The influence of key parameters on combustion of double gas hydrate

Abstract

The combustion and dissociation of the double hydrate of propane-methane have been studied in terms of several key parameters: the velocity of the forced air flow U0, heat flux, temperature difference, and geometry of the work area. Simple expressions relating the dissociation rate with the specified key parameters have been obtained. The ratio of dissociation rates J1/J2 was determined, where the dissociation rates J1 and J2 correspond to the experiment with and without combustion, respectively. At U0 = 0 m/s, the ratio J1/J2 equals 8–9, and in the presence of forced gas flow J1/J2 = 11–12. Forced convection increases this ratio. Approximate correlations have been obtained for assessing the time of combustion beginning and the duration of the gas hydrate burning. The dissociation rate is nonlinearly related to the velocity U0. Two characteristic modes of gas hydrate dissociation are distinguished. Measurements of velocity fields obtained using the Particle Tracking Velocimetry (PTV) method show that the interaction of forced and free convection flows leads to a decrease in the maximum resultant velocity. Due to fuel excess over the oxidizer (violation of stoichiometric ratio), there are periodic emissions of gas bubbles, leading to incomplete combustion of the fuel. To improve the efficiency of combustion, it is advisable to use velocities U0 = 1.2–3 m/s. A further increase in U0 leads to the extinguishing of the flame.