Medição de vazão em escoamentos gás-líquido por meio da técnica da dupla queda de pressão: análise da variância dos parâmetros de saída em função dos parâmetros de entrada

Abstract

The flow measurement in multiphase flows is a current technological challenge. Challenges that regard mainly the measurement uncertainty. Among the technologies that can measure the flow of each phase in a multiphase flow, dual pressure drop technique has been highlighted in the industry. Although already in use, multiphase metering systems that operates using the double pressure drop technique also make use of proprietary technology. In order to estimate the uncertainty of a measurement, it is important to know the sensibility of each variable in the process. This research is dedicated in evaluating the sensibility of pressure drop in the flow measurement of gas-liquid two-phase flows by double pressure drop technique. The evaluation of the sensibility of the differential pressure taps (input parameter on the model) was performed through random disturbances and the consequent variability in the measurement of the void fraction and the total volumetric flow (output parameters) were computed. It was found that a variability in the pressure drops with a standard deviation (SD) of 1% returns void fraction SD of 2.69% to 9.33%, and 1.15 to 8.02% for the velocity, depending on the flow condition. It was also observed that larger SD for the void fraction are found when the void fraction is low (<0.5) and SD larger for velocity when the void fraction is high (> 0.5).