Coal chemical industry gasification black water energy recovery system and method

Abstract

The invention provides a coal chemical industry gasified black water energy recovery system which comprises a high-pressure flash tank, a black water liquid expansion machine, a vacuum flash tank, a vacuum flash condenser, an extractor and a hot water tower, and the high-pressure flash tank is provided with a gasified black water inlet, a high-temperature steam outlet and a low-temperature black water outlet. The black water liquid expansion machine is provided with a low-temperature black water inlet, a superheated steam outlet and a normal-pressure saturated black water outlet, the vacuum flash tank is provided with a normal-pressure saturated black water inlet, a low-temperature steam outlet and a saturated liquid black water outlet, and the vacuum flash condenser is provided with a low-temperature steam inlet, an uncondensed gas outlet and a condensed water outlet. The extractor is provided with a high-temperature steam inlet, a mixed steam inlet and a steam-water mixture outlet, and the hot water tower is provided with a steam-water mixture inlet, a fresh water inlet, a conversion condensate inlet, a hot water outlet and a grey water outlet. The energy recovery efficiency is greatly improved, the performance of the vacuum system is optimized, the black water concentration effect is improved, and efficient circulation of water resources and full recovery of black water energy are achieved.

Description

Technical Field

[0001] The invention relates to a coal chemical waste heat recovery and utilization system, and in particular to a coal chemical gasification black water energy recovery system and method, belonging to the technical field of coal chemical waste heat recovery. Background Art

[0002] As one of the important energy and chemical industries in my country, the coal chemical industry occupies an important position in the national economy. Among them, the coal gasification process is the core link of the coal chemical industry, which is usually operated by a water-coal slurry gasifier or a pulverized coal gasifier. During the cooling and washing process of coal gasification, a large amount of high-temperature gasification washing water, commonly known as "gasification black water", will be produced. This black water usually has a temperature between 230-260°C and contains a large amount of heat energy. According to the process requirements, the gasification black water needs to be cooled to below 60°C for clarification and reuse. Therefore, how to effectively reduce the temperature of black water and recover the heat energy in it at the same time has become an important technical challenge facing the coal chemical industry.

[0003] At present, the blackwater energy recovery system commonly used in the industry mainly includes high-pressure, low-pressure, and vacuum three-stage flash evaporation cooling, as well as the process flow of heat exchange cooling in the final heat exchanger. Specifically, high-pressure and low-pressure flash evaporation can reduce the blackwater temperature to about 130°C, while recovering part of the heat of the flashed low-pressure steam. However, in the process of further cooling the blackwater from 130°C to 60°C, it mainly relies on cooling water for heat exchange, and this part of the heat is often not effectively recycled. The energy utilization efficiency of the blackwater energy recovery system using this traditional cooling method is reduced, and a large amount of low-grade heat energy generated by cooling from 130°C to 60°C is directly discharged into the environment, resulting in energy waste. In addition, due to the use of a large amount of cooling water, it not only increases water resource consumption, but also may cause thermal pollution. Summary of the invention

[0004] Based on the above background, the purpose of the present invention is to provide a coal chemical gasification black water energy recovery system and method, which has an optimized black water energy recovery process flow, fully recovers and utilizes the energy of the high temperature and high pressure section and the low temperature and low pressure section of the coal chemical gasification black water, and improves the black water energy recovery efficiency.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A coal chemical gasification black water energy recovery system, comprising a high-pressure flash tank, a black water liquid expander, a vacuum flash tank, a vacuum flash condenser, an extractor and a hot water tower, wherein the high-pressure flash tank is provided with a gasified black water inlet, a high-temperature steam outlet and a low-temperature black water outlet, the black water liquid expander is provided with a low-temperature black water inlet, a superheated steam outlet and a normal-pressure saturated black water outlet, the vacuum flash tank is provided with a normal-pressure saturated black water inlet, a low-temperature steam outlet and a saturated liquid black water outlet, the vacuum flash condenser is provided with a low-temperature steam inlet, an uncondensed gas outlet and a condensed water outlet, the extractor is provided with a high-temperature steam inlet, a mixed steam inlet and a steam-water mixture outlet, and the hot water tower is provided with a steam-water mixture inlet, a fresh water inlet, a conversion condensate inlet, a hot water outlet and a gray water outlet;

[0007] The vaporized black water inlet of the high-pressure flash tank is used to input vaporized black water, the high-temperature steam outlet of the high-pressure flash tank is connected to the high-temperature steam inlet of the extractor through a pipeline, and the low-temperature black water outlet of the high-pressure flash tank is connected to the low-temperature black water inlet of the black water liquid expander through a pipeline;

[0008] The superheated steam outlet of the black water liquid expander is connected to the uncondensed gas outlet of the vacuum flash condenser through a pipeline and then connected to the mixed steam inlet of the extractor. The normal pressure saturated black water outlet of the black water liquid expander is connected to the normal pressure saturated black water inlet of the vacuum flash tank through a pipeline.

[0009] The low-temperature steam outlet of the vacuum flash tank is connected to the low-temperature steam inlet of the vacuum flash condenser through a pipeline, and the liquid black water outlet of the vacuum flash tank is used to discharge the liquid black water;

[0010] The uncondensed gas outlet of the vacuum flash condenser is connected to the mixed steam inlet of the extractor through a pipeline, and the condensed water outlet of the vacuum flash condenser is used to discharge the condensed gray water;

[0011] The steam-water mixture outlet of the extractor is connected to the steam-water mixture inlet of the hot water tower through a pipeline. The fresh water inlet of the hot water tower is used to input fresh cold water, the conversion condensate inlet of the hot water tower is used to input conversion condensate, the hot water outlet of the hot water tower is used to output hot water, and the gray water outlet of the hot water tower is used to discharge gray water.

[0012] Preferably, the black water liquid expander is provided with a speed regulating valve for speeding up the low-temperature black water inlet medium.

[0013] Preferably, the black water liquid expander is a gas-liquid two-phase expander.

[0014] Preferably, a first regulating valve is provided on the pipeline between the low-temperature black water outlet of the high-pressure flash tank and the low-temperature black water inlet of the black water liquid expander, a second regulating valve is provided on the pipeline between the high-temperature steam outlet of the high-pressure flash tank and the high-temperature steam inlet of the extractor, a third regulating valve is provided on the pipeline at the superheated steam outlet of the black water liquid expander, and a fourth regulating valve is provided on the pipeline at the mixed steam inlet of the extractor.

[0015] Preferably, the coal chemical gasification black water energy recovery system also includes an ash water tank, a sedimentation tank and a vacuum belt filter which are connected in sequence, the condensate outlet of the vacuum flash condenser is connected to the ash water tank through a pipeline, and the saturated liquid black water outlet of the vacuum flash tank is connected to the sedimentation tank through a pipeline.

[0016] A method for recovering black water energy from coal chemical industry gasification using the above-mentioned coal chemical industry gasification black water energy recovery system comprises the following steps:

[0017] The vaporized black water with a temperature of 230-260°C and a pressure of 5.5-6.5MPa is transported to a high-pressure flash tank for high-pressure flash separation, and high-temperature steam with a temperature of 150-180°C and a pressure of 0.5-0.8MPa and low-temperature black water with a temperature of 150-170°C and a pressure of 0.5-0.6MPa are output;

[0018] The low-temperature black water is transported to the black water liquid expander for expansion and power generation, and the expanded normal pressure saturated black water with a temperature of 35-45°C is transported to the vacuum flash tank for vacuum flash evaporation;

[0019] The low-temperature steam generated by the vacuum flash tank is transported to the vacuum flash condenser for condensation, the condensed water is discharged, the uncondensed gas is mixed with the superheated steam generated by the expansion of the black water liquid expander and input into the extractor, and the high-temperature steam of the high-pressure flash tank is input into the extractor, so that the three steam / gases of different qualities are mixed, and the negative pressure in the vacuum flash tank is maintained at -80kPa through the cooperation of the extractor and the vacuum flash condenser;

[0020] The steam-water mixture from the extractor is transported to the hot water tower, fresh water with a temperature of 15-25°C is added to the upper part of the hot water tower, and conversion condensate with a temperature of 40-60°C is added to the middle part of the hot water tower. The hot water output from the top of the hot water tower is transported to the subsequent process section, and the gray water at the bottom of the hot water tower is discharged.

[0021] Preferably, the coal chemical gasification black water energy recovery system further comprises an ash water tank, a sedimentation tank and a vacuum belt filter, and the coal chemical gasification black water energy recovery method further comprises the following steps:

[0022] The condensed water from the vacuum flash condenser is transported to the gray water tank, the gray water in the gray water tank is transported to the sedimentation tank, the saturated liquid black water from the vacuum flash tank is transported to the sedimentation tank to mix with the gray water for sedimentation, and the high-concentration liquid precipitated in the sedimentation tank is transported to the vacuum belt filter for filtration.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] A coal chemical gasification black water energy recovery system of the present invention, by introducing a black water liquid expander and optimizing the application of an extractor, fully utilizes the energy carried by black water, can generate an additional 80kW of electricity per hour, and deeply utilizes the high-temperature steam energy generated by the high-pressure flash tank to drive the extractor to reduce the pressure of the vacuum flash tank from the original -35kPa to -80kPa, saving 7kW of electricity per hour. The present invention not only greatly improves the energy recovery efficiency, but also optimizes the performance of the vacuum system, improves the black water concentration effect, and realizes the efficient circulation of water resources and the full recovery of black water energy through the close integration of equipment and the cascade utilization of thermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0026] Figure 1 It is a structural schematic diagram of a coal chemical gasification black water energy recovery system of the present invention;

[0027] In the figure: 1, high pressure flash tank; 2, black water liquid expander; 3, vacuum flash tank; 4, vacuum flash condenser; 5, extractor; 6, hot water tower; 7, gray water tank; 8, sedimentation tank; 9, vacuum belt filter; 10, first regulating valve; 11, second regulating valve; 12, third regulating valve; 13, fourth regulating valve; 101, gasified black water inlet; 102, high temperature steam outlet; 103, low temperature black water outlet; 201, low temperature black water inlet; 202, superheated steam outlet; 20 3. Normal pressure saturated black water outlet; 301. Normal pressure saturated black water inlet; 302. Low temperature steam outlet; 303. Saturated liquid black water outlet; 401. Low temperature steam inlet; 402. Uncondensed gas outlet; 403. Condensed water outlet; 501. High temperature steam inlet; 502. Mixed steam inlet; 503. Soda-water mixture outlet; 601. Soda-water mixture inlet; 602. Fresh water inlet; 603. Condensate inlet; 604. Hot water outlet; 605. Grey water outlet. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0029] In the present invention, unless otherwise specified, all parts and percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are universal standard parts or components known to those skilled in the art, and their structures and principles are known to those skilled in the art through technical manuals or conventional experimental methods.

[0030] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may also be implemented by those skilled in the art without these specific details.

[0031] The embodiment of the present invention discloses a coal chemical gasification black water energy recovery system, comprising a high-pressure flash tank 1, a black water liquid expander 2, a vacuum flash tank 3, a vacuum flash condenser 4, an extractor 5 and a hot water tower 6, wherein the high-pressure flash tank 1 is provided with a gasified black water inlet 101, a high-temperature steam outlet 102 and a low-temperature black water outlet 103, the black water liquid expander 2 is provided with a low-temperature black water inlet 201, a superheated steam outlet 202 and a normal pressure saturated black water outlet 203, the vacuum flash tank 3 is provided with a normal pressure saturated black water inlet 301, a low-temperature steam outlet 302 and a saturated liquid black water outlet 303, the vacuum flash condenser 4 is provided with a low-temperature steam inlet 401, an uncondensed gas outlet 402 and a condensed water outlet 403, the extractor 5 is provided with a high-temperature steam inlet 501, a mixed steam inlet 502 and a steam-water mixture outlet 503, and the hot water tower 6 is provided with a steam-water mixture inlet 601, a fresh water inlet 602, a conversion condensate inlet 603, a hot water outlet 604 and a gray water outlet 605.

[0032] The vaporized black water inlet 101 of the high-pressure flash tank 1 is used to input vaporized black water, the high-temperature steam outlet 102 of the high-pressure flash tank 1 is connected to the high-temperature steam inlet 501 of the extractor 5 through a pipeline, and the low-temperature black water outlet 103 of the high-pressure flash tank 1 is connected to the low-temperature black water inlet 201 of the black water liquid expander 2 through a pipeline.

[0033] The superheated steam outlet 202 of the black water liquid expander 2 is merged into the uncondensed gas outlet 402 of the vacuum flash condenser 4 through a pipeline and then connected to the mixed steam inlet 502 of the extractor 5. The normal pressure saturated black water outlet 203 of the black water liquid expander 2 is connected to the normal pressure saturated black water inlet 301 of the vacuum flash tank 3 through a pipeline.

[0034] The low-temperature steam outlet 302 of the vacuum flash tank 3 is connected to the low-temperature steam inlet 401 of the vacuum flash condenser 4 through a pipeline, and the liquid black water outlet of the vacuum flash tank 3 is used to discharge the liquid black water.

[0035] The uncondensed gas outlet 402 of the vacuum flash condenser 4 is connected to the mixed steam inlet 502 of the extractor 5 through a pipeline, and the condensed water outlet 403 of the vacuum flash condenser 4 is used to discharge condensed gray water.

[0036] The steam-water mixture outlet 503 of the extractor 5 is connected to the steam-water mixture inlet 601 of the hot water tower 6 through a pipeline. The fresh water inlet 602 of the hot water tower 6 is used to input fresh cold water, the conversion condensate inlet 603 of the hot water tower 6 is used to input conversion condensate, the hot water outlet 604 of the hot water tower 6 is used to output hot water, and the gray water outlet 605 of the hot water tower 6 is used to discharge gray water.

[0037] By introducing the black water liquid expander 2 and optimizing the application of the extractor 5, compared with the traditional process of directly reducing the pressure and flashing the gasified black water and configuring a vacuum pump for the vacuum flash tank 3, the energy carried by the black water is fully utilized, and an additional 80 kW of electricity can be generated per hour. The high-temperature steam energy generated by the high-pressure flash tank 1 is fully utilized to drive the extractor 5 to reduce the pressure of the vacuum flash tank 3 from the original -35 kPa to -80 kPa, saving 7 kW of electricity per hour.

[0038] Specifically, the black water liquid expander 2 is provided with a speed regulating valve for speeding up the medium of the low temperature black water inlet 201. The speed regulating valve speeds up the medium by 20%. After speeding up, part of the low temperature black water medium will be gasified into low pressure steam to form a gas-liquid mixed medium.

[0039] Specifically, the blackwater liquid expander 2 is a gas-liquid two-phase expander. The gas-liquid mixed medium passes through the guide bend in the gas-liquid two-phase expander, and is separated into gas and liquid under the action of centrifugal force, and then enters the gas-liquid diversion nozzle by adjusting the seesaw, pushing the impeller to expand and work. The impeller can undertake the expansion work from the gas phase and the liquid phase. The specific internal structure of the gas-liquid two-phase expander is the existing technology and will not be repeated here.

[0040] Specifically, a first regulating valve 10 is provided on the pipeline between the low-temperature black water outlet 103 of the high-pressure flash tank 1 and the low-temperature black water inlet 201 of the black water liquid expander 2, a second regulating valve 11 is provided on the pipeline between the high-temperature steam outlet 102 of the high-pressure flash tank 1 and the high-temperature steam inlet 501 of the extractor 5, a third regulating valve 12 is provided on the pipeline at the superheated steam outlet 202 of the black water liquid expander 2, and a fourth regulating valve 13 is provided on the pipeline at the mixed steam inlet 502 of the extractor 5. The main function of the first regulating valve 10 is to control the flow rate of low-temperature black water entering the black water liquid expander 2, thereby adjusting the operating load and output power of the black water liquid expander 2, and assisting in maintaining the liquid level balance in the high-pressure flash tank 1. The main function of the second regulating valve 11 is to control the flow rate of high-temperature steam entering the extractor 5, thereby adjusting the extraction capacity of the extractor 5. The main function of the third regulating valve 12 is to control the flow rate of superheated steam discharged from the black water liquid expander 2, control the back pressure of the black water liquid expander 2, thereby affecting its expansion ratio and output power. The back pressure of the black water liquid expander 2 can withstand -80KPa, and the back temperature can reach about 110° C. The main function of the fourth regulating valve 13 is to control the mixed steam flow entering the extractor 5, thereby adjusting its extraction effect and vacuum degree.

[0041] Specifically, the coal chemical gasification black water energy recovery system further includes an ash water tank 7, a sedimentation tank 8 and a vacuum belt filter 9 which are connected in sequence, the condensed water outlet 403 of the vacuum flash condenser 4 is connected to the ash water tank 7 through a pipeline, and the saturated liquid black water outlet 303 of the vacuum flash tank 3 is connected to the sedimentation tank 8 through a pipeline. The ash water tank 7, the sedimentation tank 8 and the vacuum belt filter 9 cooperate to perform solid-liquid separation on the ash water.

[0042] A method for recovering black water energy from coal chemical industry gasification using the above-mentioned coal chemical industry gasification black water energy recovery system comprises the following steps:

[0043] The vaporized black water with a temperature of 230-260°C and a pressure of 5.5-6.5 MPa is transported to the high-pressure flash tank 1 for high-pressure flash separation, and high-temperature steam with a temperature of 150-180°C and a pressure of 0.5-0.8 MPa and low-temperature black water with a temperature of 150-170°C and a pressure of 0.5-0.6 MPa are output;

[0044] The low-temperature black water is transported to the black water liquid expander 2 for expansion and power generation, and the expanded normal pressure saturated black water with a temperature of 35-45°C is transported to the vacuum flash tank 3 for vacuum flash evaporation;

[0045] The low-temperature steam generated by the vacuum flash tank 3 is transported to the vacuum flash condenser 4 for condensation, and the condensed water is discharged. The uncondensed gas is mixed with the superheated steam generated by the expansion of the black water liquid expander 2 and input into the extractor 5, and the high-temperature steam of the high-pressure flash tank 1 is input into the extractor 5, so that the three steam / gases of different qualities are mixed, and the negative pressure in the vacuum flash tank 3 is maintained at -80kPa through the cooperation of the extractor 5 and the vacuum flash condenser 4;

[0046] The steam-water mixture from the extractor 5 is transported to the hot water tower 6, fresh water with a temperature of 15-25°C is added to the upper part of the hot water tower 6, and the conversion condensate with a temperature of 40-60°C is added to the middle part of the hot water tower 6. The hot water output from the top of the hot water tower 6 is transported to the subsequent stage, and the gray water at the bottom of the hot water tower 6 is discharged.

[0047] Specifically, the method for recovering black water energy from coal chemical gasification further includes the following steps:

[0048] The condensed water of the vacuum flash condenser 4 is transported to the gray water tank 7, the gray water in the gray water tank 7 is transported to the sedimentation tank 8, the saturated liquid black water of the vacuum flash tank 3 is transported to the sedimentation tank 8 to mix with the gray water for sedimentation, and the high-concentration liquid precipitated in the sedimentation tank 8 is transported to the vacuum belt filter 9 for filtration.

[0049] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A coal chemical gasification black water energy recovery system, characterized by: The coal chemical gasification black water energy recovery system comprises a high-pressure flash tank (1), a black water liquid expander (2), a vacuum flash tank (3), a vacuum flash condenser (4), an extractor (5) and a hot water tower (6), wherein the high-pressure flash tank (1) is provided with a gasified black water inlet (101), a high-temperature steam outlet (102) and a low-temperature black water outlet (103), the black water liquid expander (2) is provided with a low-temperature black water inlet (201), a superheated steam outlet (202) and a normal-pressure saturated black water outlet (203), the vacuum flash tank (3) is provided with a normal-pressure saturated black water inlet (3 01), a low-temperature steam outlet (302) and a saturated liquid black water outlet (303), the vacuum flash condenser (4) is provided with a low-temperature steam inlet (401), an uncondensed gas outlet (402) and a condensed water outlet (403), the extractor (5) is provided with a high-temperature steam inlet (501), a mixed steam inlet (502) and a steam-water mixture outlet (503), the hot water tower (6) is provided with a steam-water mixture inlet (601), a fresh water inlet (602), a conversion condensate inlet (603), a hot water outlet (604) and a gray water outlet (605); The vaporized black water inlet (101) of the high-pressure flash tank (1) is used to input vaporized black water, the high-temperature steam outlet (102) of the high-pressure flash tank (1) is connected to the high-temperature steam inlet (501) of the extractor (5) through a pipeline, and the low-temperature black water outlet (103) of the high-pressure flash tank (1) is connected to the low-temperature black water inlet (201) of the black water liquid expander (2) through a pipeline; The superheated steam outlet (202) of the black water liquid expander (2) is connected to the uncondensed gas outlet (402) of the vacuum flash condenser (4) through a pipeline and then connected to the mixed steam inlet (502) of the extractor (5); the normal pressure saturated black water outlet (203) of the black water liquid expander (2) is connected to the normal pressure saturated black water inlet (301) of the vacuum flash tank (3) through a pipeline; The low-temperature steam outlet (302) of the vacuum flash tank (3) is connected to the low-temperature steam inlet (401) of the vacuum flash condenser (4) through a pipeline, and the liquid black water outlet of the vacuum flash tank (3) is used to discharge the liquid black water; The uncondensed gas outlet (402) of the vacuum flash condenser (4) is connected to the mixed steam inlet (502) of the extractor (5) through a pipeline, and the condensed water outlet (403) of the vacuum flash condenser (4) is used to discharge condensed gray water; The steam-water mixture outlet (503) of the extractor (5) is connected to the steam-water mixture inlet (601) of the hot water tower (6) through a pipeline. The fresh water inlet (602) of the hot water tower (6) is used to input fresh cold water, the conversion condensate inlet (603) of the hot water tower (6) is used to input conversion condensate, the hot water outlet (604) of the hot water tower (6) is used to output hot water, and the gray water outlet (605) of the hot water tower (6) is used to discharge gray water.

2. A coal chemical gasification black water energy recovery system according to claim 1, characterized in that: The black water liquid expander (2) is provided with a speed regulating valve for increasing the speed of the low-temperature black water inlet (201) medium.

3. The coal chemical gasification black water energy recovery system according to claim 1, characterized in that: The black water liquid expander (2) is a gas-liquid two-phase expander.

4. The coal chemical gasification black water energy recovery system according to claim 1, characterized in that: A first regulating valve (10) is provided on the pipeline between the low-temperature black water outlet (103) of the high-pressure flash tank (1) and the low-temperature black water inlet (201) of the black water liquid expander (2), a second regulating valve (11) is provided on the pipeline between the high-temperature steam outlet (102) of the high-pressure flash tank (1) and the high-temperature steam inlet (501) of the extractor (5), a third regulating valve (12) is provided on the pipeline at the superheated steam outlet (202) of the black water liquid expander (2), and a fourth regulating valve (13) is provided on the pipeline at the mixed steam inlet (502) of the extractor (5).

5. The coal chemical gasification black water energy recovery system according to claim 1, characterized in that: The coal chemical gasification black water energy recovery system also includes an ash water tank (7), a sedimentation tank (8) and a vacuum belt filter (9) which are connected in sequence; the condensate outlet (403) of the vacuum flash condenser (4) is connected to the ash water tank (7) through a pipeline, and the saturated liquid black water outlet (303) of the vacuum flash tank (3) is connected to the sedimentation tank (8) through a pipeline.

6. A method for recovering energy from coal chemical gasification black water using the coal chemical gasification black water energy recovery system as described in any one of claims 1 to 5, characterized in that: The method comprises the following steps: The vaporized black water at a temperature of 230-260° C. and a pressure of 5.5-6.5 MPa is transported to a high-pressure flash tank (1) for high-pressure flash separation, and high-temperature steam at a temperature of 150-180° C. and a pressure of 0.5-0.8 MPa and low-temperature black water at a temperature of 150-170° C. and a pressure of 0.5-0.6 MPa are output; The low-temperature black water is transported to a black water liquid expander (2) for expansion to generate electricity, and the expanded normal-pressure saturated black water at a temperature of 35 to 45° C. is transported to a vacuum flash tank (3) for vacuum flash evaporation; The low-temperature steam generated by the vacuum flash tank (3) is transported to the vacuum flash condenser (4) for condensation, and the condensed water is discharged. The uncondensed gas is mixed with the superheated steam generated by the expansion of the black water liquid expander (2) and input into the extractor (5), and the high-temperature steam of the high-pressure flash tank (1) is input into the extractor (5) to mix the steam / gas of three different qualities. Through the cooperation of the extractor (5) and the vacuum flash condenser (4), the negative pressure in the vacuum flash tank (3) is maintained at -80 kPa; The steam-water mixture from the extractor (5) is transported to the hot water tower (6), fresh water with a temperature of 15 to 25°C is added to the upper part of the hot water tower (6), and conversion condensate with a temperature of 40 to 60°C is added to the middle part of the hot water tower (6). The hot water output from the top of the hot water tower (6) is transported to the subsequent process section, and the gray water at the bottom of the hot water tower (6) is discharged.

7. A method for recovering energy from coal chemical gasification black water according to claim 6, characterized in that: The coal chemical industry gasification black water energy recovery system further comprises an ash water tank (7), a sedimentation tank (8) and a vacuum belt filter (9), and the coal chemical industry gasification black water energy recovery method further comprises the following steps: The condensed water from the vacuum flash condenser (4) is transported to the gray water tank (7), the gray water from the gray water tank (7) is transported to the sedimentation tank (8), the saturated liquid black water from the vacuum flash tank (3) is transported to the sedimentation tank (8) to be mixed with the gray water for sedimentation, and the high-concentration liquid precipitated in the sedimentation tank (8) is transported to the vacuum belt filter (9) for filtration.

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