Wet Gas Flow Measurement Based on the Instantaneous Frequency Stability of Vortex Meter Using CWT Ridge Method

Wet gas two-phase flow is widespread across industrial sectors, and accurate metering of Type I wet gas is critical for fiscal accounting and resource allocation, with gas flow measurement being the primary concern. In order to achieve accurate measurement of Type I wet gas using only a single flowmeter, a new wet gas metering model is proposed by using the instantaneous frequency stability of vortex meter. The continuous wavelet transform (CWT) ridge method is applied to extract the instantaneous frequency and amplitude of the vortex signals, and its extracted accuracy is validated by using the amplitude-phase modulated (AM-PM) signal. The vortex signals in wet gas flow are found to be low-frequency modulated with frequency modulation ratio smaller than 0.05, and the more the liquid fraction is, the more obvious the modulation effect is. Then, the scale parameters of the meter overreading and modulation feature are discovered by estimating the vorticity transport process in droplet-laden flow, named density ratio, liquid mass loading and entrainment, and the uniform equations of meter overreading and normalized standard deviation (NSD) of ridge frequency are developed. Finally, the wet gas metering model is established by the simultaneous equations of meter overreading and NSD(f). The predicted results indicate that 94.5% of the data points are within ±1.0% error bands with an uncertainty of 0.52%. A comparison was conducted between the proposed method and existing methods. The merits of the proposed method are simple to operate, cost-effective and high precision.