In straight grate burning machines, heat is transfered from combustion area to pellets' bed by means of fans using windboxes. Commonly, a PID algorithm controls temperature and there are fixed temperature set-points to control fans' speed variation. Once there is a delay between process variations and temperature changes, due the slow response of this variable, the control system does not match the heat needs of pellets. This causes overheating or underheating. In CVRD'S Pelletizing Plants number 5 and 6, it was implemented a selective control algorithm to antecipate the feed rate variations, keeping pressure and temperature stable. The flexibility of this algorithm has reduced manual interventions in process. The estimated savings in both plants were about 1.5 kWh/t, which means 12600 MWh per year. The total savings, for the 7 plants, can achieve 42300 MWh per year.
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