Always growing capacities, size of machines and performance requirements and often changing plant layout arrangement, determine a continuous challenge for designers of machines and plants. For hyper compressors and connected piping system, the goals of safety and reliability can be achieved only with a deep analysis of all operating conditions to determine pulsations and vibration effects. Innovative methods of simulation, modeling and technologies improve the possibility to evaluate piping and compressor behavior, allowing to obtain the efficiency and a smooth and safe plant operation.

The combination of booster-primary and hyper compressors reaches very high pressures in Low Density Polyethylene Plants. Pressure and flow pulsations due to the unsteady flow generate an acoustic energy that interacts with the mechanical system of the plant, causing mechanical vibrations. Pressure pulsation and vibration control on relatively high pressure piping is necessary to prevent failures caused by cyclic stresses due to both internal pressure fluctuations and vibrations generated by the compressor. To increase the compressor performance, safety and reliability designers require advanced methods of simulation to evaluate piping and compressor behavior during the initial stage of the project. The paper will investigate the modeling of the pulsation with the influence of fluid-dynamic aspect related to the gas and the relevant system interaction.

The development of the market for large scale plants, driven by their greater economic return requires processing equipment with increasingly larger capacities. This includes the reciprocating compressors used in Low Density Polyethylene Plants. The design of the high pressure piping associated with hyper-compressors, particularly for reactors and intercoolers, requires careful analysis. Due to the lengthy delivery times for such components, decisions regarding the diameter of high pressure piping usually have to be made at an early stage. Because of the importance of pressure pulsations that occur during operation, an analysis has to be made based on preliminary information available. Such a simulation can be made using reasonable assumptions about the length of the piping involved, and the configuration of both the compressor and the cylinders. At this point, the piping diameter can be confirmed and later, when the plant arrangement has been finalized, a more detailed analysis can be performed which may result in minor adjustments to the piping design.