Design of Pressure Relief Devices for Chemical Reactors on the Basis of Adiabatic Tests – Is this always Conservative?

• Main Authors: Simon Seitz, Frank Westphal
• Format: Article
• Language: English
• Published: AIDIC Servizi S.r.l. 2016-04-01
• Series: Chemical Engineering Transactions
• Online Access: https://www.cetjournal.it/index.php/cet/article/view/3381

Is the assumption correct that closed adiabatic tests for the design of pressure relief devices are always conservative? This issue will be investigated in different reaction systems. An effect is postulated, according to which higher temperature rise rates can be reached in adiabatic pressure relief tests in comparison to those in closed adiabatic laboratory tests. This effect can be described as a “distillation effect”. To describe the distillation effect we developed a theoretical number containing the essential characteristics with respect to the energy production by a runaway system and the energy dissipated by the evaporation of solvent during the pressure relief. To investigate the effect, two different reaction systems were examined. Initially, these systems were modified based on predefined criteria. The distillation effect could not be identified by the experimental studies. In principle, the effect is expected when the reaction system has certain properties. Herewith, the reaction must have a high reaction energy and the solvent must have the highest vapor pressure in the system. Furthermore, the reaction heat must be high enough to evaporate the whole solvent and there must be enough energy to accelerate the heating of the reaction system. Overall, it was shown that the effect can be expected only in very few reaction systems.