Dissociation and combustion of mixed methane-ethane hydrate

• Published in: Fuel (Guildford) 2022-10, Vol.325, p.124771, Article 124771
• Main Authors: Antonov, D.V., Donskoy, I.G., Gaidukova, O.S., Misyura, S.Ya, Morozov, V.S., Nyashina, G.S., Strizhak, P.A.
• Format: Article
• Language: English
• Subjects: Anthropogenic gas emissions; Combustion; Dissociation; Experiment; Mathematical modeling; Methane-ethane gas hydrate
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.124771

[Display omitted] •Dissociation and combustion rates of methane-ethane hydrate are higher than for methane.•High water vapor concentration can reduce anthropogenic emissions.•Maximum dissociation rate of gas hydrates is achieved by heating.•Service water provides faster hydrate synthesis than distilled water.•New model describes the dissociation and combustion of methane-ethane hydrate. Non-isothermal decomposition of mixed methane-ethane hydrate in a furnace is studied experimentally and theoretically with varying temperature. Over the combustion duration, the dissociation rates of the gas hydrate powder and tablet are approximately estimated under five different combustion schemes: at decomposition in a high-temperature muffle furnace and during induction heating under different boundary conditions of heat exchange. With an increase in the temperature in the furnace from 890 K to 1350 K, the dissociation rate of methane-ethane hydrate increases by 25–50%. The maximum dissociation rate corresponds to a thin layer of powder in the furnace at a temperature of 1350 K. Gas release is measured at combustion using a gas analyzer: H2, CH4, CO, CO2 and NOx. The emissions of nitrogen and carbon oxides from the combustion of methane-ethane hydrate are shown to be much lower than from the combustion of high-potential and conventional fuels. It is established that the high concentration of water vapors from the combustion of methane-ethane hydrate can reduce anthropogenic gas emissions. The concentration of unreacted methane gases drops significantly with increased temperature in the furnace. A mathematical model was developed to describe the dissociation and combustion of a porous methane-ethane hydrate layer, accounting for ice melting, water evaporation, as well as convective flows in the gas mixing layer. The simulation results correspond to the experimental data. The obtained results may be used to improve the combustion efficiency of double hydrates, as well as to reduce emissions of both combustible H2 and CH4 gases and harmful emissions of CO2 and NOx.