Mathematical modelling of CO2 capture from industrial flue gas by absorption into amine solutions such as monoethanolamine (MEA) has been undertaken for decades and steady state, rate-based and dynamic models have been constructed to predict the changes in the process. Recently, dynamic models have been used to predict the effect that physical operational changes have on the absorption process. As more is learnt about the chemistry of MEA and CO2 it becomes evident that the absorption system is losing available MEA, by degradation and by vaporization into the gaseous phase. This paper describes a dynamic model of the absorber column that can be used to predict the reduction of available MEA, the loss of MEA to the atmosphere, and the build-up of heat stable salts. The proposed mathematical model consists of a system of partial differential equations to represent the change of each component with height of the column and with time. It has been validated with data from a pilot capture plant located at the brown coal fired Loy Yang power station in Australia.
Fossil fuels are used widely for energy production and are likely to continue to play a major role world wide for many years to come. Much work has been done on the technology for capturing CO2 from gaseous industrial effluent. For large-scale applications like coal or natural gas-fired power plants, using amine solvents to capture post-combustion CO2 is the most mature CO2 capture technology. This technique can be used to retrofit existing plants by treating the flue gas after combustion. This paper details a dynamic mathematical model for the absorber column constructed from first principles. The loss of MEA through oxidative degradation has been quantified here for the first time and this is currently not possible using commercial packages. Reaction rate kinetics have been employed to predict the accumulation of oxidation products which is limited by the incomplete knowledge of the dominant reactions between O2 and MEA. When research has produced more detailed information about the products formed during this oxidation, it can be inserted easily into the model. Validation has been performed using data from the CSIRO PCC pilot plant at AGL Loy Yang. A limited parametric study of the impact of operating conditions on oxidation was performed.