Chemical Engineering : CENTRIFUGAL PUMP

PUMP


Pumps play a vital role for liquid conveyance. A large number of pumps differing widely principal and mechanical construction.


SELECTION OF PUMBS

The following consideration should be taken-

1. The amount of liquid that must be pumped

2. The head height to which the liquid would be pumped

3. The properties of the fluid

4. Types of flow

5. Pumping rate of capacity is litre/min.


TYPES OF PUMPS

1) Centrifugal pump
2) Reciprocating pump
3) Gear pump/ Rotary pump


CENTRIFUGAL PUMP

The centrifugal pump is the type most widely used in chemical industry for transfering liquid of all types.


centrifugal pamp
Centrifugal pump


Centrifugal pumps are the most widely used for liquid pumping because they are capable of transfering large volume without any dependence on valves or fine clearance & can be run against a closed valve without developing very high pressure.

The device can be simple so that lining of the volute & the covering of the impeller with any required material is possible. For example rubber or plastic or glass lined pumps are readily available. Further more centrifugal pumps are most versatile in that they handle wide range of slurries or solid suspension in addition to liquid with high viscosity.

The principal of operation is to draw fluid into the centre of the casing % sweep it towards the periphery by blade spinning at high speed.


CAPACITY

Pumps are available through a vast range of size in capacities from 2 or 3 gal/min 100,000   gal/min.


HEADS

The centrifugal pumps can discharge the fluid over the few feet up to several thousands.

Single stage centrifugal pumps are available in capacities up to and over 50,000 gal/min, for heads (pressure) up to 1600 feet

OPERATION

In the centrifugal pump the liquid is fed to the centre at a rotary impeller & it is thrown outwards by centrifugal action. As a result at high speed of rotation of impeller, the liquid acquires a large kinetic energy & a pressure difference is produced by the conversion of K.E into pressure energy.

centrifugal pamp
Centrifugal pump


ADVANTAGES

1. Construction is simple
2. No value is involved
3. Maintenance cost is low
4. It can handle slurries
5. Need no grease


DISADVANTAGES

1) Can't be operated at very high head
2) There is a limitation of delivery pressure
3) There is a friction between the easing and blades.

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