Gas Hydrate Growth Model in a Semibatch Stirred Tank Reactor

Abstract

The gas hydrate growth model of Englezos et al. (Chem. Eng. Sci. 1987, 42, 2647) was modified based on a concentration driving force where the equilibrium concentration at the hydrate surface is determined at the surface pressure and temperature, with the latter varying between the bulk and three-phase equilibrium temperature depending on the rate of heat removal. In order to study hydrate growth kinetics, literature mole consumption rates and hydrate surface area obtained in a semibatch stirred tank reactor were used. The extraction of the intrinsic kinetic rate constant is intimately linked to the estimated hydrate surface area, which is difficult to accurately measure. Theoretical estimation of the surface area using a population balance is also problematic since it does not account for the inherent presence of foreign particles, of unknown quantity and size distribution, serving as nucleation sites. Finally, mole consumption rates in such experimental systems may be controlled by gas−liquid interphase mass transfer, suggesting that accurate interphase mass transfer coefficients are required for proper estimation of the intrinsic kinetic rate constant.