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渣浆泵件磨损对泵特性曲线的影响

渣浆泵件磨损对泵特性曲线的影响

作者:admin    来源:未知    发布时间:2019-10-03 12:35    浏览量:
渣浆泵件磨损对泵特性曲线的影响
一、叶轮入口边磨损对扬程的影响
    所有易损零件可以分为两大类:第一类包括其磨损影响泵特性曲线的零件,如叶轮、叶轮入口侧密封件(密封环和调节环,护板);第二类其磨损不能响泵特性曲线的零件,如压水室、吸入管、叶轮后盖板侧护板。第一类零件不是所有表面磨损都影响泵的特性曲线。例如,甚至在叶轮盖板内表面磨损最很大时,泵特性曲线也不变化。
在运行初期,在水力磨损性液流作用下,流道表面局部粗糙度磨平,泵扬程和效率由于泵内水力损失降低面有所提高。但是,这种提高只是暂时的,因为组成叶轮入口测密封间隙零件表面开始磨损(运行是相当快),导致溢流增大,即导致泵扬程下降。
下面研究泵随着叶片入口边磨损其扬程特性曲线如何变化。
叶片逐渐缩短,特别是从后盖板侧缩短,冲角变化,叶片绕流相对速度增大。这时,与甭功率有关的理论扬程不变,而泵扬程下降,这表明叶轮入口水力损失增加。根据詹德曼实验研究结果,得到确定叶片入口边磨损所产生叶轮入口附加水力损失关系式现在确定具有下列参数泵叶轮内水力损失可能的增量:Q=300m3/h,n=600r/min,叶轮入口直径D1=500mm,叶片入口宽度b1=300mm,叶片入口边水平布置。
    由于磨损,叶片长度平均减少100mm,这就是说,当p=30°时,半径R增加50mm,即叶片入口边圆周速度增大,因此,对叶片绕流相对速度增大。
叶片磨损后叶轮入口处液流圆周速度
叶轮入口处液流径向速度
叶片入口边磨损后,叶片入口中间流束的相对速度为
叶片入口边磨损产生的附加水力损失
    如果泵扬程为48m,那么叶片人口边磨损后扬程等于48-3.6=44.4(m),扬程大约降低7%。
    在叶片入口边磨损后,泵的吸入性能恶化。随着磨损量增大,叶片入口边位置平均半径增大,这就导致叶轮入口液流轴面速度下降,而导致圆周速度u1增大,特别是在磨损量最大的地方。
汽蚀余量人是参数(an)tan(p:/2)的函数。在液流圆周速度和径向速度相对于叶片磨损后流入叶片中间流束起初点的情况下,汽蚀余量仍然是这个参数的函数。渣浆泵厂家

Effect of Slurry Pump Parts Wear on Pump Characteristic Curve
First, the influence of impeller inlet side wear on lift head.
All vulnerable parts can be divided into two categories: the first kind includes parts whose wear affects the pump characteristic curve, such as impeller, impeller inlet side seal (seal ring and adjusting ring, guard plate); second kinds of parts whose wear can not pump the characteristic curve, such as water pressure chamber, suction pipe, impeller side cover plate side guard plate. The first kind of parts does not affect the characteristic curve of the pump because of all surface wear. For example, even when the inner surface of the impeller cover is most worn out, the pump characteristic curve does not change.
In the initial stage of operation, under the action of hydraulic abrasive fluid flow, the local roughness of the runner surface is smoothed, and the head and efficiency of the pump are improved due to the hydraulic loss reduction surface in the pump. However, this improvement is only temporary, because the surface of the parts formed by the impeller entry seals is worn (running very fast), causing the overflow to increase, that is, the pump head will drop.
The following is how the pump's lift characteristic curve changes along with the blade inlet side wear.
The blade is gradually shortened, especially from the side of the back cover plate, and the relative velocity of flow around the blade increases with the change of the angle of attack. At this time, the theoretical lift related to power is not changed, and the pump head decreases, which indicates that the hydraulic loss of impeller inlet increases. According to the results of Jandman experiment, the additional hydraulic loss relation of impeller entry at the inlet of the blade is determined. The possible increment of hydraulic loss in the impeller is determined as follows: Q=300m3/h, n=600r/min, impeller inlet diameter D1=500mm, blade inlet width b1=300mm, and blade inlet side arrangement.
Due to wear, the blade length decreases by an average of 100mm. That is to say, when p=30 degrees, the radius R increases 50mm, that is, the circumferential velocity of the blade inlet side increases, so the relative velocity of the blade flow increases.
The circumferential velocity of impeller flow at the inlet of the impeller after wear.
Radial velocity of impeller flow at inlet of impeller
The relative velocity of the flow in the middle of the blade inlet is
Additional hydraulic loss caused by wear of inlet blades
If the pump head is 48m, the head of the blade is 48-3.6=44.4 (m) after the blade edge wear, and the head is reduced by about 7%.
After wearing at the inlet of the blade, the suction performance of the pump deteriorates. With the increase of wear volume, the average radius of the entrance edge of the blade increases, which results in the decrease of the axial velocity of the impeller inlet and the increase of the circumferential velocity U1, especially in the area where the wear is greatest.
Cavitation margin is a function of parameter (an) Tan (p:/2). When the circumferential velocity and radial velocity of liquid flow are relative to the initial point of flow beam flowing into the blade after wearing, the cavitation margin is still a function of this parameter. Slurry Pump Manufacturer
 

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