Low shear pump is important equipment that in the liquid cyclone separation technology provides swirl vascular resistance compensation for loss. Its oil droplets sheared size for oil and water mixed solution, it will directly affect the liquid - liquid separation efficiency of the cyclone separation system. For the two-phase separation of oil and water, the density difference is generally smaller and difficult. To achieve the separation, it requires a larger inlet tangential velocity, which usually requires booster pump to provide energy for the mixed solution. However, the conventional pumps’ shear forces are larger, and result in oil droplets broken, the particle size decreased, so that the cyclone is difficult to separate. Therefore, they need for a dedicated low shear pumps, to ensure that the minimum amount of broken droplets in the pumping process, create a favorable conditions for the further separation of oil and water.
Fluid Mechanics Laboratory, University of Petroleum in a large number of experimental measurements and theoretical basis for oilfield pumps work and renovation experience, develop and improve a set of three-dimensional flow calculations and design process. Use this procedure to calculate the low shear prototype pump flow velocity distribution, the pressure distribution and the flow channel wall boundary layer momentum thickness. And the important parameters such as blades hydraulic load distribution to evaluate the merits of the pump hydraulic design. According to the criteria of the centrifugal pump impeller has been formed to optimize the design, re-design the low shear booster pump impeller. Its hydraulic design idea is as follows: 1. Select a lower speed (less than 1500r/min) to achieve supercharging effect. This is due to the higher speed will result in intense shear oil droplets leaving broken, reducing the separation efficiency. 2. Avoid or reduce the low shear pump impeller outlet flow separation region-wide. Pump flow field laser speed results show that due to the compounding effect of pump rotation and blades curvature, formation of a strong jet wake structure. This is the turbo machinery shear most dramatic area. 3. Under the premise of guaranteed shear pump design conditions parameters, as much as possible to broaden the internal flow channel, so that the pressure gradient between the two small blades is small, avoid excessive impacts between fluid and solid wall to make oil particles broken. 4. Try the shear pump to work in the efficient workspace. Experiments show that the shearing action of shear pump is the smallest in the efficient work area, and the efficiency is the highest.
Studied from the theoretical and experimental two methods for low shear centrifugal pumps, According to the characteristics of low shear, primaries existing centrifugal pump, transform the design impeller leaf type, flow and other parameters, and verified by experiment. Worked out a design rule of low shear centrifugal booster pump, this has a certain guiding significance for the optimized selection of shear pump.