A Novel Method for Phase Distribution Measurement in Water Continuous Two-Phase Flow

Multiphase flows are occurring in several areas of the process industries. It is the concurrent flow of a mixture of fluid and solid components/phases. The multiphase flows are dependent on the flow regimes, the pipe orientation and the flow properties of the constituent phases such as the flow velocity and the volume fraction. Solids-liquid flows, such as slurries it occurs in horizontal and inclined pipes. Slurries have been used for transporting solid materials over long and short distances in various industries; these industries include the oil and gas industry, the mining industry and the food industry. Within these industries, the measurement of the multiphase flow parameters such as the local volume fraction distribution and the local axial velocity distribution of the solids dispersed in liquid in slurries are required parameters, for example for quantifying the local volume fraction for flow optimisation.

The individual phases within the multiphase flow can be unpredictable and time dependent. Therefore, it is important to constantly monitor and measure the local flow parameters. The measurement of the local flow parameters in multiphase flows is very challenging. There are several solutions for measuring these flow parameters such as invasive sensing techniques, which have the tendency to alter the flow regime, while the non-invasive techniques allow for measurement without altering the flow profile.

This thesis proposes a novel design and development of a non-invasive phase monitoring device PMD, which determines the local solids volume fraction of a discontinuous phase dispersed in an electrically conducting continuous phase of a multiphase flow. Extensive simulation was carried out to validate the design and optimisation of the electrode probe to be used for acquiring the boundary measurements. In this thesis, the associated electronic circuitry for the PMD were designed, signal processing and a relevant reconstruction algorithm were also developed for acquiring the boundary measurements and presenting the measurement information quantitatively and qualitatively respectively.

A novel reference apparatus was designed as an accurate point of reference to investigate the accuracy of PMD. A series of experiments were carried out in order to measure the local solid volume fraction of the dispersed phase for various simulated non-uniform and uniform flow conditions. The results obtained indicate good quantitative agreement with reference measurements of the local solids volume fraction. The local volume fraction measurement technique described and presented in this thesis, is simpler, more accurate and less expensive than popular techniques such as the dual-plane Electrical Resistance Tomography (ERT).