fluid transportation

8/3/2019 Fluid Transportation

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Types of Fluid

Liquids (Non compressible)

Gases (Compressible)



Fluid Transportation

Work needed to increase themechanical energy of a fluid,which in turn can increase theflow rate (velocity), pressure

or elevation of fluid



Fluid Transportation Equipment

• Pumps

• Fans

• Blowers

• Compressors

• Vacuum Ejectors



What are Pumping System?

• 20% of world’s electrical energydemand

• 25-50% of energy usage in someindustries

• Used for

•Domestic, commercial, industrial andagricultural services

•Municipal water and wastewater

services



Objective of Pumping

System

•

Transfer liquid from source todestination

• Circulate liquid around a system



Components of Pumping System

•Main pump components•Pumps

•Prime movers: electric motors, diesel

engines, air system•Piping to carry fluid

•Valves to control flow in system

•Other fittings, control, instrumentation• End-use equipment

•Heat exchangers, tanks, hydraulic

machines



•Head

•Resistance of the

system•Two types: staticand friction

•Static head•Difference inheight between

source anddestination

• Independent of

flow

destination

source

Statichead

Static

head

Flow



• Static head consists of

•Static suction head (hS):Verticaldistance for lifting liquid relative topump center line

•Static discharge head (hD) : verticaldistance between centerline and liquidsurface in destination tank

• Static head at certain pressure

Head (in feet) = Pressure (psi) X 2.31

Specific gravity



Friction head

• Resistance to flow in pipeand fittings

• Depends on size, pipes,

pipe fittings, flow rate,nature of liquid

• Proportional to square of

flow rate• Closed loop system

only has friction head

(no static head)

Frictionhead

Flow



Pumping System Characteristics

In most cases:Total head = Static head + friction head

Systemhead

Flow

Static head

Frictionhead

Systemcurve

Systemhead

Flow

Static head

Frictionhead

Systemcurve



Types of Pumps

• Classified by operating principle

DynamicPositive

Displacement

Centrifugal Special effect Rotary Reciprocating

Internal

gear

External

gear LobeSlide

vane

Others (e.g.

Impulse, Buoyancy)

Pumps

DynamicPositive

Displacement

Centrifugal Special effect Rotary Reciprocating

Internal

gear

External

gear LobeSlide

vane

Others (e.g.

Impulse, Buoyancy)

Pumps



Positive Displacement Pump

Reciprocating

• Piston

• Plunger

• Diaphragm



Positive Displacement PumpReciprocating (Piston & Plunger)



Positive Displacement PumpReciprocating (Axial Piston)



Positive Displacement PumpReciprocating (Radial Piston)



Positive Displacement PumpReciprocating (Diaphragm)



Rotary

• Gear• Lobe

• Screw

• Cam

• Vane

Positive Displacement Pump



Gear Pump



Rotary Gear Pump



Lobe Pump



Screw Pump



Vane Pump



Centrifugal Pumps

• Axial Flow

• Radial Flow• Mixed Flow

• Peripheral



Liquid Flow Path inside a Centrifugal Pump



Casing

Casings are generally of two types:

volute and circular.

Volute casings: B uild a higher head;

Circular casings: Low head and high capacity.



Volute Casing

A volute is a curved funnel

increasing in area to the

discharge port. As the area of thecross-section increases, thevolute reduces the speed of the

liquid and increases the pressureof the liquid.



Circular Casing

Circular casing have stationary

diffusion vanes surrounding the

impeller periphery that convertvelocity energy to pressureenergy. Conventionally, the

diffusers are applied to multi-stage pumps.



Casing



Impeller

The impeller is the main rotating

part that provides the centrifugalacceleration to the fluid.



Impeller-Classification

Based on major direction of flow

in reference to the axis of rotation

Radial flow

Axial flow

Mixed flow




Based on suction type

Single-suction: Liquid inlet on oneside.

Double-suction: Liquid inlet to the

impeller symmetrically from bothsides.




Based on mechanical construction

Closed: Shrouds or sidewallenclosing the vanes.

Open: No shrouds or wall to enclose

the vanes. Semi-open or vortex type.



Impeller Types



Pump Application

Circuit Arrangement Once Through Arrangement



Capacity of Pump

• Stuffing Boxes and packing



Specific Speed Ns

• Specific speed is a measure of thegeometric similarity of pumps. Specificspeed (Ns) is a non-dimensional designindex that identifies the geometric

similarity of pumps.• It is used to classify pump impellers as to

their type and proportions.

• Pumps of the same Ns but of different sizeare considered to be geometrically similar,one pump being a size- factor of the other.

Specific speed Calculation



Specific speed Calculation



Specific Speed Ns

As per the formula, it is defined as

the speed in revolutions per

minute at which a geometricallysimilar impeller would operate if itwere of such a size as to deliver

one gallon per minute flowagainst one-foot head.

Pump input or brake horsepower (BHP) is



Pump input or brake horsepower (BHP) is

the actual horsepower delivered to the pump

shaft

Pump output or hydraulic or water



Pump output or hydraulic or water

horsepower (WHP) is the liquid horsepower

delivered by the pump



Pump Flow vs Head

Centrifugal Pumps Positive DisplacementPumps

Resultant Characteristics of Two Identical



Resultant Characteristics of Two IdenticalCentrifugal Pumps



Leakage


A Typical Manufacturer`s Performance



A Typical Manufacturer s PerformanceCurves



CavitationsIf the pressure drops below the vapourpressure of the fluid being moved, theliquid may vaporize. The bubbles that formcause a volume increase and “chock” the

pump. Then as the pressure is increasedby the pumping action, the bubblesimplode, creating shock waves that can pitand erode the equipment.

• Serious Noise• Vibration



Net Positive Suction Head

NPSH

The difference between the totalsuction head at the suction flangeand the vapour pressure of the

liquid



Leakage



Power

• Electric Motor

• Steam Turbine

• Gas Turbine

• Diesel Engine



Leakage




The Affinity Laws

The mathematical expressions thatdefine changes in pump

o Capacity,

o Head

o BHP

when a change is made to pumpspeed, impeller diameter, or both.

Th Affi i L



The Affinity Laws

Capacity, Q changes in directproportion to

o Impeller diameter D ratio, or

oSpeed N ratio

Q2 = Q1 x [D2/D1]

Q2 = Q1 x [N2/N1]

Th Affi i L



The Affinity Laws

Head, H changes in direct proportionto the

oSquare of impeller diameter D

ratio, oroSquare of speed N ratio

H2 = H1 x [D2/D1]2

H2 = H1 x [N2/N1]2

Th Affi i L



The Affinity Laws

Brake Horse Power, BHP changes indirect proportion to the

oCube of impeller diameter D ratio,

oroCube of speed N ratio

BHP2 = BHP1 x [D2/D1]3

BHP2 = BHP1 x [N2/N1]3



The Affinity Laws

If changes are made to bothimpeller diameter and pump speedthe equations can be combined to:

• Q2 = Q1 x [(D2xN2)/(D1xN1)]

• H2 = H1 x [(D2xN2)/(D1xN1)]2

• BHP2 = BHP1 x [(D2xN2)/(D1xN1)]3

fluid transportation

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