Analysis of High Temperature Air Combustion (HTAC) boiler for efficient and clean power production using computational fluid dynamics

Continuously increasing fossil fuels consumption and environmental pollution are the motivations to investigate new power generation technologies, featured with high efficiencies and low emission of harmful substances. HTAC technology (High Temperature Air Combustion) is one of such technologies. Although HTAC technology seems to be attractive for power boilers there are still many open questions. The authors of the present paper aimed to perform numerical simulations, which should estimate expected advantages and disadvantages of HTAC application in boilers and impact of this technology on the environment. In this paper the authors analyze an optimal design of the new concept of the boiler working in HTAC mode fueled with pulverized coal, which was used in previous investigations [1,2]. Calculations were done using the CFD Fluent code 6.2.16. Performed investigations allowed estimating of temperature, concentration and velocity fields in the boiler, especially NO_x and CO emission and the heat transfer on the walls. It was found that is possible and advantageous to apply HTAC technology in boilers. The heat transfer inside the boiler is significantly improved in comparison with standard boilers, which leads to make the boiler smaller, and at the same time could be economical profitable build this boiler as super critical and increase the efficiency of the entire power cycle. Furthermore, it was found as possible to operate this boiler with the air excess ratio slightly above 1, decreasing at the same time the amount of the flue gas and the outlet physical loss. Additionally the nitric oxide emission is founded very low in comparison with standard boilers fired with pulverized coal.