Dynamic simulation of the behaviour of pressure relief systems

Pressure relief of near critical processes working at two phase region is s imulated dynamically. The design procedure for pressure relief devices is d emonstrated by an example. The example shows that the required relieving ar ea of the safety valve depends on time and scenario. This is the basis for the selection of the type and the size of safety valve. When the process re lieves through the selected valve the outflow and the pressure of the prote cted vessel varies dynamically. This phenomenon cannot be discovered by the static approach that is normally used in the design of pressure relieving devices. The traditional sizing equations, API 520 and DIERS, are also diff icult to apply in near critical region and they include coefficients that a re sometimes difficult to obtain. The sensitivity may be so large that a di fferent size of the relieving device is selected depending on the model. Us age of two common models, API 520 and DIERS, in the region of two phases is discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.