centrifugal pump

Title: centrifugal pump

Author: Bustanul Arifin

Article:
Basically, the centrifugal machine is built around an impeller,
which is in series of radial vanes of various shapes and
curvatures, spinning in a circular casing. Fluid enters at the
"eye" or axis of rotation and discharges more or less radially
into a peripheral chamber at a higher pressure corresponding to
the sum of the centrifugal force of rotation and the kinetic
energy given to the fluid by the vanes. The centrifugal pump is
the type most widely used in the chemical industry for
transferring liquids of all types raw materials, materials in
manufacture, and finished products as well as for general
services of water supply, boiler feed, condenser circulation,
condensate return, etc. These pumps are available through a vast
range of sizes, in capacities from 0.5 m3/h to 2 � 104 m3/h (2
gal/min to 105 gal/min), and for discharge heads (pressures)
from a few meters to approximately 48 MPa (7000 lbf/in2). The
size and type best suited to a particular application can be
determined only by an engineering study of the problem. The
primary advantages of a centrifugal pump are simplicity, low
first cost, uniform (nonpulsating) flow, small floor space, low
maintenance expense, quiet operation, and adaptability for use
with a motor or a turbine drive. A centrifugal pump, in its
simplest form, consists of an impeller rotating within a casing.
The impeller consists of a number of blades, either open or
shrouded, mounted on a shaft that projects outside the casing.
Its axis of rotation may be either horizontal or vertical, to
suit the work to be done. Closed-type, or shrouded, impellers
are generally the most efficient. Open- or semiopen-type
impellers are used for viscous liquids or for liquids containing
solid materials and on many small pumps for general service.
Impellers may be of the single-suction or the double-suction
type--single if the liquid enters from one side, double if it
enters from both sides. Casings. There are three general types
of casings, but each consists of a chamber in which the impeller
rotates, provided with inlet and exit for the liquid being
pumped. The simplest form is the circular casing, consisting of
an annular chamber around the impeller; no attempt is made to
overcome the losses that will arise from eddies and shock when
the liquid leaving the impeller at relatively high velocities
enters this chamber. Such casings are seldom used. Volute
casings take the form of a spiral increasing uniformly in
cross-sectional area as the outlet is approached. The volute
efficiently converts the velocity energy imparted to the liquid
by the impeller into pressure energy. A third type of casing is
used in diffuser-type or turbine pumps. In this type, guide
vanes or diffusers are interposed between the impeller discharge
and the casing chamber. Losses are kept to a minimum in a
well-designed pump of this type, and improved efficiency is
obtained over a wider range of capacities. This construction is
often used in multistage high-head pumps.

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About the author:
I'm a process engineer consultant and have experience in
building a refinery plant as piping engineer. This article was
wrote base on my experience and text book. To study other kind
of pump, you can visit :

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