How to deal with abnormal boiler pressure?

EPCB Boiler provides you with industrial boiler maintenance experience - how to deal with the problem of industrial boiler abnormal pressure.

Boiler looks like simple industrial equipment, but the incorrect application may cause large-scale chemical accidents. The boiler pressure gauge is one of the important indicators to reflect the boiler state and prevent boiler accidents. If the pressure gauge is abnormal, how to deal with the problem in time?

Firstly, we should analyze the causes of pressure gauge anomalies in combination with other situations. Generally speaking, there are several reasons as following for pressure gauge anomalies (the specific situation still needs to be analyzed by professionals, here only share the common reasons):

1.      Boiler overpressure

Boiler overpressure:

·         If the pressure rises sharply and exceeding the permissible working pressure, the pressure gauge pointer exceeds the permissible working “red line”, but the pressure is still rising after the safety valve operates.

·         It sends out an overpressure alarm signal and overpressure interlock protection device works.

·         Steam temperature increases and steam flow capacity decreases.

Boiler overpressure treatment:

·         Reduce burning quickly and manually open the safety valve or drain valve.

·         Increase water feeding, and strengthen the sewage discharge in the lower drum (at this time should pay attention to maintaining the normal water level of the boiler) to reduce the temperature of the boiler water, thereby to reduce the pressure of the boiler drum.

·         If the safety valve does not work or the pressure gauge is damaged, the boiler should be shut down urgently, and the pressure gauge and the safety valve should be repaired before boosting operation.

·         When the boiler overpressure and endangers the safe operation, we should take measures to reduce the pressure, but prohibit to drop its pressure too fast.

1.      Boiler tube explosion

Boiler tube explosion phenomenon

·         When the tube burst can hear the spray sound of steam and water, and there is a loud explosion noise.

·         The negative pressure changes to positive pressure of furnace combustion, and a lot of smoke and steam leakage from the furnace door and holes of the furnace wall.

·         The water feeding is abnormally greater than the steam flow rate.

·         Although the water supply is increased, the water level is often hard to maintain and the steam pressure is reduced.

·         The exhaust gas temperature is reduced and the smoke color is white.

·         The furnace temperature is lowered or even extinguishing.

·         The I.D fan load is increased, and the current increase too.

·         There is water flow out from the bottom of the boiler, and ash content increases.

Boiler bursting treatment:

·         If the tube burst and leakage are not serious and can keep water level, and the accident does not expand, the load can be reduced for a short time to maintain operation, and stop it after the standby boiler start-up.

·         When the tube bursts and can not maintain the water level, it should be shut down the boiler urgently, but the I.D Fan can not stop, the boiler should continue to be supplied water to reduce the furnace wall temperature so that the accident will not expand.

·         If the boiler tube bursts because of water shortage and overheating of the tube wall, the boiler should be shut down urgently, and water supply to the boiler should be strictly prohibited. At this time, the residual fire in the furnace should be removed as soon as possible to reduce the furnace temperature, then to reduce the degree of overheating of the boiler.

·         If there are several boilers to supply steam by paralleling, the main steam pipe of the accident boiler should be cut off from the steam main pipe.

·         The superheater tube blasting.

Superheater tube explosion accident:

·         Near the superheater has steam or jet noise or the roar of blasting.

·         The stem flow is abnormally descending, and the flow rate is smaller than water feeding abnormally.

·         The negative pressure of furnace decreases or becomes positive pressure. When it is serious, steam and smoke are emitted from the furnace door and the fire hole.

·         The temperature of flue gas after the superheater is reduced abnormally or the temperature difference of the flue gas before and after the superheater increases.

·         When the damage is serious, the boiler steam pressure drops.

·         The exhaust gas temperature dropped significantly, and the smoke emitted from the chimney became gray or white.

·         The I.D Fan load increases, and current increases too.

Treatment of superheater tube explosion accident:

·         If the superheater tube is slightly broken, the load can be reduced appropriately and the operation can be maintained in a short time. At this time, the leakage situation should be closely monitored and the standby boiler should be started up quickly. If deterioration occurs during monitoring, the boiler should be stopped as soon as possible.

·         The superheater tube must be protected urgently when the bursting is serious.

1.      Boiler water hammer.

Boiler water hammer phenomenon:

·         There is a certain rhythm of impact sound at the boiler and pipeline, and sometimes the sound is huge, accompanied by strong vibration of water supply or steam pipeline.

·         The pressure gauge pointer swings back and forth, and consistency with the frequency of the vibration.

·         When the water hammer problem is serious, it may cause some connecting parts, such as flange, weld cracking, valves, etc are damaged.

Treatment of water hammer in the furnace:

·         If the check valve fails, the combustion should be reduced to reduce the load and pressure, close the feed water cut-off valve to stop water supply, and quickly repaired the feedwater check valve. At the same time, the water level should be observed to prevent water shortage.

·         For the steam heating device on the lower drum, the steam valve should be closed quickly.

·         Keep the boiler runs at the middle water level, and feed water evenly. If the water hammer continues, the boiler should be stopped for overhaul.

·         Boiler overhaul should strengthen the repair of water supply pipes, water distribution pipes, and flume.

Treatment of steam pipe water hammer:

·         Reduce the supply of steam and shut off the main steam valve when necessary.

·         Open the trap valve on the superheater header and steam pipeline for drainage.

·         If the drum water level is too high, it should be properly discharged and maintain a normal water level.

·         Ensure the quality of water supply and boiler water to avoid the occurrence of steam-water priming.

·         After eliminating the water hammer, check the condition of pipes, pipe racks, flanges, and other places, if there is no problem, the boiler will supply steam once more after heated pipes.

Treatment of economizer water hammer:

·         Open the drain valve on the outlet box of the economizer and discharge the air.

·         Inspect the check valve on the inlet of the economizer if it damaged should be timely overhauled or replaced.

·         Continuous water supply to the boiler, strictly control the outlet temperature of the economizer, generally should be below the saturation temperature of 40 C. If it is found that the temperature is too high and vaporization may occur, the recirculation pipe should be opened, or the bypass flue should be opened, or the return pipe valve should be opened to send the water from the economizer back to the water tank.

EPCB Boiler provides you with industrial boiler maintenance experience - how to deal with the problem of industrial boiler abnormal pressure.

There is no trivial matter in safety. It is an important means to prevent safety accidents to carry out patrol tasks on time and complete hidden danger investigation in time.