长距离多泵联合运行输水系统停泵水锤防护措施

Protective measures for pump-stopping water hammer of water transfer system with long distance and cooperation of multiple pumps

运用水锤理论和特征线法,结合工程实例,对采用缓闭式蝶阀、空气阀和单向调压塔等防护措施的长距离多泵联合运行输水系统停泵水锤进行计算和分析,得到了管道沿程的水头包络线以及泵端性能参数相对值的变化曲线。计算结果表明,无防护措施下最小水锤水头较低,泵端性能参数变化较大;泵端蝶阀防护可以有效地控制泵端性能参数流量和转速变化幅度,但水头的变化出现了振荡,最小水锤水头值降低;采用空气阀+泵端蝶阀防护可以有效地增加最小水锤水头值,只在管道局部出现负压,但与泵端蝶阀防护相比性能参数变化有所增大;单向调压塔+泵端蝶阀对停泵水锤防护效果最为明显。为了减小单向调压塔数目,最终选择单向调压塔+空气阀+泵端蝶阀的组合作为最终的防护措施,与无防护措施相比,组合防护下整个管道不出现负压,泵端水头虽出现了振荡,但幅度不大,流量最大变化幅度下降0.15,转速最大变化幅度下降0.7,转矩振荡时间变短。

The water hammer theory and characteristic curves method combined with engineering example were used to analyze the pump-stopping water hammer of water transfer system with long distance and cooperation with multiple pumps which adopts such preventive measures as liquid-off butterfly valve,air valve,and one-way surge tank.The water hammer head line along the pipeline and curve for the relative values of performance parameters of the pump were obtained.The results showed that the minimum water hammer head is lower and variation of performance parameters of pump is larger without preventive measures ; the protection with the butterfly valve can effectively control the variation of performance parameters of pump flow rate and speed,but the variation of water hammer head shows oscillation and the minimum water hammer head is lower than that without preventive measures ;the protection with air valve and butterfly valve can effectively increase the minimum water hammer head,the negative pressure appears but only in the local area,and the variation of performance parameters of pump is larger compared with that of the butterfly valve protection; and the protection effect with one-way surge tank and butterfly valve is the most significant.In order to reduce the number of one-way surge tanks,combination of the one-way surge tank,air valve,and butterfly valve was selected as the final preventive measure.Compared with the pump without preventive measures,negative pressure disappeared in the whole pipe,although the water head showed oscillation with low range.The maximum variation of flow rate dropped by 0.15,the maximum variation of rotational speed dropped by 0.7,and the oscillation time of the torque became shorter.