At Milliken, the existing ABB LowNOx
Concentric Firing System™
(LNCFS-III), which includes both close
coupled and separated OFA ports, was
used for the reburn project. Pulverized
coal is provided by four DB Riley MPS
150 mills with dynamic classifiers. With
LNCFS-III there are four levels of burners,
and each mill serves one burner level.
When using reburning, the top-level burner
nozzles were used to feed the reburn fuel
into the upper part of the furnace. To simulate
and test a reburn application, the lower
three coal elevations were biased to carry
approximately 80% of the fuel required
for full load, with the top burner supplying
the remaining fuel. The speed of the
dynamic classifier serving the mill feeding
the top burners was increased to provide
the micronized fuel. It was decided that
full conversion to micronized coal would
not be cost effective.