Effect of catalyst shape on pressure drop and liquid holdup in a pilot plant trickle bed reactor

An atmospheric experimental study was carried out to measure hydrodynamics (pressure drop and liquid holdup) in TBR. The current work aimed to investigate the influence of catalyst shape, gas flow rate, and liquid flow rate on hydrodynamics through different industrial catalyst beds that comprised spherical, cylindrical, trilobe, and quadrilobe. Air was used as a gas phase with an extensive range from 0.03 to 0.27 m/s, while water was used with a range from 0.004 to 0.016 m/s, within 0.14 m inside diameter of a cylindrical column and 2 m bed length through various packing beds. The measured data were compared with two model approaches (phenomenological and empirical approaches) to investigate the effect of catalyst shape, gas flow rate, and liquid flow rate on the pressure drop and liquid holdup. The phenomenological model developed based on a physical picture with no two-phase fitted parameters. Ergun coefficients for a single-phase fluid flow were implemented to represent the bed characteristics in the bed. Modified Ergun coefficients were determined for each bed and compared with universal Ergun coefficients (E-1* = 150 and E-2* = 1.75) and non-spherical universal coefficients (E-1* = 180 and E-2* = 1.8). The comparison for total data regardless the bed indicated a maximum deviation of +/- 56% with Ergun and non-spherical coefficients, while decreased to a negligible value of 7% with modified coefficients. The results revealed a significant impact for catalyst shape, gas flow rate, and liquid flow rate on the hydrodynamics. Furthermore, the comparison between the data and models showed the phenomenological model exhibited a better agreement than the empirical model with a mean relative error for the pressure drop of 31.81% and the liquid holdup of 10.36%.

Automated summary

An experimental study was conducted to investigate the hydrodynamics in TBR with different industrial catalyst beds of spherical, cylindrical, trilobe, and quadrilobe shapes. The results showed a significant impact of catalyst shape, gas flow rate, and liquid flow rate on the pressure drop and liquid holdup. The comparison between data and models demonstrated that the phenomenological model had a better agreement than the empirical model, with mean relative errors of 31.81% and 10.36% for pressure drop and liquid holdup, respectively.