Computer modelling of high temperature air combustion

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

High Temperature Air Combustion, HiTAC, is an innovative combustion technology which offers improved heat transfer and a reduction in fuel consumption and NOx emissions. This paper describes a project in which a computational fluid dynamic model of a furnace working on high temperature air combustion technology was developed using FLUENT® CFD software. The model was validated against experimental data obtained from KTH in Sweden. The predicted results compared very well with this experimental data, and were also closer than the predictions from the model built by KTH. The model was applied to a steam boiler of Malta’s Delimara Power Station. Two scenarios were considered: the boiler with conventional combustion and the boiler converted to HITAC. To reduce computational time, a 400:1 scaled down version of the boiler was modelled based on NOx scaling. Further reductions were made by taking advantage of the symmetry of the boiler and by obtaining the solution for a single burner, and then prescribing the parameter profiles for the single burner to the full boiler model as boundary conditions. The computer model results showed much lower NOx emission levels when firing the boiler with methane compared to heavy fuel oil. Further reductions in NOx emissions were obtained with HITAC technology and using methane as a fuel.