Abstract

Decarbonising highly energy-intensive industrial processes is imperative if nations are to comply with 2050 greenhouse gas emissions. This is a significant challenge for high-temperature industrial processes, such as hydrocarbon cracking, and there have been limited developments thus far. The novel concept presented in this study aims to replace the radiant section of a hydrocarbon cracking plant with a novel turbo-reactor. Rather than using heat from the combustion of natural gas, the novel turbo-reactor can be driven by an electric motor powered by renewable electricity. Switching the fundamental energy transfer mechanism from surface heat exchange to mechanical energy transfer significantly increases the exergy efficiency of the process. Theoretical analysis and numerical simulations show that the ultra-high aerodynamic loading rotor is able to impart substantial mechanical energy into the feedstock without excess temperature difference and metal temperature magnitude. The required enthalpy rise can be supplied within a reactor volume 500 times smaller than that for a conventional furnace. A significantly lower wall surface temperature, supersonic gas velocities and a shorter primary gas path enable a controlled reduction in the residence time for chemical reactions, which optimises the yield. For the same reasons the conditions for coke deposition on the turbo-reactor surfaces are unfavourable, leading to an increase in plant availability. This study demonstrates that the mechanical work input into the feedstock can be dissipated through an intense turbulent mixing process which maintains an ideal and controlled pressure level for cracking.

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