Dynamic
Design Considerations When Modernizing a Pipeline Compressor
Station K. E. Atkins, K. S. Watson and V. W. Vaughn, 1998
GMRC Gas Machinery Conference, Denver, CO, October 5-7, 1998.
In 1995,
a major U.S. natural gas pipeline company initiated a modernization
project for four of its critical main line compressor stations
that were originally commissioned in the early 1970’s.
The modernization included improved emissions (pre-combustion
chamber “PCC” technology) as well as other upgrades
that increased the speed and therefore compressor capacity at
certain locations. A total of five integral engine/compressors
from four compressor stations were involved. At one station,
two V12 engines were increased in horsepower from 4000 HP at
300 RPM to 5000 HP at 330 RPM. At two other stations, V12/14
engines were upgraded from 4000 HP at 250 RPM to 6350 HP at
330 RPM, which included adding two power cylinders on each engine.
All five engines were retrofitted with the “best available
control technology” or BACT PCC upgrade packages from
the respective OEMs. These upgrades were very successful from
the standpoint of reduced emissions.
The effects
of the speed increases are the major focus of this paper. Such
changes have major ramifications regarding the dynamics of the
system. Pulsation, vibration and performance characteristics,
as well as the inertial forces generated by an engine/compressor
are significantly affected by speed changes.
This paper
discusses the substantial engineering effort undertaken by the
pipeline company to ensure safe, reliable and efficient operation.
Each of the following topics are discussed:
• The effects of the speed increase on the original pulsation
control devices,
• The system modifications required to control pulsation
levels,
• The conceptual differences in considering the rigid body
shaking forces versus the individual main bearing loads when designing
the tie-down system,
• Alternate counterweight configurations, as well as the
interaction between counterweight configuration and the torsional
response of the engine.
• The relevant issues of crankshaft phasing, cylinder configuration,
and rotating and reciprocating balance weight design,
• Engine force-moment calculations as well as predicted
and measured results.
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