International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 1244 ISSN 2229-5518 IJSER © 2014 http://www.ijser.org A simulation study on the removal of CO 2 and CH 4 lost from raw biogas in a packed bed absorption column Sharjeel Waqas, Muhammad Nawaz, Muhammad Usman Tahir, Ghulam Murtaza, Muhammad Jamil Abstract: A simulation study on the removal of CO2 and CH4 lost from raw biogas in a packed bed absorption column has been carried out to observe the effect of pressure and water flow rate. Biogas produced by the anaerobic digestion contains mainly CH 4 (55%-65%) and CO2 (35%-45%). CO2 is necessary to remove before its use as domestic fuel because it reduces the calorific value of the biogas. Pressure of the absorption column has been changed from 5 to 20 bar and absorption of CO2 varies from 49.9 to 97.99%. CH4 lost is also noted at these pressures which vary from .142 to 1.65%. Water flow rate is changed from 40 to 100 kg/hr and CO2 absorption varies from 49.9 to 84.14%. CO2 gas in the purified biogas should be less than 3% and CH 4 loss should be less than 1% for its use as replacement of fossil fuel. It is concluded from this research that water flow rate and pressure is directly proportional to the absorption of CO2 and percentage CH4 loss. Optimum conditions for the removal of are selected as 15 bar pressure of absorption column and 80 kg/hr water flow rate. Key Words: Absorption Column, Biogas, Carbon dioxide, Methane, Packed Bed ——————————  —————————— 1 Introduction Energy production from renewable sources has strategic importance for environmental production [1]. Biomass energy produced by biogas from the anaerobic digestion and in the presence of microorganisms can not only reduce the discharge kitchen waste and city sludge, it also plays an important role in the remission of greenhouse effect [2]. Biogas is traditionally used for energy production rural areas with low efficiency [3-4]. It is now used widely by value added way in which the raw gas is purified to natural gas quality [5-7]. Biogas produced by anaerobic digestion needs to be treated to become the energy of the future [8]. Carbon dioxide (CO 2 ) present in the raw biogas does not affect the combustion process but it decreases the energy content of the gas. ———————————————— • Sharjeel Waqas is currently working as lecturer in School of Chemical Engineering, The University of Faisalabad, Faisalabad, Pakistan, PH-+923454556266 Email: sharjeelengineer@gmail.com • Muhammad Nawaz is currently working as lecturer in School of Chemical Engineering, The University of Faisalabad, Faisalabad, Pakistan, PH-+923457895244 Email: muhammad.nawaz244@yahoo.com • Muhammad Usman Tahir is currently working as assistant professor in School of Chemical Engineering, The University of Faisalabad, Faisalabad, Pakistan, PH-+923009609252 Email: usmanengr1@gmail.com • Ghulam Murtaza is currently working as Lecturer in School of Chemical Engineering, The University of Faisalabad, Faisalabad, Pakistan, • PH-+923349778001 Email: murtazaengr@gmail.com • Muhammad Jamil is currently working as professor in School of Chemical Engineering, The University of Faisalabad, Faisalabad, Pakistan, PH-+923004382693 Email: professor_jamil@yahoo.com Biogas produced from biomass waste contains mainly methane (CH 4 ) (55%-65%) and CO 2 (35%-45%) [9]. Raw biogas has a calorific value of 22000-25000 kJ.m -3 , but this value can be increased up to 39000 kJ.m -3 by the removal of CO 2 [10]. Biogas after the removal of CO 2 has methane contents 96%, which are similar to natural gas. This purified biogas can be a replacement of fossil fuels [9]. CO 2 in the purified biogas should be less than 3% [11]. Purified biogas can be produced by absorption in organic amine solution or water, membrane separation, cryogenic distillation and pressure swing adsorption [12-14]. The production of purified biogas by absorption with organic amine solution is an efficient process. But the regeneration of the organic amine solution is highly energy consuming [15]. This method is also known as chemical absorption. Apart from using amine solution for purification, potassium hydroxide (KOH), sodium hydroxide (NaOH) and calcium hydroxide Ca(OH) 2 can also be used. Purification through membrane is not feasible because membrane is expansive and can easily be contaminated [16]. Cryogenic distillation is a method for separating CO 2 at low temperature. CO 2 is recovered as liquid product which can be transported easily [12]. Disadvantage of this process are low thermal efficiency and high capital cost [17]. Pressure swing adsorption does not involve equipment corrosion and environmental pollution. But frequent adsorption/desorption IJSER