Aplicação de sensores de impedância para determinação de vazão em escoamento bifásico

Abstract

By the discovery of Pre-Salt oil reserves in Brazil, a growing demand for advanced instrumentation found place. For instance, new sensor technology in flow rate measurement has been developed and made available through research projects, aiming to determine with greater accuracy to monitor in real time parameters related to the production and transportation of gas-oil mixtures. This work proposes the study and application of the wire-mesh sensor in conjunction with a Venturi tube applied in two-phase flows, in order to estimate individual parameters of the phases flow such as void fraction, velocity and flow rate. Data from two consecutive wire-mesh sensors installed in a pipe and cross-correlation techniques is used to estimate gas flow velocity. Since the limitations of this technique on some types of flow, we resort to the use of Venturi as an alternative for further investigation. In addition, four models from literature for the classical relationship between pressure drop and flow rate through constrictions have been implemented for the estimation of the two-phase flow rates and tested. Through an experimental flow loop, data of the superficial velocities of the phases were obtained in various scenarios of a horizontal flow, taking into account their flow map and thereby enabling the determination of the sensor with the best response. The main contribution of this study is therefore to point out the main positive and negative aspects of each flow rate measurement device tested, and thus base the use of each of them in particular conditions under two-phase flow. As a possible substitute for the wire-mesh sensor, a rod sensor and its operating electronics were also preliminarily constructed and tested, which is simpler and less intrusive than the mesh sensor.