General Fundamentals Of Two-Phase Pressure Relief

All further considerations shall remain limited to pine vapour phase systems, because the design of hybrid and gas generating systems requires the additional information of the individual permanent gas generation rate. Such systems must each be characterized experimentally before the first run on the plant This must be followed by the second step of assessing the compatibility of process and plant design. 

In the investigation of vapour phase systems it is assumed that the reactor operates as a closed system and that the total pressure in the reactor corresponds to tiie vapour pressure at all times, which itself is related to the current temperature. The relationship between vapour pressure and temperature may be described vnth the simplified An-toine-relation 

Vapour pressure systems have the advantage of reaching and passing through the pressure and temperature maxima at the same time. At the begin of relief the system is in a state of overheating with respect to ambient pressure. If the relief S3rstem was 

From a construction point of view top or bottom venting are discriminated. In the majority of cases top venting with the help of a bursting disk or a safety valve installed on the reactor lid is preferred. This is the only alternative, which in principle provides the chance of a single phase vapour flow relief situation, e.g. if the filling level is low and if at the same time the system is not foaming. This kind of relief situation requires the smallest effective vent area. All further descriptions refers to the top venting situation only. 

---