Sequestration of Carbon Dioxide Using Aqueous Ammonia in A Stirred-Tank Scrubber--A Study of Absorption of Carbon Dioxide And Crystallization Kinetics of Ammonia Bicarbonate

摘要

A pH-stat continuous-stirred-tank scrubber for capturing carbon dioxide using aqueous ammonia was used to explore the effects of process variables on the absorption of carbon dioxide and crystallization kinetics of ammonia bicarbonate. Overall mass-transfer coefficients and crystallization kinetics were determined by means of mass balance and population balance model at a steady-state condition, respectively. The results showed that mass-transfer coefficients were in the range of 0.023-0.112 1/s, depending on the operating conditions. Solids were characterized by EA, XRD and FTIR, all indicating ammonia bicarbonate crystals. From measured particle size distribution, the nucleation rate,agglomeration kernel, and volumetric growth rate could be determined by using moment analysis. Correlation of overall mass-transfer coefficient with variables showed that gas-flow rate and specific power input were dominate factors, while liquid-flow rate and slurry density were minor factors. A correlation for kinetic expression showed that agglomeration kernel was nearly independent of nucleation rate and mean resident time, while agglomeration kernel was proportional to the orders of 0.36, -0.78, and 0.61 for volumetric growth rate, slurry density,and specific power input, respectively.