Abstract
Degradation is a major problem which poses lots of emission risk during chemical absorption process with amine solvents. Degradation occurs through irreversible side reactions with CO2 and other flue gas components, forming into products that cannot easily regenerate. The degradation products then react with amines to form thermally stable salts, which accumulate in the system over time. The problems associated with degradation include decreased plant equipment life, foaming, corrosion, high solution viscosity, and increased operating cost. Amines capture about 70 90% CO2 from commercial power stations. These high removal rates have many environmental impacts due to their degradation products. Researchers have therefore shown interest in characterising and quantifying atmospheric emissions of amines and their degradation products. In this study, 2-Amino-2-Methyl-1-Propanol (AMP) degradation reactions were included into a largescale capture plant model to evaluate the influence of process variables, the emissions of AMP and its degradation products. Steadystate simulations were performed using Aspen Plus® V8.4 software to provide a full assessment of the degradation products and their impact on the capture process. This assessment is important because it identifies and quantifies all pollutants emitted from the process plant. The results of the simulation indicate that AMP emissions are 3.04E+03mg/Nm3 of CO2 lean flue gas, while the quantity of AMP lost due to degradation was 37.88kg/s for the largescale capture plant. The results further showed that among the gases emitted, ammonia was highest, while acetone was the highest gas formed. In this study, 2-amino-2-methyl-1-propanol (AMP) degradation reactions were included into a largescale carbon dioxide (CO2) capture plant model to evaluate the influence of process variables, AMP emissions and its degradation products. Steadystate simulations were performed using Aspen Plus® V8.4 software to provide a full assessment of the degradation products and their impact on the largescale AMP capture process. The results of the equilibrium model developed in this study revealed that AMP emissions are 3.04E+03mg/Nm3 of CO2 lean flue gas, while the quantity of AMP lost due to degradation was 37.88kg/s for the largescale capture plant. More importantly, the emissions obtained from the PWOD and PWD are 7.80E+03 mg/Nm3 and 9.82E+03 mg/Nm3 of CO2 respectively.
 Keywords: oxidative degradation, 2amino2methyl1 propanol, emissions, modelling
Highlights
Degradation is a major problem which poses lots of emission risk during chemical absorption process with amine solvents
The temperature of the flue gas from the natural gas combined cycle (NGCC) is reduced in the blower and further reduction occurs in the direct contact cooler (DCC) so that the temperature of the flue gas is slightly close to atmospheric
Modelling and simulation of degradation products in Aspen Plus®: The degradation reactions of AMP are added into the Aspen Plus® model
Summary
AMP capture plant description: Fig. 1 shows a pictorial view of the flowsheet for the aqueous AMP based postcombustion CO2 capture (PCC) plant, which is the Aspen Plus® process simulation presented in this study. The AMP PCC plant uses a water washer in the first two stages of the column after the absorption of CO2 This is to enable further reduction in the temperature of the exit flue gas, to recover the concentration of AMP, and to prevent volatile solvent products in the treated gas to be released to the environment. This is very important since the temperature in and out of the absorber affects the levels of volatile compounds, and this reduces CO2. Preliminary design and operations data for the capture plant are presented in Tables 2 and 3
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