Challenges in Validating Recovery Boiler Furnace Models in Practice, 2010 TAPPI/PAPTAC International Chemical Recovery Conference

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Computational Fluid Dynamics (CFD) plays a significant role as a tool in recovery boiler design, retrofits and in troubleshooting. Accurate computational results require, in addition to sub-models that describe the problem well, correct input parameters and correct boundary conditions. In order to develop the furnace models further, models need to be validated in real environment and conditions. However, it is very difficult, expensive and time consuming to get reliable experimental information from inside the furnace.

This paper presents an advanced experimental method, a multi-purpose furnace probe developed by Andritz Oy, to collect reliable information for validation of furnace models. This paper describes also measurements with the probe and CFD-simulations for two operating cases with different air models. In order to gain as reliable input parameters as possible for CFD, air velocity at each air port was measured, experimentally determined initial spraying parameters were used, and liquor samples were analyzed. The furnace probe measurements were carried out at the maintenance level forming a full coverage of the whole cross sectional area with 24 measurement point locations.

One of the main tasks was to assess how accurately the CFD results compare with the field data. The results of CFD-calculations with the Andritz furnace model follow well the main features of the recovery boiler in practice. The location of the char bed was correct and the distribution of oxygen and temperature agreed well with the measurement data.