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88 Lawrence K. Wang et al.

Fig. 4. Structure costs for reverse-air filters.

expected for mechanical shaking or reverse-air cleaning, and an A/C ratio of about 5.0
is expected for pulse-jet cleaning.
A fiberglass bag would provide the most protection during temperature surges
(unless ceramics are used), and because fiberglass bags may be less expensive, it may
be the fabric of choice for an installation with these emission characteristics.
Fiberglass bags would require that reverse-air cleaning be used, unless a suitable back-
ing allows pulse-jet cleaning. Teflon bags with mechanical shaking could also be a
possibility (7,17). Limited information on the long-term effectiveness of ceramics has
been documented. It is expected that ceramic fibers will have performance character-
istics similar to the best synthetic fibers, but will cost significantly more.
Example 8
The HAP emission stream shown in Example 7 and Table 11 is to be treated by a reverse-
air baghouse. Figure 4 is provided by the vendor for the cost of the baghouse structure.
Determine the A/C ratio, net cloth area (A ), gross cloth area (A ), and the baghouse total
nc tc
capital cost (requiring stainless steel add-on and insulation).
Solution
1. From Table 4, flyash, the A/C ratio = 2.5.
2
2. Thus, A = (110,000 acfm)/2.5 = 44,000 ft .
nc
3. Obtain the total cloth area using Table 5. This table indicates that A should be mul-
nc
2
tiplied by 1.125 to obtain A . Thus, A = 44,000(1.125) = 49,500 ft . This value is
tc tc
used to obtain the structure cost.
4. Using Fig. 4, the structure cost equals $380,000 plus $270,000 for stainless-steel add-
on, plus $40,000 for insulation. The total cost is then $380,000 + $270,000 + $40,000 =
$690,000.