Community Research and Development Information Service - CORDIS


Emergency relief systems (ERS) are installed to protect process vessels from the catastrophic effects of an excessive overpressure and subsequent rupture. Sizing of adequate ERSs for reactive systems is particularly difficult since an industry-wide standard does not exist. This is mainly due to the scarcity of knowledge of off-normal process conditions. Most often, relief devices are only sized for the vapour load, which is ineffective if incomplete disengagement of the vapour from the liquid takes place and results in two-phase flow, since generally two-phase flow requires a larger relief capacity (possibly up to 10 times in area) than when the venting is pure vapour. The purpose of this work is to discuss the phenomena associated with reactor relief and considerations relevant to the process design of reactor relief systems. The approach to vent-sizing evaluation for tempered, gassy and hybrid systems is presented as well as an up-to-date methodology for selecting and using the appropriate sizing methods.

Additional information

Authors: AL-KHUDHAIRY D H A, JRC Ispra (IT)
Bibliographic Reference: Paper presented: Friendly Batch Chemical Plants, Barcelona (ES), Sept. 25-28, 1990
Availability: Available from (1) as Paper EN 35726 ORA
Record Number: 199011705 / Last updated on: 1994-12-02
Original language: en
Available languages: en