Removal of carbondioxide from flue gas by absorption

The objective of this study was to reduce the amount of emission by using the absorption method of carbondioxide, which has a large contribution to global warming. For this purpose, packed and bubble column reactors and different solvents were used. In the first part of the study Box-Behnken experimental design Response Surface Methodology (RSM) was applied in a bubble column reactor with a semi-batch system. In an experimental study that using RSM, monoethanolamine (MEA) was used as solvent and optimization was performed for different MEA concentration, gas flow rate, diffuser pore diamete rand temperature parameters. As a result of the study, 119 g CO2 / kg MEA absorption capacity was obtained under 5 L / min gas flow rate, 30% solvent concentration, 1.5 mm diffuser pore diameter and 30oC temperature conditions. According to the model result, while the absorption capacity increases as the temperature decreases and the solvent concentration increases, it is not significantly affected by the gas flow rate and the diffuser pore diameter. In the second part of the study, experiments were carried out by using counter current flow regime in the bubble column reactors and different solvents (MEA, NaOH, KOH, MgOH2). In the study, the effect of solvent concentration, gas flow rate, liquid flow rate, initial CO2 concentration for different solvents were investigated. As a result of the study, it was observed that Mg(OH)2 was not effective in CO2 removal, while KOH, NaOH and MEA were effective. 50.000 ppm initial CO2 concentration was reduced with 78% removal efficiency under the conditions of 2.5 L / min gas flow rate, 500 mL / min NaOH liquid flow rate and 0.25 M NaOH concentration. 0,369 mol CO2 / mol NaOH Absorption capacity, 0,19x103mol / Ls absorption rate and 1.55 1/min mass transfer coefficient were obtained. In the third part of the study, absorption of CO2 with MEA and NaOH solvents in the packed column reactor was investigated. The absorption column was filled with Raschig rings and glass spheres, and experiments were carried out by the counter current flow regime of gas and liquid, and the effects of the filling packing materials on the CO2 removal were determined. In the study, performance of packed column was determined by using different solvent concentration, liquid flow rate and gas flow rate. In the glass-filled column, 50.000 ppm initial CO2 concentration was reduced with 94% removal efficiency under the conditions of 2.5 L / min gas flow rate, 500 mL / min. Under the same conditions, the CO2 removal efficiency of the column filled with Raschig ring was 90.4% and 5.99 1 / min mass transfer coefficient, 0.038 mol CO2 / mol NaOH absorption capacity, 0.159 x103 mol / L.s absorption rate were obtained. In the last part of the study, MEA, PZ and NMP solvents and mixtures were used in the column by counter-current flow filled with rashing rings. In the experiments; The highest CO2 removal efficiency is achieved with 57.5% and the 2.178 1 / min highest mass transfer coefficient with an amine mixture of 0.03 MEA / 0.07 PZ amine, while the 0.217 mol CO2 / mol solvent highest absorption capacity was obtained with 0.05M PZ solvent. The highest 0.265 (103mol / Ls) absorption rate was obtained with 0.1 M PZ. As a result of this thesis, it has been observed that flue gas containing 50.000 ppm CO2 can be successfully removed in bubble column reactor and packed column reactor. Keywords: CO2 absorption, packed bed and bubble column, amine solvents, alkali solvents, glass spheres, Raschig ring