Characteristics of Combustion of Rich-Lean Burner Controlled Boundary Region between Rich and Lean Flames

2nd Report, Effects of Mixture and Air Supplied into Boundary Region on Practical Combustion Region

Abstract

Effects of the velocity and the air ratio of the mixture and the air supplied into the boundary region between the rich and lean flames on the characteristics of the rich-lean combustion were investigated in order to develop a new type of a domestic boiling water heater and a warm heater with low emission of NO_x and high TDR. The characteristics of flame stabilization of the rich-lean combustion are improved even under the condition of the practical combustion when the stoichiometric, lean mixture and the air are supplied into the boundary region between the rich and lean flames. The stable combustion is achieved under the condition of 1.34 times of the normal load combustion by ontrolling the boundary region. The emission of NO_x is decreased when the air is suplied into the boundary region between the rich and lean flames. Especially, the effects of NO_x reduction are noticeable under the conditions of low load combustion. Therefore, it is possible to prevent combustion oscillation and combustion noise with low frequencies from occurring, and to develop the new type of burners with high performance of high TDR and further low emission of NO_x by supplying the mixture and the air into the boundary region between the rich and lean flames in the rich-lean combustion.