EnBW's Post-Combustion Capture Pilot Plant at Heilbronn–Results of the First Year's Testing Programme

Abstract

The EnBW post-combustion capture pilot plant at Heilbronn in Germany was built in 2010 and commissioned in March 2011. The pilot plant is designed to capture 7.2 tons of CO2 per day from a flue gas slipstream taken downstream the FGD of the power plant. For the construction of the pilot plant a partitioned material concept has been realized applying both stainless steel and plastics. During a benchmark campaign with 30wt. % MEA it was found that the minimum specific reboiler duty is less than 3.4 GJ/t CO2 at a liquid-to-gas ratio of 2.7kg/kg and a capture rate of 90%. Solvent samples were analysed by titration and CO2 solvent loadings well above 0.5mol CO2/mol MEA were determined. This high CO2 loading is possibly due to good absorptions properties, such as the absorption height of 23.9 m, a low gas velocity of approx. 1 m/s in the absorber and low lean solvent and flue gas temperatures of 32 and 35°C. Solvent degradation in the pilot plant is clearly dominated by oxidative degradation forming formate and oxalate as major degradation products. Due to the application of the pre-scrubber the increase of inorganic salts is more or less continuous at a moderate level. Finally, a system for managing and maintaining solvent properties over long operational periods is developed and discussed.