Fixed bed boilers are widely used to fire coal for heat and power production. However, these systems are often reported to have relatively high unburnout, low efficiency and high emissions, in addition to needing to be optimized and modernized. In this work, the measurements were performed in a test rig, where a combustion front propagates against the airflow. The author decided to use function to describe the simplified profile of emissions. The results obtained from measurements were converted in the form of approximation functions. Furthermore, developed functions were applied for defining...