The use of nonsymmetrical jets for the stabilization of low grade coal flames

Two new aerodynamic methods of flame stabilization have been developed which are especially suitable for low grade pulverized coals or coal-water-slurries. One is based on the Coanda effect, which causes the flat inlet jet of air to attach to the bottom of the precombustion chamber and creates a large recirculation in the upper half of the chamber with strong turbulence and mixing. The inertia of the coal particles projects them into the high temperature zone, thus they quickly ignite and burn, leading to a stable flame. The other is based on an off-axis, slightly tilted primary jet, which produces a three-dimensional flow-field with large recirculation and good mixing. The distribution of coal is also favorable for stable combustion.