火力发电机组凝汽器抽真空系统节能改造优选方案研究

Optimization solution of condenser vacuum system energy-saving reconstruction for thermal power generating units

凝汽器抽真空系统节能潜力较大,其实际运行差异大,目前尚缺乏一种有效的优选改造方案。本文以水环-罗茨真空泵组、水环真空泵工作液深度冷却、蒸汽喷射泵3种典型抽真空系统改造方案为研究对象,详细测量和分析了凝汽器严密性、循环水进水温度、机组负荷率对3种凝汽器抽真空系统改造方案节能收益的影响,并与原有水环真空泵进行了比较。结果表明:当凝汽器严密性达到优秀时,仅水环-罗茨真空泵组改造方案产生节能收益;当原有水环真空泵抽真空系统出现抽吸量不足时,水环真空泵工作液深度冷却、蒸汽喷射泵抽真空系统节能改造方案可产生节能收益,且随机组负荷率降低、凝汽器严密性变差而升高。在此基础上,给出一种根据凝汽器抽真空系统实际运行状态对3种节能改造方案进行优选的方法,为凝汽器抽真空系统节能改造可行性研究及实施提供重要参考。

The vacuum extraction system of condenser has remarkable energy saving potential. It is still lack of an effective method to optimize the various technical solutions, because of the wide difference on the condenser air extraction system’s actual operating condition. By taking the transformation scheme of three typical vacuum pumping system as the research object, such as water ring-roots vacuum pump group, water-ring vacuum pump working fluid deep-cooling and steam jet vacuum pumping system, this paper detects and investigates the effects of condenser tightness, circulating water inlet temperature and unit load rate on energy saving benefits of the retrofitting schemes. Moreover, the results were compared with the original water ring vacuum pump. It shows that, when the condenser tightness is excellent, only the water ring-roots vacuum pump group retrofitting scheme can produce energy saving benefits. When the suction of the original water ring vacuum pump is insufficient, the schemes of water ring-roots vacuum pump group, water-ring vacuum pump working fluid deep-cooling and steam jet vacuum pumping system can produce energy saving benefits, and the benefits increase when the unit load rate decreased and the condenser tightness got worse. On this basis, this paper gives out a method for optimizing the three energy-saving modification schemes according to the actual operation state of the condenser vacuum pumping system, which provides an important reference for feasibility study and implementation of energy-saving retrofitting for condenser vacuum pumping system.