process pump

8/6/2019 Process Pump

1/29

CENTRIFUGAL PUMPCENTRIFUGAL PUMPCENTRIFUGAL PUMPCENTRIFUGAL PUMP

20 October 2005


2/29

Value MomentValue MomentValue MomentValue Moment

20 October 2005


3/29

Value Moment


4/29

Definition

Pumps are machines which provide the energyrequired to transfer liquids from one point toanother.

Due to the incompressibi

lity of

liquids, whichholds true for all practical purposes, all energy

imparted to aliquid by the pumping actiontends to put it in motion.


5/29

Classification

Pump

Centrifugal

Positive Displacement

Reciprocating pump

Rotary pump

Pump pressurizes liquid by means of centrifugal force on itsimpeller, and is widely used in industry.


6/29

Component


7/29

Component (cont)

Two main component :

Rotating

- Impeller

- Shaft

Stationary

- Casing

- Suction and Discharge Nozzle

- Seal Chamber and Stuffing Box

- Bearing Housing


8/29

Working Mechanism


9/29

Working Mechanism

Its purpose is to convert energy ofa primemover (electric motor or turbine) first intovelocity or kinetic energy and then intopressure energy ofa fluid that is beingpumped.

The energy changes occur by virtue of twomain parts of the pump, the impeller and thevolute or diffuser.

The impeller is the rotating part that convertsdriver energy into the kinetic energy.

The volute or diffuser is the stationary partthat converts the kinetic energy into pressureenergy.


10/29

Codes and Standards

API 610, Centrifugal Pump for Petroleum, HeavyDuty Chemicaland Gas Industries Services

API 682, Shaft Sealing System for Centrifugaland Rot

ary P

ump


11/29

What is Important ?

Capacity

Head

NPSH

Power- BHP (Break Horse Power)

- BEP (Best Efficiency Point)

Specific Speed


12/29

Performance Curve

Capacity vs pressure variation graph for aparticular pump

The supplier try to match the system curve

supp

lied by the

user with

apump c

urve th

atsatisfies these needs as closely as possible.

A pumping system operates where the pumpcurve and the system resistance curveintersect. The intersection of the two curves

defines the operating point of both pump andprocess.


13/29

Performance Curve (cont)


14/29

Project

Specification

Datasheet

TBE

Brochure


15/29

Thank YouThank YouThank YouThank You

20 October 2005


16/29

Impeller

Classification :

Based on major direction of flow in reference tothe axis of rotation :

Radial flow ; Axial flow ; Mixed flow

Based on suction type :

Single suction ; Double suction

Based on mechanical construction :

Closed ; Open ; Semi-open or vortex type

The impeller is the main rotating part that providesthe centrifugalacceleration to the fluid.


17/29

Impeller (cont)

The number of impellers determines the number

of stages of the pump.

A single stage pump has one impeller only andis the best for low head services.

A two-stage pump has two impellers in series

for medium head service.

A multi-stage pump has three or more impellers

in series for high head service.


18/29

Shaft

The basic purpose is to transmit the torquesencountered when starting and during operationwhile supporting the impeller and other rotating

parts

Shaft sleevePump shafts are usually protected from erosion, corrosion, andwear at the seal chambers, leakage joints, internal bearings, and inthe waterways by renewable sleeves.

Coupling

Coupling can compensate for axial growth of the shaft and transmittorque to the impeller


19/29

Casing

Two type of casings :

Volute

Circular

Volute casing build a higher head ; circular casings are used for lowhead and high capacity.

One of the main purpose ofa volute casing is to help balancethe hydraulic pressure on the shaft of the pump.

Conventionally, the diffusers are applied to multi-stage pumps.

The impellers are fitted inside the casings.

The casings can be designed either as solid casings or split casings.

Split casing implies two or more parts are fastened together.

Casing wear rings act as the seal between the casing and the

impeller.


20/29

Suction and Discharge Nozzle

The suction and discharge nozzles are part of the

casings itself.

Configurations : Side suction/top discharge

Top suction/top discharge

Side suction/side discharge

Suction nozzle is located at the end of, and concentric to, the shaftwhile the discharge nozzle is located at the top of the caseperpendicular to the shaft

This pump is always ofan overhung type .

The suction

and disch

arge nozz

les

are

loc

ated

at the top of thecase perpendicular to the shaft.


21/29

Seal Chamber and Stuffing Box

Gland is a very important part of the seal chamber or the stuffing

box. It gives the packings or the mechanical seal the desired fit onthe shaft sleeve. It can be easily adjusted in axial direction.

The gland comprises of the seal flush, quench, cooling, drain, andvent connection ports as per API 682.

The primary f

unction is protecting the p

ump

against

leakage

at thepoint where the shaft passes out through the pump pressure casing


22/29

Bearing Housing

The bearing housing encloses the bearingsmounted on the shaft.

The bearings keep the shaft or rotor in correctalignment with the stationary parts under the

action of radialand transverse loads. The bearing house also includes an oil

reservoir for lubrication, constant level oiler,jacket for cooling by circulating cooling water.


23/29

Capacity

The flow rate which liquid is moved or pushedby the pump to the desired point in theprocess.

The capacity

usuall

y changes with the ch

angesin operation of the process.

Unit : - GPM (gallons per minute)

- m3/h (cubic meters per hour)


24/29

Head

A measurement of the height ofaliquidcolumn that the pump could create from thekinetic energy imparted to the liquid.


25/29

NPSH

The total head at the suction flange of the pump

less the vapour pressure converted to fluid

column height of the liquid.

Net Positive Suction Head Required, NPSHr

Net Positive Suction Head Available, NPSHa

A function of the pump design and is determined based on actualpump test by vendor.

The positive head in feet absolute required at the pump suction

to overcome pressure drops d

ue to shock

and t

urbul

enceas theliquid strikes the impeller in the pump and maintain the majority

of the liquid above its vapour pressure.

A function of the system in which the pump operates.

It is the excess pressure of the liquid in feet absolute over its


26/29

Cavitation

A term used to describe the phenomenon whichoccurs in a pump when there is insufficientNPSH Available.

The pressure of the liquid is reduced to a valueequal to or below its vapor pressure and smallvapor bubbles or pockets begin to form. Asthese vapor bubbles move along the impellervanes to a higher pressure area, they rapidly

collapse. Results in impeller damaged, reduced capacity

due to vapor present in the pump.


27/29


28/29

Specific Speed

Non-dimensional design index that identifiesthe geometric similarity of pumps.

Used to classify pump impellers as to their typeand proportions.


29/29

Mechanical Seal

A device used to prevent shaft leakage bymeans of two sealing surfaces, one stationaryand the other rotating in close contact with it.

API 682, Shaft Sealing System for Centrifugaland Rotary Pump

Summary

process pump

Documents