Estimating Vapor Cavity Collapse Pressure Surges in a Crude Delivery Terminal

When crude oil flows into a delivery terminal, closing a valve could create a vapor cavity within the pipe downstream of the valve and the subsequent vapor cavity collapse can generate high surge pressures. The surge pressures depend on several parameters including not only the delivery terminal specifications for pipe length, pipe size, and tank level, but also on the initial operational parameters of flow velocity and crude grade, as well as the valve characteristics of valve curve, closing time, and flow coefficient. A parametric and transient study was conducted on the vapor cavity formation and collapse phenomena through varying combinations of these eight parameters, using the discrete vapor cavity model. The results obtained were used to rank the effect of the eight parameters on transient pressures generated within such systems. In addition, a methodology was developed that allows the use of estimation tables to quickly and reasonably estimate the maximum surge pressures, assess mitigation strategies, and optimize general delivery terminal operations. Two case studies are provided to demonstrate the application of the estimation methodology.