Large refinery burners are supplied with combustion air through a network of ducts, valves and dampers. During start-up or changes in operating conditions, one or more burners may become unstable if the air is distributed unevenly through this network.
FlowMotion combined engineering analysis, measurements and CFD to identify the cause of these disturbances. Local flow velocities and static pressures were determined throughout relevant parts of the air-supply system.
Particular attention was paid to large recirculation zones and vortical flow structures generated by bends, dampers and other geometric transitions. These structures can produce a strongly non-uniform velocity and pressure distribution at the burner inlets.
Pressure measurements at selected positions in the duct system were used to assess the numerical results and improve understanding of the complete installation. CFD then allowed modifications to individual components and operating settings to be evaluated.
The combined approach provided a physical explanation for the unstable burner air supply and a basis for improving flow distribution between the burners.
