GMC 2010: Low-Loss Pulsation Control Page 1 Low-Loss Pulsation Control GMC 2010 By Marybeth Nored (SwRI), Buddy Broerman (SwRI), Klaus Brun (SwRI) and Gary Bourn (El Paso) Introduction The advancement of reciprocating gas compressor technology for pipeline gas transmission has been made possible, in part, due to the effectiveness of the compressor pulsation control system. The vast majority of current high speed compressors operate less efficiently than low speed compressors due to the higher flow rates which lead to higher associated flow related losses through the valves, orifice plates and the pulsation filter bottles. Also, with higher horsepower machines operating over a large relatively high speed range (800- 1200 RPM) pulsation amplitudes tend to be significantly higher, leading to higher dynamic losses and high risk vibrations on the manifold and cylinders. Advanced pulsation control techniques are needed to accommodate the increase in compressor horsepower and the range of running speeds as well as the variation in operations. The current GMRC pulsation control research program is developing concepts to control pulsations more efficiently and effectively than the orifice plates and standard approach to filter bottle design, used in the past. Two of the more promising and mature advanced pulsation technologies developed by GMRC at Southwest Research Institute are the Pressure Recovery Insert (PRI) and the Virtual Orifice (VO). Both devices can be used to control high pulsations from a piping resonance, excited by one or more compressor orders. The two devices were developed to reduce the high losses associated with orifice plates (commonly used as insertion plates to reduce the amplitude of high fluid pulses). However, the two technologies are designed differently and mitigate pulsations through entirely different mechanisms. This paper will review both technologies and field test case studies to show the benefit of these low-loss pulsation controls. Options for nozzle resonance control have been one of several areas addressed more recently by the GMRC pulsation research namely because a large population of existing cylinder nozzle orifice plates may be eliminated through advanced methods of pulsation control. The nozzle resonance controls can also be implemented in a retrofit manner relatively easily, at a lower cost than new filter concepts or system / station control concepts. The standard practice for nozzle resonance control has utilized orifice plates to dampen the high pressure pulse at the resonant frequency. This is one method of attenuating a resonant response which can be added to the system design at a low cost. Its primary disadvantages are the pressure loss associated with the orifice plate and a potential for increased pulsations in the lower frequencies (typically at 1x and 2x compressor running speed).