某火电厂水资源利用及污染防治改造方案和经济分析

Transformation scheme and economic analysis of water resource utilization and pollution control for a thermal power plant

火电厂取排水普遍存在不能严格满足机组建设环境影响评价批复和排污许可证等环保要求的问题。针对华北某典型2×600 MW燃煤开式循环冷却型电厂取排水存在的问题,提出了针对性改造方案,并进行了经济性分析。生产水源由水库水更换为中水,新建原水预处理系统,提高循环水浓缩倍率,建设循环水排污水脱盐系统;湿除渣系统基于水量平衡和热量平衡,捞渣机设计为内置式换热实现零溢流;化学车间废水分类收集,完善生活污水收集和处理系统,处理后按质回用;脱硫废水经预处理后,采用旁路烟气干燥工艺实现固化。电厂水资源利用及污染防治改造对废水分质收集、分类处理、梯级利用,实现了中水回用和全厂废水零排放,满足环保要求,项目总投资9 980万元,增加年运行费用1 707.68万元,扣除每年节省取水费1 423万元,单位电价成本增加0.49元/(MW·h)。

There is a common problem that the drainage of thermal power plants can not strictly meet the environmental protection requirements such as environmental impact assessment approval and emission permits for unit construction.In view of the problems existing in the drainage of a typical 2×600 MW coal-fired open circulating cooling power plant in North China,a targeted transformation scheme was proposed and the economic analysis was carried out.The production water source was replaced by reclaimed water,the raw water pretreatment system was newly built,the concentration ratio of circulating water was improved,and the desalination system of circulating water sewage was constructed.Based on water balance and heat balance,a heat exchanger was installed inside the hull of the slag machine of the wet slag removal system,and the water supply was optimized to achieve no discharge of slag water.The chemical workshop wastewater was collected separately,domestic sewage collection and treatment system was improved and reused according to quality after treatment.The pretreated desulfurization wastewater was solidified by bypass flue gas drying process.The water resources utilization and pollution prevention and control of power plants were classified collection,classification treatment and cascade utilization,so as to realize the reuse of reclaimed water and the zero discharge of wastewater in the whole plant to meet the requirements of environmental.The total investment of the project was 99.8 million yuan,the annual operating cost was increased by 1.776 8 million yuan,and the unit electricity cost was increased by 0.49 yuan/(MW·h) after deducting the annual saving of water collection fee of 14.23 million yuan.