坑口电站主机冷却系统的技术经济方案比选

Comparison and selection of technical economical schemes of main machine cooling system in a mine mouth power plant

应用国民经济评价方法,对某坑口电站水库混合供水(直流供水和再循环水冷系统)冷却方案和冷却塔二次循环冷却方案进行差额投资国民经济内部收益率比较,得出水库混合供水方案优于冷却塔二次循环冷却方案的结论。该方案的技术先进性、经济性在于:高纬度、山麓水库水温较低,末级长叶片汽轮机背压较低,机组朗肯循环效率高;可最大限度减少水资源蒸发损失,节水效益突出;解决了水库冬季融冰难题,并符合水库"温排"标准;项目规模大,社会效益贡献突出;煤矿、火电、水电、水库项目一体化集约优势相得益彰,综合开发效益显著,发电成本较低;是直流供水冷却系统在干旱地区的创新应用。

Using national economic evaluation method,the internal revenue rates under differential investment of two cooling schames of a mine mouth power plant,which are reservoir composited cooling water supply( once-through cooling water supply and recirculating water cooling system) and cooling tower secondary circulation method, were compared. The comparison conclusion is that the scheme of reservoir composited cooling water supply is superior to the cooling tower secondary circulation method. The technical advancement and the economy of the scheme are as below. The water temperature of the reservoir,whch is locates in piedmont of high latitude area,is more lower.The back pressure of the steam turbine with final stage long blade is lower. The Rankine cycle efficiency of the unit is higher. The evaporation loss of the water resource is reduced as far as possible,so the water saving effect is excellent. The difficulty of the reservoir to melt ice in winter is solved,and the discharge is meets with the standard of thermal discharge of the reservoir.The scale of the project is larger,and the social effect is favourable. The coal mine,the thermal power generation,the hydropower generation and the reservoir were developed integratedly,which formed great intensive advantages and comprehensive development effects. The generating cost of the plant is lower. The reservoir composited cooling water supply scheme is an innovative application of the once-through water supply cooling system in arid region.