(156a) Process Intensification in Post-Combustion Carbon Capture

Post-combustion carbon capture via solvent absorption has been executed in several industrial-scale projects in recent years. However, prohibitive capital and operating costs have hindered the realization of many projects under development. Furthermore, there are concerns over the emissions of solvents and other pollutants, particularly for carbon capture plants built near residential areas. While process licensors bear a big responsibility to resolve these issues with enhanced solvents and process configurations, better mass transfer technologies and column designs can also contribute to this process intensification activity.

The duty of the flue gas blower upstream of the CO₂ absorber contributes the third highest operating expense in the carbon capture plant, after the CO₂ stripper reboiler and the CO₂ compressor system. Minimizing the CO₂ absorber column pressure drop helps to reduce the blower duty, and can be accomplished by the MellapakCC^TM structured packing, which offers lower packing pressure drop without sacrificing CO₂ absorption efficiency.

Solvent emissions are often reduced to sub-ppm levels by using two pumparounds in the water wash section of the CO₂ absorber. A more efficient column design could be achieved by replacing one pumparound with a once-through design, which firstly saves one set of pumps and heat exchangers, and secondly leads to near-zero emissions. The once-through design results in ultra-low specific liquid loads, requiring the use of a specialized structured packing with an ultra-low liquid load distributor.

Experimental results from both pilot and industrial columns will be presented to validate the efficiency and hydraulic performance of the mass transfer technologies discussed.