DEVANGANA SHANDILYA (Design Aspects of Centrifugal Pump)

7/24/2019 DEVANGANA SHANDILYA (Design Aspects of Centrifugal Pump)

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DESI

ASPECTCENTRIF

PUM


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Centrifugal Pump

A centrifugal pump is one of the simplest pieces of equipment in any process plant.

Works on the principle of centrifugal force. This is the force that pushes the liquid away f

tangential direction). Converting Prime over energy into echanical energy through shechanical energy into fluid energy through impeller. Converting kinetic !nergy into pre

the volute casing.


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Main Parts Of Centrifugal Pump


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Centrifugal PumpMajr Parts!

"haft# $t transmit the torque%Power. and supporting the

impeller and other rotating parts. "haft is protected from

erosion &corrosion and wear at the seal cham'er through

renewa'le sleeve.

$mpeller# An $mpeller has vanes that pushes the liquid

through the impeller. Transmit energy into the fluid

(hydraulic energy).

olute%Casing# $mpeller are fitted inside the casing.olute casing is a curved shaped &increasing in cross

sectional area. olute reduces the velocity of the liquid

and increases the pressure.


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Capa"it#Capacity means the flow rate with which liquid is moved or pushed 'y the pump to the desired point in

commonly measured in either gallons per minute (gpm) or cu'ic meters per hour (m %hr).

Imprtant Terms

Q=449*V*A

The pressure at any point in a liquid can be thought of as being caused by a verticliquid due to its weight The height of this column is called the static head and is eof feet of liquid

Head

T$e main reasn fr using $ea% instea% f pressure to measure a centrifugal pump*s energy is that th

pump will change if the specific gravity (weight) of the liquid changes& 'ut the head will not change .

"ead=#pressure* $%&'(speci)c gravity

The "u'scripts &s' refers to suction conditions and &%' refers to discharge conditions.

o "tatic "uction +ead& $S

o "tatic ,ischarge +ead& $%

o -riction +ead& $f

o apor pressure +ead& $(p

o Pressure +ead& $p

o elocity +ead& $(

Various types of head


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o Total "uction +ead )S

o Total ,ischarge +ead )%

o Total ,ifferential +ead )T

o et Positive "uction +ead /equired NPS)r

o et Positive "uction +ead Availa'le NPS)a

NPS) "al"ulatins

0hv 1h

Signifi"an"e f NPS)r an% NPS)aThe P"+ availa'le must always 'e greater than the P"+ required for the pump to operate properly. $t

have at least 2 to feet of e3tra P"+ availa'le at the suction flange to avoid any pro'lems at the duty

P*er an% Effi"ien"#

+ra,e )rse P*er -+)P.The work performed 'y a pump is a function of the total head and the weight of the liquid pumped in a g

Pump input or 'rake horsepower (4+P) is the actual horsepower delivered to the pump shaft.

Pump output or hydraulic or water horsepower (W+P) is the liquid horsepower delivered 'y the pump. T

defined 'y the following formulas.


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The pump e+ciency is the ratio of these two values

,est -+ciency .oint #,-.' is the capacity at ma!imum impeller diameter at whicis highest All points to the right or left of ,-. have a lower e+ciency


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Presssure Rise T$rug$ Impeller

Minimum Spee% Fr Starting A Centrifugal Pump

Ma/imum Su"tin Lift Or Su"tin )eig$t

A'ove equation is a ma/imum su"tin lift r $eig$t0 $f the suction height of pump is more than & t

cavitation.


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Un%erstan%ing Centrifugal Pump Perfrman"e CThe capacity and pressure needs of any system can 'e defined with the help of a graph called a system

capacity vs.pressure variation graph for a particular pump defines its characteristic pump performance


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5. 6Centrifugal pumps operation at off1design conditions7& Chemical Processing April& ay& 8une 59:;

2. 6=nderstanding P"+ for Pumps7& Technical Pu'lishing Co. 59;>& Travis -. ?lover

Referen"es!

% /Controlling Centrifugal Pumps7& +ydrocar'on Processing& 8uly 599>& Walter ,riedger@. =nit operations of chemical engineering & ;thedition 'y macc'e& smith and harrenhall

.riming0 The operation of filling the casing & impeller and suction pipe and the portion of delivery pump up t

priming. $n case the priming of pump is not done and the pump is not done and the pump is not under

present in the pump and suction pipe will flow 'ack to the sump. The space occupied 'y water will $f the pump is now started& the air pockets inside the impeller may give rise to vortices and cause th

=nder these condition& the flow of fluid does not commence and the pump runs dry. $t causes the ru

wearing rings& increases noise level and vi'rations and finally may cause the serious damage to pu Priming for small pumps is done 'y handA foot valve is essential at the 'ottom of suction pipeA funnel or priming cup is provided to fill the water 'y hand. An air vent is provided in the casing o

is filled& the air escapes through the air vent. $t is closed once the priming is completed

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DEVANGANA SHANDILYA (Design Aspects of Centrifugal Pump)