For the first iteration step of the furnace simulation, a number of about 12,000 iterations was necessary to reach a converged solution. For the following furnace simulations 2000–3000 iterations only were sufficient due to the fact, that the solution of the previous iteration step was used as the initial condition for the simulation of the furnace. The convergence was determined by residuals for all equations below a value of 10−3. Temperature and A-674563 concentrations at the outlet as well as heat fluxes on the walls and billets were monitored for additional information about the simulation progress. Also the maximum error of the energy balance for all iteration steps of the furnace was 0.17% compared to the thermal input of 18.2 MW.
3.2.2. Boundary conditions and numerical grid
Fig. 7. Numerical grid of the furnace (a) and the burner (b).Figure optionsDownload full-size imageDownload as PowerPoint slide
3.2.3. Combustion and radiation models
The aim of this study was to simulate the combustion process and the transient heating of the steel billets with high accuracy and a low calculation time. Hence the selection of the appropriate combustion and radiation models was crucial.