Coal gasification black water circulation and black water waste heat recycling system

Abstract

The utility model relates to the technical field of coal chemical industry, in particular to a coal gasification black water circulation and black water waste heat recycling system. The coal gasification black water circulation and black water waste heat recycling system comprises a synthesis gas washing tower, a high-pressure flash tank, a low-pressure flash tank, a black water heat exchanger, a vacuum flash tank, a settling tank, a grey water tank, a low-pressure flash steam stripping tower and a high-pressure flash steam stripping tower. The coal gasification black water treated by the coal gasification black water circulation and black water waste heat recycling system disclosed by the utility model can be recycled as circulating water of a synthesis gas washing tower, so that the cyclic utilization of water resources is realized, the use of fresh water and the discharge of waste water are reduced, and the production cost and the environmental pressure are reduced. Meanwhile, the problem that a black water pipeline is scaled and blocked due to high temperature is solved, waste heat of the black water can be fully replaced for effective utilization, carbon is reduced, energy is saved, the purpose of cooling the black water is achieved, the cooling cost of a vacuum flash evaporation system is saved, and continuous and reliable economic benefits are created for enterprises.

Description

Technical Field

[0001] This utility model relates to the field of coal chemical technology, and in particular to a coal gasification black water circulation and black water waste heat recovery and utilization system. Background Technology

[0002] Coal gasification black water is a type of wastewater containing various impurities produced during the coal gasification process. It mainly contains fine particulate coal slag, carbon black, and other suspended solids, as well as small amounts of gasification reaction byproducts such as sulfides, ammonia nitrogen, phenols, cyanides, and other harmful substances.

[0003] Existing methods for treating black water from coal gasification primarily involve using sedimentation tanks and filters to settle or remove suspended solids. Alternatively, oxidants are used to oxidize and decompose organic matter and reducing agents in the water, reducing their toxicity and pollutant content. Microorganisms are also employed to convert biodegradable organic matter into carbon dioxide and water, removing nutrients such as ammonia nitrogen. However, due to the complex composition of coal gasification black water, containing various pollutants such as sulfides, ammonia nitrogen, phenols, and cyanides, these substances can inhibit microorganisms in the recycling system, affecting the biological treatment effect. They may also undergo chemical reactions during circulation, generating new, difficult-to-treat substances. Furthermore, calcium and magnesium ions and some dissolved salts in the high-temperature coal gasification black water easily form scale on the surfaces of equipment and pipes. This not only reduces heat transfer efficiency and increases energy consumption, but in severe cases, it can clog pipes, causing system load reduction or even forced shutdown for cleaning, and also results in the loss of significant amounts of waste heat from the black water. Current treatment methods struggle to solve the scaling and clogging problem of black water and cannot achieve waste heat recovery.

[0004] Therefore, it is necessary to develop a system and method for recycling black water from coal gasification and recovering waste heat from the black water to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a coal gasification black water circulation and black water waste heat recovery and utilization system to solve the problems of black water scaling and blockage and the inability to realize waste heat recovery and utilization.

[0006] This utility model provides a coal gasification black water circulation and black water waste heat recovery and utilization system, including a syngas scrubbing tower, a high-pressure flash tank, a low-pressure flash tank, a black water heat exchanger, a vacuum flash tank, a settling tank, an ash water tank, a low-pressure flash steam lifter, and a high-pressure flash steam lifter; a medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubbing tower, the upper end of the syngas scrubbing tower is connected to the syngas output pipeline, the lower end of the syngas scrubbing tower is connected to the high-pressure flash tank, the upper end of the high-pressure flash tank is connected to the high-pressure flash steam lifter, and the lower end of the high-pressure flash tank... The system is connected to the low-pressure flash tank, with its upper end connected to the low-pressure flash steam lift tower and its lower end connected to the tube-side inlet of the black water heat exchanger. The tube-side outlet of the black water heat exchanger is connected in series with the vacuum flash tank, whose lower end is connected to the settling tank. The upper clarified liquid overflow outlet of the settling tank is connected to the ash water tank, which is connected to the low-pressure flash steam lift tower. The lower end of the low-pressure flash steam lift tower is connected to the high-pressure flash steam lift tower, and the lower end of the high-pressure flash steam lift tower is connected to the syngas scrubbing tower.

[0007] Furthermore, the shell-side inlet of the black water heat exchanger is connected to the desalination chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger is connected to the desalination chilled water return pipeline.

[0008] Furthermore, it also includes a vacuum flash condenser, a vacuum flash separator, and a flash vacuum pump. The upper end of the vacuum flash separator is connected to the vacuum flash condenser, the vacuum flash condenser is connected to the vacuum flash separator, the lower end of the vacuum flash separator is connected to the ash water tank, the upper end of the vacuum flash separator is connected to the flash vacuum pump, the flash vacuum pump is connected to the two waste furnaces, and an air input pipe is connected to the connecting pipe between the vacuum flash separator and the flash vacuum pump.

[0009] Furthermore, the vacuum flash condenser is connected to the cooling water inlet pipe and the cooling water outlet pipe respectively for heat exchange.

[0010] Furthermore, an ash water pump is installed between the ash water tank and the low-pressure flash steam tower.

[0011] Furthermore, a deoxygenated water pump is installed between the low-pressure flash steam riser and the high-pressure flash steam riser.

[0012] Furthermore, a washing tower feed pump is provided between the high-pressure flash steam stripper and the syngas washing tower.

[0013] Furthermore, the upper end of the low-pressure flash steam tower is connected to a low-pressure flash condenser, and the low-pressure flash condenser is connected to a low-pressure flash steam output pipeline.

[0014] Furthermore, the low-pressure flash condenser is connected to the cooling water inlet pipe and the cooling water outlet pipe respectively for heat exchange.

[0015] Furthermore, shut-off valves are installed on the medium-pressure boiler water pipeline, the syngas pipeline, the syngas output pipeline, and the pipeline between two adjacent devices.

[0016] The method for recycling black water and recovering waste heat from coal gasification using the aforementioned coal gasification black water recycling and black water waste heat recovery system includes the following steps:

[0017] (S1) Medium-pressure boiler water and syngas from the previous section are input into the syngas scrubbing tower. After scrubbing, the upper end of the syngas scrubbing tower outputs syngas for conversion, and the lower end of the syngas scrubbing tower outputs high-temperature black water.

[0018] (S2) After the high-temperature black water enters the high-pressure flash tank (0.5Mpa), it undergoes preliminary gas-liquid separation to separate high-pressure flash steam (0.5Mpa, 158℃) and high-temperature black water (0.5Mpa, 158℃). The high-pressure flash steam is then transported to the high-pressure flash steam lifting tower via a pipeline.

[0019] (S3) The high-temperature black water is transported through a pipeline to the low-pressure flash tank (0.15Mpa, 130℃) for secondary gas-liquid separation, further separating the volatile components in the liquid to form low-pressure flash steam (0.15Mpa, 130℃) and high-temperature black water (0.15Mpa, 130℃). The low-pressure flash steam is transported through a pipeline to the low-pressure flash steam lifting tower.

[0020] (S4) High-temperature black water (130℃, 0.4MPa) is transported through a pipeline to the tube side of the black water heat exchanger. After exchanging heat with the desalinated chilled water in the shell side of the black water heat exchanger, the black water is significantly cooled (83℃, 0.4MPa).

[0021] (S5) The black water, after being significantly cooled, is transported through a pipeline to the vacuum flash tank (-0.05 MPa, 83°C), where it undergoes further gas-liquid separation by depressurization. This further separates the volatile components in the liquid to form vacuum flash vapor (-0.05 MPa, 83°C) and black water (-0.05 MPa, 83°C). The black water is then transported through a pipeline to the settling tank, and the clarified liquid at the top of the settling tank overflows from the upper clarified liquid overflow outlet into the ash water tank (atmospheric pressure, 80°C).

[0022] (S6) Ash water (atmospheric pressure, 80℃) is transported through pipeline to the low-pressure flash steam tower (atmospheric pressure, 100℃) for further flash separation to improve gas recovery efficiency and purify ash water, separating low-pressure flash steam (atmospheric pressure, 100℃) and ash water (atmospheric pressure, 100℃).

[0023] (S7) Subsequently, the ash water (atmospheric pressure, 100°C) is transported through pipeline to the high-pressure flash steam stripping tower (0.5Mpa, 150°C) for deep purification and separation, separating purified water and high-pressure flash steam. The high-pressure flash steam is transported to the shift stripping tower, and the purified water is transported through pipeline to the syngas scrubbing tower for recycling and syngas scrubbing.

[0024] The positive effects of this utility model are:

[0025] (1) The coal gasification black water circulation and black water waste heat recovery and utilization system of this utility model obtains purified water that meets the requirements through multi-level enterprise separation and purification.

[0026] (2) This utility model sets up a black water heat exchanger in the system and uses desalinated chilled water as the heat transfer carrier to extract heat from the black water and supply the heat to the lithium bromide unit in the plant to produce cold water for the production process. At the same time, it achieves the purpose of cooling the black water, reduces the operating load of the vacuum flash evaporation system, saves the power consumption of the vacuum pump, and saves the consumption of the circulating water system.

[0027] (3) The coal gasification black water circulation and black water waste heat recovery and utilization system described in this utility model has a simple structure and ingenious design, making it more suitable for promotion and application.

[0028] (4) The method of coal gasification black water circulation and black water waste heat recovery and utilization described in this utility model is simple, easy to implement, efficient and low cost.

[0029] (5) The coal gasification black water treated by the coal gasification black water circulation and black water waste heat recovery system described in this utility model can be reused as circulating water in the syngas scrubbing tower, realizing the recycling of water resources, reducing the intake of fresh water and the discharge of wastewater, and reducing production costs and environmental pressure. At the same time, it solves the problem of scaling and blockage of black water pipes caused by high temperature, and can also fully replace the waste heat of black water for effective utilization, reducing carbon emissions and saving energy. It also achieves the purpose of cooling black water, saving the cooling cost of the vacuum flash evaporation system, and creating continuous and reliable economic benefits for enterprises. Attached Figure Description

[0030] The accompanying drawings are provided to better understand this solution and do not constitute a limitation of this disclosure. Wherein:

[0031] Figure 1 This is a particle size distribution diagram of suspended solids in black water;

[0032] Figure 2 This is a schematic diagram of the coal gasification black water circulation and black water waste heat recovery and utilization system described in this utility model;

[0033] The components include: 1. Syngas scrubbing tower; 2. High-pressure flash tank; 3. Low-pressure flash tank; 4. Black water heat exchanger; 5. Vacuum flash tank; 6. Settling tank; 7. Ash water tank; 8. Low-pressure flash steam lift tower; 9. High-pressure flash steam lift tower; 10. Vacuum flash condenser; 11. Vacuum flash separator; 12. Flash vacuum pump; 13. Ash water pump; 14. Deoxygenated water pump; 15. Scrubber feed pump; and 16. Low-pressure flash condenser. Detailed Implementation

[0034] The exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0035] In one aspect, this utility model provides a coal gasification black water circulation and black water waste heat recovery system, including a syngas scrubbing tower 1, a high-pressure flash tank 2, a low-pressure flash tank 3, a black water heat exchanger 4, a vacuum flash tank 5, a settling tank 6, an ash water tank 7, a low-pressure flash steam lifter 8, a high-pressure flash steam lifter 9, a vacuum flash condenser 10, a vacuum flash separator 11, and a flash vacuum pump 12; a medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubbing tower 1, the upper end of the syngas scrubbing tower 1 is connected to the syngas output pipeline, the lower end of the syngas scrubbing tower 1 is connected to the high-pressure flash tank 2, the upper end of the high-pressure flash tank 2 is connected to the high-pressure flash steam lifter 9, and the lower end of the high-pressure flash tank 2 is connected to the... A low-pressure flash tank 3 is connected, with its upper end connected to a low-pressure flash steam stripping tower 8 and its lower end connected to the tube-side inlet of a black water heat exchanger 4. A vacuum flash tank 5 is connected in series with the tube-side outlet of the black water heat exchanger 4. The upper end of the vacuum flash tank 5 is connected to a vacuum flash condenser 10, which is connected to a vacuum flash separator 11. The lower end of the vacuum flash separator 11 is connected to an ash water tank 7, and its upper end is connected to a flash vacuum pump 12. The flash vacuum pump 12 is connected to two waste furnaces, and an air input pipe is connected to the connecting pipe between the vacuum flash separator 11 and the flash vacuum pump 12. The lower end of the vacuum flash tank 5 is connected to the settling tank 6. The upper clarified liquid overflow outlet of the settling tank 6 is connected to the ash water tank 7. The ash water tank 7 is connected to the low-pressure flash steam lifter 8. The upper end of the low-pressure flash steam lifter 8 is connected to the low-pressure flash condenser 16. The low-pressure flash condenser 16 is connected to the low-pressure flash steam output pipeline. The lower end of the low-pressure flash steam lifter 8 is connected to the high-pressure flash steam lifter 9. The lower end of the high-pressure flash steam lifter 9 is connected to the syngas scrubbing tower 1.

[0036] The shell-side inlet of the black water heat exchanger 4 is connected to the desalination chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalination chilled water return pipeline. The waste heat of the black water is then supplied to the lithium bromide unit in the plant to produce chilled water for use in the production process, simultaneously achieving the purpose of cooling the black water, reducing the operating load of the vacuum flash evaporation system, saving the power consumption of the vacuum pump, and saving the consumption of the circulating water system. The black water heat exchanger 4 of this invention is a shell-and-tube heat exchanger, which can provide good, continuous, and efficient heat exchange. The vacuum flash condenser 10 is connected to the cooling water inlet and outlet pipelines for heat exchange. The low-pressure flash condenser 16 is connected to the cooling water inlet and outlet pipelines for heat exchange. An ash water pump 13 is installed between the ash water tank 7 and the low-pressure flash steam riser 8; a deaerator pump 14 is installed between the low-pressure flash steam riser 8 and the high-pressure flash steam riser 9; and a scrubbing tower feed pump 15 is installed between the high-pressure flash steam riser 9 and the syngas scrubbing tower 1. Shut-off valves are installed on the medium-pressure boiler water pipeline, the syngas pipeline, the syngas output pipeline, and the pipelines between adjacent devices.

[0037] Secondly, this utility model provides a method for circulating and recovering waste heat from coal gasification black water using the aforementioned coal gasification black water circulation and waste heat recovery system, comprising the following steps:

[0038] (S1) Medium-pressure boiler water and syngas from the previous section are input into the syngas scrubbing tower 1. After scrubbing, the upper end of the syngas scrubbing tower 1 outputs syngas for conversion, and the lower end of the syngas scrubbing tower 1 outputs high-temperature black water.

[0039] (S2) After the high-temperature black water enters the high-pressure flash tank (0.5Mpa)2, it undergoes preliminary gas-liquid separation to separate high-pressure flash steam (0.5Mpa, 158℃) and high-temperature black water (0.5Mpa, 158℃). The high-pressure flash steam is transported to the high-pressure flash steam lifting tower 9 via pipeline.

[0040] (S3) The high-temperature black water is transported through a pipeline to the low-pressure flash tank (0.15Mpa, 130℃) 3 for secondary gas-liquid separation, further separating the volatile components in the liquid to form low-pressure flash steam (0.15Mpa, 130℃) and high-temperature black water (0.15Mpa, 130℃). The low-pressure flash steam is transported through a pipeline to the low-pressure flash steam lifting tower 8.

[0041] (S4) High-temperature black water (130℃, 0.4MPa) is transported through a pipeline to the tube side of the black water heat exchanger 4. After exchanging heat with the desalinated chilled water in the shell side of the black water heat exchanger 4, the black water is significantly cooled (83℃, 0.4MPa).

[0042] (S5) The black water after being significantly cooled is transported through a pipeline to the vacuum flash tank (-0.05Mpa, 83℃) 5, where it undergoes further gas-liquid separation by depressurization, further separating the volatile components in the liquid to form vacuum flash vapor (-0.05Mpa, 83℃) and black water (-0.05Mpa, 83℃). The black water is then transported through a pipeline to the settling tank 6, and the clarified liquid on the upper part of the settling tank 6 overflows from the upper clarified liquid overflow outlet into the ash water tank (atmospheric pressure, 80℃) 7.

[0043] (S6) Ash water (atmospheric pressure, 80℃) is transported through pipeline to the low-pressure flash steam tower (atmospheric pressure, 100℃) 8 for further flash separation to improve gas recovery efficiency and purify ash water, separating low-pressure flash steam (atmospheric pressure, 100℃) and ash water (atmospheric pressure, 100℃).

[0044] (S7) Subsequently, the grey water (atmospheric pressure, 100℃) is transported through pipeline to the high-pressure flash steam stripping tower (0.5Mpa, 150℃) 9 for deep purification and separation, separating purified water and high-pressure flash steam. The high-pressure flash steam is transported to the shift stripping tower, and the purified water is transported through pipeline to the syngas scrubbing tower 1 for recycling and syngas scrubbing.

[0045] Before studying the coal gasification black water circulation and black water waste heat recovery system, the following results were obtained from on-site sampling and testing of black water and scale solids:

[0046] The main results of the test on a bottle of black water sample taken on the afternoon of December 10, 2024 are as follows:

[0047] (1) pH value: pH = 8.89, alkaline;

[0048] (2) Density: 1.0016 g / ml;

[0049] (3) Solid content: 0.907%;

[0050] (4) The concentration of soluble particles in the filtrate is shown in Table 1 below:

[0051] Table 1. Concentration of soluble particles in the filtrate

[0052] element mass fraction / % Si 0.1720 Mg 0.0561 Ca 0.0128 Cl 0.0069 P 0.0064 S 0.0023 Fe 0.0013

[0053] (5) The chemical composition of solids in black water is shown in Table 2:

[0054] Table 2 Chemical composition of solids in black water

[0055]

[0056]

[0057] (6) Particle size distribution of suspended solids in black water, see Figure 1 ,from Figure 1 It can be seen that the particle size distribution is between 0.5 and 100 μm.

[0058] Based on the aforementioned black water test data, the coal gasification black water circulation and waste heat recovery system of Examples 1-4 were constructed. Shut-off valves can be installed at the beginning or end of the pipelines between each device in the system to handle emergencies in industrial production. Details will not be elaborated further in this invention; those skilled in the art can determine the appropriate locations for the shut-off valves based on experience.

[0059] Example 1

[0060] A coal gasification black water circulation and black water waste heat recovery and utilization system, see Figure 2 The system includes a syngas scrubbing tower 1, a high-pressure flash tank 2, a low-pressure flash tank 3, a black water heat exchanger 4, a vacuum flash tank 5, a settling tank 6, an ash water tank 7, a low-pressure flash steam lifter 8, a high-pressure flash steam lifter 9, a vacuum flash condenser 10, a vacuum flash separator 11, and a flash vacuum pump 12. Medium-pressure boiler water pipes and syngas pipes are connected to the syngas scrubbing tower 1. The upper end of the syngas scrubbing tower 1 is connected to the syngas output pipe, and the lower end of the syngas scrubbing tower 1 is connected to the high-pressure flash tank 2. The upper end of the high-pressure flash tank 2 is connected to the high-pressure flash steam lifter 9, and the lower end of the high-pressure flash tank 2 is connected to the low-pressure flash tank 3. The upper end of the low-pressure flash steam tower 8 is connected to the low-pressure flash tank 3. The lower end of the low-pressure flash tank 3 is connected to the tube-side inlet of the black water heat exchanger 4. The tube-side outlet of the black water heat exchanger 4 is connected in series with the vacuum flash tank 5. The upper end of the vacuum flash tank 5 is connected to the vacuum flash condenser 10. The vacuum flash condenser 10 is connected to the vacuum flash separator 11. The lower end of the vacuum flash separator 11 is connected to the ash water tank 7. The upper end of the vacuum flash separator 11 is connected to the flash vacuum pump 12. The flash vacuum pump 12 is connected to the two waste furnaces. An air input pipe is connected to the connecting pipe between the vacuum flash separator 11 and the flash vacuum pump 12. The lower end of the vacuum flash tank 5 is connected to the settling tank 6. The upper clarified liquid overflow outlet of the settling tank 6 is connected to the ash water tank 7. The ash water tank 7 is connected to the low-pressure flash steam riser 8. The upper end of the low-pressure flash steam riser 8 is connected to the low-pressure flash condenser 16. The low-pressure flash condenser 16 is connected to the low-pressure flash steam output pipeline. The lower end of the low-pressure flash steam riser 8 is connected to the high-pressure flash steam riser 9. The lower end of the high-pressure flash steam riser 9 is connected to the syngas scrubbing tower 1.

[0061] The shell-side inlet of the black water heat exchanger 4 is connected to the desalination chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalination chilled water return pipeline. The vacuum flash condenser 10 is connected to the cooling water inlet and outlet pipelines for heat exchange. The low-pressure flash condenser 16 is connected to the cooling water inlet and outlet pipelines for heat exchange. An ash water pump 13 is installed between the ash water tank 7 and the low-pressure flash steam lifter 8. A deaerator pump 14 is installed between the low-pressure flash steam lifter 8 and the high-pressure flash steam lifter 9. A scrubbing tower feed pump 15 is installed between the high-pressure flash steam lifter 9 and the syngas scrubbing tower 1. Shut-off valves are installed on the medium-pressure boiler water pipeline, the syngas pipeline, the syngas output pipeline, and the pipelines between adjacent devices.

[0062] Example 2

[0063] A coal gasification black water circulation and black water waste heat recovery system includes a syngas scrubbing tower 1, a high-pressure flash tank 2, a low-pressure flash tank 3, a black water heat exchanger 4, a vacuum flash tank 5, a settling tank 6, an ash water tank 7, a low-pressure flash steam riser 8, and a high-pressure flash steam riser 9. Medium-pressure boiler water pipes and syngas pipes are respectively connected to the syngas scrubbing tower 1. The upper end of the syngas scrubbing tower 1 is connected to the syngas output pipe, and the lower end of the syngas scrubbing tower 1 is connected to the high-pressure flash tank 2. The upper end of the high-pressure flash tank 2 is connected to the high-pressure flash steam riser 9, and the lower end of the high-pressure flash tank 2 is connected to the low-pressure flash steam riser 9. A low-pressure flash tank 3 is connected to a high-pressure flash steam riser 8 at its upper end, and to the tube-side inlet of a black water heat exchanger 4 at its lower end. A vacuum flash tank 5 is connected in series to the tube-side outlet of the black water heat exchanger 4. The lower end of the vacuum flash tank 5 is connected to a settling tank 6, and the upper clarified liquid overflow outlet of the settling tank 6 is connected to an ash water tank 7. The ash water tank 7 is connected to the low-pressure flash steam riser 8, and the lower end of the low-pressure flash steam riser 8 is connected to a high-pressure flash steam riser 9. The lower end of the high-pressure flash steam riser 9 is connected to a syngas scrubbing tower 1. The shell-side inlet of the black water heat exchanger 4 is connected to a desalination chilled water feedwater pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to a desalination chilled water return pipeline.

[0064] Example 3

[0065] A coal gasification black water circulation and black water waste heat recovery system includes a syngas scrubbing tower 1, a high-pressure flash tank 2, a low-pressure flash tank 3, a black water heat exchanger 4, a vacuum flash tank 5, a settling tank 6, an ash water tank 7, a low-pressure flash steam lifter 8, a high-pressure flash steam lifter 9, a vacuum flash condenser 10, a vacuum flash separator 11, and a flash vacuum pump 12. A medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubbing tower 1. The upper end of the syngas scrubbing tower 1 is connected to the syngas output pipeline, and the lower end of the syngas scrubbing tower 1 is connected to the high-pressure flash tank 2. The upper end of the high-pressure flash tank 2 is connected to the high-pressure flash steam lifter 9, and the lower end of the high-pressure flash tank 2 is connected to the low-pressure flash tank 3. The low-pressure flash tank 3 is connected at its upper end to the low-pressure flash steam stripping tower 8, and at its lower end to the tube-side inlet of the black water heat exchanger 4. The vacuum flash tank 5 is connected in series with the tube-side outlet of the black water heat exchanger 4. The upper end of the vacuum flash tank 5 is connected to the vacuum flash condenser 10, and the vacuum flash condenser 10 is connected to the vacuum flash separator 11. The lower end of the vacuum flash separator 11 is connected to the ash water tank 7, and the upper end of the vacuum flash separator 11 is connected to the flash vacuum pump 12. The flash vacuum pump 12 is connected to the two waste furnaces, and an air input pipe is connected to the connecting pipe between the vacuum flash separator 11 and the flash vacuum pump 12. The lower end of the vacuum flash evaporator 5 is connected to the settling tank 6, the upper clarified liquid overflow outlet of the settling tank 6 is connected to the ash water tank 7, the ash water tank 7 is connected to the low-pressure flash steam lifter 8, the lower end of the low-pressure flash steam lifter 8 is connected to the high-pressure flash steam lifter 9, and the lower end of the high-pressure flash steam lifter 9 is connected to the syngas scrubbing tower 1. The shell-side inlet of the black water heat exchanger 4 is connected to the desalination chilled water feed pipe, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalination chilled water return pipe. The vacuum flash condenser 10 is connected to the cooling water inlet pipe and the cooling water outlet pipe for heat exchange.

[0066] Example 4

[0067] A coal gasification black water circulation and black water waste heat recovery system includes a syngas scrubbing tower 1, a high-pressure flash tank 2, a low-pressure flash tank 3, a black water heat exchanger 4, a vacuum flash tank 5, a settling tank 6, an ash water tank 7, a low-pressure flash steam lifter 8, a high-pressure flash steam lifter 9, a vacuum flash condenser 10, a vacuum flash separator 11, and a flash vacuum pump 12. A medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubbing tower 1. The upper end of the syngas scrubbing tower 1 is connected to the syngas output pipeline, and the lower end of the syngas scrubbing tower 1 is connected to the high-pressure flash tank 2. The upper end of the high-pressure flash tank 2 is connected to the high-pressure flash steam lifter 9, and the lower end of the high-pressure flash tank 2 is connected to the low-pressure flash tank 3. The low-pressure flash tank 3 is connected at its upper end to the low-pressure flash steam stripping tower 8, and at its lower end to the tube-side inlet of the black water heat exchanger 4. The vacuum flash tank 5 is connected in series with the tube-side outlet of the black water heat exchanger 4. The upper end of the vacuum flash tank 5 is connected to the vacuum flash condenser 10, and the vacuum flash condenser 10 is connected to the vacuum flash separator 11. The lower end of the vacuum flash separator 11 is connected to the ash water tank 7, and the upper end of the vacuum flash separator 11 is connected to the flash vacuum pump 12. The flash vacuum pump 12 is connected to the two waste furnaces, and an air input pipe is connected to the connecting pipe between the vacuum flash separator 11 and the flash vacuum pump 12. The lower end of the vacuum flash tank 5 is connected to the settling tank 6. The upper clarified liquid overflow outlet of the settling tank 6 is connected to the ash water tank 7. The ash water tank 7 is connected to the low-pressure flash steam lifter 8. The lower end of the low-pressure flash steam lifter 8 is connected to the high-pressure flash steam lifter 9. The lower end of the high-pressure flash steam lifter 9 is connected to the syngas scrubbing tower 1. The shell-side inlet of the black water heat exchanger 4 is connected to the desalination chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalination chilled water return pipeline. The vacuum flash condenser 10 is connected to the cooling water inlet pipeline and the cooling water outlet pipeline for heat exchange. An ash water pump 13 is installed between the ash water tank 7 and the low-pressure flash steam lifter 8. A deoxygenated water pump 14 is installed between the low-pressure flash steam lifter 8 and the high-pressure flash steam lifter 9. A scrubbing tower feed pump 15 is installed between the high-pressure flash steam lifter 9 and the syngas scrubbing tower 1.

[0068] Example 5

[0069] The method for circulating black water and recovering waste heat from coal gasification using the black water circulation and waste heat recovery system described in Example 1 includes the following steps:

[0070] (S1) Medium-pressure boiler water and syngas from the previous section are input into the syngas scrubbing tower 1. After scrubbing, the upper end of the syngas scrubbing tower 1 outputs syngas for conversion, and the lower end of the syngas scrubbing tower 1 outputs high-temperature black water.

[0071] (S2) After the high-temperature black water enters the high-pressure flash tank (0.5Mpa)2, it undergoes preliminary gas-liquid separation to separate high-pressure flash steam (0.5Mpa, 158℃) and high-temperature black water (0.5Mpa, 158℃). The high-pressure flash steam is transported to the high-pressure flash steam lifting tower 9 via pipeline.

[0072] (S3) The high-temperature black water is transported through a pipeline to the low-pressure flash tank (0.15Mpa, 130℃) 3 for secondary gas-liquid separation, further separating the volatile components in the liquid to form low-pressure flash steam (0.15Mpa, 130℃) and high-temperature black water (0.15Mpa, 130℃). The low-pressure flash steam is transported through a pipeline to the low-pressure flash steam lifting tower 8.

[0073] (S4) High-temperature black water (130℃, 0.4MPa) is transported through a pipeline to the tube side of the black water heat exchanger 4. After exchanging heat with the desalinated chilled water in the shell side of the black water heat exchanger 4, the black water is significantly cooled (83℃, 0.4MPa); the temperature of the desalinated chilled water is approximately 70℃, and the pressure is 0.4~0.5MPa.

[0074] (S5) The black water, after being significantly cooled, is transported through a pipeline to the vacuum flash tank (-0.05Mpa, 83℃) 5, where it undergoes further gas-liquid separation by depressurization, further separating the volatile components in the liquid to form vacuum flash vapor (-0.05Mpa, 83℃) and black water (-0.05Mpa, 83℃).

[0075] The vacuum flash vapor (-0.05 MPa, 83°C) is condensed by the vacuum flash condenser 10, where water vapor and low-boiling-point organic gases are converted into liquid (-0.05 MPa, 25°C). This liquid then enters the vacuum flash separator 11, where it is further separated into vacuum flash vapor (-0.05 MPa, 25°C) and a small amount of water (-0.05 MPa, 25°C). The small amount of water enters the ash water tank (at atmospheric pressure, 80°C). The vacuum flash vapor (-0.05 MPa, 25°C) is mixed with air and then transported by the flash vacuum pump 12 to the two waste furnaces for utilization.

[0076] The black water is transported to the settling tank 6 through a pipeline, and the clarified liquid in the upper layer of the settling tank 6 overflows from the upper clarified liquid overflow outlet of the settling tank 6 into the gray water tank (atmospheric pressure, 80℃) 7.

[0077] (S6) Ash water (atmospheric pressure, 80℃) is transported through pipeline to the low-pressure flash steam tower (atmospheric pressure, 100℃) 8 for further flash separation to improve gas recovery efficiency and purify ash water, separating low-pressure flash steam (atmospheric pressure, 100℃) and ash water (atmospheric pressure, 100℃).

[0078] (S7) Subsequently, the grey water (atmospheric pressure, 100℃) is transported through pipeline to the high-pressure flash steam stripping tower (0.5Mpa, 150℃) 9 for deep purification and separation, separating purified water and high-pressure flash steam. The high-pressure flash steam is transported to the shift stripping tower, and the purified water is transported through pipeline to the syngas scrubbing tower 1 for recycling and syngas scrubbing.

[0079] The coal gasification black water circulation and waste heat recovery system of this invention utilizes multi-stage enterprise separation and purification to ultimately obtain purified water that meets the requirements. Simultaneously, a black water heat exchanger is installed within the system, using desalinated chilled water as the heat transfer medium to extract heat from the black water. This heat is then supplied to the lithium bromide unit within the plant to produce chilled water for use in the production process, thereby achieving the purpose of cooling the black water, reducing the operating load of the vacuum flash evaporation system, saving energy consumption of the vacuum pump, and saving on the consumption of the circulating water system. The coal gasification black water circulation and waste heat recovery system of this invention has a simple structure and ingenious design, making it more suitable for widespread application. The method of coal gasification black water circulation and waste heat recovery is simple, easy to implement, highly efficient, and low in cost. The coal gasification black water treated by the coal gasification black water circulation and waste heat recovery system described in this utility model can be reused as circulating water in the syngas scrubbing tower, realizing the recycling of water resources, reducing the intake of fresh water and the discharge of wastewater, and reducing production costs and environmental pressure. At the same time, it solves the problem of scaling and blockage of black water pipes caused by high temperature, and can also fully replace the waste heat of black water for effective utilization, reducing carbon emissions and saving energy. It also achieves the purpose of cooling black water, saving the cooling cost of the vacuum flash evaporation system, and creating continuous and reliable economic benefits for enterprises.

[0080] It should be understood that the steps of the coal gasification black water recycling and black water waste heat recovery system and method described above can be rearranged, added, or deleted. This utility model does not impose any limitations on the results achieved as long as the desired outcome of the technical solution disclosed herein can be achieved.

[0081] The specific embodiments described above do not constitute a limitation on the scope of protection disclosed in this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection disclosed in this utility model.

Claims

1. A coal gasification black water circulation and black water waste heat recovery and utilization system, characterized in that: The system includes a syngas scrubbing tower (1), a high-pressure flash tank (2), a low-pressure flash tank (3), a black water heat exchanger (4), a vacuum flash tank (5), a settling tank (6), an ash water tank (7), a low-pressure flash steam lifter (8), and a high-pressure flash steam lifter (9). The medium-pressure boiler water pipeline and the syngas pipeline are respectively connected to the syngas scrubbing tower (1). The upper end of the syngas scrubbing tower (1) is connected to the syngas output pipeline, and the lower end of the syngas scrubbing tower (1) is connected to the high-pressure flash tank (2). The upper end of the high-pressure flash tank (2) is connected to the high-pressure flash steam lifter (9), and the lower end of the high-pressure flash tank (2) is connected to the low-pressure flash tank (3). The upper end of the low-pressure flash tank (3) is connected to the low-pressure flash steam lifter (8), the lower end of the low-pressure flash tank (3) is connected to the tube-side inlet of the black water heat exchanger (4), the tube-side outlet of the black water heat exchanger (4) is connected in series with the vacuum flash tank (5), the lower end of the vacuum flash tank (5) is connected to the settling tank (6), the upper clarified liquid overflow outlet of the settling tank (6) is connected to the ash water tank (7), the ash water tank (7) is connected to the low-pressure flash steam lifter (8), the lower end of the low-pressure flash steam lifter (8) is connected to the high-pressure flash steam lifter (9), and the lower end of the high-pressure flash steam lifter (9) is connected to the syngas scrubbing tower (1).

2. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: The shell-side inlet of the black water heat exchanger (4) is connected to the desalination chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger (4) is connected to the desalination chilled water return pipeline.

3. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: It also includes a vacuum flash condenser (10), a vacuum flash separator (11), and a flash vacuum pump (12). The upper end of the vacuum flash separator (5) is connected to the vacuum flash condenser (10), the vacuum flash condenser (10) is connected to the vacuum flash separator (11), the lower end of the vacuum flash separator (11) is connected to the ash water tank (7), the upper end of the vacuum flash separator (11) is connected to the flash vacuum pump (12), the flash vacuum pump (12) is connected to the two waste furnaces, and an air input pipe is connected to the connecting pipe between the vacuum flash separator (11) and the flash vacuum pump (12).

4. The coal gasification black water recycling and black water waste heat recovery system according to claim 3, characterized in that: The vacuum flash condenser (10) is connected to the cooling water inlet pipe and the cooling water outlet pipe respectively for heat exchange.

5. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: An ash water pump (13) is provided between the ash water tank (7) and the low-pressure flash steam tower (8).

6. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: A deoxygenated water pump (14) is provided between the low-pressure flash steam riser (8) and the high-pressure flash steam riser (9).

7. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: A washing tower feed pump (15) is provided between the high-pressure flash steam stripping tower (9) and the syngas washing tower (1).

8. The coal gasification black water recycling and black water waste heat recovery system according to claim 1, characterized in that: The upper end of the low-pressure flash steam tower (8) is connected to the low-pressure flash condenser (16), and the low-pressure flash condenser (16) is connected to the low-pressure flash steam output pipeline.

9. The coal gasification black water recycling and black water waste heat recovery system according to claim 8, characterized in that: The low-pressure flash condenser (16) is connected to the cooling water inlet pipe and the cooling water outlet pipe respectively for heat exchange.

10. The coal gasification black water recycling and black water waste heat recovery system of claim 1, wherein: The medium-pressure boiler water pipeline, the syngas pipeline, the syngas output pipeline, and the pipeline between two adjacent devices are equipped with shut-off valves.

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