Page 266 - Air Pollution Control Engineering

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Wet and Dry Scrubbing 245

Table 14 (Continued)

Application Construction Material
Asphalt
Batch plants – dryer Stainless steel
Transfer points Carbon steel
Glass
Container Stainless steel
Plate Stainless steel
Borosilicate Stainless steel
Cement
Wet process kiln Carbon steel or stainless steel
Transfer points Carbon steel

where Q is the saturated emission stream flow rate (acfm), T is the temperature of
e,s e,s
the saturation emission stream (°F), T is the temperature of the emission stream at
e
inlet air (°F), Q is the actual emission flow rate from Eq. (24) (acfm), and Q is the
e,a w
3
volume of water added (ft /min or cfm).
T is estimated using the psychrometric chart shown in Fig. 4 with values for L and
e,s w,a
T . The inlet lb of H O per lb of dry air (L ) is determined by converting M from
e 2 w,a e
percent volume to the lb of H O per lb of dry air as follows:
2
L = (M / 100) (18/29) = lb water/lb dry air
w,a e
The adiabatic saturation line is determine on the psychrometric chart by determining
the intersection of the humidity (L ) and the inlet temperature (T ). This adiabatic
w,a e
saturation line is followed to the left until it intersects the 100% relative saturation
line. At this intersection, the temperature of the saturated emission (T ) is read from
e,s
the ordinate and the saturated emission (L ) is read from the abscissa.
w,s
T = °F
e,s
Q = Q (D )(L − L ) (1/D ) (29)
w e,ad e w,s w,a w
where Q = (1 − L ) Q (acfm) (29a)
e,ad w,a e,a
3
D is the density of the polluted air stream (lb/ft ), L = 0.10 saturated lb water/lb
e w,s
dry air (from Fig. 4), L = 0.031 inlet lb water/lb dry air (from Fig. 4), and D is
w,a w
3
the density of water vapor (lb/ft ).
Using the ideal gas law, an approximate density of any gas encountered in an air pol-
lution control project can be made:
D = (PM) / (RT) (30)
3
where D = D is the density of emission (lb/ft ), P is the pressure of the emission
e
stream (1 atm), M is the molecular weight of the specific pollutant gas (lb/lb-mole), R
3
is the gas constant (0.7302 atm-ft /lb-mole °R), and T = T is the temperature of the
e,s
gas (°R).
The density of the emission stream is calculated from Eq. (30):
D = ft /lb
3
e
The density of water vapor is determined from Eq. (30):