Abstract: The computational fluid dynamics and discrete element method (CFD-DEM) and the porous medium model were used to numerically simulate a tubular fixed-bed reactor, and the packing characteristics and unit pressure drop of the column particle bed were compared. The consistency and efficiency of the two numerical simulation methods were compared. The calculation results showed that the column bed was more stable with mixed loading than with single loading. In the single loading and a certain tube diameter ratio, the pressure drop of bed increased with the increase of the inlet gas velocity when a single filling was used and the pipe diameter ratio was fixed. Therefore suitable inlet gas velocity should be selected in practical applications to prevent equipment damage. When the hybrid loading method was used, the bed cross-section pressure fluctuation was significantly reduced by 20.63%, and the bed particle accumulation was more uniform. Comparing the calculation results and efficiency of CFD-DEM with that of porous media model, it was found that when the particle Reyno number (Re_p) was less than 229, the maximum deviation of bed pressure drop between the porous media model and the coupling algorithm was 6.3%; when the Re_p increased from 229 to 458, the deviation of bed pressure drop increased with the increase of Re_p, and the maximum deviation was 13.4%, which met the requirement of engineering accuracy. In terms of computational efficiency, the calculation time of porous media model is 1/320 of that of CFD-DEM coupling algorithm. Therefore, the porous media model has better applicability and reliability for the calculation of columnar granular beds when the pipe diameter ratio is greater than 16.58 and Rep is less than 458.

Key words: columnar particles, tubular fixed bed reactor, CFD-DEM coupling method, porous media model, pressure drop, numerical simulation, pipe diameter ratio