Page 272 - Air Pollution Control Engineering

05_chap_wang.qxd 05/05/2004 3:50 pm Page 251
Wet and Dry Scrubbing 251

Table 17
Annual Cost Factors for Venturi Scrubbers
Cost item Factor
Direct Anmual Costs, DAC
Utilities
Electricity $0.059/kWh
3
Water $0.20/10 gal
Operating Labor
Operator labor $12.96/h
Supervisory labor 15% of operator labor
Maintenance
Labor $14.26/h
Materials 100% of maintenance labor
Wastewater treatment Variable; consult source for specific information
Indirect Annual Costs, IAC
Overhead 0.60 (operating labor + maintenance)
Administrative 2% of TCC
Insurance 1% of TCC
Property tax 1% of TCC
Capital recovery 0.1628 (TCC)
n
n
Note: The capital recovery cost is estimated as i (1 + i) / [i (1 + i) − 1], where i is the interest 10%
and n is the equipment life (10 yr).
Source: ref. 12.

1. Power (electricity) cost: Use Eq. (23) to estimate the fan power requirements, F :
p
F = 1.81 × 10 −4 (Q )(P total )(HRS) (23)
p
e,a
F = kWh/yr
p
and
Q = Q (T + 460) / 537 (24)
e
e,a
e
Q = acfm
e,a
where Q is the actual emission stream flow rate (scfm) and T is the emission
e e
stream temperature (°F).
It assumed that 2 wk out of the year the factory utilizing the Venturi scrubber is
shut down for inventory and retooling, which provides an annual operating period
of 50 wk/yr. Additionally, it is assumed the factory uses the scrubbing system 3 to
8 h shift, 5 d a week.
HRS = Annual operating = (3 shifts/d)(8 h/shift)(5 d/wk) (50 wk/yr) = 6,000 h/yr

The annual electric cost (AEC) with UEC equal to $0.059 kWh is determined using
Eq. (25):

AEC = (UEC)(F ) = $0.059(F ) (25)
P p
AEC = $