如图1- 46所示,(H-Q)1和(H-Q)ll分别为两台不同性能泵的性能曲线,串联后总性能曲线的画法与图1- 45相同，在流量相同的各点把扬程叠加起来，得到(H-Q)1+u性能曲线。它与管路特性h- Q曲线的交点M为串联后的工作点。过M点作垂线,分别与(H一Q)1和(H- Q)π曲线交于A,和A2点，即两泵串联后的工作点，其参数仍然符与单泵在管路中工作时相比,流量增加,而扬程降低了,所以串联后的总扬程H1.小于两泵单独工作时的扬程之和，减小的程度与管路特性徒峭度有关。
若管路特性曲线h - Q与串联后性能曲线(H-Q)1。n交于C点,这时的流量和扬在与第一台泵单独工作时相同，第二台泵不起作用，只消耗功率。若管路特性移到图1-46中(h- Q)c的位置时,这时流量和扬程都小于只有第一台渣浆泵单独工作的流量和扬程。其原因是第二台泵相当于装置的过流元件，增加了阻力,减少了输送流量。为此，C 点可以作为极限状态，工作点只有在C点左侧时串联工作才是合理的。
What is the effect of two slurry pumps with different performance in series
As shown in Fig. 1-46, (H-Q) 1 and (H-Q) ll are the performance curves of two different performance pumps respectively. The drawing method of the total performance curve after series connection is the same as that in Fig. 1-45, and the head is superposed at each point with the same flow rate to obtain (H-Q) 1 + U performance curve. The intersection point m between it and H-Q curve is the working point after series connection. When the two pumps are connected in series, their parameters are still consistent with that of the single pump working in the pipeline, the flow rate increases, and the head decreases. Therefore, the total head H1 after the connection is smaller than the sum of the two pumps working alone, and the degree of reduction is related to the kurtosis of the pipeline characteristics.
If the pipeline characteristic curve H-Q and the performance curve after series connection (H-Q) 1. N intersect at point C, then the flow and lift are the same when the first pump works alone, the second pump does not work, only consumes power. If the pipeline characteristics are moved to the position (H-Q) C in Fig. 1-46, the flow and head are smaller than the flow and head of the first slurry pump working alone. The reason is that the second pump is equivalent to the flow element of the device, which increases the resistance and reduces the delivery flow. Therefore, point C can be regarded as the limit state, and it is reasonable to work in series only when the working point is on the left side of point C.