A high-pressure flash tower for coal gasification and a method for treating black water

Abstract

This invention discloses a high-pressure flash evaporator for coal gasification and its black water treatment method, belonging to the field of black water treatment technology in coal chemical industry. The flash evaporator integrates a heat exchange device, an ash water collection tank, and a washing device arranged sequentially from top to bottom, combining flash evaporation, dust removal, heat exchange, and online cleaning into one unit. The washing system can switch between low-temperature ash water and condensate from two sources, employing multi-layer herringbone baffles and a full-area spray structure, along with a differential pressure linkage valve group to achieve online cleaning without shutting down the system. The ash water collection tank is compatible with both horizontal and inclined bottom plate structures, with the inclined bottom plate equipped with a downcomer and overflow weir to adapt to different slag-containing conditions. The heat exchange device uses staggered multi-layer trays, significantly improving gas-liquid heat exchange efficiency. This invention solves the problems of easy clogging, poor heat exchange, high demineralized water consumption, and weak adaptability of traditional equipment, simplifying the process flow, reducing equipment investment and maintenance costs, ensuring stable equipment operation, energy saving, and anti-clogging performance, adapting to various chemical production conditions, and possessing high application value.

Description

Technical Field

[0001] This invention belongs to the field of coal gasification black water reuse technology, specifically relating to a coal gasification high-pressure flash evaporation tower and black water treatment method that integrates flash evaporation, dust removal, heat exchange and online cleaning. Background Technology

[0002] The coal gasification black water treatment section is a core supporting unit for the stable operation of the coal gasification plant. It is mainly used to perform depressurization flash evaporation, heat recovery, gas-liquid separation and acid gas desorption on the high temperature, high pressure and solid content black water discharged from the gasifier, washing tower and cyclone separator, so as to provide qualified circulating water for the gasification system and achieve energy saving and emission reduction while meeting environmental protection standards.

[0003] Traditional blackwater treatment systems typically employ a multi-stage flash evaporation process combined with fixed trays and settling separators, using high-pressure and low-pressure flash steam to heat the ash water. However, due to the significant ash and slag content of blackwater, long-term operation presents the following problems: 1. High flash tower trays are prone to scaling, clogging, and flooding, which seriously affect flash evaporation efficiency and system stability.

[0004] 2. The grey water heater is prone to scaling, resulting in low heat exchange efficiency. It usually needs to be shut down for cleaning after three months of operation, which affects the long-term operation of the unit.

[0005] 3. Excessive cooling temperature of black water causes incomplete desorption of acidic gas, accelerating corrosion of equipment and pipelines.

[0006] 4. Cleaning requires the use of external demineralized water, resulting in high water consumption and operating costs.

[0007] To address the common challenges facing the industry, several technological improvements and patent innovations have been implemented. For example, CN118289874A discloses "A High Flash Stream Tower and Method for Treating Black Water from Coal Gasification," which optimizes the high flash stream tower body by adding a separation cylinder, baffles, a liquid descending cylinder, a flash steam rising cylinder with a contraction section, and a spray washing assembly. This allows the flash steam in the separation cylinder to remove solid impurities and reduces the risk of pipeline wear. Simultaneously, deaerators and demisters are installed on the upper part of the high flash stream tower to further purify the gas flow and clean the trays. However, this technology still requires an additional ash water heater to recover the heat from the high flash gas, lacking an integrated anti-clogging and energy-saving design, and also necessitates external supply of demineralized water for cleaning.

[0008] For example, CN 106621415 B discloses a "tray-type flash evaporation-heat exchange integrated equipment," which divides a high-pressure flash evaporation tower into a lower evaporation chamber and an upper hot water chamber through a tower body partition. The hot water chamber consists of a demister, an inlet distributor, and a tower tray from top to bottom. The two chambers are connected by a riser pipe, which can achieve flash evaporation of solid wastewater, solid-phase separation, and heating of clean water in a single tower. However, this equipment lacks a pre-dust removal and washing structure, an online automatic cleaning system, and a self-circulating supply of ash water, thus failing to solve the problems of clogging and high water consumption at the source.

[0009] In summary, current technologies have not yet achieved an integrated design of anti-clogging, cleaning, and energy saving for high-pressure flash towers. There is still considerable room for improvement in the research on anti-clogging, online cleaning, and integrated flashing and heat exchange of high-pressure flash towers. Summary of the Invention

[0010] The present invention aims to overcome the shortcomings of the prior art and provide a coal gasification high-pressure flash tower and method that integrates anti-clogging, online cleaning, flash evaporation and heat exchange. This invention addresses the technical pain points of the prior art, such as the easy clogging of the tower tray by dust entrained in flash steam and the large consumption of demineralized water in black water reuse projects, and achieves long-term, stable and efficient operation of the coal gasification high-pressure flash tower.

[0011] To achieve the above objectives, the first aspect of the present invention provides a high-pressure flash distillation tower for coal gasification, which adopts the following technical solution: A high-pressure flash tower for coal gasification includes a tower body. Inside the tower body, a heat exchange device, an ash water collection tank, and a washing device are arranged sequentially along an axial direction from top to bottom, forming a layered functional layout of heat exchange, water collection, and washing from top to bottom. The outside of the tower body integrates a black water inlet, a flash steam outlet, an ash water inlet, an ash water outlet, a black water discharge outlet, and a waste residue outlet, with each port precisely matching the process flow medium inlet and outlet requirements.

[0012] The washing device includes a herringbone baffle and a spray system. The spray system consists of a washing water pipe, washing water nozzles, and a washing water valve group. The washing water valve group is centrally located outside the tower body for easy maintenance and control. The washing water pipe is connected to the main washing water pipe through the washing water valve group. The main washing water pipe is connected to an external washing water source to achieve a stable supply of washing water and controllable flow adjustment.

[0013] The grey water collection tank includes a base plate, a collection tank air riser pipe, and an inverted U-shaped baffle. Several collection tank air risers are provided, and multiple sets of collection tank air risers are evenly arranged and fixed above the base plate. An inverted U-shaped baffle is provided above the top of each layer of collection tank air risers. The baffle structure realizes airflow deflection and droplet interception, thereby enhancing the secondary gas-liquid separation effect.

[0014] The heat exchange device is composed of multiple layers of trays arranged in an alternating pattern, which effectively extends the gas-liquid contact heat exchange path, increases the heat exchange contact area, and improves the efficiency of flash vapor cooling and heat recovery.

[0015] In a preferred embodiment of the present invention, the black water inlet is located in the lower region of the washing device to ensure that the high-temperature and high-pressure black water directly enters the flash evaporation zone at the bottom of the tower, achieving rapid pressure reduction and flash evaporation; the flash steam outlet is located at the center of the upper part of the tower body to facilitate the uniform discharge of clean flash steam; the ash water inlet is located in the upper region of the heat exchange device to form a top-down ash water spray heat exchange path, forming a counter-current heat exchange system with the bottom-up flash steam; the ash water outlet is located on the side of the ash water collection tank and is connected to the ash water pump for stable drainage; the black water discharge port is located at the lower outer side of the tower body for system sewage discharge; and the waste residue outlet is located at the center of the lower part of the tower body to facilitate the concentrated discharge of bottom-deposited waste residue.

[0016] As a preferred embodiment of the present invention, the washing water source is low-temperature grey water or a variable condensate, which can be flexibly switched according to the operating conditions of the device to adapt to different production loads and water quality conditions, thereby realizing the resource utilization of wastewater and reducing the process water consumption cost.

[0017] As a preferred embodiment of the present invention, the herringbone baffle and the washing water pipe are both provided with several layers, and a multi-layer staggered arrangement structure is adopted. Herringbone baffles are correspondingly set between two adjacent layers of washing water pipes, and the layer matching is precise. Several washing water nozzles are evenly distributed on the side of the washing water pipe near the herringbone baffle to achieve full-area spray coverage without dead corners, ensuring that the flash vapor is in full contact with the herringbone baffle and the washing water, thereby enhancing the dust removal and purification effect.

[0018] As a preferred embodiment of the present invention, the washing water valve assembly adopts a washing water regulating valve or a washing water on / off valve. The regulating valve can achieve stepless and precise control of the washing water flow, while the on / off valve can achieve rapid switching between on and off, adapting to different washing and cleaning conditions.

[0019] As a preferred embodiment of the present invention, the bottom plate of the water collection tank can be a horizontal or inclined structure, with flexible structural options to suit the usage requirements of equipment with different installation precision and different slag content, thus providing stronger adaptability to operating conditions.

[0020] As a preferred embodiment of the present invention, when the bottom plate of the water collection tank is a horizontal structure, the grey water outlet is directly connected to the bottom plate of the water collection tank, and the lower side of the grey water outlet pipe is flush with the bottom plate of the water collection tank, which can completely avoid grey water residue and impurity deposition, and ensure clean and smooth drainage.

[0021] As a preferred embodiment of the present invention, when the bottom plate of the water collection tank is an inclined structure, a downcomer and an overflow weir are provided between the ash water outlet and the bottom plate of the water collection tank. The downcomer is fixedly connected to the end of the bottom plate of the water collection tank, and the overflow weir is assembled below the downcomer and communicates with the ash water outlet. The overflow weir stabilizes the liquid level inside the water collection tank, realizing the steady and quantitative discharge of ash water. The downcomer guides the liquid phase to flow smoothly, avoiding liquid splashing and airflow disturbance, and stabilizing the operating conditions inside the tower.

[0022] As a preferred embodiment of the present invention, differential pressure transmitters are installed upstream and downstream of the herringbone baffle. The differential pressure transmitters are linked with the valve group of the spray system for control. They can monitor the airflow pressure difference before and after the baffle in real time. When the pressure difference reaches the system's preset blockage threshold, the spray system is automatically triggered to increase the washing water flow rate to complete the online cleaning operation inside the tower without stopping the machine, thus realizing automated operation and maintenance of the equipment.

[0023] A second aspect of the present invention provides a method for treating black water from a high-pressure flash distillation tower for coal gasification, based on any one of the above-mentioned high-pressure flash distillation towers, comprising the following steps: S1. Flash Evaporation and Pressure Reduction: High-temperature and high-pressure slag-containing black water is sent into the tower body through the black water inlet at the bottom of the tower body. The high-pressure black water experiences a sudden pressure drop in the low-pressure environment inside the tower, resulting in an adiabatic flash evaporation phase change. This process separates the black water into high-temperature flash steam and black water residue. Large particles of waste residue settle to the bottom of the tower body and are eventually discharged through the waste residue outlet.

[0024] S2. Spray washing and dust removal: The flash steam generated by flash evaporation enters the washing device area from bottom to top. The system selects low-temperature ash water or converted condensate as the washing water source. The water supply flow is regulated by an external valve group. The washing water is delivered to the washing water nozzles through the washing water pipe and sprayed out evenly. The flash steam is rectified and deflected by multiple herringbone baffles in stages, which prolongs the gas-liquid contact residence time and makes full countercurrent contact with the spray washing water, effectively removing the fine ash and residual slag carried in the flash steam, and completing the primary dust removal and purification.

[0025] S3. Precise gas-liquid separation: After washing and dust removal, the flash vapor continues to rise into the ash water collection tank area. It rises evenly through multiple sets of collection tank riser pipes. Under the obstruction and guidance of the inverted U-shaped baffle, the airflow direction is forcibly changed. The fine mist droplets and suspended ash slag carried in the airflow are completely separated from the gas phase under the dual action of gravity settling and inertial separation, and flow back into the bottom plate of the ash water collection tank, realizing deep gas-liquid separation of flash vapor.

[0026] S4. Countercurrent heat exchange for heat recovery: The clean flash vapor, after gas-liquid separation, continues to rise and enters the heat exchange device at the top of the tower. The low-temperature ash water enters the tower through the ash water inlet above the heat exchange device, forming a uniform liquid film on the surface of the multi-layered staggered tower plates. It fully countercurrently contacts and directly exchanges heat with the high-temperature flash vapor rising from the bottom. The clean flash vapor, after being cooled by heat exchange, is finally sent out from the flash vapor outlet at the top of the tower to the subsequent process. The heated ash water falls down the tower plates and flows into the ash water collection tank, and is stably discharged through the ash water outlet, realizing efficient heat recovery and ash water recycling.

[0027] S5. Automated Online Cleaning: During equipment operation, differential pressure transmitters upstream and downstream of the herringbone baffle collect differential pressure data in real time and upload it to the system. When the differential pressure rises to a preset threshold, it is determined that there is ash accumulation and blockage in the baffle and tower. The system automatically adjusts the washing water regulating valve to increase the spray flow or opens the washing water switch valve to perform high-pressure online flushing of the herringbone baffle and the airflow channel in the tower, promptly removing accumulated ash and scale, reducing equipment differential pressure, and ensuring continuous and stable operation of the equipment without stopping the entire process.

[0028] Compared with the prior art, the beneficial effects of the present invention are: This invention is highly integrated and saves investment. It integrates four major functions—flash evaporation, dust removal, heat exchange, and online cleaning—within a single tower, eliminating the need for an external ash water heater, thus significantly reducing equipment investment and floor space.

[0029] This invention features dual anti-clogging and extended cleaning cycles. The front-mounted herringbone baffle spray dust removal system removes ash and slag carried by flash vapor at the source. Combined with the anti-clogging tray structure, this dual protection prevents tray blockage and flooding, significantly extending the tray cleaning cycle.

[0030] This invention saves energy and water, reduces costs, and allows flash steam and ash water to directly contact and exchange heat on the tower plate, resulting in high heat exchange efficiency. The washing water is supplied by a self-circulating ash water system, eliminating the need for external demineralized water and significantly reducing water consumption and operating costs.

[0031] This invention features automated operation and maintenance, eliminating the need for system shutdown. It monitors the differential pressure in real time through differential pressure transmitters upstream and downstream of the herringbone baffle, and controls the washing water flow accordingly, enabling online automatic cleaning. The cleaning operation can be completed without shutdown, extending the continuous operation cycle of the device.

[0032] This invention is environmentally friendly and safe, reduces corrosion, ensures sufficient heat exchange, and allows for more complete desorption of acidic gases, effectively slowing down the corrosion rate of equipment and pipelines and ensuring the safe operation of the device. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a high-intensity flash tower structure in the prior art (patent CN118289874A); Figure 2This is a schematic diagram of the structure of the high-pressure flash evaporator (water collection tank bottom plate is horizontal) for coal gasification according to the present invention; Figure 3 This is a schematic diagram of the structure of the high-pressure flash evaporator for coal gasification (with an inclined bottom plate of the water collection tank) of the present invention; In the diagram: 1. Tower body; 2. Washing device; 3. Ash water collection tank; 4. Heat exchange device; 5. Black water inlet; 6. Flash steam outlet; 7. Ash water inlet; 8. Ash water outlet; 9. Black water discharge outlet; 10. Waste residue outlet; 11. Washing water pipe; 12. Washing water nozzle; 13. Herringbone baffle; 14. Collection tank bottom plate; 15. Collection tank riser pipe; 16. Inverted U-shaped baffle; 17. Tower plate; 18. Ash water pump; 19. Washing water main pipe; 20. Washing water regulating valve; 21. Washing water on / off valve; 22. Downcomer; 23. Overflow weir. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Example 1

[0038] See Figure 2This embodiment is applied to the conventional continuous production conditions of 100% full load and medium slag content black water in a large coal chemical plant. The equipment adopts the integrated structure of this invention. The core adopts the horizontal water collection tank bottom plate (14) structure. The whole machine integrates flash evaporation, anti-clogging dust removal, high-efficiency heat exchange and online self-cleaning functions. There is no need for an external ash water heater. The structure has high integration and is easy to operate and maintain.

[0039] The overall structure of the equipment in this embodiment is assembled as follows: the main body of the equipment is a vertical tower (1), and the heat exchange device (4), the ash water collection tank (3), and the washing device (2) are fixedly assembled inside the tower (1) from top to bottom, forming a layered and orderly process processing area. The process ports are precisely arranged on the outside of the tower body (1): the black water inlet (5) is located in the area below the washing device (2) to ensure that the high temperature black water enters the flash evaporation zone quickly; the flash steam outlet (6) is located at the center of the top of the tower body (1) to uniformly discharge clean flash steam; the ash water inlet (7) is located above the heat exchange device (4) to form a countercurrent heat exchange medium passage; the ash water outlet (8) is arranged on the side of the ash water collection tank (3), and the lower side of the pipe is flush with the bottom plate (14) of the horizontal structure collection tank, with no dead corners of liquid accumulation and slag accumulation. The ash water outlet (8) is connected to the ash water pump (18) to achieve stable liquid discharge; the black water discharge port (9) is set at the bottom of the outside of the tower body (1) for system sewage discharge, and the waste residue outlet (10) is set at the center of the bottom of the tower body (1) for the centralized discharge of deposited waste residue.

[0040] The washing device (2) adopts a staggered structure of multi-layer herringbone baffles (13) and multi-layer washing water pipes (11). Herringbone baffles (13) are set between adjacent layers of washing water pipes (11). Washing water nozzles (12) are evenly and densely distributed on the side of the washing water pipes (11) facing the herringbone baffles (13) to achieve full-area spray coverage. The spray system pipeline is integrated externally. The washing water pipes (11) are connected to the washing water main pipe (19) through pipelines. In this embodiment, the device's own low-temperature grey water is normally selected as the washing water source. The valve group adopts a washing water regulating valve (20), which can steplessly and accurately control the spray flow rate and adapt to the full-load stable washing conditions. Differential pressure transmitters are installed upstream and downstream of the herringbone baffles (13) to monitor the equipment operating differential pressure in real time.

[0041] The grey water collection tank (3) adopts a horizontal collection tank bottom plate (14). Multiple sets of collection tank air risers (15) are evenly arranged above the bottom plate. Each set of collection tank air risers (15) is equipped with an inverted U-shaped baffle (16) at the top. The baffle forces the airflow to change direction, intercepts gas droplets and fine ash, and achieves efficient secondary gas-liquid separation. The horizontal bottom plate flush drainage structure can completely eliminate media residue and impurity accumulation.

[0042] The heat exchange device (4) adopts a multi-layer staggered tower plate (17) structure, which effectively extends the gas-liquid heat exchange contact path, increases the heat exchange area, improves the waste heat recovery efficiency, eliminates the traditional external heat exchange equipment, and greatly reduces equipment investment and land occupation.

[0043] The specific operating process steps in this embodiment are as follows: Step 1, Flash Evaporation and Pressure Reduction: High-temperature and high-pressure slag-containing black water with a temperature of 240℃ and a pressure of 4.0MPa is sent into the tower body (1) through the black water inlet (5). The tower is stabilized at 0.8MPa to achieve rapid adiabatic flash evaporation, which separates the high-temperature flash steam and black water residue. Large particles of waste residue settle to the bottom of the tower and are discharged from the waste residue outlet (10).

[0044] Step 2, Washing and Dust Removal: Flash steam flows from bottom to top through multiple layers of herringbone baffles (13) for rectification and deflection. The low-temperature ash water spray flow rate is controlled at 8-10 m³ / h by the washing water regulating valve (20). The entire area is sprayed to remove gaseous fine ash impurities, thus preventing the tower plate (17) from clogging at the source.

[0045] Step 3, gas-liquid separation: After dust removal, the flash vapor rises through the riser pipe (15) of the water collection tank, and is intercepted by the inverted U-shaped baffle (16). The fine droplets and ash fall back into the water collection tank, completing the deep gas-liquid separation. Step 4, Countercurrent heat exchange: 80℃ low-temperature ash water enters through the ash water inlet (7) and directly exchanges heat with high-temperature flash steam in a countercurrent manner on the multi-layer staggered tower plate (17). The cooled clean flash steam is sent out through the flash steam outlet (6). The heated ash water is collected in the water collection tank and then discharged stably through the ash water outlet (8) and ash water pump (18).

[0046] Step 5, Online Cleaning: When the system pressure difference percentage exceeds 60-80% of normal operation, the washing water regulating valve (20) is automatically adjusted to increase the spray flow rate, and the accumulated dust and scale are rinsed online without stopping the machine.

[0047] Implementation Results: This embodiment achieves multi-functional integration of a single tower, eliminating the need for an external ash water heater, significantly reducing equipment investment and floor space; the pre-spray dust removal combined with the anti-clogging tower plate structure completely solves the problem of tower tray blockage under full load conditions, greatly extending the continuous operation cycle of the equipment; the use of low-temperature ash water self-circulation washing eliminates the need for demineralized water consumption, resulting in significant water saving and energy reduction; the fully automated online cleaning eliminates the need for manual shutdown for cleaning, reducing operation and maintenance costs, while sufficient heat exchange can completely decompose acidic gases, slowing down equipment pipeline corrosion and ensuring long-term stable and safe operation of the unit.

[0048] Example 2

[0049] See Figure 3 This embodiment is adapted to harsh production scenarios with high slag content, high dust concentration and frequent fluctuations in operating conditions in coal gasification black water. Compared with embodiment 1, this embodiment adopts an inclined water collection tank bottom plate (14) as the core, and adds a downcomer plate (22) and an overflow weir (23) structure to optimize the stability of liquid level and slag discharge capacity under high slag conditions. At the same time, the washing and cleaning configuration is upgraded to enhance the equipment's anti-clogging performance and adaptability to harsh operating conditions.

[0050] The overall basic layout of the equipment in this embodiment is the same as that in embodiment 1. The heat exchange device (4), ash water collection tank (3), and washing device (2) are arranged from top to bottom inside the tower body (1). The positions of each process port are matched to meet the requirements of medium inlet and outlet and sewage discharge and slag discharge under harsh working conditions. The core differentiated structure of this embodiment is the ash water collection tank (3): the bottom plate (14) of the collection tank adopts an inclined structure, and the bottom end of the bottom plate is fixedly connected to the downcomer (22). The overflow weir (23) is installed below the downcomer (22). The overflow weir (23) is connected to the ash water outlet (8) on the side. The ash water outlet (8) is connected to the ash water pump (18). The overflow weir (23) stabilizes the liquid level inside the collection tank under high slag working conditions, avoiding liquid level fluctuation and airflow foaming. The downcomer (22) can guide the slag-containing ash water to flow smoothly, preventing local slag accumulation and medium splashing.

[0051] To adapt to high dust conditions, the washing device (2) in this embodiment is upgraded to a staggered structure of three-layer herringbone baffles (13) and three-layer washing water pipes (11) to extend the gas-liquid contact time; the valve group adopts a combination of washing water regulating valve (20) and washing water switching valve (21) to take into account both precise flow regulation and high-flow-rate powerful flushing; the washing water source uses a higher purity change condensate to enhance the fine ash removal effect. The ash water collection tank (3) still adopts a one-to-one assembly structure of multiple sets of collection tank riser pipes (15) and inverted U-shaped baffles (16) to ensure the gas-liquid separation accuracy under harsh conditions. The heat exchange device (4) adopts an anti-clogging staggered tower plate (17) to adapt to the heat exchange requirements of high impurity gas flow.

[0052] The specific operating process steps in this embodiment are as follows: Step 1, flash evaporation and pressure reduction: The feed black water temperature is 245℃ and the pressure is 4.2MPa. The operating pressure inside the tower is stable at 0.85MPa. The high slag content black water undergoes rapid flash evaporation and phase change. Large particles of waste slag settle rapidly and are continuously discharged from the waste slag outlet (10) to avoid slag accumulation.

[0053] Step 2, Multi-stage enhanced washing: Flash steam is rectified step by step through three layers of herringbone baffles (13), and the flow rate of condensate spray is adjusted by regulating valve and switching valve to 12-15 m³ / h. The large flow rate of high-cleanliness washing water thoroughly removes high-concentration fine ash from the gas phase.

[0054] Step 3, pressure stabilization and gas-liquid separation: Flash steam is intercepted by the riser pipe (15) and the inverted U-shaped baffle (16). The slag-containing ash water that falls back is collected by the inclined bottom plate (14), guided by the downcomer plate (22), and stabilized by the overflow weir (23). It is then discharged quantitatively from the ash water outlet (8), which completely solves the problem of secondary ash carrying and liquid level fluctuation in high slag working conditions.

[0055] Step 4, High-efficiency heat exchange: Clean flash steam rises and enters the heat exchange device (4), where it fully exchanges heat with the low-temperature ash water in a countercurrent flow, resulting in thorough waste heat recovery, complete desorption of acidic gas, and reduced equipment corrosion.

[0056] Step 5, High-frequency intelligent cleaning: Adjust the system pressure difference change percentage to 40-60%. A small amount of dust accumulation will trigger the system to automatically open the washing water switch valve (21) to instantly increase the flow rate and provide high-pressure, powerful online flushing to quickly remove scale and dust accumulation.

[0057] Implementation Results: This embodiment completely solves the pain points of traditional equipment in high-slag-content conditions, such as easy slag accumulation, unstable liquid level, and turbulent airflow, through the combination structure of inclined bottom plate, downcomer plate and overflow weir; the dual anti-clogging mechanism of multi-stage enhanced washing + powerful online cleaning completely eliminates tray blockage and flooding problems, increasing the continuous running time of the equipment by more than 40%; the use of changing condensate washing provides excellent dust removal and purification effect, and the equipment can still exchange heat stably and efficiently under harsh conditions, taking into account multiple advantages such as stable production, anti-clogging, and corrosion prevention, and is suitable for various high-impurity and harsh production scenarios.

[0058] Example 3

[0059] This embodiment is designed for the energy-saving and stable operation requirements of coal chemical plants under low load, variable load, and intermittent production. The basic structure of the equipment is the same as that in Embodiment 1. It adopts a horizontal water collection tank bottom plate (14) with no dead corners for liquid or slag accumulation. The core optimization is a dual-source adaptive switching strategy for low-temperature ash water and changing condensate. Combined with refined valve group regulation and low load differential pressure adaptation logic, it maximizes energy and water saving while ensuring that the process indicators meet the standards.

[0060] In this embodiment, the equipment is fully equipped with all core structures: the tower body (1) is internally arranged with heat exchange devices (4), ash water collection tank (3), and washing device (2); it is equipped with all process ports, including black water inlet (5), flash steam outlet (6), ash water inlet (7), ash water outlet (8), black water discharge outlet (9), and waste residue outlet (10). The ash water outlet (8) is connected to an external ash water pump (18) for stable discharge. The washing device (2) adopts a double-layer herringbone baffle (13) and a double-layer washing water pipe (11) arranged in an alternating manner. The washing water pipe (11) is evenly equipped with washing water nozzles (12). The pipeline is connected to two washing water sources, low-temperature ash water and condensate, through the washing water main pipe (19). The valve group is equipped with a washing water regulating valve (20) and a washing water switch valve (21), which can adaptively switch water sources and precisely control the flow rate according to the working conditions. The grey water collection tank (3) is equipped with a horizontal base plate (14), multiple sets of water collection tank riser pipes (15) and inverted U-shaped baffles (16) to ensure stable gas-liquid separation under low load conditions; the heat exchange device (4) adopts multi-layer staggered tower plates (17) to adapt to the demand for precise heat exchange at low flow rates; the herringbone baffle (13) is equipped with differential pressure transmitters upstream and downstream to realize automatic cleaning with differential pressure linkage.

[0061] The specific operating process steps in this embodiment are as follows: Step 1, Adaptive Low-Pressure Flash Evaporation: When the unit is running at low load, the parameters of the feed black water are reduced to a temperature of 230℃ and a pressure of 3.5MPa. Simultaneously, the flash evaporation pressure inside the tower is reduced to 0.7MPa to reduce the energy consumption of the equipment while ensuring complete flash evaporation.

[0062] Step 2, Dual-source energy-saving washing: Under normal low-load conditions, the device's self-produced low-temperature ash water is preferentially switched as the washing water source. The spray flow rate is precisely controlled at 5-7 m³ / h through the washing water regulating valve (20) to meet the dust removal requirements with minimal water consumption. When the device's water quality fluctuates or the ash water impurities exceed the standard, the system automatically switches to changing the condensate washing to ensure the quality of flash steam purification.

[0063] Step 3, stable gas-liquid separation: low-flow-rate flash vapor is gently separated through the riser pipe (15) and the inverted U-shaped baffle (16), the horizontal bottom plate is free of siltation, the ash water is steadily collected and discharged, and the working conditions inside the tower are stable.

[0064] Step 4: Precise energy-saving heat exchange: Low-flow-rate, low-temperature ash water flows from top to bottom through the staggered tower plate (17) and exchanges heat precisely in countercurrent with low-flow-rate, high-temperature flash steam, recovering waste heat as needed and avoiding energy waste caused by large-flow-rate media.

[0065] Step 5, Low-frequency intelligent cleaning: When the system pressure difference percentage exceeds 60-80% of normal operation, the spray flow rate is finely adjusted to perform low-frequency online cleaning, minimizing cleaning water and energy consumption.

[0066] Implementation Results: This embodiment relies on dual-water-source adaptive switching technology to perfectly adapt to the variable load and intermittent production conditions of the device. Compared with traditional fixed water source equipment, the overall water consumption and energy consumption are reduced by 20% to 25%. The equipment does not require shutdown or manual intervention, has a high degree of automation, and extremely low operation and maintenance costs. While ensuring that the various process indicators of flash evaporation, dust removal, and heat exchange meet the standards, it achieves energy saving and consumption reduction, green production, and has a wider range of operating conditions adaptability, with significant economic and environmental advantages.

[0067] Overall summary of the implementation examples: Based on the three sets of differentiated embodiments described above, it can be seen that this invention constructs an integrated coal gasification flash evaporation treatment equipment that can fully cover conventional full-load, high-slag harsh conditions, and low-load energy-saving conditions through modular integrated structure, adaptable water collection structure, dual-source washing system, and differential pressure linkage online self-cleaning technology. The horizontal base plate structure is suitable for conventional stable production scenarios, with a simple structure and no residual slag accumulation, ensuring long-term efficient operation of the equipment; the inclined base plate is equipped with a downcomer and overflow weir structure, which specifically solves the industry pain points of easy clogging, liquid level fluctuation, and frequent maintenance under high slag conditions, greatly improving the equipment's anti-interference ability and continuous operation capability; the dual-source adaptive switching structure can accurately adapt to variable load and intermittent production scenarios, achieving water-saving and energy-saving refined operation. Compared to traditional flash evaporation equipment, this invention integrates multiple processes in a single tower, eliminates external heat exchange equipment, and has low investment costs; multiple protections including pre-dust removal, anti-clogging tower plates, and online cleaning completely solve the problem of tower plate blockage; wastewater is self-circulated and directly and efficiently exchanged for heat, resulting in outstanding energy and water conservation effects; fully automated operation and maintenance eliminates the need for downtime, effectively extending the operating cycle of the device, while also fully analyzing acidic gases and slowing down equipment corrosion, demonstrating significant safety and environmental advantages, and possessing strong engineering practicality and industrial promotion value.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-pressure flash evaporator for coal gasification, comprising a tower body (1), characterized in that: The tower body (1) is equipped with a heat exchange device (4), a grey water collection tank (3) and a washing device (2) arranged in sequence along the axial direction from top to bottom; the tower body (1) is equipped with a black water inlet (5), a flash steam outlet (6), a grey water inlet (7), a grey water outlet (8), a black water discharge outlet (9) and a waste residue outlet (10) on the outside. The washing device (2) includes a herringbone baffle (13) and a spray system. The spray system consists of a washing water pipe (11), washing water nozzles (12) and a washing water valve group. The washing water valve group is located outside the tower body (1), and the washing water pipe (11) is connected to the washing water main pipe (19) through the washing water valve group. The washing water main pipe (19) is connected to a washing water source. The grey water collection tank (3) includes a bottom plate (14), a water collection tank air riser (15), and an inverted U-shaped baffle (16). There are several water collection tank air risers (15), and several water collection tank air risers (15) are connected above the bottom plate. An inverted U-shaped baffle (16) is provided above each layer of water collection tank air risers (15). The heat exchange device (4) is composed of multiple layers of trays (17), which are arranged alternately.

2. The high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: The black water inlet (5) is located in the area below the washing device (2), the flash steam outlet (6) is located at the center of the tower body (1), the ash water inlet (7) is located in the area above the heat exchange device (4), the ash water outlet (8) is located on the side of the ash water collection tank (3), the ash water outlet (8) is connected to the ash water pump (18), the black water discharge port (9) is located at the lower part of the outside of the tower body (1), and the waste residue outlet (10) is located at the center of the lower part of the tower body (1).

3. The high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: The washing water source is either low-temperature grey water or a modified condensate.

4. The high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: The herringbone baffle (13) and the washing water pipe (11) are both provided with several layers. The herringbone baffle (13) is provided between two adjacent layers of washing water pipe (11), and several washing water nozzles (12) are evenly provided on the side of the washing water pipe (11) near the herringbone baffle (13).

5. The high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: The washing water valve assembly adopts a washing water regulating valve (20) or a washing water on / off valve (21).

6. The high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: The bottom plate (14) of the water collection tank is a horizontal or inclined structure.

7. A high-pressure flash evaporator for coal gasification according to claim 6, characterized in that: When the bottom plate (14) of the water collection tank is a horizontal structure, the grey water outlet (8) is directly connected to the bottom plate (14) of the water collection tank, and the lower side of the pipe of the grey water outlet (8) is flush with the bottom plate (14) of the water collection tank.

8. A high-pressure flash evaporator for coal gasification according to claim 6, characterized in that: When the bottom plate (14) of the water collection tank is inclined, a downcomer (22) and an overflow weir (23) are provided between the grey water outlet (8) and the bottom plate (14) of the water collection tank. The downcomer (22) is connected to the end of the bottom plate (14) of the water collection tank, and the overflow weir (23) is located below the downcomer (22). The overflow weir (23) is connected to the grey water outlet (8).

9. A high-pressure flash evaporator for coal gasification according to claim 1, characterized in that: Differential pressure transmitters are provided upstream and downstream of the herringbone baffle (13). The differential pressure transmitters are used to automatically trigger the spray system to perform online cleaning when the differential pressure reaches a preset threshold.

10. A method for treating black water from a coal gasification high-pressure flash distillation tower, based on the coal gasification high-pressure flash distillation tower according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Flash evaporation: High-temperature and high-pressure slag-containing black water enters the tower body (1) through the black water inlet (5). The pressure drops sharply and flash evaporation occurs, forming flash steam and black water residue. S2. Washing and dust removal: Flash steam enters the washing device (2), and low-temperature ash water or alternating condensate is used as the washing water source. The direction of flash steam flow is changed by the herringbone baffle (13), and the washing water nozzle (12) sprays and washes to remove the ash and slag carried by the flash steam. S3. Gas-liquid separation: The washed flash vapor enters the ash water collection tank (3) and rises through the riser pipe of the ash water collection tank (3). Under the guidance of the inverted U-shaped baffle (16), the airflow direction is changed. The fine mist droplets and residual ash slag entrained in the flash vapor are separated by gravity and flow back to the ash water collection tank (3). S4. Direct heat exchange: The clean flash vapor after gas-liquid separation enters the heat exchange device (4) and directly contacts the low-temperature ash water entering from the ash water inlet (7) on the multi-layer tower plate (17) for heat exchange. The flash vapor after heat exchange is sent out through the flash vapor outlet (6), and the heated ash water falls into the ash water collection tank (3) and is discharged through the ash water outlet (8). S5. Online cleaning: The differential pressure is monitored in real time by differential pressure transmitters located upstream and downstream of the herringbone baffle (13). When the differential pressure reaches a preset threshold, the washing water regulating valve (20) is automatically adjusted or the washing water switch valve (21) is opened to increase the washing water flow rate and perform online rinsing on the washing device (2).

Images