An analysis of gas hydrate dissociation in the presence of thermodynamic inhibitors

The kinetic behavior of small cylindrical methane hydrate samples as they dissociate in the presence of thermodynamic inhibitors is investigated experimentally and theoretically. A one-dimensional time-domain representation of the thermal processes involved allows a simulation of the experimental procedure while testing several kinetic and heat transfer dissociation models at the decomposing hydrate surface. Preliminary calculations with constant convective (liquid side) heat transfer coefficients show that the inclusion of an intrinsic dissociation kinetic model from the literature leads to a substantial mismatch between data and predictions. This apparent difficulty suggests that the intrinsic dissociation formalism may not be applicable to situations when hydrates are not decomposed by depressurization. A simpler equilibrium assumption for the interface temperature yields significantly better results. When the convective heat transfer coefficient is expressed as a simple power of the dissociating front velocity, up to a multiplicative factor, the agreement between data and calculations can be further improved. (C) 2009 Elsevier Ltd. All rights reserved.