Influence of Reverse Flow Control Systems for Reciprocating Compressors on Pressure Pulsations in the Surrounding Piping
Reciprocating compressors, due to their operating principle, cause pressure pulsations in the piping system between the pipeline and the compressor. The usual way of combating these pulsations is by means of damping bottles of certain volumes, nozzles of defined sizes and pipes of defined lengths and diameters. For a specific project the design parameters of the bottles and nozzles are often determined by means of computer analysis. The gas throughput of reciprocating compressors has usually been controlled through unloading of some of the cylinder ends. This, of course, changes the resulting pressure pulsation level in the system and has to be monitored during the design phase of a new project. However, through the introduction of reverse flow control systems in recent years, much progress has been made with regard to how volume flow of compressors can be controlled more accurately. This new technology also has some influence on the pulsations around the machines. In this paper, the method of how this reverse flow control technology can be incorporated into a pulsation study is shown. By solving the governing fluid mechanic equations for compressible flow in the time domain, the influence on pulsations of a reverse flow compressor control system is shown. The resulting pressure pulsation level of a sample compressor equipped with a reverse flow system or with an on/off control is compared. It shows that generally the resulting pulsation levels of this new technology are smaller than the resulting pressure levels with a traditional on/off control system.