A method for overhauling an air preheater

Abstract

The application provides a kind of overhauling method of air preheater, comprising the following steps: carrying out shutdown operation, opening all maintenance doors for ventilation after confirming shutdown, and removing the insulation layer of cold end element and hot end element installation position until cooling to preset temperature;Obtain various data of air preheater at initial state when stopping;According to the position data of cold end element and hot end element, open replacement hole for cold end element and hot end element disassembly, and remove radial sealing sheet and pressing plate of hot end in advance;Open hoisting opening on air preheater, remove hot end element and cold end element and hoist to move to hoisting opening position;Erect working platform, hoist hot end element and cold end element hoisted to zero meter ground to hoisting opening position.The application measures the parameters of each original element in advance before disassembly, and installs according to the parameters in advance after maintenance, to avoid that the air preheater after maintenance cannot work normally, and the maintenance method is simple and fast.

Description

Technical Field

[0001] The present invention relates to the technical field of air preheaters, and in particular to a maintenance method for an air preheater. Background Art

[0002] An air preheater is a device that preheats the flue gas from the boiler's tail flue to a certain temperature before entering the boiler through heat exchange fins inside the air preheater. This improves the boiler's heat exchange performance and reduces energy consumption. Air preheaters are generally classified into three types: plate, rotary, and tubular.

[0003] Existing air preheaters need to be inspected and maintained after a period of use. The current inspection and maintenance methods are complicated and messy, which can easily lead to inconsistent parameters after inspection, thereby affecting the normal use of the air preheater. Summary of the Invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a maintenance method for an air preheater.

[0005] According to the present invention, a method for repairing an air preheater includes the following steps:

[0006] Carry out the furnace shutdown operation. After confirming the furnace shutdown, open all inspection doors for ventilation and remove the insulation layer at the installation location of the cold end components and hot end components until the furnace cools to the preset temperature;

[0007] Obtain the axial seal gap, radial seal gap, annular seal gap, wear and damage of each seal, and the position and levelness data of the cold-end and hot-end components in the initial state when the air preheater is stopped;

[0008] According to the location data of the cold end components and the hot end components, replacement holes for disassembly of the cold end components and the hot end components are opened, and the radial sealing sheet and the pressure plate of the hot end are removed in advance;

[0009] Open a lifting port on the air preheater, remove the hot end components and cold end components, and lift them to the lifting port;

[0010] Set up a working platform, hoist the hot end components and the cold end components moved to the hoisting port position onto the working platform, and then hoist them from the working platform to zero meters on the ground;

[0011] The hot-end components and cold-end components that have been lifted out are inspected and replaced, and the inspected and replaced cold-end components and hot-end components are reassembled according to the pre-acquired data, the replacement holes are restored, and the insulation layer at the replacement hole locations is reassembled.

[0012] Optionally, the step of removing the hot-end component and the cold-end component and hoisting and moving them to the hoisting port further includes:

[0013] From the inner ring to the outer ring, the hot-end components and the cold-end components are hoisted out in a 180° symmetrical manner. After hoisting two adjacent components to the lifting port, turn the machine 180° and then hoist the component boxes corresponding to the two adjacent components to the lifting port symmetrically 180°.

[0014] Optionally, the setting up of the working platform, hoisting the hot end component and the cold end component moved to the hoisting opening position onto the working platform, and then hoisting them from the working platform to zero meters above the ground, further comprises:

[0015] A working platform is set up at the hoisting passage between the two air preheaters, and the working platform is close to the hoisting openings of the two air preheaters;

[0016] The hot end component and the cold end component are hoisted out from the hoisting port to the working platform, and then the hot end component and the cold end component are moved to a preset position on the platform, and then hoisted from the working platform to zero meters ground.

[0017] Optionally, after reassembling the repaired and replaced cold-end components and hot-end components according to the pre-acquired data, a rotor calibration process is further included, which further includes:

[0018] When the cold-end element and the hot-end element are in a loaded state, open the guide bearing top cover and packing of the rotor, and use a feeler gauge to measure on the cold-end sector plate to ensure that the horizontal accuracy of the cold-end element and the hot-end element is within the preset accuracy range;

[0019] Adjust the annular seal of the cold end component and the hot end component to ensure that the annular seal gap of the cold end component and the hot end component in the heated state is within the preset annular seal gap range.

[0020] Optionally, the air preheater transmission device overhaul is also included, which further includes:

[0021] Remove the cover door under the support frame assembly, loosen the two bolts at the shaft end by 2 to 3 mm, or set up temporary supports at the preset position to prevent the large gear from falling;

[0022] Unscrew the fastening bolts, use the supporting screw holes on the elastic sleeve to support the end face of the large gear with bolts to disengage the elastic sleeve from the large gear;

[0023] Check the lower belt and large gear of the air preheater and decide on the treatment plan based on the wear condition.

[0024] Optionally, after the transmission device of the air preheater is overhauled, the assembly process of the transmission device further includes:

[0025] Clean and inspect the joint surfaces of the installed parts and flatten the protrusions on the conical surface;

[0026] Reinstall the large gear and elastic sleeve, and install the end plate in time.

[0027] Optionally, find the highest point on the upper end surface of the lower shroud flat steel and mark it, find the most protruding point on the outer edge of the shroud pin and mark it;

[0028] Adjust the distance between the highest point of the upper end surface of the lower shroud flat steel and the lower end surface of the large gear to a first preset distance, and adjust the distance between the most protruding point of the outer edge of the shroud pin and the tooth root of the large gear to a second preset distance;

[0029] Apply grease to the fastening bolts, then tighten the large gear and elastic sleeve;

[0030] During the cold test run, check the meshing marks between the pin and the wheel, and adjust the reduction gearbox so that the meshing surface between the shroud pin and the large gear is even;

[0031] Review the first preset distance and the second preset distance. When the first preset distance and the second preset distance are met, tighten the bolts to the specified torque, install other parts, cover the cover and wait for operation.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides an air preheater maintenance method, which measures the parameters of each component before disassembly and installs it according to the preset parameters after maintenance, thereby avoiding the air preheater from malfunctioning after maintenance, and the maintenance method is simple and quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0035] Figure 1 A flow chart of the method for repairing an air preheater provided by the present invention;

[0036] Figure 2 A schematic diagram of the hoisting principle of the air preheater maintenance method provided by the present invention;

[0037] Figure 3 A schematic diagram of the large gear disassembly principle of the air preheater maintenance method provided by the present invention;

[0038] Figure 4 This is a large gear assembly diagram of the air preheater maintenance method provided by the present invention. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0040] It is known that before maintenance, corresponding preparations and conditions need to be made, including:

[0041] 1.1 Select a temporary storage site for the preheater dismantled parts and new equipment (the temporary storage site is selected next to the fan and chimney), and arrange the construction power supply, welding machine, and other facilities.

[0042] 1.2 For the equipment that arrives at the site, check and count them against the drawings and equipment list, unpack and inspect them, and number them. Re-measure the dimensions of the main equipment such as component boxes, check the accessories, and keep records. Keep them properly stored, place them in a fixed location, and collect the accompanying documents.

[0043] Determine the opening location for dismantling and installing the heat transfer element, and set up a rack for dismantling and installing.

[0044] 1.3 Plan for the entry of major construction machinery and tools:

[0045] Special equipment and electrical machinery must pass inspection and testing before they can enter the site.

[0046] Figure 1 The flow chart of the maintenance method of the air preheater provided by the present invention is as follows: Figure 1 As shown, the following steps are included:

[0047] S1, perform the furnace shutdown operation. After confirming the furnace shutdown, open all maintenance doors for ventilation and remove the insulation layer at the installation location of the cold end components and the hot end components until it cools to the preset temperature, which is generally below 50°C;

[0048] S2, obtaining the axial sealing gap, radial sealing gap, annular sealing gap, wear and damage of each seal, and position and levelness data of the cold-end component and the hot-end component in the initial state when the air preheater is stopped;

[0049] S3, opening replacement holes for disassembling the cold-end component and the hot-end component according to the position data of the cold-end component and the hot-end component, and removing the radial sealing sheet and the pressure plate of the hot-end in advance;

[0050] S4, open a lifting port on the air preheater. The lifting port is generally opened above the rotor guard plate of the air preheater shell. Remove the hot end component and the cold end component and lift them to the lifting port.

[0051] S5, set up the working platform, hoist the hot end components and cold end components that have been moved to the hoisting port onto the working platform, and then hoist them from the working platform to the zero-meter ground;

[0052] S6, repair and replace the hot end components and cold end components that have been lifted out, reassemble the repaired and replaced cold end components and hot end components according to the pre-acquired data, restore the replacement holes, and reassemble the insulation layer at the replacement hole locations.

[0053] See also Figure 2 , removing the hot end components and the cold end components and hoisting them to the hoisting port position, further comprising:

[0054] From the inner ring to the outer ring, the hot-end components and the cold-end components are hoisted out 180° symmetrically. Since the hot-end components are above the cold-end components, the hot-end components are hoisted out first using the above method, and then the cold-end components are hoisted out. After hoisting the two adjacent compartments to the hoisting port, they are rotated 180° and then hoisted out the component boxes corresponding to the two adjacent compartments 180° symmetrically to the hoisting port. It can be understood that the so-called from the inner ring to the outer ring, that is, the compartments are generally spliced ​​by blocks, so when hoisting, the blocks of the inner ring will be hoisted out first, and then the blocks of the outer ring will be hoisted out The so-called 180° symmetrical lifting ring by ring means lifting out one of the cells first, then lifting out the second cell that is symmetrical to it after rotating it 180°, then lifting out the third cell adjacent to the second cell, and then lifting out the fourth cell that is symmetrical to the third cell after rotating it 180°. Repeat the above steps until all cells are lifted out. The above lifting method will not cause the problem of excessive weight on one side during the lifting process, causing the overall structure of the hot end component to be skewed, and will never cause irreversible damage. Therefore, it is necessary to lift out the components symmetrically 180° from the inner ring to the outer ring, such as Figure 2 The order should be followed to keep the force evenly distributed during the process. The method of hoisting to the hoisting port can be to set up a monorail crane (2 tons) on the flue gas side of each air preheater, about 6 meters away from the top of the hot end component. The moving range of the hook and the lifting height should be taken into consideration. Through the above-mentioned hoisting method, the hot end components can be prevented from being subjected to irreversible deformation, thereby avoiding affecting the service life of the rotor bearings.

[0055] Moreover, in order to further improve the stability of lifting, the lifting process of the hot end component further includes:

[0056] Setting up a working platform, hoisting the hot end components and the cold end components moved to the hoisting opening position onto the working platform, and then hoisting them from the working platform to zero meters on the ground, further including:

[0057] Set up a working platform at the hoisting passage between the two air preheaters, and the working platform should be close to the hoisting openings of the two air preheaters;

[0058] Lift the hot-end components and the cold-end components from the lifting port to the working platform, then move the hot-end components and the cold-end components on the platform to the preset position, and then lift them from the working platform to the zero-meter ground. It can be known that the working platform generally includes a 33-meter-high working platform. Although the height of the air preheater is generally more than ten meters, the height of the assembly location is generally higher. Therefore, lifting to a 33-meter-high working platform is actually falling to a 33-meter-high working platform and lifting from a 33-meter-high working platform to the zero-meter ground. Generally, a steel beam is set up near the working platform, and then an electric hoist is installed on the top of the steel beam, and the winch equipment is used to lift the hot-end components at the working platform to the zero-meter ground. During lifting, the compartment of the hot-end component should be aligned with the center line of the electric hoist track, and then moved to the top of the zero-meter ground and dropped to the zero-meter ground through the winch equipment.

[0059] Note: The above method can also be used to hoist cold-end components. The cold-end component box is heavy. If the original welds are worn, rusted, or cracked, they should be prevented from falling during the lifting process. Binding should be used when lifting from the platform to the ground. When removing components, they should be removed symmetrically or at intervals to prevent the rotor from overweight and damaging the equipment, which would increase the difficulty of installation and turning.

[0060] In this embodiment, after the original parts are reassembled, a rotor calibration process is also included, which further includes:

[0061] After reassembling the repaired and replaced cold-end components and hot-end components according to the pre-acquired data, the rotor calibration process further includes;

[0062] Levelness check: When the cold-end and hot-end components are under load, open the rotor guide bearing cover and packing, and use a feeler gauge to measure on the cold-end sector plate to ensure that the level accuracy of the cold-end and hot-end components is within the preset accuracy range;

[0063] Verticality check: Adjust the annular seal of the cold end component and the hot end component to ensure that the annular seal gap of the cold end component and the hot end component in the heated state is within the preset annular seal gap range;

[0064] Roundness check: Use a horizontal level hose gauge to measure the distance between four points around the rotor and the inner wall of the air preheater to ensure that the deviation is less than the preset deviation value.

[0065] See also Figure 3 It is known that the air preheater transmission device overhaul is also included, which further includes:

[0066] Also included is an air preheater transmission overhaul, which further includes:

[0067] Remove the cover door under the support frame assembly, loosen the two bolts at the shaft end by 2 to 3 mm, or set up temporary supports at the preset position to prevent the large gear from falling;

[0068] Unscrew the fastening bolts, use the supporting screw holes on the elastic sleeve to support the end face of the large gear with bolts to disengage the elastic sleeve from the large gear;

[0069] Check the lower belt and large gear of the air preheater and decide on the treatment plan based on the wear condition. If the wear exceeds 3.5mm, it must be replaced; if it is less than 3.5mm, it can continue to be used.

[0070] On the basis of the above scheme, after the air preheater transmission device is overhauled, the assembly process of the transmission device further includes:

[0071] Clean and inspect the joint surfaces of the installed parts and flatten the protrusions on the conical surface;

[0072] Reinstall the large gear and elastic sleeve, and install the end plate in time.

[0073] See also Figure 4 , the reassembly process of the large gear further includes:

[0074] Find the highest point on the upper end of the lower belt flat steel and mark it, find the most protruding point on the outer edge of the belt pin and mark it;

[0075] Adjust the distance between the highest point of the upper end surface of the lower belt flat steel and the lower end surface of the large gear to the first preset distance. The first preset distance is Figure 4 a in the figure, adjust the distance between the most protruding point of the outer edge of the shroud pin and the tooth root of the large gear to the second preset distance, which is Figure 4 b in;

[0076] Apply grease to the fastening bolts, then tighten the large gear and elastic sleeve;

[0077] During the cold test run, check the meshing marks between the pin and the wheel, and adjust the reduction gearbox so that the meshing surface between the shroud pin and the large gear is even;

[0078] Review the first preset distance and the second preset distance. If they meet the requirements, tighten the bolts to the specified torque, install other parts, cover the cover and wait for operation. If they do not meet the requirements, readjust.

[0079] In addition to the above-mentioned overhaul process, the cold end sector plate automatic tracking device modification is also included:

[0080] Mechanical system installation:

[0081] Remove the fixing bolts on both sides of the six cold end sector plates and add hinges to the heads of the sector plates (near the center tube);

[0082] Remove the tail boom and boom fixing assembly of the cold end fan plate, replace with a new lifting rod, and install the sealing assembly;

[0083] Weld the base support assembly on the inner side of the cold end beam, install the lifting mechanism assembly, and connect the lifting assembly with the lifting rod;

[0084] Check and adjust the bottom hinge of the lifting mechanism, and adjust the sector plate to the cold zero position (the cold reserved gap position is the zero position);

[0085] Install the travel limit assembly and adjust the lower limit position of the fan plate. The upper limit position will be adjusted in the hot state. Install the gap sensor on the side (air side) of the fan plate. Lay the relevant air source pipeline;

[0086] Electrical system installation:

[0087] Install the relevant control cabinets in place according to the manufacturer's and electrical layout drawings, and lay the cables.

[0088] Cold and hot commissioning;

[0089] Cold installation and commissioning, hot commissioning.

[0090] Installation and adjustment of sealing sheet:

[0091] After the components are hoisted, install and adjust the sealing sheet;

[0092] Installation of hot and cold end radial seals:

[0093] (1) Install the steel beam and fix the radial seal setting rod;

[0094] (2) Manually crank the machine until a radial grid plate is aligned with the edge of the top or bottom sector plate plane, and adjust and secure the sealing piece according to the required clearance; after all the sealing pieces on the radial grid plate are adjusted and verified to be correct, crank the machine in the reverse direction to move the adjusted sealing piece to the position directly above or directly below the radial seal setting rod, and set the seal setting rod based on the sealing piece;

[0095] (3) Using the seal setting rod as a reference, adjust all the seals; after confirming that all the seals are correctly installed and all the screws are tightened correctly, remove the seal setting rod;

[0096] (4) Set the scale according to the installation gap requirements of the radial seal of the air preheater on site, and ensure that the standard piece slides lightly on the scale without any gap or friction;

[0097] (5) Install the sealing sheet along the upper and lower ends of the radial partition according to the set scale, and tighten it with self-locking bolts to ensure the expansion gap between it and the upper and lower middle beam sector plates;

[0098] (6) After all work is completed, debugging should be carried out in accordance with quality standards. Specific requirements are shown in the quality requirements section of this plan.

[0099] Installation of hot and cold end axial seals:

[0100] (1) Install the steel beam and fix the axial seal setting rod;

[0101] (2) Manually turn the machine until an axial grid plate is aligned with the edge of the arc plate plane, and adjust and fix the sealing piece according to the required gap; after all the sealing pieces on the axial grid plate are adjusted and verified to be correct, turn the machine in the reverse direction to move the adjusted sealing piece to the positive side of the axial seal setting rod, and set the seal setting rod based on the sealing piece;

[0102] (3) Using the seal setting rod as a reference, adjust all the seals; after confirming that all the seals are correctly installed and all the screws are tightened correctly, remove the seal setting rod;

[0103] (4) Set the scale according to the installation gap requirements of the axial sealing piece of the air preheater on site, and ensure that the standard piece slides lightly on the scale without any gap or friction;

[0104] (5) According to the set scale, install the sealing sheet along the upper and lower ends of the axial partition and tighten it with self-locking bolts to ensure the expansion gap between it and each arc plate.

[0105] Fire alarm and hot end LCS maintenance:

[0106] Maintenance of the fan plate tracking device at the hot end of the air preheater;

[0107] Check the levelness of the six fan-shaped plates at the hot end. Inspect the reducer, screw jack, and torque protection device of the lifting device. Replace damaged parts and add lubricating oil and grease. Check sensors and adjust limit switches. Clean the control cabinet and inspect components and circuits. Perform hot and cold commissioning after repair.

[0108] Infrared fire alarm device maintenance:

[0109] Check and clean the infrared probe, inspect and change the oil in the reducer and screw. Check the gearbox and limit switches. Perform hot and cold commissioning after repair.

[0110] Restore cutting hole and keep warm:

[0111] (1) All temporary openings shall be sealed and welded with steel plates, and all inspection holes and manholes shall be inspected and opened flexibly and tightly without leakage;

[0112] (2) Insulation restoration: After insulation, the materials, structure and exterior protection should meet the requirements to achieve the effect of heat insulation and aesthetics.

[0113] Temporary facilities and internal cleaning:

[0114] The electric hoist inside the air preheater, the dismantling of the scaffolding and the external cleaning of the site are carried out to ensure that the site is cleared after the work is completed and all materials are removed.

[0115] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for repairing an air preheater, characterized in that: The steps include: Carry out the furnace shutdown operation. After confirming the furnace shutdown, open all inspection doors for ventilation and remove the insulation layer at the installation location of the cold end components and hot end components until the furnace cools to the preset temperature; Obtain the axial seal gap, radial seal gap, annular seal gap, wear and damage of each seal, and the position and levelness data of the cold-end and hot-end components in the initial state when the air preheater is stopped; According to the location data of the cold end components and the hot end components, replacement holes for disassembly of the cold end components and the hot end components are opened, and the radial sealing sheet and the pressure plate of the hot end are removed in advance; Open a lifting port on the air preheater, remove the hot end components and cold end components, and lift them to the lifting port; Set up a working platform, hoist the hot end components and the cold end components moved to the hoisting port position onto the working platform, and then hoist them from the working platform to zero meters on the ground; The hot-end components and cold-end components that have been lifted out are inspected and replaced, and the inspected and replaced cold-end components and hot-end components are reassembled according to the pre-acquired data, the replacement holes are restored, and the insulation layer at the replacement hole locations is reassembled.

2. The air preheater maintenance method according to claim 1, characterized in that: The method of removing the hot end component and the cold end component and hoisting and moving them to the hoisting port further includes: From the inner ring to the outer ring, the hot-end components and the cold-end components are hoisted out in a 180° symmetrical manner. After hoisting two adjacent components to the lifting port, turn the machine 180° and then hoist the component boxes corresponding to the two adjacent components to the lifting port symmetrically 180°.

3. The air preheater maintenance method according to claim 1, characterized in that: The setting up of the working platform, hoisting the hot end component and the cold end component moved to the hoisting opening position to the working platform, and then hoisting them from the working platform to zero meters ground further includes: A working platform is set up at the hoisting passage between the two air preheaters, and the working platform is close to the hoisting openings of the two air preheaters; The hot end component and the cold end component are hoisted out from the hoisting port to the working platform, and then the hot end component and the cold end component are moved to a preset position on the platform, and then hoisted from the working platform to zero meters ground.

4. The air preheater maintenance method according to claim 1, characterized in that: After reassembling the repaired and replaced cold-end components and hot-end components according to the pre-acquired data, the rotor calibration process further includes; When the cold-end element and the hot-end element are in a loaded state, open the guide bearing top cover and packing of the rotor, and use a feeler gauge to measure on the cold-end sector plate to ensure that the horizontal accuracy of the cold-end element and the hot-end element is within the preset accuracy range; Adjust the annular seal of the cold end component and the hot end component to ensure that the annular seal gap of the cold end component and the hot end component in the heated state is within the preset annular seal gap range.

5. The air preheater maintenance method according to claim 1, characterized in that: Also included is an air preheater transmission overhaul, which further includes: Remove the cover door under the support frame assembly, loosen the two bolts at the shaft end by 2 to 3 mm, or set up temporary supports at the preset position to prevent the large gear from falling; Unscrew the fastening bolts, use the supporting screw holes on the elastic sleeve to support the end face of the large gear with bolts to disengage the elastic sleeve from the large gear; Check the lower belt and large gear of the air preheater and decide on the treatment plan based on the wear condition.

6. The air preheater maintenance method according to claim 5, characterized in that: After the transmission device of the air preheater is overhauled, the assembly process of the transmission device further includes: Clean and inspect the joint surfaces of the installed parts and flatten the protrusions on the conical surface; Reinstall the large gear and elastic sleeve, and install the end plate in time.

7. The air preheater maintenance method according to claim 5, characterized in that: The reassembly process of the large gear further includes: Find the highest point on the upper end of the lower belt flat steel and mark it, find the most protruding point on the outer edge of the belt pin and mark it; Adjust the distance between the highest point of the upper end surface of the lower shroud flat steel and the lower end surface of the large gear to a first preset distance, and adjust the distance between the most protruding point of the outer edge of the shroud pin and the tooth root of the large gear to a second preset distance; Apply grease to the fastening bolts, then tighten the large gear and elastic sleeve; During the cold test run, check the meshing marks between the pin and the wheel, and adjust the reduction gearbox so that the meshing surface between the shroud pin and the large gear is even; The first preset distance and the second preset distance are combined. When the first preset distance and the second preset distance are met, the bolts are tightened to reach the specified torque, and other parts are installed and the cover is closed for operation.

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