Thermal power plant accident case analysis

Datang a thermal power plant equipment management department prepared no. 1 boiler C coal mill internal maintenance plan, after approval to implement.

Zhang Yanqiu, the person in charge of C mill maintenance working group, and the point inspector entered C mill for inspection, and found that C mill centering bracket was welded. They decided to deal with the welding opening in the hot primary air duct and the sealing gland packing fault of the baffle shaft and the hot primary air dynamic adjustment in operation.

Li Deyu, the monitor, as the general person in charge of the maintenance work site of C coal mill, allocated the maintenance work tasks in the powder making class, and sent Wang Hongliang and Tan Zhe to participate in the repair welding work of C coal mill entrance heat air channel.

In the afternoon, Li Deyu held a class meeting and arranged the work in the afternoon: The technician of the pulverized class contacted the operation personnel of the power generation management Department and arranged Li Jun to debug the baffle plate of C coal mill entrance heating for one time. The repairman of the powder making class cleans the waste thermal insulation cotton above the primary air duct and adjusts the baffle plate with the adjustment of the primary air duct; Wang Zijun, the repairman of the powder making class, is the guardian of the limited space operation. Li Deyu on the heat primary air duct welding site acceptance.

Li Jun arrived at C coal mill maintenance site, at this time, 6.9 meters platform construction scaffolding has been set up, Li Deyu, Wang Hongliang, Tan Zhe are entering the coal mill hot air channel for operation, Wang Zijun in the hot air channel monitoring.

Li Jun opened the control cabinet door at the local control cabinet with a screwdriver in the 6.9-meter platform to switch the "far control/near control" switch to the "near control" position, and pressed the solenoid valve to start the switch. There was no reaction after the first press, and still no reaction after the second press.

Li Jun shouted to the repairman on the heat primary air duct at the railing of 6.9 meters platform, asking whether the regulating baffle moved? The repairman kicked the adjusting baffle link crank with his foot and waved to show that it did not move.

Li Jun also opened the manual valve of the door air source of the C coal mill inlet heating primary air dynamic insert plate, which has a warning sign of "No operation with human work". At this time, the hot air dynamic plug door is opened, 309℃ hot air is sprayed into the C coal mill entrance heat primary air duct with a pressure of 6kPa, Li Deyu, Wang Hongliang, Tan Zhe are involved in the C coal mill entrance support bottom.

The rescue workers entered no. 1 boiler C coal mill entrance to heat the primary air duct, rescue the trapped people. But they were all confirmed dead.

The immediate cause

Maintenance process, repairman Li Jun serious violations of the operation. In does not have equipment under the condition of the related conditions, check the device name identification, to open air solenoid valve plug door and there is "no operation someone work" placard air valve manually, the original coal mill inlet hot atmosphere in a closed C moving door open, the temperature is 309 ℃, pressure is 6 kpa coal mill inlet air injection C heat within a duct, Cause the accident to happen.