A new robust regenerative turbo-reactor concept for clean hydrocarbon cracking

Abstract

Energy consumption in the chemical and petrochemical industries is dominated by the highly energy-intensive, high-temperature hydrocarbon cracking process. This paper offers an attractive solution to potentially decarbonise the cracking industry by direct renewable electrification whilst also improving the efficiency of energy transfer and enhancing the quality of the overall cracking process. Controlled endothermic cracking reactions are generated by direct mechanical energy transfer using a new electric-motor-driven turbo-reactor to replace the fossil-fuelled radiant unit in the conventional cracking plant. This study provides an introduction to the novel concept, focusing on how the unique three-blade-row repeating stage design is exploited in order to drive the efficient energy transfer and transformation processes used to overcome the fundamental limitations of the conventional process. More specifically, this includes increasing the primary product yield, mitigating coke deposition and improving operability. A combination of URANS and high-fidelity LES are presented in order to probe the aerothermal flow physics and interactions in the rotor and diffuser. This study clearly demonstrates how the working principals of the elemental stage can be realised uniformly across the full regenerative turbo-reactor by exploiting the robust and naturally self-adjusting concept. This work highlights the high-level of controllability of the turbomachine, which allows the cracking environment and species selectivities to be tailored during operation, for example, by conducting minor alterations to the rotational speed.