Session: HT-02-01 Impulsively Loaded Vessels

Paper Number: 122773

122773 - Visualization of Combined Decomposition and Relief Processes in High-Pressure Systems 

Visualization of Combined Decomposition and Relief Processes in High-Pressure Systems

Aaron Röblitz, Jarne Berning, Markus Busch*

TU Darmstadt, Ernst-Berl-Institut für Technische und Makromolekulare Chemie,

Peter-Grünberg-Str. 8, D-64287 Darmstadt, Germany,

*e-mail: markus.busch@pre.tu-darmstadt.de

 

To ensure the safe operation of polymerization plants, the prevention of decomposition in the production process is a decisive factor. As a result of inadmissible temperature increases, for example, due to insufficient heat dissipation, or due to poor mixing of the reaction mixture, hotspots can nevertheless form, which can lead to decomposition and thus to a rapid increase in pressure. To prevent damage to the system as well as to guarantee safe operation, safety valves are implemented which can relieve the system in case of an unacceptable pressure rise. Since the design of the safety valve is of decisive importance in this context, a sound knowledge of the decomposition and relief processes taking place is essential. These variables can be determined using fast measurement technology such as thermocouples and pressure sensors. For the analysis of the running processes and their influence on each other, a visual evaluation becomes necessary. This also allows the flame front geometry and velocity to be investigated, as well as the influence of the relief on the same.

A view cell with a volume of 34 ml was used to carry out and investigate the decomposition or discharge processes described. A high-speed camera is used to visualize the phenomena that occur. In addition, the temperature and pressure changes can be recorded by a fast-measuring sensor system. Decomposition is initiated by the formation of a hotspot through the annealing of a tungsten wire coil connected to a thermocouple via a ceramic piece. Relief is provided by a pneumatic valve, and the relief as well as closing pressure can be set in advance. For visual evaluation, a tracker program is used to determine the position of the flame front as well as the velocity. Together with the pressure and temperature data obtained, a description of the decomposition and relief process can be made.

After the pure decomposition process and decomposition with subsequent complete relief had already been examined in previous work ^[1], the next step was to carry out a series of tests in which the pneumatic valve was supposed to close again automatically at a previously set pressure.

Furthermore, tests were carried out at higher initial pressures to investigate not only the processes occurring under high-pressure separator conditions but also under reactor conditions of the LDPE process. In particular, the changed density and viscosity of the system play a crucial role, which is why the influence of these parameters on the decomposition and relief process should be determined.

[1] A. Röblitz, M. Busch, Pressure Vessels & Piping Conference (2023)

Presenting Author: Aaron Röblitz TU Darmstadt

Presenting Author Biography: Aaron Röblitz is in the 4th year of his Ph.D. studies in the research group of Prof. Busch at the TU Darmstadt. His research topic is safety engineering with a focus on the LDPE process. In this context, he is investigating decomposition and relief processes using a view cell as a reactor. Supported by simulation models, the aim is to improve the understanding of the processes taking place and thus to optimize the safety of these processes.

Authors:

Aaron Röblitz TU Darmstadt
Jarne Berning TU Darmstadt
Markus Busch TU Darmstadt