Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA

Gas absorbers are used to remove contaminants from gas streams. Multiple designs are used to accomplish this objective¹. A packed bed column uses gas and liquid streams running counter to each other in a column packed with loose packing materials, such as ceramics, metals, and plastics, or structured packing¹. The packed bed uses surface area created by the packing to create a maximum amount of efficient contact between the two phases¹. The systems are low maintenance and can handle corrosive materials with high mass transfer rates¹. Spray columns are another type of absorber, which uses constant direct contact between the two phases, with gas moving up and liquid being sprayed down into the gas flow¹. This system only has one stage and poor mass transfer rates, but is very effective for solutes with high liquid solubility¹.

The goal of this experiment is to determine how variables including gas flow rate, water flow rate, and carbon dioxide concentration affect the overall mass transfer coefficient in a gas absorber. Understanding how these parameters affect CO₂ removal enables contaminant removal to be optimized. The experiment uses a randomly packed water counter-flow gas absorption column. Eight runs with two different gas flow rates, liquid flow rates, and CO₂ concentrations were used. During each run, the partial pressures were taken from the bottom, middle, and top of the column unit, and the equilibrium partial pressures were calculated. These pressures were then used to find the mass transfer coefficient, and the mass transfer coefficients were compared to theoretical values.

The experiment uses a randomly packed water counter-flow gas absorption column. The column is packed with 34 cm of 13 mm berl saddles with 465 m²/m³ surface (effective) area. The pressure entering the system is about 1.42 bar with a temperature of about 26 °C, and valves at the entrance and exit of the column allow gas to escape. An "Oxy Baby" Infra-red spectrometer, directly connected to the unit at various locations, measures gas composition, and tanks of pur

Partial pressures were taken from each trial run. Mass transfer coefficients were calculated from these and compared to predicted values (Figure 2). The predicted values arise from the calculated operating line for the absorber (see reference 2 for an in-depth discussion of the operating line). Solid lines represent the values calculated using the operating line, while triangles represent the experimental mass transfer coefficient values. Confidence intervals

The goal of this experiment was to use factors of gas flow rate, water flow rate, and carbon dioxide concentration to determine the overall mass transfer coefficient in a gas absorber. The experiment used a randomly packed GUNT CE 400 water counter-flow gas absorption column. Eight runs with two different gas flow rates, liquid flow rates, and CO2 concentrations were performed. Partial pressures were taken from the bottom, middle, and top of the column unit, and these pressures were then used to find the mass transfer co

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