Empirical Design Method Of Industrial Carbon Dioxide-Mixed Solvent Absorbers with Axial Dispersion in Gas

Abstract

A revisited differential simulation method is used for the design of a packed column in which absorption accompanied by a reversible chemical reaction takes place. The method is based on integration of local rates of absorption along the column. The local rates of absorption are measured in a laboratory model contactor for various compositions of the gas and liquid phases under different hydrodynamic conditions characterized by the physical mass transfer coefficient in the liquid. An explicit formula correlating the data is given which facilitates the design calculations including possible axial mixing of the gas phase in the column. As the model contactor a mixed cell is used in which the interfacial area is well defined. By using an auxiliary surface stirrer the values of the physical mass transfer coefficient are extended up to the values encountered in packed absorbers. In experiments, carbon dioxide was absorbed into a solution of triethanolamine, diethanolamine, and an activator (1,6-diaminohexane, hmda) in the following range of experimental conditions: temperature 50-80 °C, partial pressure of carbon dioxide up to 700 kpa, liquid loading 0-40 (N m3 CCV/m3, activator concentration 1.6-3.38 wt %. The revisited method is used for simulated design of existing industrial scrubbers.

CO2 capture by aqueous solutions of glucosamine in a bubble column reactor

“…By contrast, tertiary amines do not react directly to the carbon dioxide in order to form carbamate. Generally, tertiary amines react more slowly to CO 2 than primary and secondary amines [7].…”

CO2 capture by pyrrolidine: Reaction mechanism and mass transfer

“…Generally, this kind of amine reacts slower than primary and secondary amines. 7 Conversely, the formation of bicarbonate is usually attributed to tertiary amines, but previous studies indicate that this reaction can also take place with primary and secondary amines. 8 Figure 1 shows the mechanism proposed by Park et al 10 for the chemical absorption of carbon dioxide in primary amines.…”

Carbon dioxide chemical absorption by solvents based on diamine and amines blend

“…15 On the basis of experimental results previously discussed is possible to conclude that the tertiary center (see Figure 1) has a low influence on the absorption rate because in the first part of experiments, solvents with tertiary centers (DMAPA and blend of amines) show a similar behavior than solvent based only in primary amine (AP). For this solvent the first part of the experiment consists on a slight decrease in carbon dioxide absorption rate with lower values than the other solvents.…”

“…This reaction has a lower reaction rate than corresponding one using primary and secondary amines with carbamate production as main reaction. 15 On the basis of experimental results previously discussed is possible to conclude that the tertiary center (see Figure 1) has a low influence on the absorption rate because in the first part of experiments, solvents with tertiary centers (DMAPA and blend of amines) show a similar behavior than solvent based only in primary amine (AP). This fact allows to suppose that for these solvents, the reaction mechanism when amine concentration is high, is mainly the production of carbamate (with primary centers, see Figure 1).…”