Numerical study of gas-phase pyrolysis reaction with turbulent flow in helically coiled tubes

Abstract

It is challenging to design a reasonable spiral tube reactor for gas-phase pyrolysis reaction because of the coupling effect of secondary flow and volume expansion. In this paper, two mathematical models are conducted. The three-dimensional (3D) detail model is used to study the effects of volume expansion and thermophysical properties changes on the gas-dynamics, heat transfer, and reactor performance; the one-dimensional (1D) simplified model is developed for designing industrial reactors. The pyrolysis process of isobutyric anhydride (IBAN) is selected as the representative model reaction. The 3D model’s results indicate that the decrease in density significantly increased both axial and radial velocities. The increase of axial velocity increases the pressure drop and decreases the IBAN conversion. The temperature distribution is unaffected by the changes in density and thermophysical properties. Moreover, axial distribution calculated by 1D simplified model are quite consistent with that of the 3D model, indicating that the proposed 1D model can be used to design industrial reactor accurately and efficiently.