Experimental study on droplet size of dispersed oil-water flow

Abstract

Experimental investigation on droplet sizing measurement techniques both in flow of oil-in-water dispersion and water-in-oil dispersion were performed at the Statoil multiphase flow laboratory in Rotvoll. The focus of these experiments was to analyze the accuracy of chord length distribution (CLD) measured by focus beam reflectance measurement (FBRM technology) in comparison with the droplet size distribution (DSD) measured by a particle video microscope (PVM technology). A beaker ? batch test and a flow loop test were employed for a variety of oils spanning over an order of magnitudes in viscosity. The PVM was found to be a useful and accurate measurement device for determining the real droplet sizes and as a calibration method for the FBRM. In the beaker test, The Sauter mean diameter d32 was found to be proportional to the maximum (99th percentile) droplet size for both oil-water emulsions and water-oil emulsions. Since the CLD values were underestimating the size in comparison with DSD values, an empirical correlation was developed based on a log-normal distribution to improve the predictive power of the CLD. The dynamic properties of both FBRM and PVM probes were evaluated in beaker tests and flow loop tests. The beaker tests were found to be a reliable and reasonable alternative to flow loop tests. The simplicity of both testing and data collection, combined with the reduced effect of distance between the probes, allow the beaker tests to provide a good estimate of the uncertainty of the FBRM measurement for the water-oil flow in the pipe.