1. Review projects to determine feasibility of
purchasing an additional compartment for
out-of-service maintenance.
2. Provide a manual flue gas bypass system for oil
firing startup and provide also an automatic flue
gas bypass system for use during operational upsets,
should flue gas temperature exceed the bag material
temperature limit or should baghouse pressure drop
exceed paragraph entitled "Design Criteria" by 10
percent. This is particularly important if the
standby fuel is oil. Local environmental
regulations may require a waiver to permit this
necessary feature.
3. The air-to-cloth ratio effects the baghouse
pressure drop, bag failure rate, and bag life. It is
dependent upon the bag cleaning system, frequency of
cleaning, and dust loading. Most reverse air
baghouses have a net air-to-cloth ratio of 2-2.5 to
1. The Navy recommends use 2 to 1. Most pulse jet
baghouses will have a net air-to-cloth ratio of
4-4.5 to 1, based on a continuous cleaning cycle.
The Navy recommends use 4 to 1.
4. Pressure drop across the baghouse, measured
after the bags have had time to season in service,
is a function of the air-to-cloth ratio, inlet dust
loading, and dust particulate characteristics. For
a 2 to 1 air-to-cloth ratio and 4.60 g/m3 2 grains
per acf inlet dust loading, the flange to flange
pressure drop should be approximately 1245 Pa 5
inches WC.
5. Use a 55 degree hopper valley angle unless the
ash is "sticky" as for Western coal, or if moisture
content is high; then use a 60 degree angle. Ash
hopper collection capacity should be approximately 8
to 10 hours using 1/3 of the hopper volume.
**************************************************************************
Design baghouse(s) complete with structural supports, weather enclosure,
manifolds, ductwork, dampers, bags, bag cleaning system, hoppers, and
accessories to meet OSHA regulations, ICAC F-2, ICAC F-3, ICAC F-5, and the
following criteria. Base applicable criteria on maximum flow conditions
specified in the above paragraph with two compartments out of service; one
out of service for cleaning and one out of service for maintenance.
a.
Maximum outlet particulate emissions loading, grams per dry std cu
meter grains per dry std cu ft [_____]
b.
Maximum gas velocity, m/s fps [_____]
c.
Minimum number of online compartments ____4____
d.
Maximum net air-to-cloth ratio, L/s per sq meter acfm per sq ft
(at maximum continuous rating, including volume used for reverse
air) [_____]
SECTION 15863N
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