Experimental study on CO_2 capture from simulated flue gas by using aqueous ammonia with external magnetic field

摘要

A new ammonia-based CO_2 capture process is proposed in the paper. The process uses magnetically gas-solid-liquid bed as the reactor in which nano-ferromagnetic particles suspend in aqueous ammonia solution under the influence of external magnetic field (EMF). A continuous of CO_2 passes through the reactor, absorbed by aqueous ammonia. Experiments in a laboratory-scale apparatus were carried out to investigate the roles of the ferromagnetic particles and the applied magnetic field in CO_2 absorption. Results shows that EMF and nanoparticles (such as Fe_3O_4) can significantly improve the performance of CO_2 absorption. The highest CO_2 absorption efficiency with EMF and nanoparticles reaches 99.40%, more than 7% compared to that without EMF and nanoparticles. With EMF and nanoparticles, the CO_2 absorption efficiency increase significantly when using low concentration aqueous ammonia (5%~8%), large flux of simulated flue gas (3.5 L/min) and low absorption temperature (22-36°C). The promoting mechanism of EMF and nano-Fe_3O_4 on CO_2 absorption may be the enhancements of contact efficiency and mass transfer among gas-liquid-solid three phases, as well as the change of thermo-physical property of aqueous ammonia leading to the increase of the solubility of aqueous ammonia and the decrease of ammonia slip.