Pulsation Acoustics

Paper No. 51

J. C. Wachel/S. M. Price, Pipeline Engineering Symposium — 1988, PD-Vol. 14, Book No. 100256.

Pulsation accumulators are used in reciprocating pump installations to reduce pump manifold pulsations and to attenuate pulsations transmitted into the piping. The pump and piping system form a complex acoustical system which has many acoustical and mechanical natural frequencies and the potential for high vibration and component failure problems. Many times the pulsation characteristics of the system are not calculated prior to installation, and an accumulator is selected based on pressure and flow rate criteria. In some cases, this is acceptable as can be attested by the numerous installations that are installed and have operated successfully without problems. However, many installations do experience high vibrations, piping and component failures, cavitation in the suction manifold, and generally poor reliability. These problems are often the result of the failure to consider the system’s acoustical characteristics when selecting an accumulator. The effects of several different types of accumulators in a three pump parallel system were studied using a digital computer program which models the pulsation characteristics of pump and compressor systems. Detailed computer analyses were performed on bladder gas-charged appendage and flow-through accumulators, the non-bladder, flow-through, gas-charged accumulators, and all-liquid Helmholtz filters. These results indicate that the off-the-shelf accumulators can be effective in some cases, but can combine with the particular acoustical characteristics of the system to amplify pulsations in other cases. In addition, the interaction between the individual pumps in a parallel installation can cause severe amplification of the pulsations. Guidelines are presented for the selection of pulsation filters for pump systems and the type of analyses that should be performed in the design stage.

 

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