Page 304 - Centrifugal Pumps 2E

272 Centrifugal Pumps: Design and Application

hydraulic turbine when gain over synchronous speed is achieved and to
drive the hydraulic turbine at low flow capacities where input HP Is re-
quired.
The output and input HP is determined by use of a wattmeter with effi-
ciency curves for the induction machine, A torque meter may also be
used to measure the power. A venturi meter or an orifice is used to mea-
sure the flow capacity. Dead weight testers and Bourdon-type gauges are
used to measure the head. The RPM change from synchronous speed is
counted by use of a strobotac and stop watch.
The turbine test may be performed at a reasonable reduced speed to
facilitate testing. The performance at normal speed is then determined by
applying the "affinity laws". The availability of a drive pump with suffi-
cient head and flow capacity is a determining factor for the test speed.
Cavitation tests are needed for hydraulic turbine performance character-
istics. This is best determined by reducing the turbine outlet pressure and
observing any resulting changes in the total dynamic head of the turbine,
the power, the capacity, or efficiency. Measurements of noise, pulsation,
and vibration accompanying the operation of the turbine during the cavl-
tation test should be recorded.

Applications

Any continuous process where high pressure liquid or partially gas-
saturated media is let down to a lower pressure across a reducing device
is a potential application for an HPRT. Such potentials are:

• In pipeline service on the downside of high mountain ranges to keep the
pipeline full and avoid excessive pressures.
• In bleeding products from a high-pressure point in the pipeline to stor-
age.
• In geopressured-geothermal zones where high-temperature water is at
a very high pressure. The formation pressure may exceed 10,000 psig,
while pressure at the surface may approximate 2,000 to 6,00 psig de-
pending on flow rates.

The early HPRT applications were basically in the noncorrosive and
nonerosive service. Modern plants use HPTR's nowadays in mildly se-
vere services such as:

• In hydrocracking operations, where boosting pressure of charge stocks
to the 1,500-2,000 psi operating pressures used in modern hydrocrack-
ing processes requires large quantities of energy. Effluent from the re-