Precipitating Characteristics of Potassium Bicarbonate Using Concentrated Potassium Carbonate Solvent for Carbon Dioxide Capture. Part 2: Crystal Growth

Abstract

Crystallization kinetics of potassium bicarbonate in the potassium carbonate (K 2 CO 3 )−potassium bicarbonate (KHCO 3 )−water (H 2 O) ternary solvent system were estimated using focused beam reflectance measurement (FBRM) in unseeded batch cooling experiments. Two groups of experiments including apparent K 2 CO 3 concentrations of 35 and 40 wt %, both with 0.4 loading, at different constant cooling rates were conducted. KHCO 3 was the only precipitate in the ternary system. The concentration of KHCO 3 measured by autotitration and chord length distribution collected from FBRM were used to estimate the parameters required for the primary nucleation, secondary nucleation, and growth rate models through mass balance, population balance using the method of moments, and least-squares minimization in MATLAB. The solubility of the ternary solvent system was successfully predicted using the regressed electrolyte nonrandom twoliquids (ENRTL) activity model in Aspen Plus. The crystallization of KHCO 3 was impacted by KHCO 3 supersaturation and K 2 CO 3 concentration. Primary nucleation was found to dominate the system including both homogeneous and heterogeneous nucleation, whereas secondary nucleation was inhibited to a great extent. The model developed was able to predict the average particle size within 20%, the results obtained from the model were consistent with the conclusion that primary nucleation dominates the K 2 CO 3 −KHCO 3 − H 2 O solvent system.

Assembly of Metal–Phenolic Networks on Water‐Soluble Substrates in Nonaqueous Media

“…A real‐time focused beam reflectance measurement (FBRM) technique was employed to assess the effect of solution aging time on the Fe III –TA particle growth and the coating time using population distribution measurements of generated Fe III –TA particles in the form of chord length. [ 53,54 ] As observed in Figure a,b, the MPN coating process was complete within 35 min when a solution aging time of 1 min was used, whereas a longer coating process of 55 min was observed when a longer solution aging time of 60 min was used. These results reflect the role of Fe II on the kinetics of MPN formation.…”

Process modifications for a hot potassium carbonate‐based CO2capture system: a comparative study

“…Secondly, MEA suffers oxidative and thermal degradations under the high temperature associated with typical post‐combustion capture conditions. This requires frequent replenishment of the solvent with a fresh solution, thereby increasing the quantity of solvent usage and cost . Finally, the high carbon footprint associated with the mass production of this solvent makes it unattractive for large‐scale applications in post‐combustion capture processes .…”

“…This requires frequent replenishment of the solvent with a fresh solution, thereby increasing the quantity of solvent usage and cost. [17][18][19][20][21] Finally, the high carbon footprint associated with the mass production of this solvent makes it unattractive for large-scale applications in post-combustion capture processes. 22 For these reasons, a significant amount of research is being directed towards two main areas: developing lower cost and more environmentally friendly solvents, and designing various process modifications to minimise the energy penalties.…”