Process intensification :absorption and desorption of carbon dioxide from monoethanolamine solutions using Higee technology

Abstract

Process intensification (PI) technologies are challenging the traditional unit operations in a wide range of engineering processes. The Rotating Packed Bed (RPB) or the Higee is a compact mass transfer machine that could challenge the conventional absorption/desorption columns especially in the off-shore oil facilities where space and weight are of great importance. This counter-current mass transfer operation between the gas and the liquid phases occurs at high rotational speed and with a short residence time. The objective of the project was to test the capability of the mass transfer machine (RPB) in gas sweetening field. Therefore, a RPB pilot plant facility was modified then experimentally tested for the chemical absorption of 4 vol. % C02/Air mixture using different concentrations of aqueous ethanolamine solutions (30,55,75, and 100 wt. %) at different temperatures (20', and 40"C). The hydraulic capacity or the flooding behaviour of the machine was initially investigated and then compared with Sherwood correlation. In addition, Wallis method was approached to correlate the flooding data. The analysis of the carbon dioxide concentration in the liquid and gas samples was carried out by a gas chromatograph. Týe mass transfer studies were carried out to identify the effect of temperature, rotor speed, liquid flowrate, and concentration on the HTU. The percentage recovery of carbon dioxide was 98.6,92.8,88.4 and 44.4% for 100,75,55, and 30 wt% MEA solutions. In addition, the regeneration of the amine solution by steam was investigated at various (G/L) ratios and rotor speeds. It was observed the efficiency of the operation was highest when the ratio (kg steanVL solution) was greater than 0.4. Key Words: Rotating packed bed, process intensification, Higee, gas sweetening, MIEA, carbon dioxide, absorption, steam desorption, HTU.