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238 Lawrence K. Wang et al.

3. Operating Labor Cost: It assumes that 2 wk out of the year the factory utilizing the
absorber is shut down for inventory and retooling, which provides an annual oper-
ating period of 50 wk/yr.
Operating labor = (0.5 h/shift)(3 shifts/d)(5 d/wk)(50 wk/yr)($12.96 /h)
Operating labor cost = $
Supervisory cost = 0.15 (Operating labor)
Supervisory cost = $
4. Maintenance Costs
Maintenance labor cost = [(0.5 h/shift)(3 shifts/d)(5 d/wk)(50 wk/yr)]($14.96/h
labor cost)
Maintenance labor cost = $
Maintenance materials cost = 1.0 (Maintenance labor)
Maintenance materials cost = $
5. Total Annual Direct Costs = 1b + 2b + 3 + 4 = $

C. Indirect Annual Costs of Absorbers
These expenses are obtained from the factors given in Table 7, and the summation of
these expenses provides the total indirect annual costs.
Overhead = $
Property tax = $
Insurance = $
Administration = $
Capital recovery = $
Total Indirect Annual Cost = $
D. Total Annual Costs = Total Direct Annual Costs + Total Indirect Annual Costs
Total Annual Costs = $

Example 11
The cost of a wet scrubber system (see Fig. 1b) is estimated in this example. The scrubber
upon which this estimate is based is the scrubber designed to treat Emission Stream 5
(Table 11) in Examples 1, 3, 5, 7, and 9. The methodology of the determination is similar
to the procedure detailed in Example 10.
Solution
A. Purchase Equipment and Total Capital Costs
The diameter of the column is 4 ft, from Example 5. Extrapolating from Figure 7 (see
Example 10), the cost of a single bed tower is approx $25,000. The volume of pack-
3
ing, V needed to fill the tower is 290 ft . Assume that 2-in. ceramic porcelain
packing
Raschig rings are used to pack the tower. The cost of this packing is given in Table 12
as $12.75 per cubic foot. The total packing needed for the project therefore will cost
$3700. A figure of $10,000 is assumed for the expense of auxiliary equipment. The
equipment cost (EC) is the summation of these costs:

Cost of a single bed tower = $25,000
Cost of this packing = $3,700
Cost of auxiliary equipment = $10,000
Equipment cost (EC) = $38,700