Page 36 - Compression Machinery for Oil and Gas

26 SECTION I Fundamentals of Compression

Industry standard sophisticated programmable logic controller (PLC) equip-
ment is utilized most often in complex applications or regulation of equipment
that requires more than simple on/off control, or where it is not feasible to trans-
mit data and signals via communications lines to control equipment. Modern
electronic controls are advantageous because they can be interfaced directly
to commercially standard and available PLCs and computers, providing flexi-
bility in operation and ease of expansion. Because of the variety of technical
operating equipment found within a compressor station, the most efficient
and cost-effective control systems are combined systems which include
components of all types of control equipment. Electronic and electric controls
are interfaced with mechanically operated controls on devices to provide
safe and extremely accurate control systems with standard designs and
reasonable costs.

Air Filtration Requirements

Ambient air to be used for the combustion of fuel in an internal combustion
engine or gas turbine must be provided in the right quantity and quality. The
air inlet system primarily consists of an inlet air filter in the piping or ducting
to direct the air to the engine or turbine. Silencers may also be required to con-
trol with the noise created by the flow of air and by the engine or turbine itself.
Ambient-rated turbocharged engines as well as gas turbines also require some
means of controlling the temperature of the air entering the engine if the full
power is to be developed.

Operating Company Preferences
Certain operating companies may have preferences for new compression needs
based on their historical experience and existing installed compression machin-
ery. There may be logistical benefits to selecting certain compressor types based
on staff familiarity, training, spare parts, local suppliers, etc.

Packaging Issues

Most high-horsepower, slow-speed reciprocating compressors (typically less
than 500rpm, either separable or integral units) are installed with a direct mount
to a concrete foundation. This allows for the most rigid foundation to react to
any substantial unbalanced forced. This direct to foundation mounting approach
involves significant effort in the field during the installation process. Most mod-
ern high-speed compressors (over 500rpm) are typically packaged on a steel
skid that can be assembled in a shop and then transported to site. The compres-
sor skid package allows for the compressor, driver, pulsation vessels, piping,
auxiliary system (lubrication, cooling, etc.) to all be mounted on a single, por-
table skid. This packaging approach provides advantages in assembly time,