Method for purifying black water from coal-water slurry gasification reactor or carbon scrubber

Abstract

The present invention discloses a method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber, comprising: introducing the black water into a descaling and softening device, adding a scale inhibitor or an acid solution to the descaling and softening device, and thoroughly mixing the black water and the agent under stirring; the black water treated by the descaling and softening device enters a filter, and the solids and liquids in the black water are separated to obtain a filter residue and a clear liquid. The present invention effectively prevents the formation of a scale layer by introducing the black water into a descaling and softening device for preliminary treatment, adding a scale inhibitor or an acid solution, and stirring and mixing. The subsequent filtration step achieves solid-liquid separation, obtaining a filter residue and a clear liquid, laying the foundation for subsequent processing and utilization, preliminarily purifying the black water, and reducing environmental pollution.

Description

Technical Field

[0001] The present invention relates to the field of black water treatment, and more particularly to a method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber. Background Art

[0002] The coal-water slurry gasification process converts coal-water slurry into synthesis gas (syngas). Coal-water slurry is a combustible liquid formed by mixing pulverized coal with water. Passing through a gasification reactor, a gaseous mixture rich in combustible gases is produced, commonly known as synthesis gas or coal gas. The wastewater discharged directly from the bottom of the gasification reactor and carbon scrubber is black in color due to the large amount of residual carbon from gasification, hence the name "black water." The temperature of black water is 220-270°C, and the pressure is 4-6.5 MPa.

[0003] Existing black water purification technologies that can be industrially applied include:

[0004] In the first step, the acid gas and water vapor in the black water are separated by flash evaporation technology. Flash evaporation is generally multi-stage, and the solids after flash evaporation remain in the liquid.

[0005] In the second step, the remaining liquid after flash evaporation is called gray water. The gray water enters the sedimentation tank, and flocculants are added or electrochemical flocculation is used to cause some particulate matter to flocculate and settle. The main function of adding flocculants to gray water is to condense solid impurities in the water into large clumps, which are convenient for subsequent filtration and precipitation, thereby improving water quality. Flocculants, through adsorption and bridging effects, condense suspended particles and colloidal substances in the water into larger flocs. These flocs are easier to separate from the water, achieving the purpose of purifying water quality. The settled flocs are returned to the coal blending for use, and the remaining liquid enters the downstream device;

[0006] In the third step, the liquid at the top of the sedimentation tank enters the ash water tank. Dispersants need to be added before entering the ash water tank. The main purpose of adding dispersants to the ash water is to prevent the aggregation and deposition of solid particles, reduce scaling and equipment corrosion. Dispersants disperse suspended matter, microcrystals and other particles in the ash water through physical or chemical effects, preventing them from aggregation and deposition, thereby inhibiting the formation of hard scale. In addition, dispersants can also form stable complexes with hard water ions such as calcium and magnesium in the ash water, reducing their concentration and further inhibiting the formation of hard scale. Part of the water after the ash water tank is heated and pressurized to enter the gasification reactor for continued use, and part enters sewage treatment; part of the ash water tank liquid is discharged, and part is heated and recycled to enter the carbon washing tower or gasification reactor.

[0007] The existing process flow is long, and the tiny solids in black water are difficult to remove. During black water treatment, equipment and pipelines are very prone to scaling, causing blockage or reduced heat exchanger efficiency. At the same time, flocculants and dispersants need to be added, which requires large investments in equipment investment and operating costs and is not conducive to maintenance. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, by directly introducing the black water into a descaling and softening device for preliminary treatment. This process does not require cumbersome steps such as multi-stage flash evaporation and flocculation in a sedimentation tank, and the process flow is short. Adding a scale inhibitor or an acid solution to the descaling and softening device and stirring and mixing it can effectively remove easily scaling substances such as calcium and magnesium in the black water and prevent the formation of a scale layer. Compared with the prior art, this method avoids the use of flocculants and dispersants, which not only reduces the cost of chemicals and equipment investment, but also reduces the secondary pollution problems that may be caused by the use of chemicals. Subsequently, solid-liquid separation can be achieved through a simple filtration step to obtain filter residue and clear liquid, which lays the foundation for subsequent treatment and utilization, preliminarily purifies the black water, and reduces pollution to the environment.

[0009] To achieve these objects and other advantages of the present invention, a method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber is provided, comprising:

[0010] Lead the black water into the descaling and softening device, add the scale inhibitor or acid solution into the descaling and softening device, and fully mix the black water and the agent under stirring;

[0011] The black water after being treated by the descaling and softening device enters the filter to separate the solid and liquid in the black water to obtain filter residue and clear liquid;

[0012] The filter residue is introduced into the filter residue tank, and the solid water in the filter residue tank is flash evaporated and then reused for coal blending, or dried to become dry residue;

[0013] After the clear liquid undergoes high-pressure flash evaporation, part of it is used as quenching water for the carbon washing tower and gasification reactor, and the other part is further subjected to low-pressure flash evaporation and vacuum flash evaporation before being used for coal slurry preparation or discharged as wastewater.

[0014] Preferably, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the filter adopts a microsphere metal powder coated filter element with a filtration accuracy of 0.1 μm and an operating pressure of 4-6.5 MPa, and separates solid particles with a particle size greater than 0.1 μm to obtain filter residue and a clear liquid with a solid content of less than 50 ppm.

[0015] Preferably, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber, the steps of subjecting the clear liquid to high-pressure flash evaporation, using a portion as quenching water for the carbon scrubber and the gasification reactor, and further subjecting the other portion to low-pressure flash evaporation or vacuum flash evaporation for use in coal slurry preparation include:

[0016] High-pressure flash evaporation: The clear liquid is placed under high-pressure flash evaporation conditions of 1.0-2.0 MPa and 150-180°C. After flash evaporation, the clear liquid is divided into two parts;

[0017] The first part of the clear liquid is directly recycled to the carbon scrubber and the quench water system of the gasification reactor;

[0018] The second part of the clear liquid is subjected to low-pressure flash evaporation and vacuum flash evaporation in sequence, and then enters the pH adjustment tank. In the pH adjustment tank, a NaOH solution with a mass concentration of 5-10% is added to the clear liquid through a static mixer to adjust the pH of the clear liquid to 6.5-7.5; the adjusted clear liquid is transported to the water supply system of the gasification reactor by a centrifugal pump and mixed with fresh water for coal slurry preparation;

[0019] Among them, an online pH meter and turbidity meter are installed at the outlet of the pH adjustment tank to monitor the pH value and turbidity of the clear liquid in real time and control the turbidity of the clear liquid to ≤10NTU. At the same time, the temperature of the recycled clear liquid is reduced to ≤40℃ through a heat exchanger.

[0020] Preferably, the method for purifying black water from the water-coal slurry gasification reactor or the carbon scrubber further comprises:

[0021] When the filter cake in the filter reaches a preset thickness, the slag discharge operation is performed, so that the filter cake and the solution attached to the filter cake and mixed in it are flushed into the filter residue tank.

[0022] Preferably, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the descaling and softening device comprises:

[0023] The shell is in the shape of a hollow cylinder, and a fluid outlet is provided at the upper portion of the shell;

[0024] a premixing chamber, which is a cylindrical body with a hollow interior and an open top, and is vertically disposed in the lower portion of the shell and spaced a preset distance from the bottom of the shell;

[0025] at least one black water inlet pipe, each black water inlet pipe being connected to the side wall of the lower portion of the premixing chamber and communicating with the interior of the premixing chamber;

[0026] at least one medicine introduction tube, each medicine introduction tube being connected to the side wall of the lower portion of the premixing chamber and communicating with the interior of the premixing chamber;

[0027] A baffle assembly comprising an outer baffle and an inner baffle arranged at intervals, wherein the main body of the outer baffle is cylindrical and fixed to the inner side wall of the shell, the inner side wall of the outer baffle and the outer side wall of the inner baffle are both provided with a wavy structure, and the crests and troughs on the outer baffle are respectively opposite to the crests and troughs on the inner baffle, the upper portion of the inner baffle is cylindrical and is located above the premixing chamber and is separated from the premixing chamber by a preset distance, and the lower portion of the inner baffle is cylindrical and covers the premixing chamber;

[0028] A stirring assembly, comprising a stirring shaft, a plurality of first stirring blades, a plurality of second stirring blades, and a plurality of third stirring blades; the stirring shaft is rotatably connected to the top and bottom of the shell, and vertically passes through the inner baffle and the premixing chamber, and is rotatably connected to the inner baffle and the premixing chamber; each first stirring blade is located in the premixing chamber, and a first stirring blade is provided above and below the inlet of the black water inlet pipe and the reagent inlet pipe, each second stirring blade is located below the premixing chamber, and each third stirring blade is located above the outer baffle and the inner baffle;

[0029] The guide assembly includes a plurality of staggered and spaced guide plates, the plurality of guide plates are respectively located on the inner side wall of the lower part of the inner baffle and the outer side wall of the premixing chamber, the guide plate on the inner baffle is in the shape of an inverted truncated cone and is spaced a preset distance from the premixing chamber, the guide plate on the premixing chamber is in the shape of a truncated cone and is spaced a preset distance from the inner baffle, the guide plate located at the top is arranged on the premixing chamber, the guide plate is provided with a plurality of circles of annular protrusions spaced along its busbar direction, each circle of protrusions is provided with at least one pair of openings, and the openings on adjacent protrusions on each guide plate are staggered; the fluid on the guide plate on the inner baffle can flow to the innermost protrusion on the guide plate below it, and the fluid on the guide plate on the premixing chamber can flow to the outermost protrusion on the guide plate below it. Preferably, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the descaling and softening device also includes:

[0030] At least one ultrasonic component is arranged at the bottom of the shell, and a probe of each ultrasonic component contacts the bottom of the shell.

[0031] Preferably, in the method for purifying black water from the water-coal slurry gasification reactor or the carbon washing tower, each reagent inlet pipe enters tangentially from the lower part of the premixing chamber and is separated from the bottom of the premixing chamber by a preset distance, and the height of each reagent inlet pipe is lower than the height of each black water inlet pipe.

[0032] Preferably, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, there are 3-6 black water inlet pipes, all of which are evenly distributed on the same circumference, and spiral swirl nozzles are used at the outlet of each black water inlet pipe.

[0033] Preferably, in the method for purifying black water from the water-coal slurry gasification reactor or the carbon washing tower, the inner baffle is connected to the premixing chamber through a plurality of first connecting rods, and is connected to the shell through a plurality of second connecting rods, the premixing chamber is connected to the shell through a plurality of third connecting rods, and each first connecting rod, each second connecting rod, and each third connecting rod is separated from the stirring assembly by a preset distance.

[0034] Preferably, in the method for purifying black water from the water-coal slurry gasification reactor or the carbon washing tower, the shell, the stirring shaft, the inner baffle, the outer baffle, the premixing chamber and each guide plate are coaxially arranged, the angle between the busbar of each guide plate and the vertical direction is 30-45 degrees, and the cross-section of each circle of protrusions is an upwardly arched arc.

[0035] The present invention has at least the following beneficial effects:

[0036] The key achievement of the present invention, which eliminates solids from the medium in the gasification reactor or downstream equipment of the carbon scrubber, has brought a series of positive impacts. Firstly, it reduces internal equipment wear and tear caused by friction and wear from solid particles, significantly reducing equipment maintenance frequency, thereby extending the equipment's service life and reducing the high investment costs associated with equipment replacement and repair. Secondly, the absence of solids in the medium makes the operation process smoother and more stable, easing the operator's workload and reducing the risk of accidents caused by improper operation. This significantly enhances the reliability of the entire system, ensures production continuity, and brings more stable economic benefits to the enterprise.

[0037] The present invention uses black water from the outlet of a gasification reactor or carbon scrubber as raw material. This raw material selection not only fully utilizes the properties of black water but also significantly improves purification efficiency and effectiveness. The specific composition and state of black water enhances the purification process, rapidly separating impurities and harmful substances. Furthermore, this raw material provides a suitable operating environment for the filter, effectively reducing clogging and contamination, extending the filter's service life, ensuring long-term stable operation, and ensuring consistently high quality of the purified black water.

[0038] The descaling and softening device provided by the present invention can operate stably in high-temperature environments. By adding reagents and achieving uniform mixing with the help of an efficient mixing device, it can effectively prevent the formation of black scale. This feature avoids equipment failure and energy waste caused by scaling, ensuring efficient operation of the equipment. Furthermore, the high-precision filter also operates at high temperatures, avoiding the complex process of cooling and then heating in traditional processes, directly reducing significant energy losses. This not only reduces energy costs but also reduces carbon emissions caused by energy consumption, in line with the development concept of green environmental protection.

[0039] The present invention uses a filter with a filtration accuracy of 0.1μm, which can effectively intercept tiny solid impurities, so that the solid content in the purified black water is ≦50ppm, thereby improving the black water purification quality, meeting higher use requirements, and reducing the clogging and wear of subsequent equipment. The online cleaning and regeneration system equipped with the high-precision filter of the present invention is the key to its performance enhancement. The system can monitor the operating status of the filter in real time, and automatically start the cleaning and regeneration program when it is found that the inner wall of the filter or the filter element has a tendency to scale. In this way, it can not only effectively prevent the influence of scaling on the filtration effect, but also significantly extend the service life of the filter element and reduce the cost of filter element replacement. At the same time, it ensures that the filter is always in an efficient operating state, ensures that the purification quality of black water is stable and reliable, and reduces the secondary processing costs caused by poor filtration effect.

[0040] The filter residue after the filter of the present invention can be directly added to the water-coal slurry for coal blending after flash evaporation and concentration, achieving resource recycling. Unreacted coal powder contained in the filter residue can be reused, improving the conversion rate of coal powder and reducing the waste of coal resources. At the same time, the cost and difficulty of filter residue treatment are reduced, and environmental pollution is reduced. Furthermore, the clean water purified by the black water filter can be directly reused in a high-pressure flash evaporator as quenching water for the carbon scrubber and gasification reactor, improving water resource utilization, reducing fresh water consumption, and achieving the goal of energy conservation and emission reduction.

[0041] The black water purified by the present invention does not require the addition of flocculants and dispersants, which directly reduces the procurement cost of reagents. This also avoids water contamination by reagents, reducing the difficulty and cost of subsequent sewage treatment. Because the discharged sewage does not contain solids, it greatly simplifies the subsequent sewage treatment process and reduces the investment and operating costs of sewage treatment equipment. This not only saves companies a significant amount of money but also reduces environmental pollution, providing significant environmental benefits and helping companies achieve sustainable development.

[0042] This innovative process eliminates the cumbersome steps of traditional multi-stage flash evaporation and flocculation in a sedimentation tank. Instead, it directs blackwater to a descaling and softening unit for initial treatment, streamlining the process and reducing equipment investment and floor space. Furthermore, the descaling and softening unit, filter, and other components work together to form a highly efficient purification system. These interlinked processes enhance overall treatment efficiency and effectiveness, ultimately optimizing and upgrading the process.

[0043] The descaling and softening device of this invention features a sophisticated internal structure. The premixing chamber, baffle assembly, stirring assembly, and diversion assembly work together to achieve a mixing uniformity of over 95% between blackwater and the reagent, significantly improving wastewater treatment efficiency. Tangential entry of the reagent inlet pipe and the use of a spiral swirl nozzle in the blackwater inlet pipe further enhance the mixing effect. Furthermore, the components are securely connected. The inner baffle, premixing chamber, and housing are connected by connecting rods and maintained at an appropriate distance from the stirring assembly. The coaxial arrangement of the components ensures a stable layout and reliable operation.

[0044] The high-pressure flash evaporation (1.0-2.0MPa) of the present invention directly reuses the quenching water; the low-pressure + vacuum flash evaporation combined with pH adjustment (6.5-7.5) and cooling (≤40°C) can increase the clear liquid reuse rate to 90%, save 30%-50% of water, and reduce carbon emissions by 40%.

[0045] The present invention reduces wastewater discharge by 60%, and the filter residue is directly reused for coal blending, resulting in efficient resource circulation; the comprehensive energy consumption and cost are reduced by 25%, meeting the requirements of green production.

[0046] The present invention solves the technical problems of high moisture content of filter residue and low clear liquid reuse rate in water-coal slurry gasification black water treatment by adding scale inhibitor or acid solution to the descaling softener, filtering with high-precision filter and innovating the clear liquid reuse process.

[0047] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a process flow chart of a method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber according to one embodiment of the present invention;

[0049] Figure 2 This is a process flow diagram of a method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber according to one embodiment of the present invention;

[0050] Figure 3 is a structural schematic diagram of a descaling and softening device according to an embodiment of the present invention;

[0051] Figure 4 is a schematic structural diagram of a guide plate according to an embodiment of the present invention;

[0052] Among them, the figure markings are as follows: descaling and softening device-1; filter-2; filter residue tank-3; flash tank-4; dryer-5; high-pressure flash tank-6; low-pressure flash tank-7; vacuum flash tank-8; shell-101; fluid outlet-102; premixing chamber-103; black water inlet pipe-104; reagent inlet pipe-105; outer baffle-106; inner baffle-107; stirring shaft-108; first stirring blade-109; second stirring blade-110; third stirring blade-111; guide plate-112; protrusion-113; opening-114; ultrasonic component-115; first connecting rod-116; second connecting rod-117; third connecting rod-118. DETAILED DESCRIPTION

[0053] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0054] It should be noted that, in the description of the present invention, the terms "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] like Figure 1 and Figure 2 As shown, the present invention provides a method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber, comprising:

[0056] The black water is introduced into the descaling and softening device 1, and a scale inhibitor or acid solution is added into the descaling and softening device 1 so that the black water and the agent are fully mixed under stirring;

[0057] The black water after being treated by the descaling and softening device 1 enters the filter 2 to separate the solid and liquid in the black water, and obtain filter residue and clear liquid. During the gasification process, after the coal slurry undergoes combustion and cracking reactions in the combustion chamber, a large amount of carbon dioxide is generated in the process gas to form HCO 3- At high temperatures, HCO 3- Will decompose into CO3 2- , and Ca in black water 2+ Mg 2+ The plasma combines to form carbonates such as CaCO3 and MgCO3, which adhere to the walls and pipes, forming scale. Descaling and softening device 1 primarily adjusts the pH of the black water and adds scale inhibitors and dispersants to ensure that the black water entering filter 2 is not prone to scaling.

[0058] The black water discharged from the gasification reactor or carbon washing tower is used as raw material and enters the high-precision filter 2 through the descaling and softening device 1. At this position, the black water temperature is ≥200℃ and the pressure is ≥3.5MPa. The grease at high temperature is in liquid state with low viscosity. The liquid can easily pass through the filter element, and the solids are intercepted and separated.

[0059] The black water produced by the coal-water slurry gasification reactor or carbon scrubber has a high temperature and pressure and contains a large amount of impurities. In practical applications, the black water is first introduced into the descaling and softening device 1 through a pipeline. The descaling and softening device 1 is typically a closed container equipped with an internal stirring device. An appropriate amount of scale inhibitor or acid solution is added to the descaling and softening device 1. The scale inhibitor can be a common organic phosphonate scale inhibitor, and the acid solution can be dilute hydrochloric acid or dilute sulfuric acid. The stirring device is activated to thoroughly mix the black water and the agent. The stirring time and speed are adjusted according to the flow rate and properties of the black water. Generally, the stirring time is 10-30 minutes and the stirring speed is 100-300 rpm. After being treated in the descaling and softening device 1, the black water flows through a pipeline into the filter 2. The filter 2 can be a high-precision filter cartridge. When the black water passes through the filter cartridge, solid impurities are trapped on the filter surface, while the liquid passes through the filter cartridge, achieving solid-liquid separation and producing a filter residue and a clear liquid.

[0060] This solution effectively removes hardness components from the black water and prevents scale formation by introducing black water into a descaling and softening device 1 for preliminary treatment. A scale inhibitor or acid solution is then added and stirred to effectively remove the hardness components in the black water. The subsequent filtration step achieves solid-liquid separation, yielding a filter residue and a clear liquid, which paves the way for subsequent processing and utilization, preliminarily purifies the black water, and reduces environmental pollution.

[0061] The filter residue is introduced into the filter residue tank 3. The solid water in the filter residue tank 3 is flashed in the flash tank 4 and then reused for coal blending, or dried in the dryer 5 to become dry residue. Reusing coal blending means that during the black water treatment process of the water-coal slurry gasification reactor or the carbon washing tower, the solid water in the filter residue tank 3 can be returned to the coal blending process for reuse after flash evaporation. In the water-coal slurry preparation process, coal powder and water need to be mixed in a certain proportion to form water-coal slurry. These solid-containing filter residues contain solid substances such as unreacted coal powder, which have certain calorific value and utilization value. Flashing the solid water in the filter residue tank 3 and then reusing it for coal blending can, on the one hand, increase the conversion rate of unreacted coal powder and make more full use of coal resources; on the other hand, it can reduce raw material costs and reduce the use of new coal powder. At the same time, it also reduces the amount of filter residue to be processed, reduces the impact on the environment, and to a certain extent achieves resource recycling and energy conservation and emission reduction.

[0062] After the clear liquid passes through high-pressure flash evaporation in the high-pressure flash tank 6, a part of it is used as quenching water for the carbon washing tower and the gasification reactor, and the other part continues to pass through low-pressure flash evaporation in the low-pressure flash tank 7 and vacuum flash evaporation in the vacuum flash tank 8, and is used for coal slurry preparation or discharged as sewage.

[0063] The residue obtained from the filtration of filter 2 is piped into a residue tank 3. Residue tank 3 is a storage container for temporary storage of the residue. The solid water in residue tank 3 can be flash-evaporated in a flash tank 4. Flash evaporation is a process that uses a sudden drop in pressure to rapidly evaporate some of the water in the solid water. The steam after flash evaporation can be recycled, and the solid water can be reused for coal blending, improving coal utilization. Alternatively, the solid water after flash evaporation can be dried in a dryer 5 to form dry residue for easier storage and transportation.

[0064] The clear liquid obtained from filter 2 is introduced into high-pressure flash tank 6 for high-pressure flash evaporation. A portion of the clear liquid after high-pressure flash evaporation is used as quench water for the carbon scrubber and gasification reactor, providing cooling and washing. The remaining portion undergoes low-pressure and vacuum flash evaporation to further remove impurities and moisture, ultimately being used for coal slurry preparation or discharged as wastewater.

[0065] This solution provides for the rational subsequent treatment and utilization of the filter residue and clear liquid obtained from filter 2. The solid-water content in filter residue tank 3 is flash-evaporated and then reused for coal blending or dried into dry residue, achieving resource recycling and reducing production costs. The clear liquid undergoes high-pressure flash evaporation, with some used as quenching water and some further processed for coal slurry preparation or discharge, improving water resource utilization and reducing waste emissions.

[0066] In another embodiment, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the filter uses a microsphere metal powder coated filter element with a filtration accuracy of 0.1 μm and an operating pressure of 4-6.5 MPa, separating solid particles with a particle size greater than 0.1 μm to obtain filter residue and a clear liquid with a solid content less than 50 ppm.

[0067] When using filter 2 with a filtration accuracy of 0.1μm, it is necessary to select appropriate filter element materials and structures. This solution selects a coated sintered filter element, which is not only corrosion-resistant and high-temperature resistant, but also has high filtration accuracy, and the solid content in the purified black water is ≦50ppm. When installing filter 2, make sure that the filter element is installed correctly and sealed well to avoid black water leakage. When black water enters filter 2, since the filtration accuracy of the filter element is 0.1μm, it can effectively intercept solid particles with a diameter greater than or equal to 0.1μm, greatly reducing the solid content in the purified clear liquid. As the filtration proceeds, filter cake will gradually accumulate on the surface of the filter element, and the filter element needs to be cleaned or replaced regularly to ensure the filtration effect.

[0068] This solution uses a filter 2 with a filtration accuracy of 0.1μm, which can effectively remove smaller impurities in the black water, improve the filtration effect, make the purified black water higher in quality, meet higher usage requirements, and also reduce the clogging and wear of subsequent equipment.

[0069] In another embodiment, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber, the steps of subjecting the clear liquid to high-pressure flash evaporation, using a portion as quenching water for the carbon scrubber and the gasification reactor, and further subjecting the remaining portion to low-pressure flash evaporation or vacuum flash evaporation for use in coal slurry preparation include:

[0070] High-pressure flash evaporation: The clear liquid is placed under high-pressure flash evaporation conditions of 1.0-2.0 MPa and 150-180°C. After flash evaporation, the clear liquid is divided into two parts;

[0071] The first part of the clear liquid is directly recycled to the carbon scrubber and the quench water system of the gasification reactor;

[0072] The second part of the clear liquid is subjected to low-pressure flash evaporation and vacuum flash evaporation in sequence, and then enters the pH adjustment tank. In the pH adjustment tank, a NaOH solution with a mass concentration of 5-10% is added to the clear liquid through a static mixer to adjust the pH of the clear liquid to 6.5-7.5; the adjusted clear liquid is transported to the water supply system of the gasification reactor by a centrifugal pump and mixed with fresh water for coal slurry preparation;

[0073] An online pH meter and turbidity meter are installed at the outlet of the pH adjustment tank to monitor the pH and turbidity of the clear liquid in real time, maintaining the clear liquid turbidity at ≤10 NTU. Simultaneously, a heat exchanger cools the reused clear liquid to ≤40°C. High-pressure flash evaporation (1.0-2.0 MPa, 150-180°C) fully utilizes the clear liquid's residual heat and pressure. The separated first portion of clear liquid is directly reused as quench water, reducing fresh water consumption and heat loss. The second portion of clear liquid is gradually recycled through low-pressure and vacuum flash evaporation, reducing overall energy consumption by approximately 35%, achieving efficient cascaded energy utilization.

[0074] NaOH solution (5-10% concentration) is added through a static mixer to precisely adjust the pH of the clear liquid to 6.5-7.5, neutralizing residual acidic substances. This prevents corrosion of the carbon scrubber, gasification reactor, and pipelines by the recycled water, thereby extending equipment life. Simultaneously, online pH meters and turbidity meters monitor the clear liquid in real time, ensuring turbidity ≤10 NTU and stable pH, guaranteeing safe and reliable recycled water quality.

[0075] The regulated clear liquid is mixed with fresh water for coal slurry preparation, increasing the reuse rate to over 90% and reducing fresh water demand by 30-50%. Trace minerals in the clear liquid also improve the fluidity of the coal slurry and enhance gasification efficiency, achieving wastewater resource utilization and process optimization.

[0076] Using a heat exchanger to reduce the temperature of the recycled clear liquid to ≤40°C prevents thermal shock from high-temperature water on the coal slurry preparation system, reduces equipment thermal stress, and improves operational safety. Furthermore, the low-temperature clear liquid mixes more evenly with fresh water, ensuring a stable coal slurry ratio.

[0077] The multi-stage flash evaporation process reduces wastewater discharge by over 60%. Combined with a high percentage of reuse, this significantly reduces wastewater treatment load and chemical consumption. Furthermore, heat recovery and water conservation measures reduce overall operating costs by approximately 25%, delivering both environmental and economic benefits.

[0078] The prior art does not disclose the precise adjustment of the pH value (6.5-7.5) of the clear liquid before reuse. This application uses this step to avoid corrosion of the equipment by the recycled water.

[0079] The existing technology focuses on the initial solid-liquid separation of black water, while this application solves the problems of high moisture content of filter residue, strong scaling of clear liquid and low reuse rate in traditional processes through a full process design of descaling-filtration-reuse.

[0080] The clear liquid reuse rate has increased from 50% in traditional processes to 90%, the energy consumption of filter residue incineration has been reduced by 40%, and the equipment scaling cycle has been extended by more than 3 times.

[0081] In another embodiment, the method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber further comprises:

[0082] When the filter cake in the filter 2 reaches a preset thickness, a slag discharge operation is performed to flush the filter cake and the solution adhering to and mixed in the filter cake into the filter residue tank 3 .

[0083] During the operation of filter 2, the filter cake thickness must be monitored in real time. This can be done indirectly using devices such as pressure sensors or liquid level sensors. When the filter cake reaches a preset thickness, the slag discharge operation is initiated. This slag discharge operation can be performed using a backwash method. Backwashing involves passing a reverse flow of water through filter 2, flushing the filter cake, along with any solution adhering to the filter cake and entrained therein, into the filter cake tank 3. After the slag discharge operation is completed, filter 2 can resume normal operation.

[0084] In another embodiment, in the method for purifying black water from the water-coal slurry gasification reactor or carbon washing tower, Figure 3 and Figure 4 As shown, the descaling and softening device 1 comprises:

[0085] The housing 101 is a hollow cylindrical body, and a fluid outlet 102 is provided at the upper portion of the housing 101;

[0086] The premixing chamber 103 is a cylindrical body with a hollow interior and an open top, and is vertically disposed in the lower portion of the housing 101 and spaced a predetermined distance from the bottom of the housing 101;

[0087] At least one black water inlet pipe 104, each black water inlet pipe 104 is connected to the side wall of the lower portion of the premixing chamber 103 and communicates with the interior of the premixing chamber 103;

[0088] At least one medicine introduction tube 105, each medicine introduction tube 105 is connected to the side wall of the lower portion of the premixing chamber 103 and communicates with the interior of the premixing chamber 103;

[0089] A baffle assembly includes an outer baffle 106 and an inner baffle 107 that are spaced apart. The outer baffle 106 has a cylindrical body and is fixed to the inner sidewall of the housing 101. The inner sidewall of the outer baffle 106 and the outer sidewall of the inner baffle 107 are both provided with a wavy structure, and the crests and troughs on the outer baffle 106 are respectively opposite to the crests and troughs on the inner baffle 107. The upper portion of the inner baffle 107 is cylindrical and is located above the premixing chamber 103 and is separated from the premixing chamber 103 by a preset distance. The lower portion of the inner baffle 107 is cylindrical and covers the outside of the premixing chamber 103.

[0090] A stirring assembly, comprising a stirring shaft 108, a plurality of first stirring blades 109, a plurality of second stirring blades 110, and a plurality of third stirring blades 111; the stirring shaft 108 is rotatably connected to the top and bottom of the housing 101, and vertically passes through the inner baffle 107 and the premixing chamber 103, and is rotatably connected to the inner baffle 107 and the premixing chamber 103; each first stirring blade 109 is located in the premixing chamber 103, and a first stirring blade 109 is provided above and below the entrance of the black water inlet pipe 104 and the reagent inlet pipe 105, each second stirring blade 110 is located below the premixing chamber 103, and each third stirring blade 111 is located above the outer baffle 106 and the inner baffle 107;

[0091] The guide assembly includes a plurality of staggered and spaced guide plates 112, which are respectively located on the inner side wall of the lower part of the inner baffle 107 and the outer side wall of the premixing chamber 103. The guide plate 112 on the inner baffle 107 is in the shape of an inverted truncated cone and is separated from the premixing chamber 103 by a preset distance. The guide plate 112 on the premixing chamber 103 is in the shape of a truncated cone and is separated from the inner baffle 107 by a preset distance. The guide plate 112 located at the top is arranged on the premixing chamber 103, and a plurality of circles of annular protrusions 113 are spaced along the busbar direction on the guide plate 112, and each circle of protrusions 113 is provided with at least one pair of openings 114, and the openings 114 on adjacent protrusions 113 on each guide plate 112 are staggered. The fluid on the guide plate 112 on the inner baffle 107 can flow into the innermost protrusion on the guide plate 112 below it. The fluid on the guide plate 112 on the premixing chamber 103 can flow outside the outermost protrusion on the guide plate 112 below it.

[0092] The shell 101 of the descaling and softening device 1 is hollow and cylindrical, made of stainless steel for strength and corrosion resistance. A fluid outlet 102 is located at the top of the shell 101 for discharging treated blackwater. A cylindrical premixing chamber 103 is vertically positioned within the lower portion of the shell 101, spaced a certain distance from the bottom of the shell 101, providing space for initial mixing of the blackwater and the reagent. Both the blackwater inlet pipe 104 and the reagent inlet pipe 105 are connected to the lower sidewall of the premixing chamber 103, allowing for thorough mixing of the blackwater and the reagent within the premixing chamber 103. The outer baffle 106 of the baffle assembly is cylindrical and fixed to the inner sidewall of the shell 101. The wavy structure on the inner sidewall redirects the fluid flow and enhances mixing. The inner baffle 107, with its upper portion positioned above the premixing chamber 103 and its lower portion positioned outside the premixing chamber 103, guides the fluid flow. The stirring shaft 108 of the stirring assembly is rotatably connected to the top and bottom of the shell 101 and is driven to rotate by a motor. The first stirring blade 109 is located in the premixing chamber 103, and is arranged above and below the entrance of the black water inlet pipe 104 and the drug inlet pipe 105, so as to fully stir the black water and drug in the premixing chamber 103. The second stirring blade 110 is located below the premixing chamber 103 to further stir the mixed liquid. The third stirring blade 111 is located above the outer baffle 106 and the inner baffle 107 to promote mixing of the fluid in the baffle assembly. The multiple guide plates 112 of the guide assembly are staggered on the lower inner wall of the inner baffle 107 and the outer wall of the premixing chamber 103. The guide plate 112 on the inner baffle 107 is in an inverted frustum shape, and the guide plate 112 on the premixing chamber 103 is in a frustum shape. The annular protrusion 113 and opening 114 on the guide plate 112 can change the flow path of the fluid and increase the mixing and reaction time.

[0093] The operation method of the descaling and softening device 1 is as follows:

[0094] After starting the equipment, black water enters the premixing chamber 103 through the black water inlet pipe 104, and the reagent enters the premixing chamber 103 through the reagent inlet pipe 105. Since both enter from the side wall of the premixing chamber 103 at the bottom, the black water and the reagent quickly meet in the premixing chamber 103, forming an initial flow field that is conducive to mixing.

[0095] At this point, the first stirring blades 109 located within the premixing chamber 103, above and below the inlets of the black water inlet pipe 104 and the reagent inlet pipe 105, begin to operate. Driven by the stirring shaft 108, the first stirring blades 109 rotate at high speed, initially stirring and mixing the black water and reagent, achieving initial contact and fusion between the two, laying the foundation for subsequent in-depth mixing. This initial mixing method is highly efficient, greatly improving initial mixing efficiency and overall mixing uniformity, laying a solid foundation for high-quality mixing in subsequent processes.

[0096] The mixed fluid flows downward from the top of the premixing chamber 103 and passes through the staggered truncated cone-shaped guide plates 112. These guide plates 112 are provided with multiple circles of annular protrusions 113, and the openings 114 on the adjacent protrusions 113 on each guide plate 112 are staggered. When the fluid flows through the guide plate 112, under the action of the annular protrusions 113 and the openings 114, the flow direction and flow rate of the fluid are constantly changing, forming a complex turbulent flow field. The fluids in different flow layers intersperse and collide with each other, further promoting mixing, effectively increasing the degree of mixing between the fluids, improving the mixing effect, making the mixing more sufficient and uniform, and providing a better quality base fluid for subsequent stirring and mixing steps.

[0097] Next, the fluid reaches the second stirring blade 110. Located below the premixing chamber 103, the second stirring blade 110 vigorously stirs the fluid, further breaking up large clumps and enhancing the mixing effect. This stage further refines the initially mixed fluid, allowing previously incompletely blended components to be more evenly distributed, significantly improving the mixing quality.

[0098] The fluid, stirred by the second stirring blades 110, then enters the area between the outer baffles 106 and the inner baffles 107. The wavy structures on these baffles 106 and 107 are effective. As the fluid passes through these baffles, it is blocked and guided by the wavy structures, creating strong turbulence. This further enhances the mixing effect and evenly disperses the black water and reagent throughout the fluid. This step greatly enhances the mixing of the fluids, bringing the mixture closer to the final high-quality standards and ensuring that the outflowing mixed fluid is more uniform in composition and properties.

[0099] Next, the third stirring blade 111, located above the outer and inner baffles 106, 107, begins operation. This blade performs a final stirring and fine-tuning of the fluid after passing through the wavy structures of the outer and inner baffles 106, 107. This further ensures the uniformity of the mixed fluid, ensuring more consistent composition and properties across all components of the mixed fluid, and ensuring the stability of the resulting mixed fluid. This final stirring step consolidates and optimizes the results of the previous multi-step mixing process, ensuring that the mixed fluid fully meets the requirements of use.

[0100] Finally, the mixed fluid flows out from the fluid outlet 102 located at the upper portion of the housing 101 and enters the subsequent sewage treatment process.

[0101] After actual operational testing, the descaling and softening device 1 of the present invention achieves efficient mixing of blackwater and chemicals, with a mixing uniformity exceeding 95%, significantly improving wastewater treatment effectiveness. The seamless integration of the entire process not only improves mixing efficiency but also reduces energy consumption, equipment maintenance workload, and operating costs, resulting in significant economic benefits and practical value. Compared to traditional mixing devices, the descaling and softening device 1 demonstrates significant advantages in mixing quality, energy utilization, and equipment maintenance, providing a superior solution for liquid mixing needs in related fields.

[0102] In another embodiment, in the method for purifying black water from a coal-water slurry gasification reactor or a carbon washing tower, the descaling and softening device 1 further comprises:

[0103] At least one ultrasonic component 115 is disposed at the bottom of the housing 101 , and a probe of each ultrasonic component 115 contacts the bottom of the housing 101 .

[0104] The operation method of the descaling and softening device 1 is as follows:

[0105] After starting the equipment, black water enters the premixing chamber 103 through the black water inlet pipe 104, and the reagent enters the premixing chamber 103 through the reagent inlet pipe 105. Since both enter from the side wall of the premixing chamber 103 at the bottom, the black water and the reagent quickly meet in the premixing chamber 103, forming an initial flow field that is conducive to mixing.

[0106] At this time, the first stirring blade 109 located in the premixing chamber 103, above and below the entrances of the black water inlet pipe 104 and the drug inlet pipe 105, starts to work. Driven by the stirring shaft 108, the first stirring blade 109 rotates at high speed to preliminarily stir and mix the black water and the drug, so that the two are initially in contact and fused. At the same time, the ultrasonic component 115 set inside the premixing chamber 103 starts to emit ultrasonic waves. The high-frequency vibration of the ultrasonic waves acts on the black water and the drug, accelerating the movement between molecules, prompting the two to mix more quickly, and laying a solid foundation for subsequent deep mixing. This initial mixing method is highly efficient, greatly improving the initial efficiency of mixing, helping to improve the overall mixing uniformity, and laying a solid foundation for high-quality mixing in subsequent processes.

[0107] The mixed fluid flows downward from the top of the premixing chamber 103 and passes through the staggered truncated cone-shaped guide plates 112. These guide plates 112 are provided with multiple circles of annular protrusions 113, and the openings 114 on the adjacent protrusions 113 on each guide plate 112 are staggered. When the fluid flows through the guide plate 112, under the action of the annular protrusions 113 and the openings 114, the flow direction and flow rate of the fluid are constantly changing, forming a complex turbulent flow field. The fluids in different flow layers intersperse and collide with each other, further promoting mixing. At the same time, the ultrasonic component 115 installed near the guide plate 112 continuously emits ultrasonic waves. The energy of the ultrasonic waves further enhances the turbulent effect of the fluid, effectively increases the contact area and mixing degree between the fluids, improves the mixing effect, makes the mixing more sufficient and uniform, and provides a better quality base fluid for subsequent stirring and mixing steps.

[0108] Next, the fluid comes to the second stirring blade 110. The second stirring blade 110 is located below the premixing chamber 103, and it vigorously stirs the fluid to further break up large fluid clumps. At the same time, the ultrasonic component 115 located at the bottom of the shell 101 emits high-frequency ultrasonic waves. The energy of the ultrasonic waves acts on the fluid, causing the tiny particles and molecules in the fluid to produce high-frequency vibrations, which cooperate with the stirring action of the second stirring blade 110 to promote mixing and achieve a more refined mixing effect. This stage can further refine the mixing of the fluids that were initially mixed in the early stage, allowing the components that were not fully integrated to be more evenly distributed, significantly improving the quality of the mixing.

[0109] Subsequently, the fluid after being stirred by the second stirring blade 110 and subjected to ultrasonic action enters the area between the outer baffle 106 and the inner baffle 107. The wavy structure on the outer baffle 106 and the inner baffle 107 plays a role, and when the fluid passes through the outer baffle 106 and the inner baffle 107, it is blocked and guided by the wavy structure, forming a strong turbulence. At this time, the ultrasonic component 115 arranged in the baffle area continues to work, and the synergistic effect of ultrasonic waves and turbulence further enhances the mixing effect, making the black water and the agent more evenly dispersed in the fluid. This link greatly enhances the degree of mixing of the fluid, allowing the mixing to approach the final high quality standard, and ensuring that the outflowing mixed fluid is more uniform in composition and properties.

[0110] Afterwards, the third stirring blade 111 located above the outer baffle 106 and the inner baffle 107 starts to work. The third stirring blade 111 performs the final stirring and fine-tuning on the fluid after passing through the baffle to further ensure the uniformity of the mixed fluid. At the same time, the corresponding ultrasonic component 115 emits ultrasonic waves to assist the third stirring blade 111 to make the composition and properties of the mixed fluid more consistent in each part, ensuring the stability of the quality of the mixed fluid that finally flows out. The final stirring and ultrasonic auxiliary links consolidate and optimize the results of the previous multi-step mixing, so that the mixed fluid fully meets the use requirements.

[0111] Finally, the mixed fluid flows out from the fluid outlet 102 located at the upper portion of the housing 101 and enters the subsequent sewage treatment process.

[0112] In another embodiment, in the method for purifying black water from the water-coal slurry gasification reactor or the carbon washing tower, each reagent inlet pipe 105 enters tangentially from the lower part of the premixing chamber 103 and is separated from the bottom of the premixing chamber 103 by a preset distance, and the height of each reagent inlet pipe 105 is lower than the height of each black water inlet pipe 104.

[0113] Each reagent inlet pipe 105 enters tangentially from the bottom of the premixing chamber 103, spaced a certain distance from the bottom of the premixing chamber 103, and is lower in height than each black water inlet pipe 104. This design allows the reagent to form a tangential flow upon entering the premixing chamber 103, forming a swirling flow with the black water entering from above, enhancing the mixing effect between the reagent and black water. The diameter and flow rate of the reagent inlet pipe 105 are appropriately designed based on the black water flow rate and the dosage of the reagent to ensure that the reagent is evenly dispersed in the black water.

[0114] Each reagent inlet pipe 105 enters tangentially from the lower part of the premixing chamber 103 and is lower than the black water inlet pipe 104, so that the reagent can be better mixed with the black water, improving the mixing effect and ensuring the uniform distribution of the reagent in the black water, thereby improving the descaling and softening effect.

[0115] In another embodiment, in the black water purification method of the water-coal slurry gasification reactor or carbon washing tower, there are 3-6 black water inlet pipes 104, all of which are evenly distributed on the same circumference, and spiral swirl nozzles are used at the outlet of each black water inlet pipe 104.

[0116] Three to six black water inlet pipes 104 are evenly distributed around the same circumference. Each black water inlet pipe 104 features a spiral swirl nozzle at its outlet. As the black water passes through the spiral swirl nozzle, the resulting spiral swirl aligns with the rotational direction of the stirring assembly within the premixing chamber 103, allowing the black water to better blend into the flow field created by the stirring. This improves the mixing efficiency of the black water and reagent, providing optimal conditions for subsequent descaling and softening reactions.

[0117] In another embodiment, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the inner baffle 107 is connected to the premixing chamber 103 through multiple first connecting rods 116, and is connected to the shell 101 through multiple second connecting rods 117. The premixing chamber 103 is connected to the shell 101 through multiple third connecting rods 118, and each first connecting rod 116, each second connecting rod 117, and each third connecting rod 118 is separated from the stirring assembly by a preset distance.

[0118] The inner baffle 107 and the premixing chamber 103 are stably connected to the shell 101 through connecting rods, and each connecting rod is separated from the stirring assembly by a preset distance, which ensures the stable layout and operation of each component in the descaling and softening device 1, avoids mutual interference between components, and improves the stability and reliability of the equipment.

[0119] In another embodiment, in the method for purifying black water from a water-coal slurry gasification reactor or a carbon washing tower, the shell 101, the stirring shaft 108, the inner baffle 107, the outer baffle 106, the premixing chamber 103 and each guide plate 112 are coaxially arranged, and the angle between the busbar of each guide plate 112 and the vertical direction is 30-45 degrees, and the cross-section of each circle of protrusions 113 is an upwardly arched arc.

[0120] The shell 101, the stirring shaft 108, the inner baffle 107 and other components are coaxially arranged, the angle between the busbar of the guide plate 112 and the vertical direction is 30-45 degrees, and the cross section of the protrusion 113 is an upwardly arched arc, which optimizes the structure of the guide plate 112, makes the flow of the fluid in the descaling and softening device 1 more reasonable, promotes mixing and reaction, and improves the efficiency of descaling and softening.

[0121] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber, characterized in that: include: Lead the black water into the descaling and softening device, add the scale inhibitor or acid solution into the descaling and softening device, and fully mix the black water and the agent under stirring; The black water after being treated by the descaling and softening device enters the filter to separate the solid and liquid in the black water to obtain filter residue and clear liquid; The filter residue is introduced into the filter residue tank, and the solid water in the filter residue tank is flash evaporated and then reused for coal blending, or dried to become dry residue; After the clear liquid undergoes high-pressure flash evaporation, part of it is used as quenching water for the carbon washing tower and gasification reactor, and the other part is further subjected to low-pressure flash evaporation and vacuum flash evaporation and used for coal slurry preparation or discharged as wastewater; The filter adopts a microsphere metal powder coated filter element with a filtration accuracy of 0.1μm and an operating pressure of 4-6.5MPa, and separates solid particles with a particle size greater than 0.1μm to obtain filter residue and a clear liquid with a solid content of less than 50ppm.

2. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 1, wherein: After the clear liquid is subjected to high-pressure flash evaporation, a portion is used as quenching water for the carbon scrubber and gasification reactor, and the other portion is further subjected to low-pressure flash evaporation and vacuum flash evaporation, and then used for coal slurry preparation. The steps include: High-pressure flash evaporation: The clear liquid is placed under high-pressure flash evaporation conditions of 1.0-2.0 MPa and 150-180°C. After flash evaporation, the clear liquid is divided into two parts; The first part of the clear liquid is directly recycled to the carbon scrubber and the quench water system of the gasification reactor; The second part of the clear liquid is subjected to low-pressure flash evaporation and vacuum flash evaporation in sequence, and then enters the pH adjustment tank. In the pH adjustment tank, a NaOH solution with a mass concentration of 5-10% is added to the clear liquid through a static mixer to adjust the pH of the clear liquid to 6.5-7.5; the adjusted clear liquid is transported to the water supply system of the gasification reactor by a centrifugal pump and mixed with fresh water for coal slurry preparation; Among them, an online pH meter and turbidity meter are installed at the outlet of the pH adjustment tank to monitor the pH value and turbidity of the clear liquid in real time and control the turbidity of the clear liquid to ≤10NTU. At the same time, the temperature of the recycled clear liquid is reduced to ≤40℃ through a heat exchanger.

3. The method for purifying black water from a water-coal slurry gasification reactor or a carbon scrubber according to claim 1, wherein: Also includes: When the filter cake in the filter reaches a preset thickness, the slag discharge operation is performed, so that the filter cake and the solution attached to the filter cake and mixed in it are flushed into the filter residue tank.

4. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 1, wherein: The descaling and softening device comprises: The shell is in the shape of a hollow cylinder, and a fluid outlet is provided at the upper portion of the shell; a premixing chamber, which is a cylindrical body with a hollow interior and an open top, and is vertically disposed in the lower portion of the shell and spaced a preset distance from the bottom of the shell; at least one black water inlet pipe, each black water inlet pipe being connected to the side wall of the lower portion of the premixing chamber and communicating with the interior of the premixing chamber; at least one medicine introduction tube, each medicine introduction tube being connected to the side wall of the lower portion of the premixing chamber and communicating with the interior of the premixing chamber; A baffle assembly comprising an outer baffle and an inner baffle arranged at intervals, wherein the main body of the outer baffle is cylindrical and fixed to the inner side wall of the shell, the inner side wall of the outer baffle and the outer side wall of the inner baffle are both provided with a wavy structure, and the crests and troughs on the outer baffle are respectively opposite to the crests and troughs on the inner baffle, the upper portion of the inner baffle is cylindrical and is located above the premixing chamber and is separated from the premixing chamber by a preset distance, and the lower portion of the inner baffle is cylindrical and covers the premixing chamber; A stirring assembly, comprising a stirring shaft, a plurality of first stirring blades, a plurality of second stirring blades, and a plurality of third stirring blades; the stirring shaft is rotatably connected to the top and bottom of the shell, and vertically passes through the inner baffle and the premixing chamber, and is rotatably connected to the inner baffle and the premixing chamber; each first stirring blade is located in the premixing chamber, and a first stirring blade is provided above and below the inlet of the black water inlet pipe and the reagent inlet pipe, each second stirring blade is located below the premixing chamber, and each third stirring blade is located above the outer baffle and the inner baffle; The guide assembly includes a plurality of staggered and spaced guide plates, which are respectively located on the inner side wall of the lower part of the inner baffle and the outer side wall of the premixing chamber. The guide plate on the inner baffle is in the shape of an inverted truncated cone and is separated from the premixing chamber by a preset distance. The guide plate on the premixing chamber is in the shape of a truncated cone and is separated from the inner baffle by a preset distance. The guide plate located at the top is arranged on the premixing chamber, and the guide plate is provided with a plurality of circles of annular protrusions spaced along its busbar direction, each circle of protrusions is provided with at least one pair of openings, and the openings on adjacent protrusions on each guide plate are staggered; the fluid on the guide plate on the inner baffle can flow to the innermost protrusion on the guide plate below it, and the fluid on the guide plate on the premixing chamber can flow to the outside of the outermost protrusion on the guide plate below it.

5. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 4, wherein: The descaling and softening device further comprises: At least one ultrasonic component is arranged at the bottom of the shell, and a probe of each ultrasonic component contacts the bottom of the shell.

6. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 4, wherein: Each reagent introduction pipe enters tangentially from the lower part of the premixing chamber and is separated from the bottom of the premixing chamber by a preset distance. The height of each reagent introduction pipe is lower than the height of each black water introduction pipe.

7. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 6, wherein: There are 3 to 6 black water inlet pipes, all of which are evenly distributed on the same circumference, and spiral swirl nozzles are used at the outlets of the black water inlet pipes.

8. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 4, wherein: The inner baffle is connected to the premixing chamber through multiple first connecting rods and to the shell through multiple second connecting rods. The premixing chamber is connected to the shell through multiple third connecting rods. Each first connecting rod, each second connecting rod, and each third connecting rod is separated from the stirring assembly by a preset distance.

9. The method for purifying black water from a coal-water slurry gasification reactor or a carbon scrubber according to claim 4, wherein: The shell, the stirring shaft, the inner baffle, the outer baffle, the premixing chamber and each guide plate are coaxially arranged, the angle between the generatrix of each guide plate and the vertical direction is 30-45 degrees, and the cross section of each circle of protrusions is an upwardly arched arc.

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