Coal conveying and dust cleaning device for thermal power plant

Abstract

The utility model discloses a coal conveying and dust cleaning device for a thermal power plant, belongs to the technical field of coal conveying of thermal power plants, and can effectively reduce dust dissipation of a coal conveying system. Comprising a feeding hopper, an upper-layer conveying system, a first flow control funnel, a second flow control funnel, a three-way material distributor, a coal falling pipe, a third flow control funnel and a lower-layer closed conveying system, the upper-layer conveying system is installed outside the feeding hopper, one end of the first flow control funnel is communicated with the feeding hopper, and the other end of the first flow control funnel is communicated with the three-way material distributor; the second flow control funnel is communicated with one end of a three-way material distributor, one end of the second flow control funnel is communicated with a coal falling pipe, a third flow control funnel is installed at one end of the coal falling pipe, and the bottom of the third flow control funnel is communicated with the front end of the lower-layer closed conveying system. The rear end, away from the third flow control funnel, of the lower-layer closed conveying system is provided with a first wet-type dust removal system, and the middle rear section of the lower-layer closed conveying system is provided with a negative-pressure dust removal system.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of coal conveying system of thermal power plant, specifically is a coal conveying dust removal device for thermal power plant. BACKGROUND

[0002] The belt conveying is a common coal conveying mode in the operation of the power station of the thermal power plant, the coal is conveyed from the freight yard or the mine to the coal yard or the coal storage warehouse of the power plant through the belt transmission, and then the coal is conveyed to the boiler through the mechanical equipment or the pipeline for combustion.

[0003] The existing coal conveying system has the phenomenon that when the coal blocks are separated from the belt conveyor, the coal freely falls, the coal blocks collide and extrude each other between the coal falling pipes, and a large amount of dust is generated when the coal falling pipe is connected to the next belt conveyor, at the same time, the coal falling from the upper layer into the transfer system causes a large amount of dust due to the too fast flow rate, the coal conveying system generates a large amount of dust which is overflowed to cause dust pollution, which pollutes the environment, in addition, the coal extrudes each other at the coal falling pipe and the scraper, and the material accumulation causes great adverse effect on the overall operation of the coal conveying system.

[0004] In order to solve the above technical problems, a closed flow control type transfer system is disclosed in a utility model patent with publication number CN219859596U, which comprises a feeding hopper, an upper conveying system is installed outside the feeding hopper, the closed flow control type transfer system further comprises a first flow control funnel, one end of the first flow control funnel is communicated with the feeding hopper, one end of the first flow control funnel is communicated with a three-way material distributor, a second flow control funnel, one end of the second flow control funnel is communicated with the three-way material distributor, one end of the second flow control funnel is communicated with a coal falling pipe, one end of the coal falling pipe is installed with a third flow control funnel, the bottom of the third flow control funnel is installed with a lower closed conveying system, and a three-way baffle is installed in the three-way material distributor.

[0005] Although the patent can greatly control the generation of dust by controlling the flow rate of the coal falling from the upper conveying system into the three-way material distributor, and the coal falling from the three-way material distributor and the coal falling port into the lower closed conveying system, greatly reduces the pollution of the dust overflow to the environment in the working process, avoids the material accumulation, and reduces the great adverse effect on the overall operation of the coal conveying system, but there is still the problem of dust dispersion.

[0006] The disclosure of the above background art content is only used to assist in understanding the concept and technical scheme of the utility model, which does not necessarily belong to the prior art of the present patent application, and the above background art should not be used to evaluate the novelty and creativity of the present application without clear evidence that the above content has been disclosed on the filing date of the present patent application. The utility model discloses a coal conveying dust removal device for thermal power plant, can effectively reduce the coal conveying system dust dispersion.

[0007] The application provides a coal conveying dust removal device for thermal power plant, which can effectively reduce the coal conveying system dust dispersion.

[0008] To achieve the above object, the application discloses the following technical scheme:

[0009] The application provides a coal conveying dust removal device for thermal power plant, which can effectively reduce the coal conveying system dust dispersion.

[0010] In some possible embodiments, the upper conveying system is provided with a second wet dust removal system at the end.

[0011] In some possible embodiments, the inside of the feeding hopper is provided with a coal falling baffle, and the coal falling baffle is in the shape of a 60° circular arc.

[0012] In some possible embodiments, the negative pressure dust removal system is arranged at 6-9 meters of the lower closed conveying system.

[0013] In some possible embodiments, the negative pressure dust removal system comprises a first induced draft fan and a dust removal unit, the first induced draft fan is used to suck dust-containing air from a dust suction air port into the dust removal unit through the generation of a negative pressure field and the dust removal.

[0014] In some possible embodiments, the negative pressure dust removal system further comprises a second induced draft fan, the second induced draft fan is connected with the dust removal unit, the second induced draft fan is arranged at the 9th meter of the lower closed conveying system, and the second induced draft fan has a processing air volume of 7560 m 3 / h, a filtering area of 45 m 2 , a resistance of 1200 pa, a wind speed of 2.7 m / min, and a full pressure range of 2497-2184 pa.

[0015] In some possible embodiments, a microwave sensor is installed at a position 5 meters away from the third flow control funnel in the coal falling pipe, and the microwave sensor is connected with the controller of the negative pressure dust removal system.

[0016] The one or more technical solutions provided by the embodiments of the present application have at least the following technical effects or advantages:

[0017] 1. The material enters the transfer station from the upper conveying system, first passes through the 60° arc-shaped coal falling baffle to weaken the impact force and prevent the material from penetrating the flow guide cover, then passes through the first flow control funnel to control the flow rate of the material falling into the three-way material distributor, is distributed by the three-way baffle, then passes through the second flow control funnel to control the flow rate of the material falling into the lower closed conveying system, and the negative pressure dust removal system is arranged at the rear section of the lower closed conveying system to remove the induced air flow affected by the transfer belt at the dust transfer point in the transfer room by using the pressure difference formed by the material falling and the action of the induced draft fan, and a wet dust removal system is arranged at the end of the lower closed conveying system to perform secondary dust removal, so that efficient flow control and dust removal are realized, dust pollution is reduced, and stable operation of the system is ensured.

[0018] 2. The lower closed conveying system not only can receive the material falling from the upper layer, but also forms a closed space with the entire transfer system. The closed structure can prevent dust from overflowing, and the negative pressure state in the closed space can accelerate evaporation of water on the surface of the material, so that drying treatment of the wetted material is realized.

[0019] 3. The coal dust concentration in the closed flow control transfer system is detected by means of the intelligent microwave detection technology, and the power of the induced draft fan is intelligently adjusted according to the coal dust concentration, so that the equipment is prevented from being in a high-load or low-efficiency operation state for a long time, the service life of the induced draft fan and other equipment is significantly prolonged, and the equipment maintenance and replacement costs are reduced.

[0020] 4. The second wet dust removal system is arranged at the end of the upper conveying system, and continuously performs the spraying operation, so that the coal dust at the scraper can be maximally settled into the closed transfer station. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. It should be understood that the same reference numerals in all the drawings represent the same elements. In the drawings, the sizes of some features can be deformed for the purpose of clarity and convenience of understanding.

[0022] Figure 1 Fig. 1 is a structural schematic diagram of a coal conveying and dust removal device for a thermal power plant according to some embodiments of the present application;

[0023] Figure 2 Fig. 2 is an internal structural schematic diagram of the coal conveying and dust removal device for the thermal power plant shown in Fig. 1; and Figure 1 Fig. 3 is a structural schematic diagram of a coal conveying and dust removal device for a thermal power plant according to some embodiments of the present application.

[0024] Figure 3 A structural schematic diagram of a coal conveying and dust cleaning device for a thermal power plant is provided for some other embodiments of the present application.

[0025] Figure 4 A schematic diagram of a wet dust removal technology;

[0026] Figure 5 A schematic diagram of a negative pressure dust removal technology;

[0027] Figure 6 A material particle parameter diagram;

[0028] Figure 7 A Figure 3 A flow rate schematic diagram of the coal conveying and dust cleaning device for a thermal power plant shown in FIG. 1;

[0029] Figure 8 A Figure 7 A flow rate curve diagram of the four places circled in FIG. 2;

[0030] Figure 9 A Figure 3 A pressure simulation diagram of the closed flow control transfer system of the coal conveying and dust cleaning device for a thermal power plant shown in FIG. 3.

[0031] Explanation of reference signs:

[0032] 1, feed hopper; 2, first flow control funnel; 3, three-way material distributor; 4, second flow control funnel; 5, coal drop pipe; 6, third flow control funnel; 7, lower layer closed conveying system; 8, negative pressure dust removal system; 81, first induced draft fan; 82, dust removal unit; 83, second induced draft fan; 84, microwave sensor; 9, upper layer conveying system; 10, coal drop baffle; 11, three-way baffle; 12, first wet dust removal system; 13, second wet dust removal system. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] It should be noted that in the description of the present application, the terms "middle", "upper", "lower", "horizontal", "inner", and the like indicating the direction or positional relationship of the terms are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0035] Further, it needs to be explained that, in the description of the utility model, unless another explicit provision and limitation, the terms "arrange", "install", "connect", "connect" should be broad understanding, for example, can be fixed connection, can be detachable connection, or integrally connected, can be mechanical connection, can be directly connected, can be indirectly connected through the intermediate medium, can be the communication inside two elements. For the person skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0036] Please refer to Figures 1-5 The embodiment of the application provides a coal conveying dust removal device for thermal power plant, which comprises a feeding hopper 1, an upper conveying system 9, a first flow control funnel 2, a second flow control funnel 4, a three-way material distributor 3, a coal falling pipe 5, a third flow control funnel 6 and a lower closed conveying system 7, the upper conveying system 9 is installed outside the feeding hopper 1, the first flow control funnel 2 is communicated with one end of the feeding hopper 1, and the first flow control funnel 2 is communicated with the three-way material distributor 3 at one end; the second flow control funnel 4 is communicated with one end of the three-way material distributor 3, the second flow control funnel 4 is communicated with the coal falling pipe 5 at one end, the third flow control funnel 6 is installed at one end of the coal falling pipe 5, the bottom of the third flow control funnel 6 is communicated with the front end of the lower closed conveying system 7, the three-way material distributor 3 is internally installed with a three-way baffle 11, the rear end of the lower closed conveying system 7 away from the third flow control funnel 6 is installed with a first wet dust removal system 12, and the middle rear section of the lower closed conveying system 7 is installed with a negative pressure dust removal system 8, and the negative pressure dust removal system 8 is located between the first wet dust removal system 12 and the front end of the lower closed conveying system 7.

[0037] In this way, the material enters the feeding hopper 1 from the upper conveying system 9, first reduces the impact force through the coal falling baffle 10, then controls the flow rate of falling into the three-way material distributor 3 through the first flow control funnel 2, is distributed through the three-way baffle 11, then controls the flow rate of entering the cylindrical coal falling pipe 5 through the second flow control funnel 4, and finally falls into the lower closed conveying system 7. The negative pressure dust removal system 8 is arranged in the middle rear section of the lower closed conveying system 7, dust in the transfer room is removed by using the pressure difference formed by the falling of the material and the action of the first induced draft fan 81 and the second induced draft fan 83, the first wet dust removal system 12 is installed at the end of the lower closed conveying system 7 to carry out secondary dust removal, and finally high-efficiency flow control, dust reduction, dust pollution reduction and stable system operation are realized.

[0038] Specifically, the negative pressure dust removal mechanism is as follows: as shown in Figure 5As shown, the application uses a negative pressure dust removal system 8 at the 6m position of the lower closed conveying system 7. Since the entire coal conveying dust removal device of the power plant is in a closed state, the material falling into the coal conveying dust removal device (i.e. the transfer system) from the upper conveying system 9 will form a pressure difference, resulting in a positive pressure in the first to third flow control hoppers 2-6 and the front section of the lower closed conveying system 7. The material reaches the lower closed conveying system 7 from the coal falling pipe 5 and runs upward through the belt, causing induced air flow and traction wind flow, which leads to the diffusion of coal dust and the upward flow through the closed conveying system. A first induced draft fan 81 is installed in the rear section of the lower closed conveying system 7, which is connected to a dust removal unit 82. Under the double action of the first induced draft fan 81 and the dust removal unit 82, the positive pressure is eliminated, thereby greatly removing the dust in the transfer room.

[0039] At the same time, by using the closed transfer system, the moisture on the surface of the material is easily evaporated under low pressure. By precisely controlling the pressure and other parameters, the moisture on the surface of the coal dust is quickly evaporated. The evaporation and desorption process under low pressure removes the moisture from the material, the wet coal dust at the scraper is dried by the negative pressure environment and carried away by the air flow under negative pressure, ensuring that the coal dust does not overflow from the transfer system into the transfer room, thereby improving the dust removal rate.

[0040] Negative pressure dust removal alone cannot completely solve the problem of coal dust, so a first wet dust removal system 12 is installed at the end of the lower closed conveying system 7. After the system is opened, continuous spraying is carried out for secondary dust removal, so that the amount of coal dust overflowing when the material leaves the lower closed conveying system 7 is minimized.

[0041] It can be understood that in most factory conveying systems, there are 15 belt conveyors and 7 transfer stations in a conveying system, and each belt conveyor is 100-151 meters long. In order to achieve maximum dust removal, 6-8 wet dust removal systems will be installed above the remaining closed belt conveyors. Since a small amount of coal dust will also diffuse between the rollers, 6-10 wet dust removal systems will also be installed at the rollers of the entire belt conveyor. The dust removal liquid sprayed from the wet spray above the belt conveyor will fall to the bottom of the material stacking bridge due to gravity, so the wet dust removal system at the roller also plays a role in flushing the residual coal dust at the bottom of the material stacking bridge, which can better collect the dust removal liquid containing coal dust for secondary utilization of coal powder.

[0042] The 7 transfer stations and 15 belt conveyors use a fully closed flow control transfer system combined with "wet + negative pressure" dust removal technology to achieve a dust removal rate of more than 99%.

[0043] Please refer to Figure 3In some embodiments, the upper conveying system 9 is provided with a second wet dust removal system 13 at the end. In this way, the spraying operation can be continuously carried out, so that the coal dust on the scraper can be maximally settled into the enclosed transfer station.

[0044] Please refer to Figure 2 In some embodiments, the coal falling baffle 10 is installed in the inside of the feeding hopper 1, and the coal falling baffle 10 is in the shape of a 60° circular arc. In this way, the impact force can be weakened to prevent the material from penetrating the flow cover.

[0045] In some embodiments, the negative pressure dust removal system 8 is arranged at 6-9 meters of the lower enclosed conveying system 7.

[0046] Please refer to Figure 3 In some embodiments, the negative pressure dust removal system 8 includes a first induced draft fan 81 and a dust removal unit 82. The first induced draft fan 81 is used to suck the dust-containing air from the dust suction port into the dust removal unit 82 through the air inlet pipeline by generating a negative pressure field.

[0047] Specifically, the first induced draft fan 81 sucks the dust-containing air from the dust suction port into the filter chamber of the dust removal unit 82 through the generation of a negative pressure field. The dust-containing gas flows from the outside to the inside of the filter bag in the filter chamber. The dust is intercepted on the outer surface of the filter bag, and the clean gas penetrates the filter bag into the inside thereof. The clean gas flows upward to the clean gas chamber (clean gas collection space) of the dust removal unit 82, and then is discharged into the atmosphere through the air outlet pipeline after being accelerated by the ejector.

[0048] The ejector is the core component of the dust removal system of the dust removal unit 82. The dust on the outer surface of the filter bag is stripped and falls into the ash hopper for temporary storage by generating a high-speed pulse air flow through compressed air at regular intervals. During the dust removal process, the clean gas chamber and the filter chamber are isolated by the switching valve to prevent secondary dust raising. Finally, the dust is concentrated and treated by the ash hopper, and the purification cycle of the dust-containing gas is completed.

[0049] Please refer to Figure 3 In some embodiments, the negative pressure dust removal system 8 further includes a second induced draft fan 83 connected to the dust removal unit 82. The second induced draft fan 83 is arranged at the 9th meter of the lower enclosed conveying system 7. The processing air volume of the second induced draft fan 83 is 7560 m 3 / h, the filtration area is 45 m 2 , the resistance is 1200 pa, the air speed is 2.7 m / min, and the total pressure range is 2497-2184 pa.

[0050] Please refer to Figure 3In some embodiments, a microwave sensor 84 is installed at a distance of 65 meters from the third flow control funnel 65 in the coal drop pipe 5, and the microwave sensor 84 is connected to the controller of the negative pressure dust removal system 8. In this way, the microwave sensor 84 can timely capture the influence of coal dust particles on the microwave signal and transmit the coal dust concentration data to the distributed control system for analysis. The distributed control system can monitor the coal dust concentration in real time. If the concentration is close to or greater than the upper limit value, the power of the first induced draft fan 81 and / or the second induced draft fan 83 can be appropriately increased to enhance the suction force and ensure that more coal dust is sucked into the dust collector for treatment. If the concentration is close to or less than the lower limit value, the power can be appropriately reduced. The dust removal efficiency is improved, the service life of the induced draft fan is effectively prolonged, and the maintenance and replacement costs of the equipment are reduced.

[0051] It should be noted that, Figure 3 The system of the coal dust removal device for a thermal power plant is used as follows: in the initial upper transportation link, the material is stably transported toward the closed transfer station through the upper transportation system. A scraper is arranged at the end of the upper transportation belt as the first "defense line" for dust removal. At the same time, the second wet dust removal system 13 continuously works, and water mist is continuously sprayed on the material to greatly reduce the probability of dust generation during material transportation. When the material reaches the closed transfer station, the material is buffered when passing through the arc-shaped coal drop baffle 10, and then is slowed down through the first flow control funnel 2, the second flow control funnel 4, the third flow control funnel 6, and the coal drop pipe 5, so that the material enters the next link stably and orderly, the flow rate of the material is controlled, and the problem of dust generation due to excessive speed is prevented. After entering the lower closed transportation system, a microwave sensor 84 is arranged 5 meters in front of the third flow control funnel 6 to detect the coal dust concentration in the system and transmit the data to the controller of the negative pressure dust removal system 8 for intelligent adjustment of the power of the first induced draft fan 81 and / or the second induced draft fan 83. The first induced draft fan 81 and the second induced draft fan 83 accurately suck the dust-containing air into the dust removal unit 82 adapted thereto to rapidly purify the transportation environment. At the end of the lower closed transportation system 7, there is also the first wet dust removal system 12 as the "defense line". After the system is started, the spray again plays a role in secondary dust removal of the material. After a series of measures, when the material leaves the 12-meter-long lower closed transportation system 7, the amount of dust overflow is extremely small, the pollution to the surrounding environment is reduced to the minimum, and the dual effects of efficient material transportation and environmental dust reduction are achieved.

[0052] The simulation experiment of the embodiment of the present application is as follows:

[0053] As shown in Table 2-1, the improvement effect of the closed flow control transfer station is demonstrated based on EDEM discrete element simulation:

[0054] Object Parameter Unit Material name Coal dust Material density 1580 kg / m 3 ]] Poisson's ratio 0.4 Shear modulus 1.1 x 10 7 ]]> Shear modulus / pa Restoring parameter (coal dust-coal dust) 0.5 Static friction coefficient (coal dust-coal dust) 0.6 Dynamic friction coefficient (coal dust-coal dust) 0.4 Bulk density 0.85 kg / m 3 ]] Conveying capacity 1000 t / h

[0055] Based on field research, it was found that the diameter of pulverized coal in most thermal power plants is generally 30-70 μm. Therefore, a simulation model of pulverized coal particles with a diameter of 50 μm was developed. Figure 6 As shown.

[0056] like Figure 7 and Figure 8 As shown, for Figure 3 The flow rate of the coal conveying dust removal device in the thermal power plant was tested at four locations. The results are as follows: at location 1, there is a significant deceleration effect; at location 2, small material accumulation occurs, buffering the material falling from location 1 and slowing down the speed; at location 3, material accumulation is prevented and the flow rate is increased; at location 4, flow control is implemented to slow down the material flowing down from location 3 and allow it to fall into the lower closed conveying system 7.

[0057] To effectively address the coal dust problem in the closed transfer system, a negative pressure dust removal system 8 is installed in the 6-9 meter section of the lower closed conveyor system 7. For example... Figure 9 As shown, given that the entire transfer station is in a closed state, a pressure difference will be generated when the material falls from the upper conveyor system 9 into the transfer system, thereby forming a positive pressure within the first flow control funnel 2 to the third flow control funnel 6 and the first 6 meters of the lower closed conveyor system 7. At the same time, after the material reaches the lower closed conveyor system 7 from the coal drop pipe 5, induced airflow and traction airflow will be generated during the upward transport of the material by the belt, causing coal dust to diffuse and flow upward through the closed conveyor system.

[0058] A first induced draft fan 81 is installed at a height of 6-9 meters in the lower enclosed conveying system 7. The first induced draft fan 81 is connected to a dust collector, and the two work together to eliminate positive pressure and reduce the coal dust content in the transfer room. When the coal dropper is started, due to the time interval between coal drops, this time difference is used to put the lower conveying system into a negative pressure state. At the same time, the intelligent microwave detection system monitors the coal dust concentration in real time and precisely adjusts the power of the first induced draft fan 81. With the coordinated operation of the dust collector, the coal dust concentration is effectively controlled, ensuring the safe and efficient operation of the conveying system in a low-coal-dust environment.

[0059] Meanwhile, pressure simulation of the entire closed-loop flow control system was performed based on ANSYS finite element analysis. It can be seen that, with the upper conveyor system 9 as the air inlet and the lower closed-loop conveyor system 7 as the air outlet, the pressure is 19424 Pa when material is conveyed from the upper conveyor system 9 into the closed-loop transfer system via belt conveyor. When the material reaches the cylindrical coal drop pipe 5, the pressure becomes 20939 Pa. When the material falls into the lower closed-loop system, the upward movement of the belt conveyor causes the originally stable air to flow upward, resulting in a pressure difference that increases the pressure to 21848 Pa.

[0060] A second induced draft fan 83 is added at the 9-meter mark of the closed conveyor system. This second induced draft fan 83 has a processing capacity of 7560 m³ / h. 3 / h, the filtration area is 45m 2 The second induced draft fan 83 forms a negative pressure field, and the dust-containing air is sucked into the dust removal unit 82 matched with the second induced draft fan 83 through the second induced draft fan 83. The second induced draft fan 83 is connected with the dust removal unit 82. The dust-containing gas enters the filter chamber through the air inlet, passes through the dust collector from outside to inside, and the dust is blocked on the outer surface of the filter bag. The clean gas enters the bag, passes through the ejector and the clean gas chamber, and is discharged into the atmosphere from the air outlet.

[0061] When the running time of the dust collector reaches the preset cleaning and dust discharging time, the compressed gas in the gas tank is sprayed out through the output pipe, enters the annular channel of the ejector through the plug-in pipe, and is sprayed downward from the annular channel at the speed of sound, forming a vacuum at the upper part of the ejector. Part of the air (i.e. secondary airflow) in the clean gas chamber is induced to enter, and the compressed air and the secondary airflow rapidly expand after entering the dust collector, generating impact vibration and forming an external airflow, blowing off the dust attached to the outside of the dust collector and between the fibers, realizing the cleaning of the dust collector, and the cleaned dust falls into the dust discharging port and is discharged by the dust discharging valve. After the spraying is finished, the dust collector returns to the filtering state.

[0062] The above describes the utility model and its implementation mode, and this description is not restrictive. The embodiment shown in the full text is only one of the embodiments of the utility model, and the actual structure is not limited thereto. In summary, if a person skilled in the art is inspired thereby, without departing from the creative purpose of the utility model, similar structural modes and embodiments can be designed without creativity, which should belong to the protection scope of the utility model.

Claims

1. A coal dust cleaning device for coal conveying in a thermal power plant, comprising a feeding hopper, an upper conveying system, a first flow control funnel, a second flow control funnel, a three-way material distributor, a coal drop pipe, a third flow control funnel and a lower closed conveying system, wherein the feeding hopper is externally provided with the upper conveying system, one end of the feeding hopper is communicated with the first flow control funnel, one end of the first flow control funnel is communicated with the three-way material distributor; one end of the second flow control funnel is communicated with the three-way material distributor, one end of the second flow control funnel is communicated with the coal drop pipe, one end of the coal drop pipe is provided with the third flow control funnel, the bottom of the third flow control funnel is communicated with the front end of the lower closed conveying system, and the inside of the three-way material distributor is provided with a three-way baffle. The first wet dust removal system is installed at the rear end of the third flow control funnel away from the lower closed conveying system, the negative pressure dust removal system is installed at the middle and rear section of the lower closed conveying system, and is located between the first wet dust removal system and the front end of the lower closed conveying system, and the second wet dust removal system is arranged at the end of the upper conveying system.

2. The coal dust cleaning apparatus for a coal-fired power plant according to claim 1, characterized by The inside of the feeding hopper is internally provided with a coal falling baffle in the shape of a 60° circular arc.

3. The coal dust cleaning apparatus for coal-fired power plants according to claim 2, characterized by The negative pressure dust removal system is arranged at 6-9 meters of the lower closed conveying system.

4. The coal dust cleaning apparatus for coal-fired power plants according to claim 3, characterized by The negative pressure dust removal system comprises a first air induction fan and a dust removal unit, the first air induction fan is used to suck dust-containing air from the dust suction air port into the dust removal unit through the generation of a negative pressure field for dust removal.

5. The coal dust cleaning apparatus for coal-fired power plants according to claim 4, characterized by The negative pressure dust removal system further comprises a second air induction fan connected with the dust removal unit, the second air induction fan is arranged at the 9th meter of the lower closed conveying system, and the second air induction fan has a processing air volume of 7560 m 3 / h, a filtering area of 45 m 2 , a resistance of 1200 pa, an air speed of 2.7 m / min, and a full pressure range of 2497-2184 pa.

6. The coal dust cleaning device for coal-fired power plants according to any one of claims 1 to 5, characterized in that, A microwave sensor is installed at a position 5 meters away from the third flow control funnel in the coal falling pipe, and the microwave sensor is connected with the controller of the negative pressure dust removal system.

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