Process intensification and environmental consideration of sodium bicarbonate production in an industrial soda ash bubble column reactor by CO2 recycling

Abstract

In the present study, a mathematical model is developed for a new configuration of sodium bicarbonate production in an industrial bubble column reactor. In the conventional configuration, the CO2outlet stream from the reactor is vented to the atmosphere while in the new configuration, a portion of the outlet CO2 stream is recycled and mixed with the inlet CO2flow of the reactor in order to reduce the greenhouse gas emission and also achieve a high purity level of the desired product. A gas sparger is installed at the bottom of the bubble column to provide a uniform gas flow distribution. A three−phase mass balance equation is considered. Liquid thermal behavior, gas pressure profile, CO2 conversion and mole fractions in the gas phase which mainly affect the production and size distribution of sodium bicarbonate crystals, are investigated. The results of the proposed model are compared with the conventional bubble column reactor (without recycle stream). The results show 314mol/m2.s CO2 saving and 50% increase in solid production as well as significantly reduction of air pollutants are also achieved with the new configuration. The optimized operating temperature for sodium bicarbonate production which was determined theoretically is reported to be 323K.