A filtering device for denitrification in a steel plant and its usage method

Abstract

The present invention discloses a filtering device for denitrification in a steel plant and its usage method, including an installation housing. An air inlet channel is communicated with the front surface of the installation housing, and an air outlet channel is communicated with one side of the installation housing. By setting the installation housing, air inlet channel, air outlet channel, installation frame, air guide frame, metal pipe, communication frame, return air frame, first filter screen, return air pipe, pneumatic rotating table, second filter screen, metal frame and cleaning brush, the second filter screen performs basic filtering operations on the flue gas, achieving the effect of intercepting the fly ash impurities with larger particles in the flue gas and reducing the blockage of the external denitrification catalyst. The installation frame, air guide frame, communication frame, return air frame, return air pipe and metal pipe guide the flue gas to be filtered, solving the problem that the traditional filtering device directly filters a large amount of flue gas, which is also prone to local blockage, resulting in an increase in the linear velocity of the flue gas and wear on the filtering device.

Description

Technical Field

[0001] The invention relates to the technical field of steel plant denitration, and in particular to a filtering device for steel plant denitration and a use method thereof. Background Art

[0002] Denitrification in steel mills is a way of treating exhaust gas emissions. Denitrification equipment is used to denitrify exhaust gas emitted by steel mills to meet emission standards and reduce environmental pollution caused by industrial production.

[0003] When traditional steel mills use catalysts for denitrification operations, large particles of fly ash or deposits in the flue gas can easily cause blockage on the inner surface of the catalyst, resulting in a decrease in the activity of the inner surface of the catalyst. At the same time, blockage in local areas means that the flue gas can only circulate in unblocked areas, which increases the linear velocity of the flue gas and increases the wear and loss of the catalyst. Therefore, the flue gas that needs to be denitrified is initially filtered. However, traditional filtering devices directly filter large amounts of flue gas, which is also prone to local blockage, which in turn causes the linear velocity of the flue gas to increase and causes wear on the filtering device. Summary of the invention

[0004] The purpose of the present invention is to provide a filtering device for denitrification in a steel plant and a method for using the same, which has the advantage of being easy to filter and solves the problem that when the catalyst is performing denitrification operation, the inner surface of the catalyst is easily blocked by large particles of fly ash or deposition in the flue gas, causing the activity of the inner surface of the catalyst to decrease. At the same time, the blockage in the local area allows the flue gas to flow only in the unblocked area, which accelerates the linear velocity of the flue gas, thereby increasing the wear and loss of the catalyst. Therefore, the flue gas that needs to be denitrified is initially filtered. However, the traditional filtering device directly filters a large amount of flue gas, which is also prone to local blockage, which in turn causes the linear velocity of the flue gas to increase and causes the filtering device to be worn.

[0005] To achieve the above object, the present invention provides the following technical solution: A filtering device for denitrification in a steel plant, including an installation housing. The front of the installation housing is communicated with an air inlet channel, and one side of the installation housing is communicated with an air outlet channel. Installation frames are fixedly connected to the four sides of the inner cavity of the installation housing. The front and back of the installation frame are both communicated with air guiding frames. One side of the installation frame is communicated with a metal pipe. One end of the metal pipe is communicated with the inner cavity of the air outlet channel. Communicating frames are communicated with the opposite sides of the middle two air guiding frames. The front air guiding frame is communicated with the air inlet channel, and the rear air guiding frame is communicated with a return air frame. The return air frame is fixedly connected to the back of the installation housing. First filter screens are fixedly connected to the upper and lower ends of the inner cavity of the return air frame. An air return pipe is communicated with the top of the return air frame. One end of the air return pipe away from the return air frame is communicated with the inner cavity of the air inlet channel. A one-way valve is communicated with the surface of the air return pipe. A sealing cover is movably connected to the left side of the installation frame, and a pneumatic rotating table is fixedly connected to one side of the sealing cover. The left end of the metal pipe extends into the inner cavity of the installation frame and is sleeved with a second filter screen. A metal frame is fixedly connected to the upper end of the inner cavity of the installation frame, and a cleaning brush is movably connected to the bottom of the metal frame.

[0006] Preferably, a pneumatic reciprocating machine is fixedly connected to one side of the metal frame. The output end of the pneumatic reciprocating machine is fixedly connected to a reciprocating rod. One end of the reciprocating rod penetrates into the inner cavity of the metal frame. The top of the cleaning brush penetrates through the metal frame and is fixedly connected to the reciprocating rod.

[0007] Preferably, a first air inlet pipe is communicated with the top of the pneumatic rotating table. A second air inlet pipe is communicated with the surface of the first air inlet pipe. One end of the second air inlet pipe away from the first air inlet pipe is communicated with the air input end of the pneumatic reciprocating machine.

[0008] Preferably, rotating plates are fixedly connected to both sides of the pneumatic rotating table. The output end of the pneumatic rotating table penetrates into the inner cavity of the installation frame, extends into the inner cavity of the left second filter screen, and is clamped with the pneumatic rotating table through a clamping block.

[0009] Preferably, storage covers are movably connected to the four sides of the left side of the installation housing. Sealing rings are fixedly connected to the four sides of the storage cover close to the installation housing.

[0010] Preferably, an air pump is fixedly connected to the top of the installation housing. The air output end of the air pump is communicated with a conduit, and the conduit is communicated with the four first air inlet pipes through a multi-head pipe.

[0011] Preferably, its usage method steps are as follows:

[0012] A. First, the external gas supply device transports the flue gas that needs to undergo denitrification operation through the intake channel to the inner cavity of the air guide frame, and enters the inner cavity of the front mounting frame through the air guide frame. The flue gas passes through the filtration and interception of the second filter screen in the inner cavity of the front mounting frame, causing some fly ash impurities to be intercepted on the surface of the second filter screen, and allowing some of the filtered waste gas to pass through the second filter screen and enter the inner cavity of the metal pipe and be transported to the inner cavity of the outlet channel, and then enter the denitrification device for denitrification operation;

[0013] B. Next, the flue gas that has not entered the inner cavity of the metal pipe enters the inner cavity of the rear mounting frame through the connection frame, and is filtered again by the second filter screen, allowing some of the filtered flue gas to enter the external denitrification device through the metal pipe and the outlet channel. The remaining part of the flue gas will enter the inner cavity of the return air frame, and after being filtered by the first filter screen, enter the inner cavity of the intake channel through the return air pipe. Under the action of the one-way valve on the surface of the return air pipe, the waste gas is prevented from flowing back;

[0014] C. Then, while the flue gas enters the inner cavity of the mounting frame, the air pump is started through the peripheral controller. The air outlet end of the air pump transports air to the inner cavity of the first intake pipe through the conduit. The first intake pipe transports air to the inner cavity of the pneumatic rotating table, and the output end of the pneumatic rotating table drives the second filter screen and the rotating plate to rotate on the surface of the metal pipe, so that the surface of the second filter screen is evenly contacted with the waste gas, reducing the occurrence of blockage caused by more impurities being filtered in a local area of the second filter screen. At the same time, the rotation of the rotating plate further increases the rotation efficiency of the pneumatic rotating table under the influence of the waste gas flow. In addition, the air in the inner cavity of the first intake pipe enters the inner cavity of the pneumatic reciprocating machine through the second intake pipe. The output end of the pneumatic reciprocating machine drives the reciprocating rod and the cleaning brush to reciprocate, and the cleaning brush scrapes the surface of the second filter screen to extend the service life of the second filter screen;

[0015] D. Finally, when the device needs to be maintained, the hatch can be opened and the pneumatic rotating table in the inner cavity of the installation shell can be removed, and the second filter screen, the cleaning brush and the rotating plate in the inner cavity of the mounting frame can be replaced and maintained. At the same time, the inner cavity of the return air frame can be opened to centrally process the impurities accumulated in the inner cavity of the return air frame.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The present invention provides an installation shell, an air inlet channel, an air outlet channel, an installation frame, an air guide frame, a metal pipe, a connecting frame, a return air frame, a first filter screen, a return air duct, a pneumatic rotating table, a second filter screen, a metal frame and a cleaning brush. The second filter screen performs basic filtering operations on the flue gas, so as to intercept fly ash impurities with larger particles in the flue gas and reduce the blockage of the external denitration catalyst. The installation frame, the air guide frame, the connecting frame, the return air frame, the return air duct and the metal pipe guide the flue gas that needs to be filtered, so that the flue gas continuously circulates through the air inlet channel, the air guide frame, the installation frame, the connecting frame, the return air frame and the return air duct during the circulation process, and part of the flue gas is filtered and flows into the external denitration device through the metal pipe and the air outlet channel during the process, so that a large amount of flue gas is prevented from being directly filtered, and the possibility of local filtering on the surface of the second filter screen is reduced. The first filter screen cooperates with the return air frame to filter and intercept the circulating flue gas, and the air The pneumatic rotating table cooperates with the air pump and the first air inlet pipe to provide a rotating function for the pneumatic rotating table, thereby increasing the uniformity of impurities intercepted on the surface of the second filter screen and reducing the occurrence of local blockage on the surface of the second filter screen. The cleaning brush cooperates with the pneumatic reciprocator and the reciprocating rod to perform reciprocating shaking, and at the same time cooperates with the rotation of the second filter screen to clean the surface of the second filter screen, thereby extending the service life of the second filter screen and solving the problem that when the catalyst is performing denitrification operation, it is easy to be blocked by large particles of fly ash or deposition in the flue gas, causing the inner surface of the catalyst to be clogged, resulting in a decrease in the activity of the inner surface of the catalyst. At the same time, the blockage in the local area allows the flue gas to circulate only in the unblocked area, which accelerates the linear speed of the flue gas, thereby increasing the wear and loss of the catalyst. Therefore, the flue gas that needs to be denitrified is initially filtered, but the traditional filtering device directly filters a large amount of flue gas, which is also prone to local blockage, which in turn causes the linear speed of the flue gas to accelerate and cause the filtering device to wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 It is a three-dimensional structural schematic diagram of the installation frame of the present invention;

[0020] Figure 3 It is a schematic diagram of the explosion structure of the second filter screen of the present invention;

[0021] Figure 4 is a schematic diagram of the three-dimensional structure of the metal frame of the present invention;

[0022] Figure 5 It is a schematic cross-sectional structural diagram of the return air frame of the present invention.

[0023] In the figure: 1. Installation housing; 2. Air intake passage; 3. Air outlet passage; 4. Installation frame; 5. Air guide frame; 6. Metal pipe; 7. Connecting frame; 8. Return air frame; 9. First filter screen; 10. Return air pipe; 11. Pneumatic rotating table; 12. Second filter screen; 13. Metal frame; 14. Cleaning brush; 15. Pneumatic reciprocating machine; 16. Reciprocating rod; 17. First intake pipe; 18. Second intake pipe; 19. Rotating plate; 20. Warehouse cover; 21. Air pump. Detailed implementation manner

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The installation housing 1, air intake passage 2, air outlet passage 3, installation frame 4, air guide frame 5, metal pipe 6, connecting frame 7, return air frame 8, first filter screen 9, return air pipe 10, pneumatic rotating table 11, second filter screen 12, metal frame 13, cleaning brush 14, pneumatic reciprocating machine 15, reciprocating rod 16, first intake pipe 17, second intake pipe 18, rotating plate 19, warehouse cover 20 and air pump 21 components of the present invention are all common standard components or components known to those skilled in the art, and their structures and principles can all be known by those skilled in the art through technical manuals or through conventional experimental methods.

[0026] Please refer to Figures 1-5, A filtering device for denitrification in a steel plant, including an installation housing 1. An air inlet passage 2 is connected to the front of the installation housing 1, and an air outlet passage 3 is connected to one side of the installation housing 1. Installation frames 4 are fixedly connected to the four sides of the inner cavity of the installation housing 1. Air guiding frames 5 are connected to the front and back of the installation frame 4. A metal pipe 6 is connected to one side of the installation frame 4. One end of the metal pipe 6 is connected to the inner cavity of the air outlet passage 3. Connecting frames 7 are connected to the opposite sides of the middle two air guiding frames 5. The front air guiding frame 5 is connected to the air inlet passage 2, and the rear air guiding frame 5 is connected to a return air frame 8. The return air frame 8 is fixedly connected to the back of the installation housing 1. First filter meshes 9 are fixedly connected to the upper and lower ends of the inner cavity of the return air frame 8. An air return pipe 10 is connected to the top of the return air frame 8. One end of the air return pipe 10 away from the return air frame 8 is connected to the inner cavity of the air inlet passage 2. A one-way valve is connected to the surface of the air return pipe 10. A sealing cover is movably connected to the left side of the installation frame 4, and a pneumatic rotary table 11 is fixedly connected to one side of the sealing cover. The left end of the metal pipe 6 extends into the inner cavity of the installation frame 4 and is sleeved with a second filter mesh 12. A metal frame 13 is fixedly connected to the upper end of the inner cavity of the installation frame 4. A cleaning brush 14 is movably connected to the bottom of the metal frame 13. By setting the installation housing 1, the air inlet passage 2, the air outlet passage 3, the installation frame 4, the air guiding frame 5, the metal pipe 6, the connecting frame 7, the return air frame 8, the first filter mesh 9, the air return pipe 10, the pneumatic rotary table 11, the second filter mesh 12, the metal frame 13 and the cleaning brush 14, the second filter mesh 12 performs basic filtering operations on the flue gas, achieving the effect of intercepting larger fly ash impurities in the flue gas and reducing blockage of the external denitrification catalyst. The installation frame 4, the air guiding frame 5, the connecting frame 7, the return air frame 8, the air return pipe 10 and the metal pipe 6 guide the flue gas to be filtered, allowing the flue gas to circulate continuously through the air inlet passage 2, the air guiding frame 5, the installation frame 4, the connecting frame 7, the return air frame 8 and the air return pipe 10 during the circulation process. And during this process, part of the flue gas is filtered and flows into the external denitrification device through the metal pipe 6 and the air outlet passage 3, preventing direct filtration of a large amount of flue gas and reducing the possibility of local filtration on the surface of the second filter mesh 12. The first filter mesh 9 cooperates with the return air frame 8 to filter and intercept the circulating flue gas. The pneumatic rotary table 11 cooperates with the air pump 21 and the first air inlet pipe 17 to provide a rotating function for the pneumatic rotary table 11, increasing the uniformity of intercepted impurities on the surface of the second filter mesh 12 and reducing the occurrence of local blockage on the surface of the second filter mesh 12. The cleaning brush 14 cooperates with the pneumatic reciprocating machine 15 and the reciprocating rod 16 to perform reciprocating shaking, and at the same time cooperates with the rotation of the second filter mesh 12 to clean the surface of the second filter mesh 12, extending the service life of the second filter mesh 12. It solves the problem that when the catalyst performs denitrification operations, it is easily blocked by large particle fly ash or deposition on the inner surface of the catalyst in the flue gas, resulting in a decrease in the activity of the inner surface of the catalyst. At the same time, the blockage in the local area allows the flue gas to only flow in the unblocked area, increasing the linear velocity of the flue gas, thereby increasing the wear and loss of the catalyst. Therefore, the flue gas to be denitrified is preliminarily filtered, but the traditional filtering device directly filters a large amount of flue gas.It is also prone to local blockage, which in turn leads to an increase in the linear velocity of the flue gas and causes wear to the filtering device.

[0027] Specifically, a pneumatic reciprocator 15 is fixedly connected to one side of the metal frame 13. The output end of the pneumatic reciprocator 15 is fixedly connected to a reciprocating rod 16. One end of the reciprocating rod 16 penetrates into the inner cavity of the metal frame 13. The top of the cleaning brush 14 penetrates the metal frame 13 and is fixedly connected to the reciprocating rod 16. By setting the pneumatic reciprocator 15 and the reciprocating rod 16, a basis is provided for the reciprocating movement of the cleaning brush 14.

[0028] Specifically, a first air inlet pipe 17 is communicated with the top of the pneumatic rotary table 11. The surface of the first air inlet pipe 17 is communicated with a second air inlet pipe 18. One end of the second air inlet pipe 18 away from the first air inlet pipe 17 is communicated with the air input end of the pneumatic reciprocator 15. By setting the first air inlet pipe 17 and the second air inlet pipe 18, and cooperating with the air pump 21 to conduct air supply operations for the pneumatic rotary table 11 and the pneumatic reciprocator 15, the pneumatic rotary table 11 and the pneumatic reciprocator 15 are thus operated.

[0029] Specifically, rotating plates 19 are fixedly connected to both sides of the pneumatic rotary table 11. The output end of the pneumatic rotary table 11 penetrates into the inner cavity of the installation frame 4, and extends into the inner cavity of the left second filter screen 12 and is clamped with the pneumatic rotary table 11 through a clamping block. By setting the rotating plates 19, the rotation efficiency of the second filter screen 12 is increased in cooperation with the pneumatic rotary table 11 and the second filter screen 12.

[0030] Specifically, hatch covers 20 are movably connected to the four surrounding sides of the left side of the installation housing 1. Sealing rings are fixedly connected to the four surrounding sides of the hatch covers 20 close to the installation housing 1. By setting the hatch covers 20, it is convenient for the staff to disassemble the hatch covers 20 to maintain the inner cavity of the installation housing 1.

[0031] Specifically, an air pump 21 is fixedly connected to the top of the installation housing 1. The air outlet end of the air pump 21 is communicated with a conduit, and the conduit is communicated with the four first air inlet pipes 17 through a multi-head pipe. By setting the air pump 21, air is supplied to the first air inlet pipe 17 and the second air inlet pipe 18, thereby providing power for the operation of the pneumatic rotary table 11 and the pneumatic reciprocator 15.

[0032] Specifically, its usage method steps are as follows:

[0033] A. First, an external air supply device conveys the flue gas that needs to undergo denitrification operation through the air inlet passage 2 to the inner cavity of the air guide frame 5, and enters the inner cavity of the front installation frame 4 through the air guide frame 5. After the flue gas passes through the filtration and interception of the second filter screen 12 in the inner cavity of the front installation frame 4, part of the fly ash impurities will be intercepted on the surface of the second filter screen 12, and part of the filtered waste gas will pass through the second filter screen 12 and enter the inner cavity of the metal pipe 6 and be transmitted to the inner cavity of the air outlet passage 3, and then enter the denitrification device for denitrification operation;

[0034] B. Next, the flue gas that has not yet entered the inner cavity of the metal pipe 6 enters the inner cavity of the rear mounting frame 4 through the connecting frame 7, and is filtered again by the second filter screen 12. Part of the filtered flue gas passes through the metal pipe 6 and the air outlet channel 3 and enters the external denitration device. The remaining part of the flue gas enters the inner cavity of the return air frame 8, and after being filtered by the first filter screen 9, it enters the inner cavity of the air inlet channel 2 through the return air pipe 10. And under the action of the one-way valve on the surface of the return air pipe 10, the waste gas is prevented from flowing back.

[0035] C. Then, while the flue gas enters the inner cavity of the mounting frame 4, the air pump 21 is started through the peripheral controller. The air outlet end of the air pump 21 conveys air into the inner cavity of the first air inlet pipe 17. The first air inlet pipe 17 conveys air into the inner cavity of the pneumatic rotating table 11, and the output end of the pneumatic rotating table 11 drives the second filter screen 12 and the rotating plate 19 to rotate on the surface of the metal pipe 6, so that the surface of the second filter screen 12 is evenly contacted with the waste gas, reducing the occurrence of blockage caused by more impurities filtered in a local area of the second filter screen 12. At the same time, the rotation of the rotating plate 19 further increases the rotation efficiency of the pneumatic rotating table 11 under the influence of the waste gas flow. In addition, the air in the inner cavity of the first air inlet pipe 17 enters the inner cavity of the pneumatic reciprocating machine 15 through the second air inlet pipe 18. The output end of the pneumatic reciprocating machine 15 drives the reciprocating rod 16 and the cleaning brush 14 to reciprocate, and the cleaning brush 14 scrapes the surface of the second filter screen 12, extending the service life of the second filter screen 12.

[0036] D. Finally, when the device needs to be maintained, the hatch 20 can be opened and the pneumatic rotating table 11 in the installation shell 1 can be removed, and the second filter screen 12, the cleaning brush 14 and the rotating plate 19 in the inner cavity of the mounting frame 4 can be replaced and maintained. At the same time, the inner cavity of the return air frame 8 can be opened to centrally process the impurities accumulated in the inner cavity of the return air frame 8.

[0037] The standard parts used in this application document can all be purchased from the market, and can also be customized according to the records of the specification and the drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding that are mature in the prior art. The machines, parts and equipment all adopt conventional models in the prior art. The control method is automatically controlled through the controller. The control circuit of the controller can be realized by simple programming by those skilled in the art, which belongs to the common knowledge in this field. And this application document is mainly used to protect the mechanical device, so the control method and the circuit connection are not explained in detail in this application document.

[0038] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0039] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A filtering device for denitrification in a steel plant, comprising a mounting housing (1), characterized in that: The front of the installation housing (1) is connected to an air intake channel (2), one side of the installation housing (1) is connected to an air outlet channel (3), installation frames (4) are fixedly connected to the four peripheries of the inner cavity of the installation housing (1), air guiding frames (5) are connected to the front and back of the installation frame (4), a metal pipe (6) is connected to one side of the installation frame (4), one end of the metal pipe (6) is connected to the inner cavity of the air outlet channel (3), communication frames (7) are connected to the opposite sides of the middle two air guiding frames (5), the front air guiding frame (5) is connected to the air intake channel (2), the rear air guiding frame (5) is connected to a return air frame (8), the return air frame (8) is fixedly connected to the back of the installation housing (1), first filters (9) are fixedly connected to the upper and lower ends of the inner cavity of the return air frame (8), an air return pipe (10) is connected to the top of the return air frame (8), one end of the air return pipe (10) far from the return air frame (8) is connected to the inner cavity of the air intake channel (2), a one-way valve is connected to the surface of the air return pipe (10), a sealing cover is movably connected to the left side of the installation frame (4), and a pneumatic rotating table (11) is fixedly connected to one side of the sealing cover. The left end of the metal pipe (6) extends into the inner cavity of the installation frame (4) and is sleeved with a second filter (12). A metal frame (13) is fixedly connected to the upper end of the inner cavity of the installation frame (4), and a cleaning brush (14) is movably connected to the bottom of the metal frame (13); A pneumatic reciprocator (15) is fixedly connected to one side of the metal frame (13), a reciprocating rod (16) is fixedly connected to the output end of the pneumatic reciprocator (15), one end of the reciprocating rod (16) penetrates into the inner cavity of the metal frame (13), and the top of the cleaning brush (14) penetrates through the metal frame (13) and is fixedly connected to the reciprocating rod (16); A first air inlet pipe (17) is connected to the top of the pneumatic rotating table (11), a second air inlet pipe (18) is connected to the surface of the first air inlet pipe (17), and one end of the second air inlet pipe (18) far from the first air inlet pipe (17) is connected to the air input end of the pneumatic reciprocator (15); Rotating plates (19) are fixedly connected to both sides of the pneumatic rotating table (11), the output end of the pneumatic rotating table (11) penetrates into the inner cavity of the installation frame (4), extends into the inner cavity of the left second filter (12) and is clamped with the pneumatic rotating table (11) through a clamping block; Storage covers (20) are movably connected to the four peripheries of the left side of the installation housing (1), and sealing rings are fixedly connected to the four peripheries of the side of the storage cover (20) close to the installation housing (1); An air pump (21) is fixedly connected to the top of the installation housing (1), the air output end of the air pump (21) is connected to a conduit, and the conduit is connected to the four first air inlet pipes (17) through a multi-head pipe.

2. The usage method of a filtering device for denitrification in a steel plant according to claim 1, characterized in that: The usage method steps are as follows: A. First, the external gas supply device transports the flue gas that needs to undergo denitrification operation through the intake channel (2) to the inner cavity of the air guide frame (5), and enters the inner cavity of the front mounting frame (4) through the air guide frame (5). The flue gas passing through the second filter screen (12) in the inner cavity of the front mounting frame (4) will intercept some fly ash impurities on the surface of the second filter screen (12), and let some of the filtered waste gas pass through the second filter screen (12) into the inner cavity of the metal pipe (6) and be transported to the inner cavity of the outlet channel (3), and then enter the denitrification device for denitrification operation; B. Next, the flue gas that has not entered the inner cavity of the metal pipe (6) enters the inner cavity of the rear mounting frame (4) through the connection frame (7), and is filtered again by the second filter screen (12). Let some of the filtered flue gas enter the external denitrification device through the metal pipe (6) and the outlet channel (3). The remaining part of the flue gas will enter the inner cavity of the return air frame (8), and after being filtered by the first filter screen (9), enter the inner cavity of the intake channel (2) through the return air pipe (10). And under the action of the one-way valve on the surface of the return air pipe (10), prevent the waste gas from flowing back; C. Then, when the flue gas enters the inner cavity of the mounting frame (4), start the air pump (21) through the external controller. The air outlet end of the air pump (21) transports air to the inner cavity of the first intake pipe (17) through the conduit. The first intake pipe (17) transports air to the inner cavity of the pneumatic rotating table (11), and the output end of the pneumatic rotating table (11) drives the second filter screen (12) and the rotating plate (19) to rotate on the surface of the metal pipe (6), so that the surface of the second filter screen (12) is evenly contacted with the waste gas, reducing the occurrence of blockage caused by more impurities filtered in a local area of the second filter screen (12). At the same time, the rotation of the rotating plate (19) further increases the rotation efficiency of the pneumatic rotating table (11) under the influence of the waste gas flow. In addition, the air in the inner cavity of the first intake pipe (17) enters the inner cavity of the pneumatic reciprocating machine (15) through the second intake pipe (18). The output end of the pneumatic reciprocating machine (15) drives the reciprocating rod (16) and the cleaning brush (14) to reciprocate, and the cleaning brush (14) scrapes the surface of the second filter screen (12), extending the service life of the second filter screen (12); D. Finally, when the device needs to be maintained, the cover (20) can be opened and the pneumatic rotating table (11) in the inner cavity of the installation shell (1) can be removed, and the second filter screen (12), the cleaning brush (14) and the rotating plate (19) in the inner cavity of the mounting frame (4) can be replaced and maintained. At the same time, the inner cavity of the return air frame (8) can be opened to centrally process the impurities accumulated in the inner cavity of the return air frame (8).

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