Flow processes in a radiant tube burner: Combusting flow

This paper describes a study of the combustion process in an industrial radiant tube burner (RTB), used in heat treating furnaces, as part of an attempt to improve burner performance. A detailed three-dimensional Computational Fluid Dynamics model has been used, validated with experimental test furnace temperature and flue gas composition measurements. Simulations using the Eddy Dissipation combustion model with peak temperature limitation and the Discrete Transfer radiation model showed good agreement with temperature measurements in the inner and outer walls of the burner, as well as with flue gas composition measured at the exhaust (including NO). Other combustion and radiation models were also tested but gave inferior results in various aspects. The effects of certain RTB design features are analysed, and an analysis of the heat transfer processes within the burner is presented.

► 3D combusting flow in an industrial radiant tube burner is modelled using the ANSYS-CFX CFD code.
► Results are validated against data from an industrial furnace (NO emissions within 7%).
► The flame is long and narrow with slight asymmetry. Mixing near the fuel injector is very effective.
► The recuperator section is reasonably effective, but design improvements are proposed.
► The design is vulnerable to eccentricities due to manufacturing or assembly tolerances.