Feasibility study on the use of side channel pumps for low viscosity fluids, with fracking or other hydrocarbon processing applications

LectureSide channel pumps typically are used in applications with low specific speed. The ratio of the low flow and high head tends to result in this niche product, located in between the classical displacement and centrifugal pumps, but uniting the advantages of both. Best experience in the design of these multistage ring section pumps is in using bearing bushings in the stages that are lubricated by the pumping media itself. This guarantees them to be low in service and maintenance time and cost and the pump has no need for another lubricant which contaminates the pumped media. The side channel pumps are a good solution for use with low density (below 5.8 lb/gal / 700 kg/m3), and low viscosity hydrocarbons (lower than 4.3e-8 lbf s/in2 / 0.3 cP), e.g. in fracking applications or petro- chemical use. The investigated side channel pump is able to generate and handle high pressures at low flows, but in a number of hydrocarbon applications with low viscosities, low NPSH-values or with relatively high percentage of entrained gas, some material failure in the bearings is discovered. The working principle of the pump and the performance characteristic is briefly explained. One of those characteristics is a highly transient pulsating pressure, resulting in high forces on the shaft and the impeller. The reasons for the pulsation and some methods to deal with the resulting forces are shown and explained. The high radial load, together with the low viscosity, could lead to an overload of the standard bearings and material failure. New journal bearings have to be designed. Some other possible solutions and ways to deal with the high forces are shown. The head and efficiency curves are tested on a test rig and the results are compared to numerical investigations. The pulsations and the force are determined in numerical investigations. The NPSH-value is measured and an optimized NPSH-impeller is designed and manufactured using Rapid-Prototyping. The newly manufactured impeller is compared to the original design, manufactured in two different ways (sand casting and investment casting). In the end, a modified pump, ready for the use in hydrocarbon-processing and fracking applications with amounts of gas and a low NPSH requirement is presented and the characteristics are tested on a test-rig, applying affinity laws