Pump Type Follows:

Wednesday, August 13, 2008

Propeller and Turbine Pumps

Axial-Flow Pumps
These pumps are essentially very-high-capacity low-head units. Normally they are design for flows in excess of 450 m/h3 (2000 gal/min) against heads of 15 m (50 ft) or loss. They are use to great advantage in closed loop circulation systems in which the pump casing becomes merely an elbow in the line. A common installation is for calandria circulation.

Turbine Pumps
The terms ‘Turbine Pump’ is applied to unit with mixed flow (part axial and par centrifugal) impellers. Such unit are available in capacities from 20 m3/h (100 gal/min) upward for heads up to about 30 m (100 h) per stage. Turbine pumps are usually vertical.

A common form of turbine pump has the pump elements mounted of the bottom of a column that serve as the discharge pipe. Such units are immersed in the liquid to be pumped and are commonly used for well condenser circulating water, large volume drainage, etc. Another form of the pump has a shell surrounding the pumping element which is connected to the inlet pipe. In the form, pumping is used on condensate service in power plant and for process work in oil refineries and elsewhere.

Regenerative Pumps
Also referred to turbine pumps because of the shape of the impeller, regenerative pumps employ a combination of mechanical impulse and centrifugal forced to produce head of several hundred meters (feet) at low volumes, usually less than 20 m3/h (100 gal/min). The impeller, which rotate at high speed with small clearances, has many short radial passages milled on each side at the periphery, passing alternatively from the impeller to the casing and receiving successive impulses at it does so.

These pumps are particularly useful when low volume of low viscosity liquids must be handled at higher pressure than are normally available with centrifugal pumps. Close clearances limit their use to clean liquids. For very high heads, multistage units are available.