Contents

Cover

Title page

Copyright page

Dedication

Acknowledgements

Preface

Chapter 1: Introduction to Gases

1.1 Ideal Gases
1.2 Properties of Gases
1.3 Temperature
1.4 Pressure
1.5 Gas Laws
1.6 Gas Mixtures
1.7 Molecular Weight of a Gas Mixture
1.8 Gas Density
1.9 Density of Mixtures
1.10 Heat of Compression

Chapter 2: Commonly Used Compressor Flow Terms

2.1 Ideal Gas Law
2.2 Visualizing Gas Flow
2.3 Compressibility Factor (Z)
2.4 Sizing Compressors

Chapter 3: Compression Processes

3.1 Adiabatic Compression
3.2 Polytropic Compression

Chapter 4: What Role the Compression Ratio Plays in Compressor Design and Selection

4.1 Compression Ratio versus Discharge Temperature
4.2 Design Temperature Margin

Chapter 5: An Introduction to Compressor Operations

5.1 Compression Basics
5.2 Defining Gas Flow
5.3 Compressor Types
5.4 Multistaging
5.5 Key Reliability Indicators

Chapter 6: Centrifugal Compressors

6.1 Centrifugal Compressor Piping Arrangements
6.2 Start-Up Configuration
6.3 Centrifugal Compressor Horsepower
6.4 Troubleshooting Tips
6.5 Centrifugal Compressor Start-Ups
6.6 Centrifugal Compressor Checklist

Chapter 7: How Process Changes Affect Centrifugal Compressor Performance

7.1 Baseball Pitcher Analogy
7.2 How Gas Density Affects Horsepower
7.3 Theory versus Practice

Chapter 8: How to Read a Centrifugal Compressor Performance Map

8.1 The Anatomy of a Compressor Map
8.2 Design Conditions

Chapter 9: Keeping Your Centrifugal Compressor Out of Harm’s Way

9.1 Compressor Operating Limits
9.2 Compressor Flow Limits
9.3 Critical Speeds
9.4 Horsepower Limits
9.5 Temperatures

Chapter 10: Troubleshooting Centrifugal Compressors in Process Services

10.1 The Field Troubleshooting Process—Step by Step
10.2 The “Hourglass” Approach to Troubleshooting
10.3 Thinking and Acting Globally
10.4 Troubleshooting Matrix and Table
10.5 Centrifugal Compressor Troubleshooting Example

Chapter 11: Reciprocating Compressors

11.1 Reciprocating Compressor Installations
11.2 Reciprocating Compressor Start-Ups
11.3 Reciprocating Compressor Checklist
11.4 Criticality

Chapter 12: Troubleshooting Reciprocating Compressors in Process Services

12.1 The Field Troubleshooting Process—Step by Step

Chapter 13: Screw Compressors

13.1 Oil Injected Screw Compressors
13.2 Screw Compressor Modulation
13.3 Pressure Pulsation Issues
13.4 Troubleshooting Screw Compressors

Chapter 14: Compressor Start-Up Procedures

14.1 Compressor Start-Up Risks
14.2 Generic Start-Up Procedure
14.3 Centrifugal Compressor Start-Ups
14.4 Reciprocating Compressor Start-Ups
14.5 Screw Compressor Start-Ups

Chapter 15: Compressor Trains: Drivers, Speed Modifiers, and Driven Machines

15.1 Driven Process Machines
15.2 Gas Turbines
15.3 Useful Gearbox Facts
15.4 Combination Machines

Chapter 16: Compressor Components

16.1 Bearing Types
16.2 Rolling Element Bearings
16.3 Plain Bearings
16.4 Compressor Bearings
16.5 Modeling Fluid Film Bearings
16.6 Thrust Loads
16.7 Kingsbury Thrust Bearing
16.8 Compressor Seals
16.9 Seal Oil System
16.10 Dry Gas Seals
16.11 Seal Gas Quality and Control
16.12 Reciprocating Compressors – Packing

Chapter 17: The Importance of Lubrication

17.1 Lubrication Regimes
17.2 Lubricating Oils
17.3 Compressor Lubricating Oil Systems
17.4 Oil Foaming

Chapter 18: Inspection Ideas for Operators and Field Personnel

18.1 Equipment Field Inspections
18.2 Tools Available to Quantify What You Have Detected
18.3 Visual Inspection Methods
18.4 IR Camera
18.5 Inspection Methods Using Vibration and Temperature Measurement Equipment
18.6 Generic Monitoring Guidelines

Chapter 19: Addressing Reciprocating Compressor Piping Vibration Problems: Design Ideas, Field Audit Tips, and Proven Solutions

19.1 Piping Restraints
19.2 Pipe Clamping Systems
19.3 Guidelines
19.4 Piping Assessment Steps
19.5 Attaching Pipe Clamps to Structural Members

Chapter 20: Collecting and Assessing Piping Vibration

20.1 Piping Analysis Steps
20.2 Piping Vibration Examples

Appendix A: Practice Problems Related to Chapters 1 Through 4 Topics

Appendix B: Glossary of Compressor Technology Terms

Index

End User License Agreement

List of Illustrations

Chapter 1

Figure 1.1 Gas atoms or molecules are constantly moving and colliding with one another.
Figure 1.2 As gas is compressed, the gas molecules get closer together.
Figure 1.3 Oxygen, nitrogen, and carbon monoxide are examples of diatomic molecules. Carbon...
Figure 1.4 Starting with a piston having a given pressure and volume (far right piston)...
Figure 1.5 Dalton’s law of partial pressures.
Figure 1.6 Molecular structure of methane, ethane, and propane.
Figure 1.7 Air fin cooler, which is located on the far right of the skid, provides interstage...
Figure 1.8 Schematic of a two-stage reciprocating compressor with an intercooler between...

Chapter 2

Figure 2.1 Centrifugal Compressor in a Petrochemical Facility.
Figure 2.2 Hypothetical compressor piping system.
Figure 2.3 The three main categories of gas compressors: Screw, Reciprocating, and Centrifugal...

Chapter 3

Figure 3.1 The ideal gas laws cannot be used to predict compressor performance.
Figure 3.2 Reciprocating compressors’ performance can be approximated using the...
Figure 3.3 Pressure versus stroke diagram for a reciprocating compressor.
Figure 3.4 Centrifugal compressor performance can be approximated using polytropic formula.

Chapter 4

Figure 4.1 Skid mounted reciprocating compressor.
Figure 4.2 How the theoretical discharge temperature is affected by the compressor discharge...

Chapter 5

Figure 5.1 During the gas compression process, a volume of gas is decreased in order to...
Figure 5.2 Compressor schematic.
Figure 5.3 Basic compressor designs.
Figure 5.4 Cross section of a reciprocating compressor.
Figure 5.5 Rotary screw compressor.
Figure 5.6 Multistage centrifugal compressor.

Chapter 6

Figure 6.1 Centrifugal compressor cutaway.
Figure 6.2 Compressor rotor inside of a split casing. Notice that every impeller exit...
Figure 6.3 Labyrinth seals are used to minimize gas leakage between stages.
Figure 6.4 Cross section of centrifugal compressor.
Figure 6.5 Centrifugal Compressor Performance Curve. There is a performance curve for...
Figure 6.6 Typical single-stage compressor piping arrangement.

Chapter 7

Figure 7.1 Pitcher throws a baseball towards the batter’s box.
Figure 7.2 Cross section of a centrifugal compressor showing the impeller and diffusers.
Figure 7.3 Technically, the creation of gas pressure inside a compressor is best explained...

Chapter 8

Figure 8.1 A cutaway of a centrifugal compressor showing the rotor and diffusers.
Figure 8.2 Generalized high-pressure compressor map.
Figure 8.3 Typical high-pressure compressor map.
Figure 8.4 Typical centrifugal compressor surge control system.

Chapter 9

Figure 9.1 Multistage centrifugal compressor rotor.
Figure 9.2 Centrifugal compressor operating limits. This compressor curve represents...
Figure 9.3 Typical Centrifugal Compressor Surge Control System.
Figure 9.4 Here is a typical predicted forced response plot. The upper plot is the 1x...

Chapter 10

Figure 10.1 Hourglass approach. Funnel—pertinent data collection. Focus—analysis...

Chapter 11

Figure 11.1 Reciprocating compressor cylinder cross section.
Figure 11.2 A crankshaft is a subcomponent of a reciprocating compressor that converts...
Figure 11.3 The upper plot, comprised of points A, B, C, D, shows how the pressure changes...
Figure 11.4 There are many different types of reciprocating compressor valves. The one shown...
Figure 11.5 Valve unloaders can be used to partially unload or fully unload a reciprocating...
Figure 11.6 A volume unloader can either increase the volumetric efficiency (VE) of a...
Figure 11.7 Finger type unloaders hold a valve open to prevent the valve from working normally.
Figure 11.8 Multistage reciprocating compressor piping arrangement.

Chapter 13

Figure 13.1 Typical screw compressor rotors.
Figure 13.2 Flow and pressure range comparison of screw, reciprocating, and centrifugal...
Figure 13.3 Screw compressor compression process.
Figure 13.4 Types of screw compressors.
Figure 13.5 Oil-flooded screw compressor.
Figure 13.6 Oil-flooded screw compressor package.
Figure 13.7 An internal slide valve is used to modulate screw compressor flow.
Figure 13.8 Combination silencer.

Chapter 15

Figure 15.1 An electric motor directly coupled to a reciprocating compressor.
Figure 15.2 AC induction motor.
Figure 15.3 Cross-section of single-stage turbine and governor system.
Figure 15.4 Industrial gas turbine: The air compressor is on the right and the combustion...
Figure 15.5 Reciprocating compressor driven by a natural gas engine.
Figure 15.6 Gearbox.
Figure 15.7 Turboexpander unit removed from service. The compressor end is on the left side...

Chapter 16

Figure 16.1 Types of bearings.
Figure 16.2 Different types of rolling element bearings.
Figure 16.3 Cutaway of a plain (journal) bearing and shaft.
Figure 16.4 Tilting pad bearing.
Figure 16.5 Here are some of the many fluid film bearings available to turbomachinery...
Figure 16.6 Balance piston or drum.
Figure 16.7 Kingsbury thrust bearing.
Figure 16.8 Labyrinth seal.
Figure 16.9 Oil bushing seal.
Figure 16.10 To prevent process gas from leaking, the seal oil pressure must always be maintained...
Figure 16.11 Compressor face seal.
Figure 16.12 Dry gas compressor seal.
Figure 16.13 Typical reciprocating compressor packing box.

Chapter 17

Figure 17.1 Boundary lubrication.
Figure 17.2 Full fluid lubrication.
Figure 17.3 The rotation of a journal within a journal bearing creates a wedge-shaped oil...
Figure 17.4 Typical compressor lube oil system.
Figure 17.5 How oil appearance can change as it becomes contaminated. Remember to look for...
Figure 17.6 Oil Foaming.

Chapter 18

Figure 18.1 Operators inspecting an electric motor in the field.
Figure 18.2 Over-lubricated bearing.
Figure 18.3 Infrared temperature gun.
Figure 18.4 IR camera picture.
Figure 18.5 Pocket strobe light.
Figure 18.6 Technician using vibration meter with an accelerometer.
Figure 18.7 Vibration trend example.
Figure 18.8 Temperature trend.

Chapter 19

Figure 19.1 Operators must remain vigilant around reciprocating compressors and their associated...
Figure 19.2 If fundamental (1x) or harmonics (2x, 3x, etc.) pulsation frequencies acting on...
Figure 19.3 (a) Pipe clamp with liner material on the clamp ID and on pipe wedges. (b) Properly...
Figure 19.4 Some typical small-bore piping designs that can result in excessive vibration...
Figure 19.5 PSV support off a main piping.
Figure 19.6 Pipe clamp with integral spacers using cap screws.
Figure 19.7 A properly installed pipe clamp bolted to a concrete pier. Notice that there is...
Figure 19.8 Correctly installed pipe clamps on concrete footing.
Figure 19.9 An incorrectly installed pipe clamp. Notice that with the clamp bottomed out...
Figure 19.10 There is insufficient clamping force on this clamp due to the loss of wedge...

Chapter 20

Figure 20.1 Piping assessment chart (Based on Engineering Dynamics Inc. (EDI) guidelines).
Figure 20.2 Mag-mounted tri-axial accelerometer on a pipe.
Figure 20.3 Mag-mounted tri-axial accelerometer on a valve.
Figure 20.4 Waterfall Display of Piping Vibration.

Appendix A

Figure A.1 Gas compressed with a piston.
Figure A.2 How gas volume varies with pressure.
Figure A.3 The molecular structure of propane.
Figure A.4 Reciprocating compressor spillback line and cooler schematic.
Figure A.5 Two stage reciprocating compressor installation.
Figure A.6 Electric motor driven reciprocating compressor.
Figure A.7 Centrifugal barrel compressor.

List of Tables

Chapter 1

Table 1.1 Composition of methane.
Table 1.2 Molecular weights of some common hydrocarbons. Compare the chemical formulas in...
Table 1.3 Calculating the molecular weight of a gas mixture.

Chapter 2

Table 2.1 Below Summarizes the Change in Volumetric Flow Rates at These Conditions.
Table 2.2 Compressor Coverage Table (English Units) ⁽¹⁾.
Table 2.3 Compressor Coverage Table (Metric Units).

Chapter 3

Table 3.1 Below contains K values for some common gases.

Chapter 4

Table 4.1 Below contains K values for some common gases.
Table 4.2 The Effect of discharge pressure on the theoretical discharge temperature.

Chapter 5

Table 5.1 Compression ratio ranges.

Chapter 7

Table 7.1 The Weights and weight ratios (ball weight/foam ball weight) of various types...
Table 7.2 How deviations from design conditions affect centrifugal compressor performance.

Chapter 10

Table 10.1 Key troubleshooting questions.
Table 10.1a Centrifugal compressor troubleshooting matrix example.
Table 10.1b Centrifugal compressor troubleshooting matrix.
Table 10.1c Centrifugal compressor troubleshooting tips.

Chapter 11

Table 11.1 How process conditions affect reciprocating compressor performance. Note: The...

Chapter 12

Table 12.1 Basic troubleshooting questions.
Table 12.2a Reciprocating compressor troubleshooting matrix.
Table 12.2b Reciprocating compressor troubleshooting matrix.
Table 12.2c Reciprocating compressor troubleshooting tips.

Chapter 13

Table 13.1 How process conditions affect screw compressor performance. Note: The results...

Chapter 14

Table 14.1 Recommended Compressor Inspection.

Chapter 15

Table 15.1 Common Types of Process Machinery Elements.

Appendix A

Table A.1 Composition of methane.
Table A.2
Table A.3 Compressor Coverage Table (English Units) ⁽¹⁾.

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Library of Congress Cataloging-in-Publication Data

ISBN 978-1-119-58061-4

Preface

Gas compressors are installed in most large processing facilities. They are designed to transport gases between different locations in processing units by compressing them from a lower pressure to a higher one using some type of driver, such as an electric motor, a steam turbine, a gas turbine, etc. The process of gas compression requires that compressors be designed to handle high gas pressures, high operating temperatures, high rotational speeds, and the high component stress levels. Through their gradual technological evolution, compressors have become highly reliable and safe machines, when properly maintained and operated as intended by their designers.

Gas compressors tend to be the largest, most costly, and most critical machines employed in chemical and gas transfer processes. The most common types of compressors are centrifugal compressors, reciprocating compressors, and screw compressors. Since they tend to have the greatest effect on the reliability of processes they power, compressors typically receive the most scrutiny of all the machinery among the general population of processing equipment.

Today, there appears to be a need in industry for a review of the best in class operating methods and procedures for compressors. As the previous generation of operators retire or move on, much of the knowledge that was gained over the past years has been forgotten or lost. The attrition of experience we have all experienced in recent years has resulted in the recurrence of reliability problems that have already been solved. To prevent unwanted compressor failures from occurring, operators must be taught how the equipment should operate and how each is different from one another.

The ultimate purpose of this book is to teach those who work in process settings more about gas compressors, so they can start them up and operate them correctly and monitor them with more confidence. Some may regard compressor technology as too broad and complex a topic for operating personnel to fully understand, but I have tried to address this concern by distilling this vast body of knowledge into some key, easy to understand lessons for the reader to study at his or her own pace. My hope is that learning more about how compressors work and the factors that are key to their reliability, compressor operators can keep them running longer and more reliably.

The main goals of this book are to:

Explain important theories and concepts about gases and compression processes with a minimum of mathematics
Identify key compressor components and explain how they affect reliability
Explain how the different types of compressors function
Explain key operating factors that affect reliability
Introduce the reader to basic troubleshooting methodologies
Introduce operators to proven field inspection techniques

I hope that readers find this book useful as they progress through their careers. I recommend that occasionally readers review the book’s content to refresh their knowledge of compressors.

Always keep learning and questioning your assumptions and paradigms. I think the following quotation explains why it’s important to change your point of view from time to time:

“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won’t come in.”

— Isaac Asimov

Robert X. Perez
Spring, 2019