Damping of Self-Excited Pressure Pulsations in Petrodiesel Pipeline

Abstract

A pumping station in a fuel storage suffered from pressure pulsations in a petrodiesel pipeline. Check valves protecting the station against back flow made a big noise when disc hit a seat. Due to employees complaints we were asked to solve the problem, which could lead to serious mechanical problems. Pressure measurement in the pipeline showed great pulsations, which were caused by self-excited oscillation of control valves at the downstream end of pipeline. The operating measurement did not catch it because of too low sampling frequency. One dimensional numerical model of the whole hydraulic system was carried out. The model consisted of check valve, pipeline and control valve, which could oscillate, so it was possible to simulate the unsteady flow. When the model was validated, a vessel with nitrogen was added to attenuate pressure pulsations. According to the results of numerical simulation, the vessel was installed on the location. Subsequent measurement proved noticeably lower pulsations and almost no noise.

Check valve slam analysis in pumping station

“…Choice of a wrong dimension or a wrong type leads to pressure pulsations and check valve slam, which influences lifetime of the check valve and the whole pipeline system. Problems with check valve slam are very common in many industrial applications ( [3] or [4]), also authors of this paper have already dealt with it [5]. The valve suffered from self-excited pressure pulsations, but in that case, the problems were not caused by check valve itself, but control valve in the different place of the system.…”

“…One-dimensional flow in the pipeline follows momentum equation (4) and continuity equation (5). These equations are solved with Lax-Wendroff method.…”

Quarter wavelength resonator in experiment and simulation

“…Self-excited vibrations are difficult kind of these problems since the change in a system might only lead to a change of frequency. [1] Some of the problematic vibrations can be silenced using mufflers and resonators. [2] Resonance of acoustics cavities was studied for example in [3] in relation to various length and cross-section ratios.…”

Experimental investigation of the check valve behaviour when the flow is reversing

“…The check valve also can make problems with selfexcited pressure pulsations: The oscillating control valve at the downstream end of pipe causes troubles with check a e-mail: himr@fme.vutbr.cz valve slam at the upstream end [5]. An example of the pressure surge due to the check valve slam after the pump stoppage is shown in the figures 1 and 2.…”