Modelling of an annular photocatalytic reactor

Abstract

This work deals with the photocatalytic oxidation of toluene at room temperature and atmospheric pressure in the gas phase. The differential equations of the reactor model are solved numerically with simultaneous estimation of the model parameters. Estimation of the kinetic data is performed using a modified differential method of data analysis and a Nelder-Mead method of nonlinear optimization for parameter estimation. The reaction is performed in an annular photoreactor using UVA black light blue fluorescent lamp. The experiments are carried out at different total flow rates of the reaction feed (20-160 cm 3 min -1 ), two different inlet concentrations of toluene (2.67 and 5.24 g m -3 ) and at constant relative humidity (25%). A good agreement between the experimental data and theoretical predictions is obtained, supporting the applicability of the proposed models to describe the investigated process performed in laboratory annular photoreactor. List of symbols aGeometric surface area (m 2 ) A R Surface area of reactor (annulus) cross-section (m 2 ) C A Toluene concentration (g m -3 ) C A,0 Inlet toluene concentration (g m -3 ) C A,g Toluene concentration in the fluid phase (g m -3 ) C A,s Toluene concentration at the solid phase (g m -3 ) Average toluene concentration in the fluid phase (g m -3 ) D A Molecular diffusion coefficient of toluene in air (m 2 s -1 ) k A Reaction rate constant (min -1 ) k g Interphase mass transfer coefficient (m h -1 ) N Number of the experimental points (dimensionless) rRadial reactor coordinate (m) r A Reaction rate (mol h -1 kg -1 ) R Diameter of reactor annulus (m) SD Root of the mean square deviation (dimensionless) uSuperficial fluid velocity (m h -1 ) u m Mean superficial fluid velocity (m h -1 ) v 0Volume flow rate (m 3 h -1 ) V Reactor volume (m 3 ) X A Toluene conversion (dimensionless) zAxial reactor coordinate (m) Z Length of the reactor (m)Greek letters j Ratio of inner and outer reactor diameter (dimensionless) s Space time (min) Dimensionless parametersRe Reynolds number (dimensionless) Sc Schmidt number (dimensionless) Sh Sherwood number (dimensionless)