Factors Affecting CO2 Absorption in Water Using a Gas Absorption Packed Column

Abstract

Population growth is directly associated with increase in energy demand. Amplification in industrial activity has led to a drastic escalation in greenhouse gas emissions causing global warming. The major gas involves carbon dioxide, accounting for 76% emitted from different industrial sectors. The oil and gas industry alone is responsible for 90% of these emissions. Removing CO2 is a vital process in the gas industry which must be undertaken. Carbon capture utilization and storage (CCUS) technologies have evolved through the years due to the necessity of the current world-wide shared goal, to attain net zero. Several combustion methods have been developed to capture CO2 during actual operations at fossil fuel power plants, at natural gas processing plants and at coal gasification plants. However, methods that are based on chemical and physical absorptions have been most widely used. One example is the gas absorption-based method which requires low energy consumption and has been proven to be cost-effective. Using certain water types, mixed with minute concentration of chemical solvent, it can readily absorb CO2. This approach will be used in the following research study to investigate gas absorption rate using different water samples that pass through a packed column, thereby enhancing the mass transfer of gas component. In this study, the gas absorption experiments were carried out using SOLTEQ gas absorption unit containing DN 80 packed column with glass Raschig rings and with an effective column height of 1000 mm (Figure 1). Under constant operating conditions, the temperature and pressure were set to 24°C and 2 bars, respectively, to investigate the impact of pH level and conductivity of various types of water on CO2 absorption at different gas flow rate. The statistical analysis indicates that TDS and conductivity have a stronger correlation with gas absorption (P=0.99) than pH (P=0.76). The average CO2 absorption of the three samples at different flow rates (e.g., 0.8, 1.3, and 2.2 LPM) ranged from 36.40 in sample 1 to 69.50 in sample 2 at flow rate 2.2 LPM. Overall, samples 2 and 3, neutral to base with pH value of 7.25 and 8, respectively, have a statistically significant negative correlation with average CO2 absorption, whereas the acidic (pH = 5.42) sample 1 has significant positive correlation between the two variables (R2 = 0.99). Overall, samples 2 and 3, which are neutral to base with pH values of 7.25 and 8, have a statistically significant negative correlation with average CO2 absorption. In contrast, the acidic (pH = 5.42) sample 1 has a significant positive correlation between the two variables (R2= 0.99). This study provides optimal operating conditions for the CO2 absorption process. However, additional research is required to investigate the effect of other physical and chemical properties of water on CO2 absorption.