A new apparatus to enhance the rate of gas hydrate formation: Application to capture of carbon dioxide

Abstract

A new apparatus employing a modular, mechanically agitated gas-inducing crystallizer is used to demonstrate the capture of CO 2 via hydrate crystallization. The crystallizer enhances the contact of hydrate forming gases with water and thus the rate of hydrate crystallization increases. Flue gas (CO 2/N 2) and fuel gas (CO 2/H 2) mixtures were used to represent post- and precombustion capture. A comparison between the rates of hydrate formation in different crystallizers is presented by defining a metric called the normalized rate of hydrate formation. The gas uptake and the separation efficiency for the fuel and flue gas mixtures were found to be greater compared to the results obtained in a smaller scale stirred tank reactor ( Kumar et al., 2009c; Linga et al., 2008). The gas uptake and CO 2 recovery for flue gas mixture in the presence of THF obtained in this work was higher than that reported in the literature with tetra- n-butyl ammonium bromide and tetra- n-butyl ammonium fluoride ( Fan et al., 2009; Li et al., 2009). Although hydrate crystallization is able to capture CO 2, the power required for mechanical agitation was found to be very significant. If the hydrate process is to be used industrially then hydrate crystallization must be carried out without mechanical agitation.