水电站压力管道排水时间计算方法

Calculation method of drainage time of penstock for hydropower station

考虑管径、管道倾角、管道首末高程等的影响,建立压力管道排水计算数学模型,得到排水时间与排水阀开度之间存在反比关系.以压力管道允许水位消落速度和排水阀允许流速作为限制条件,选择合适的排水阀开度,最终确定排水时间.以某引水式水电站为例进行计算分析,获得符合各方面要求的排水步骤.分析发现,压力管道上平段主要受排水阀允许流速的限制,排水速度较快;竖井段主要受水位消落速度的限制,排水耗时较长;下平段水头小,排除少量水体也需要较长时间.

A mathematical drainage model is proposed,considering the influences of pipe diameter,inclination angle,head elevation and end elevation.Results show that there exists an inverse relationship between drainage time and drainage valve opening.Taking allowable velocity of drainage valve and the allowable water falling speed of penstock as constraints,the appropriate drainage valve opening is selected,and then to determine the drainage time ultimately.The method is demonstrated by a case study of an actual hydropower station.Finally,an optimized drainage procedure is obtained.The results show that the drainage time of upper horizontal part of penstock is mainly restricted by allowable velocity of drainage valve;the vertical shaft part is mainly restricted by allowable water falling speed of penstock.Because of low water head,it takes a long time to drain small amount of water in the lower horizontal section.