Cause of ignition deflagration accident and safety measures

The fundamental reason for the deflagration in the hearth is that the combustible mixture accumulates in the limited space of the hearth or in the passage of the boiler, the smoke duct, and the fan that transports flue gas to the chimney. Furnace deflagration is caused by unreasonable operation, unreasonable equipment or control system design, or failure of equipment and control systems. The origin of the deflagration accident is the accumulation of combustibles. It is now concluded that the following situations are prone to deflagration:

1 ) Auxiliary fuel leaks into the unburned furnace and ignites the accumulated combustibles through sparks or other sources of ignition.

2 ) Repeated failure to ignite the auxiliary fuel without proper purging, resulting in the accumulation of explosive mixtures.

3 ) The furnace turns off instantly. After recovery and delay, the accumulated combustibles are reignited.

4 ) Insufficient amount of fluidization in the hearth, there is a dead zone where flammable substances can easily accumulate, resulting in incomplete combustion and accumulation of combustibles.

Ignition deflagration accident safety precautions

Furnace deflagration is generally caused by unreasonable operation, unreasonable design of equipment or control systems, or failure of equipment and control systems. The key to preventing ignition deflagration accidents of circulating fluidized bed boilers is to formulate reasonable safety start-up procedures, perfect trial procedures for ignition devices, and improve thermal logic protection. The following preventive measures are formulated according to the different conditions and causes of ignition deflagration accidents. To deal with emergencies in a timely manner.

1 , perfect thermal control logic protection

1 ) Unlike CFB boilers and pulverized coal fired boilers, the purge zone before the ignition of the boiler includes the furnace hearth and the ignition air duct. According to the original logic of the HQP company, it must be ensured that the air volume entering the furnace is greater than 30 % of the total design air volume. Scan the time to ensure that the purge is performed and the replacement gas is reached to prevent ignition detonation.

2 ) Perfect oil gun and coal feeding conditions

The oil gun on the bed does not have an ignition device and is heated to the ignition temperature by the bed material and hot air. Therefore, the bed oil advances the oil speed and the valve opens. When the quick-break valve fails or is overhauled, the state of the air duct burner cannot be correctly reflected, and the oil speed cutoff valve is further improved. The atomization valve opens and detects the flame, ensuring reliable operation of the oil gun on the bed. Due to the lack of rationality in design of the system due to the lack of rationality in the design of the bed burner and the oil gun on the bed, the fuel and atomized steam purges cannot be put into operation for a long time. When the oil guns are stopped, the pressure fluctuations are large, and the less the oil gun is, the greater the fluctuation is. To achieve the protection value, from the commissioning of the unit to production, pressure protection has not been put into high protection. Therefore, after a successful ignition of the fuel gun, it should be suspended for 10-30 minutes before being put into operation again. If it is unsuccessful for two consecutive times, it will be notified to the inspection and repair unit and must not be resumed.

3 ) Strengthen the oil gun purge control

The original logic gun is a manual purge, and purge can still be performed after the OFT action. Manual purging does not guarantee that the lance can be purged after each use, so be sure to manually purge the lance and record every time the lance is shut down.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.