Boiler start-up scheme
First, check the inside of the boiler before operation, especially the newly installed or overhauled boiler. Before baking, the following inspections and preparations should be made:
1. Is there anything attached or forgotten to the drum and head?
2. Whether manholes and handholes are tightly sealed, replace gaskets and fasten them when necessary.
3. The cold trial run of the chain grate exceeds 48 hours, and the grate can't arch, which requires stable rotation. Tighten the weight 1000kg, and adjust the grate to prevent deviation.
4. The minimum gap between the movable grate piece and the side wall sealing block shall not be less than 4 mm. ..
5. The distance between the two sides of the grate shaft and the side plate at the chain shaft should be equal, and the teeth of the movable grate plate and the chain teeth should be good.
6. Check whether the grate plate is damaged and whether the grate shaft is bent.
7. Irrelevant sundries (such as bolts and nails) are not allowed on the grate surface.
8. The distance between the left and right sides of the coal gate and the grate surface is the same, so as to keep the thickness of coal seam equal, and the cover plate should be tight to prevent coal leakage from blocking the coal gate.
9. The air door and flue air door of each air chamber of the grate are flexible.
10. The steam drum, induced draft fan, slag extractor and water supply equipment shall be tested normally.
1 1. Whether the pipeline part is tight and complete.
12. Whether the economizer is tight and the flue gas passage is clear.
13. Are all bearing boxes and oil cups filled with lubricating oil or butter?
14. Whether the accessories are complete.
15. Hydrostatic test: first, open the exhaust valve to let the air in the boiler be discharged when supplying water. The water supply must be slow, and the water temperature should not be too high (below 50℃ in winter). During the test, if the ambient temperature is lower than 5℃, anti-freezing measures must be taken. The pressure should be increased slowly, not by electric centrifugal pump. When the water pressure rises to 1.3- 1.5 MPa, carefully check all the sealing parts connected with the boiler and header, such as manholes, handholes, pressure gauges, thermometers, flanges, fillers, etc., for leaks, then keep them under the test pressure for 20 minutes, and then drop them to the working pressure for inspection. During the inspection, the pressure should be kept constant.
16. Inspection of boiler accessories and their joints:
(1) Whether the pressure gauge and water level gauge are leaking, whether the elbow connecting pipe is abnormal, whether the safety valve is adjusted to the specified opening and discharging pressure, whether the drain valve is flexibly opened and closed, whether all valve fillers have enough adjustment space, and whether the drain pipe is abnormal.
(2) Whether the circuit and panel are normal and sensitive.
(3) Whether the water pump and motor are normal, whether the steering is correct, and the damping pad, packing seal and bearing lubrication.
(4) Whether the intake fan, induced draft fan and motor are normal.
(5) Whether there is chain breakage and serious wear when the slag extractor is idling.
(6) The operation and oil level of each gearbox and reducer are normal.
Second, the oven and boiler:
When there is no problem in the inspection of the main engine and auxiliary engine of the boiler, make sure that all the components have safe starting conditions, and then dry and boil the furnace.
1. Purpose: Because the brick walls and mortar joints of newly installed or overhauled boilers contain a lot of water, the water in the furnace walls and arches should be slowly dried to prevent the cracks in the furnace walls and arches from being deformed or even collapsed due to violent volume expansion. The purpose of the boiling furnace is to remove impurities and grease in the furnace. When boiling, add an appropriate amount of sodium hydroxide or trisodium phosphate solution (5%) into the furnace to make the boiler water alkaline and remove oil stains.
Step 2 prepare the oven
(1) The boiler and auxiliary equipment have all been assembled and passed the cold test and the water pressure test.
(2) After the furnace wall is bricked and insulated, all doors (front and rear oven doors, coal doors, etc.). ) Let it dry naturally for a while.
(3) Clean the ash of the furnace, vault, flue and air duct.
3. Drying methods and requirements: Drying generally consists of three methods (flame, hot air and steam). According to the boiler situation of our company, the flame method is more suitable.
(1) Concentrate firewood in the middle of the grate, accounting for about half of the grate area, and bake it with a small flame after lighting. At the same time, open the coal-fired front baffle to about one-fifth to make the flue gas flow slowly, keep the boiler water temperature at about 70℃, and try to make the flame fully and evenly heat the front and rear arch furnace walls. Keep it for 2-3 days, add a small amount of coal, gradually change the firewood for baking, and open the front baffle to. Heat the water in the boiler to a slight boiling point, and pay attention to the small temperature difference of each part and the uniform expansion of each part, so as to avoid the loss of sealing of the furnace wall after drying and the cracking of the furnace arch.
(2) When drying, the furnace wall and arch are not cracked and deformed to be qualified, and then the temperature is slowly increased by increasing ventilation. If the temperature rises too fast, the boiler parts will be damaged. Generally, the starting pressure needs 1-2 hours, and the water can be changed properly during the heating period to reduce the temperature difference between the upper and lower rows. At this point, check the joints (flange, water level gauge, pressure gauge, valve, etc.) for leakage. ), and
(3) Pay attention to the rising speed of temperature in the whole oven drying process. Generally, it takes 5-7 days to dry the boilers in our company after overhaul, and 7- 15 days to re-install the furnace wall or newly pour the furnace arch.
4. Precautions before oven ignition:
(1) Volatile oils and flammable materials (gasoline, solvents, etc.) are strictly prohibited. ) to light the fire.
(2) The chimney can't be ignited when there is insufficient or no pumping strength. Heat the bottom of the chimney with firewood and grass if necessary.
5. Two days before the oven is completed, caustic soda or trisodium phosphate solution can be used to burn the oven, and the dosage is 5 kg and 3 kg per cubic meter of boiler volume. The drugs used in the oven are prepared into a uniform solution with a concentration of 20%, and it is not allowed to directly add solid drugs into the oven. Open the manhole of the upper drum. Inject the prepared liquid medicine into the boiler drum at one time, then close the manhole and open the safety valve or the secondary steam valve, so that the air and steam in the boiler have a channel for external discharge.
6. Inject the treated water into the boiler through the economizer, and the water supply must be slow. The water supply time shall not be less than one hour in summer and two hours in winter, and the water temperature shall not exceed 90 degrees to prevent the temperature difference of the drum from being too large. Let the water level in the boiler rise to 2/3 of the water level gauge, close the water supply valve, and observe whether the water level drops after the water level in the boiler is stable.
7. Before the grate 1- 1.5m, spread a layer of 20-30mm cinder, put a board without nails on the cinder, and light it again with oil cotton yarn or other igniter.
8. firewood should be gradually strengthened, and the pressure in the furnace should be maintained for the first 4-6 days. If the pressure rises, the safety valve should be opened, and water should be replenished in time when the water level drops. After 4-6 days, the induced draft fan and blower can be turned on intermittently for ventilation. After the pressure gradually rises to 0.4MPa, the combustion should be stopped for one day (24 hours), so that the pressure gradually drops below 0. 1MPa and the water temperature drops to 70 degrees.
9. After the boiler is cooled, open the manhole hand hole and wash the inside of the boiler with clean water, and conduct inspection. If there is still oil stain, bake it as above (with wood fire for at least 3 hours) until there is no oil stain in the drum. When the effect of the oven and the cooking oven meets the requirements, the pressure can be increased.
Third, the booster:
When there is no problem in all aspects and all-round inspection, you can enter the booster program. Before entering the water, you must close the drain valve, open the safety valve or open the auxiliary steam valve to exhaust the air in the boiler.
1. Water enters the boiler slowly through the economizer, and the water temperature cannot be higher than 90℃. When the water level rises to the lowest level of the water level gauge, close the water supply valve and observe whether the water level drops.
2. Put firewood on the grate, open the flue gas baffle of induced draft fan, and increase natural ventilation. After ignition, start the induced draft fan intermittently and manually add coal intermittently. When the coal seam burns violently, close the ignition door, mechanically add coal for continuous fire, adjust the air volume, and keep the negative pressure in the furnace at -20-30 Pa. Pay attention to close the door before turning on the blower, so as to reduce the motor load and facilitate the start-up, and always pay attention to whether the water level is within the normal range, so as to achieve high exhaust and low compensation.
3. The temperature rise should not be too fast, otherwise it will affect the service life of the boiler. The pressure required for the initial temperature increase from the cold furnace to the air pressure must be not less than 7 hours, and then not less than 2 hours for the cold furnace and not less than 1 hour for the hot furnace except in special circumstances.
4. When the safety valve is opened and steam comes out, flush the pressure gauge and water level gauge. Method: Turn on the tap, turn off the tap, turn off the steam tap, turn on the steam tap and turn off the tap. The water level line should fluctuate slightly.
5. When the pressure rises to 0.2-0.3 MPa, check whether there is leakage at the joint of manhole and hand hole, and check whether the drain valve is tight. At the same time, use water supply equipment and drainage device, pay attention to the water level before drainage, and check the operation flexibility of the drainage valve.
6. When the pressure in the boiler rises gradually, pay attention to whether there is any special noise in various parts of the boiler. If yes, check it immediately, and stop for maintenance if necessary.
7. After boosting to the required pressure, adjust the coal seam thickness, grate speed and ventilation according to the boiler load and coal quality, and the three cannot be adjusted separately, otherwise it will lead to unbalanced combustion conditions, resulting in high energy consumption and low efficiency.
Four, when the pressure in the workshop rises to the required pressure, the boiler enters a stable operation state, and the fireman should perform the following normal operations while monitoring the pressure indication and water level display at any time:
1. Water level adjustment, try to achieve balanced and continuous water supply, and make up less frequently, but the fluctuation shall not exceed 40mm, so as to keep the water level slightly fluctuating near the normal water level line (the lowest water level line of the company's boiler is in the middle of the water level gauge). If the water levels displayed by the two water level meters are different, the reasons should be found out immediately and corrected and maintained. During normal operation, the water level must be kept above the lowest water level line.
2. The stability of steam pressure mainly depends on the combustion adjustment of operators. During normal operation, the pressure gauge must be monitored at all times, and the change of boiler pressure shall not exceed the design working pressure, indicating the contradiction between evaporation and load. When the evaporation is greater than the steam load, the air pressure will rise, and when the evaporation is less than the steam load, the air pressure will drop. Therefore, the adjustment of boiler pressure is also the adjustment of evaporation, and the amount of evaporation depends on the adjustment of combustion by the fireman.
3. Combustion regulation: It plays a very important role in the normal operation of the boiler. Combustion must be adjusted according to the change of load, and the supply of fuel must be increased or decreased accordingly. The increase or decrease of fuel must also adjust the corresponding ventilation rate, and then the speed of the grate. The grate speed mainly controls the position of the fire bed, which will make the pressure before and after unstable, and also lead to incomplete combustion and black smoke to reduce the efficiency of the boiler. The chain furnace of our company should keep thin coal seam, fast grate and small ventilation.
4. In order to achieve the goal of safe, economical and stable operation, the following work must be done:
(1) The furnace temperature is high, mainly depending on the coal quality. For example, coal with high ash content, low carbon content and low volatile matter has low calorific value, so the furnace temperature will not be high. In terms of coal quality, the flame is generally observed with eyes. The flame is orange with high calorific value, but the furnace temperature cannot exceed 1300℃.
(2) Ensuring proper carbon dioxide is also related to operation. In the process of operation, adjusting the ventilation directly affects the excess air volume. With the increase of flue gas, the volume will increase and the content of carbon dioxide will decrease accordingly.
(3) As fuel, the combustible substance in ash should be reduced as much as possible, and the residual carbon content should be less than 25%.
(4) Reduce the exhaust temperature. By adjusting and making full use of the economizer, the flue gas temperature should be controlled at 170- 180℃ under the rated evaporation.
(5) As far as the thermal efficiency of boilers is concerned, the thermal efficiency will be different if the evaporation of each boiler is different, and the evaporation is directly proportional to the thermal efficiency. The thermal efficiency of our boiler should be above 60%.
(6) The adjustment of negative pressure mainly depends on the adjustment of air volume. The amount of air must be adapted to the combustion conditions of the furnace. If the negative pressure is too small, it may spray flames, burn the oven door or endanger the safety of personnel. Excessive negative pressure will reduce the furnace temperature, increase the heat loss and reduce the thermal efficiency of the boiler. In the test of negative pressure, it is more appropriate to use a lighter or other flame to suck the flame into the furnace at the fire hole of the furnace door, and the negative pressure in the furnace will be kept at -20-30.
5. Normal combustion should be that the fire bed is flat, the flame is dense and evenly yellow, there is no cold pit, and the combustion is light gray.
6. Adjust the boiler load and combustion chamber according to the steam required by the workshop. Ensure the stability of air pressure. When the load increases, first increase the induced air volume, then increase the air supply volume, then increase the grate speed, and if necessary, increase the coal seam thickness; When the load is reduced, the grate speed should be reduced first, then the air supply volume should be reduced, and the coal seam thickness should be reduced if necessary.
7. The fuel is hot secondary bituminous coal, and the maximum lump coal is less than 40 mm.. Before the coal enters the boiler, add water and stir evenly. Iron cannot enter the boiler to avoid getting stuck in the grate.
8. Coal seam thickness and grate speed are related to coal quality and furnace load. Under the normal operation of most fuels, the thickness of coal seam should not exceed 170 mm, generally between 90-120 mm. After the adjustment of coal seam thickness, it is not advisable to move more. Only when the coal type changes or the load changes can the thickness of coal seam be changed.
9. How much water should be added to the coal? To ensure that the fire is ideal, the coal in the coal hopper will not bridge. Generally, it is most suitable to knead it into a loose ball by hand, and the water content is between 10%- 13%.
10. After the coal enters the furnace, it should catch fire within 0.3m from the coal door. Under any circumstances, it is not allowed to burn under the coal gate. If there is a fire at a distance of 0.4m or more from the coal gate, it is flameout. If you burn under the coal gate, you can add water appropriately to speed up the grate. In case of flameout, the fire hook at the oven door can be used to ignite.
1 1. Coal should be burned 0.5m before the grate tail. Coking should be carried out when coking is found, and the coke block should not exceed 300 mm If there are pits or unevenness in the hearth, it should be raked flat to ensure the hearth is flat.
12. Long-term fire extinguishing should be avoided, because long-term fire extinguishing row and side plates on both sides of the grate cannot be cooled enough, which will bring:
(1) The two side plates of the grate are bent and stuck;
(2) The grate is easily damaged due to overheating;
(3) The grate shaft is bent.
13. The reason why the grate is stuck:
(1) The tightness of nuts on both sides is quite different, and the grate deviates;
(2) The grate arches at the sprocket and gets stuck with the side sealing block;
(3) Due to iron, the grate is broken, the countersunk screw is loose, and the grate is stuck;
(4) Resistance to large area coking.
14. In general, the exhaust valve of the boiler is fully closed from beginning to end and fully opened in the middle. According to the steam consumption and load, the intermediate damper can be adjusted, but the coke must be burned out at the tail 0.5m
15. The broken coal dust in the front coal hopper can be recovered and continue to burn after being evenly mixed with coal.
16. Discharge means that the alkalinity of boiler water cannot exceed the specified range, and the discharge amount is adjusted according to the results of chemical analysis. Sewage is discharged regularly, and the effect is better when the boiler is under low load, and the header is under low load. In the case of maintaining the effect, the time should be as short as possible so as not to affect the water cycle. Pay attention to the water level when discharging sewage. It must be noted that two or more sewage pipes must be used.
17. Specific operation of blowdown: First, fully open the second blowdown valve (the one far away from the boiler), then slightly open the first one, preheat the pipeline, and then slowly open the first one. After discharging the sewage, slowly close the first one, and then close the second one. The purpose is to make the first one just a control valve to keep the second one tight. When the first one leaks, you can use the second one.
18. Inspection items after sewage discharge. After the sewage is discharged, try to feel whether the pipeline is cooled by hand.
19. In order to ensure that the water level is clear and there is no false water level, each shift must be cleaned on time for easy operation.
20. In order to ensure ventilation, the ventilation room holds two meetings regularly (each shift).
2 1. The refueling points of the front and rear rollers, gearbox and shaft sleeve must be refueled once per shift to ensure the normal lubrication parts.
22. The water treatment pressure gauge must be controlled between 0.20-0.4Mpa and 0.4 MPa to ensure pressure stability and qualified effluent.
23. In order to reduce the damage of the induced draft fan impeller, the lower seal of the dust collector must be closed. When ash is discharged, there can be a small amount of furnace ash in the temporary storage tank at the lower part of the dust collector (generally, there is no black smoke from the chimney).
24. Always monitor whether the boiler is working normally.
25. Do a good job in cleaning, succession, safety and inspection of the boiler room.
Verb (short for verb) turn off:
1. Temporary fault shutdown: first turn off the blower, slightly turn on the induced draft fan, stop the grate, and remove the coal gate to prevent the coal gate from burning out. Deal with faults quickly. If the fault cannot be solved within 1-2 hours, please stop the furnace temporarily and continue to solve the fault.
Temporary shutdown: planned shutdown, with specific steps as follows:
(1) Before stopping the boiler, according to the steam consumption, stop the coal supply furnace 20-30 minutes in advance, reduce the smoke exhaust speed to the slowest, lift the ignition door, stop the coal door after the coal enters the coal door 200-300 mm in front of the grate to prevent a large amount of cold air from entering the blower properly, and stop blowing after the coal is burned.
(2) After cooling, the water level should be lowered, so the water level should be higher than the normal level when the boiler is stopped.
(3) After the steam supply is stopped, the pressure in the boiler drops to 0, and then the main steam valve and the flue gas regulating valve are closed.
(4) After there is no fire on the grate, naturally ventilate the boiler.
(5) After the coal is burnt out, restart the high-speed grate to remove the coal ash, and stop the rotation of the grate after it cools down.
Stop the boiler completely. Generally, it will stop once every 2-3 months. Pay attention to the safety and maintenance of equipment when stopping the furnace. After stopping the boiler according to step 2, only when the boiler water is cooled to below 70 degrees can the boiler water be released, and then the safety valve is lifted to make the inside of the drum communicate with the atmosphere. If it is necessary to shorten the cooling time, cold water can be injected through the water supply pipeline and hot water can be discharged through the drain valve, but the water level shall not be lower than the normal water level. After the boiler water is discharged, open manholes and handholes, and rinse the water pollution with clean water.
Emergency shutdown: generally, measures taken to ensure personal and equipment safety after a major boiler accident, mainly to prevent the accident from expanding. The specific steps are as follows:
(1) Stop blowing first, and then stop inhaling.
(2) Immediately stop feeding coal, and pull out the residual coal before discharging, and stop air supply.
(3) Set the grate speed to the maximum, so that the coal in the grate can fall into the slag hopper as soon as possible, and water the ash.
(4) Open the air door of each air chamber, stop inducing air, and conduct natural ventilation.
(5) Continue to rotate the grate until it cools down.
If the steam in the workshop stops for a short time, stop the grate immediately, turn off the air inlet fan and pay attention to the water level. If the pressure continues to rise, stop introducing air, properly discharge sewage and decompress, and observe the water level. When there is no slag in the slag extractor, stop the slag extractor and be ready to start at any time.
Maintenance of intransitive verbs
There are two methods, dry method and wet method. Dry shutdown for more than one month, wet shutdown for less than one month.
Dry method: put pot water to remove dirt, rinse it clean, dry it in the furnace with low fire, and put quicklime in the pot without contact with metal. The weight of quicklime is calculated as 8 kilograms per cubic meter of barrel volume. Close manholes and handholes and check them every three months. If quicklime becomes powder, it must be replaced immediately. Take out the quicklime when the boiler is running.
Wet method: drain the boiler water, clean up the dirt, rinse it, fill it with water, heat the water to 100 degree, let the gas in the water out of the furnace, and close all valves. Don't use wet method in winter to avoid freezing the boiler.
Seven. maintain
1. The following points should be paid attention to during boiler operation.
(1) positive pressure combustion is not allowed in the furnace, because it is easy to burn out the gate, fire door and arc tube bracket.
(2) If it is found that the front arch brick is damaged and falls off, it should be stopped and replaced within 24 hours.
(3) In the oil cup of the sprocket shaft and cylinder in front of the grate, the bearings should be tightened once per shift, so come on.
(4) Each shift should check the lubricating oil in the head reducer of speed regulating device and the bearing box of induced draft fan. The oil level should be kept within the changing range. If it is shallow, it should be refueled in time, and the oil leakage should be eliminated in time.
(5) If the induced draft fan vibrates violently, stop the machine for inspection. In general, the internal impeller should be replaced due to wear.
(6) Do not accumulate water on the ground plane at the bottom of the boiler to prevent moisture from corroding the base.
2. The boiler shall be inspected once every 2-3 weeks.
(1) Check whether the front arch is broken.
(2) Turn the chain grate with no load, check whether there is any grate piece broken at the chain shaft in front of the furnace, and replace it if there is.
(3) Water level gauge, valve and pipeline flange are leaking and should be repaired.
3. The boiler shall be shut down once every six months for comprehensive inspection and maintenance. In addition to the above two tasks, the following tasks should be performed:
(1) Open the top cover of the economizer, remove the dust at the pipeline, remove the elbow and remove the internal dirt.
(2) Remove the scale and sludge from the drum, water wall tube and all headers, and rinse with clean water.
(3) Remove soot and coal ash from the heating surface of water wall tube and drum.
(4) Check whether there is corrosion inside and outside the boiler, such as welding seam of pressure parts and inside and outside the steel plate. If serious defects are found, they should be repaired as soon as possible. If the defect is not serious, it can be repaired at the next shutdown. If there is any doubt, but it does not affect the safety in production, it should be recorded for future reference.
(5) After passing the inspection, boiler paint can be painted on the surface to prevent corrosion.
(6) Check whether the power bearing of induced draft fan is normal and the degree of wear of impeller and shell. Users should always keep spare parts for impellers.
(7) When necessary, remove the furnace wall, shell and insulation layer for thorough inspection. If serious damage is found, it must be repaired before it can be used again. At the same time, fill in the inspection results and repairs in the boiler safety technology register.
4. Boiler insulation cover and boiler base (including grate bottom plate and lower plane of blast pipe) shall be painted at least once a year.
5. The boiler running for more than one year should do the following inspection and maintenance:
(1) The speed regulating device of induced draft fan, reducer of slag extractor and bearing box shall be disassembled and cleaned, and the lubricating oil shall be replaced. If the meshing surface of the safety clutch is polished, it should be repaired, and if the oil seal is damaged, it should be replaced.
(2) Check the wear of the friction parts of the slag extractor and repair them in time.
(3) Disassemble the grate machine, check the wear of the chain, grate plate, grate pin, rear micro flange shaft, bracket and grinding bar on the bottom plate, and replace it when it is seriously worn.
When pulling the grate, the grate must be pulled from the front to the back according to the running direction, and it is not allowed to be pulled backwards. The wire clamp cannot be removed at the wire rope buckle to avoid the lower part being stuck. When installing the rear drum, pay strict attention to the parallelism of the axis to avoid the grate running off.
6. Hydrostatic test steps:
(1) During the water pressure test, if the inlet water temperature is kept at about 20-30 degrees, low temperature will easily cause condensation on the outer wall of the boiler, which will be confused with water seepage and increase the inspection difficulty; If the temperature is too high, it is easy to cause uneven thermal expansion and cold contraction, while if the surface temperature is too high, water droplets will evaporate, making leakage difficult to find.
(2) When the water is full and the pressure rises gradually, check the leakage, and tighten the screws of flange manhole door and hand manhole cover once if necessary.
(3) During the water pressure test, the water pressure should rise and fall slowly. When the water pressure rises to the working pressure, stop boosting, check for water leakage or abnormal phenomena, and then boost it to the test pressure for 20 minutes. If the pressure does not drop, it should be reduced to the working pressure for inspection, and the pressure should remain unchanged during the inspection.
(4) If there is any leakage, it should be recorded and repaired when the pressure drops to atmospheric pressure.