Numerical Simulation of Full Oxy-Fired Oscillating Combustion

Oscillating combustion represents a complex process, leading to significant improvements in high temperature industrial applications. Field demonstrations of the oscillating combustion technology have shown a significant reduction in NO_x emissions, increased efficiency and improved operation. To date, no modeling work has been able to quantify these impacts of the technology. This effort presents the results of a numerical simulation study of oscillating combustion in a 450 kW pilot furnace. The combustion process involves a pipe-in-pipe natural gas-fired burner using exclusively oxygen as oxidant. The fuel is introduced into the combustion chamber periodically, given a certain amplitude and a time period, while the oxidant is introduced continuously. The transient numerical simulation uses the Air Liquide proprietary computational fluid dynamic software ATHENA™, analyzing the combustion process at incremental timesteps. The results reported here clearly explain the phenomena observed in the lab, as well as in field demonstrations. Detailed analysis of the mixing process between the fuel and oxidant, combustion of the reactants and heat transfer to the furnace walls is included. It is concluded that oscillating combustion represents a powerful solution to many industrial applications, and that modeling can play an important role in explaining the process, and in optimizing the system operation.