1 Operation before the accident Unit 3 before the accident Load 200 M W. Phase II (including units 3 and 4) The compressed air system cooling water is supplied by industrial water of Unit 3. Industrial waterworks tube pressure is 323 kPa, A and C industrial pump currents are 177, 174A, turbine oil oil cooler inlet oil temperature is 55 °C, and outlet oil temperature is 40 °C. 2 accidents passed At 20:27 on March 20, 1998, the No. 3 machine light plate issued an "industrial water pressure low" alarm. The industrial jellyfish pressure is 270 kPa and fluctuates. The industrial pump current is 134 A, and the B industrial pump is connected. The main duty officer sent someone to the scene for inspection. The inspectors found that the industrial water expansion tank overflows, and the industrial water pipeline has no leaks, the industrial water pump inlet and outlet doors are open, the industrial water pump is not faulty, and then the air is discharged to the industrial jellyfish pipe, the industrial water pump body and the closed cooler. A large amount of gas is ejected from each of the air discharge pipes. As the gas is not cleaned, the inspectors are inspected along the industrial water pipeline. At 20:35, the pressure of the industrial jellyfish tube continued to drop, and the steam turbine also tripped after the start. At 2100 hours, the industrial pump current drops below 60 A, the main pipe pressure drops to 70 kPa, the load drops to 90 MW, the turbine oil cooler inlet oil temperature is 73 °C (the cooler has been cut off), the outlet oil temperature 73 ° C, 2, 4, 6 watt metal temperature up to 100 ° C. As the temperature of the turbine lubricating oil and the temperature of each watt metal continue to rise, the central control personnel are forced to stop manually. 2°C; The metal temperature of the metal is 101.4 °C; the metal temperature of the 4th watt is 103. 4 ° C; At the same time, the inspectors checked to the air compressor room (outside the factory building) and found that the A air compressor had tripped. After that, the cooler was severely bursting, the buffer was overheated, and the rear cooler returned to the water to observe the mirror blasting. Until then, the air compressor attendant rushed to the duty site. 3 analysis of the cause of the accident (1) A air compressor after the cooler squibs, causing a large amount of compressed air to enter the industrial water system is the direct cause of this accident. (2) A large amount of compressed air enters the industrial water system, so that the inlet of the industrial water pump does not hit the air. The pressure of the main tube is drastically reduced. Each air release duct is not sufficient to drain the gas, causing the industrial water expansion tank to overflow. A vacuum pump, A, B steam pump, B condensate pump and backup equipment are tripped due to insufficient cooling water pressure and flow or high bearing temperature. The turbine oil cooler is also unable to cool the return oil because the cooling water flow rate is too low, causing the outlet oil temperature and the temperature of each watt metal to be too high, and the centralized control personnel are forced to manually stop. (3) The personnel on duty of the air compressor failed to inspect the equipment as scheduled. The air compressor buffer tank has over-temperature of compressed air, and the cooling water pressure is low. The air compressor is not found in time. The air compressor cooling water is not detected in time and reported to the main control room. It is lost. The opportunity to recover the accident. (4) The maintenance personnel did not remove the original oil stored in the cooler. After the air compressor was disassembled by the A air compressor, it was found that there was oil in the aftercooler. In the past, the industrial water system was oiled (the No. 4 coal mill lubricating oil cooler had had internal leakage), and the maintenance personnel paid insufficient attention to the oil accident. The cooler related to the industrial water system was not cleaned. When the chiller and cooling water of the A air compressor are almost interrupted, the high-temperature compressed air causes the oil to burn, causing the aftercooler and the buffer tank to burn to different degrees, and the aftercooler cooling water is returned to the water. The sight glass burns, causing a large amount of outside air to be drawn into the industrial water system. (5) There is no safety door on the water side of the aftercooler. Since the pressure difference between the two media in the aftercooler is large (compressed air pressure is 0.65 M Pa, the cooling water pressure is 0.15 M Pa), once the cooler bursts, the high-pressure compressed air will inevitably enter a large amount of low-pressure cooling. water system. Then, the cooling water outlet pipe of the aftercooler is at the inlet of the industrial water pump, so that a large amount of compressed air enters the industrial water pump, so that the industrial water pump does not hit the water. (6) The operational personnel's accident handling ability is not strong, and the system is not familiar enough. The accident phenomenon is more prominent. For example, when the industrial water system is ventilated, a large amount of gas is ejected and cannot be discharged, the industrial water expansion tank overflows, the industrial pump current is reduced, etc., and the operators fail to quickly do these phenomena. Make the right analysis and judgment. 4 preventive measures (1) When purchasing equipment, the quality of the equipment must be strictly checked. (2) Strengthen the labor discipline education of the duty personnel. The duty officer must arrive on time, check regularly, and be aware of the equipment's operating conditions and operating parameters. (3) Use the simulation machine to strengthen the training of the anti-accident capability of the operating personnel and improve the technical level of the operating personnel. Through the study of the system, improve the familiarity of the operating personnel to the various systems on site. (4) When a system such as industrial water fails, the duty personnel of all system-related equipment should contact each other to cooperate and troubleshoot. (5) In industrial water systems, there are many coolers. Leakage from each chiller can affect the operation of the entire industrial water system. The leakage accident of the oil cooler should be paid more attention to by the relevant personnel. In the event of a leakage accident, the relevant cooler must be cleaned and decontaminated. (6) For the cooler with large difference in pressure between the two media, a safety pressure relief device should be installed on the low pressure side to prevent the high pressure medium from expanding into the low pressure medium to expand the accident. (7) The low-pressure medium of all coolers should be periodically tested to monitor its quality and identify problems in a timely manner. Brodifacoum is a highly lethal 4-hydroxycoumarin vitamin K antagonist anticoagulant poison. In recent years, it has become one of the world's most widely used pesticides. It is typically used as a rodenticide, but is also used to control larger pests such as possum. 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Unit 3 of Qinhuangdao Thermal Power Plant is a domestically introduced 300 MW unit. On March 20, 1998, the unit was forced to stop operation due to the expansion of the industrial water system into the compressed air caused by the explosion of the second stage A air compressor. In order to prevent the occurrence of similar accidents, the causes of the accident were analyzed and corresponding preventive measures were taken.