Page 23 - Compression Machinery for Oil and Gas

Chapter 2

Equipment Overview

†
Benjamin White*, Terry Kreuz and George Talabisco ‡
* †
Southwest Research Institute, San Antonio, TX, United States, National Fuel Gas, Williamsville,
‡
NY, United States, Dresser-Rand, Olean, NY, United States

Types of Compression Equipment

Compression equipment is available in a wide range of types and sizes for use in
many different industry applications. Compressors are generally divided into
two main categories: positive displacement compressors and dynamic com-
pressors. Positive displacement compressors typically include reciprocating
compressors (single acting, double acting, hyper), rotary compressors (screw,
scroll, vane), and diaphragm compressors. Dynamic compressors include cen-
trifugal compressors and axial compressors. A summary of compressor types is
shown in Fig. 2.1.
Each compressor type is usually best suited for a particular range of flow
rates, pressures, and fluid types. However, there is also a lot of overlap in some
applications. For industrial oil and gas applications, the two most common com-
pressor types are reciprocating and centrifugal compressors. In very broad
terms, reciprocating compressors are usually best for applications with low-
to-medium flow and low-to-high pressures. Reciprocating compressors also
tend to be very flexible in terms of varying flow rates, gas compositions, and
fluid densities. Multistage reciprocating compressors can generate very high-
pressure ratios across a single machine. Centrifugal compressors are usually
best for applications with medium-to-high flow and low-to-medium pressures.
Centrifugal compressors typically have smaller physical footprints for a given
power rating, lower maintenance costs, and longer run times between mainte-
nance intervals. Centrifugal compressors also have lower unbalanced forces and
are typically much less susceptible to pulsation and vibration-related issues.
However, as discussed later in this chapter, there are also many other factors
to consider when selecting the ideal compressor for a particular application.
Fig. 2.2 shows typical coverage ranges for various types of compressors. These
range from axial compressors which can produce very high flow rates with

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