The presence of sand particles in oil and gas production streams means that choke valve manufactures must consider new types of valve design which will inherently reduce susceptibility to solid particle erosion. Computational Fluid Dynamics offers a potential tool to assist the design process. The overall aim of the present study is to identify the limits of standard CFD models when applied to the type of complex geometries found in multi-orifice choke valves. Actual erosive wear has been predicted first for a simple geometry using the erosion equations of Neilson and Gilchrist (1968). Comparison of expeirmental material loss with predicted loss is encouraging, as it shows that realistic estimates of erosion can be made for the case considered with a simple erosion equation and standard models for fluid/particle motion (although futher work is required to complete the study). It has also been shown that CFD simulations can predict the pressure drop across multi-orifice choke valves for a range of opening positions. Comparisions of predicted pressure drop with experimental data indicate accuracy within 3 percent when the valve is fully open. However, when the valve position is such that partially open holes within the valve present only a sliver of open area to the flow, the uncertainty of predicted results increases. Significantly more cells could be required in such regions. Particle trajectory calculations indicate that proedictions of erosive wear in multiorifice choke valves are likely to reflect behaviour known from field and experimental experience.
展开▼
