مدل سازي رياضي جذب ديناميك و چندجزيي هيدروكربن هاي سبك در بستر ثابت كربن فعال

Mathematical Modeling of Dynamic Adsorption of Multi-Component Gaseous Hydrocarbons in Fixed Bed of Activated Carbon Particles

In the present artyle, the mathematical modeling of multi-component hydrocarbon adsorption in a fixed bed of granular activated carbons, with different shapes, was carried out numeryally. The model can predict the behavior of adsorption of hydrocarbon mixtures in the air flow, as a transient function of time and as a function of bed length and particle radius with respect to bed axial dispersion, external film resistance and pore diffusion mechanism inside the particle according to equilibrium adsorption isotherm of Extended Langmuir on the solid surface. This model can predict the breakthrough curves at different operational conditions of temperature, pressure, inlet concentrations, and flow velocity for adsorption and desorption cycles. Orthogonal Collocation and Implicit Finite Difference Method are respectively, implemented for numerical solution of PDEs in particles and packed bed, for the mixtures of ethane, propane, n-butane and n-pentane in air. To ensure from the accuracy of the model, hydrocarbon fractional uptake of the adsorbent was calculated by the model and was compared with experimental results found in by literature. The results show a good fitness of model and experiments. The sensitivity of analysis was studied by changing the model parameters such as particle size, tortuosity factor of adsorbent, gas flow rate and temperature. The results exhibit high dependency to the particle size and tortuosity factor. Also, the breakthrough curves of purging the bed by pure air flow was studied at different flow rate in order to predict the time of bed regeneration.