Cofiring of hydrogen and pulverized coal in rotary kilns using one integrated burner

The grate-kiln process for iron-ore pellet induration utilizes pulverized coal fired burners. In a developed infrastructure for H 2 , it might be desirable to heat the existing rotary kilns with renewably produced H 2 . Technical challenges of H 2 heating of grate-kilns include high emissions of NO X and maintaining sufficient heat transfer to the pellet bed. This article examined cofiring (70% coal/30% H 2 ) in 130 kW experiments using two different integrated burner concepts. Compared to pure coal combustion, cofiring creates a more intense, smaller flame with earlier ignition and less fluctuations. The process temperature and heat transfer are enhanced in the beginning of the kiln. The co-fired flames emit 32% and 78% less NO X emissions compared to pure coal and H 2 combustion, respectively. We can affect the combustion behavior and NO X emissions by the burner design. H 2 /coal cofiring using integrated burners is probably an attractive solution for emission minimization in rotary kilns. • Pure H 2 combustion faces obstacles replacing coal in current induration kilns. • Coal and H 2 cofiring is investigated as an alternative. • Cofiring enhances the ignition of coal particles and stabilizes the flame. • Cofiring emits less NO X emissions compared to traditional pure coal and pure H 2 . • Cofiring and pure H 2 flames offer elevated heat transfer close to the burner.