TM 5-810-15
other concern. SCR concerns include fouling or
involves modifications to pressure parts. Fuel
blinding catalyst surfaces and poisoning the catalyst
staging requires pressure part modifications for
with arsenic, lead, phosphorus or other trace
reburn fuel injection and/or OFA ports.
compounds found in coal.
3-10.
Primary air.
(9) Operation and maintenance cost
a. Air moving system. Pulverized coal firing
increases should be identified. Coal boiler bottom
requires heated primary air to dry the surface
ash systems may have to be retrofitted with ash
moisture in the coal fed to the pulverizers and to
separators and carbon recovery devices if LOI
provide the conveying medium for getting the finely
increases substantially. Ash sold for reuse may no
ground pulverized coal from the pulverizer to the
longer be attractive and could even be considered
burner and out into the furnace. This primary air is
hazardous waste. As regulations become more
supplied either by the FD fan for a hot primary air
strict additional catalyst could be needed to meet
system or a separate cold primary air fan for
NOx emissions and ammonia slip. Changing fuels
pressurized pulverizer systems; or is drawn through
could have detrimental effects on existing NOx
the pulverizer by an exhauster fan in the negative
reduction equipment.
pressure pulverizer system.
(10) Installation and retrofit of various NOx
(1) The use of a separate high pressure fan
reduction systems have unique installation and
to force the coal through the mill and burner lines
space requirements that should be considered. LNB
to the furnace burner and out into the furnace itself
may or may not require pressure part modifications.
requires all the burner piping, and pulverizer to be
FGR involves routing large ductwork. OFA is very
sealed against this pressure in order to prevent coal
effective, involves routing of ductwork, and also
leaks.
3-16
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