Abstract :
[en] The anthropogenic emission of greenhouse gases to the earth’s atmosphere has been recognized in the past few decades as a source of potential threat to the environment due to its contribution in greenhouse effects (trapping the sun’s radiation in the earth’s atmosphere and causing global warming). Roughly, over 60 % of global warming impacts are relevant to the emission of carbon dioxide to the atmosphere. Carbon dioxide is emitting to the atmosphere from the combustion of fossil fuels (coal, natural gas, and oil), transportation, solid waste, or from industrial processes (e.g., manufacture of cement, steel, limestone or glass). In this study, adsorption process relying on solid adsorbent is proposed whereas vacuum pressure swing adsorption (VPSA) process is implemented to capture CO2 from flue gases. This process is easy of operation, high adsorption capacity, environmentally friendly, low operation cost, efficient recovery of the solute and lower energy requirements for the regeneration (lower than amine-based process 3800-4000 KJ/Kg CO2). Furthermore, VPSA is usually preferred as it has shorter cycles time than temperature swing adsorption (TSA) process due to lengthy cool down time of TSA beds. MOF MIL-160 (Al) is selected as an adsorbent because it exhibited: water stability, ultra-microporosity and potential interacting sites, good selectivity to capture CO2 from post and pre-combustion conditions. Aspen Adsorption software version 11 is used to handle the simulation and to generate the flowsheet. The Skarstrom cycle is used in this study to control the steps of the adsorption process. VPSA simulation performances are evaluated based on four different parameters: product recovery, product purity, unit productivity, and the total power consumption. The whole principle of simulation of such process is to vary the parameters of the various stages to find the combination which will give the best performances. It is however very regularly admitted that a system of two columns alone does not allow to reach very high performances. It is therefore often necessary to install at least two units in series. It was noticed that increasing the adsorption time led to an increase in CO2 purity and decreasing the CO2 recovery, and vice versa. On the other hand, increasing the purge time improved the CO2 recovery with decreasing the CO2 purity. The energy consumption was less than that of amin-based process in all simulations. In conclusion, the findings of this study are agreeable with the previous studies from literatures in terms of low system performances can be obtained by employing two-bed of VPSA process.
