Acoustic Analysis

Reciprocating gas compressors and liquid pumps generate periodic complex dynamic pressure waves – pulsations. These are modified by the cylinder passages, connection arrangements and pulsation dampeners before they enter the piping system. Resonances in the pipework or in the process vessels can amplify the pulsation levels, causing high dynamic pressures in the system.

PIPAC® is Spectrum Fluid Dynamics’ world renowned acoustic analysis software package, which provides a robust acoustic analysis of reciprocating compression applications and has over 30 years of proven success in the field. It is used to predict the dynamic acoustic pressures and forces in complex connected pipe systems, working particularly well for complicated multiple machine applications.

PIPAC® software is able to simulate stepless ‘hydrocom valve’ systems, which are an increasingly popular variable unloading mechanism, however present particular challenges in terms of pulsation control.

During the Acoustic Study pipework pulsation levels are reviewed, along with associated net shaking forces, with particular attention paid to pulsations at sensitive locations such as non-return valves, flow meters and pressure relief valves. Pulsation levels are also predicted/reviewed at the compressor cylinder flanges, in order to prevent compressor valve damage, and the impact of pulsations on compressor efficiency is also considered.

Pulsation control requirements are detailed in API Standard 618, which includes recommended limits for pulsation levels in pipework and at the compressor cylinder flanges, and guidelines for pulsation dampener performance.
Typical recommended modifications to control pulsation levels include internal pipework orifice plates or altering the diameter of sections of pipework, to detune or break up acoustic resonances respectively. In extreme cases additional vessels or alterations to pipe lengths are recommended. Care is taken to minimise the impact of recommendations on client’s pipework, on the process itself and on pressure relief systems.