Research On Optimization Of Cold-end System For Large-scale Power Plant

Cold-end system is an important auxiliary system. Its working performance directly affects operational economy and safe reliability. So, to do research of cold-end system, improve the operational performance, make sure unit in the best condenser vacuum, and realize the optimization of cold-end system operation, is an important mean for power station to reduce production cost, improve the thermal efficiency.In this paper, based on condenser variable condition theory, the calculation model of relationship between the circulating water inlet temperature, water circulation, the thermal load and the condenser performance was established. The performance impact factors of vacuum pump were analyzed and the actual ability of vacuum pump was determined. On this basis, cold-end system optimization model was established, and effective solutions for cold-end system energy saving optimization were put forward. Aiming at the problem of vacuum pump output shortage under summer condition, the mathematic model of relationship between vacuum pump output shortage and condenser vacuum was established in the paper. Two plans to improve the vacuum pump performance were presented:using air conditioning water instead of circulating water to cool the working water; installing cooling tank on suction pipe to condense the steam of the extracting vapor mixture. The vacuum system of dual-pressure condenser was analyzed, and pointed out that high pressure crowd out low pressure extraction when parallel connection mode. One connection mode that parallel and separate could be arbitrarily switch was proposed. High load, using parallel connection mode; low load, using separate suction operation. Based on the determination method of condenser optimal vacuum and cold-end optimization theory, circulating water system of dual-pressure condenser was optimized. Aiming at less economical of dual-pressure condenser under winter condition, two plans were proposed:switch to single pressure condenser operation by changing the circulating water line and bypass water circulation of low pressure condenser to improve the thermal efficiency.