working guide to pumps and pumping stations calculations and simulations pdf

Preface

This book is about the application of pumps and pumping stations used in pipelines
transporting liquids. It is designed to be a working guide for engineers and technicians dealing with centrifugal pumps in the water, petroleum, oil, chemical, and
process industries.

The reader will be introduced to the basic theory of pumps and
how pumps are applied to practical situations using examples of simulations, without extensive mathematical analysis. In most cases, the theory is explained and followed by solved example problems in both U.S.

Customary System (English) and SI
(metric) units.

Additional practice problems are provided in each chapter as further
exercise.
The book consists of nine chapters and nine appendices.

 chapter 1

introduces the reader to the various types of pumps used in the industry, the properties of
liquids, performance curves, and the Bernoulli’s equation.

 chapter 2

discusses the performance of centrifugal pumps in more detail, including variation with impeller speed and diameter. The concept of specific speed is introduced and power calculations explained.

Chapter 3

reviews the effect of liquid specific gravity and viscosity
on pump performance and how the Hydraulic Institute Method can be used to correct the pump performance for high viscosity liquids.

The temperature rise of a liquid
when it is pumped and pump operation with the discharge valve closed are discussed.
Chapter 4

introduces the various methods of calculating pressure loss due to friction in piping systems. The Darcy equation, friction factor, the Moody diagram,
and the use of the two popular equations for pressure drop (Hazen-Williams and
Colebrook-White) are reviewed, and several examples illustrating the method of
calculation are solved. Minor losses in valves and fittings, and equivalent lengths
of pipes in series and parallel, are explained using example problems.

Chapter 5

introduces pipe system head curves and their development, as well as how they are
used with the pump head curves to define the operating point for a specific pump
and pipeline combination.

Chapter 6

explains Affinity Laws for centrifugal pumps
and how the pump performance is affected by variation in pump impeller diameter
or speed. The method of determining the impeller size or speed required to achieve
a specific operating point is explained using examples.

Introduction

The function of a pump is to increase the pressure of a liquid for the purpose of
transporting the liquid from one point to another point through a piping system or
for use in a process environment. In most cases, the pressure is created by the conversion of the kinetic energy of the liquid into pressure energy.

Pressure is measured
in lb/in2 (psi) in the U.S. Customary System (USCS) of units and in kPa or bar in
the Systeme International (SI) system of units.

Other units for pressure will be discussed in the subsequent sections of this book. Considering the transportation of a
liquid in a pipeline, the pressure generated by a pump at the origin A of the pipeline
must be sufficient to overcome the frictional resistance between the liquid and the
interior of the pipe along the entire length of the pipe to the terminus B.

In addition,

Working Guide to Pumps and Pumping Stations
the pressure must also be sufficient to overcome any elevation difference between A
and B. Finally, there must be residual pressure in the liquid as it reaches terminus B
if it is to perform some useful function at the end.
If the elevation of B is lower than that of A, there is an elevation advantage where
the pump is located that will result in a reduction in the pressure that must be generated by the pump. Conversely, if the elevation of B is higher than that of A, the
pump has to work harder to produce the additional pressure to overcome the elevation difference. 

mostly centrifugal pumps for their pumping systems, our analysis throughout this
book will be geared toward centrifugal pumps.
Centrifugal pumps may be classified into the following three main categories:
Radial flow pumps
W Axial flow pumps
Mixed flow pumps
Radial flow pumps develop pressure by moving the pumped liquid radially with
respect to the pump shaft.

They are used for low flow and high head applications.
Axial flow or propeller pumps develop pressure due to the axial movement of the
pumped liquid and are used for high flow and low head applications. The mixed
flow pumps are a combination of the radial and axial types, and they fall between
these two types.

The specific speed of a pump, discussed in Chapter 2, is used to
classify the type of centrifugal pumps. Radial flow pumps have low specific speeds
(less than 2000), while axial flow pumps have high specific speeds (greater than
8000). Mixed flow pumps fall in between.

Liquid Properties
Liquid properties affect the performance of a pump. In this section, some of the
important and basic physical properties of liquids that will have a direct bearing on
pump performance are reviewed. The three most important liquid properties when
dealing with centrifugal pumps are specific gravity, viscosity, and vapor pressure.

SPECIFIC GRAVITY
Specific gravity is a relative measure of the density of a liquid compared to water at the
same temperature and pressure. The density is a measure of how heavy a liquid is compared to its volume, or the space it occupies.

Thus, we may refer to density in terms
of mss per unit volume. A related term is spec@ weight, or weight density, which is
simply the weight per unit volume. If the mass of a certain volume of a liquid is known,
dividing the mass by its volume gives the density.

You can also obtain the weight density by taking the weight of a certain amount of liquid and dividing it by the volume.
Generally, we tend to use the terms mass and weight interchangeably.