Fluid Dynamics of Thermal Ethylene Decomposition Under Supercritical Conditions

One of the chemical industry's top priorities is to ensure that its industrial processes are safe through technical and organizational measures. In polymer production, particularly in the high-pressure synthesis of low-density polyethylene (LDPE), ethylene, a widely used raw material, is processed under high-pressure (up to 3000 bar) and high-temperature (up to 350 °C) conditions. As a result, the chemical instability of ethylene can lead to a thermal decomposition reaction.
This reaction carries the risk of a rapid rise in temperature and pressure, which is difficult to predict at industrial scale. This unpredictability is a major challenge for the design and dimensioning of safety equipment.
This work investigates the propagation speed of the thermal decomposition of ethylene under high pressure conditions and determines its influencing factors. A method was developed to observe this decomposition reaction with spatial and temporal resolution. The study focuses on the determination of the laminar flame front speed (LFFS) under different operating conditions and investigates how fluid dynamics, e.g. turbulence, influence the propagation of the ethylene decomposition reaction.