Enhancement of CO2 removal from flue gas in an oscillatory baffled column using potassium carbonate solution

Abstract

One of the efficient methods for reducing CO₂ emissions from flue gas streams in oil refineries and power plants is the CO₂absorption process using alkali solution. Potassium carbonate (K₂CO₃) solution, as CO₂ absorbent, was used in the present study due to its high CO₂ absorption capacity. However, K₂CO₃ has a drawback which is represented by its slow reaction with CO₂. To overcome this issue, an oscillatory baffled column (OBC) was utilized as a contactor to maintain a high degree of mixing in the CO₂ absorption system and thereby increasing the reaction rate between K₂CO₃ and CO₂ as well as enhancing the mass transfer rate. In this study the effect of different operation conditions of the process namely; inlet flue gas flow rate (15 % (v/v) CO₂ balanced with N₂) and oscillation conditions on CO₂ absorption in a semi-batch OBC were investigated. The experiments were performed with range of modified Reynolds Number of Oscillation (${Re}_o^{\prime }$ = 0⎼1450) and aeration rates (0⎼1 vvm) using K₂CO₃ (100 g/L, 0.72 M)0.1.8–3.5-fold of enhancement of CO₂ absorption rates was achieved by using OBC with respect to that obtained by baffled column (BC) (only baffles without oscillation) and plane bubble column (PBC) (without baffles and oscillation), respectively.

The use of K₂CO₃ as a solvent in an oscillating reactor (OBR) to remove CO₂ represents a new method due to the high reactivity of K₂CO₃ with CO₂, forming stable bicarbonate and carbonate compounds. OBR's enhanced mixing capabilities improve mass transfer rates and reaction efficiency, allowing for more effective CO₂ capture compared to conventional reactors. This combination leverages the strengths of both the chemical reactivity of K₂CO₃ and the mechanical benefits of OBR, potentially leading to more efficient and scalable CO₂ removal processes.