Commissioning A New Multiphase Pump Visualization Test Rig To Investigate The Internal Flow Field And Its Connection With Pump Performance

LecturePumps with helico-axial impellers are used to boost mixtures of gas and liquid, for instance in subsea production of unprocessed oil and gas. Experimental data is essential to fully understand and characterize the internal flow, as well as for validation and improvement of numerical modeling techniques. Here we describe the commissioning of a test rig that enables visualization and measurements of the pump’s internal flow field. The test rig’s pump unit design contains three impeller stages that are 50 percent downscaled relative to a full-scale version previously tested.A reduction in nondimensional head, flow and efficiency relative to the full-scale pump can be attributed to lower Reynolds numbersand an increased relative impeller tip clearance. The tested head curves on single phase water exhibit a transition where the negative slope is replaced by a flat curve when reducing the volumetric flow rate below a certain value. Despite the downscaling, this change in slope occurs at the same relative flow rate as for the full-scale pump. This suggests that the test rig can be used to replicate the characteristics of the full-scale performance and flow field in pumps with helico-axial impellers. Varying the impeller tip clearance allowed for an estimate of pump head with the equivalent clearance as for the full-scale geometry. A Morrison number of 0.03 could then be established for the pump.The impeller tip leakage flow and two recirculation zones in the diffuser channels were identified in a preliminary view of the internal flow field at two percent gas volume fraction and part-load operating conditions. Operation at low relative flow rates and high gas volume fractions led to system surge and slugging in the flow loop. Increasing the inlet pressure and temperature significantly improvedthe situation, allowing stable operation at lower relative flow rates. Modifications to avoid gas coalescence through the pump inlet could also further widen the operational envelope at high gas volume fraction

The Effect of Fluid Viscosity on Hydrocyclone Performance: Design and Commissioning of an Experimental Rig and Results

Hydrocyclones are used in the process industry for a variety of applications. The product streams from the wells in the oil and gas industry include produced sand, which have to be removed as it interferes with control and instruments. There is also an environmental concern, which includes regulations for the content of hydrocarbons in the disposed sand. The existing knowledge of sand separation by cyclonic technology is largely limited to the separation from pure water. The future oil industry, however, faces challenges with heavy oil and non-standard particles. If the oil is heavy, the water-oil separation is poor and the sand therefore needs to be removed from a liquid phase with a considerable content of heavy oil. How the oil content will affect the cyclone performance is not understood or theoretically described. This thesis is mainly focused on solid removal from viscous liquids. An experimental rig has been designed and commissioned, and results from both experiments and CFD are presented. The results from this thesis include not only the affection of the fluid viscosity on the separation performance. It includes results for the pressure drop, and also the flow split distribution that we have when the hydrocyclone is operated with an underflow. As the viscosity of the carrier fluid increase, the separation efficiency decreases. The same is the situation with the pressure drop across the cyclone. When the viscosity of the fluid increase the pressure drop is reduced which is the opposite of what we would expect related to normal pipe flow. The by-pass ratio, which is the amount of suspension that exits through the apex of the cyclone, is increased at higher viscosities. The results from this thesis are highly valuable for the process industry. Even though more experiments are needed to fully understand the phenomena's described in this thesis, it is a leap in the direction of applying cyclonic technology in new areas. If the sand can be removed in a controlled and automated manner, the process systems can be operated with better control and safety. The lifetime of the equipment can be prolonged and allowing more sand to enter the production train can speed up the production