Coal gasification blackwater flash heat recovery system and method

Abstract

This invention provides a black water flash evaporation heat recovery system and method from coal gasification, belonging to the field of black water heat recovery technology. It includes a high-pressure black water component, a heat exchange and desorption component, and a low-pressure ash water component. The high-pressure black water component includes a high-pressure black water feed pipe, and the low-pressure ash water component includes a low-pressure ash water feed pipe. The heat exchange and desorption component includes a tower body, a high-pressure flash evaporation section, and an acid gas desorption section. The high-pressure black water feed pipe is connected to the inlet of the high-pressure flash evaporation section, which is connected to the acid gas desorption section. The inlet of the acid gas desorption section is connected to the low-pressure ash water feed pipe. The high-pressure flash evaporation section and the acid gas desorption section perform primary and secondary heat exchange on the high-pressure black water fed through the high-pressure black water feed pipe within a single tower. Simultaneously, the flash vapor entering the acid gas desorption section undergoes heat exchange while simultaneously enhancing deep desorption of acidic gas and removal of gaseous impurities, avoiding corrosion and wear on the pipeline and improving the black water treatment effect.

Description

Technical Field

[0001] This invention relates to the field of black water heat recovery technology, specifically to a black water flash evaporation heat recovery system and method for coal gasification. Background Technology

[0002] Currently, black water treatment systems in coal gasification plants generally adopt a one-to-one configuration of gasifier and black water treatment unit. Black water from the gasifier, scrubbing tower, and cyclone separator is depressurized and then sent to the high-pressure flash evaporation system through an angle valve.

[0003] In conventional processes, the depressurized black water enters a high-pressure flash evaporator for gas-liquid separation. Water vapor and acidic gases in the black water are released through flash evaporation and flow along the riser hood into the upper tray area of ​​the high-pressure flash evaporator, where they come into counter-current contact with deoxygenated water introduced from the top of the tower. The flash vapor is then condensed and heated to heat the ash water (after multi-stage flash evaporation and sedimentation clarification, the upper layer of low-suspended solids is recycled as clean water). The heated ash water falls into a high-temperature hot water tank and is ultimately returned to the gasification system for reuse.

[0004] Because black water contains a large amount of coal ash impurities, the high flash steam-ash water heat exchanger is prone to blockage after heat exchange. Therefore, existing technologies propose a retrofit scheme that replaces the shell-and-tube heat exchanger with an ash water humidification tower. However, for in-service production units, the separate retrofit mode of "high-pressure flash tower + independent humidification tower" results in a large space occupation and high cost due to the addition of the humidification tower and supporting foundations and pipelines.

[0005] To address the aforementioned issues, existing technologies, such as Chinese invention patent application number 202110094641.8, disclose a flash steam spray heat exchange system and method for black water from coal gasification. This system utilizes a high-efficiency condenser and a fillerless spray heat exchange device. The high-efficiency condenser includes pipelines and atomizing components, with the atomizing components located on the pipelines. The fillerless spray heat exchange device includes a tower body, a spray layer, and several mass transfer pipes. The tower body has no filler layer or filler material, and an air inlet is located on the tower body, connected to one end of the pipelines. The air inlet, mass transfer pipes, and spray layer are arranged sequentially from bottom to top. This achieves heat recovery from the flash steam, avoids system scaling, and the entire spray heat exchange system has a smaller structure, reducing space occupancy. However, this existing technology does not completely remove the acidic gases emitted from the high-pressure flash steam, which exacerbates pipeline corrosion and wear and reduces the black water treatment effect. Summary of the Invention

[0006] In view of this, the present invention provides a coal gasification black water flash steam heat recovery system to solve the technical problem that incomplete desorption of acidic gases emitted from high-pressure flash steam exacerbates pipeline corrosion and wear, and reduces the black water treatment effect.

[0007] It is also necessary to provide a method for recovering heat from flash evaporation of black water from coal gasification.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] A coal gasification black water flash evaporation heat recovery system includes a high-pressure black water component, a heat exchange and desorption component, and a low-pressure ash water component. The high-pressure black water component includes a high-pressure black water inlet pipe, and the low-pressure ash water component includes a low-pressure ash water inlet pipe. The heat exchange and desorption component includes a tower body, a high-pressure flash evaporation section located at the lower part of the tower body, and an acid gas desorption section located at the upper part of the tower body. The high-pressure black water inlet pipe is connected to the inlet of the high-pressure flash evaporation section, the high-pressure flash evaporation section is connected to the acid gas desorption section, and the inlet of the acid gas desorption section is connected to the low-pressure ash water inlet pipe to ensure complete desorption of acid gases during the heat exchange process.

[0010] Preferably, the acid gas desorption section includes a liquid collecting tray, a flash vapor riser, a connecting rod, a gas lifting cap, and a tower plate located within the tower body. The liquid collecting tray has several evenly spaced mounting holes, and there are several flash vapor risers. The number of mounting holes matches the number of flash vapor risers. The liquid collecting tray is located above the high-pressure flash section and below the tower plate, which is located below the feed pipe of the low-pressure ash water feed pipe. The circumferential sidewall of the liquid collecting tray is welded to the inner wall of the tower body. The flash vapor riser is welded to the liquid collecting tray through the mounting holes. The top of the flash vapor riser is connected to one end of the connecting rod, and the other end of the connecting rod is connected to the bottom of the gas lifting cap, allowing high-pressure flash vapor to overflow from the gap between the flash vapor riser and the gas lifting cap and exchange heat with the ash water on the tray for desorption.

[0011] Preferably, a liquid storage area is formed between the flash vapor riser pipe, the liquid collection tray, and the inner wall of the tower body. The low-pressure ash water assembly also includes a heat exchange ash water outlet pipe, which is connected to the tower body to communicate with the liquid storage area.

[0012] Preferably, the high-pressure black water assembly further includes a high-pressure flash steam outlet pipe and a black water outlet pipe, wherein the high-pressure flash steam outlet pipe is connected to the top outlet of the tower body, and the black water outlet pipe is connected to the bottom outlet of the tower body.

[0013] Preferably, the low-pressure ash water inlet pipe is connected to the inlet of the high-pressure flash evaporator, and the outlet of the high-pressure flash evaporator is connected to the heat exchange ash water outlet pipe.

[0014] Preferably, the high-pressure flash evaporation section includes a mass transfer tube disposed inside the tower body. The tower body is provided with a black water inlet. The mass transfer tube is located below the liquid collection tray. The black water inlet is located below the mass transfer tube. The black water inlet of the tower body is connected to the high-pressure black water feed pipe. The inlet of the mass transfer tube is connected to the low-pressure ash water feed pipe. The outlet of the mass transfer tube is connected to the heat exchange ash water outlet pipe.

[0015] Preferably, the high-pressure flash evaporation section includes a spray pipe, spray nozzles, and a shift condensate inlet pipe. The spray pipe is located between the liquid collection tray and the mass transfer pipe. There are several spray nozzles, which are evenly arranged on the spray pipe. The spray pipe is connected to the shift condensate inlet pipe.

[0016] Preferably, the mass transfer tubes are provided in several layers, and the mass transfer tubes are interconnected.

[0017] Preferably, the high-pressure flash evaporation section further includes a liquid collection hopper, which is located inside the tower body and below the black water inlet, and the bottom of the liquid collection hopper is connected to the black water outlet pipe.

[0018] A method for recovering heat from flash evaporation of black water in coal gasification, using a coal gasification black water flash evaporation heat recovery system as described above, includes the following steps:

[0019] Black water from the high-pressure black water feed pipe is transported to the low-pressure tower body for flash evaporation to generate flash steam. Simultaneously, low-pressure ash water from the low-pressure ash water feed pipe is transported to the mass transfer pipe and above the tower tray. The flash steam first exchanges heat with the low-pressure ash water in the mass transfer pipe. After heat exchange, the flash steam overflows through the gap between the flash steam riser pipe and the riser cap and exchanges heat with the ash water on the tower tray for secondary heat exchange and desorption, ensuring sufficient heat exchange. The low-pressure ash water after heat exchange is transported out through the heat exchange ash water outlet pipe.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention provides a coal gasification black water flash evaporation heat recovery system and method, including a high-pressure black water component, a heat exchange and desorption component, and a low-pressure ash water component. The high-pressure black water component includes a high-pressure black water feed pipe, and the low-pressure ash water component includes a low-pressure ash water feed pipe. The heat exchange and desorption component includes a tower body, a high-pressure flash evaporation section located at the lower part of the tower body, and an acid gas desorption section located at the upper part of the tower body. The high-pressure black water feed pipe is connected to the inlet of the high-pressure flash evaporation section, and the high-pressure flash evaporation section is connected to the acid gas desorption section. The inlet of the acid gas desorption section is connected to the low-pressure ash water feed pipe. Through the high-pressure flash evaporation section and the acid gas desorption section, the high-pressure black water fed into the high-pressure black water feed pipe undergoes primary and secondary heat exchange within a single tower. Simultaneously, the flash vapor entering the acid gas desorption section undergoes heat exchange while simultaneously enhancing the deep desorption of acidic gas and the removal of gaseous impurities, avoiding corrosion and wear on the pipeline and improving the black water treatment effect. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of a coal gasification black water flash evaporation heat recovery system.

[0023] The diagram shows: a coal gasification black water flash evaporation heat recovery system 10, a high-pressure black water component 100, a high-pressure black water feed pipe 110, a high-pressure flash vapor outlet pipe 120, a black water outlet pipe 130, a heat exchange and desorption component 200, a tower body 210, a black water inlet 211, a high-pressure flash evaporation section 220, a mass transfer pipe 221, a spray pipe 222, a spray nozzle 223, a conversion condensate inlet pipe 224, a collection hopper 225, an acid gas desorption section 230, a collection tray 231, a mounting hole 2311, a flash vapor riser pipe 232, a connecting rod 233, a riser cap 234, a tower plate 235, a storage area 236, a low-pressure ash water component 300, a low-pressure ash water feed pipe 310, and a heat exchange ash water outlet pipe 320. Detailed Implementation

[0024] To facilitate understanding of this application, a more comprehensive description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are also given. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] A coal gasification black water flash evaporation heat recovery system 10 includes a high-pressure black water component 100, a heat exchange and desorption component 200, and a low-pressure ash water component 300. The high-pressure black water component 100 includes a high-pressure black water inlet pipe 110, and the low-pressure ash water component 300 includes a low-pressure ash water inlet pipe 310. The heat exchange and desorption component 200 includes a tower body 210, a high-pressure flash evaporation section 220 disposed below the interior of the tower body 210, and an acid gas desorption section 230 disposed above the interior of the tower body 210. The high-pressure black water inlet pipe 110 is connected to the inlet of the high-pressure flash evaporation section 220, and the high-pressure flash evaporation section 220 is connected to the acid gas desorption section 230. The inlet of the acid gas desorption section 230 is connected to the low-pressure ash water inlet pipe 310, so as to ensure complete desorption of acid gas during the heat exchange process.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention provides a coal gasification black water flash evaporation heat recovery system 10 and method, including a high-pressure black water component 100, a heat exchange and desorption component 200, and a low-pressure ash water component 300. The high-pressure black water component 100 includes a high-pressure black water inlet pipe 110, the low-pressure ash water component 300 includes a low-pressure ash water inlet pipe 310, and the heat exchange and desorption component 200 includes a tower body 210, a high-pressure flash evaporation section 220 disposed below the interior of the tower body 210, and an acid gas desorption section 230 disposed above the interior of the tower body 210. The high-pressure black water inlet pipe 110 and the high-pressure... The inlet of the flash evaporation section 220 is connected to the acid gas desorption section 230, and the inlet of the acid gas desorption section 230 is connected to the low-pressure ash water feed pipe 310. Through the high-pressure flash evaporation section 220 and the acid gas desorption section 230, the high-pressure black water fed into the high-pressure black water feed pipe 110 is subjected to primary and secondary heat exchange in only one tower. At the same time, the flash vapor entering the acid gas desorption section 230 is subjected to heat exchange while strengthening the deep desorption of acid gas and the removal of gaseous impurities, avoiding corrosion and wear on the pipeline and improving the black water treatment effect.

[0029] Furthermore, the acid gas desorption unit 230 includes a liquid collection tray 231, flash vapor riser pipes 232, connecting rods 233, a gas riser cap 234, and a tower plate 235 located within the tower body 210. The liquid collection tray 231 has several evenly spaced mounting holes 2311. There are several flash vapor riser pipes 232, and the number of mounting holes 2311 matches the number of flash vapor riser pipes 232. The liquid collection tray 231 is located above the high-pressure flash evaporation unit 220 and below the tower plate 235. The tower plate 235 is located below the feed pipe of the low-pressure ash water feed pipe 310. The circumferential sidewall of the liquid collection tray 231 is flush with the tower body 210. The inner wall of the structure is welded, and the flash vapor riser pipe 232 is welded to the liquid collection tray 231 through the mounting hole 2311. The top of the flash vapor riser pipe 232 is connected to one end of the connecting rod 233, and the other end of the connecting rod 233 is connected to the bottom of the gas lifting cap 234, so that the high-pressure flash vapor overflows from the gap between the flash vapor riser pipe 232 and the gas lifting cap 234 and exchanges heat with the ash water on the tray for desorption. The high-pressure flash vapor overflows from the gap between the flash vapor riser pipe 232 and the gas lifting cap 234 and rises upward. The high-temperature flash vapor rises smoothly after being rectified by the flash vapor riser pipe 232, the connecting rod 233, and the gas lifting cap 234, completely eliminating the problems of heat loss from gas phase turbulence and ash and liquid carryover. After entering the heat exchange chamber of the upper tower, the low-temperature circulating ash water output from the low-pressure ash water feed pipe 310 is evenly distributed from top to bottom, forming a multi-level countercurrent phase change heat exchange with the upward high-temperature flash steam. Relying on the heat storage and interception mechanism, all the high and low grade waste heat is captured. At the same time, through the heat exchange, purification and gas release coupling gain effect, the deep analysis of acid gas and the removal of gas phase impurities are enhanced.

[0030] Meanwhile, the liquid collection tray 231 enables precise liquid collection and stable flow distribution, completely solving the problems of uneven liquid collection and frequent flooding in traditional towers.

[0031] Finally, the flash vapor enters below the riser cap 234 from the flash vapor riser 232. The flash vapor flow rate can be reduced and the gas phase residence time can be extended by using the flash vapor riser 232.

[0032] The ash water in the low-pressure ash water inlet pipe 310 can come from the settling tank of the ash water system.

[0033] Furthermore, a liquid storage area 236 is formed between the flash vapor riser 232, the liquid collection tray 231, and the inner wall of the tower body 210. The low-pressure ash water assembly 300 also includes a heat exchange ash water outlet pipe 320. The heat exchange ash water outlet pipe is connected to the tower body 210 to communicate with the liquid storage area 236. The ash water after heat exchange is collected in the liquid storage area 236 and then transported out through the heat exchange ash water outlet pipe 320, which can be used in the deaerator of the ash water system.

[0034] Furthermore, the high-pressure black water assembly 100 also includes a high-pressure flash vapor outlet pipe 120 and a black water outlet pipe 130. The high-pressure flash vapor outlet pipe 120 is connected to the top outlet of the tower body 210, and the black water outlet pipe 130 is connected to the bottom outlet of the tower body 210. The flash vapor after primary and secondary heat exchange is transported out through the high-pressure flash vapor outlet pipe 120, while the liquid black water is discharged through the black water outlet pipe 130.

[0035] Furthermore, the low-pressure ash water inlet pipe 310 is connected to the inlet of the high-pressure flash evaporation section 220, and the outlet of the high-pressure flash evaporation section 220 is connected to the heat exchange ash water outlet pipe 320, so that heat exchange can be performed through the high-pressure flash evaporation section 220.

[0036] Furthermore, the high-pressure flash evaporation section 220 includes a mass transfer pipe 221 disposed inside the tower body 210. The tower body 210 is provided with a black water inlet 211. The mass transfer pipe 221 is located below the liquid collection tray 231. The black water inlet 211 is located below the mass transfer pipe 221. The black water inlet 211 of the tower body is connected to the high-pressure black water feed pipe 110. The inlet of the mass transfer pipe 221 is connected to the low-pressure ash water feed pipe 310. The outlet of the mass transfer pipe 221 is connected to the heat exchange ash water outlet pipe 320. The liquid collection tray 231 divides the interior of the tower body 210 into... The high-pressure flash evaporation section 220 (primary heat exchange) and the acid gas desorption section 230 (secondary heat exchange) introduce the low-pressure circulating ash water from the low-pressure ash water feed pipe 310 into the system in two paths. One path of ash water enters the mass transfer pipe 221, and the other path enters the tray for flash steam washing and humidification. The high-temperature and high-pressure black water enters the high-pressure flash evaporation section 220 for depressurized flash evaporation. The high-temperature flash steam undergoes counter-current heat exchange with the low-pressure ash water in the mass transfer pipe 221 to recover high-grade waste heat. At the same time, it achieves scale prevention and pre-protection of the inner wall of the mass transfer pipe 221. The preheated ash water is transported out through the heat exchange ash water outlet pipe 320 for recycling.

[0037] Furthermore, the high-pressure flash evaporation section 220 includes a spray pipe 222, spray nozzles 223, and a shift condensate inlet pipe 224. The spray pipe 222 is located between the liquid collection tray 231 and the mass transfer pipe 221. There are several spray nozzles 223, which are evenly arranged on the spray pipe 222. The spray pipe 222 is connected to the shift condensate inlet pipe 224.

[0038] By integrating the flash vapor riser pipe 232, connecting rod 233, and riser cap 234 with the built-in spray pipe 222, spray nozzle 223, and change condensate inlet pipe 224, the rising flash vapor can be atomized and washed throughout the process, effectively removing impurities such as coal ash and solid dust carried in the flash vapor, and eliminating tray blockage failure from the root.

[0039] Furthermore, the mass transfer tube 221 is provided in several layers, and the several mass transfer tubes 221 are interconnected. Through the several layers of mass transfer tubes 221, uniform feeding and flash evaporation of black water can be achieved, avoiding the problems of excessively high local black water concentration and insufficient flash evaporation, significantly improving the desorption efficiency of acidic gases such as hydrogen sulfide and carbon dioxide in black water, and solving the defects of incomplete desorption of acidic gases and severe acid corrosion of pipelines caused by uneven liquid distribution in traditional pipelines.

[0040] Furthermore, the high-pressure flash evaporation section 220 also includes a liquid collection hopper 225, which is located inside the tower body 210 and below the black water inlet 211. The bottom of the liquid collection hopper 225 is connected to the black water outlet pipe 130.

[0041] The aforementioned pipeline interfaces are connected using flange sealing and fastening.

[0042] A method for recovering heat from flash evaporation of black water in coal gasification, using a coal gasification black water flash evaporation heat recovery system 10 as described above, includes the following steps:

[0043] Black water in the high-pressure black water feed pipe 110 is transported to the low-pressure tower body 210 for flash evaporation to generate flash steam. At the same time, low-pressure ash water in the low-pressure ash water feed pipe 310 is transported to the mass transfer pipe 221 and above the tower plate 235. The flash steam first exchanges heat with the low-pressure ash water in the mass transfer pipe 221. The flash steam after heat exchange overflows through the gap between the flash steam riser pipe 232 and the riser cap 234 and exchanges heat with the ash water on the tower plate 235 for secondary heat exchange and desorption to ensure sufficient heat exchange. The low-pressure ash water after heat exchange is transported out through the heat exchange ash water outlet pipe 320.

[0044] The high-pressure black water conveyed in the high-pressure black water inlet pipe 110 has a pressure of 0.8 MPa (G) and a temperature of 160~180℃.

[0045] The low-pressure ash water conveyed in the low-pressure ash water inlet pipe 310 has a pressure of 0.2 to 0.4 MPa (G) and a temperature of 65 to 70°C.

[0046] The temperature of the grey water after heat exchange inside mass transfer tube 221 is 110–125℃.

[0047] The temperature of the ash water after heat exchange on the collecting tray 231 is 110–125℃.

[0048] Through the above-mentioned primary and secondary heat exchange, the temperature of the heat exchange ash water outlet pipe 320 is 110-125℃, which meets the design medium temperature of the original high-pressure ash water pump. This will prevent cavitation at the pump inlet from easily causing cavitation due to long-term transportation of high-temperature ash water, thus avoiding threats to the safe operation of the pump.

[0049] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A coal gasification black water flash evaporation heat recovery system, characterized in that, The system includes a high-pressure black water assembly, a heat exchange and desorption assembly, and a low-pressure ash water assembly. The high-pressure black water assembly includes a high-pressure black water inlet pipe, and the low-pressure ash water assembly includes a low-pressure ash water inlet pipe. The heat exchange and desorption assembly includes a tower body, a high-pressure flash evaporation section located at the lower part of the tower body, and an acid gas desorption section located at the upper part of the tower body. The high-pressure black water inlet pipe is connected to the inlet of the high-pressure flash evaporation section, and the high-pressure flash evaporation section is connected to the acid gas desorption section. The inlet of the acid gas desorption section is connected to the low-pressure ash water inlet pipe to ensure complete desorption of acid gases during the heat exchange process.

2. The coal gasification black water flash evaporation heat recovery system as described in claim 1, characterized in that, The acid gas desorption section includes a liquid collection tray, flash vapor riser, connecting rod, gas riser cap, and tower plate located within the tower body. Several mounting holes are evenly distributed on the liquid collection tray. There are several flash vapor risers, with the number of mounting holes matching the number of flash vapor risers. The liquid collection tray is located above the high-pressure flash section and below the tower plate, which is located below the feed pipe of the low-pressure ash water feed pipe. The circumferential sidewall of the liquid collection tray is welded to the inner wall of the tower body. The flash vapor riser is welded to the liquid collection tray through the mounting holes. The top of the flash vapor riser is connected to one end of the connecting rod, and the other end of the connecting rod is connected to the bottom of the gas riser cap, allowing high-pressure flash vapor to overflow from the gap between the flash vapor riser and the gas riser cap and exchange heat with the ash water on the tower tray for desorption.

3. The coal gasification black water flash evaporation heat recovery system as described in claim 2, characterized in that, The flash vapor riser pipe forms a liquid storage area between the liquid collection tray and the inner wall of the tower body. The low-pressure ash water assembly also includes a heat exchange ash water outlet pipe, which is connected to the tower body to communicate with the liquid storage area.

4. The coal gasification black water flash evaporation heat recovery system as described in claim 1, characterized in that, The high-pressure black water assembly also includes a high-pressure flash steam outlet pipe and a black water outlet pipe. The high-pressure flash steam outlet pipe is connected to the top outlet of the tower body, and the black water outlet pipe is connected to the bottom outlet of the tower body.

5. The coal gasification black water flash evaporation heat recovery system as described in claim 3, characterized in that, The low-pressure ash water inlet pipe is connected to the inlet of the high-pressure flash evaporator, and the outlet of the high-pressure flash evaporator is connected to the heat exchange ash water outlet pipe.

6. The coal gasification black water flash evaporation heat recovery system as described in claim 5, characterized in that, The high-pressure flash evaporation section includes a mass transfer tube disposed inside the tower body. The tower body is provided with a black water inlet. The mass transfer tube is located below the liquid collection tray. The black water inlet of the tower body is located below the mass transfer tube. The black water inlet of the tower body is connected to the high-pressure black water feed pipe. The inlet of the mass transfer tube is connected to the low-pressure ash water feed pipe. The outlet of the mass transfer tube is connected to the heat exchange ash water outlet pipe.

7. The coal gasification black water flash evaporation heat recovery system as described in claim 6, characterized in that, The high-pressure flash evaporation section includes a spray pipe, spray nozzles, and a shift condensate inlet pipe. The spray pipe is located between the liquid collection tray and the mass transfer pipe. There are several spray nozzles, which are evenly arranged on the spray pipe. The spray pipe is connected to the shift condensate inlet pipe.

8. The coal gasification black water flash evaporation heat recovery system as described in claim 6, characterized in that, The mass transfer tubes are arranged in several layers, and the mass transfer tubes are connected to each other.

9. The coal gasification black water flash evaporation heat recovery system as described in claim 7, characterized in that, The high-pressure flash evaporation section also includes a liquid collection hopper, which is located inside the tower body and below the black water inlet. The bottom of the liquid collection hopper is connected to the black water outlet pipe.

10. A method for recovering heat from flash evaporation of black water from coal gasification, characterized in that, Using a coal gasification black water flash evaporation heat recovery system as described in any one of claims 1-9 includes the following steps: Black water from the high-pressure black water feed pipe is transported to the low-pressure tower body for flash evaporation to generate flash steam. Simultaneously, low-pressure ash water from the low-pressure ash water feed pipe is transported to the mass transfer pipe and above the tower tray. The flash steam first exchanges heat with the low-pressure ash water in the mass transfer pipe. After heat exchange, the flash steam overflows through the gap between the flash steam riser pipe and the riser cap and exchanges heat with the ash water on the tower tray for secondary heat exchange and desorption, ensuring sufficient heat exchange. The low-pressure ash water after heat exchange is transported out through the heat exchange ash water outlet pipe.

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