Experimental and theoretical study of diffusion combustion of methane above a gas hydrate layer in a laminar air flow

The fraction of methane in gas hydrates is approximately 12 wt.%. Theoretically, the temperature of combustion of such a composition is rather low. Nevertheless, the measurements show that an appropriate organization of the process may ensure a much higher flame temperature. For this purpose, it is necessary to separate the regions of dissociation and combustion (i.e., eliminate water heating). On the other hand, for combustion to be stable, some part of the combustion heat should be returned to the hydrate region to maintain the dissociation rate at a needed level. Stability of methane hydrate combustion is naturally determined by the ratio of heat release and heat transfer. The present paper described experiments on methane combustion above a layer of a dissociating gas hydrate, and a simple mathematical model is proposed for estimating diffusion combustion stability. A comparison of the modeling results with experimental data allows one to determine the water vapor concentration and to find the thermal balance of hydrate combustion.