Modeling pilot plant results for CO2 capture by aqueous piperazine

Abstract

Abstract Concentrated aqueous piperazine has been proposed as a possible evolutionary step from monoethanolamine (MEA) as a solvent for post-combustion capture. High concentration piperazine (>5 m) has volatility similar to MEA but provides CO 2 absorption rate and capacity that is almost double that of 7 m MEA. It is also more resistant to oxidative and thermal degradation and can be used up to 150 °C. In order demonstrate these benefits a one month pilot plant campaign was conducted in November 2008 at The University of Texas at Austin with 5 m, 8 m and 9 m PZ. An absorber model for concentrated PZ was developed in Aspen Plus ® RateSep™. The model was validated with the pilot plant results and served to assess the quality of the pilot plant data using the reconciliation tool in Aspen Plus ® . The model simulates the temperature profile of the absorber. Loadings are matched within 0.03 and the deviation of the removal fraction is no more than 0.03. The absorber model was used to study intercooling and determine optimum conditions for its implementation. Based on pilot plant data and model results 90% CO 2 removal can be achieved with 8 m piperazine, 9 meters of packing, and intercooling with a loading shift from 0.32 (lean) to 0.39 (rich) mol CO 2 /mol alkalinity and steam heat rate in the stripper of 148 kJ/mol CO 2 and an equivalent work of 33.6 kJ/mol CO 2