Total Capital Costs

Total capital costs include costs for the baghouse structure, the initial complement of bags,
auxiliary equipment, and the usual direct and indirect costs associated with installing or
erecting new structures. These costs are described below, and may be escalated if desired.
See EPA's OAQPS Cost Control Manual (EPA 1990) for escalation techniques.
Structure Cost

Table associates a figure (found later in this lesson) with each of the six types of
fabric filters listed. Each figure consists of a graph that plots the following three structural
costs as a function of gross cloth area:

1. Cost of the filter structure (without bags)
2. Additional cost for 304 stainless steel construction
3. Additional cost for insulation

Extrapolation of these lines is not recommended. All units include unit and exhaust
manifolds, supports, platforms, handrails, and hopper discharge devices. The indicated
prices are flange-to-flange. Note that the scales on axes differ.

The 304 stainless steel add-on cost is used when stainless steel is necessary to prevent
the exhaust stream from corroding the interior of the baghouse. Stainless steel is substituted
for all metal surfaces that are in contact with the exhaust gas stream.

Insulation costs are for 3 inches of shop-installed glass fiber encased in a metal skin.
One exception is the custom baghouse, which has field-installed insulation. Costs for
insulation include only the flange-to-flange baghouse structure on the outside of all
areas in contact with the exhaust gas stream. Insulation for ductwork, fan casings, and
stacks must be calculated separately.

The costs for intermittent service, mechanical shaker baghouses (including the shaker
mechanism) as a function of gross cloth area are presented in Figure 1. Because
intermittent service baghouses do not require an extra compartment for cleaning, gross
and net fabric areas are the same.
The same costs for a continuously operated baghouse cleaned by mechanical shaker as
a function of the gross cloth area are presented in Figure 2. As in Figure 1, the
units are modular in construction. Costs for these units, on a square foot basis, are
higher because of increased complexity and generally heavier construction.
Costs of common-housing pulse-jet units and modular pulse-jet units are presented in
Figures 3 and 4. Modular units are constructed of separate modules that may be
arranged for off-line cleaning, while common-housing units have all bags within one
housing. The cleaning system compressor is not included. Because the common housing
is relatively inexpensive, the stainless steel add-on is proportionately higher than
for modular units. Added material costs and set-up and labor charges associated with
the less workable stainless steel account for most of the added expense.
The costs for the reverse-air baghouses are shown in Figure 5. The construction is
modular and the reverse-air fan is included. Costs for custom baghouses which must
be field assembled because of their large size are given in Figure 6. These units
often are used on power plants, steel mills, or other applications too large for the factory-
assembled baghouses.

Figure 1. Structure costs for intermittent shaker filters

Figure 2. Structure costs for continuous shaker filters

Figure 3 Structure costs for pulse-jet filters (common housing)

Figure 4. Structure costs for pulse-jet filters (modular)

Figure 5. Structure costs for reverse-air filters

Figure 6 Structure costs for custom-built filters