Page 194 - Compression Machinery for Oil and Gas

Reciprocating Compressors Chapter 5 183

l ISO 13707:2000 “Petroleum and natural gas industries—Reciprocating
compressors,” published in 2000. It is based on API 618 Fourth Edition pub-
lished June 1995. API Standard 618 Sixth Edition will not be published as an
ANSI/ISO standard as was the Fifth Edition. I am not aware of what plans
ISO may have for a new edition.
l ISO 13631:2002 “Petroleum and natural gas industries—Packaged recipro-
cating gas compressors,” published in 2002. It is based on API Standard 11P
Second Edition published November 1989. API Standard 618 Sixth Edition
will not be published as an ANSI/ISO standard as was the Fifth Edition. I am
not aware of what plans ISO may have for a new edition.
l Gas Machinery Research Council (GMRC), division of the Southern Gas
Association “Guideline for High-Speed Reciprocating Compressor Pack-
ages for Natural Gas Transmission & Storage Applications,” published
2016. This is not a standard or specification as GMRC does not have any
authority to publish a nationally recognized standard. This guideline is
intended to provide guidance in packaging oil and gas industry reciprocating
compressors 2000hp and larger.
l GMRC “High-Speed Compressor Package Guideline for Field Gas Appli-
cations,” published 2017. This is not a standard or specification as GMRC
does not have any authority to publish a nationally recognized standard. This
guideline is intended to provide guidance in packaging oil and gas industry
reciprocating compressors 2000hp and smaller.

Performance

Cylinder Swept Volume Process Overview
A reciprocating compressor is a positive displacement machine in that a volume
of gas is drawn into a compressor cylinder’s compression chamber where it is
trapped, compressed, and pushed out. The P-V diagram is a plot of the pressure
of the gas vs. the volume of the gas trapped in the compression chamber. In
Fig. 5.2, P S , suction pressure, represents the pressure of the gas at the inlet
to the compressor cylinder. P D , discharge pressure, represents the pressure of
the gas at the outlet from the compressor cylinder. V 1 represents the maximum
volume of gas trapped in the compression chamber and V 3 the minimum. The
difference between V 1 and V 3 is known as piston displacement, or how much
volume is displaced in one stroke length of the piston:
Piston Displacement ¼ V 1 V 3
Referring to Fig. 5.2, the P-V diagram is made up of four basic segments or
events, 1-2, 2-2A-3, 3-4, and 4-4A-1, and each is explained. Position 1 has the
maximum volume (V 1 ) of gas trapped in the compression chamber and that gas
is at suction pressure and temperature. At Position 1 all of the compressor valves
are closed and the piston is at rest. All of the compressor valves are simple