Page 293 - Centrifugal Pumps Design and Application

Hydraulic Power Recovery Turbines 261

Figure 14-10. HPRT construct Jon using singJe-volute-type case, turbine runner,
and guide vanes.

Turbine Design with Fixed Guide Vanes

Most pump manufacturers offer, in addition, different lines of turbo-
machines designed specifically to be applied as HPRT's. They are basi-
cally developed to cover a range of performance generally not available
with a reverse-running pump. One of these HPRT's is shown in Figure
14-9,
This HPRT features an axial-split single-volute-type scroll case, a sin-
gle-stage double-eye Francis-type runner, and a removable guide vane
component (Figure 14-10), that controls the inlet flow to the runner.
This type of HPRT has a fixed performance characteristic. However,
the design can accommodate seasonal or "plant turn-down" flow-capac-
ity conditions by changing to a different guide vane assembly or by using
an adjustable guide vane assembly for optimum performance. The run-
ners used in this type of HPRT are quite different from the conventional
pump impeller in that it has a greater number of vanes and generally
larger vane angles.