LAMINAR BURNING VELOCITY FOR HYBRID MIXTURES OF CORN STARCH DUST AND METHANE GAS AT HIGH INITIAL TEMPERATURE

Abstract

A small quantity of flammable gas mixed with dust can cause a large explosion with severe consequences. In this study, hybrid mixtures explosion tests were performed in a constant volume 0.02 m3 spherical vessel. Five pressure-time curves were recorded. The effects of initial temperature on burning velocity were investigated for Lycopodium Clavatum-methane-air hybrid mixtures. The most important results from evaluated experiments are the values of burning rates to understand better the fundamental flame methane-air process in hybrid mixtures. The burning velocity is known to be altered by turbulence. It depends on the coupling interaction between the explosion pressure, the rate of pressure rise, the volume of the vessel, and the ignition source. When discussing hybrid mixtures, the focus is on an admixture of flammable gas in concentrations below the lower explosive limit of the gas itself. If this limit for the gas is exceeded, one soon has a situation where the worst-case scenario for a primary explosion would be a pure gas explosion. In the present study, we highlight the first evaluation of laminar burning velocity determined with electrical point ignition at higher initial temperatures. The experiments have been performed in a 0.02 m3 constant volume vessel of spherical shape adopted for the hybrid mixture experiments. The laboratory-size vessels used in the presented study are geometrically similar, have different sizes, and with point ignition. The values of burning velocity varied when the temperature is higher than 25 -C, and the cube-root law was affected. The initial temperature rise does not affect the dependence between the maximum rate of pressure rise and the maximum explosion pressure in the Cube-root law formula.