Ultrasonic classification of gases using principal component analysis

On-line measurement of the energy content of natural gas is of interest for both industry and customers, since the energy content determines its monetary value. Experiments with pulsed ultrasound show that, in addition to changes in speed of sound and acoustic attenuation, there is also a change in the shape of the sound waveform. In this paper we investigate the feasibility of using Principal Component Analysis (PCA) to quantify this change in pulse shape. The principle is evaluated for Oxygen and Ethane, for different pressures and different temperatures. The results show that by using PCA, it is possible to distinguish between pulses that have propagated through Oxygen from pulses in Ethane.