How to Operate Industrial Steam Boilers

//How to Operate Industrial Steam Boilers

How to Operate Industrial Steam Boilers

I. Industrial Steam Boilers structure introduction

The new chain grate Industrial Steam Boilers is horizontal type three-pass water tube and fire tube boiler. Threaded smoke pipe is arranged in the drum, which is the third pass. The second pass is the flue gas duct under the Industrial Steam Boilers drum, and there is bare tube water cooling wall in left and right sides of the furnace. Light chain grate is used to achieve mechanical coal feeding. FD fan and ID fan are used for mechanical ventilation, and slag remover are used for mechanical slagging.

The coal will be loaded into the coal bin through the coal feeder, and then falls to the chain grate to burn. The fire goes through the burning chamber, the flue duct, the front smoke chamber, threaded smoke pipe, rear smoke chamber, economizer and dust collector, and finally goes into the chimney via the ID fan.

The softened water flows into the Industrial Steam Boilers drum through the feeding water pump, absorbing the heat from every heating surface and comes into steam, and exports to the steam manifold by the main steam valve.

II. Ignition of Industrial Steam Boilers

1. There must be a full examination (including attachments, pipes) on the coal boiler before ignition, and then water feeding. Before feeding water, make sure the blow off valve is turned off while the discharge valve is turned on, to ensure that the air in the drum could be exhausted.

2. Fill the Industrial Steam Boilers drum with processed softened water slowly, the water temperature is generally no higher than 40 oC, when the water level in the drum reach the lowest level of the water gauge, feed-water valve should be closed, check whether the water level is reduced or not until the water level is stable.

3. Before ignition, everything should be prepared as the way of coal fired boilers, the furnace of the Industrial Steam Boilers should be purged.

4. In the progress of ignition, open the fire gate, use firewood or some other materials (Attention: No nails) to make fire. When the fire is bigger, you should start feeding coal by hand, then you can open the blower, close the fire gate after the fire flamed brightly, at the same time, add coal to the coal bin and turn on the grate intermittently, observe the burning condition from the observation hole, you can stir the fire correctly. Until the front arch is hot, adjust the FD fan and ID fan, keeping the negative-pressure of the Industrial Steam Boilers furnace negative pressure of 2030Pa.

5. The temperature increases should not be too fast when ignition, to make sure that the Industrial Steam Boilers life is not affected due to the excessive heat stress. The right time for the Industrial Steam Boilers furnace to reach the normal working pressure is 3~4 hours at the first time of ignition.

6. You should pay attention to the water level after ignition. You should open the blow off valve when the water has reached the maximum water level.

7. When the steam is emitting from the blow off valve, you should shut down the blow off valve immediately, and wash the pressure gauge bending tube and water gauge. When the pressure rose to 2~3 atmospheric pressure, check whether the manhole and hand hole cover are leaking or not. If it leaks, you should tighten up the manhole and hand hole bolt.

8. When the air pressure of the Industrial Steam Boilers gradually increases, check if the Industrial Steam Boilers has special noise, if necessary, the Industrial Steam Boilers should be shutdown immediately.

III. Adjustment  the safety valves of Industrial Steam Boilers

Please adjust the opening pressure of the safety valve, when the Industrial Steam Boilers pressure has reached the authorized pressure.

1Adjustment method of the safety valve

Remove the cotter pin and the cover, loosen the hex locknut, and then adjusting screw to make the spring relaxed or tightened, to reach the exhaust pressurre of the safety valve. Then tighten the nut, and assemble other parts.

2Adjustment of the safety valve shall be from the higher opening pressure to the lower opening pressure.

3Screwing the adjusting bolt casually is prohibited after all the safety valve have been adjusted correctly.

4You should make sure that the water level within the Industrial Steam Boilers drum is slightly lower than usual, and get ready to feed water at any time after the safety valve is open.

5Do not hit on any part of the safety valve, can only use lifting handle to open the safety valve.

6Before the safety valve is adjusted correctly, the Industrial Steam Boilers is absolutely prohibited to run. The safety valve should be sealed as soon as it is adjusted, any movement is not allowed, and records must be made.

7To prevent the valve element and valve seat be stuck together, you should have manual discharge test periodically and adjust and check at least once a year.

IV. Steam supply of Industrial Steam Boilers

If the steam pressure in the Industrial Steam Boilers drum is getting close to the working pressure, the water level is supposed to be lower than the normal level, and the flame in the Industrial Steam Boilers furnace should be stable when the Industrial Steam Boilers is ready to supply steam.

Open the total steam valve slightly to let a small quantity of steam to warm the pipe, while opens the wash-out valve to spills the condensate water. The time of warming pipes is up to length and diameter of the pipe and the steam temperature, generally not less than 10 minutes. Pay attention to the expansion of pipeline and pipe bracket when warming. If there is any wrong circumstance, stop warming the pipe and eliminate failures. Open the total steam valve when the condensate water is less and less and the pipe is hot. Open the main valve slowly, while paying attention to all parts of the Industrial Steam Boilers, if there is any special sound, check the coal boiler immediately, the operator may has a shutdown if necessary. Roll back the hand wheel for half circle of the total steam valve after the total steam valve has been widely open to prevent the valve can not roll due to being heated. Test the subsidiaries, valves, instruments again, check for whether there is a situation of leakage after the coal fired boiler begin to supplying steam. In order to prevent the hanging water (steam with water), the water level should not exceed the maximum level allowed limits in any case. Meanwhile the total steam valve should not open too large, generally 1.5-2 circles. The Industrial Steam Boilers can reach the rated output under combustion conditions.

industrial steam boilers operation manual
industrial steam boilers manual

V. Industrial Steam Boilers Normal operation

Requirements for normal operation of the Industrial Steam Boilers: The water level in the drum is normal and the steam pressure is stable. Keep the boiler room clean and tidy and handover the duty when the worker is off duty. You should strengthen the supervision of the mechanical equipment and instrument, to ensure the safe and reliable operation. The firemen should summarize the operation experience periodically, and constantly improve the operation level.

1. Water quality

The water quality must meet the demands of Water quality for Industrial Boiler.

2. Water level

Pay attention to the water level changes in the drum; maintain the normal water level in the range of ± 25 mm, no more than the maximum or below the minimum safe level. Generally, there is have a slight shaking phenomenon of the water level in the water gauge, if the water level is stay still, there may be a jam in the water gauge, the water gauge should be washed immediately.

3. Water gauge

Wash the water gauge at least one shift, to keep the glass pane clean and to ensure that water level is clear and easy to distinguish. Tighten the padding when the gasket of the glass pane was found leaking. If the glass pane is not clear and the water level is hard to distinguish after washing, it should be replaced. Each coal fired boiler has two water gauges, if one of them is breakdown, repair it immediately. If both of them are breakdown, shut down the coal boiler until one of the water gauge gets right.

4. Feed water pump

A test of whether each feed water pump is working properly when job shift is requirable, if any pump is out-of-order, repair it immediately.

5. Steam pressure

Pay attention to changes of pressure, keep stable pressure inside the drum as much as possible, not exceeds the maximum allowable working pressure.

6. Pressure gauge

Pressure gauge pipe should be washed once by a shift, check weather the pressure gauge is normal, repair or change it if it is broken. In order to ensure the accuracy of pressure gauge, it should be adjusted based on the provisions of national metrology department, and then it should be sealed.

7. Safety valve

Pay attention to weather the safety valve is normal, pull the lifting handle periodically to prevent the spool and valve seat be sticked together, and to carry out the discharge test (drum steam place safety valve) and drain test (economizer safety valve). Steam pressure should be increased once every two weeks, to carry out the discharge test for the purpose of adjusting the safety valve.

8Normal operation

The normal combustion working condition in the Industrial Steam Boilers furnace should be: fire bed is flat; flame is dense and bright yellow; no cold air blast in the burner; Burning zone is tidy; Smoke from the chimney is light gray; negative pressure is between 20Pa and 30Pa; Exhaust gas temperature is about 160 ℃.

You should adjust the Industrial Steam Boilers load according to the steam consumption situation to guarantee the stability of the steam pressure. The steam-demand department should reinforce the connection with the boiler room and inform the boiler room half an hour ahead if there is any steam demand change. When the Industrial Steam Boilers load increases, first increase the ID fan air and then increase the FD fan air, seed up the grate, and increase the coal steam thickness if nessary.

When the Industrial Steam Boilers load decrease, slow down the speed of the grate firstly, reduce the blast, then reduce the wind, thinning coal steam thickness if necessary.

Use the induced-draft control to increase or decrease the air flow, keep the furnace negative pressure between 20Pa and 30Pa after the adjustment.

Cinder (0 ~ 5 mm) is improper for boiler, the coal bigger than mesh screen is appreciated, the largest coal size should not exceed 50 mm.

The fuel layer thickness and the grate speed have much to do with fuel performance and furnace fuel load. General bituminous coal may have a rapid combustion of the thin steam, the recommended coal seam thickness is 90 to 120 mm.

Speed change of the grate

a.The non-polar governor should carry out the non-polar smooth adjustment when governor transmission block is on.

b. There is a connection with the securing pin to ensure the breakage of the output shaft for overload breakdown, and stop the grate. If the safety pin fractures, find out the reason, and change a new one, but do not replace the safety pin with nails or iron wires.

The coal steam thickness should not change once be adjusted, except the situation of that the type of coal has changed or the Industrial Steam Boilers load has a dramatically fluctuation.

The shortage of the coal in the coal bin is not allowed, purging the bridging of chips (the coal squeezed in the coal bin that can not reach the grate) at any time.

The higher fuel water content is, the long ignition setup time will be. For high volatile fuel (bituminous coal), in order to prevent the coal would burn below the coal gate, the coal should be piled up and wet up. The water should be well-distributedthe water volume should ensure that the fire is ideal and avoid the bridging of chips in the coal bin. Generally the bet situation is the coal could be kneaded, the most suitable water content of the coal is between 10% and 20%.

The coal should be ignited out of reach that 0.2 meter from the gate. In any case, the coal should not be ignited below the gate, or the coal gate will be burned out. If the coal was ignited at the reach of 0.4meter from the coal gate, this situation is called “blow-off”.

If the coal burns below the coal gate, you may increase the watering quantity and speed up the grate.

Move the burning coal to the fuel bed that has just come into the furnace by the fire hook from the observation hole when “blow-off”, another choice is to input firewood, speed up the ignition or slow down the grate.

The coal steam should burnout at a distance of 0.3 meter from the end of the grate, and form dark coal clinker. There should be a certain thickness of slag blanket to prevent the grate be exposed under the flame. Pay attention to the end of the grate, if there is any red flame (including dark red not burned-out coal) piled up at the end of the grate, stir the fire immediately (push the red fire forward), to make the coal burned out completely.

Slag cleaning is necessary when coking, the coke size should not larger than 300mm, to ensure that the coal clinker can move into the slag extractor. If the coke is too big, break it into pieces and change the coal to another type. If both sides of the wall under the front arch cokes, you should conduct slag cleaning from the ignition switch.

If there is any crater on the grate or the grate is not flat, you should level the surface of the grate to make sure the grate is flat.

Long-time banking fire should be avoided, which will lead to that the grate and the plates of both two sides are not cooling enough, and that may cause these mistakes:

Grate is easy to overheat and break down

The two sides of the grate is bending for overheat, the long pin of the grate will be stuck.

The long pin of the grate bends. Keep the coal steam from the coal gate at a distance of 100mm when short-time banking fire, to prevent burning down the coal gate (short-time refers to 1~2 hours).

Attentions on that if any part has special noise of the Industrial Steam Boilers, if necessary, the coal boiler should be shutdown immediately, before it can continue to run normally.

In the event of being stuck when the coal fired steam boiler is running, it may be caused by the following reasons:

There is a big difference between the adjustment nuts of the different sides, which resulting in a serious deviation.

The side seal angle steel sticks the grate at the arch in the chain wheel shaft

Some iron objects, pieces of the common link or the fallen sunk screw sticks the grate.

Large size of coke increases the resistance.

The tightness between the grate

Generally, there should be a total clearance of about 15mm, if the clearance is too narrow, the grate will hunch-up in the head and lead to a jam, while if the clearance is too wide, that will cause too much coal dust fallen down from the clearance. Tighten the nut of the mounted grate in the cold state to prevent the grate hunching-up at the chain wheel. The tightness extent should be appropriate, not too tight. The grate may hunch-up after being heated. Loosen the four screw bolts of the low tank shell of speed control box and movable layer board, then tighten the rating nut, tension the traveling grate stoker to solve the hunch-up problem. The distance of the left and right sides must be the same when tighten or loosen the nuts to eliminate deviation.

The front gate and the tailgate of the grate register are generally closed while the gates in the middle of the grate are fully opened. Only in this situation that ignition and the fuel are nonflammable, the head gate will open appropriately.

The slag extractor can be intermittent run, the slag extractor will continuous run in the condition of that the ash fuel is burning. The water level of the slag extractor water seal should remain a high-enough altitude, to prevent the deformation of the slag extractor for high-temperature coal clinker, and prevent cold-blast air bleed into the furnace.

(21) If the iron objects or coking coal clinker sticks the slag extractor, just have a rollback for a while and then run normally by manual operation on the electric cabinet to deal with the trouble. If that does not work, just shut down the Industrial Steam Boilers to solve the problem.

(22) The engine oil cup of anteroom posterior axis of the grate should be checked once a week and be top up. Infusing the bearings with engine oil every shift.

(23)Recycle the coal dust in the ash bucket, it may burn again after string.

How to operate industrial steam boiler
How to operate industrial steam boilers

VI. Industrial Steam Boilers Blowdown

Despite the common water has been soften, the water still contains some minerals, the steam enter the boiler after heating treatment, the minerals concentrated to a certain extent remains in the pot, and settle down in the pot, the quantity of the precipitate is up to the estimation and running time of the Industrial Steam Boilers. In order to prevent the burnout of the Industrial Steam Boilers for scale, slag, etc., the quality of boiler water must be guaranteed. The alkalinity of the Industrial Steam Boilers water should be less than 24mol / L. As long as the alkalinity exceed the above range, blowdown may be necessary.

General users may discharge on a regular basis according to specific circumstances when the test conditions are not perfect, not less than 1-2 times every shift.

Attention items of blowoff:

1. Blowoff of two or more coal boilers at the same time are not allowed when the two or more coal fired boilers use the same blowdown pipe. If the repairing is under way of one Industrial Steam Boilers, the connection between the Industrial Steam Boilers and the blowoff pipe must be cut down before blowoff.

2. The Industrial Steam Boilers should be adjusted to a low load and a high water level when blowoff. Watch out for the water level in the drum. It is advise to decrease the water level to the scope of 25mm~50mm when blowoff.

3. Each Industrial Steam Boilers is equipped with two discharge valve in tandem. The second blowoff valve (the further one from the boiler) should be fully open, then open the first one (close to the Industrial Steam Boilers) slightly to preheat the blowdown pipe. Open the first blowoff valve slowly after preheating. When the blowoff is done, close the first blowoff valve slowly, and then close the second one. The purpose of the operation is to control the progress of blowoff by the first blowoff valve and keep the leak-proof of the second one. If the first valve leaks, the second one can still be use. If there is impact sound in the blowdown pipe when blowoff, turn down the first valve until the sound disappears. Blowoff should not be carried out continuously for a long time, to ensure that will not to affect the water cycle.

If a valve is tandem with a quick open blowdown valve, firstly open the valve and then open the blowdown valve slightly, fully open the blowdown valve rapidly after warming-up. Lose the blowdown valve slowly after blowoff, and then the valve. The function of the valve is to sealing while the blowdown valve is to control the whole progress of blowoff.

4. After completion of the blowoff and the blowdown valve is closed, the leak-proof of the blowoff, the check method is as follows: a few minutes after closing the blowdown valve, put your hands on the pipe of the second blowoff valve to test whether it is cool, and there is a leak of the blowdown valve.

5. Continuous blowdown: continuous blowdown is to drain the boiler water 100mm~200mm below the estimating surface in the drum which has the biggest salt concentration, and drain the suspended solids or oil on the surface of the boiler water. The purpose is to prevent the carryover and to improve the steam quality.

The continuous blowdown quantity is based on the test result. The continuous blowdown should be carried out when the water salinity and alkalinity exceed 20% of the quota. The principle is to economize to avoid running short.

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By |2018-09-28T06:19:51+00:00March 30th, 2018|Technical Support|Comments Off on How to Operate Industrial Steam Boilers

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