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兩臺不同性能的渣漿泵并聯工作

圖4-5為兩臺不同性能泵并聯工作時的性能曲線。圖中曲線I、I為兩臺不同性能泵的性能曲線，曲線I+I為并聯后的性能曲線，畫法同上。III為裝置揚程性能曲線，與并聯后的性能曲線I + I的交點M, M點就是并聯工作時的工作點，此時流量為Qm，揚程為Hm。
    確定并聯時單臺泵的運行工況，可由M點作橫坐標的平行線交于A、B兩點，即為每臺泵并聯工作時的單臺泵工作點，流量為Qa、Qb揚程為H，、Hh。并聯工作的特點是:揚程彼此相等，即H =H =H。，總流量為每臺聚輸送流量之和，即Qm=Qa+Qb。

并聯前每臺泵的單獨工作點為C、D兩點，流最為0c、Q。.揚程為H、H。由圖4-5看出：

這說明兩臺不同性能泵并聯式總流量Qm等于并聯后各臺泵流量之和，即QM=QA+Qb，但總流量小于并聯前各臺泵單獨工作的流量之和，其減少的程度隨臺數的增加和設置揚程特性曲線越陡直，則輸出的總流量就減少的越多。

由圖4-5可知，當兩臺不同性能的泵并聯時，揚程小的泵輸出流量很少。甚至輸送不出去，所以并聯效果不好，若并聯工作點在C點以左，即總流址0.小于0時應該停用揚程小的臺泵。 不同性能泵的并聯 工作較復雜，故實際中很少采用。
四、泵并聯工作時注意事項
    (1)泵并聯工作時最好是泵的揚程相同或相差較小，以避免揚程小的那臺泵發揮作用很小或不發揮作用，應盡量采用兩臺同性能的泵并聯工作。
    (2)泵并聯工作時，泵的進出口管路基本上要對稱相同，以避免管路阻力大的那臺泵作用減小。
    (3)選擇泵的流量Q =效率點工作。
    (4)泵的配用功率要注意，如果單臺泵運行時流量為0。來選擇配用功率，以防原動機超功率。
    (5)為達到并聯后增加較多流量的目的，泵的性能曲線應當陡直一些較好。
    (6)為達到并聯后增加較多流量的目的，裝置揚程特性曲線越平坦越好，也就是應增加出口管路直徑，減小阻力系數以適應并聯后能增大流量的需要。渣漿泵廠家

Two slurry pumps with different performance work in parallel

Figure 4-5 shows the performance curve of two pumps with different performance in parallel. Curve I and I in the figure are the performance curves of two pumps with different performance, curve I + I is the performance curve after parallel connection, the drawing method is the same as above. III is the head performance curve of the device, M is the intersection point of the performance curve I + I after parallel connection, M is the working point during parallel operation, at this time, the flow is QM, and the head is HM.

To determine the operation condition of a single pump in parallel, the parallel line with m point as the abscissa can intersect with a and B points, that is, the single pump working point in parallel operation of each pump, with flow of QA and QB and head of H and H. The characteristic of parallel operation is that the lift is equal to each other, i.e. H = H = H. , the total flow is the sum of each aggregate transportation flow, i.e. QM = QA + QB.

Before parallel connection, the independent working point of each pump is C and D, and the flow is 0C and Q. . the lift is h, H. As shown in Figure 4-5:

This shows that the total flow QM of two parallel pumps with different performance is equal to the sum of the flow of each pump after parallel connection, that is, QM = QA + QB, but the total flow is less than the sum of the flow of each pump before parallel connection, and the degree of reduction is more with the increase of the number of pumps and the steeper the set head characteristic curve, the more the total output flow is reduced.

It can be seen from figure 4-5 that when two pumps with different performance are connected in parallel, the output flow of the pump with small head is small. If the parallel operation point is to the left of point C, i.e. the total flow address is 0. Less than 0, the pumps with small head should be stopped The parallel operation of pumps with different performance is complex, so it is rarely used in practice.

IV. precautions for parallel operation of pump

(1) when the pumps are in parallel operation, it is better to have the same or smaller difference in lift, so as to avoid that the pump with small lift has little or no effect. Two pumps with the same performance should be used as much as possible.

(2) when the pumps work in parallel, the inlet and outlet pipes of the pumps should be basically symmetrical and the same, so as to avoid the reduction of the function of the pump with large pipeline resistance.

(3) select pump flow Q = efficiency point to work.

(4) pay attention to the matching power of the pump, if the flow is 0 when a single pump is running. To select the matching power to prevent the prime mover from over power.

(5) in order to increase more flow after parallel connection, the performance curve of the pump should be steeper and straighter.

(6) in order to increase more flow after parallel connection, the flatter the head characteristic curve of the device is, the better. That is to say, the diameter of outlet pipeline should be increased and the resistance coefficient should be reduced to meet the need of increasing flow after parallel connection. Slurry pump manufacturer