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1、探讨泵运行工况的调节方法泵运行工况的调节方法常用的两种基本方法是：一是改变装置扬程性能曲线，可用节流调节法二是改变泵本身的性能曲线，可用变速调节、切割叶轮外径调节、汽蚀调节可转动叶片调节、增减叶轮数目及泵的串联并联工作等方法一、节流调节节流调节就是在管路中装设节流件，如阀门。孔板等通过改变阀门的开度大小来改变管路阻力从而改变了装置扬程性能曲线也可以加一个小孔的孔板，它用于固定流量的调节常只用在出口管路上，因为在进口管路上易使泵发生汽蚀节流调节方法简单、易行、可靠并且可以再泵运行中动态下随时改变故广泛应用于中小型泵中的调节二、变速调节变速调节是改变泵性能曲线来改变泵的工作点的其优点是没有附加损失
2、，所以很是经济变速调节因受泵的强度限制，一般只用于降速调节不得任意提高转速，以免损坏泵，在降速调节时一般泵的效率会有所下降，并随降速幅度增大而下降增大所以转速降低一般不得低于 50%，否则会使泵的效率降低太多三、切割叶轮外径：切割叶轮外径就是将叶轮外径进行车削当叶轮外径改变后，与原叶轮在几何形状上并不相似，但当改变量不大时可近似地认为叶片切割前后出口角不变，流动状态近似相似叶轮外径切割后，泵的效率有所下降尤其是切割量较多时，效率下降较大，并且计算误差也较大所以泵叶轮外径切割也有一定的限制切割叶轮外径调节简单、可靠、经济其缺点是叶轮切割后，不能再恢复泵的形状并且不能在动态下改变四、汽蚀调节汽蚀调
3、节仅用于凝结水泵中的调节，调节时把泵的出口调节阀全开，当汽机负荷变化时也就是凝汽器的凝气量相应变化时，供水泵进水位的变化来调节泵的流量达到汽轮机的排气量的变化与水泵输水量自动平衡的目的五、可动叶片调节当改变叶片安放角时，泵的性能将随之改变所以将叶片制作成可转动可改变叶片安装角就可改变泵的性能从而达到调节的目的六、减少叶轮数目调节在多级泵中，减少叶轮数目来降低泵的扬程从而达到调节的目的，所以只能用在多级泵中Adjustment Method of Pump Operation ConditionTwo common methods of pump operation conditions adj
4、ustment method are:One is to change the equipment head performance curve,we can use the throttling adjustment; the other is to change the pumps performance curve,we can use the methods of variable speed adjustment,cutting impeller outer diameter,Cavitation control,rotating blade adjustment,increasin
5、g or decreasing impellers number and pumps series and parallel connection.1.Throttling AdjustmentThrottling adjustment,that install throttling element in the pipeline,like valve,orifice plate.Change pipe resistant by changing the opening size of valve,which is changing the equipment head performance
6、 curve.We can also add a small orifice plate to fix the flow adjustment.Because the cavitation is much more likely to happen on inlet pipeline,so it is often used on the outlet pipeline.The throttling control method is simple,easy and reliability,and during the pump operation it can change at any ti
7、me.So it is widely used for the small and medium pumps adjustment.2.Variable Speed AdjustmentThe variable speed adjustment can change pumps working point by changing pumps performance curve.The advantage is no additional loss,so it is very economic.The variable speed adjustment is limited by pump,ge
8、nerally it is used for speed reduction adjustment.We cant improve the speed freely,for fear of damaging pump.During the speed reduction adjustment,generally the pumps efficiency will reduce,and it will reduce as the decreasing speed increase.So the speed reduction cant lower than 50%,or the pumps ef
9、ficiency will reduce too much.3.Cutting Impeller Outer DiameterCutting impeller outer diameter,which is carrying out the turning on impeller outer diameter.When the impeller outer diameter has changed,its geometrical is not same as the prime impeller.But when its change is small,we can think its out
10、let angle is the same,and the flow condition is similar.After cutting,the pump efficiency will reduce,especially when the cut is great,the efficiency reduce sharply,and the error is large.So the cutting impeller outer diameter has some limitations.Cutting impeller outer diameter is simple,easy,and e
11、conomic,and its disadvantage is that after cutting,the pumps shape cant be recovered and it cant be changed under dynamic condition.4.Cavitation ControlThe cavitation control is just used to adjust condensate pump,during the adjustment,Open the pump outlet control valve.When the machines load change
12、s,that is the condensers condensate changes.The change of water pumps inlet location can be used to adjust pumps capacity,and to balance the change of turbines displacement and the pumps water transfer quantity.5.Rotatable Vane AdjustmentWhen changing vane angle,the pumps performance will change.So
13、making the vanes into rotatable and changeable vane angle to change pumps performance,then achieve the adjustment goal.6.Decrease the number of ImpellerThe multi-stage pump can be decreased impellers number to reduce pump head,then achieve the adjustment goal.So it can only be used on multi-stage pump.
