Fuel staging or fuel reburning is a possible primary measure for the reduction of NO V emissions from fossil-fired steam generators. It is intended to investigate if this primary measure can be applied efficiently to coal-fired combustion systems where pulverized coal is also used as a reburning fuel: coal reburning over a coal fire. This technology has to be tested accordingly. The company ENE¸SpA is at present evaluating, together with ANSA¸DO Energia SpA, the option of demonstrating and extending the use of this technology in its coal-fired utility steam generators. Both companies have decided to erect a boiler simulation facility (5 MWth) at ENEL's experimental area Santa Gilla (Cagliari). This facility is intended to replicate the time/temperature profiles of real boilers. One tool to support the design of firing systems is CFD simulation. Consequently, CFD simulation was applied to perform a 'proof of concept'. Most important for the design of firing systems for the furnaces of utility steam generators or test facilities is the distribution of temperature inside the combustion chamber and the furnace exit temperature -especially the radiation transport responsible for the amount of energy transferred from the gaseous environment of the hot furnace to the furnace walls. Subsequently, this determines the mean furnace exit temperature. This is why the accuracy of temperature calculations depends directly on the radiation transport model, the gas emissivity approximations, the particle emissivity and the radiative properties of the furnace enclosure. The results of several combustion simulations of the coal reburning test facility are shown and discussed. Estimates of the possible effect of different wall temperatures on the combustion process itself and on the gas temperature inside the furnace are presented.