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58,80 €ISBN 978-3-8191-0723-8Softcover172 pages109 figures305 g24 x 17 cmEnglishThesis
May 2026
New publication
Aaron Peer Röblitz
Safety-Related Investigation and Visualization of Decomposition and Pressure Relief Scenarios in the High-Pressure LDPE Process
The radical polymerization of low-density polyethylene (LDPE) occurs under extreme conditions. Insufficient heat removal, for example, can lead to the formation of local hotspots. These hotspots can trigger rapid decomposition reactions that convert ethylene into methane, hydrogen, and soot. These reactions are accompanied by severe increases in pressure and temperature. Such events pose significant risks to plant integrity, operational safety, and the environment. Therefore, designing reliable pressure relief systems is essential for ensuring safe process operation.
This work presents a detailed experimental study of the decomposition and pressure relief processes in ethylene and ethylene/vinyl acetate mixtures under high-pressure conditions. Experiments were conducted in a mini-plant with a visual high-pressure cell and fast-response measurement technology. This setup enabled time-resolved analysis of pressure, temperature, phase behavior, and flame front dynamics via high-speed imaging. The study reveals the complex interplay between thermodynamics, fluid dynamics, and reaction kinetics during rapid depressurization and decomposition. Particular emphasis is placed on non-ideal effects, such as delayed vaporization and two-phase flow, which result in deviations from classical flow models. Furthermore, this study systematically analyzes the influence of key parameters, including mass flow rate, initial conditions, mixture composition, and geometric constraints, on pressure relief performance and decomposition behavior.
By combining quantitative measurements with visual observations, research on flame propagation, reaction stability, and the interaction between decomposition and venting processes is included. These findings improve understanding of safety-relevant mechanisms and support the development of more reliable design methodologies for pressure relief systems in high-pressure polymerization processes.
This work presents a detailed experimental study of the decomposition and pressure relief processes in ethylene and ethylene/vinyl acetate mixtures under high-pressure conditions. Experiments were conducted in a mini-plant with a visual high-pressure cell and fast-response measurement technology. This setup enabled time-resolved analysis of pressure, temperature, phase behavior, and flame front dynamics via high-speed imaging. The study reveals the complex interplay between thermodynamics, fluid dynamics, and reaction kinetics during rapid depressurization and decomposition. Particular emphasis is placed on non-ideal effects, such as delayed vaporization and two-phase flow, which result in deviations from classical flow models. Furthermore, this study systematically analyzes the influence of key parameters, including mass flow rate, initial conditions, mixture composition, and geometric constraints, on pressure relief performance and decomposition behavior.
By combining quantitative measurements with visual observations, research on flame propagation, reaction stability, and the interaction between decomposition and venting processes is included. These findings improve understanding of safety-relevant mechanisms and support the development of more reliable design methodologies for pressure relief systems in high-pressure polymerization processes.
Keywords: Decomposition; Pressure Relief; Flame Front; View Cell; Discharge Coefficient; Boiling Delay
Darmstädter Schriftenreihe der Polymerisationstechnik
Edited by Prof. Dr. Markus Busch, Darmstadt
Volume 37
Other formats
Electronic publication (PDF): 978-3-8191-0665-1
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