超大型离心泵站过渡过程计算及水锤防护

中短距离的超大型离心泵并联泵站在我国灌溉系统中并不多见,但随着规模化农业的发展以及跨流域调水的需求,泵站大型化是一个发展趋势,针对国外一特大型灌溉泵站(8×8000 kW)在各种特征工况下的启停过渡过程进行了计算和分析,根据计算结果提出了防护措施及运行建议:对于最大高差的组合水位,如阀门拒动将导致主泵倒转超过1.3倍额定转速,需采用两阶段关阀进行防护;经计算,正常或事故停泵工况,采用30 s/0.25~90 s/0°两阶段关阀程序可满足所有工况防护要求。但对于并联系统,运行期间需要注意单泵启停对同组其他泵的影响,启停水泵必须由其后的逆止阀实施相应保护,如阀门拒动,则需全停对应泵组。

Water Hammer Protection in Super Large Centrifugal Pumping Stations

Super-large pumping station with parallel centrifugal pumps in irrigation of our country is rare yet.Nevertheless,with the development of the scale of agriculture and the demand of the inter-basin water transfer,large-scale pumping station,is a developing trend.A super-large irrigation pumping station(8×8000 kW)is introduced in this paper.Startup-shutdown transition process in the cases of slowly closing disc valve is presented according to the calculation results.For the combined water level with the maximum height difference,for example,disc valve rejection will cause the reverse speed to more than 1.3 rated speed,two-stage closing procedure of check valve shall be adopted for protection.According to the calculation,in normal or accident pump shutdown conditions,the two-stage closing procedure of 30 s/0.25~90 s/0 can ensure the system's safety.However,for the parallel pumping system,the disturb of the startup or shutdown to the other pumps in same group should be paid attention to.The pumps should be protected by the check valve.If the check valve of tripping pump cannot be closed,the others corresponding pumping group shall be completely shut down immediately.This study provides an important guidance for the safe operation of high head and large flow centrifugal pumping stations.