两台不同性能的渣浆泵并联工作

图4-5为两台不同性能泵并联工作时的性能曲线。图中曲线I、I为两台不同性能泵的性能曲线，曲线I+I为并联后的性能曲线，画法同上。III为装置扬程性能曲线，与并联后的性能曲线I + I的交点M, M点就是并联工作时的工作点，此时流量为Qm，扬程为Hm。
    确定并联时单台泵的运行工况，可由M点作横坐标的平行线交于A、B两点，即为每台泵并联工作时的单台泵工作点，流量为Qa、Qb扬程为H，、Hh。并联工作的特点是:扬程彼此相等，即H =H =H。，总流量为每台聚输送流量之和，即Qm=Qa+Qb。

并联前每台泵的单独工作点为C、D两点，流最为0c、Q。.扬程为H、H。由图4-5看出：

这说明两台不同性能泵并联式总流量Qm等于并联后各台泵流量之和，即QM=QA+Qb，但总流量小于并联前各台泵单独工作的流量之和，其减少的程度随台数的增加和设置扬程特性曲线越陡直，则输出的总流量就减少的越多。

由图4-5可知，当两台不同性能的泵并联时，扬程小的泵输出流量很少。甚至输送不出去，所以并联效果不好，若并联工作点在C点以左，即总流址0.小于0时应该停用扬程小的台泵。 不同性能泵的并联 工作较复杂，故实际中很少采用。
四、泵并联工作时注意事项
    (1)泵并联工作时最好是泵的扬程相同或相差较小，以避免扬程小的那台泵发挥作用很小或不发挥作用，应尽量采用两台同性能的泵并联工作。
    (2)泵并联工作时，泵的进出口管路基本上要对称相同，以避免管路阻力大的那台泵作用减小。
    (3)选择泵的流量Q =效率点工作。
    (4)泵的配用功率要注意，如果单台泵运行时流量为0。来选择配用功率，以防原动机超功率。
    (5)为达到并联后增加较多流量的目的，泵的性能曲线应当陡直一些较好。
    (6)为达到并联后增加较多流量的目的，装置扬程特性曲线越平坦越好，也就是应增加出口管路直径，减小阻力系数以适应并联后能增大流量的需要。渣浆泵厂家

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