Rare failure phenomenon and treatment method of gas boiler

11/02/2021


As a large-scale boiler equipment, gas-fired boilers will inevitably have some failures if they are not used correctly in daily operation. For example, insufficient air volume, burnout of electrical appliances, failure to turn on, etc., these are common and easy to deal with, but you are at a loss for rare failures such as explosions and secondary combustion. This is a problem that requires a professional manufacturer to solve it. It is not recommended to handle it privately. . Next, I will explain the processing method in detail for you.

Gas Boiler

1. Accidents specific to gas boilers


The accidents of gas boilers are also diverse. In addition to the accidents of coal-fired steam or hot water boilers, their unique accidents may also occur. Such accidents usually include furnace and flue explosion accidents, secondary combustion accidents, and boiler flameouts. Accidents, boiler fire accidents, etc.


(1) Furnace and flue explosion accident


Explosion of furnace and flue is a common accident in gas boilers. This kind of accident may occur during ignition or operation, especially during ignition or maintenance. In severe cases, the furnace wall collapses, bricks fly horizontally, the furnace roof and flue are opened, and flames and high-temperature flue gas are ejected outwards, which can easily cause casualties.


1. The phenomenon of furnace and flue explosion


(1) The pressure in the furnace (negative pressure becomes positive pressure) rises sharply.


(2) Fireworks are emitted from explosion-proof doors, furnace doors, fire holes, inspection holes, etc.


(3) Make a dull or loud noise.


2. Causes of furnace and flue explosion


(1) Before the boiler is ignited, the residual combustible gas in the furnace is not removed, there is no ignition program control device, or the operating procedures are not implemented, and it is caused by blind ignition.


(2) The boiler suddenly turned off during operation and failed to interrupt the fuel supply in time.


(3) When the fuel supply pump fails and the boiler gas supply is interrupted, the boiler main intake valve is not closed tightly. When the fuel supply pump returns to normal, a large amount of gas enters the furnace.


(4) When the circuit is powered off and the blower stops, the power switch is not immediately opened to cut off the gas source. When the power is normal, a large amount of gas enters the furnace.


3. Treatment of furnace and flue explosion


(1) The furnace should be shut down immediately, and the power and gas supply should be cut off at the same time to prevent the accident from expanding.


(2) Adjust the boiler water level to normal.


(3) Inspect the boiler where the furnace and flue explosion occurred.


(4) Furnace staff must strictly follow the operating procedures. Whether it is the first ignition before the boiler is started, or the re-ignition after the boiler is turned off during operation, it must be carried out according to the ignition operation procedure.


(2) Secondary combustion accident


During the operation of the boiler, the combustibles (soot, carbon black) deposited in the flue at the tail of the boiler catch fire again, which is called secondary combustion, or reburning in the flue at the tail of the boiler. In severe cases, it will burn down the tail flue, air preheater, induced draft fan and even the economizer.


1. The phenomenon of secondary combustion


(1) The exhaust gas temperature rises sharply, the chimney emits heavy smoke, and even fire smoke appears.


(2) The negative pressure in the furnace changes drastically, and positive pressure appears.


(3) In severe cases, the flue shell is dark red.


(4) When there is an air preheater, the hot air temperature rises sharply and the air pressure is unstable.


(5) Sometimes the rear explosion-proof door will act.


2. Causes of secondary combustion


(1) The atomization of the burner is poor, and the oil and gas are not completely burned and brought into the tail of the boiler.


(2) Improper combustion adjustment, insufficient air distribution or unreasonable air distribution.


(3) The furnace temperature is low during the process of starting and stopping the furnace, and the fuel is not burned in the furnace.


(4) When the boiler is shut down or the boiler is extinguished, the air gun valve is not closed tightly.


(5) The negative pressure in the combustion chamber is too large, so that the gas is brought into the tail of the boiler before it can burn out.


(6) A certain amount of soot or carbon black has been accumulated for long-term non-stop cleaning of the tail flue.


(7) Air leakage through flue or air preheater.


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