ABSTRACT

An ultrasonic multiphase flow metering concept has been proposed and investigated. The concept was based on the combination of non-invasive and non-intrusive ultrasonic sensors and a slug closure model. The slug closure model was based on a "slug unit" model to infer the gas and liquid phase volumetric flow rates.

The slug characteristics obtained by non-invasive and non-intrusive ultrasonic techniques were used as inputs to the slug closure model which calculates the factors K1 (Liquid), K2 (Liquid), K3 (Gas) and K4 (Gas). These factors are functions of the slip ratio in the slug body, flow profile, Co, drift velocity, Vd, liquid holdup and gas void fraction in slug body, slug length, film length, and the total length of the slug unit. Based on ultrasonic sensor measurements, the slug translational velocity was estimated and the slug closure model used to calculate the gas and liquid phase volumetric flow rates. Air and water slug flow data were gathered and processed for a range of superficial velocities: VSL=0.3 to 1.03 ms-1 and VSG=0.6 to 3.01 ms-1. The target metering relative error of 5% for both phases was not achieved for the conditions examined. The liquid phase percentage errors ranged from −63.6% to 45.4% while the gas phase percentage errors ranged from −14.6% to 42%.

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