Modeling pilot plant results for CO2 stripping using piperazine in two stage flash

Abstract

Piperazine (PZ) has shown good potential for use as a solvent for CO 2 absorption in post-combustion carbon capture [1]. It has a high absorption rate [2], good capacity [3], and very good resistance to thermal and oxidative degradation [4]. Thermodynamic and kinetic models for PZ-CO 2-water have been developed in Aspen Plus® [5]. Pilot scale experiments were conducted on a 0.1 MW scale at the Separations Research Program at UT Austin to demonstrate the performance of concentrated (8 m) PZ using an intercooled absorber and a two-stage flash. This paper describes modeling and simulation of CO2 stripping from PZ using data from two pilot campaigns conducted in Winter and Fall 2011. Vapor liquid equilibrium equations and thermodynamic models for this system were validated using pilot plant data and found to satisfactorily represent the actual operating conditions. Rigorous reconciliation was done on Fall 2011 data using Aspen Plus® Data Fit. The only major systematic adjustments were found in the CO2 measurements, which required 1.2 to 6.9% increase to match the predicted model values. The best equivalent work was 45.5 kJ/mol CO2 in Winter 2011 and 36.6 kJ/mol CO2 in Fall 2011. The validated model predicted that the pilot plant stripper configuration should be able to achieve 32.6 kJ/mol at its optimum operating conditions. Major parameters that affected pilot plant performance were low values of rich loading and non-optimal operation of lean loading and cold rich bypass. Optimized values of operating conditions at 0.4 rich loading were identified as 0.31 lean ldg and 4% cold rich bypass flow. © 2013 The Author.