Page 31 - Compression Machinery for Oil and Gas

Equipment Overview Chapter 2 21

The operation of compression equipment will typically generate emissions
to the air during the combustion process (depending on the type of driver) and
will typically be subject to various emission regulations, such as the Clean Air
Act. Planned and unplanned emissions tests are often conducted on a regular
basis by local regulatory representatives.
Intentional or unintentional discharges of the process gas from the system
should also be considered (leaks, blowdowns, etc.). Methane, the primary com-
ponent in natural gas, is a known greenhouse gas. In addition, CO 2 and nitrous
oxides are natural by-products of the combustion process.
The common sources of air emissions include:

1. combustion gases,
2. boilers,
3. release of gas,
4. fugitive omissions,
5. gas vents,
6. gas leaks,
7. storage tanks,
8. reciprocating engines,
9. heaters,
10. dehydration,
11. blowdown,
12. crankcase vents of reciprocating compressors,
13. packing case vents for reciprocating compressors,
14. cooling system vents, and
15. other miscellaneous factors.
Given the proximity of many compressor stations to residential neighbors, noise
generated by the compression equipment can be a factor, particularly when
ambient noise conditions are low, such as at night in rural settings. Sources
of noise could include the turbine or engine air intakes and exhaust systems,
blowdown systems, gas coolers, auxiliary air compressors or generators, etc.
Pulsation and vibration in the piping can also be similar irritant to nearby res-
idential neighbors. Valves especially antisurge-recycle valves can be a source of
noise and require noise attenuation trim along with acoustic insulation to
minimize noise.
A maximum noise limit of 55dB(A) is often required by FERC (Federal
Energy Regulatory Commission), which can difficult to meet in some installa-
tions. Noise control is usually achieved by employing a combination of tech-
niques including the installation of engine exhaust and inlet silencers, noise
insulation on the piping, acoustically insulated building and enclosures, etc.
A comprehensive noise assessment should be conducted at the design phase.
Compressor stations are required to be designed, constructed and operated in
accordance with Pipeline and Hazardous Materials Safety Administration
(PHMSA) safety standards. These standards are intended to minimize the risk