July 4, 2001 occurred in a power plant due to condensate pump repair trip caused by a unit and a feed pump damage accident. At that time, No. 2 machine running, due to lack of output found condensate pump, load belt can not afford, so contact maintenance. Maintenance staff to do billing B condensate pump inlet filter. About half an hour later, the maintenance staff will B condensate pump inlet filter open. At this moment, the crew found the unit vacuum dropped sharply, the current of A condensation pump fluctuated violently, the deaerator water level dropped and the condenser water level went up. The operator immediately activated the standby jet pump to maintain the vacuum and reduce the load. After about 2min the vacuum dropped to -80.99kPa, but the low vacuum protection did not move. At this moment, the operator realized that it may be caused by the overhaul of the condensate pump, and immediately went to the manual valve of the inlet of the condensing pump B and terminated the overhaul work. However, the effect was not obvious and the deaerator water level continued to drop. After about 7 minutes, A to the pump current began to fluctuate, A pump cavitation. After 4min, stop A feed pump, start B feed pump, feed pump B is still slightly cavitation. At this point the operator aware of the key, immediately go off A, B condensate pump air door, but it is too late, condensate pump air can not be discharged for a moment, the water can not get rid of. After about 4 minutes, the condenser is full of water and the vacuum is reduced from -83.9 kPa to -77.9 kPa, with low vacuum protection. Local inspection and found that B to the pump balance pipe was broken, serious water leaks, so stop B to the pump 1 cause of the accident 1.1 maintenance staff and operating personnel are ignored closed condensate pump air doors 1, 2, the ticket issuer did not Work tickets fill in this security measures, the operators did not add, so that when the maintenance staff to open B inlet pump condensate pump, the atmosphere and the condenser and A condensate pump body connected, leading to a sharp decline in vacuum, A condensate pump Into the air can not hit the water. This is the root cause. 2 low vacuum protection is not in accordance with the provisions of the action (vacuum as low as -83kPa protection should be action), resulting in the accident to expand, so that B damage to the pump. 1.3 The operator to determine the accident is not timely, to deal with the accident is not decisive, resulting in damage to the B pump. After careful analysis to determine the damage to the pump B is due to the processing time is too long lead to deaerator water level drops, so that the feed pump cavitation, resulting in feed pump balancing drum and bushing killed, and the impeller and the seal ring mild touch mill. 2 Prevention of Accidents 2.1 Revalidation of Work Ticket Issuer and Work Permit Holder This is an accident caused by an operator unfamiliar with the system. However, as a work ticket issuer and work ticket permitter at the same time overlooked a clear safety measure, exposing the problem of the work is not strong sense of responsibility. Work ticket issuer received the inspection task to fill the ticket, but to fill in the safety measures more casual, consider not comprehensive; work ticket permitter to take the ticket only in accordance with the security measures to complete, but does not consider whether the measures are comprehensive, over-confident And rely on maintenance personnel. Therefore, on the one hand, candidates for job ticket issuers and job ticket licensors are required to have a high level of business skills and a good understanding of the site system; on the other hand, they are required to have a strong sense of responsibility for work. 2.2 to strengthen technical training and improve the operational level of operational staff In this accident, as the operating staff, first, there is no system to reliably isolate and pay and overhaul; second is to determine the lack of ability to accident, when the condensation pump current swing and Did not make timely, accurate and accurate judgment when playing no water. Third, deal with the accident is not decisive, when the deaerator water level dropped to dangerous levels did not promptly shut down the gate, resulting in damage to the feed pump. This shows that the operating staff poor level of business. Therefore, it is necessary to do a good job in the following two aspects: First, to organize a back-examination of systematic drawings to enhance understanding of on-site systems; and second, to carry out regular anti-accident exercises so as to enhance their ability to judge and handle accidents. 2.3 Equipment maintenance operation of the unit to strengthen the operation of the unit in operation to repair the equipment, the inspection program should be reported to the relevant leadership and professional and technical personnel, and approved by the leadership. At the same time stressed that equipment should be reliably withdrawn from the system, technicians should be confirmed to the scene and guidance, and then start construction overhaul. Obviously, in the condensate pump overhaul process, if there are professional and technical personnel in the presence of supervision and guidance, the accident can be avoided. 2.4 Strengthen the inspection of protection devices to ensure the accuracy of their actions. On the one hand, they must carry out action tests on protection on the one hand, and on the other hand, strengthen their usual maintenance and inspection work.
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