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

Abstract

The invention 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 and method. 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 circulating and black water waste heat recycling system can be reused 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] The present invention relates to the technical field of coal chemical engineering, and particularly relates to a coal gasification black water circulation and black water waste heat recovery and utilization system and method. Background Art

[0002] Coal gasification black water is a kind of wastewater containing various impurities generated during the coal gasification process. It mainly contains fine particulate coal cinder, carbon black and other solid suspended matters, and also contains a small amount of by-products of gasification reactions, such as harmful substances like sulfides, ammonia nitrogen, phenols, cyanides, etc.

[0003] The existing treatment methods for coal gasification black water mainly use equipment such as sedimentation tanks and filters to precipitate or filter out solid suspended matters. Or use oxidants to oxidize and decompose organic substances and reducing substances in the water to reduce their toxicity and pollutant content. There is also the help of the action of microorganisms to convert biodegradable organic substances in the water into carbon dioxide and water to remove nutrients such as ammonia nitrogen. However, due to the complex composition of coal gasification black water, which contains various pollutants such as sulfides, ammonia nitrogen, phenols, cyanides, etc., these substances will have an inhibitory effect on the microorganisms in the recycling system, affecting the biological treatment effect, and may also undergo chemical reactions during the recycling process to generate new substances that are difficult to treat. In addition, calcium, magnesium ions and some soluble salts in the high-temperature coal gasification black water are prone to form scale on the surface of equipment and pipelines, which will not only reduce the heat transfer efficiency, increase energy consumption, but also seriously block the pipelines when severe, resulting in system load reduction, and even forced shutdown for cleaning, and also cause a large amount of waste heat of black water to be lost. The treatment methods of the prior art are difficult to solve the problem of black water scaling and blockage, and cannot realize waste heat recovery and utilization.

[0004] Therefore, it is necessary to develop a coal gasification black water circulation and black water waste heat recovery and utilization system and method to solve the above problems. Summary of the Invention

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

[0006] The present invention provides a coal gasification black water circulation and black water waste heat recovery and utilization system and method.

[0007] Among them, the coal gasification black water circulation and black water waste heat recovery and utilization system includes 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 stripping tower and a high-pressure flash steam stripping tower; 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 a 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 stripping tower. The lower end of the high-pressure flash tank is connected to the low-pressure flash tank. The upper end of the low-pressure flash tank is connected to the low-pressure flash steam stripping tower. The lower end of the low-pressure flash tank is 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. The lower end of the vacuum flash tank is connected to the settling tank. The upper clarified liquid overflow outlet of the settling tank is connected to the ash water tank. The ash water tank is connected to the low-pressure flash steam stripping tower. The lower end of the low-pressure flash steam stripping tower is connected to the high-pressure flash steam stripping tower. The lower end of the high-pressure flash steam stripping tower is connected to the syngas scrubbing tower.

[0008] Furthermore, the shell side inlet of the black water heat exchanger is connected to a desalted chilled water feed pipeline, and the shell side outlet of the black water heat exchanger is connected to a desalted chilled water return pipeline.

[0009] Furthermore, it also includes a vacuum flash condenser, a vacuum flash separation tank and a flash vacuum pump. The upper end of the vacuum flash tank is connected to the vacuum flash condenser. The vacuum flash condenser is connected to the vacuum flash separation tank. The lower end of the vacuum flash separation tank is connected to the ash water tank. The upper end of the vacuum flash separation tank is connected to the flash vacuum pump. The flash vacuum pump is connected to a two-waste furnace. An air input pipeline is connected to the connecting pipeline between the vacuum flash separation tank and the flash vacuum pump.

[0010] Furthermore, the vacuum flash condenser is respectively connected to a cooling water inlet pipeline and a cooling water outlet pipeline for heat exchange.

[0011] Furthermore, a ash water pump is arranged between the ash water tank and the low-pressure flash steam stripping tower.

[0012] Furthermore, a deaerating water pump is arranged between the low-pressure flash steam stripping tower and the high-pressure flash steam stripping tower.

[0013] Furthermore, a scrubbing tower feed pump is arranged between the high-pressure flash steam stripping tower and the syngas scrubbing tower.

[0014] Furthermore, the upper end of the low-pressure flash steam stripping 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.

[0015] Further, the low-pressure flash condenser is respectively connected to the cooling water inlet pipe and the cooling water outlet pipe for heat exchange.

[0016] A method for gasification black water circulation and black water waste heat recovery and utilization using the above gasification black water circulation and black water waste heat recovery and utilization system includes the following steps:

[0017] (S1) Input medium-pressure boiler water and syngas from the previous section into the syngas scrubber. After washing, the syngas is output from the upper end of the syngas scrubber to go to conversion, and the high-temperature black water is output from the lower end of the syngas scrubber;

[0018] (S2) After the high-temperature black water enters the high-pressure flash tank (0.5 Mpa), preliminary gas-liquid separation is carried out to separate high-pressure flash steam (0.5 Mpa, 158 °C) and high-temperature black water (0.5 Mpa, 158 °C). Among them, the high-pressure flash steam is transported through a pipeline to the high-pressure flash steam stripping tower;

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

[0020] (S4) The high-temperature black water (130 °C, 0.4 MPa) is transported through a pipeline to the tube side of the black water heat exchanger and exchanges heat with the desalted chilled water in the shell side of the black water heat exchanger, and the black water is cooled significantly (83 °C, 0.4 MPa);

[0021] (S5) The significantly cooled black water is transported through a pipeline to the vacuum flash tank (-0.05 Mpa, 83 °C), and gas-liquid separation is further carried out by means of pressure reduction to further separate the volatile components in the liquid to form vacuum flash steam (-0.05 Mpa, 83 °C) and black water (-0.05 Mpa, 83 °C). Among them, the black water is transported through a pipeline to the settling tank, and the upper clarified liquid in the settling tank overflows from the upper clarified liquid overflow outlet of the settling tank and enters the ash water tank (atmospheric pressure, 80 °C);

[0022] (S6) The ash water (atmospheric pressure, 80 °C) is transported through a pipeline to the low-pressure flash steam stripping tower (atmospheric pressure, 100 °C), and further flash separation is carried out to improve the gas recovery efficiency and purify the ash water, separating low-pressure flash steam (atmospheric pressure, 100 °C) and ash water (atmospheric pressure, 100 °C);

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

[0024] Positive effects of the present invention:

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

[0026] (2) The present invention sets a black water heat exchanger in the system and uses desalted chilled water as the heat transfer medium to extract the heat of the black water, supplying the heat to the lithium bromide unit in the factory to produce chilled 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 flashing system, saves the power consumption of the vacuum pump, and saves the consumption of the circulating water system.

[0027] (3) The structure of the coal gasification black water circulation and black water waste heat recovery and utilization system of the present invention is simple and ingeniously conceived, and is more suitable for popularization and application.

[0028] (4) The method of coal gasification black water circulation and black water waste heat recovery and utilization of the present invention is simple, easy to implement, highly 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 and utilization system of the present invention can be reused as the circulating water for the syngas scrubbing column, realizing the recycling of water resources, reducing the consumption of fresh water and the discharge of wastewater, reducing production costs and environmental pressure. At the same time, it solves the problem of scale blockage in the black water pipeline caused by high temperature, can fully extract the waste heat of the black water for effective utilization, reduce carbon and save energy, and at the same time achieve the purpose of cooling the black water, saving the cooling cost of the vacuum flashing system, and creating continuous and reliable economic benefits for the enterprise. Description of the Drawings

[0030] The drawings are used to better understand the present solution and do not constitute a limitation to the present disclosure. Among them:

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

[0032] Figure 2 is the schematic diagram of the coal gasification black water circulation and black water waste heat recovery and utilization system of the present invention;

[0033] Among them, 1 is the syngas scrubber, 2 is the high-pressure flash tank, 3 is the low-pressure flash tank, 4 is the black water heat exchanger, 5 is the vacuum flash tank, 6 is the settling tank, 7 is the ash water tank, 8 is the low-pressure flash steam stripper, 9 is the high-pressure flash steam stripper, 10 is the vacuum flash condenser, 11 is the vacuum flash separation tank, 12 is the flash vacuum pump, 13 is the ash water pump, 14 is the deaerator water pump, 15 is the scrubber feed pump, and 16 is the low-pressure flash condenser. Detailed implementation manners

[0034] The following describes exemplary embodiments of the present disclosure with reference to the accompanying drawings. Various details of the embodiments of the present disclosure are included to assist understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0035] In a first aspect, the present invention provides a coal gasification black water circulation and black water waste heat recovery and utilization system, including a syngas scrubber 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 stripper 8, a high-pressure flash steam stripper 9, a vacuum flash condenser 10, a vacuum flash separation tank 11, and a flash vacuum pump 12; a medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubber 1. The upper end of the syngas scrubber 1 is connected to a syngas output pipeline, the lower end of the syngas scrubber 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 stripper 9, 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 stripper 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 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 separation tank 11, the lower end of the vacuum flash separation tank 11 is connected to the ash water tank 7, the upper end of the vacuum flash separation tank 11 is connected to the flash vacuum pump 12, the flash vacuum pump 12 is connected to two waste furnaces, and an air input pipeline is connected to the connection pipeline between the vacuum flash separation tank 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 clear 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 stripper 8, the upper end of the low-pressure flash steam stripper 8 is connected to the low-pressure flash condenser 16, the low-pressure flash condenser 16 is connected to a low-pressure flash steam output pipeline, the lower end of the low-pressure flash steam stripper 8 is connected to the high-pressure flash steam stripper 9, and the lower end of the high-pressure flash steam stripper 9 is connected to the syngas scrubber 1.

[0036] Among them, the shell-side inlet of the black water heat exchanger 4 is connected to the desalinated chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalinated chilled water return pipeline. Furthermore, the heat of the black water is exchanged and then supplied to the lithium bromide unit in the factory to produce chilled water for the production process. At the same time, the temperature of the black water is reduced, the operating load of the vacuum flashing system is reduced, the power consumption of the vacuum pump is saved, and the consumption of the circulating water system is saved. The black water heat exchanger 4 of the present invention is a shell-and-tube heat exchanger, which can continuously and efficiently exchange heat well. The vacuum flashing condenser 10 is respectively connected to the cooling water inlet pipeline and the cooling water outlet pipeline for heat exchange. The low-pressure flashing condenser 16 is respectively connected to the cooling water inlet pipeline and the cooling water outlet pipeline for heat exchange. A gray water pump 13 is provided between the gray water tank 7 and the low-pressure flashing stripping tower 8, and a deaerating water pump 14 is provided between the low-pressure flashing stripping tower 8 and the high-pressure flashing stripping tower 9. A stripping feed pump 15 is provided between the high-pressure flashing stripping tower 9 and the syngas scrubbing tower 1.

[0037] In a second aspect, the present invention provides a method for gasification black water circulation and black water waste heat recovery and utilization by using the above gasification black water circulation and black water waste heat recovery and utilization system, including the following steps:

[0038] (S1) Medium-pressure boiler water and syngas from the previous section are input into the syngas scrubbing tower 1. After washing, the syngas at the upper end of the syngas scrubbing tower 1 is output to go to conversion, and the high-temperature black water is output at the lower end of the syngas scrubbing tower 1;

[0039] (S2) The high-temperature black water enters the high-pressure flashing tank (0.5 Mpa) 2 for preliminary gas-liquid separation, separating out high-pressure flashing steam (0.5 Mpa, 158 °C) and high-temperature black water (0.5 Mpa, 158 °C). Among them, the high-pressure flashing steam is transported through a pipeline to the high-pressure flashing stripping tower 9;

[0040] (S3) The high-temperature black water is transported through a pipeline to the low-pressure flashing tank (0.15 Mpa, 130 °C) 3 for secondary gas-liquid separation, further separating out the volatile components in the liquid to form low-pressure flashing steam (0.15 Mpa, 130 °C) and high-temperature black water (0.15 Mpa, 130 °C). Among them, the low-pressure flashing steam is transported through a pipeline to the low-pressure flashing stripping tower 8;

[0041] (S4) The high-temperature black water (130 °C, 0.4 MPa) enters the tube side of the black water heat exchanger 4 and exchanges heat with the desalinated chilled water in the shell side of the black water heat exchanger 4, and the black water is greatly cooled down (83 °C, 0.4 MPa);

[0042] (S5) The black water after significant temperature reduction is transported through a pipeline to the vacuum flash tank (-0.05 Mpa, 83 °C) 5, and further gas-liquid separation is carried out by means of pressure reduction to further separate the volatile components in the liquid to form vacuum flash steam (-0.05 Mpa, 83 °C) and black water (-0.05 Mpa, 83 °C). Among them, the black water is transported through a pipeline to the settling tank 6, and the upper clarified liquid in the settling tank 6 overflows from the overflow outlet of the upper clarified liquid in the settling tank 6 and enters the ash water tank (atmospheric pressure, 80 °C) 7;

[0043] (S6) The ash water (atmospheric pressure, 80 °C) is transported through a pipeline to the low-pressure flash steam stripping tower (atmospheric pressure, 100 °C) 8, and further flash separation is carried out to improve the gas recovery efficiency and purify the ash water, separating out low-pressure flash steam (atmospheric pressure, 100 °C) and ash water (atmospheric pressure, 100 °C);

[0044] (S7) Subsequently, the ash water (atmospheric pressure, 100 °C) is transported through a pipeline to the high-pressure flash steam stripping tower (0.5 Mpa, 150 °C) 9 for deep purification and separation, separating out 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 a pipeline to the syngas scrubbing tower 1 for recycling and used for syngas scrubbing.

[0045] Before studying the coal gasification black water circulation and black water waste heat recovery and utilization system, through on-site sampling, the detection results of black water and scaling solids are as follows:

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

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

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

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

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

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

[0052]

[0053]

[0054] (5) The chemical composition of the solids in the black water is shown in Table 2:

[0055] Table 2 Chemical composition of the solids in the black water

[0056] Chemical composition Mass fraction / % Chemical composition Mass fraction / % <![CDATA[SiO2]]> 44.4400 ZnO 0.0372 <![CDATA[Al2O3]]> 15.2600 <![CDATA[V2O5]]> 0.0328 CaO 9.4500 <![CDATA[ZrO2]]> 0.0275 <![CDATA[Fe2O3]]> 5.7200 Cl 0.0273 <![CDATA[K2O]]> 1.4800 <![CDATA[Cr2O3]]> 0.0224 <![CDATA[P2O5]]> 1.2300 NiO 0.0136 <![CDATA[TiO2]]> 1.1800 PbO 0.0130 MgO 1.0700 <![CDATA[Ga2O3]]> 0.0130 <![CDATA[Na2O]]> 0.6100 <![CDATA[La2O3]]> 0.0089 S 0.2190 CuO 0.0079 SrO 0.1420 <![CDATA[Rb2O]]> 0.0035 MnO 0.1170

[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] According to the above test data of black water, a gasification black water circulation and black water waste heat recovery and utilization system for Embodiments 1-4 is constructed. Cut-off valves can be set at the front end or the end of the pipeline between each device in the system to cope with emergencies in industrial production. Details are not described herein again, and those skilled in the art can set cut-off valves at reasonable positions according to experience.

[0059] Embodiment 1

[0060] A gasification black water circulation and black water waste heat recovery and utilization system, see Figure 2 , 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 stripping tower 8, a high-pressure flash steam stripping tower 9, a vacuum flash condenser 10, a vacuum flash separation tank 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 a 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 stripping tower 9, 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 stripping tower 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 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 separation tank 11, the lower end of the vacuum flash separation tank 11 is connected to the ash water tank 7, the upper end of the vacuum flash separation tank 11 is connected to the flash vacuum pump 12, the flash vacuum pump 12 is connected to a two-stage gasifier, and an air input pipeline is connected to the connection pipeline between the vacuum flash separation tank 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 stripping tower 8, the upper end of the low-pressure flash steam stripping tower 8 is connected to a low-pressure flash condenser 16, and the low-pressure flash condenser 16 is connected to a low-pressure flash steam output pipeline. The lower end of the low-pressure flash steam stripping tower 8 is connected to the high-pressure flash steam stripping tower 9, and the lower end of the high-pressure flash steam stripping tower 9 is connected to the syngas scrubbing tower 1.

[0061] Among them, the shell-side inlet of the black water heat exchanger 4 is connected to the desalinated chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalinated chilled water return pipeline. The vacuum flash condenser 10 is respectively connected to the cooling water inlet pipeline and the cooling water outlet pipeline for heat exchange. The low-pressure flash condenser 16 is respectively connected to the cooling water inlet pipeline and the cooling water outlet pipeline for heat exchange. A ash water pump 13 is provided between the ash water tank 7 and the low-pressure flash steam stripping tower 8. A deaerating water pump 14 is provided between the low-pressure flash steam stripping tower 8 and the high-pressure flash steam stripping tower 9. A washing tower feed pump 15 is provided between the high-pressure flash steam stripping tower 9 and the syngas scrubbing tower 1.

[0062] Example 2

[0063] A coal gasification black water circulation and black water waste heat recovery and utilization 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 stripping tower 8 and a high-pressure flash steam stripping tower 9; 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 a 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 stripping tower 9, 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 stripping tower 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 stripping tower 8, the lower end of the low-pressure flash steam stripping tower 8 is connected to the high-pressure flash steam stripping tower 9, and the lower end of the high-pressure flash steam stripping tower 9 is connected to the syngas scrubbing tower 1. Among them, the shell-side inlet of the black water heat exchanger 4 is connected to the desalinated chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to the desalinated chilled water return pipeline.

[0064] Example 3

[0065] A coal gasification black water circulation and black water waste heat recovery and utilization system, including a syngas scrubber 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 stripping tower 8, a high-pressure flash steam stripping tower 9, a vacuum flash condenser 10, a vacuum flash separation tank 11 and a flash vacuum pump 12; a medium-pressure boiler water pipeline and a syngas pipeline are respectively connected to the syngas scrubber 1, the upper end of the syngas scrubber 1 is connected to a syngas output pipeline, the lower end of the syngas scrubber 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 stripping tower 9, 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 stripping tower 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 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 separation tank 11, the lower end of the vacuum flash separation tank 11 is connected to the ash water tank 7, the upper end of the vacuum flash separation tank 11 is connected to the flash vacuum pump 12, the flash vacuum pump 12 is connected to two waste furnaces, and an air input pipeline is connected to the connecting pipeline between the vacuum flash separation tank 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 stripping tower 8, the lower end of the low-pressure flash steam stripping tower 8 is connected to the high-pressure flash steam stripping tower 9, and the lower end of the high-pressure flash steam stripping tower 9 is connected to the syngas scrubber 1. Among them, the shell side inlet of the black water heat exchanger 4 is connected to a desalted chilled water supply pipeline, and the shell side outlet of the black water heat exchanger 4 is connected to a desalted chilled water return pipeline. The vacuum flash condenser 10 is respectively connected to a cooling water inlet pipeline and a cooling water outlet pipeline for heat exchange.

[0066] Example 4

[0067] A coal gasification black water circulation and black water waste heat recovery and utilization 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, a grey water tank 7, a low-pressure flash steam stripping tower 8, a high-pressure flash steam stripping tower 9, a vacuum flash condenser 10, a vacuum flash separation tank 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 a 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 stripping tower 9. 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 stripping tower 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 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 separation tank 11. The lower end of the vacuum flash separation tank 11 is connected to the grey water tank 7. The upper end of the vacuum flash separation tank 11 is connected to the flash vacuum pump 12. The flash vacuum pump 12 is connected to two waste furnaces. An air input pipeline is connected to the connection pipeline between the vacuum flash separation tank 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 clear liquid overflow outlet of the settling tank 6 is connected to the grey water tank 7. The grey water tank 7 is connected to the low-pressure flash steam stripping tower 8. The lower end of the low-pressure flash steam stripping tower 8 is connected to the high-pressure flash steam stripping tower 9. The lower end of the high-pressure flash steam stripping tower 9 is connected to the syngas scrubbing tower 1. Among them, the shell-side inlet of the black water heat exchanger 4 is connected to a desalted chilled water supply pipeline, and the shell-side outlet of the black water heat exchanger 4 is connected to a desalted chilled water return pipeline. The vacuum flash condenser 10 is respectively connected to a cooling water inlet pipeline and a cooling water outlet pipeline for heat exchange. A grey water pump 13 is arranged between the grey water tank 7 and the low-pressure flash steam stripping tower 8. An oxygen removal water pump 14 is arranged between the low-pressure flash steam stripping tower 8 and the high-pressure flash steam stripping tower 9. A scrubbing tower feed pump 15 is arranged between the high-pressure flash steam stripping tower 9 and the syngas scrubbing tower 1.

[0068] Example 5

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

[0070] (S1) Input medium-pressure boiler water and syngas from the previous section into the syngas scrubbing tower 1. After washing, the syngas output from the upper end of the syngas scrubbing tower 1 goes to shift, and the high-temperature black water is output from the lower end of the syngas scrubbing tower 1.

[0071] (S2) The high-temperature black water enters the high-pressure flash tank (0.5 Mpa) 2 and undergoes preliminary gas-liquid separation, separating out high-pressure flash steam (0.5 Mpa, 158 °C) and high-temperature black water (0.5 Mpa, 158 °C). Among them, the high-pressure flash steam is transported through a pipeline to the high-pressure flash steam stripper 9;

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

[0073] (S4) The high-temperature black water (130 °C, 0.4 MPa) enters the tube side of the black water heat exchanger 4 through a pipeline and exchanges heat with the desalted chilled water in the shell side of the black water heat exchanger 4. After that, the black water is cooled significantly (83 °C, 0.4 MPa); among them, the temperature of the desalted chilled water is about 70 °C, and the pressure is 0.4 - 0.5 MPa.

[0074] (S5) The significantly cooled black water is transported through a pipeline to the vacuum flash tank (-0.05 Mpa, 83 °C) 5, and further gas-liquid separation is carried out by means of pressure reduction, further separating out the volatile components in the liquid to form vacuum flash steam (-0.05 Mpa, 83 °C) and black water (-0.05 Mpa, 83 °C).

[0075] Among them, after the vacuum flash steam (-0.05 Mpa, 83 °C) is condensed by the vacuum flash condenser 10, the water vapor and low-boiling organic gases are transformed into liquid (-0.05 Mpa, 25 °C). Subsequently, it enters the vacuum flash separation tank 11. After further separation by the vacuum flash separation tank 11, vacuum flash steam (-0.05 Mpa, 25 °C) and a small amount of water (-0.05 Mpa, 25 °C) are separated out. The small amount of water enters the ash water tank (atmospheric pressure, 80 °C); the vacuum flash steam (-0.05 Mpa, 25 °C) is mixed with air and then transported to the two-waste furnace for utilization through the flash vacuum pump 12.

[0076] The black water is transported through a pipeline to the sedimentation tank 6. The upper clarified liquid of the sedimentation tank 6 overflows from the upper clarified liquid overflow outlet of the sedimentation tank 6 and enters the ash water tank (atmospheric pressure, 80 °C) 7;

[0077] (S6) The ash water (atmospheric pressure, 80 °C) is transported through a pipeline to the low-pressure flash steam stripper (atmospheric pressure, 100 °C) 8 for further flash separation to improve the gas recovery efficiency and purify the ash water, separating out low-pressure flash steam (atmospheric pressure, 100 °C) and ash water (atmospheric pressure, 100 °C);

[0078] (S7) Subsequently, the grey water (at atmospheric pressure, 100 °C) is transported through a pipeline to the high-pressure flash steam stripping tower (0.5 Mpa, 150 °C) 9 for deep purification and separation, separating out 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 a pipeline to the synthesis gas scrubbing tower 1 for recycling and used for synthesis gas scrubbing.

[0079] The coal gasification black water circulation and black water waste heat recovery and utilization system of the present invention undergoes multi-stage enterprise separation and purification to finally obtain purified water that meets the requirements. At the same time, a black water heat exchanger is set up in the system, and desalted chilled water is used as the heat transfer medium to extract the heat of the black water, supply the heat to the lithium bromide unit in the factory to produce chilled water for the production process, and at the same time achieve the purpose of cooling the black water, reduce the operating load of the vacuum flash evaporation system, save the power consumption of the vacuum pump, and save the consumption of the circulating water system. The coal gasification black water circulation and black water waste heat recovery and utilization system of the present invention has a simple structure and ingenious concept, and is more suitable for popularization and application. The method of coal gasification black water circulation and black water waste heat recovery and utilization of the present invention is simple, easy to implement, efficient, and low-cost. After being treated by the coal gasification black water circulation and black water waste heat recovery and utilization system of the present invention, the coal gasification black water can be reused as the circulating water for the synthesis gas scrubbing tower, realizing the recycling of water resources, reducing the intake of fresh water and the discharge of wastewater, reducing production costs and environmental pressure; at the same time, solving the problem of scale and blockage of the black water pipeline caused by high temperature, and being able to fully displace the waste heat of the black water for effective utilization, reducing carbon and saving energy, and at the same time achieving the purpose of cooling the black water, saving the cooling cost of the vacuum flash evaporation system, and creating continuous and reliable economic benefits for the enterprise.

[0080] It should be understood that the above-mentioned coal gasification black water circulation and black water waste heat recovery and utilization system and method can be reordered, steps can be added or deleted. As long as the desired results of the technical solutions disclosed in this disclosure can be achieved, the present invention is not limited herein.

[0081] The above specific embodiments do not constitute a limitation to the protection scope of the present invention disclosure. 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 the present invention disclosure shall be included within the protection scope of the present invention disclosure.

Claims

1. A coal gasification black water circulation and black water waste heat recovery system, characterized in that: The invention comprises a synthesis gas washing 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 stripping tower (8) and a high-pressure flash steam stripping tower (9); a medium-pressure boiler water pipeline and a synthesis gas pipeline are respectively connected to the synthesis gas washing tower (1); the upper end of the synthesis gas washing tower (1) is connected to the synthesis gas output pipeline; the lower end of the synthesis gas washing 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 stripping tower (9); 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 stripping tower (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 sedimentation tank (6), the upper clarified liquid overflow port of the sedimentation tank (6) is connected to the gray water tank (7), the gray water tank (7) is connected to the low-pressure flash steam stripping tower (8), the lower end of the low-pressure flash steam stripping tower (8) is connected to the high-pressure flash steam stripping tower (9), and the lower end of the high-pressure flash steam stripping tower (9) is connected to the synthesis gas washing tower (1).

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

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

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

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

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

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

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

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

10. A method for circulating coal gasification black water and recovering black water waste heat using the coal gasification black water circulation and black water waste heat recovery system according to any one of claims 1 to 9, characterized in that: The steps include: (S1) medium-pressure boiler water and synthesis gas from the previous stage are input into the synthesis gas washing tower (1). After washing, the synthesis gas is output from the upper end of the synthesis gas washing tower (1) for conversion, and the lower end of the synthesis gas washing tower (1) outputs high-temperature black water; (S2) After the high-temperature black water enters the high-pressure flash tank (2), a preliminary gas-liquid separation is performed to separate high-pressure flash steam and high-temperature black water, wherein the high-pressure flash steam is transported to the high-pressure flash steam stripping tower (9) via a pipeline; (S3) the high-temperature black water is transported to the low-pressure flash tank (3) through a pipeline for secondary gas-liquid separation, and the volatile components in the liquid are further separated to form low-pressure flash steam and high-temperature black water, wherein the low-pressure flash steam is transported to the low-pressure flash steam stripping tower (8) through a pipeline; (S4) The high-temperature black water is transported to the tube side of the black water heat exchanger (4) through a pipeline, and after heat exchange with the desalinated chilled water in the shell side of the black water heat exchanger (4), the black water is greatly cooled; (S5) the black water after being greatly cooled is transported to the vacuum flash tank (5) via a pipeline, and further gas-liquid separation is performed by decompression, and the volatile components in the liquid are further separated to form vacuum flash steam and black water, wherein the black water is transported to the sedimentation tank (6) via a pipeline, and the upper clarified liquid of the sedimentation tank (6) overflows from the upper clarified liquid overflow port of the sedimentation tank (6) into the gray water tank (7); (S6) the grey water is transported to the low-pressure flash steam stripping tower (8) via a pipeline, and further flash steam separation is performed to improve gas recovery efficiency and purify the grey water, thereby separating the low-pressure flash steam and grey water; (S7) The grey water is then transported via a pipeline to the high-pressure flash steam stripping tower (9) for deep purification and separation to separate purified water and high-pressure flash steam. The high-pressure flash steam is transported to the deconversion stripping tower, and the purified water is transported via a pipeline to the synthesis gas washing tower (1) for recycling and use in synthesis gas washing.

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