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The maintenance and maintenance of conventional boilers should pay attention to the following points

2020-09-22 09:35    page view:

Guide: 1. Routine maintenance 1. Daily work (1) Check the function of the water level regulator: whether it can automatically fill the water and stop the pump.

  1. Routine maintenance

  1. Daily work

  (1) Check the function of the water level regulator: whether it can automatically fill the water and stop the pump.

  (2) Inspection of flame monitoring.

  (3) Rotate, slide, lubricate the cam parts and wipe them.

  (4) Rinse the water level gauge 1-2 times (per shift), and operate according to the correct method until the water level gauge is flushed.

  (5) Discharge 1-2 times (per shift).

  2, regular work

  (1) Items to be checked every week

  1) To stop the furnace at ultra-low water level, perform a furnace shutdown test (press the button on the B3 board, it should be able to simulate a water shortage and stop the furnace), or blow the sewage to check the function of the furnace at ultra-low water level.

  2) The safety valve is manually opened once and reset quickly.

  3) The burner control system and the electric eye should be inspected. The photoelectric cell of the electric eye should be taken out by hand, and the furnace should be stopped within 1 second; and the electric eye should be wiped.

  4) Fill or replace valve packing; eliminate dripping.

  5) Tighten bolts everywhere, especially the gas pipeline system, and check for leaks when necessary.

  (2) Clean the filter on the gas pipeline once a month.

  (3) The following parts should be maintained every six months

  1) Check the pressure gauge and clean the gauge tube, add distilled water when resetting.

  2) Maintain the water level electrode, after pulling it out, sand it with fine sandpaper.

  3) To clean the flue, generally according to the exhaust temperature to decide whether to clean. Under normal circumstances, the exhaust gas temperature does not exceed 350°C (measured at the outlet of the boiler and the entrance of the flue). Too high means that the fouling has increased and the efficiency of the boiler has decreased, and it must be cleaned. The purpose of cleaning the flue is on the one hand for economic considerations, on the other hand it is also for safety considerations (the smoke fouling has poor heat conduction and is prone to local burnout). When cleaning and replacing asbestos gaskets, use the method of lap joints (to prevent fumes from running out), and apply graphite instead of lubricating oil.

  4) After boiler repair or annual inspection, check that the manhole, head hole, hand hole nut can not be loosened, and check the motor rotation direction (from the fan end, it rotates counterclockwise).

  (4) Check the safety valve once a year. Perform a comprehensive overhaul and maintenance of the boiler.

  2. Normally shut down the furnace

  (1) Stop the fire: first turn the small fire knob to the low fire position, and then turn off the burner.

  (2) Reduce steam pressure.

  (3) Sheung Shui to high water level.

  (4) Close the main steam valve.

  (5) Close the Sheung Shui Festival gate.

  (6) Close the gas throttle door.

  (7) Check whether the drain valve is closed and tight.

  (8) Turn off the main power switch.

  For the shutdown of the hot water boiler, the circulating pump cannot be stopped immediately after the burner is turned off.

  3. Handling of temporary power outages

  (1) Close the main steam valve.

  (2) Turn off the main power supply.

  Four, shutdown maintenance

  In order to make the boiler operate safely and economically, it is necessary to strengthen the maintenance of the boiler in daily use. This is also an important measure to prevent the reduction of thermal efficiency, and avoid deterioration of use conditions and boiler accidents.

  1, regular maintenance

  In use, scale and sludge are formed on the inner surface of the boiler, and combustion products adhere to the outer surface of the pyrotechnic tube. This will corrode the boiler body, reduce thermal efficiency, and endanger the safe operation of the boiler. To this end, it is necessary to strengthen boiler maintenance and management, work out an inspection plan, and put it into practice.

  2. Shut down the furnace for cleaning

  Before shutting down the boiler and inspecting it, thoroughly clean the inside and outside of the boiler.

  (1) Internal cleaning

  Internal cleaning operations can be mechanical cleaning or chemical cleaning. When the scale is thick or hard, use chemical cleaning first, then mechanical cleaning. When the chemical cleaning method is adopted, it must be strictly in accordance with national regulations to prevent corrosion damage to the boiler caused by random washing. Chemical cleaning should be carried out by a professional unit approved by the relevant department. The mechanical cleaning method is to remove limescale with tools such as a hammer. Inspection after boiler cleaning is a very important task. Ignoring this work may cause accidents during operation, so take it seriously.

  The inspection contents after internal cleaning are as follows:

  1. Whether the scale is cleaned thoroughly, especially whether there is scale residue in the place subject to high temperature.

  2. Check whether the water level gauge, pressure gauge, automatic control contact point and the entrance and exit of each connection pipe have been cleaned and whether they are blocked by debris.

  3. Are tools, bolts, etc. left in the boiler?

  4. Check whether the partition of the drum, the steam-water separator, etc., are installed in the correct position.

  5. Check the parts for corrosion and damage, and record the degree of damage if any.

  (2) External cleaning

  External cleaning is divided into manual cleaning and mechanical cleaning. When cleaning manually, use soot blowing method for pyrotechnic pipe groups and slits that are out of reach. In addition, the following special methods can also be used for boilers of different structures, but brick walls and refractory materials must not be wetted.

  1) Steam soaking method. After spraying with steam, the ash is removed.

  2) Water soaking method. After spraying with water, the ash is removed.

  3) Water washing method. Use a lot of PH=8-9 water for washing. With this method, it must be a structure suitable for washing without touching the refractory brick wall.

  4) There are other special cleaning methods such as sandblasting and steel ball spraying.

  After external cleaning, the following inspections should be made:

  1. Whether the cleaning of the outside of the heating surface is thorough, and whether soot and moss remain in the flue.

  2. Whether the damaged and loose parts of the brick wall have been repaired.

  3. Whether there is damage to the baffle or partition wall, which may cause a short circuit of the smoke.

  4. Whether the filling between the boiler body and the brick wall and the filling at the thermal expansion gap are well filled.

  5. Whether the thermal insulation protection measures for the exhaust pipe of the flue, the beam steel column, etc. are perfect.

  6. Whether the installation of the boiler body is defective, and whether the thermal expansion treatment is correct.

  7. Whether the spray direction and installation position of the soot blower are correct.

  8. Whether the frame, movable plate and pressure spring of the explosion-proof door are burnt or deformed. Whether the function of the movable board is normal.

  9. Whether the flue gate switch action is flexible.

  10. Whether the brick wall refractory material is affected by moisture.

  11. Whether there are any signs of leakage at the pipe joints, pipelines and supports of the boiler body.

  3, shutdown maintenance

  During the boiler shutdown, the surface of the heating surface absorbs moisture in the air to form a water film. The oxygen and iron in the water film react chemically to generate rust, which causes corrosion of the boiler. After the corroded boiler is put into operation, the rust will intensify the depth of corrosion and expand the corrosion area at high temperatures, and the iron oxide will continue to peel off, so as to shorten the service life of the boiler, and even seriously reduce the strength of the steel plate and cause an explosion. Therefore, doing a good job of shutting down the boiler is an essential measure to ensure the safe and economical operation of the boiler. Commonly used shutdown maintenance methods include pressure maintenance, dry maintenance, wet maintenance and aeration maintenance.

  (1) Pressure maintenance

  Pressure maintenance is generally applicable to boilers whose boiler shutdown period does not exceed one week. Using the residual pressure in the boiler to maintain 0.5MPa-0.1MPa, the boiler water temperature is slightly higher than 100℃, even if the boiler water does not contain oxygen, it can also prevent air from entering the drum. In order to maintain the temperature of the boiler water, a slight fire can be generated in the furnace regularly, or the boiler water can be heated by the steam of an adjacent boiler on a regular basis.

  (2) Wet maintenance

  Wet maintenance is generally applicable to boilers whose boiler shutdown period does not exceed one month. After the boiler is shut down, drain the boiler water, remove scale and soot, close all manholes, hand holes, valves, etc., and completely isolate it from the running boiler. Then add softened water to the lowest water level, and then use a special pump to inject the prepared alkaline protection solution into the boiler. The composition of the protective solution is: sodium hydroxide (also called caustic soda) added 8-10Kg per ton of pot water, or sodium carbonate (also called soda ash) added 20Kg per ton of pot water, or trisodium phosphate added per ton of water 20Kg. When the protection solution is fully injected, open the water supply valve and fill the boiler (including superheater and economizer) with softened water until the water emerges from the air valve, then close the air valve and the water supply valve, and turn on the special pump for water circulation. The solution is mixed well. The function of the protective solution is to gradually form a layer of alkaline water film on the heated surface of the boiler, thereby protecting the heated surface from oxidation and corrosion. During the entire maintenance period, the oven should be lighted regularly to keep the outside of the heating surface dry; the pump should be regularly opened for water circulation to make the concentration of the solution consistent; the solution should be tested regularly, if the alkalinity decreases, it should be added . Take anti-freezing measures in winter.

  (3) Dry maintenance

  Dry maintenance is suitable for the boiler that has been shut down for a long time, especially the heating hot water boiler that is out of service in summer. After the boiler is shut down, drain the boiler water, remove the scale and soot, close the steam pipe, the valve on the hot water supply pipe, the water supply pipe and the sewage pipe of the hot water boiler, or use a partition to block it, and other operating boilers Completely isolated. Then open the manhole to let the drum dry naturally. If the boiler room is humid, it is best to dry the boiler body, as well as the furnace wall and flue with low fire, and then add 2-3Kg per cubic meter of boiler volume with desiccant, such as massive calcium oxide, also known as quicklime, or without water Calcium chloride is added 2Kg per cubic meter of boiler volume, placed in the furnace on an open tray, and hoisted in the drum with a cloth bag to absorb moisture. Finally, close all manholes and hand holes to prevent humid air from entering the boiler. In the future, check whether the heating surface is corroded every half a month or so, and replace the failed desiccant in time.

  (4)Inflation maintenance

  Aeration maintenance is suitable for boilers that are out of service for a long time. Generally, nitrogen or ammonia in a steel cylinder is used to fill and maintain a pressure of 0.05-0.1MPa from the highest part of the boiler to force the heavier air to be discharged from the lowest part of the boiler, so that the metal does not come into contact with oxygen. After nitrogen is charged into the boiler, oxygen can be driven away, and because of its alkaline reaction, it is more beneficial to prevent oxygen corrosion.

  For boilers that have been out of service for a long time, the outside of the heating surface should be painted with anti-rust paint after the soot has been removed; the inside of the heating surface should be painted with boiler anti-corrosion paint after the scale is removed. The auxiliary equipment of the boiler should also be cleaned. The smooth metal surface should be oiled to prevent rust. The lubricating oil in the blower and induced draft fan should be drained. All movable parts should be rotated once a week to prevent rusting.

  All electric equipment should be maintained in accordance with regulations.

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