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Accelerated heat transfer in thermal cracking reactor tubes: the time for sinusoidal corrugated configuration

Mansouri Mogharab, A ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1007/s43153-022-00260-4
  3. Publisher: Springer Science and Business Media Deutschland GmbH , 2022
  4. Abstract:
  5. Olefin industry came to a commercialization maturity, but still energy consumption, coke formation and thermal cracking optimization seem hot debates. The typical use of static mixers or fins inside the pipes itself leads to significant pressure drop, leading to higher power consumption and lower selectivity of olefins production. Herein we propose an innovative approach, i.e., accelerated sinusoidal heat transfer through mixing at viscous sublayer pipe-fluid interface. CFD simulation by SOLIDWORKS, ANSYS FLUENT computer-aided computations visualized hydrodynamic wave effects on heat transfer in corrugated tube taking bare tubes as reference. The length and outside diameter of tube were taken as 50 cm and 1.0 cm to simulate the temperature profile, and Nusselt number (Nu) and friction factor (f) inside the tube as a function of Reynolds (Re). The corrugated tube reached coil outlet temperature (COT) in a shorter length compared to bare tube, where sinusoidal waves revealed significant effect on coke formation tracked experimentally. A bench scale quartz reactor was constructed in which propane with purity of 99.5 % was fed, and surprisingly very low coke was formed on the interior surface of the corrugated tube. Such a drastic reduction in coke amount and high heat transfer efficiency could be attributed to proper mixing in thinner viscous sublayer of the corrugated tube comparatively, because of heat transfer change from conduction in bare tube to convection in corrugated one, as reflected in CFD simulations. This combined theoretical–experimental approach unraveled that the use of corrugated tube not merely boost heat transfer across the tube walls to the fluid, but also drastically decreases the amount of coke formed, which enlightens future ahead of olefin industry. © 2022, The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química
  6. Keywords:
  7. CFD ; Coke formation ; Corrugated tube ; Heat transfer ; Thermal cracking
  8. Source: Brazilian Journal of Chemical Engineering ; 2022 ; 01046632 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s43153-022-00260-4