Integrated reactor analysis of an externally heated multitubular reactor for carbon dioxide-assisted oxidative dehydrogenation of propane

초록

Carbon dioxide-assisted oxidative dehydrogenation of propane offers a route to propylene production and carbon dioxide utilization, but its strong endothermicity makes reactor performance highly sensitive to heat-supply distribution. This study addresses the lack of an integrated strategy linking experimentally fitted kinetics, rapid operating-condition screening, and geometry-resolved evaluation of shell-side flow and heat transfer nonuniformity. The hypothesis was that pronounced local flow and thermal non-uniformities could develop in an externally heated multitubular reactor while causing only limited variation in integrated tube-outlet performance. A seven-reaction kinetic model was fitted to experimental data and examined using 200 case-wise bootstrap resamples and local sensitivity analysis of 16 kinetic parameters. Subsequently, a one-dimensional non-isothermal model generated a constrained Pareto set, and a three-dimensional model assessed the selected condition. The fitted model reproduced experimental trends with Pearson correlation coefficients of 0.938-0.982; the selected one-dimensional solution gave 66.12% carbon dioxide conversion, 79.74% propylene yield, and 72.29% carbon dioxide utilization efficiency, whereas the three-dimensional assessment gave 65.27%, 82.06%, and 72.71%, respectively; despite a heat transfer-coefficient non-uniformity index of 55.56% and a maximum tube-to-tube catalyst-temperature difference of 15.58 K, the maximum tube-to-tube differences were only 0.17 percentage points for carbon dioxide conversion and 0.97 percentage points for propylene yield. These results demonstrate that pronounced local thermal heterogeneity can coexist with limited tube-to-tube performance variation and that sequential reduced-order optimization followed by geometry-resolved assessment provides an efficient design strategy for externally heated multitubular reactors.

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