Coal chemical gasification black water energy recovery system and method

Abstract

The present application provides a kind of coal chemical gasification black water energy recovery system, including high-pressure flash tank, black water liquid expander, vacuum flash tank, vacuum flash condenser, suction and hot water tower, high-pressure flash tank is equipped with gasification black water import, high-temperature steam outlet and low-temperature black water outlet, black water liquid expander is equipped with low-temperature black water import, superheated steam outlet and normal-pressure saturated black water outlet, vacuum flash tank is equipped with normal-pressure saturated black water import, low-temperature steam outlet and saturated liquid black water outlet, vacuum flash condenser is equipped with low-temperature steam inlet, uncondensed gas outlet and condensate outlet, suction is equipped with high-temperature steam inlet, mixed steam inlet and steam-water mixture outlet, hot water tower is equipped with steam-water mixture import, fresh water import, shift condensate import, hot water outlet and grey water outlet.The present application not only greatly improves energy recovery efficiency, but also optimizes vacuum system performance, improves black water concentration effect, realizes water resource efficient circulation and black water energy full recovery.

Description

TECHNICAL FIELD

[0001] The present application relates to a coal chemical waste heat recovery system, 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

[0002] Coal gasification process is the core link of coal chemical industry, usually using coal water slurry gasifier or pulverized coal gasifier for operation. In 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. The temperature of this black water is usually between 230-260℃, and it contains a large amount of heat energy. According to the process requirements, the gasification black water needs to be cooled to below 60℃ for clarification treatment 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 faced by the coal chemical industry.

[0003] At present, the commonly used black water energy recovery system in the industry mainly includes high-pressure, low-pressure, vacuum three-stage flash cooling, and final-stage heat exchanger heat exchange cooling process. Specifically, high-pressure and low-pressure flash cooling can reduce the temperature of black water to about 130℃, and recover part of the low-pressure steam heat flashed out. However, in the process of further cooling the black water from 130℃ to 60℃, the cooling water is mainly relied on for heat exchange, and this part of heat is often not effectively recovered and utilized. The energy utilization efficiency of the black water energy recovery system using this traditional cooling method is low, and a large amount of low-grade heat energy generated by cooling from 130℃ to 60℃ is directly discharged into the environment, resulting in energy waste, and because a large amount of cooling water is used, not only the water resource consumption is increased, but also the thermal pollution may be caused. SUMMARY

[0004] Based on the above background, the purpose of the present application is to provide a coal chemical gasification black water energy recovery system and method, which has an optimized black water energy recovery process, fully recovers and utilizes the energy of the high-temperature high-pressure section and the low-temperature 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 purpose of the application, the present application provides the following technical solutions:

[0006] The coal chemical gasification black water energy recovery system comprises a high-pressure flash tank, a black water liquid expander, a vacuum flash tank, a vacuum flash condenser, an ejector and a hot water tower, the high-pressure flash tank is provided with a gasification 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 an atmospheric saturated black water outlet, the vacuum flash tank is provided with an atmospheric 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 ejector 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 shift condensate inlet, a hot water outlet and a grey water outlet.

[0007] The gasification black water inlet of the high-pressure flash tank is used for inputting gasification black water, the high-temperature steam outlet of the high-pressure flash tank is connected to the high-temperature steam inlet of the ejector 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 mixed steam inlet of the ejector through a pipeline and after the uncondensed gas outlet of the vacuum flash condenser, and the atmospheric saturated black water outlet of the black water liquid expander is connected to the atmospheric 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 for discharging liquid black water.

[0010] The uncondensed gas outlet of the vacuum flash condenser is connected to the mixed steam inlet of the ejector through a pipeline, and the condensed water outlet of the vacuum flash condenser is used for discharging condensed grey water.

[0011] The steam-water mixture outlet of the ejector 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 for inputting fresh cold water, the shift condensate inlet of the hot water tower is used for inputting shift condensate, the hot water outlet of the hot water tower is used for outputting hot water, and the grey water outlet of the hot water tower is used for discharging grey water.

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

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

[0014] As preferred, a first regulating valve is arranged 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 arranged on the pipeline between the high-temperature steam outlet of the high-pressure flash tank and the high-temperature steam inlet of the ejector, a third regulating valve is arranged on the pipeline at the superheated steam outlet of the black water liquid expander, and a fourth regulating valve is arranged on the pipeline at the mixed steam inlet of the ejector.

[0015] As preferred, the coal chemical gasification black water energy recovery system further comprises a grey water tank, a settling tank and a vacuum belt filter which are sequentially connected, the condensate water outlet of the vacuum flash condenser is connected to the grey water tank through a pipeline, and the saturated liquid black water outlet of the vacuum flash tank is connected to the settling tank through a pipeline.

[0016] A method for recovering energy from coal chemical gasification black water by using the coal chemical gasification black water energy recovery system described above, the method comprising the following steps:

[0017] The gasification black water with a temperature of 230-260℃ and a pressure of 5.5-6.5MPa is sent to the high-pressure flash tank for high-pressure flash separation, and high-temperature steam with a temperature of 150-180℃ and a pressure of 0.5-0.8MPa and low-temperature black water with a temperature of 150-170℃ and a pressure of 0.5-0.6MPa are outputted;

[0018] The low-temperature black water is sent to the black water liquid expander for expansion and power generation, and the expanded black water with a temperature of 35-45℃ and a pressure of 0.1MPa is sent to the vacuum flash tank for vacuum flash;

[0019] The low-temperature steam generated by the vacuum flash tank is sent to the vacuum flash condenser for condensation, and the condensate water is discharged, the uncondensed gas is mixed with the superheated steam generated by the expansion of the black water liquid expander to be inputted into the ejector, and the high-temperature steam from the high-pressure flash tank is inputted into the ejector, so that three different quality steams / gases are mixed, and the negative pressure of-80kPa in the vacuum flash tank is maintained by the cooperation of the ejector and the vacuum flash condenser.

[0020] The steam-water mixture from the ejector is sent to the hot water tower, fresh water with a temperature of 15-25℃ is supplied to the upper part of the hot water tower, and shift condensate with a temperature of 40-60℃ is supplied to the middle part of the hot water tower, the hot water outputted from the top of the hot water tower is sent to the subsequent process, and the grey water from the bottom of the hot water tower is discharged.

[0021] As preferred, the coal chemical gasification black water energy recovery system further comprises a grey water tank, a settling tank and a vacuum belt filter, and the method for recovering energy from coal chemical gasification black water further comprises the following steps:

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

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

[0024] The coal chemical gasification black water energy recovery system of the present application, by introducing a black water liquid expander and optimizing the use of the ejector, compared with the traditional process of directly flash evaporation of the gasification black water under reduced pressure and the configuration of a vacuum pump for the vacuum flash tank, fully utilizes the energy carried by the black water, can generate an additional 80kW of electric energy per hour, deeply utilizes the high-temperature steam energy generated by the high-pressure flash tank to drive the ejector to reduce the pressure of the vacuum flash tank from the original-35kPa to-80kPa, and saves 7kW of electric energy per hour; the present application not only greatly improves the energy recovery efficiency, but also optimizes the performance of the vacuum system, improves the black water concentration effect, and through the close integration of the equipment and the step-by-step utilization of heat energy, realizes the efficient recycling of water resources and the full recovery of black water energy. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

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

[0027] In the figure: 1, high-pressure flash tank; 2, black water liquid expander; 3, vacuum flash tank; 4, vacuum flash condenser; 5, ejector; 6, hot water tower; 7, ash water tank; 8, settling tank; 9, vacuum belt filter; 10, first regulating valve; 11, second regulating valve; 12, third regulating valve; 13, fourth regulating valve; 101, gasification black water inlet; 102, high-temperature steam outlet; 103, low-temperature black water outlet; 201, low-temperature black water inlet; 202, superheated steam outlet; 203, atmospheric saturated black water outlet; 301, atmospheric 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, steam-water mixture outlet; 601, steam-water mixture inlet; 602, fresh water inlet; 603, shift condensate inlet; 604, hot water outlet; 605, ash water outlet. DETAILED DESCRIPTION

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

[0029] In the present application, all the parts and percentages are by weight, 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 examples are conventional methods in the art, unless otherwise specified. The components or equipment in the following examples are general standard components or components known to those skilled in the art, and their structure and principles can be known to those skilled in the art through technical manuals or through conventional experimental methods.

[0030] The embodiments of the present application will be described in detail below in conjunction with the drawings. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, one or more embodiments can be practiced without these specific details.

[0031] The embodiments of the present application disclose a coal chemical gasification black water energy recovery system, which comprises a high-pressure flash tank 1, a black water liquid expander 2, a vacuum flash tank 3, a vacuum flash condenser 4, an ejector 5 and a hot water tower 6. The high-pressure flash tank 1 is provided with a gasification 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 an atmospheric saturated black water outlet 203. The vacuum flash tank 3 is provided with an atmospheric 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 ejector 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 shift condensate inlet 603, a hot water outlet 604 and a grey water outlet 605.

[0032] The gasification black water inlet 101 of the high-pressure flash tank 1 is used for inputting gasification 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 ejector 5 through a pipeline. 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 connected by a pipeline to the mixed steam inlet 502 of the ejector 5 after the non-condensed gas outlet 402 of the vacuum flash condenser 4, and the atmospheric saturated black water outlet 203 of the black water liquid expander 2 is connected by a pipeline to the atmospheric saturated black water inlet 301 of the vacuum flash tank 3.

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

[0035] The non-condensed gas outlet 402 of the vacuum flash condenser 4 is connected by a pipeline to the mixed steam inlet 502 of the ejector 5, and the condensed water outlet 403 of the vacuum flash condenser 4 is used to discharge condensed grey water.

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

[0037] By introducing the black water liquid expander 2 and optimizing the application of the ejector 5, the energy carried by the black water is fully utilized compared with the traditional process of directly flash decompressing the gasified black water and configuring a vacuum pump for the vacuum flash tank 3, 80kW of electric energy is additionally generated per hour, the high temperature steam energy generated by the high pressure flash tank 1 is deeply utilized, the pressure of the vacuum flash tank 3 is reduced from-35kPa to-80kPa by the ejector 5, and 7kW of electric energy is saved per hour.

[0038] Specifically, the black water liquid expander 2 is provided with a speed regulating valve for accelerating the medium of the low temperature black water inlet 201. The medium is accelerated by 20% through the speed regulating valve, and after acceleration, part of the low temperature black water medium is gasified into low pressure steam to form a gas-liquid mixed medium.

[0039] Specifically, the black water liquid expander 2 is a gas-liquid two-phase expander. The gas-liquid mixed medium passes through a guide elbow in the gas-liquid two-phase expander, is separated into gas and liquid under the action of centrifugal force, then passes through an adjusting flap, and then enters a gas-liquid split nozzle to push the impeller to expand and do work. The impeller can receive the expansion work from the gas phase and the liquid phase. The specific internal structure of the gas-liquid two-phase expander is prior art, which is not described here.

[0040] Specifically, a first regulating valve 10 is arranged 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 arranged 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 ejector 5, a third regulating valve 12 is arranged on the pipeline at the superheated steam outlet 202 of the black water liquid expander 2, and a fourth regulating valve 13 is arranged on the pipeline at the mixed steam inlet 502 of the ejector 5. The main function of the first regulating valve 10 is to control the flow of the low-temperature black water entering the black water liquid expander 2, so as to adjust the operating load and output power of the black water liquid expander 2 and assist 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 of the high-temperature steam entering the ejector 5, so as to adjust the pumping capacity of the ejector 5. The main function of the third regulating valve 12 is to control the flow of the superheated steam discharged from the black water liquid expander 2, so as to control the back pressure of the black water liquid expander 2 and thus affect the expansion ratio and output power thereof. The back pressure after the black water liquid expander 2 can be-80 KPa, and the temperature after the black water liquid expander 2 can reach about 110℃. The main function of the fourth regulating valve 13 is to control the flow of the mixed steam entering the ejector 5, so as to adjust the pumping effect and vacuum degree of the ejector 5.

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

[0042] A method for recovering energy from coal chemical gasification black water by using the coal chemical gasification black water energy recovery system described above, the method comprising the following steps:

[0043] The gasification black water with a temperature of 230-260℃ 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℃ and a pressure of 0.5-0.8 MPa and low-temperature black water with a temperature of 150-170℃ 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 power generation, and the expanded normal-pressure saturated black water with a temperature of 35-45℃ is transported to the vacuum flash tank 3 for vacuum flash;

[0045] The low-temperature steam generated by the vacuum flash tank 3 is transported to the vacuum flash condenser 4 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 2 and input into the ejector 5, and the high-temperature steam of the high-pressure flash tank 1 is input into the ejector 5, so that three different quality steam / gas mixtures are mixed, and through the cooperation of the ejector 5 and the vacuum flash condenser 4, the negative pressure of -80 kPa in the vacuum flash tank 3 is maintained.

[0046] The steam-water mixture of the ejector 5 is transported to the hot water tower 6, fresh water with a temperature of 15-25°C is supplemented at the upper part of the hot water tower 6, and shift condensate with a temperature of 40-60°C is supplemented at 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 section, and the grey water at the bottom of the hot water tower 6 is discharged.

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

[0048] The condensed water of the vacuum flash condenser 4 is transported to the grey water tank 7, the grey water of the grey water tank 7 is transported to the settling tank 8, and the saturated liquid black water of the vacuum flash tank 3 is transported to the settling tank 8 to be mixed with the grey water for settling, and the high-concentration liquid precipitated from the settling tank 8 is transported to the vacuum belt filter 9 for filtration.

[0049] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A coal chemical gasification black water energy recovery system, characterized in that: 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 ejector (5) and a hot water tower (6), the high-pressure flash tank (1) is provided with a gasification 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 an atmospheric saturated black water outlet (203), the vacuum flash tank (3) is provided with an atmospheric 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 ejector (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 shift condensate inlet (603), a hot water outlet (604) and a grey water outlet (605). The gasification black water inlet (101) of the high-pressure flash tank (1) is used for inputting gasification black water, the high-temperature steam outlet (102) of the high-pressure flash tank (1) is communicated with the high-temperature steam inlet (501) of the ejector (5) through a pipeline, and the low-temperature black water outlet (103) of the high-pressure flash tank (1) is communicated with 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 communicated with the mixed steam inlet (502) of the ejector (5) through a pipeline and after being connected with the uncondensed gas outlet (402) of the vacuum flash condenser (4), and the atmospheric saturated black water outlet (203) of the black water liquid expander (2) is communicated with the atmospheric 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 communicated with 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 for discharging liquid black water. The uncondensed gas outlet (402) of the vacuum flash condenser (4) is communicated with the mixed steam inlet (502) of the ejector (5) through a pipeline, and the condensed water outlet (403) of the vacuum flash condenser (4) is used for discharging condensed grey water. The steam-water mixture outlet (503) of the ejector (5) is communicated with 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 for inputting fresh cold water, the shift condensate inlet (603) of the hot water tower (6) is used for inputting shift condensate, the hot water outlet (604) of the hot water tower (6) is used for outputting hot water, and the grey water outlet (605) of the hot water tower (6) is used for discharging grey water.

2. The 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 regulating 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 arranged 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 arranged 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 ejector (5), a third regulating valve (12) is arranged on the pipeline at the superheated steam outlet (202) of the black water liquid expander (2), and a fourth regulating valve (13) is arranged on the pipeline at the mixed steam inlet (502) of the ejector (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 further comprises a gray water tank (7), a settling tank (8) and a vacuum belt filter (9) which are sequentially connected, and the condensate water outlet (403) of the vacuum flash condenser (4) is connected to the gray water tank (7) through a pipeline, and the saturated liquid black water outlet (303) of the vacuum flash tank (3) is connected to the settling tank (8) through a pipeline.

6. A method for energy recovery of coal chemical gasification black water by using the coal chemical gasification black water energy recovery system according to any one of claims 1-5, characterized in that: The method comprises the following steps: The gasification black water with a temperature of 230-260℃ and a pressure of 5.5-6.5MPa is sent to the high-pressure flash tank (1) for high-pressure flash separation, and high-temperature steam with a temperature of 150-180℃ and a pressure of 0.5-0.8MPa and low-temperature black water with a temperature of 150-170℃ and a pressure of 0.5-0.6MPa are output; The low-temperature black water is sent to the black water liquid expander (2) for expansion power generation, and the expanded normal-pressure saturated black water with a temperature of 35-45℃ is sent to the vacuum flash tank (3) for vacuum flash; The low-temperature steam generated by the vacuum flash tank (3) is sent to the vacuum flash condenser (4) for condensation, the condensate 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 ejector (5), and the high-temperature steam of the high-pressure flash tank (1) is input into the ejector (5) to mix three different quality steams / gases, and the cooperation of the ejector (5) and the vacuum flash condenser (4) maintains the negative pressure of the vacuum flash tank (3) at-80kPa; The steam-water mixture of the ejector (5) is sent to the hot water tower (6), fresh water with a temperature of 15-25℃ is supplemented at the upper part of the hot water tower (6), shift condensate liquid with a temperature of 40-60℃ is supplemented at the middle part of the hot water tower (6), and the hot water output from the top of the hot water tower (6) is sent to the subsequent section, and the gray water at the bottom of the hot water tower (6) is discharged.

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

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