CENTRIFUGAL PUMPS

SUBMITTED TO-DR. H.C. THAKUR

Submitted By-Satyajeet Pal Shubham Singh Shubhendu Subodh Contact No.- 09717146360 (SUBODH)

DEFINITION

Centrifugal Pumps are a sub-class of dynamic work absorbing turbo machinery. Designed base on centrifugal forceIt is used by the conversion of rotational kinetic energy to the hydrodynamic energy of fluid flow.

HISTORY

The first mechine catagrised a centrifugal pump was a mud lifting mechine.

which appeared as earlier 1475 by Italian Renaissance Engineer Francesco Di Giorgo Martini.

Scientist Denis papin and British Inventor John Appoid in 1851 developed a modern centrifugal pump.

Types of Centrifugal Pumps

Based on number of impeller/s in the pump:Single stage - pump has one impeller only; for low head serviceTwo-stage - pump has two impellers in series; for medium head serviceMulti-stage - pump has three or more impellers in series; for high head service

Based on impeller suction:Single suction - pump with single suction impeller (impeller has suction cavity on one side only); simple design but impeller is subjected to higher axial thrust imbalance due to flow coming in on one side of impeller only.

Double suction - pump with double suction impeller (impeller has suction cavities on both sides); Pump is considered hydraulically balanced but is susceptible to uneven flow on both sides of impeller if suction piping is not done properly.

Based on type of volute:Single volute - pump volute has single lip which is very easy to cast. Is usually used in small low capacity pumps where a double volute design is impractical due to relatively small size of volute passageway which make obtaining good quality commercial casting difficult. Pumps with single volute design have higher radial loads.

Double volute - pump volute has dual lips located 180 degrees apart resulting in balanced radial loads; most centrifugal pumps are of double volute design.

Based on nozzle location:End suction/top discharge - the suction nozzle is located at the end of, and concentric to, the shaft while the discharge nozzle is located at the top of the case perpendicular to the shaft. Pump is always of an overhung type and typically has lower NPSHR because the liquid feeds directly into the impeller eye.

Top/top nozzles -the suction and discharge nozzles are located at the top of the case perpendicular to the shaft. Pump can either be overhung type or between-bearing type but is always a radially-split case pump.

Side/side nozzles - the suction and discharge nozzles are located at the sides of the case perpendicular to the shaft. Pump can either be an axially or radially split case type.

Based on shaft orientation:Horizontal - pump with shaft in horizontal plane; popular due to ease of servicing and maintenance.

Vertical - pump with shaft in vertical plane; ideal when space is limited.

MAIN PARTS OF CENTRIFUGAL PUMP

ImpellerCasingShaftDiffuserSealing Ring

Impeller

An impeller is a rotating component of a Centrifugal pump.

It create suction through which the fluid is drawn. Its made up of iron, steel,bronze, brass,aluminum

or plastic. Impellers are usually have an open inlet (called an

eye) to accept incoming fluid,vanes to push the fluid radially.

Different Types of Impeller

The impeller of a Centrifugal Pump can be of three types:

• Open Impeller: The vanes cast free on both sides. • Semi-Open Impeller: The vanes

are cast free on one side and enclosed on the other.

• Enclosed Impeller: The vanes are located between the two discs, all in a single casting.

SEALING RING

Sealing ring (leakage reduction ring)-Reduce the internal leakage -Delay the impeller and pump casing

DIFFUSER

Diffuser consist of floating ring of stationary guide vanes surrounding

the impeller. Its increase the

efficiency of pump.

CASING

The pump’s casing houses the hole assembly and protects is from harm

The impellers are fitted inside the casings

It is important to reduce friction losses Casings are generally of two types: (1)volute casing (2)circular casing

Volute casings

Volute casings build a higher head. A volute is a curved funnel increasing in

area to the discharge port As the area of the cross-section increases,

the volute reduces the speed of the liquid and increases the pressure of the liquid.

VOLUTE CASING

circular casings circular casings are used for low head and high

capacity. Circular casing have stationary diffusion vanes

surrounding the impeller periphery that convert velocity energy to pressure energy.

circular casings are divided in two way (1)Solid casing (2)split casing

PERMORMANCE CURVE

PRACTICAL CURVE

ACTUAL PERFORMANCE

WORKING PRINCIPLE

Similar to all other pumps, the centrifugal pump also converts one form of energy into another form to operate for pumping fluid.

It principally takes mechanical energy from the motor assembled with the pump, and converts it into either kinetic energy or the potential energy of the fluid movement.

It absolutely depends upon the fluid as to what energy mechanical energy convert into.

The impeller, as indicated earlier, is available in both straight and curved blades/vanes.

The continuous rotation of the fluid creates a pressure within the impeller and this rise in pressure transfers some amount of energy to the discharge end too.

WORKING DIAGRAM (PRINCIPLE)

WORKING OF A CENTRIFUGAL PUMP

A centrifugal pumps converts mechanical energy from a motor to energy of a moving fluid.

Some of the energy goes into kinetic energy of fluid motion, and some into potential energy,

The transfer of energy from the mechanical rotation of the impeller to the motion and pressure of the fluid is usually described in terms of centrifugal force, especially in older sources written before the modern concept of centrifugal force as a fictitious force in a rotating reference frame was well articulated.

The concept of centrifugal force is not actually required to describe the action of the centrifugal pump. In the modern centrifugal pump, most of the energy conversion is due to the outward force that curved impeller blades impart on the fluid. Invariably, some of the energy also pushes the fluid into a circular motion, and this circular motion can also convey some energy and increase the pressure at the outlet.

DIAGRAM OF CENTRIFUGAL PUMP(WORKING)

PRACTICAL APPLICATIONS

To pump the general water supply.To provide booster serviceTo pump the domestic water supplyTo support the fire protection systems.To provide sump drainage

PRACTICAL APPLICATIONS (DIAGRAM)

Advantages

There are no drive seals, therefore the risk of leaks is completely eradicated.

This means that hazardous liquids can be pumped without spillages.

Less heat transfer from the motor—the pump chamber is separated from the motor by an air gap; this provides a thermal barrier.

Complete separation of the liquid means that liquid cannot seep into the motor from the pump.

Reduced friction. Pump has almost have 95% efficiency.

Disadvantages

Cannot be able to work high head. Cannot deal with high viscous fluid. Unexpected heavy load may cause the coupling to

slip. Ferrous particles in liquid are problematic when

you are using magnetic drive. Its one of the disadvantages is its relative poor

suction power.

CAVITATION

EFFECT OF CAVITATION