HOUSTON – Dresser-Rand Group has performed a noise test for Statoil regarding a compressor for a platform in the North Sea, 40 km (25 mi) west of Bergen, Norway. This involved use of a 30-in. diameter pipe resonator array, the largest ever produced, the contractor claims.
The test, performed at Dresser-Rand’s complex in Le Havre, northern France, intended to validate estimated noise attenuation on the compressor (there are two trains of DATUM D18 centrifugal compressors operating on the platform).
Dresser-Rand installed a diffuser resonator array at the first and last stages of the compressor and a pipe resonator array on the inlet and discharge process piping.
According to Scott Wisler, director of Centers of Technical Excellence at Dresser-Rand, “the initial choice was to use internal diffuser resonator arrays, but Statoil asked us to also install pipe resonator arrays on their 28- and 30-in. pipes.”
To verify the attenuation of sound by the array, sound pressure levels were generated by a loudspeaker at the Le Havre facility and measured in ducts upstream and downstream of the array. Measurements included a comparison of the sound level with a straight pipe spool piece and a pipe resonator array.
Results showed that the pipe array could achieve more than 10 dB attenuation for the frequency range corresponding to the speed range of the compressor. Since the measure of sound level is a logarithmic function, a 10 dB reduction corresponds to a 90% reduction in sound power, Dresser-Rand says.
Turbo compressors typically output 90 dB or more, with the main noise originating from the impeller aerodynamic interaction with stationary components. The generally accepted solution, the company says, is to attenuate, or reduce, the noise at its source.
“Once installed, improvements are immediate and dramatic, and the benefits in terms of reductions in noise and vibration damage will last for the life of the compressor,” Wisler said.