Method for maintaining and replacing filtering element of silicon powder filter

Abstract

The invention discloses a method for maintaining and replacing a filtering element of a silicon powder filter, and belongs to the technical field of chemical equipment. The method comprises the following steps: manufacturing a filter element dismounting and mounting bearing mould, dismounting a pipe fitting connected with a pipe orifice of a silicon powder filter end socket, dismounting the silicon powder filter end socket, integrally dismounting the filter element, dismounting the filter element, cleaning a pipe plate, mounting a new filter element, integrally reassembling the filter element, reassembling the silicon powder filter end socket and recovering the pipe fitting connected with the pipe orifice. According to the method disclosed by the invention, the procedures such as disassembly and assembly of the silicon powder filter and maintenance and replacement of the filtering element are more convenient and faster, time and labor are saved, and the disassembly, assembly, replacement and maintenance efficiency of the silicon powder filter is greatly improved, so that the construction period is shortened. According to the method, the working efficiency is improved, meanwhile, the use cost of manpower and machinery is saved, the maintenance cost is reduced, and certain economic value is creative for enterprises.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical equipment, and particularly relates to the maintenance and repair of chemical equipment. Specifically, it is a method for maintaining and replacing the filter element of a silicon powder filter. Background Art

[0002] The silicon powder filter is the main equipment for filtering silicon powder in the tail gas. It mainly separates the silicon powder in the tail gas and collects it in the silicon powder collection tank. The main process flow is that the tail gas enters the equipment from the bottom of the filter, and after passing through the filter element of the filter element, the silicon powder adheres to the surface of the filter element. Nitrogen blows off the silicon powder adhering to the surface of the filter element in a pulsed manner from inside the filter element. The silicon powder enters the silicon powder collection tank through the pipeline at the bottom of the equipment by its own gravity, and the remaining gaseous medium enters the next process flow from the pipeline at the upper part of the silicon powder filter.

[0003] As the main equipment in the tail gas recovery section, the filtration efficiency of the silicon powder filter is crucial. The silicon powder filter belongs to a physical filtration process. During the continuous filtration process, its filter element will be damaged, resulting in a decrease in filtration efficiency. Therefore, in order to ensure the filtration effect, the filter element needs to be replaced frequently.

[0004] When replacing the filter element of the silicon powder filter, there are mainly two traditional replacement methods: The first method is to clean it by the backwashing method, and the second method is to clean and replace it at high altitude after opening the cover of the equipment body. When using the backwashing method for cleaning, there are problems such as incomplete cleaning and poor cleaning effect; when using the method of opening the cover of the equipment body and replacing it at high altitude, there are problems such as easy silicon powder leakage, easy blockage of subsequent equipment and pipelines, high safety risks, low construction efficiency, and high maintenance costs. Moreover, during the process of pulling out the core upwards at high altitude and during the process of replacing the filter element, if the operation is improper, there is a risk of filter element rupture.

[0005] Based on the above problems, a reasonable and standardized construction method must be adopted for the construction of replacing the internal parts of the silicon powder filter to ensure the construction quality. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and provide a method for maintaining and replacing the filter element of a silicon powder filter.

[0007] The present invention is achieved by the following technical solutions: A method for maintaining and replacing the filter element of a silicon powder filter includes the following steps: Step 1, fabricate a disassembly and assembly bearing tool for the filter element; The disassembly and assembly bearing tool for the filter element is a steel structure frame made of steel components. The steel structure frame includes a support part and a platform part. The platform part is fixed at the top of the support part, and a support hole is reserved at the center position of the platform part.

[0008] Step 2: Remove the pipe fittings connected to the nozzle of the silica powder filter head. The pipe fittings connected to the nozzle of the silica powder filter head include: pressure transmitter, backflush nitrogen pipeline, and material outlet pipeline.

[0009] Step 3: Remove the silica powder filter head. Use a paint pen to make 2 - 3 marking lines at the flange positions of the silica powder filter head flange and the silica powder filter cylinder flange, evenly distributed, and remove all the bolts at the flange. Use a crane to lift the silica powder filter head to the pre-prepared sleepers for placement. The height of the sleepers shall not be less than 200 mm.

[0010] Step 4: Remove the filter element as a whole. The filter element is mainly composed of a pressing plate, a tube sheet, a pulling frame, a pull rod, and a filter element. First, remove all the fixing bolts between the tube sheet and the support ring plate inside the silica powder filter, lift the filter element out as a whole and place it on the pre-prepared filter element disassembly and assembly bearing tool. The filter element is stably supported at the support holes on the filter element disassembly and assembly bearing tool.

[0011] Step 5: Remove the filter element. On the filter element disassembly and assembly bearing tool, first remove all the bolts on the pressing plate and the pulling frame, and place the removed bolts in a wooden box to prevent loss; then take out the filter element from bottom to top and transfer it out of the site to prevent mixing with the new filter element.

[0012] Step 6: Clean the tube sheet. On the filter element disassembly and assembly bearing tool, pickle the tube sheet with pickling paste, then rinse it with clean water, and finally dry it with clean air.

[0013] Step 7: Install a new filter element. On the filter element disassembly and assembly bearing tool, first lay cotton gauze on the upper edge and inner surface of the tube sheet nozzle, install the new filter element through the tube sheet nozzle one by one from top to bottom, and pass the bolts at the bottom of the filter element through the bolt holes of the pulling frame correspondingly. After filling, install the pressing plate in place, tighten the bolts, and tighten all the bolts of the pulling frame. The filter element assembly is completed.

[0014] Step 8: Reinstall the filter element as a whole. Lift and install the assembled filter element in place using a crane.

[0015] Step 9: Reinstall the silica powder filter head and restore the pipe fittings connected to the nozzle. When reinstalling the silica powder filter head, reinstall it according to the marked line positions before removal, and tighten all the bolts.

[0016] Further, in step one, the support part consists of four steel columns, the platform part is fixedly connected by a plurality of main steel beams crisscrossing vertically and horizontally, and a plurality of load-bearing beams for supporting the filter element are fixedly connected between the main steel beams around the support holes; a cage straight ladder is fixed on one side of the platform part, a high fence is fixed around the platform part, the top surface of the platform part is covered and fixed with checkered steel plates, and reserved holes adapted thereto are also provided at the positions corresponding to the support holes on the checkered steel plates.

[0017] Further, in step two, directly remove the pressure transmitter and do a good job in protection; the backflush nitrogen pipeline includes 14 backflush nitrogen branch pipelines, the 14 backflush nitrogen branch pipelines are evenly distributed and connected to the nozzle of the silicon powder filter head in the form of flanges, and a root valve is provided at each nozzle of the silicon powder filter head, and all the root valves are removed; a valve and two spring hangers are provided on the vertical pipe section of the material outlet pipeline, and a portal bracket is fabricated to support at the flange position at the bottom of the valve to prevent the spring of the spring hanger from not resetting after removing the flange bolt, and remove the flange bolt to complete the disconnection of the material outlet pipeline from the silicon powder filter head.

[0018] Further, in step three, measure the flange surface gap with a vernier caliper before and after removing the bolts at the flange of the silicon powder filter head, and conduct grouped comparison and within-group comparison on the measurement data. If there is obvious deformation, re-machine the flange surface.

[0019] Further, in step six, when flushing with clean water, flush until the chloride ion content in the water does not exceed 25 mg / L.

[0020] Further, in step eight, four lifting points are used during hoisting, two of the lifting points use wire ropes and the other two use chain hoists, and the wire ropes and chain hoists are used symmetrically; during hoisting, adjust the surface level of the tube sheet through the chain hoist to effectively reduce the damage to the filter element caused by the collision between the filter element and the filter element disassembly and assembly bearing tool and the internal elements of the silicon powder filter due to inclination.

[0021] Further, both the steel columns and the main steel beams are derusted, and the derusting standard is Sa2.0 level; after derusting the steel columns and the main steel beams, apply 1 coat of polyurethane primer and 2 coats of polyurethane enamel intermediate paint first. After all the steel columns and the main steel beams are installed, conduct local repair on them and then spray 2 coats of polyurethane clear topcoat. The total dry film thickness is not less than 125 microns finally.

[0022] Further, in step four, the edge of the tube sheet in the filter element is supported on the load-bearing beam, and there is a gap of not less than 50 mm between the outer edge of the outermost filter element and the load-bearing beam.

[0023] Further, a 5-mm-thick rubber plate is provided on the upper surface of the load-bearing beam, and a 20-mm-thick foam board is provided on the inner side surface of the load-bearing beam.

[0024] Compared with the prior art, the method of the present invention is based on the external shape structure, structural distribution, etc. of the filter element of the silicon powder filter. At the same time, according to the characteristics such as the position of the silicon powder filter in the frame, the weight of the internal parts, and the entry and exit of the manhole at the top, the innovative technical solutions such as the exclusive supporting disassembly method, lifting method, and auxiliary disassembly and assembly bearing tool are finally determined, making the disassembly and assembly of the silicon powder filter, the maintenance and replacement of the filter element and other processes more convenient and fast, time-saving and labor-saving, greatly improving the disassembly, replacement, and maintenance efficiency of the silicon powder filter, thus saving the construction period. While improving the work efficiency, the method of the present invention also saves the usage fees of labor and machinery, reduces the maintenance cost, and creates certain economic value for the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings herein are used to provide further illustration of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0026] Figure 1 It is a schematic internal structure diagram of the silicon powder filter.

[0027] Figure 2 It is a top view of the structure of the tube sheet in the silicon powder filter.

[0028] Figure 3 It is a three-dimensional structure diagram of the disassembly and assembly bearing tool for the filter element.

[0029] Figure 4 It is a front view of the structure of the disassembly and assembly bearing tool for the filter element.

[0030] Figure 5 It is a top view of the structure of the platform part in the disassembly and assembly bearing tool for the filter element.

[0031] In the figure: 1 - pressure plate, 2 - tube sheet, 3 - pull frame, 4 - pull rod, 5 - filter element, 6 - support hole, 7 - steel column, 8 - main steel beam, 9 - load-bearing beam, 10 - cage straight ladder, 11 - high fence, 12 - diamond plate, 13 - reserved hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to enable those skilled in the art to better understand the present invention, the present invention will be further clearly and completely described below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of this application can be combined with each other. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In this embodiment, a certain high-purity polysilicon project is taken as an example. The tail gas recovery section is a steel structure frame, which is divided into four layers. The elevations of each layer are EL+0m, EL+8.0m, EL+15.0m, and EL+19.5m respectively for the plant building, and the installation elevation of the silicon powder filter is EL+15.0m. There are a total of 6 silicon powder filters in the tail gas recovery section. The equipment specifications are φ2500mm×8760mm, with a circular upper part and a conical bottom. The single-unit weight is 29 tons, and the single-unit weight of the filter element is 7.2 tons.

[0034] This embodiment provides a method for maintaining and replacing the filter element of the silicon powder filter in the above project, which specifically includes the following steps: Step 1, fabricate a loading and unloading carrier for the filter element. As Figure 1 and Figure 2 shown, the filter element is mainly composed of a pressing plate 1, a tube plate 2, a pulling frame 3, a pull rod 4, and a filter element 5. According to its external shape structure and structural distribution characteristics, fabricate a loading and unloading carrier for the filter element specifically used for supporting and disassembling the filter element. As Figures 3 to 5As shown in the figure, the disassembly and assembly bearing tool for the filter element adopts a steel structure frame made of steel members, which has the characteristics of light weight, high strength, high efficiency, corrosion resistance, and reusability. The steel structure frame includes a support part and a platform part. The platform part is fixed at the top of the support part, and a support hole 6 is reserved at the center position of the platform part. Specifically, the support part consists of four steel columns 7, and the platform part adopts a cantilever platform. The selected cantilever platform conforms to the XTJ-10-1 type in HG / T21543.42-2009. The elevation of the cantilever platform is EL3300. The cantilever platform is fixedly connected by multiple main steel beams 8 that crisscross vertically and horizontally. A square support hole 6 is reserved at the center position of the cantilever platform, and four load-bearing beams 9 for supporting the filter element are fixedly connected between the main steel beams 8 around the support hole 6. The four load-bearing beams 9 are respectively located at the four corners of the support hole 6, and the four load-bearing beams 9 are centrosymmetrically arranged with the center of the support hole 6 as the center. A cage straight ladder 10 is fixed on one side of the platform part, and the selected cage straight ladder 10 conforms to the positive access straight ladder in HG / T21543.30-2009. High fences 11 are fixed around the platform part, and the height of the high fences 11 is 1250 mm. The top surface of the platform part is covered and fixed with diamond pattern steel plates 12, and the thickness of the diamond pattern steel plates 12 is 6 mm. A reserved hole 13 adapted to it is also opened at the position of the support hole 6 on the diamond pattern steel plates 12, and the size of the reserved hole 13 is Φ2400 mm, so as to ensure that the filter element 5 can pass through smoothly as a whole while the tube sheet 2 can still be supported on the load-bearing beam 9. The length of the above-mentioned filter element is 2700 mm, so the designed height of the disassembly and assembly bearing tool for the filter element is 3300 mm. The height of the disassembly and assembly bearing tool for the filter element is 600 mm higher than the filter element 5, and enough working space is reserved at the lower part to facilitate the tightening of the bolts of the pull box 3 in the filter element.

[0035] The construction of the above-mentioned disassembly and assembly bearing tool for the filter element specifically includes: 1) Preliminary preparation: including construction preparation and formulation of safety measures; construction preparation includes site cleaning, road widening, layout of the construction site and equipment, etc., while safety measures include labor protection, scaffolding erection, power supply guarantee, etc.

[0036] 2) Fabrication of the steel structure frame: First, the steel materials need to be precisely fabricated according to the design drawings, and then cut, drilled and cut according to the standard length and specifications. After that, the processed steel materials need to be formed and welded, and the welding quality needs to be strictly controlled to ensure the firmness of the structure.

[0037] 3) On-site assembly: Before on-site assembly, the construction site needs to be cleaned and leveled to ensure that the construction site is smooth and flat; after that, the beams, columns, ladders and railings are installed according to the construction drawings; during the assembly process, it is necessary to strictly construct according to the construction drawings and processes, and at the same time fully consider on-site safety and construction quality.

[0038] 4) Welding: The welding of the steel structure framework is a very crucial process. Professional welding equipment and techniques should be used for the welding of the steel structure framework to ensure welding strength and integrity, while avoiding adverse effects of welding temperature on the steel. The welding principles are as follows: When the structure is symmetrical, symmetric welding method is adopted; when the welds are concentrated, skip welding method is used to disperse the heat and avoid concentrated heat; for assembled components, after the component group welding and correction are qualified, then the overall assembly is carried out. When the structure is asymmetrical, the side with fewer welds is welded first; the welds with larger shrinkage amounts are welded first, enabling the welds to shrink more freely to minimize welding stress to the greatest extent; the welds that are more stressed during operation are welded first to make the internal stress reasonably distributed.

[0039] 5) Coating: Since the steel structure framework is for the use of the silicon powder filter element, and the silicon powder filter element belongs to special equipment, the anti-corrosion coating of the steel structure framework is also a very crucial process. When coating the steel structure framework, rust removal treatment is carried out first. The rust removal standard is Sa2.0 level. After rust removal of the steel structure framework, apply 1 coat of polyurethane primer and 2 coats of polyurethane enamel intermediate paint. After all the steel structure frameworks are installed, conduct local repair on it and then spray 2 coats of polyurethane clear topcoat. Finally, the total dry film thickness is not less than 125 microns.

[0040] Step 2: Remove the pipe fittings connected to the nozzle of the silicon powder filter head. The pipe fittings connected to the nozzle of the silicon powder filter head include: pressure transmitter, backflush nitrogen pipeline, and material outlet pipeline.

[0041] Directly remove the pressure transmitter and do a good job in protection; the backflush nitrogen pipeline includes 14 backflush nitrogen branch pipelines. The 14 backflush nitrogen branch pipelines are evenly distributed and connected to the nozzle of the silicon powder filter head in the form of flanges. A root valve is set at each nozzle of the silicon powder filter head, and all the root valves are removed; there is a valve weighing about 5 tons on the vertical pipe section of the material outlet pipeline, and there are only two spring hangers on the vertical pipe section. Therefore, make a portal support to support at the flange position at the bottom of the valve to prevent the spring of the spring hanger from not resetting after removing the flange bolt. Remove the flange bolt to complete the disconnection of the material outlet pipeline from the silicon powder filter head.

[0042] Step 3: Remove the silicon powder filter head. Use a paint pen to make 2 - 3 marking lines at the flange positions of the silicon powder filter head flange and the silicon powder filter cylinder flange, evenly distributed, and remove all the bolts at the flange. Use a crane to lift the silicon powder filter head to the pre-prepared sleepers for placement. The height of the sleepers is not less than 200 mm.

[0043] The head flange and the shell flange are made of 16MnⅣ + surfacing S31603. The internal welding stress is likely to cause deformation of the flange, resulting in poor sealing. Therefore, before and after removing the bolts at the head flange part of the silicon powder filter, the clearance of the flange surface is measured with a vernier caliper, and the measured data is grouped and compared within the group. If there is obvious deformation, the flange surface is machined again.

[0044] Step Four: Remove the filter element as a whole. The filter element mainly consists of a pressing plate 1, a tube sheet 2, a pulling frame 3, a pulling rod 4, and filter elements 5. First, all the fixing bolts between the tube sheet 2 and the supporting ring plate inside the silicon powder filter are removed, and the filter element is hoisted out as a whole and placed on a pre-prepared disassembly and assembly bearing tool for the filter element. The filter element is stably supported at the supporting hole 6 of the disassembly and assembly bearing tool for the filter element. During this process, a 5-mm-thick rubber plate is arranged on the upper surface of the load-bearing beam 9, and a 20-mm-thick foam board is arranged on the inner side surface of the load-bearing beam 9 to prevent damage to the sealing surface of the tube sheet 2 and damage to the surface coating of the filter element 5 during hoisting. The edge of the tube sheet 2 in the filter element is supported on the load-bearing beam 9, and there is a gap of not less than 50 mm between the outer edge of the outermost filter element 5 and the load-bearing beam 9. The disassembly and assembly bearing tool for the filter element is placed on the horizontal ground, and the site needs to be spacious enough for stacking materials such as tubular filter elements 5.

[0045] Step Five: Remove the filter element 5. On the disassembly and assembly bearing tool for the filter element, the number of filter elements 5 for a single filter element is 336 (as Figure 2 shown), the number of fixing bolts for the pressing plate 1 is 912, and the number of fixing bolts for the pulling frame 3 is 528. First, all the bolts on the pressing plate 1 and the pulling frame 3 are removed, and the removed bolts are placed in a wooden box to prevent loss. Then, the filter elements 5 are taken out from bottom to top and transported out of the site to prevent mixing with the new filter elements 5.

[0046] Step Six: Clean the tube sheet 2. On the disassembly and assembly bearing tool for the filter element, the tube sheet 2 is pickled with pickling paste, and then rinsed with clean water until the chloride ion content in the water does not exceed 25 mg / L. Finally, it is dried with clean air.

[0047] Step Seven: Install new filter elements 5. When installing the filter elements 5, the construction personnel are cleanly dressed and wear dust-proof shoe covers and white gloves for construction operations. On the disassembly and assembly bearing tool for the filter element, first, cotton gauze is laid on the upper edge and inner surface of the tube orifice of the tube sheet 2, and the new filter elements 5 are installed one by one from top to bottom through the tube orifices of the tube sheet 2. The bottom bolts of the filter elements 5 are correspondingly inserted into the bolt holes of the pulling frame 3. The filter elements 5 are divided into 14 groups (as Figure 2 shown). After each group is filled, the pressing plate 1 is installed in place and the bolts are tightened, and all the bolts of the pulling frame 3 are tightened, and the assembly of the filter element is completed.

[0048] Step 8: Reinstall the entire filter element. Lift the assembled filter element into place and complete the installation using a crane; when lifting, use four lifting points, with two lifting points using wire ropes and the other two using chain hoists, and the wire ropes and chain hoists are used symmetrically; when lifting, adjust the level of the tube sheet 2 through the chain hoist to effectively reduce the damage to the filter element caused by the collision between the filter element and the filter element disassembly and assembly load-bearing tool and the internal components of the silicon powder filter due to inclination.

[0049] Lifting calculation: Select a 200-ton truck-mounted crane at the station crane position, with an operating radius of 30 - 38 meters, a boom length of 43 - 54 meters, and the lifting capacity of the filter element is 7.2 tons.

[0050] 1) Lifting load of the filter element P = K1*(Q + q) = 1.1*(7.2 + 0.5) = 8.47t Where: K1 is the dynamic load coefficient, taking 1.1; Q is the self-weight of the filter element; q is the weight of the hook and rigging, and the weight of the hook and rigging is 0.5t; Select a 200T truck-mounted crane, with a boom length of 52m, a slewing radius of 36m, and an elevation angle of 45°. Its rated load P' = 9.8t, and the lifting height H' = 52*sin45 = 36m > 28.3m (the top elevation of the filter element). Since P < P', the load-bearing situation of the crane is P' / P = 8.47 / 9.8 = 86.4%, so the 200T truck crane can meet the usage requirements.

[0051] 2) Rigging equipment ① Selection of wire rope for hanging the filter element Force on the main lifting wire rope (using 2 roots of 1-bend 2-strand ropes) S = Q / 2 = 8.47 / 2 = 4.235T Then the breaking force of a single wire rope P = K•S = 4.235×10×6 = 254.1KN Safety factor k = 6 ② Check the wire rope table (GB8918 - 2006) and select a fiber core wire rope 6×37 - 1570 - Φ26, whose breaking force is 350KN > 254.1KN, which can meet the requirements.

[0052] Step 9: Reinstall the head of the silicon powder filter and restore the pipe fittings connected to the pipe orifices; When reinstalling the head of the silicon powder filter, reinstall it according to the marked line position drawn before disassembly, and tighten all the bolts.

[0053] The above-described embodiments merely represent the optimal implementation modes of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A method for maintaining and replacing a filter element of a silicon powder filter, characterized in that: The steps include: Step 1: making a filter element disassembly and assembly support jig; The filter element disassembly and assembly support jig adopts a steel structure frame made of steel components. The steel structure frame includes a support part and a platform part. The platform part is fixed on the top of the support part, and a support hole is reserved at the center of the platform part. Step 2: Remove the pipe fittings connected to the pipe opening of the silicon powder filter head; The pipe fittings connected to the silicon powder filter head pipe port include: pressure transmitter, backflush nitrogen pipeline, material outlet pipeline; Step 3, dismantling the silicon powder filter head; Use a paint pen to make 2-3 marking lines on the flange of the silicon powder filter head and the flange of the silicon powder filter cylinder, evenly distribute them, and remove all the bolts at the flange. Use a crane to lift the silicon powder filter head to the prepared sleepers, and place them on the sleepers. The height of the sleepers should not be less than 200mm. Step 4, dismantle the filter element as a whole; The filter element is mainly composed of a pressing plate, a tube sheet, a pull frame, a pull rod, and a filter element. First, remove all the fixing bolts between the tube sheet and the supporting ring plate in the silicon powder filter, lift the filter element as a whole and place it on the filter element disassembly and assembly support jig prepared in advance. The filter element is firmly supported at the support holes on the filter element disassembly and assembly support jig; Step 5: Remove the filter element; On the filter element disassembly and assembly jig, first remove all the bolts on the pressure plate and the pull frame, and place the removed bolts in a wooden box to prevent loss; then take out the filter element from bottom to top and transport it out of the site to prevent it from being mixed with the new filter element; Step six, cleaning the tube sheet; On the filter element disassembly and assembly jig, use pickling paste to pickle the tube sheet, then rinse it with clean water, and finally blow it dry with clean air; Step 7: Install the new filter element; On the filter element disassembly and assembly support jig, first lay cotton gauze on the upper edge and inner surface of the tube sheet orifice, install the new filter element one by one through the tube sheet orifice from top to bottom, and insert the bolts at the bottom of the filter element into the bolt holes of the pull frame accordingly. After the filling is completed, install the pressure plate in place, tighten the bolts, tighten all the pull frame bolts, and the filter element is assembled; Step 8: Reinstall the filter element as a whole; Use a crane to hoist the assembled filter element into place and complete the installation; Step nine, reinstall the silicon powder filter head and restore the pipe fittings connected to the pipe mouth; When reinstalling the head of the silicon powder filter, reinstall it according to the position of the marked line drawn before removal and tighten all the bolts.

2. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 1, characterized in that: In step one, the support part is composed of four steel columns, the platform part is connected and fixed by multiple criss-crossed main steel beams, and multiple load-bearing beams for supporting the filter elements are fixedly connected between the main steel beams located in a circle of supporting holes; a cage ladder is fixed on one side of the platform part, and high fences are fixed around the platform part. The top surface of the platform part is covered and fixed with a patterned steel plate, and reserved holes corresponding to the support holes are also opened on the patterned steel plate.

3. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 1, characterized in that: In step 2, the pressure transmitter is directly removed and protected; the backflush nitrogen pipeline includes 14 backflush nitrogen branch pipelines, which are evenly distributed and connected to the silicon powder filter head pipe port through flanges. Each silicon powder filter head pipe port is provided with a root valve, and all the root valves are removed; a valve and two spring hangers are provided on the vertical pipe section of the material outlet pipeline, and a door-type bracket is made to support the flange position at the bottom of the valve to prevent the spring of the spring hanger from being unable to reset after the flange mouth bolts are removed. The flange mouth bolts are removed to complete the disconnection of the material outlet pipeline and the silicon powder filter head.

4. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 1, characterized in that: In step three, the flange surface clearance is measured with a vernier caliper before and after removing the bolts at the flange of the silicon powder filter head, and the measurement data are compared in groups and within groups. If there is obvious deformation, the flange surface is re-machined.

5. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 1, characterized in that: In step 6, when flushing with clean water, flush until the chloride ion content in the water does not exceed 25 mg / L.

6. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 1, characterized in that: In step eight, four lifting points are used for hoisting, two of which use wire ropes and the other two use hand hoists, and the wire ropes and hand hoists are used symmetrically; when lifting, the hand hoists are used to adjust the surface level of the tube sheet to effectively reduce the damage to the filter element caused by the collision of the filter element disassembly and assembly bearing jig and the internal components of the silicon powder filter due to the tilt of the filter element.

7. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 2, characterized in that: The steel columns and main steel beams are all derusted, and the rust removal standard is Sa2.0 level; after derusting, the steel columns and main steel beams are first coated with one coat of polyurethane primer and two coats of polyurethane magnetic paint intermediate paint. After the steel columns and main steel beams are all installed, they are partially repaired and then sprayed with two coats of polyurethane varnish topcoat. The final total thickness of the dry paint film is not less than 125 microns.

8. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 2, characterized in that: In step 4, the edge of the tube sheet in the filter element is supported on the load-bearing beam, and a gap of not less than 50 mm is left between the outer edge of the outermost filter element and the load-bearing beam.

9. The method for maintaining and replacing the filter element of the silicon powder filter according to claim 8, characterized in that: The upper surface of the load-bearing beam is provided with a 5mm thick rubber plate, and the inner side surface of the load-bearing beam is provided with a 20mm thick foam plate.

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