Comparative energy and environmental performance of 40 % and 30 % monoethanolamine at PACT pilot plant

Abstract

Post combustion CO2 capture using amines is one of the most well understood processes. The most widely used and studied solvent for this purpose is 30 % Monoethanolamine (MEA). The main issue with the process is the use of energy for stripping CO2 out of the solvent. It is anticipated that higher concentrations of MEA can capture a higher amount of CO2 and thus reduce energy consumption but may also result in a worsening of the environmental emissions due to potential increase in corrosion and solvent degradation.In order to study the impact of 40 % MEA (as opposed to 30 % MEA) on the capture plant performance, a test campaign was carried out at the Pilot Scale Advanced Capture Technology (PACT) facilities of the UK Carbon Capture and Storage Research Centre (UKCCSRC) using 30 % and 40 % MEA. The absorber (9 m height ×0.3 m dia.) is packed with 28 sections (6.5 m) of Mellapak CC3 structured packing. The absorption column temperature profile is measured by 10 RTDs installed around 48 cm apart along the column length. The performance of the capture plant in terms of reboiler duty, capture efficiency, loading capacity and liquid to gas ratio is evaluated at different operating conditions.It has been found that specific reboiler duty using 40 % MEA drops by up to 14 % as compared to that with 30 % MEA under similar test conditions. It has also been observed that the process is very sensitive to reboiler temperature and slight changes in reboiler temperature can have a significant impact on the plant performance. Moreover, similar energy and capture performance can be achieved at different reboiler temperatures with right combination of temperature and pressure in the reboiler/stripper. Corrosion rate was found to be higher with 40 % MEA than 30 % MEA. Solvent degradation rate and solvent carry over has also indicated slightly higher levels for 40 %. Water wash was shown to be effective in recovering most of the MEA from the flue gas.