In the case where water was injected together with the secondary air, the outlet mass fraction of CO was increased by 50 %. This originated from local spots of low temperatures caused by the presence of water. The two cases where areas of the furnace wall were insulated, reduced CO emissions were obtained. The reductions was most significant in the case where 60 m2 (19%) of the wall was insulated, where CO emissions were reduced by 33 %. In practice, the CO reductions obtained by insulating furnace walls are more significant. This was not fully resolved by the model used. Most likely, the phenomenon causing high CO emissions in practice, are cold regions near the walls, why a better resolution of the boundary layer had been needed. In general, the effects of different temperatures, the creation of radicals etc. was excellent modelled using a detailed kinetic mechanism with the EDC, features that cannot be resolved with simple chemistry models.