Power Recovery Turbines
A hydraulic turbine can be considered a “waste heat” recovery unit. It actually recovers energy when letting down high-pressure streams to lower pressures.
As an example, in a Hydrocracker there are process pressures that must be dropped from 2500 PSIG to 120 PSIG, and to 40 PSIG. This let-down energy can furnish about one half the power required to pump the incoming feed up to the process pressures.
Figure 3200-16 illustrates the principle. A full size motor and a full size spare should be installed. As power recovery takes over, the load on the electric driver is reduced.