Colorless Distributed Combustion (CDC) With Swirl for Gas Turbine Application

Colorless Distributed Combustion (CDC) can provide significant improvement in gas turbine combustor performance. CDC is characterized by uniform thermal field in the entire combustion chamber, thus avoiding hot-spot regions for low NO_x emissions (thermal NO_x) and significantly improved pattern factor. In this paper, colorless distributed combustion with swirl is investigated in detail to seek the beneficial aspects of CDC and swirl flows with focus on developing ultra low emissions of NO and CO, and much improved pattern factor. Experimental investigations have been performed using a cylindrical combustor with different modes of fuel injection, swirling air injection and gas exit stream location of the combustor. Air was injected tangentially to impart swirl to the flow inside the combustor. Results showed very low levels of NO (∼3PPM) and CO (∼70PPM) emissions at equivalence ratio of 0.7 at a high heat release intensity of 36MW/m³atm with non-premixed mode of combustion. Results have also been obtained on lean stability limit and OH* chemiluminescence under both premixed and non-premixed conditions.