بررسي و مقايسه مدل هاي جذب سطحي براي فرآيند PSA در بسترهاي فشرده

چكيده انگليسي :

222The Study and Comparison of Surface Adsorption Models for PSA Process in Packed Beds Majid shahimohamadi majidshahimohamadi@yahoo com Date of Submission 26 August 2012 Department of Mechanics Isfahan University of Tecnology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Prof Mahmud Ashrafizaadeh Supervisor Mahmud@cc iut ac ir Abstract In pressure swing adsorption transmission flow from bed is influenced by the swing pressure until adsorptionprocess is performed in the first half time cycle and in high pressure by adsorbent particles and the rich output ofthe desirable component is produced In the second half time cycle system pressure is low and desorption process isdone by particles until the bed is dissented from saturation state and is made ready for adsorption process in a newhalf cycle This continues in multiple cycles producing further output This project addresses the simulation ofpressure swing adsorption for the separation of Oxygen from air by means of one packed bed in adsorption andblow down stages and two packed bed entire Skarstorm cycle pressurization adsorption blow down and purgestages using Comsol 4 2a software Adsorbent particles are of 5A zeolite type In this simulation in isothermalstate partial mass balance equations for flow components along with mid LDF relationship are solved andLangmuire equilibrium isotherm is employed for the expression of equilibrium concentration of components inintraparticles and interparticles Under these conditions based on the changes of flow components partial pressurein the direction of bed and time changes of Molecular and Knudsen diffusion coefficients diffusion coefficientswithin the macropores of adsorbent particles are computed Also the effect of employing surface diffusioncoefficient diffusion coefficients within the micropores of adsorbent particles is investigated Considering thevalues of these coefficients and tentative relationships we obtained the effect of changes of axial diffusioncoefficient and effective homogenies diffusion coefficient in correlation with LDF model for computing Nitrogenadsorption flux and components concentration inter particles In addition the effect of changes of flow viscosity which are due to changes of flow components mole fraction in the direction of bed and time on computingNitrogen s adsorption flux and components concentration inter particles is examined The results of this simulationare compared with those of process simulation in isothermal state and in states in which axial diffusion coefficient effective homogenies diffusion coefficient and flow viscosity are assumed to be independent of position in thedirection of bed and time Surface diffusion coefficient is also neglected The importance of this project lies inmore precision computation of Nitrogen s adsorption flux and components concentration inter particles ascompared with previous simulations in isothermal states Also in this project the first half time cycle of Skarstormcycle is simulated with the combination of orthogonal collocation and Finite volume methods using a computerprogram The subject model is the Fick model Equations employed here include partial mass balance equations forflow components within a bed partial mass balance equations for flow components within the adsorbent particle and energy balance equation within bed In this state changes of temperatures in the direction of bed and time areconsidered but changes of temperatures for adsorbent particles LiLsx zeolite type are assumed to be only in thedirection of time Keywords PSA process packed bed adsorbent particle micro and macropores Oxygen Nitrogen

شاهي محمدي، مجيد

بررسي و مقايسه مدل هاي جذب سطحي براي فرآيند PSA در بسترهاي فشرده

دانه جاذب , حفره هاي ماكرو و ميكرو , اكسيژن و نيتروژن