KL3 Novel Approach to Emergency Pressure （KL3紧急压力的新方法）.pdfVIP

KL3 Novel Approach to Emergency Pressure Relief Design Using Calorimetric Methods Francis Stoessel Schweizerisches Institut zur Fˆrderung der Sicherheit Kly beckstrasse 141 4002 Basel Technical regulations require emergency pressure relief systems in order to protect closed and heated vessels from overpressure [1]. Many chemical reactors correspond to this definition and are therefore to be equipped with a pressure relief system, consisting of a safety valve or a rupture disk followed by a piping system to a catch pot. As the pressure reaches a predefined level, called the set pressure, the safety valve or the bursting disk opens, allowing a depressurization of the vessel. Such protection systems were traditionally designed for gas or vapor flow and non reactive vessel contents. But experience has shown that with reactive systems, two phase flow occurs, i.e. liquid is entrained with the gas or vapor. Such a flow requires larger sections for the pressure relief system. As a consequence of pressure relief, the reaction mass leaves the reactor to be transferred to a safe place, i.e. a catch pot, which retains the liquid phase and allows the vapor or gas phase to leave to a scrubber, a flare or the atmosphere. Thus the design must be performed using a specific methodology, as DIERS, which accounts for two phase flow [2, 3]. It becomes obvious that such a system cannot be used as a primary risk reducing measure. In fact according to IEC 61511 [4] it is used as an emergency measure, after all the means of safe process design, process control, safety alarms and interlock systems were used. Thus it is a last resort safety system. Moreover its design must be performed with ext