ahead of and at the entrance of the dust collector(s) to ensure even gas
flow into the dust collector(s).]
1.3
PERFORMANCE
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NOTE:
1. The stack emission or efficiency requirement
must comply with either (a) weight emission
standards: (b) opacity regulations; or (c) community
standards for visible emissions. Compliance with
existing emission codes may not satisfy the opacity
regulation. Similarly opacity regulations may not
be as demanding as community standards. A specific
quantitative emission rate must be selected on the
basis of the goals established.
2. Stack opacity is influenced by particle size
makeup. For example, with pulverized coal-fired
boilers, about 45 percent of ash particles are below
10 microns in size; for a cyclone-fired boiler,
about 70 percent are below 10 microns; for a
stoker-fired boiler, about 25 percent are below 10
microns. A visually acceptable stack for these
three options might require residuals of 0.046 g/m3
0.02 gr per cf, 0.023 g/m3 0.01 gr per cf, and
0.0929 g/m3 0.04 gr per cf, respectively.
3. A 90 percent overall collection efficiency may
be attainable with most coals burned in underfeed or
gravity feed stoker-fired boilers. Mechanical
cyclones must be viewed as a part of an air
pollution system on boilers or incinerators. When
used as precleaners in conjunction with
electrostatic precipitators (ESP) or baghouses, a
high efficiency cyclone is not necessary and may
even adversely affect the high efficiencies of the
ESP or baghouse. In addition, 90 percent efficiency
is dependent upon particle size, distribution and
concentration as well as the collector being or not
being used in conjunction with higher efficiency ESP
or baghouse collectors. The large diameter cyclones
do have a low pressure drop, but the high efficient
multitube collectors operate in a range from 747 to
1992 Pa 3 to 8 inches water gage.
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[Multitube] [Centrifugal cyclone] collector shall operate with a minimum
overall collection efficiency of [_____] percent at a maximum draft loss of
[1992] [249] Pa [8] [1] [_____] inch water gage when operating at maximum
[continuous] [peak] rating of flue gas flow conditions, dust loading, and
dust particle size distribution specified in paragraph entitled "Inlet Gas
Conditions."
SECTION 15861N
Page 7
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