Experimental investigation of the parameters that affect droplet size and distribution for design calculations of two-phase separators.

The critical design parameter when sizing a separator is the size of oil droplets in the water phase. This study improves the design of a separator by investigating the parameters that control droplet size, frequency, and distribution. Experimental work was performed to investigate the effect of flow rates and oil layer thickness on these parameters. Experiments were performed using a transparent laboratory separator to allow the measurement of droplet properties. The Design of the Experiment (DOE) method with the Taguchi analysis was applied to investigate statistically if droplet properties are solely a function of the independent variables or if they interact. The findings show that the results can be modelled using Gaussian distributions. Droplet size distribution and the number of droplets produced are functions of the interaction between oil flow rate and oil pad thickness. The oil flow rate dominates the droplet size though layer thickness has a minor effect. The number of droplets (Frequency) increases with both oil and water flow rates but decreases with oil pad thickness. There are clear interactions between all variables resulting in different droplet frequencies for combined effects. The distribution of the droplet sizes is controlled by oil layer thickness, where the spread is seen to rise with thickness. However, interactions between the fluid flows and oil pad thickness give rise to different droplet distributions if either variable were changed on its own.

Contemporary application of microbubble technology in water treatment.

Microbubble (MB) technology constitutes a suite of promising low-cost technologies with potential applications in various sectors. Microbubbles (MBs) are tiny gas bubbles with diameters in the micrometre range of 10-100 µm. Along with their small size, they share special characteristics like slow buoyancy, large gas-liquid interfacial area and high mass-transfer efficiency. Initially, the review examines the key dissimilarities among the different types of microbubble generators (MBG) towards economic large-scale production of MBs. The applications of MBs to explore their effectiveness at different stages of wastewater treatment extending from aeration, separation/ flotation, ozonation, disinfection and other processes are investigated. A summary of the recent advances of MBs in real and synthetic wastewater treatment, existing research gaps, and limitations in upscaling of the technology, conclusion and future recommendations is detailed. A critical analysis of the energetics and treatment cost of combined approaches of MB technology with other advanced oxidation processes (AOPs) is carried out highlighting the potential applicability of hybrid technology in large-scale wastewater treatment.

Design and capital cost optimisation of three-phase gravity separators.

The separation of produced fluids is essential once it reaches the surface. This separation is achieved in gravity separators. The design and sizing of separators can be challenging due to the number of factors involved. Improper separator design can bottleneck and reduce the production of the entire facility. This paper describes the development of a capital cost optimisation model for sizing three phase separators. The developed model uses GRG Non-linear algorithms to determine the minimum cost associated with the construction of horizontal separators subject to four sets of constraints. A numerical sizing example was solved to provide the details associated with the model and the ease with which parameters can be varied to suit the user's needs. Finally, a spreadsheet comparison between results obtained from the developed model and four other extant models is carried out. Results indicated that the developed model predicted results within an absolute error of ±5m3 in most cases and a maximum of ±12.5m3 for very high gas flows in comparison to conventional models developed based on retention time theory.

Application of polymer integration technique for enhancing polyacrylamide (PAM) performance in high temperature and high salinity reservoirs.

Polyacrylamides (PAM) are widely used as water-soluble polymers producing gel in oil reservoirs to assist in oil extraction from reservoirs with high levels of heterogeneity. These gels are susceptible to degradation due to hydrolysis in harsh reservoir conditions such as elevated temperature and salinity. This study uses a polymer integration technique in attempting to optimize the performance of PAM in the enhanced oil recovery process for reservoirs with high temperature and salinity. The results show that, at high temperature, hydrolysis is suppressed and gel stability is maintained via the addition of Polyvinylpyrrolidone (PVP) to PAM solutions. The optimum composition was identified as being 20/80 wt% PAM: PVP for oilfield operations at 90 °C and a moderate salinity of 43,280 ppm. The degree of hydrolysis at 30 days was suppressed from 75% to 29.9%, with associated increases in viscosity from 11 to 38.2 mPa.s and from 18 to 44.3 mPa.s corresponding to rotational speeds of 30 and 10 rpm respectively. The issue of high salinity was considered by increasing the salinity of the optimised PAM: PVP mixture to 200,000 ppm. Under these conditions the degree of hydrolysis of the optimised solution increased from 29.9 to 46.9% and viscosity decreased from 38.2 to 28.6 and from 44.3 to 40.4 mPa.s for rotational speeds of 30 and 10 rpm respectively. 2-Acrylamido-2-MethylpropaneSulfonic acid (AMPS) was added to the mix to try to improve temperature stability. It was observed that, with an optimum composition of 18/72/10 wt% PAM:PVP:AMPS, the degree of hydrolysis decreased to 22% with viscosity levels of 30.6 and 22.8 mPa.s corresponding to rotational speeds of 10 and 30 rpm respectively.