Examination of the combustion gas / air mixing in a gas burner

For reasons related to energy and environment policy as well as for economic reasons, process gases actually generated as “waste products“ are thermally recycled and used for energy production in a steel plant. After the conversion of the boiler operation mode from separate furnace and converter gas combustion to mixed gas operation, problems occurred regarding flame stability and full load parameters during burner operation. The reason supposed was an inadequate combustion gas / air mixing in the burners, and so the flow situation on the mixed gas burners had to be simulated numerically. For this purpose, based on planning documents the burner geometry has been modelled as accurate and detailed as possible. However, as the documentation did not include complete information on the actual design of the burner and as the burner had partly been converted without any relevant documentation, the current state of the burner design had to be documented on-site insofar as it has an impact on the flow situation. Based on these data and parameters a numerical model could then be generated.

The CFD calculations referring to the current state could be confirmed by plant measurements and experiences made by the operation team and provided important information on the flow situation. In fact, an inadequate mixing of the gases could be detected, thus confirming the initial presumption. Based on these findings, new variations providing better mixing have been developed, and then examined and evaluated by means of CFD.