Document Type: Research Article
Tarbiat Modares University
The main objective of this research was stability determination of activated carbon adsorbent at fixed bed adsorption column for desulfurization of diesel fuel by mathematical modeling. This model is based on mass balances. Equations that outcome from mass balances are known as second degree of partial differential equations, which must solve together simultaneously to generate an appropriate breakthrough curves at the end of the bed. On the other hand, running momentum balance using some assumptions, lead to Ergun equation which clearly represents pressure drop through adsorption bed. The mentioned equations were solved simultaneously in MATLAB software and the solution method was finite difference. After ensuring the validity of the model, scaling up is done to determine adsorbent stability and quantify its performance in an industrial dimension bed. Then the effective parameters on the bed operation and adsorbent stability were identified.
Also the batch adsorption isotherm experiments were carried out at room temperature to determine maximum capacity of adsorbent in sulfur compound adsorption. Using capped bottles containing 10 mL solutions which contain dibenzothiophen (DBT) dissolved in n-decane and 0.1 g of activated carbon that were equilibrated for 5 hours. Concentrations of Thiophenic Compound (TC) solutions were 330,462,660,990, and 1,320 mg/L of TC. The experiment method was according to some author’s studies.
The fluid velocity and mass transfer resistance for diffusion in adsorbent’s pores are the most important parameters in adsorption bed’s behavior and generating of breakthrough curves. The lowest the fluid velocity, the more time the fluid stay in bed and the bed's efficiency raises in terms of pollutant removal accordingly, as well as bed saturated in longer time.