(321e) Development of a Novel Carbonate Absorption Process with Crystallization-Enabled High Pressure Stripping for Post-Combustion CO2 Capture: Kinetic Study of Bicarbonate Salt Crystallization

Development of a Novel Carbonate
Absorption Process with Crystallization-Enabled High Pressure Stripping for Post-Combustion
CO₂ Capture: Kinetic
Study of Bicarbonate Salt Crystallization

Qing
Ye^1,2, Manoranjan Sahu², Yongqi Lu² and Xinlei
Wang¹

1
Agricultural and Biological Engineering, University of Illinois at
Urbana-Champaign

2
Illinois State Geological Survey, University of Illinois at Urbana-Champaign

A novel absorption process with high
pressure stripping is being developed at our group for the post-combustion CO₂
capture application. The process employs a carbonate salt aqueous solution,
such as potassium carbonate (PC), as a solvent. The CO₂ absorption
operates at elevated temperature and the bicarbonate in the CO₂ rich
solution from the absorber is crystalized in a separate cooling-crystallizer.
Slurry of bicarbonate crystals is used in the stripper for CO₂ stripping
at high pressure. Compared to conventional mono-ethanol-amine (MEA) processes,
the carbonate-based process consumes less stripping heat and CO₂
compression work. A preliminary techno-economic analysis reveals that the
energy use of the novel process is 40-50% less than that of its MEA
counterpart.

Crystallization of the bicarbonate from the CO₂-rich
PC solution is a key step in the carbonate-based process. Kinetic studies of
the bicarbonate crystallization were performed under continuous mix suspension,
mixed product removal (MSMPR) mode using an automated calorimetric reactor
system. Parametric tests were conducted to investigate the effect of the PC
concentration, CO₂ loading, addition of absorption promoter,
temperature, residence time, stirring speed, seeding, etc. on the kinetics of the
crystallization and morphology of crystal products. Crystal solids were
characterized by particle size distribution (PSD), turbidity, SEM, and XRD
analysis techniques. Kinetic data, such as the nucleation rate constant, size-dependent
growth rate constant, and agglomeration/breakage factor, were obtained by fitting
the differential PSD data under various operating conditions.

This presentation will provide a summary of the
results from the crystallization kinetic study and discuss their implications
for the crystallizer design.