Taking into consideration mounting greenhouse gas emissions due to global industrialization, it is imperative from an environmental stand point that new developments be made in emissions reduction CO2 capture. This thesis provides an investigation of one such potential development in the process of solvent absorption to treat the flue gases produced from power-plants and other heavy industries.
The purpose of this thesis is to investigate the novel concept of pH swing in the conventional solvent absorption process. It has been proposed that by introducing a pH control agent to the system to alter the pH, it may be possible to reduce the energy requirement in CO2 recovery. This potential is significant based on the fact that the reduction in energy translates to monetary savings, making the process more attractive for industries.
The theory was tested through experimentation in the lab on a bench scale using the chemical solvent Monoethanolamine and the pH control agents; Suberic acid and Phthalic acid. Evaluation of the theory was made through direct comparison of with and without the addition of an acid, on the basis of energy efficient performance. The experimental variables controlled were the concentration of the solvent, the type of control agent and the concentration of the control agent. The energy efficiency was determined from the volume of CO2 recovered and the energy consumed in the process.
Experimental results showed that the addition of Suberic acid and Phthalic acid to the solvent absorption process respectively produced an increase in CO2 recovered and a decrease in the energy consumed by the system. Variance in acid concentration showed that the energy efficiency increased significantly by lowering the pH in an inversely proportional relationship. In terms of performance of the two acids, Suberic acid appeared to out perform Phthalic and produced the greatest energy efficiency increase of 1400% through a pH drop from 9-8.