Combustion of Ethane with Small Concentrations of Methyl Chloride Tube Burner

Abstract

Premixed, thermally stabilized combustion inside a refractory-tube without a flameholder has a number of unique characteristics that are favorable for incineration. Owing to the fully developed turbulent flow, the velocity, temperature and composition are relatively uniform across the channel, Because of the absence of backmixing other than the negligible degree associated with confined turbulent flow, the flame front is a virtual step in temperature and composition. Owing to the thermal feedback by wall-to-wall radiation and in-wall conduction, the temperature of the stream of gas immediately behind the flame front exceeds the adiabatic value, and owing to the great thermal inertia of the refractory tube and the plug-like flow, the combustion is very stable and free of oscillations. Most important of all, the temperature of the wall is close to that of the gas throughout the burner. The net effect of these characteristics is that every molecule of the gaseous mixture experiences essentially the same period of extreme and nearly uniform temperature. In the current investigation small concentrations of methyl chloride (0.02 to 0.11 mole per mole of ethane) in a slightly lean mixture of ethane and air were passed through a round, 19.5-mm channel in a ceramic block. The concentration of chlorohydrocarbons in the exit gas was below our level of detection (∼ 1 ppm), and supporting theoretical calculations with a detailed kinetic model predicted concentrations of only a few parts per trillion (a reduction by a factor of about 10,⁸). The addition of the methyl chloride did not affect the combustion significantly.

Keywords:

• Incineration
• chlorohydrocarbons
• thermally stabilized combustion