بررسي تاثير فشار ورودي در پديده جذب مخلوط چند جزئي گاز در بسترهاي فشرده

چكيده انگليسي :

Study of Inlet Pressure Effects on the Adsorption Phenomenon of Multicomponent Gas Mixtures in Packed Beds Hadi Zahab Saniei h zahabsaniei@me iut ac ir Mar th Department of Mechanical Engineering Isfahan University of Technology Isfahan Iran Degree M Sc Language Farsi Supervisor M Ashrafizaadeh Assist Prof mahmud@cc iut ac ir Abstract These days there are a lot of applications for pure gases in industries and medicines and with respect to increasing application of these gases there are various methods for gas purification One of the methods is the Pressure Swing Adsorption PSA In this project the objective is to numerically investigate the effects of the inlet pressure on the adsorption process Studying the adsorption in a packed bed is the first step in simulating the PSA process Adsorption is the dominant phenomenon in the gas purification using the PSA process The adsorption process usually occurs on the adsorbents which are called zeolites Under high pressures depending on the type of the adsorbent one of the multicomponent gas species is adsorbed more than other ones For separating gas mixtures many granular adsorbents are usually placed in a cylinder packed bed The main difference between the present study and previous ones is that in this study porous media approach has not been used for the simulation of the adsorption phenomenon in multicomponent gases mixture separation Therefore to numerically simulate the process the space among the adsorbents has been meshed with unstructured elements The Linear Driving Force LDF has been used for the adsorption simulation The governing equations are continuity momentum and nitrogen transport scalar equations which are solved in three dimensions To study the pressure variation effects on the adsorption process the pressure has been changed on the inlet The inlet gas is air which consists of nitrogen and oxygen mole fraction The FLUENT commercial software has been used for the simulations Air has been considered as an ideal gas and the adsorption process has been assumed to be isothermal A constant adsorption coefficient is assumed throughout the bed and nitrogen is assumed to be the only adsorbate of the flow Langmuir has been considered as the adsorption isotherm The discrete element method DEM algorithm has been used for constructing the packed bed The number of adsorbents in the packed bed is At the beginning of the process the adsorption rate is high because of the low amount of adsorbed nitrogen and as time passes amount of adsorbed nitrogen becomes more and more which causes the adsorption rate to decrease and finally approaches zero So most of the adsorption phenomenon happens in a short period of time The convection mechanism causes mass fraction to distribute throughout the bed and affects the adsorption process At the beginning the mass flux is high because of high adsorption rate As the adsorption rate decreases it leads the mass flux to reduce The pressure drops linearly along the bed By rising pressure the amount of adsorption and also the mass flux increases and the velocity decreases It is also found that the effect of adsorption on the pressure drop is low Key Words packed bed adsorption LDF model PSA PDF created with pdfFactory trial version www pdffactory com

ذهب صنيعي، هادي

بررسي تاثير فشار ورودي در پديده جذب مخلوط چند جزئي گاز در بسترهاي فشرده

PSA , جذب سطحي , مدل LDF