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HALDIA PETROCHEMICALS LIMITED

TRAINING PERIOD: 18.05.2015 – 17.06.2015

Report on:

Under the guidance of

Mr. Yuvaraj Elumalai

Manager, IOP, HPL

and

Mr. Sanjoy Kumar Dey

Deputy Manager, IOP, HPL

By

Subham Shit

Mechanical Engineering Department

Indian Institute of Engineering Science and Technology, Shibpur

Howrah – 711103.

Discussion on Pumps used in IOP

(Integrated Offsite and Utilities Plant)

Acknowledgement

I would sincerely like to thank the Human Resource Department, of Haldia

Petrochemicals Ltd. for their constant assistance to help me achieve this training

successfully. My sincere regards to Mr. Badal De, DGM of IOP Deparment for

helping me realise the dos and don’ts pertaining to this specific training report

under IOP and also helping me in all other sort of ways throughout the entire

duration of my work. I would like to thank Mr. Yuvaraj Elumalai, Manager, IOP

who opted to become my training guide and it was owing to him that my training

has become a success. I would also like to thank Mr. Sanjoy Kumar Dey (Deputy

Manager, IOP), Mr. Rakesh Ranjan (Assistant Manager, IOP), Mr. Sudipta Sarkar,

Mr. Srinath Mohanty and Mr. Gaurav Paul (all Engineers of IOP) for their sincere

help, guidance and hours of teaching and learning I gained from them that I have

finally been able to jot down this training report. I am sincerely indebted to

specially Mr. Sudipta Sarkar & Mr. Srinath Mohanty, for the large chunks of time

they spent every now and then to answer all of my doubts and questions and

scrutinise my report, pointing my mistakes and guiding me to the correct path.

Lastly, I would like to thank all other various members and workers of IOP, who

have helped me in one way or another during this month-long training.

Subham Shit

Summer Trainee, Haldia Petrochemicals Ltd.

Mechanical Engineering Department IIEST, Shibpur

C O N T E N T S 1. CHAPTER 1: A REPORT ON IOP

1.1 Introduction 1

1.2 NCR (North Control Room) 1

1.2.1 Cooling Water System

1.2.2 Water Treatment System

1.2.3 DM Water System & CPS

1.2.4 Compressed Air System

1.2.5 Naphtha Tanks

2

3

5

6

7

1.3 ECR (East Control Room) 8

1.3.1 Gantry Loading and Unloading System

1.3.2 Tank, Sphere and Bullet Storage Systems

8

9

1.4 SCR (South Control Room) 12

1.4.1 Waste Water Treatment Plant (WWTP)

1.4.2 Flare System

12

14

2. CHAPTER 2 : PUMPS IN IOP

2.1 Introduction 15

2.2 Classification of Pumps 15

2.2.1 Classification of Dynamic Pumps

2.2.2 Classification of Displacement Pumps

15

16

2.3 Cavitation 16

2.3.1 What is Cavitation?

2.3.2 Source of Cavitation

2.3.3 Cavitation types and its prevention

16

16

17

2.4 Net Positive Suction Head (NPSH) 19

2.4.1 What is NPSH?

2.4.2 Requirement of NPSH

2.4.3 Difference between NPSHA and NPSHR

19

20

20

2.6.1 Function of Casing

2.6.2 Types of Casing

23

24

24

2.8.1 Introduction

2.8.2 Basic Components

2.8.3 Types of Mechanical Seal & Applications

2.8.4 Advantages and Disadvantages of Mechanical Seal

2.8.5 Different Types of Plans

26

26

26

27

27

REFERENCES 39

2.5 Types of Impeller 21

2.6 Pump Casing

2.7 Suction Piping 24

2.8 Mechanical Seal 26

2.9 Performance Curve of Centrifugal Pumps 29

2.10 Pumps in IOP 30

A REPORT ON IOP Integrated Offsite and Utilities Plant

A B S T R A C T

This report consists of

description about three

controlling units under IOP

along with their systematic

operations on various systems

with different flow diagrams.

CHAPTER 1

1

IOP (Integrated Offsite and Utilities Plant)

1.1 Introduction

1.2 NCR (North Control Room)

Under North Control Room (NCR) the following activities are done.

NCRCooling Water System

(Supping Cooling water throughout all heat exchangers of HPL where water is used as coolant)

DM Water System and Condensate Polishing System

(De-Mineralized Water Production and supply)

Raw Water Treatment Plant

(Supplying high quality water for cooling tower make-up)

Pre-treatment Plant

(Supplying high quality water for DM Plant feed)

RO Plant

(Water treatment using Reverse Osmosis Process)

Compressed Air System

(Supplying Instrument Air and Plant Air)

Steam Distribution System

(Suppling Stream and Power from Captive Power Plant[CPP])

Raw Material Storage System

(Storage of Process Grade Naphtha in Naphtha Tanks)

IOP (Integrated Offsite & Utilities Plant) comprises of three basic controlling departments or

sections - NCR (North Control Room), ECR (East Control Room) and SCR (South Control

Room). These sections each consists of some sub-divisions. NCR consists of cooling water

system (Cooling Towers & Mist Cooling System), DM water Plant, RO Plant, Water Treatment

Plant, Pre-treatment Plant, Compressed Air Distribution System and Stream Distribution

System. ECR has Gantry loading and unloading system, Tank, Sphere & Bullet Storage and

Transport for different types of materials (Raw material, intermediate and finished product).

SCR consists of Waste water treatment plant and Flare System.

2

1.2.1 Cooling Water System

Basic Description:

Cooling water is used to remove unwanted heat from industrial manufacturing processes.

Temperature is one of the most critical parameter of concern in any chemical process

industry.

Cooling water system basically consists of:

a. Cooling water basin and sump

b. Circulating Pumps

c. Hot Water Channel and distribution system.

d. Packing for heat transfer

e. Fan

f. Supply & return Header

g. Side stream filter.

Temperature reduction takes place by evaporation of equivalent quantity of water.

Corrosion, scale deposition and microbial growth are the major points of concern in cooling

water system. To control it, sulfuric acid, chlorine, corrosion inhibitor, scale dispersant,

biocide and bio-dispersant are dosed under cooling water treatment program.

Equipment(s) in cooling water system:

In HPL, we have 1 no. of Mist Cooling System and 2 nos. of cooling towers to cater the

demand of cooling water in NCU, NCAU and polymer plants separately.

Cooling Tower - 01

o Caters to the demand of cooling water in NCU, NCAU and CCR & Olefin Building.

o 9 cells of capacity 3500 m3/h each.

o Range: 120C, Approach: 60C, Efficiency: 68.5%

o Nine pumps (7W+2S) of capacity 4500 m3/h circulate the water to the plants.

o Side stream filters have been provided to control the suspended particles in the circulating water.

Cooling Tower - 02

o Caters to the demand of cooling water in HDPE, LLDPE, PP and all IOP control rooms.

o 7 cells of capacity 3500 m3/h each.

o Range: 80C, Approach: 50C, Efficiency: 63%

o Six pumps (5W+1S) of capacity 4500 m3/hr circulate the water to the plants.

o Side stream filters have been provided to control the suspended particles in the circulating water.

Mist Cooling System

o Caters to the demand of cooling water in all associated units.

o Total no. of nozzles: 5 (Nozzles in 1 Nozzle Arrangement) × 23 (Nozzle Arrangements in one 6’’ header) × 10 (No. of 6’’ headers) = 1150 with spiral holes for spin flow.

o The nozzles spraying hot water vertically into the atmosphere (Evaporative cooling).

o Range: 7 – 8 0C.

3

Flow Diagram of cooling water system:

1.2.2 Water Treatment System

The water treatment system can be classified or represented in the following form.

Cooling Water Sump

Side Stream Filters

Acid

Chlorine

Corrosion Inhibitor + Non-oxidizing Biocide + Scale Dispersant + Bio-dispersant

Makeup water

Return Header

Supply Header

Raw

Wat

er

Storage in Ponds

Water Treatment Plant

CT - 01

CT - 02

CT - CPP

CT - Praxair

Drinking Water

Pre Treatment PlantDM Plant

& CPU

Plant Water System

Fire Water System

4

Raw Water Treatment Plant & Pre Treatment Plant:

Raw water is used for cooling water makeup, DM plant feed, plant water, drinking water and

fire water in our plant. Raw water is received from PHED through dedicated pipelines. Although

it is a filtered water, it may not meet the stringent standard for using it directly in cooling water

makeup and DM plant feed. Raw water treatment plant and pre-treatment plant has been

provided to supply high quality water for cooling tower make-up and DM plant feed

respectively.

o Capacity of Raw Water Treatment Plant – 2600 m3/h.

o Capacity of Pre-treatment Plant – 500 m3/h

Pre-chlorination, chemical coagulation and flocculation, clari-flocculator/reactor clarifier

and high rate gravity sand filters have been provided to control biological growth and reduce

suspended solids and turbidity to acceptable levels.

Raw Water and Treated Water Characteristics:

Flow Diagram of Raw Water Treatment Plant:

Raw Water Treatment Plant Pre-Treatment Plant

Feed Water Treated Feed Water Treated

pH 7.5-8.5 7.5-8.5

pH 7.5-7.7 7.5

Turbidity, NTU 100-200 < 1.0

TSS, mg/L 300 (max.) < 5 TSS, mg/L 100 (max.) < 0.5

Stilling Chamber Flash Mixer Parshall Flume

Sand Filter Clari-flocculator

Filtered water for CT-makeup, DM Plant & Drinking Water

Chlorine Lime + Alum

Polyelectrolyte

5

1.2.3 DM Water System & CPS

Basic Description:

Natural water contains dissolve salts like carbonates, bicarbonates, sulfates and chlorides of

Calcium, Magnesium and Sodium and other impurities like silica, metals etc. Some of these salts

have very low solubility in water at higher temperatures. When water is to be heated with in a

boiler for steam generation, scale forms due to deposition of low solubility salts. e.g.

Ca(HCO3)2

∆→ CaCO3 + H2O + CO2

Water is also used directly in the process in polymer plants. Any contamination may

adversely affect the quality of product. Complete removal of all dissolved salts is necessary in

the above cases. DM (De-mineralization) water plants remove these salts by passing it through

different resin beds (Cation and anion). These resins remove the cations (Ca+2, Mg+2) and anions

(Cl-, SO4-2) by replacing them with free ions. Ion exchange resins are porous materials which

contain an inert base attached to which, are free ions. These ions are free to move about within

the resin structure and can be replaced by other ions of the same type from a surrounding

solution.

Flow Diagram of DM Water Plant:

Full Forms:

ACF - Activated Carbon Filter, WAC - Weak Acid Cation Exchanger, SAC - Strong Acid Cation Exchanger, WBA – Weak Base Anion Exchanger, SBA – Strong Base Anion Exchanger, MB – Mixed Bed Exchanger.

WBA

DM Water Tank

ACF WAC SAC Degasser Tower

SBA MB

For Distribution

Pre-treated Water

6

Flow Diagram of Condensate Polishing System(CPS):

1.2.4 Compressed Air System

Compressed Air System is one of the basic systems in the plant. It supplies plant air and

instrument air which is very necessary for many instruments used in the polymer units.

Equipment(s) in compressed air system:

o 3 Stage Centrifugal Air Compressor (with water intercoolers between 2 consecutive

stages) – 3 units.

o Single acting, double stage, double cylinder Reciprocating Air Compressor – 1 unit.

o Plant Air Receiver

o Instrument Air Dryer

o HP Air Compressors

o HP Air Receiver

The compressed air system is a high noise zone area. In the three 3 stage centrifugal compressors air is first compressed in the 1st centrifugal compressor (low pressure, stage 1) then it comes inside the 1st intercooler and then it is compressed in the 2nd centrifugal compressor (medium pressure, stage 2) and it comes inside the 2nd intercooler and then it is compressed in the 3rd centrifugal compressor (high pressure up to 7.6 kg/cm2, stage 3). After that the high pressurized air comes into the air receiver. The compressed air is then divided into two parts one is for producing plant air and another is for instrument air. For plant air, the hot compressed air is again cooled by cooling water and for instrument air, the hot compressed air is passed through air dryer (using activated Alumina). Thus by removing moisture, instrument air is produced.

Generally, Air receiver has pressure 24.5 kg/cm2 (usually it varies 25-29 kg/cm2) as maintained by the process. If the pressure in air compressor falls below 25 kg/cm2, the reciprocating air compressor becomes active automatically and it pressurizes the air receiver up to 28 kg/cm2. This is the main function of the Reciprocating air compressor.

DMW CWS

Raw Condensate

Condensate/DMW Exchanger

Trim Cooler Condensate Tank

Activated Carbon Filter

Filter Mixed bed Exchangers

DM Water

7

Flow Diagram of Compressed Air System:

1.2.5 Naphtha Tanks

Naphtha Tanks are used for storing process grade naphtha.

Roof Appurtenances: Level Transmitter (both Servo Type & Float Type), Deck Manhole (with

ladder), Rim vent (with wire mesh), Emergency drain, Bleeder vent, Manway in each

compartment, Gauge hatch with cover. Shell Appurtenances: Manhole, Product inlet/outlet,

Siphon drain, Roof drain, Foam connection.

CWS Plant Air Receiver

Instrument Air Dryer Desiccant: Activated Alumina

Air Compressors

HP Air Compressors

HP Air Receiver

Plant Air Distribution

Instrument Air Distribution

Fig. 1.3.2: Diagram of Naphtha Tank (41-T-001 A/B/C/D)

Source: Haldia Petrochemicals Ltd.

8

1.3 ECR (East Control Room)

Under East Control Room (ECR) the following activities are done.

1.3.1 Gantry Loading and Unloading System

The tanks which are used for transporting hydrocarbons from one place to another is unloaded and loaded in this system. Specifically, this system has reciprocating compressors (like – Corken Gas Compressor).

The entire gantry loading and unloading system can be classified or represented in the following form.

ECRGantry Loading and Unloading System

(This System is basically used to load and unload the tanks used for hydrocarbon transport)

Tank, Sphere and Bullet Storage Systems

(Depending upon the vapor pressure of the liquid at atmospheric temp different types of storage is used)

Transport for different types of materials

(Raw material, intermediate and finished product transport)

MS Production

(Motor Spirit is produced in ECR)

Gan

try

Lo

adin

g a

nd

Un

load

ing

Sys

tem

Pressurized Gantry

Unloading Bay

(Raw Material)

LPG, Propylene

(Vertical Multistage Barrel Type

Centrifugal Pump)

Propylene Unloading (Corken Compressor)

Fuel Gas Naphtha (FGN) Unloading

Butene-1 Unloading

Loading Bay

(Product)

LPG/C4 Raffinate

Butadiene

Non-Pressurized Gantry

Unloading Bay

(Raw Material)Hexane Unloading

Loading Bay

(Product)

MS (Motor Spirit)

PY Gas

CBFS (Carbon Black Feed Stock)

Benzene

9

1.3.2 Tank, Sphere and Bullet Storage Systems

Requirement of different type of storages:

Depending upon the vapour pressure of the liquid at atmospheric temp different types of storage is required.

o If vapour pressure is > 1 kg/cm² liquid is to be stored in sphere or bullet.

o If 0.5 kg/cm² < vapour pressure < 1 kg/cm² liquid is to be stored in doom roof tank.

o If vapour pressure < 0.5 kg/cm² liquid is to be stored in atmospheric tank.

Why Sphere, Bullet and Tank shapes are used for storage devices?

Generally, Spheres are constructed at the place of installation because of its huge size and difficulty to transfer from one place to another. As in HPL, a sphere needs 12 no. of columns for its support at the ground. In spite of having these problems regarding sphere, it is used in large no. for storing raw materials (41-V-001, 41-V-002A/B/C), intermediate products (42-V-

001A/B/C/D, 42-V-003A/B/C/D) and finished products (43-V-001A/B/C/D, 43-V-002A/B/C/D). The basic reason behind this is that for a sphere the hoop stress (𝜎ℎ) and the meridional stress (𝜎𝑚) are equal. This value is given by:

𝜎ℎ

𝑟+

𝜎𝑚

𝑟=

𝑝𝑖

𝑡𝑠𝑝 ⇒ (σmax)sphere =

pid

4𝑡𝑠𝑝

Now, for a cylinder (or tank), longitudinal stress (𝜎𝑙) is half of the hoop stress (𝜎ℎ). This can be derived as:

𝜎ℎ

𝑟+

𝜎𝑙

∞=

𝑝𝑖

𝑡𝑐𝑦 ⇒ (σmax)𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 =

pid

2𝑡𝑐𝑦

𝜎𝑙 ∙ 2𝜋𝑟𝑡𝑐𝑦 = 𝜋𝑟2𝑝𝑖 ⇒ 𝜎𝑙 =p

id

4𝑡𝑐𝑦

So, we can clearly say if a sphere and a cylinder of same material with same diameter is subjected to same internal pressure, then the required thickness of the sphere (𝑡𝑠𝑝) will be half

of the thickness of the tank (𝑡𝑐𝑦).

Putting it another way, a sphere of same material with same diameter and thickness of a cylinder can sustain twice of the internal pressure developed in the cylinder. So, sphere is better than a cylinder in case of material usage point of view. But, construction or manufacturing cost is more in case of a sphere compared to a cylinder or tank.

For utilizing both transportability & maximum stress along with less construction cost, bullet type structures are made. Bullet is nothing but a cylinder with two thin hollow hemi-spherical ends. Bullet can be moved from one place to another and as per HPL, bullets are at high pressure (150 kg/cm2, gauge) while spheres are pressurized at 25-27 kg/cm2 (gauge). But while manufacturing of a bullet there may have some problems regarding the joining of two different thicknesses at the two ends.

Fig. 1.3.2: Schematic Diagram of a Bullet Storage

10

Storage Classifications:

N2 Blanketing is nothing but pressurising with nitrogen gas inside a closed tank. The nitrogen blanketing is done by operating two valves: PSV (Pressure Safety Valve) & VRV (Vacuum Release Valve). The reason behind the nitrogen blanketing is for safety purpose. Generally, the vapour pressure of liquid hydrocarbon is near atmospheric pressure. So, vapour generation can happen in normal temperature and pressure and the concentrated vapour linkage may lead to fatal accident. To avoid that, the liquid hydrocarbons must be pressurised by any inert gas like nitrogen. As little leakage cannot be avoided, it is better to be diluted with N2 because diluted hydrocarbon vapour will be less accident-prone. This is main reason of using nitrogen blanketing.

Suppose, in a Dome Roof Tank or Internal floating roof tank, if the liquid hydrocarbon level decreases i.e. if floating roof (for Internal floating roof tank) falls down, as a result the nitrogen inside the chamber will expand. So, the available nitrogen pressure inside the chamber will decrease and if pressure reduces below atmospheric pressure, the tank may undergo plastic deformation due to pressure difference between the inside & outside surface. To avoid this, VRV (Vacuum Release Valve) is used here. It supplies extra amount of nitrogen inside the tank which maintains the pressure accordingly. On the other side, if the liquid hydrocarbon level increases then the chamber will be pressurized, so it can be damaged. To avoid that, PSV (Pressure Safety Valve) is used. It reduces the pressure by releasing nitrogen & hydrocarbon mixture from the tank. This is the main process of nitrogen blanketing.

Typ

es o

f st

ora

geHigh Pressure

Bullet

(for Propane, Hydrogen)

Medium Pressure

Sphere

(for Propylene, Ethylene, Butadiene, C4 Mix, C4Raffinate/ Mix Butane,

Butene-1 etc.)

Low Pressure

Low pressure tank

Dome Roof Tank

[for Cyclopentane, RPG, HPG etc (some are with 0.2 Kg/cm2

N2 blanketing)]

Atmospheric tank

External Floating roof

(for Naphtha, old MS etc.)

Cone roof

(for CBFS, Acid, Caustic storage etc.)

Cone roof & IFR tank with N2 blanketing

(for Benzene, BEU feed stock etc.)

Cone roof & IFR tank without N2 blanketing

(for New MS, imported Hexane, FGN etc.)

What is N2 Blanketing? Why is it used?

11

Different types of Tanks:

Butadiene chilling system:

*Propylene Compressor is one of the critical equipment in IOP, used in Butadiene chilling system (vapour compression refrigeration system using propylene as refrigerant). Another critical equipment is H2 Compressor (Vertical type diaphragm compressor) used for storing H2 coming from NCAU at a pressure 30 kg/cm2g to about 120 kg/cm2g in H2 Storage system (2 no. of bullets).

Floating roof Internal Floating roof

N2

PCV

Internal Floating roof with N2 blanketing

PT

PIC

N2

FY

VRV

PSV

DOME ROOF TANK

To gantry

HX

KO

D

Propylene

compressor*

(Double Acting, Single Stage, double cylinder Reciprocating compressor)

CW

LIC

Vapour balance header

Propylene condenser

Propylene accumulator

12

1.4 SCR (South Control Room)

The main aim of SCR is pollution control. A Petrochemical Industry can have two types of harmful wastes: one is waste water and another is excess hydrocarbons. So, it is mandatory to convert these harmful wastes to treated wastes or certain compounds which will not pollute the environment up to a certain limit as per given by the pollution control board.

Under South Control Room (SCR) the following activities are done.

1.4.1 Waste Water Treatment Plant (WWTP)

General Description:

WWTP has been designed to treat all the liquid effluent generated during process and otherwise from all process plants and IOP.

Plant has been designed to treat-

o Process effluent – 3600 m3/d

o Sanitary Effluent – 490 m3/d

o Cooling Tower Blowdown – 26,220 m3/d

o DM Neutralization Waste – 2000 m3/d

Major pollutants in the liquid effluent are –

o Suspended solids

o Free and emulsified oil

o Sulfide

o Phenols

o Dissolved/Soluble organic material exerting BOD/COD.

Treatment scheme consists of -

o Physical processes to remove free oil, floating particles and suspended particles.

o Physico-chemical processes for pH adjustment, coagulation and flocculation, sulfide removal, de-emulsification of oil and subsequent removal by DAF process.

o Biological process such as Activated sludge process for removal of bio-degradable organics.

o Sludge collection, thickening and centrifugation.

o Slop oil collection and storage.

Full Forms:

o WWF : Wet Weather Flow

o DAF : Dissolved Air Flocculation

o CTBD : Cooling Tower Blow Down

o DOPE : De-Oily Poly-Electrolyte

o TPI : Tilted Plate Inter-separator

o DWPE : De-Watering Poly-Electrolyte

o DAP : Di-Ammonium Phosphate

SCRWWTP

(Waste Water Treatment Plant)

Flare System

(Combustion of excess hydrocarbons)

13

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14

1.4.2 Flare System

Flare system has been provided for disposing hydrocarbon vapors/gases safely by burning at the top of flare stack. Flare system consists of –

o Flare header- For collecting vapors/gases from process units, sphere farm and gantry.

o Flare Knockout Drum – To remove/collect entrapped liquid droplets in flare vapor stream.

o Water Seal Drum – To maintain positive pressure in the flare header by means of water seal.

o Flare Stack – To carry the gases to sufficient height for safe dispersion.

o Molecular Seal – To reduce purge gas consumption.

o Flare Tip – Consists of pilot burners for continuous burning, steam for smokeless flaring.

o Flame Front Generator - For remote lighting up the burner of flare tip.

o Blowdown Pumps – To transfer oil from KOD to storage tank.

Fuel gas is provided to pilot burner for continuous burning. Nitrogen purging is done from all dead ends of flare header to avoid vacuum formation and air ingress. Steam is used for smoke suppression. 74” dia. header has been provided to collect flare gases.

o Design Load – 1286 MT/hr.

o Smokeless flare load – 100 MT/hr.

o Total height of the flare stack – 120 m

Schematic Diagram of Flare System:

****

WSD

Stack

Mol. Seal

Flare Tip

Steam for smokeless combustion

Flame Propagation Lines – 4 nos.

Fuel Gas Supply – 4 nos.

Oil to WWTP

From Process Plants + Gantry etc.

Plant Water

KOD

PUMPS IN IOP Centrifugal Pumps & Reciprocating Pumps

A B S T R A C T

Generally Centrifugal pumps are

the mostly used pumps in IOP. It

has broad applications in different

sectors for better reliability with

low head & high discharge. Beside

this, Reciprocating Pumps also

used in IOP (for chemical dosing

purposes). It has comparatively

less use than Centrifugal Pumps.

CHAPTER 2

15

Pumps in IOP

2.1 Introduction

Pumps are mechanical devise that impart energy to a fluid. Being a hydraulic machine, it converts mechanical energy to hydraulic energy or pressure energy. Pump is a very common machine used in several industries (like: thermal power plant, petrochemical plants etc.) wherever liquid transfer is required.

2.2 Classification of Pumps Pumps may be classified on the basis of the applications they serve, the materials from which they are constructed, the liquids they handle, and even their orientation in space. All pumps may be divided into two major categories: (1) Roto-Dynamic Pumps, in which energy is continuously added to increase the fluid velocities within the machine to values greater than those occurring at the discharge so subsequent velocity reduction within or beyond the pump produces a pressure increase, and (2) Positive Displacement Pumps, in which energy is periodically added by application of force to one or more movable boundaries of any desired number of enclosed, fluid-containing volumes, resulting in a direct increase in pressure up to the value required to move the fluid through valves or ports into the discharge line.

2.2.1 Classification of Roto-Dynamic Pumps

Ro

to-D

ynam

ic P

um

ps

Centrifugal

(Liquid handled: Clean, clear; dirty, abrasive;

slurries,

Operation: Low head, high dischage Steady

Flow)

Axial Flow

Stage BasisSingle Stage

Multi Stage

Impeller BasisOpen Impeller

Fixed Pitch

Variable PitchClosed Impeller

Mixed Flow, Radial Flow

Suction BasisSingle Suction

Double Suction

Stage Basis

Self Priming

Non-Priming

Single Stage

Multi Stage

Impeller Basis

Open Impeller

Semi-open Impeller

Closed Impeller

Peripheral

Stage BasisSingle Stage

Multi Stage

Priming BasisSelf Priming

Non-Priming

Special Effect

Jet (Eductor)

Gas Lift

Hydraulic Ram

Electromagnetic

16

2.3 Cavitation

2.3.1 What is Cavitation?

Cavitation is defined as the process of formation of the vapour phase of a liquid when it is subjected to reduced pressures at constant ambient temperature. Thus, it is the process of boiling in a liquid as a result of pressure reduction below the vapour pressure of the liquid rather than heat addition. However, the basic physical and thermodynamic process are same in both cases.

A liquid is said to cavitate when vapour bubbles form and grow as a consequence of pressure reduction. When the phase transition results from hydrodynamic pressure changes, a two-phase flow composed of a liquid and its vapour is called cavitating flow.

2.3.2 Source of Cavitation

A common source of cavitation is the frictional loss incurred in the suction line between the suction source and a pump. A long suction line, or one with numerous turns or restrictions, can cause sufficient pressure drop to result in cavitation as the liquid enters the pump. In a centrifugal pump, the liquid is most likely to vaporize in the eye of the impeller, near the vane tips. In a reciprocating pump, the liquid is most likely to vaporize in the pumping chamber between the suction and discharge valves at the face of plunger or piston during the suction stroke.

Po

ssit

ive

Dis

pla

cem

ent

Pu

mp

Reciprocating

(Discharge Flow: Pulsating

Operation: High Head, low discharge

Use: Dosing & Pressuring Vessels

[ex. during hydrotest])

Piston, Plunger

(Liquid handled: Clean and

clear)

Steam - Double Acting

Simplex

Duplex

Power

Acting Basis

Single Acting

Double Acting

Structure Basis

Simplex

Duplex

Triplex

Multiplex

Diaphram

(Liquid handled:

Clean, clear; dirty,

abrasive; slurries)

Operation BasisFluid Operated

Mechanically Operated

Structure BasisSimplex

Multiplex

Rotary

(Liquid handled: Viscous, non-

abrasive

Operation: High Head, Low

Dischage, Steady Flow

Use: Lubricating Oil Pumps)

Single Rotor

Vane

Piston

Flexible Member

Peristaltic

Screw

Multiple Rotor

Gear

Lobe

Circumferential Piston

Screw

2.2.2 Classification of Positive Displacement Pumps

17

2.3.3 Cavitation types and its prevention

Types of pump cavitation

A. Vaporization cavitation, also called inadequate NPSHA cavitation.

B. Internal recirculation cavitation.

C. Vane passing syndrome cavitation.

D. Air aspiration cavitation.

E. Turbulence cavitation.

A. Pump cavitation due to vaporization

It’s called “classic Cavitation”. According to Bernoulli’s Law, when velocity goes up, pressure goes down. Centrifugal pump works by acceleration and imparting velocity to the liquid in the eye of the impeller. Under the right conditions, the liquid can boil or vaporize in the eye of the impeller. When this happens we say that the pump is suffering from vaporization cavitation. This type of cavitation is also called inadequate NPSHA cavitation. To prevent this type of cavitation, the NPSHA in the system (the available energy in the system), must be higher than the NPSHR of the pump (the pump’s minimum energy requirement).

To prevent cavitation due to vaporization

NPSHA > NPSHR (safety margin)

1. Lower the temperature of the liquid (decreasing the temperature of the liquid decreases the saturation pressure, causing NPSHA to increase).

2. Raise the liquid level in the suction vessel (increases suction pressure).

3. Change the pump.

4. Reduce motor RPM if possible (Reduces NPSHR).

Fig. 2.3.3.A: Cavitation

due to vaporization

Fig. 2.3.2: Source of Cavitation Source: The Duriron Co. Inc., Pump Engineering Manual, 5th edition, ©1980, Fig. 5.1, page 64

18

5. Increase the diameter of the eye of the impeller.

6. Reduce the head losses by increasing the pipe diameter, reducing the number of elbows, valves, and fittings in the pipe, and decreasing the length of the pipe (Increases NPSHA).

7. Reduce the flow rate through the pump by throttling a discharge valve (decreases NPSHR).

8. Use an impeller inducer.

9. Use two lower capacity pumps in parallel.

10. Use a booster pump to feed the principal pump.

B. Pump Cavitation by Internal circulation

This is a low flow condition where the discharge flow of the pump is restricted and the product cannot leave the pump. The liquid is forced to recirculate from high pressure zones in the pump into low pressure zones across the impeller. This type of cavitation originates from two sources. First, the liquid is circulating inside the volute of the pump at the speed of the motor and it rapidly overheats. Second, the liquid is forced to pass through tight tolerances at very high speed the heat and the high velocity cause the liquid to vaporize.

To prevent pump cavitation due to internal circulation

This condition cannot be corrected on pumps with an enclosed impeller.

1. Open the restricted discharge valve on the pump.

2. The problem could be a clogged downstream filter.

3. A closed discharge valve.

4. An over-pressurized header.

5. Check valve installed backwards

6. Operating the pump at or close to shutoff head.

C. Pump Cavitation due to vane passing syndrome

The free space between the impeller blade tips and the cutwater should be 4% (according to Enggcyclopedia) of the impeller diameter. This type of cavitation is caused by use of a larger diameter impeller or from re-metalizing or coating the internal housing of the pump. For smaller spaces, the liquid velocity between these spaces becomes very high. This high liquid velocity leads to low pressure, heating, bubble formation and hence cavitation. With the pump disassembled the damage is seen on the blade tips at the OD of the impeller and just behind the cutwater on the internal volute wall.

To prevent pump cavitation due to vane passing

To prevent damage due to such cavitation, free space between the impeller blade tips and the cutwater should be at least 4% of the impeller diameter. For example, for a 10” impeller, the free space should be 4% of the impeller diameter between the blade tips and the cutwater. 10” x 0.04

= 0.4”.

D. Pump cavitation due to air aspiration

Air can be drawn into the piping and pump from diverse forms and different points. Air can enter into the piping when the pump is in vacuum, through following routes:

Fig. 2.3.3.B: Cavitation

by Internal Circulation

Fig. 2.3.3.C: Cavitation due to vane

passing syndrome

19

o Through pump shaft packing.

o Valves stem packing on valves in the suction piping.

o Joint rings on suction piping.

o Flange faces sheet gaskets at pipe joints.

o O-rings and threaded fittings on instrumentation in the suction piping.

o O-rings and other secondary seals on single mechanical seals.

o The faces of single mechanical seals.

o Air can also enter into the pump from bubbles and air pockets in the suction piping.

o Liquids that foam can introduce air into the pump.

To prevent pump cavitation due to air aspiration

1. Tighten all flange faces and gaskets.

2. Tighten all pump packing rings and all valve stem packing on suction piping.

3. Keep the velocity of the fluid in the suction piping at less than 8 ft. per second. It may be necessary to increase the diameter of the pipe.

4. Consider using dual mechanical seals with a forced circulation barrier fluid.

E. Pump cavitation due to turbulence

Turbulent flow leads to formation of vortexes in pump suction. Inadequate piping, sharp elbows, restrictions, filters and strainers in suction line contribute to turbulence. The waterfall effect in suction vessels is another contributing factor to pump turbulence.

To prevent pump cavitation due to excess turbulence in suction line

1. Design the pump suction piping and routing to avoid excess turbulence.

2. Take precaution while fixing the pump suction line size to avoid turbulence and have sufficient NPSHA.

3. Respect the maximum allowable flow limit of the pumps.

2.4 Net Positive Suction Head (NPSH)

2.4.1 What is NPSH?

Local reduction of the static pressure p to the vapour pressure pv of the liquid causes

vaporization of the liquid and cavitation. Internal pressure drops are due to a) impeller inlet velocity head and inlet passage loss and b) blade loading and loss within the impeller. In order to prevent a substantial decrease of impeller pressure rise, the sum of these pressure drops should not exceed the difference between Pin (inlet pressure) and p

v, the head equivalent of

which is called “net positive suction head” or NPSH:

Pin − pv

ρg≡ NPSH ⟹ Pin = ρgNPSH + p

v

If P1 be the total pressure at the impeller eye then,

P1 − Pin = ∆Pin (Inlet Pressure loss, negligible)

P1 = p1

+ ρV1

2

2+ ρgZe,1 = Total Suction Pressure

Where, p

1 = Absolute pressure at the impeller eye

V1 = Velocity of the liquid at the inlet Ze,1 = Elevation height (ft. or m) of the inlet or impeller eye

ρ = Density of the liquid.

20

NPSH =P1 − p

v

ρg=

𝑃1

ρg−

pv

ρg= Total Suction head(hs) − vapour head(hv)

2.4.2 Requirement of NPSH

The low pressure at the suction side of a pump can encounter the fluid to start boiling with reduced efficiency, cavitation, and damage of the pump as a result. Boiling starts when the pressure in the liquid is reduced to the vapor pressure of the fluid at the actual temperature. Pump cavitation occurs when the pressure in the pump inlet drops below the vapour pressure of the liquid. Vapour bubbles form at the inlet of the pump and are moved to the discharge of the pump where they collapse, often taking small pieces of the pump with them.

Effect of Cavitation:

o Loud noise often described as a grinding or “marbles” in the pump,

o Loss of capacity (bubbles are now taking up space where liquid should be present),

o Pitting damage to parts as material is removed by the collapsing bubbles.

Noise is a nuisance and lower flows will slow the process, but pitting damage will ultimately decrease the life of the pump. So, to encounter the cavitation effects and better life of the pump, NPSH is mandatory.

2.4.3 Difference between NPSHA and NPSHR

The net positive suction head required to prevent cavitation is determined through testing by the pump manufacturer and depends upon factors including type of impeller inlet, impeller design, pump flow rate, impeller rotational speed, and the type of liquid being pumped. The manufacturer typically supplies curves of NPSHR as a function of pump flow rate for a particular liquid (usually water) in the vendor manual for the pump.

NPSHA is a function of the system and must be calculated. NPSHA must be greater than NPSHR for the pump system to operate without cavitating. Put it another way, there must be more suction side pressure available than the pump requires.

NPSHA:

The NPSH available to a centrifugal pump combines the effect of atmospheric pressure, water temperature, supply elevation and the dynamics of the suction piping. The following equation illustrates this relationship. The sum of these components represents the total head available at the pump suction.

NPSHA = HA ± HZ − HF + HV − HVP

Term Definition Notes

HA

The absolute pressure on the surface of the liquid in the supply tank

o Typically atmospheric pressure (vented supply tank), but can be different for closed tanks.

o The altitude affects atmospheric pressure.

o Always positive (may be low, but even vacuum vessels are at a positive absolute pressure).

HZ

The vertical distance between the surface of the liquid in the supply tank and the centerline of the pump

o Can be positive when liquid level is above the centerline of the pump (called static head).

o Can be negative when liquid level is below the centerline of the pump (called suction lift).

o Always be sure to use the lowest liquid level allowed in the tank.

HF Friction losses in the suction piping

o Piping and fittings act as a restriction, working against liquid as it flows towards the pump inlet.

21

HV Velocity head at the pump suction port o Often not included as it’s normally quite small.

HVP

Absolute vapor pressure of the liquid at the pumping temperature

o Must be subtracted in the end to make sure that the inlet pressure stays above the vapor pressure.

o Remember, as temperature goes up, so does the vapor pressure.

NPSHR:

The minimum head required at the suction port of the pump to keep the pump from cavitating. By design, each pump has certain characteristics (both physical and hydraulic) which determine the amount of energy needed to force the liquid into the impeller eye, ensure that it remains a liquid (does not cavitate) on its path through the impeller, and cause the amount needed to accomplish this. The nature of the pump eye, the structure of the impeller vanes, vane diameter, speed of operation, and where the pump is operating on its curve are just a few of the factors. The amount of energy needed by a pump is called Net Positive Suction Head Required, or NPSHR.

2.5 Types of Impeller A. Impellers are classified according to the major direction of flow in reference to the axis of

rotation. Thus, centrifugal pumps may have the following:

1. Radial-flow impellers

2. Axial-flow impellers

Fig. 2.5.A.1: Radial-Flow Impeller and Radial Flow Centrifugal Pump

Fig. 2.5.A.2: Axial-Flow Impeller and Axial Flow Centrifugal Pump

22

3. Mixed-flow impellers, which combine radial- and axial-flow principles.

B. Impellers are further classified in one of two categories:

1. Single-suction, with a single inlet on one side

2. Double-suction, with liquid flowing to the impeller symmetrically from both sides

C. The mechanical construction of the impellers gives a still further subdivision into

1. Enclosed, with shrouds or side walls enclosing the waterways

2. Open, with no shrouds

3. Semi-open or semi-enclosed

Fig. 2.5.C: Three types of impeller: (left to right) open, semi-closed, and enclosed (shrouded)

Fig. 2.5.B: Single-Suction and Double-Suction Impellers

Fig. 2.5.A.3: Mixed-Flow Impeller and Mixed Flow Centrifugal Pump

23

Impeller Design

Impellers of pumps are classified based on the number of points that the liquid can enter the impeller and also on the amount of webbing between the impeller blades. Impellers can be broadly classified into two different designs: open and closed. The information below describes these two designs, their respective advantages and disadvantages, and application considerations.

1. Open Design

Open impellers simply consist of a series of vanes attached to a central "hub" designed to be fitted to a shaft. By fitting the vane ends very close to the pump casing, the open impeller is able to prevent large amounts of fluid or gas from recirculating back through the eye. The table below describes other advantages and disadvantages of open impeller designs.

Advantages Disadvantages

1. Easy maintenance – Efficiency can be maintained through frequent vane adjustment. Open design allows for ease of cleaning and clearing of clogs. Pump need not be disassembled for adjustment or maintenance.

1. Impeller-to-casing clearance – tolerances must be manually adjusted to compensate for heat. This adjustment must be done at operating temperature, which may be hazardous.

2. Less expensive to manufacture and inspect due to open design.

2. Use of soft materials – the soft non-sparking materials required are practical in few applications.

3. Vane alteration (cutting and filing to increase capacity) is possible and economical.

2. Closed Design Closed impellers feature two solid plates attached to both sides of the blades. After the impeller media enters the eye and makes its way through the vanes it is drawn into a nozzle and expelled. Because closed impellers have no need for vane/casing tolerance consideration, their efficiency results from the use of wear rings to prevent media from being recirculated back to the eye. The table below lists advantages and disadvantages of enclosed impellers.

Advantages Disadvantages

1. Increased efficiency 1. Maintenance and inspection is impossible to perform without disassembly

2. Suitable for volatile fluids and explosion-prone environments

2. Prone to clogging

3. Compensates for thermal growth 3. Periodic wear ring maintenance is necessary to maintain efficiency

4. More expensive to manufacture

2.6 Pump Casing Pump casing is used to convert a part of velocity energy of the liquid to its pressure energy. It generally covers the impeller which is mounted in the NDE (Non-driving End) side. Pump casings are designed to accommodate a range of impeller diameters which allows impellers to be removed, trimmed, and reinstalled in the same pump casing.

24

2.6.1 Function of Casing

The conversion of velocity head into pressure head occurs in the pump casing. Figure 2.6.1 shows the how velocity head decreases while pressure head increases as the flow moves through the discharge side of the case. The conversion process follows the principle of conservation of energy as stated by Bernoulli’s law. Since total amount of energy must remain constant (assuming not losses or gains), pressure head must increase as velocity head is reduced.

The way to reduce velocity is by increasing the cross-sectional area of the flow through the process of diffusion. Simply put, diffusion occurs when flow area is expanded. The expansion causes a reduction in velocity and an accompanying increase in pressure.

2.6.2 Types of Casing

Casings are generally two types:

1. Volute Casing Volute casings build a higher head. One of the main purposes of a volute casing is to help balance the hydraulic pressure on the shaft of the pump. Running volute-style pumps at a lower capacity than the manufacturer recommends can put lateral stress on the shaft of the pump, increasing wear-and-tear on the seals and bearings, and on the shaft itself.

2. Circular Casing Circular casings are used for low head and high capacity. Circular casings have stationary diffusion vanes surrounding the impeller periphery that convert velocity energy to pressure energy. Conventionally, the diffusers are applied to multi-stage pumps. The suction and discharge nozzles are parts of the casing itself.

2.7 Suction Piping

The important considerations for Suction Piping are:

1. By all means make the pipe as short and straight as possible, particularly if the fluid has suspended solids which may cause plugging or hang-ups;

2. Make sure there is sufficient pressure at the pump suction (this means check the NPSHA against the NPSHR);

3. Eliminate potential for air entrapment in the suction piping

o Maintain adequate levels in supply tanks to eliminate vortices from forming and air

entrapment.

o Avoid high pockets in suction piping, which can trap air.

o Keep all pipe and fitting connections tight in suction vacuum conditions to prevent air

from getting into the pump.

Fig. 2.6.1: Velocity vs. Pressure Head of Flow through Pump

Graph shows the relationship between velocity head and pressure head of flow through the pump. Casing discharge is designed to convert velocity head into pressure head while

preserving the total amount of head.

25

4. Pipe diameter on suction side should be equal or one size larger than pump inlet.

5. Ensure the piping arrangement does not cause strain on the pump casing. Pumps should never support the suction or discharge piping. Any stress on the pump casing by the piping system greatly reduces pump life and performance.

6. Make sure that the stream flow lines are coming in nice and straight at the pump suction. This generally means having 5 to 10D straight pipe ahead of the pump inlet.

7. Avoid the use of filters at the pump inlet if at all possible. If their maintenance is often neglected then the pump will suffer from poor performance and perhaps cavitation.

8. Use a 90° or 45° elbow at the pump inlet pipe end. This will allow almost complete drainage of the tank and is especially useful in the case of fluids that cannot be readily dumped to the sewers. It also provides additional submergence reducing the risk of vortex formation.

9. Use of Eccentric reducer Always use an eccentric reducer at the pump suction when a pipe size transition is required. Put the flat on top when the fluid is coming from below or straight (see next Figure 2.7.3) and the flat on the bottom when the fluid is coming from the top. This will avoid an air pocket at the pump suction and allow air to be evacuated.

Fig. 2.7.2: Elbow on suction intake piping

Fig. 2.7.1: Straight run pipe length on suction intake piping

Fig. 2.7.3: Eccentric reducers at the pump suction

(Source: the Pump handbook published by McGraw-Hill)

26

2.8 Mechanical Seal

2.8.1 Introduction

It is very essential to arrest the leakage of fluid through gaps between the casing and the rotating elements. Generally, gland packing is a useful element for arresting the leakage of fluid. But, in some situations, packing material is not adequate for sealing the shaft. One common alternative method for sealing the shaft is with mechanical seals. Mechanical seals consist of two basic parts, a rotating element attached to the pump shaft and a stationary element attached to the pump casing. Each of these elements has a highly polished sealing surface. The polished faces of the rotating and stationary elements come into contact with each other to form a seal that prevents leakage along the shaft.

2.8.2 Basic Components

Mechanical seals have been developed to address the shortcomings of stuffing box and packing gland assemblies. The main components are shown in Figure 2.8.2.

Mechanical seal designs are quite varied but all based on the same general concept. They do not attempt to seal directly against the rotating shaft as does a packing assembly. Rather, a mechanical seal moves the joint off the shaft and places it between a pair of sealing faces, one which rotates with the shaft and the other which is stationary with the case. The mechanical seal faces are oriented perpendicularly to the shaft axis and held in contact by one or more springs. Thus, mechanical seal designs have been able to eliminate the radial compression required by stuffing box and packing assemblies.

While the amount of leakage through a mechanical seal is generally less than through packing, some is still required for lubrication. The need for lubrication exists because the rotating-to-stationary seal faces would quickly be destroyed if allowed to run dry. Mechanical seal designs employ various means of lubrication. The lubricating fluid can be gas or liquid.

2.8.3 Types of Mechanical Seal & Applications

A. Classification by design:

A1. Spring design A1.1. Single Spring, A1.2. Multiple Spring.

A2. Balancing A2.1. Unbalanced, A2.2. Balanced.

B. Classification by arrangement:

B1. Single Seal

Fig. 2.8.2: Simplified illustration which shows the general elements comprising mechanical seals.

Dynamic seal occurs between the rotating and fixed seal faces. Spring maintains contact pressure between the faces. Variations in design due to type of lubricating fluid and

contacting/non-contacting are not shown.

27

B1.1. Inside, B1.2. Outside

B2. Double Seal B2.1. Back to Back, B2.2. Tandem

2.8.4 Advantages and Disadvantages of Mechanical Seal

Advantages:

o Reduced friction and hence power losses.

o Elimination of wear on Shaft or Shaft sleeve.

o Zero or controlled leakage over a long period.

o Relatively insensitive to shaft deflection or end play.

o Can be used for hazardous & toxic fluids.

o Freedom from periodic Maintenance.

Disadvantages:

o High initial cost.

o Requires services of expert personnel.

o Calls for employment of good flushing methods.

2.8.5 Different Types of Plans Mechanical Seal Piping Plans most used in IOP

o Plan 11, Plan 13 & Plan 52

A. Plan-11:

o Seal flush from pump discharge through orifice.

o Default single seal flush plan.

Why it is used?

1. Seal chamber heat removal.

2. Seal chamber venting on horizontal pumps.

3. Increase seal chamber pressure and fluid vapor margin.

Applications:

General applications with clean, non-polymerizing fluids.

Fig. 2.8.5.A: Plan – 11

28

Preventative Maintenance (Source: flowserve.com)

o Use an orifice with a minimum 3 mm (1/8 inch) diameter.

o Calculate flow rates to size orifice for adequate seal chamber flow.

o Increase boiling point margin with proper orifice and throat bushing sizing.

o Flush should be directed over seal faces with piping at 12 O’clock position.

o Typical failure mode is a clogged orifice - check temperatures at pipe ends.

B. Plan-13:

o Recirculation from seal chamber to pump suction through orifice.

o Standard flush plan on vertical pumps.

Why it is used?

1. Continuous seal chamber venting on vertical pumps.

2. Seal chamber heat removal.

Applications:

o Vertical pumps.

o Where Seal chamber pressure is greater than suction pressure.

o Moderate temperature fluids with moderate solids.

o Non-polymerizing fluids.

Preventative Maintenance (Source: flowserve.com)

o Vent piping loop prior to starting vertical pumps.

o Use an orifice with a minimum 3 mm (1/8 inch) diameter.

o Calculate flow rates to size orifice for adequate seal chamber flow.

o Reduce seal chamber pressure with proper orifice and throat bushing sizing.

o Typical failure mode is a clogged orifice - check temperatures at pipe ends.

C. Plan-52:

o Unpressurized buffer fluid circulation through reservoir.

o Fluid is circulated by a pumping ring in the dual seal assembly.

Fig. 2.8.5.B: Plan – 13

29

Why it is used?

1. Outboard seal acts as a safety backup to the primary seal.

2. Zero to very low process emissions.

3. No process contamination is allowed.

Applications:

o Used with dual unpressurized seals.

o High vapor pressure fluids, light hydrocarbons.

o Hazardous/toxic fluids.

o Heat transfer fluids.

Preventative Maintenance (Source: flowserve.com)

o Piping loop must self-vent to vapor recovery/flare system near atmospheric pressure.

o Process vapor pressure is generally greater than reservoir pressure.

o Buffer fluid must be compatible with process leakage.

o Primary seal leakage is indicated by increased vent pressure.

o Reservoir level indicator shows outboard seal leakage.

2.9 Performance Curve of Centrifugal Pumps

Generally, manufactures provide the

head-discharge curve which is called

the characteristics curve of the

pump. The highest point of the

efficiency curve is called Best

Efficiency Point (BEP). The

operators have the system curve

depending upon the usage of the

pump. The intersecting point of the

H-Q curve and the system curve is

called operating point as shown in

the diagram.

Fig. 2.8.5.C: Plan – 52

30

2.10 Pumps in IOP

Centrifugal pumps are mostly used in IOP. There are also application of reciprocating pumps in IOP in specified places. Here some of the pumps are described in details.

Pump areas in IOP The pump areas in IOP are: 22, 23, 25, 33, 41, 42, 43, 45, 46, and 47. Among these areas, four pumps are selected for detailed description.

1. 41-P-10B:

o Service: C3/C4 Mixed LPG/Propylene Unloading Pump.

o Pump Type: Vertical Barrel type Multi Stage Centrifugal Pump

o Capacity (m3/hr.): 15 (Minimum), 45 (Normal), 50 (Maximum), 60 (at B.E.P.)

o Coupling Type: Metaflex Coupling.

o Mechanical Seal Type: Durametallic, Tandem Seal.

o Plans installed:

1. Plan-13: Recirculation from Mechanical seal through orifice to pump suction.

2. Plan-52: Circulation to Outboard seal through container.

3. Plan-61: Vent/Inlet and drain plugged.

o Differential Head (m): 80 (Butane), 90 (Propane), 85 (Propylene)

o Casing Mounting: Vertical Barrel

o Performance:

31

o Diagram:

2. 42-P-002 A/B/C:

o Service: HP Ethylene Pump.

o Pump Type: Vertical Barrel type Multi Stage Centrifugal Pump

o Capacity (m3/hr.): 80 (at B.E.P.)

o Coupling Type: Metaflex Coupling (Triveni Flexibox TSKS-0060-0037-1800)

o Mechanical Seal Type: Tandem Type (Make: Sealol)

o Plans installed:

1. Plan-13: Recirculation from Mechanical seal through orifice to pump suction.

2. Plan-52: Circulation to Outboard seal through container.

o Maximum Head Rated (m): 615

o Speed: 2960 rpm

o Casing Mounting: Vertical Barrel

o No. of stages: 14

32

o Performance: Efficiency 70%

33

o Diagram:

34

3. 23-P-009 A/B:

o Service: ACF Backwash Water Pump.

o Pump Type: Single volute foot casing type Centrifugal Pump

o Capacity (m3/hr.): 330 (at B.E.P.)

o Coupling Type: Flexible Spacer.

o Packing Type: Gland Packing.

o Maximum Head Rated (m): 40

o Speed (rpm) : 1470

o Casing Mounting: Foot Casing

35

o Performance: Efficiency – 77.50%

36

o Diagram:

4. 25-P-002G

o Service: Cooling Water Circulation pump.

o Pump Type: Double Suction type Horizontal Centrifugal Pump (Double Volute, simple

supported)

o Capacity (m3/hr.): 4500 (at B.E.P.)

o Coupling Type: Flexi-metallic Spacer.

o Packing Type: Gland Packing.

o Maximum Head Rated (m): 72

o Speed (rpm) : 992

o Casing Mounting: Foot Casing

37

o Performance: Efficiency – 93.0%

38

o Diagram:

****

39

REFERENCES A Report on Pumps in IOP

R E S O U R C E S

1. Pump Handbook of McGraw-Hill Edited by

Igor J. Karassik, Joseph P. Messina, Paul

Cooper, and Charles C. Heald.

2. Centrifugal Pumps: Overview of Design,

Operation and Malfunctions by D. Craig

Sever and Charles T. Hatch (Bently Nevada

Corporation).

3. Enggcyclopedia (Industrial Wiki:

https://www.myodesie.com).

4. Pumps & Systems

(www.pumpsandsystems.com).

5. Engineering Toolbox

(http://www.engineeringtoolbox.com).

6. PowerPoint presentation of IOP DETAILS.

7. IOP Pumps Manual Drawings of area: 41, 42,

23 & 25.

8. IOP Tanks Manual Drawings (41-T-001

A/B/C/D).

Summer Report

Haldia Petrochemicals Limited