Effect of Placement of Packing Material Against Gravity on the Effective Wetting Area and Gas Absorption Efficiency of Absorption Equipment Packed with Glass Fiber Filter

Effective wetting area between the gas and the absorbent can enhance the efficiency of gas absorption. In this study, new gas absorption equipment packed with a flat glass fiber filter was developed, and the prevention of liquid stagnation due to gravity and liquid channeling in the glass fiber filter was demonstrated. As a result, the effective wetting area of this equipment was measured to be between 50,000 and 110,000 m2·m−3 when the flow rate of gas was controlled between 0.015 and 0.063 m3·(m3‒filter unit)−1·s−1 and flow rate of liquid was controlled between 0.78×10−4 and 3.1×10−4 m3·(m3‒filter unit)−1·s−1, respectively. To evaluate the effect of a large effective wetting area on gas absorption performance, we selected two topical systems: 100% of carbon dioxide (CO2) absorption into potassium hydroxide aqueous solution for CO2 utilization in agriculture and NOx elimination from exhaust gas derived from power plants. When the packing height of this equipment was 0.825 m, 99.7% removal efficiency of carbon dioxide (with 12 vol% of inlet concentration) was achieved, and the concentration of CO2 (0.03 vol%) at the outlet was less than the concentration in the atmosphere (about 0.04 vol%). However, the removal efficiency of nitrogen dioxide was not so high (64‒78%). This was because the nitrous acid produced by the absorption of nitrogen dioxide into water would contribute to the desorption of nitrogen monoxide.