Page 26 - Compression Machinery for Oil and Gas

16 SECTION I Fundamentals of Compression

Midstream
1. Pipeline transmission compression is the transportation of natural gas from
the source (wells) to the distribution system. This is a typical application for
centrifugal and reciprocating compression systems.
2. Gas storage injection/withdrawal: old well formations are sometimes used
as peaking storage locations for natural gas transmission and distribution
systems. They are used to provide additional capacity at various locations
where peak demand can exceed capability of existing pipelines to provide
the necessary product at the required pressure levels. Typical compression
equipment consists of both reciprocating and centrifugal compressors that
are used to inject the gas into the storage formation and to boost the pressure
during removal to meet pipeline pressure requirements.
3. Natural gas processing: this application removes unwanted components
from raw and untreated natural gas to make it suitable to be classified as
pipeline quality gas. Centrifugal and reciprocating compressors can be used
in this application.

Downstream

1. Refinery/process applications: compressors constitute an important part of
the mechanical equipment in oil and gas refineries and petrochemical
plants. Compressors are used for different applications in the main and aux-
iliary process cycles:
a. Recycling compressors designed to provide a steady flow of process gas
through a closed circuit in order to maintain the required process param-
etersin theplant units(e.g., hydrogen-rich gas recycling ina hydrotreater)
b. Feed compressors supplying process gas to reactor
c. Booster compressors
d. Sales gas compressors (e.g., methane)
e. Electrically driven reciprocating and centrifugal compressors are most
commonly used in oil and gas refining facilities
2. Ethylene/Low-density polyethylene (LDPE): due to the extremely high dis-
charge pressures required in these applications, large horizontal opposed
reciprocating compressors for the highest discharge pressures are required
(aka hyper compressors). This type of compressor is used in the LDPE pro-
duction process (low-density polyethylene) as a secondary compressor in
combination with a process gas compressor used as a booster/primary
compressor.
3. CNG (compressed natural gas) is a fuel for vehicles or other commercial
applications made by compressing natural gas or biogas to less than 1%
of its uncompressed volume. Compressors are used to boost the pressure
of the gas and they are the primary equipment of a CNG refueling station