D7.3 Oxyfuel CFD burner and large kiln simulations

Oxy-fuel combustion in cement kilns is one of the capture technologies investigated in the
CEMCAP Project. The present deliverable reports on optimization of a full-scale rotary kiln
operating in oxy-fuel mode by using Computational Fluid Dynamics (CFD) and interaction with
process simulation. An optimization procedure and a set of constraints have been defined and
followed. The oxy-fuel flame is investigated at different input flow conditions at the burner and
secondary gas stream from the clinker cooler, with the objective of reproducing a heat radiation
profile to the clinker which is as close as possible to the BAT air reference case defined in
CEMCAP. An acceptable trade-off has been found between kiln gas inlet conditions
(composition and flow rates) and the boundary constraints imposed to the kiln in terms of
hardware, process flow, and heat radiation to the clinker. The ThyssenKrupp designed
POLFLAME burner has demonstrated to be able to generate an oxy-fuel flame with similar heat
transfer characteristics in air and oxy-fuel requiring only to adapt the modulable swirl angle of
the burner high velocity nozzles. Retrofit applications and air/oxy-fuel mode shifting are
therefore possible without changing the burner. The study has shown the particular features of
flame stabilization pattern with this burner and highlighted the rotary kiln characteristics that
were most sensitive to the flame properties.