Effect of surfactant on the methane hydrate combustion

Effect of surfactant, sodium dodecyl sulfate (SDS) on the methane hydrate combustion has been investigated experimentally. Water solution of 0-2300 ppm SDS and methane are used to form the methane hydrate with SDS. Methane hydrate of 30 g was placed in a petri dish with 100 mm inner diameter and 10mm depth. The upper surface is opened to the air and is flushed. The temperature at 1.5 mm below from the upper surface of the petri dish along the centerline was measured by a K-type thermocouple. The petri dish is placed in a vertical flow channel where the honeycomb is installed to stabilize the upward flow due to the natural convection by combustion. When the temperature reaches the ignition temperature, the hydrate is ignited at the center by a pilot burner. The flame motion is recorded by a high-speed video camera with 125 fps and the temperature data from the thermocouple is stored in a data logger. In the case of the methane hydrate with SDS, a large amount of soapy bubble was formed shortly after the ignition over the hydrate surface. The bubbles decrease the heat from the flame to the hydrate surface and then the flame is weakened and extinguished faster than the pure methane hydrate. The bubbles stifle to form an anomalous preservation zone and then the distinct decrease in the flame propagation speed is not observed.