas outlet at the top of the medium-pressure flash tank is connected to the inlet of the medium-pressure flash separator tank through the heat release side of the ash water heater and the medium-pressure flash cooler, and the water outlet of the medium-pressure flash tank is connected to the inlet of the deaerator;
[0009] The gas outlet at the top of the vacuum flash tank is connected to the inlet of the vacuum flash separator tank through the vacuum flash cooler, and the liquid outlet of the vacuum flash separator tank is connected to the inlet of the clarifier tank;
[0010] The outlet at the bottom of the clarification tank is connected to the inlet of the clarification tank through a vacuum filter.
[0011] The outlet on the side of the clarifier tank is divided into two paths after passing through the gray water tank and the gray water overflow pump.
[0012] The process water outlet of the evaporation separator is connected to the inlet of the deaerator through a process water circulation pump.
[0013] The outlet of the deaerator is connected to the external scrubber through the high-pressure ash water pump and the heat absorption side of the ash water heater.
[0014] The liquid outlet of the vacuum flash separation tank is connected to the inlet of the clarification tank through the vacuum flash condensate pump.
[0015] The gas outlet of the vacuum flash separation tank is communicated with the inlet of a vacuum pump.
[0016] The outlet at the bottom of the clarifier is connected to the inlet of the clarifier through the clarifier underflow pump and the vacuum filter.
[0017] The liquid outlet at the bottom of the vacuum flash tank is connected to the inlet of the clarification tank through the vacuum flash black water pump.
[0018] The utility model further comprises a make-up water pipeline, wherein the make-up water pipeline is connected with the inlet of the deaerator.
[0019] It also includes an electric control cabinet, wherein the electric control cabinet is connected to the power interface of the evaporation furnace.
[0020] The present invention has the following beneficial effects:
[0021] The zero-emission system for treating coal gasification ash water of the present invention adopts a two-stage flash evaporation method to remove the synthesis gas in the slag water during specific operation, and then the treated slag water is precipitated and divided into two paths. One path is sent to an external washing tower after deoxygenation by a deaerator and heating by a wastewater heater, and the other path enters an evaporation furnace for evaporation. The salt obtained by evaporation is directly recovered, and the steam generated by evaporation is recovered as process water after cooling and liquid separation treatment, so as to achieve zero-emission treatment of the slag water and the recycling and reuse of the slag water. The system has a simple structure, convenient operation and strong performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a structural schematic diagram of the present invention.
[0023] Among them, 1 is a medium-pressure flash tank, 2 is a vacuum flash tank, 3 is a vacuum flash black water pump, 4 is a clarifier, 5 is a clarifier underflow pump, 6 is an ash water tank, 7 is an ash water overflow pump, 8 is a vacuum flash cooler, 9 is a vacuum flash separator tank, 10 is a vacuum pump, 11 is a vacuum flash condensate pump, 12 is a vacuum filter, 13 is a deaerator, 14 is a high-pressure ash water pump, 15 is an ash water heater, 16 is a medium-pressure flash cooler, 17 is a medium-pressure flash separator tank, 18 is an evaporator, 19 is an evaporative cooler, 20 is an evaporative separator tank, and 21 is a process water circulation pump. DETAILED DESCRIPTION
[0024] The present invention is described in further detail below with reference to the accompanying drawings:
[0025] refer to Figure 1The zero-emission system for treating coal gasification ash water of the present invention comprises a slag water input pipeline, a medium-pressure flash tank 1, a vacuum flash tank 2, a clarifier 4, an evaporator 18, a deaerator 13, an evaporative cooler 19, an evaporative liquid separator 20, an ash water heater 15, a medium-pressure flash cooler 16, a medium-pressure flash liquid separator 17, a vacuum flash cooler 8, a vacuum flash liquid separator 9 and a vacuum filter 12; the slag water input pipeline is connected to the inlet of the medium-pressure flash tank 1, the liquid outlet at the bottom of the medium-pressure flash tank 1 is connected to the inlet of the vacuum flash tank 2, and the liquid outlet at the bottom of the vacuum flash tank 2 is connected to the inlet of the clarifier 4; the outlet on the side of the clarifier 4 is divided into two routes, one of which is connected to the inlet of the evaporator 18, and the other is connected to the inlet of the deaerator 13. The evaporator 18 The steam outlet is connected to the inlet of the evaporative separator tank 20 through the evaporative cooler 19, the process water outlet of the evaporative separator tank 20 is connected to the inlet of the deaerator 13, and the outlet of the deaerator 13 is connected to the external washing tower through the heat absorption side of the ash water heater 15; the gas outlet at the top of the medium-pressure flash tank 1 is connected to the inlet of the medium-pressure flash separator tank 17 through the heat release side of the ash water heater 15 and the medium-pressure flash cooler 16, and the water outlet of the medium-pressure flash tank 1 is connected to the inlet of the deaerator 13; the gas outlet at the top of the vacuum flash tank 2 is connected to the inlet of the vacuum flash separator tank 9 through the vacuum flash cooler 8, and the liquid outlet of the vacuum flash separator tank 9 is connected to the inlet of the clarification tank 4; the outlet at the bottom of the clarification tank 4 is connected to the inlet of the clarification tank 4 through the vacuum filter 12.
[0026] Specifically, the outlet on the side of the clarifier 4 is divided into two paths after passing through the ash water tank 6 and the ash water overflow pump 7; the process water outlet of the evaporation separator 20 is connected to the inlet of the deaerator 13 through the process water circulation pump 21; the outlet of the deaerator 13 is connected to the external washing tower through the high-pressure ash water pump 14 and the heat absorption side of the ash water heater 15; the liquid outlet of the vacuum flash separator 9 is connected to the inlet of the clarifier 4 through the vacuum flash condensate pump 11; the gas outlet of the vacuum flash separator 9 is connected to the inlet of the vacuum pump 10; the outlet at the bottom of the clarifier 4 is connected to the inlet of the clarifier 4 through the clarifier underflow pump 5 and the vacuum filter 12; the liquid outlet at the bottom of the vacuum flash tank 2 is connected to the inlet of the clarifier 4 through the vacuum flash black water pump 3.
[0027] The present invention further comprises a make-up water pipeline, wherein the make-up water pipeline is connected to the inlet of the deaerator 13, and fresh water is replenished through the make-up water pipeline.
[0028] The present invention further comprises an electric control cabinet, wherein the electric control cabinet is connected to a power interface of the evaporation furnace 18 , wherein the evaporation furnace 18 uses electric heating to perform evaporation and is controlled by the electric control cabinet.
[0029] The specific work of the present invention is:
[0030] The vaporized slag water enters the medium-pressure flash tank 1 for flash evaporation. The synthesis gas produced by flash evaporation is cooled by the ash water heater 15 and the medium-pressure flash cooler 16, and then enters the medium-pressure flash separator 17 for liquid separation. The synthesis gas output from the medium-pressure flash separator 17 enters the external sulfur recovery device, and the liquid output from the medium-pressure flash separator 17 enters the deaerator 13.
[0031] The liquid output from the bottom of the medium-pressure flash tank 1 enters the vacuum flash tank 2 for vacuum flash evaporation, wherein the gas output from the vacuum flash tank 2 is cooled by the vacuum flash cooler 8 and then enters the vacuum flash separator 9 for separation. The gas discharged from the vacuum flash separator 9 is discharged by the vacuum pump 10. The liquid output from the vacuum flash separator 9 enters the clarification tank 4. The liquid output from the bottom of the vacuum flash tank 2 enters the clarification tank 4, and the liquid is clarified in the clarification tank 4. The supernatant output from the clarification tank 4 is divided into two paths after passing through the gray water tank 6 and the gray water overflow pump 7. One path enters the deaerator 13, and the other path enters the evaporation furnace 18 for evaporation.
[0032] The steam generated by the evaporation furnace 18 is cooled by the evaporation cooler 19 and then enters the evaporation separator 20, wherein the gas output by the evaporation separator 20 is discharged, and the liquid discharged from the evaporation separator 20 enters the deaerator 13 through the process water circulation pump 21, and the sediment discharged from the bottom of the clarification tank 4 enters the vacuum filter 12 through the underflow pump 5 of the clarification tank 4 for filtration, wherein the filter cake obtained by filtration is transported out, and the filtered liquid is returned to the clarification tank 4.
[0033] After being deoxygenated, the water in the deaerator 13 enters the ash water heater 15 through the high-pressure ash water pump 14 for heat exchange and temperature increase, and then enters the external washing tower.
[0034] It should be noted that the present invention can achieve zero wastewater discharge from the coal gasification water treatment system, and the process water can be 100% recycled. At the same time, the salt in the gray water can also generate economic value after concentration and subsequent treatment. At the same time, the air separation waste gas nitrogen (20°C) is used to replace the circulating cooling water of all coolers, greatly reducing the scale of the circulating cooling water station and low energy consumption.
Claims
1. A zero-emission system for treating coal gasification ash water, characterized in that: It comprises a slag water input pipeline, a medium-pressure flash tank (1), a vacuum flash tank (2), a clarifier (4), an evaporator (18), a deaerator (13), an evaporative cooler (19), an evaporative liquid separator tank (20), an ash water heater (15), a medium-pressure flash cooler (16), a medium-pressure flash liquid separator tank (17), a vacuum flash cooler (8), a vacuum flash liquid separator tank (9) and a vacuum filter (12); The slag water input pipeline is connected to the inlet of the medium-pressure flash tank (1), the liquid outlet at the bottom of the medium-pressure flash tank (1) is connected to the inlet of the vacuum flash tank (2), and the liquid outlet at the bottom of the vacuum flash tank (2) is connected to the inlet of the clarification tank (4); The outlet on the side of the clarification tank (4) is divided into two paths, one of which is connected to the inlet of the evaporation furnace (18), and the other is connected to the inlet of the deaerator (13). The steam outlet of the evaporation furnace (18) is connected to the inlet of the evaporation liquid separation tank (20) through the evaporation cooler (19), the process water outlet of the evaporation liquid separation tank (20) is connected to the inlet of the deaerator (13), and the outlet of the deaerator (13) is connected to the external washing tower through the heat absorption side of the gray water heater (15); The gas outlet at the top of the medium-pressure flash tank (1) is connected to the inlet of the medium-pressure flash separator tank (17) through the heat release side of the ash water heater (15) and the medium-pressure flash cooler (16), and the water outlet of the medium-pressure flash tank (1) is connected to the inlet of the deaerator (13); The gas outlet at the top of the vacuum flash tank (2) is connected to the inlet of the vacuum flash liquid separator (9) via the vacuum flash cooler (8), and the liquid outlet of the vacuum flash liquid separator (9) is connected to the inlet of the clarification tank (4); The outlet at the bottom of the clarification tank (4) is connected to the inlet of the clarification tank (4) via a vacuum filter (12); The outlet on the side of the clarification tank (4) is divided into two paths after passing through the gray water tank (6) and the gray water overflow pump (7); The process water outlet of the evaporation and separation tank (20) is connected to the inlet of the deaerator (13) via a process water circulation pump (21).
2. The zero-emission system for treating coal gasification ash water according to claim 1 is characterized in that: The outlet of the deaerator (13) is connected to the external washing tower via the high-pressure ash water pump (14) and the heat absorption side of the ash water heater (15).
3. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: The liquid outlet of the vacuum flash separation tank (9) is connected to the inlet of the clarification tank (4) via the vacuum flash condensate pump (11).
4. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: The gas outlet of the vacuum flash separation tank (9) is connected to the inlet of the vacuum pump (10).
5. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: The outlet at the bottom of the clarification tank (4) is connected to the inlet of the clarification tank (4) via the clarification tank underflow pump (5) and the vacuum filter (12).
6. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: The liquid outlet at the bottom of the vacuum flash tank (2) is connected to the inlet of the clarification tank (4) through the vacuum flash black water pump (3).
7. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: It also includes a make-up water pipeline, wherein the make-up water pipeline is connected to the inlet of the deaerator (13).
8. The zero-emission system for treating coal gasification ash water according to claim 1, characterized in that: It also includes an electric control cabinet, wherein the electric control cabinet is connected to a power interface of the evaporation furnace (18).