Page 189 - Centrifugal Pumps Design and Application

164 Centrifugal Pumps: Design and Application

Figure 10-32. Performance of two half-capacity full head pumps installed in par-
allel plotted against system head curve.

shared equally, and there is less chance of a pump operating at less than
minimum continuous stable flow. Figure 10-32 shows our system curve
and two half-capacity full head pumps installed in parallel. In this partic-
ular system, parallel configuration is a poor choice. When only one
pump is running, it is necessary to throttle to stay within operating range.
Parallel configuration should be considered in systems where a sub-
stantial portion of the head is static. When pump configuration is not
clear cut, it is wise to plot each station curve along with pump curves and
carefully analyze parallel versus series operation.

Waterflood Pumps

Many types of pumps are used to extend the life of declining oil fields
by injecting displacing fluids at pressures ranging from 2,OCX) psi to
8,000 psi. In waterflooding applications (secondary recovery), centrifu-
gals are preferred when injection capacities exceed 10,000 BPD. Typical