Fly ash filtering device and gas washing system

Abstract

The invention provides a fly ash filtering device and a coal gas washing system.The fly ash filtering device is used for filtering coal gas conveyed into a washing tower from a gasification furnace, the fly ash filtering device comprises a conveying pipeline, the conveying pipeline is communicated between the gasification furnace and the washing tower, and the coal gas in the gasification furnace is conveyed into the washing tower through the conveying pipeline; the dust remover is arranged on the conveying pipeline; the flushing pipeline is communicated with the conveying pipeline, a connector is formed at the joint of a water outlet of the flushing pipeline and the conveying pipeline, and the connector is located at the upstream of the dust remover; the filter is arranged between the connector and the dust remover, and the filter can filter out solid impurities and flushing fluid. According to the technical scheme, the problem that in the related technology, fly ash is prone to accumulation in a conveying pipeline, and safe and stable operation of the gasification furnace is affected is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal gas production, and in particular to a fly ash filtering device and a coal gas washing system. Background Art

[0002] The gas washing system includes a gasifier, a washing tower, and a conveying pipeline connecting the gasifier and the washing tower. The gas generated by the gasifier enters the washing tower through the conveying pipeline. After the gasifier has been running for a period of time, the fly ash in the gas is easily accumulated in the conveying pipeline due to the water in the quenching chamber of the gasifier, resulting in ash accumulation, which reduces the inner diameter of the conveying pipeline and forms pipeline resistance. As the pipeline resistance continues to increase, it will affect the safe and stable operation of the gasifier.

[0003] Therefore, in the related art, fly ash in the coal gas is easily accumulated in the transportation pipeline, which increases the pipeline resistance of the transportation pipeline and affects the safe and stable operation of the gasifier. Summary of the invention

[0004] The main purpose of the present invention is to provide a fly ash filtering device and a coal gas washing system to solve the problem in the related art that fly ash is easily accumulated in the conveying pipeline, affecting the safe and stable operation of the gasifier.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a fly ash filtering device for filtering the coal gas transported from the gasifier to the washing tower, the fly ash filtering device comprising: a conveying pipeline connected between the gasifier and the washing tower, and the coal gas in the gasifier is transported to the washing tower through the conveying pipeline; a dust collector arranged on the conveying pipeline; a flushing pipeline connected to the conveying pipeline, and a water outlet of the flushing pipeline forms an interface with a connection point of the conveying pipeline, and the interface is located upstream of the dust collector; a filter is arranged between the interface and the dust collector, and the filter can filter out solid impurities and flushing liquid.

[0006] Furthermore, the water inlet of the flushing pipeline is connected to the flushing pipeline of the washing tower.

[0007] Furthermore, a pressure energy recovery device is provided on the flushing pipeline, and the pressure energy recovery device can reduce the liquid pressure in the flushing pipeline and recover the reduced liquid pressure.

[0008] Furthermore, the filter has a discharge port for discharging solid impurities and flushing liquid, and the discharge port is connected to the slag discharge port of the gasifier.

[0009] Furthermore, the filter is a gas filtering sintered felt or a precision gas filter or a Y-type filter or a full liquid filter membrane or a sampling and analysis filter.

[0010] Furthermore, the dust collector is a Venturi scrubber or a Venturi dust collector.

[0011] Furthermore, a spray structure is provided at the interface, a water inlet of the spray structure is connected to a water outlet of the flushing pipeline, and a water outlet of the spray structure is connected to a pipe wall of the conveying pipeline.

[0012] Furthermore, the spray structure includes a first pipeline, a water inlet of the first pipeline is connected to a water outlet of the flushing pipeline, a water outlet of the first pipeline is connected to a pipe wall of the first pipeline, and the water outlet of the first pipeline is located above the axis of the flushing pipeline.

[0013] Furthermore, the spray structure also includes a second pipeline, there are multiple second pipelines, and the first pipeline and each second pipeline are arranged at equal intervals along the circumference of the flushing pipeline.

[0014] According to another aspect of the present invention, a coal gas washing system is provided, comprising a gasifier, a washing tower, and a fly ash filtering device connected between the gasifier and the washing tower, wherein the fly ash filtering device is the above-mentioned fly ash filtering device.

[0015] By applying the technical solution of the present invention, a fly ash filtering device is used to filter the coal gas transported from the gasifier to the washing tower. The fly ash filtering device includes: a conveying pipeline, a dust collector, a flushing pipeline and a filter. The conveying pipeline is connected between the gasifier and the washing tower, and the coal gas in the gasifier is transported to the washing tower through the conveying pipeline. The dust collector is arranged on the conveying pipeline. The flushing pipeline is connected to the conveying pipeline, and the water outlet of the flushing pipeline forms an interface with the connection of the conveying pipeline, and the interface is located upstream of the dust collector. The filter is arranged between the interface and the dust collector, and the filter can filter out solid impurities and flushing liquid. In this way, the flushing pipeline can spray and clean the coal gas output from the gasifier, so that the fly ash in the coal gas can be combined with the flushing liquid, and after being filtered by the filter, the flushing liquid and the solid impurities formed by the fly ash in the flushing liquid are filtered, and then the dust collector performs further dust removal operations on the cleaned and filtered coal gas, so as to further reduce the fly ash content in the coal gas, so as to reduce the fly ash content of the coal gas entering the scrubber, reduce the scaling phenomenon of the downstream equipment, and also enable the gasifier to operate safely and stably. In addition, through the arrangement of the flushing pipeline and the filter, the fly ash in the coal gas can enter the flushing liquid by spraying and cleaning, and the filter can filter and discharge the solid impurities formed by the fly ash in the flushing liquid together with the flushing liquid, thereby reducing the accumulation of fly ash in the coal gas in the conveying pipeline, reducing the possibility of increasing the pipeline resistance of the conveying pipeline, and improving the safety of the gasifier when in use. Therefore, the technical solution of the present application effectively solves the problem in the related art that fly ash is easy to accumulate in the conveying pipeline, affecting the safe and stable operation of the gasifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A schematic diagram showing the pipeline connection of an embodiment of a coal gas scrubbing system according to the present invention is shown;

[0018] Figure 2 Shows Figure 1 Schematic diagram of the pipe connection at the spray structure of the gas washing system.

[0019] The above drawings include the following reference numerals:

[0020] 10. Gasifier;

[0021] 20. Scrubber;

[0022] 30. Delivery pipeline;

[0023] 40. Dust collector;

[0024] 50. Flushing pipeline; 51. Pressure energy recovery device;

[0025] 60. Filter;

[0026] 70. Spraying structure; 71. First pipeline; 72. Second pipeline. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0030] In this embodiment, if Figure 1 As shown, the fly ash filtering device is used to filter the coal gas transported from the gasifier 10 to the washing tower 20. The fly ash filtering device includes: a conveying pipeline 30, a dust collector 40, a flushing pipeline 50 and a filter 60. The conveying pipeline 30 is connected between the gasifier 10 and the washing tower 20, and the coal gas in the gasifier 10 is transported to the washing tower 20 through the conveying pipeline 30. The dust collector 40 is arranged on the conveying pipeline 30. The flushing pipeline 50 is connected to the conveying pipeline 30, and the water outlet of the flushing pipeline 50 forms an interface with the connection of the conveying pipeline 30, and the interface is located upstream of the dust collector 40. The filter 60 is arranged between the interface and the dust collector 40, and the filter 60 can filter out solid impurities and flushing liquid.

[0031] In this way, the flushing pipeline 50 can spray and clean the coal gas output from the gasifier 10, so that the fly ash in the coal gas can be combined with the flushing liquid, and filtered by the filter 60, the flushing liquid and the solid impurities formed by the fly ash in the flushing liquid are filtered, and then the dust collector 40 performs further dust removal operations on the cleaned and filtered coal gas, so as to further reduce the fly ash content in the coal gas, so as to reduce the fly ash content of the coal gas entering the washing tower 20, reduce the scaling phenomenon of the downstream equipment, and also enable the gasifier 10 to operate safely and stably. In addition, through the arrangement of the flushing pipeline 50 and the filter 60, the fly ash in the coal gas can enter the flushing liquid by spraying and cleaning, and the filter 60 can filter and discharge the solid impurities formed by the fly ash in the flushing liquid together with the flushing liquid, thereby reducing the accumulation of fly ash in the coal gas in the conveying pipeline 30, reducing the possibility of increasing the pipeline resistance of the conveying pipeline 30, and improving the safety of the gasifier 10 when in use. Therefore, the technical solution of this embodiment effectively solves the problem in the related art that fly ash is easily accumulated in the conveying pipeline 30 , affecting the safe and stable operation of the gasifier 10 .

[0032] like Figure 1 As shown, the water inlet of the flushing pipeline 50 is connected to the flushing pipeline of the washing tower 20. In this way, the flushing liquid in the flushing pipeline of the washing tower 20 can be provided to the flushing pipeline 50, making the structure simpler and more compact, and easy to process.

[0033] like Figure 1 As shown, a pressure energy recovery device 51 is provided on the flushing pipeline 50, and the pressure energy recovery device 51 can reduce the liquid pressure in the flushing pipeline 50 and recover the reduced liquid pressure. Since the flushing liquid pressure in the flushing pipeline of the washing tower 20 is relatively high, and the pressure requirement of the flushing liquid in the flushing pipeline 50 is relatively low, the pressure of the flushing liquid can be reduced and the pressure energy can be recovered by providing the pressure energy recovery device 51, thereby reducing energy waste.

[0034] In this embodiment, the pressure energy recovered by the pressure energy recovery device 51 can be used for power generation. The pressure energy recovery device 51 is preferably a hydraulic turbine, a positive displacement energy recovery device, a PX energy recovery device, a TURBO turbine energy recovery device or a FEDCO energy recovery device. The outlet temperature of the raw coal gas output from the gasifier 10 after the waste heat of the waste boiler and the quenching water cooling in the gasifier 10 is generally 300°C. By setting the flushing pipeline 50 and the filter 60, the fly ash content of the coal gas entering the filter 60 can be effectively reduced, and the service life of the dust collector 40 and the filter 60 can be increased.

[0035] When the pressure energy recovery device 51 is a hydraulic turbine, the hydraulic turbine is directly connected to the pipeline of the high-pressure liquid, and the pressure and flow rate of the liquid are used to drive the turbine to rotate. The hydraulic turbine is installed in the flushing pipeline 50, located between the water inlet and the interface of the flushing pipeline 50, and receives the high-pressure flushing liquid from the flushing pipeline of the washing tower 20. The hydraulic turbine converts the pressure energy of the flushing liquid into mechanical energy. When the flushing liquid flows through the turbine blades, it drives the blades to rotate, thereby driving the generator to generate electrical energy. The rotating turbine also reduces the pressure of the flushing liquid, making it suitable for the use pressure of the flushing pipeline 50.

[0036] When the pressure energy recovery device 51 is a positive displacement energy recovery device, the positive displacement energy recovery device is designed to be suitable for the form of a pump or compressor of the pipeline system, and is installed in the flushing pipeline 50, close to the water inlet or behind it, to capture the energy of the flushing liquid. The pressure energy of the flushing liquid is recovered through the internal volume change. When the flushing liquid passes through, the volume inside the device is reduced, resulting in a pressure drop, and the mechanical energy generated can be converted into electrical energy or used to drive other mechanical devices.

[0037] When the pressure energy recovery device 51 is a PX energy recovery device, the PX energy recovery device is usually installed in a pipeline system between high-pressure and low-pressure liquid flows. In this system, it can be placed between the high-pressure end and the low-pressure end of the flushing pipeline 50 to utilize the difference in flushing liquid pressure. The pressure of the high-pressure flushing liquid is used to drive the piston to move, and the low-pressure liquid or gas is compressed while the piston moves, thereby recovering energy. In this system, it can be used for regulating the flushing liquid pressure and recovering energy.

[0038] When the pressure energy recovery device 51 is a TURBO turbine energy recovery device, the TURBO turbine energy recovery device is installed in the flushing pipeline 50, and the flushing liquid passes through the turbine when flowing from the high pressure to the lower pressure area, and the turbine is located between the water inlet and the interface. The flushing liquid flows through the turbine, driving the turbine blades to rotate, thereby converting the pressure energy into mechanical energy. The rotating turbine can drive the generator to generate electrical energy, or directly transfer the energy to other required mechanical systems.

[0039] When the pressure energy recovery device 51 is a FEDCO energy recovery device, the FEDCO energy recovery device is designed as a part of the high-pressure pump and can be installed on the high-pressure side of the flushing pipeline 50 to directly recover energy using the pressure of the flushing liquid. Through the combination of a high-pressure pump and a low-pressure pump, the discharge end of the high-pressure pump is directly connected to the suction end of the low-pressure pump. The high-pressure flushing liquid passes through the high-pressure pump, and the energy recovery device uses the pressure of the high-pressure flushing liquid to drive the low-pressure pump to work, thereby recovering energy. This system is particularly suitable for high-energy-consuming industrial applications, such as seawater desalination and wastewater treatment systems.

[0040] like Figure 1 As shown, the filter 60 has a discharge port for discharging solid impurities and flushing liquid, so that the solid impurities formed by the fly ash in the flushing liquid can be discharged from the discharge port together with the flushing liquid. The discharge port is connected to the slag discharge port of the gasifier 10. In this way, the flushing liquid and solid impurities can be processed together with the coal slag discharged from the gasifier 10, simplifying the subsequent processing steps and reducing energy consumption. In this embodiment, a slag treatment system is connected downstream of the slag discharge port of the gasifier 10.

[0041] like Figure 1 As shown, the filter 60 is a gas filtering sintered felt or a precision gas filter or a Y-type filter or a full liquid filter membrane or a sampling and analysis filter. The above configuration enables the filter 60 to intercept and filter solid impurities and flushing liquid, and discharge them so that the filtered coal gas can pass.

[0042] Among them, gas filtration sintered felt is a specially designed filter material, which is often used for high temperature gas filtration, such as in the treatment of coal gas, flue gas and industrial waste gas. The gas filtration sintered felt is made of multiple layers of sintered metal powder to form a microporous structure. When the filter 60 is a gas filtration sintered felt, when the coal gas passes through these micropores, solid impurities and droplets are intercepted because their size is larger than the pore size, and clean coal gas can pass through. This filter 60 can usually withstand high temperature and corrosion, and is suitable for filtering coal gas in the gasifier 10.

[0043] Among them, precision gas filters are a type of filtration equipment designed to remove fine impurities from gases, including dust, oil mist, and water droplets. Precision gas filters usually contain fine filter media, such as cellulose, glass fiber, or synthetic fiber materials. These filter media capture impurities through depth filtration and surface filtration mechanisms, allowing clean gas to pass through. The depth filtration mechanism captures impurities through the tortuous channels inside the medium, while the surface filtration forms a layer of filter cake on the surface of the medium to prevent impurities from passing through.

[0044] Among them, the Y-type filter is a common industrial filtration equipment, mainly used to remove large particle impurities in liquid or gas flow. There is a detachable filter basket inside the Y-type filter. When the gas flows through the filter basket, larger solid impurities are intercepted in the basket, and the clean gas can continue to flow through the micropores on the basket. Regular cleaning or replacement of the filter basket can maintain its filtration efficiency.

[0045] Among them, the full liquid filter membrane is a special filter 60 that uses liquid as a filter medium and is suitable for removing fine particles and droplets in the gas. The full liquid filter membrane forms a dynamic filter membrane through the liquid. When the gas passes through this membrane, the viscosity of the membrane can capture and separate solid particles and droplets. The clean gas can continue to flow through the micropores of the liquid filter membrane. This filter 60 is particularly suitable for processing humid gas and gas containing fine particles.

[0046] Among them, the sampling and analysis filter is usually used for pretreatment before gas sampling, and its function is to remove impurities in the gas to ensure the accuracy of the analysis. The sampling and analysis filter contains one or more layers of filter media, such as microporous membranes, filter nets, etc., which are used to remove solid particles, droplets and chemicals in the gas. This filter 60 usually requires high filtration efficiency and low resistance to ensure the quality of the sampled gas and reduce the impact on the system flow. Figure 1 As shown, the dust collector 40 is a Venturi scrubber or a Venturi dust collector. The above-mentioned structure is simple, easy to process, and can effectively remove dust from the coal gas. The Venturi scrubber or the Venturi dust collector is arranged upstream of the washing tower 20 as a part of the fly ash filtering device to further capture and remove fine particles in the coal gas, ensure the cleanliness of the coal gas, thereby reducing the impact on subsequent equipment and pollution to the environment.

[0047] Among them, the core component of the Venturi scrubber is the Venturi tube, which is a specially shaped pipe with a narrow middle part and wide ends. When the coal gas containing fly ash or other impurities passes through the narrow part of the Venturi tube, the pressure decreases due to the increase in flow rate. According to the Bernoulli principle, the fluid pressure is inversely proportional to the flow rate. At this time, the scrubbing liquid injected upstream of the narrow part of the Venturi tube will be sucked in and atomized by the high-speed flowing coal gas to form extremely fine droplets. These droplets collide with and adsorb the fly ash particles in the gas, bringing the particles into the liquid phase. The scrubbed gas is decelerated in the expansion section behind the narrow part of the Venturi tube, and the remaining droplets are separated from the gas by inertial separation or other methods, such as a cyclone separator, an electrostatic precipitator 40, etc., and the clean gas continues to flow to subsequent processing equipment or discharge.

[0048] Among them, the working principle of the Venturi dust collector is similar to that of the Venturi scrubber, but scrubbing fluid is usually not used. It mainly relies on the strong turbulence generated by the high-speed flowing gas in the narrow part of the Venturi tube to make the fly ash particles in the gas collide with each other and with the tube wall, thereby increasing weight and precipitating from the airflow. The gas flow rate in the narrow part is very large, which can generate enough turbulence to separate fine particles from the airflow. The separated particles are collected by a collection device, while the clean gas continues to flow downstream after slowing down in the expansion section.

[0049] like Figure 1 As shown, a spray structure 70 is provided at the interface, the water inlet of the spray structure 70 is connected to the water outlet of the flushing pipeline 50, and the water outlet of the spray structure 70 is connected to the pipe wall of the conveying pipeline 30. The arrangement of the spray structure 70 can better spray the flushing liquid into the flushing pipeline 50, so that the fly ash in the coal gas can better contact with the flushing liquid.

[0050] like Figure 1 and Figure 2 As shown, the spray structure 70 includes a first pipeline 71, and the water inlet of the first pipeline 71 is connected to the water outlet of the flushing pipeline 50. The water outlet of the first pipeline 71 is connected to the pipe wall of the first pipeline 71, and the water outlet of the first pipeline 71 is located above the axis of the flushing pipeline 50. In this way, the flushing liquid sprayed from the water outlet of the first pipeline 71 can be sprayed downward, so as to increase the coverage area of ​​the flushing liquid sprayed from the water outlet of the first pipeline 71 in the first pipeline 71, so that the fly ash in the coal gas can be better contacted with the flushing liquid.

[0051] like Figure 1 and Figure 2As shown, the spray structure 70 further includes a second pipeline 72, and there are multiple second pipelines 72. The first pipeline 71 and each second pipeline 72 are arranged at equal intervals along the circumference of the flushing pipeline 50. The arrangement of multiple second pipelines 72 can increase the coverage area of ​​the flushing liquid sprayed by the spray structure 70 in the first pipeline 71, so that the fly ash in the coal gas can be better contacted with the flushing liquid.

[0052] In this embodiment, there are two second pipelines 72 and one first pipeline 71. One first pipeline 71, one second pipeline 72 and another second pipeline 72 are arranged at equal intervals along the circumference of the flushing pipeline 50, and the flushing water sprayed from the first pipeline 71 and the two second pipelines 72 is evenly distributed at 120° with the axis of the delivery pipeline 30 as the center. The angle between the axis of the flushing pipeline 50 and the axis of the delivery pipeline 30 is 60°.

[0053] The present application also provides a coal gas washing system, which includes a gasifier 10, a washing tower 20, and a fly ash filtering device connected between the gasifier 10 and the washing tower 20, and the fly ash filtering device is the above-mentioned fly ash filtering device. Since the above-mentioned fly ash filtering device can solve the problem in the related art that fly ash is easily accumulated in the conveying pipeline 30, affecting the safe and stable operation of the gasifier 10, the coal gas washing system having the fly ash filtering device can solve the same technical problem.

[0054] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0055] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0056] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fly ash filtering device, used for filtering the coal gas transported from a gasification furnace (10) to a washing tower (20), characterized in that: The fly ash filtering device comprises: a conveying pipeline (30) connected between the gasifier (10) and the washing tower (20), and the coal gas in the gasifier (10) is conveyed to the washing tower (20) through the conveying pipeline (30); A dust collector (40) is arranged on the conveying pipeline (30); A flushing pipeline (50) is connected to the conveying pipeline (30), and a water outlet of the flushing pipeline (50) forms an interface with a connection point of the conveying pipeline (30), and the interface is located upstream of the dust collector (40); A filter (60) is arranged between the interface and the dust collector (40), and the filter (60) is capable of filtering out solid impurities and flushing liquid.

2. The fly ash filtering device according to claim 1, characterized in that: The water inlet of the flushing pipeline (50) is connected to the flushing pipeline of the washing tower (20).

3. The fly ash filtering device according to claim 2, characterized in that: The flushing pipeline (50) is provided with a pressure energy recovery device (51), and the pressure energy recovery device (51) is capable of reducing the liquid pressure in the flushing pipeline (50) and recovering the reduced liquid pressure.

4. The fly ash filtering device according to claim 1, characterized in that: The filter (60) has a discharge port for discharging the solid impurities and the flushing liquid, and the discharge port is connected to the slag discharge port of the gasifier (10).

5. The fly ash filtering device according to claim 1, characterized in that: The filter (60) is a gas filtering sintered felt or a precision gas filter or a Y-type filter or a full liquid filter membrane or a sampling analysis filter.

6. The fly ash filtering device according to claim 1, characterized in that: The dust collector (40) is a Venturi scrubber or a Venturi dust collector.

7. The fly ash filtering device according to claim 1, characterized in that: A spray structure (70) is provided at the interface, the water inlet of the spray structure (70) is connected to the water outlet of the flushing pipeline (50), and the water outlet of the spray structure (70) is connected to the pipe wall of the conveying pipeline (30).

8. The fly ash filtering device according to claim 7, characterized in that: The spray structure (70) comprises a first pipeline (71), a water inlet of the first pipeline (71) being connected to a water outlet of the flushing pipeline (50), a water outlet of the first pipeline (71) being connected to a pipe wall of the first pipeline (71), and the water outlet of the first pipeline (71) being located above the axis of the flushing pipeline (50).

9. The fly ash filtering device according to claim 8, characterized in that: The spray structure (70) further comprises a second pipeline (72), the second pipeline (72) being multiple, and the first pipeline (71) and each of the second pipelines (72) being arranged at equal intervals along the circumference of the flushing pipeline (50).

10. A coal gas washing system, comprising a gasifier (10), a washing tower (20) and a fly ash filtering device connected between the gasifier (10) and the washing tower (20), characterized in that: The fly ash filtering device is the fly ash filtering device according to any one of claims 1 to 9.

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