Page 297 - Materials Chemistry, Second Edition

280 Practical Design Calculations for Groundwater and Soil Remediation

(b) Use Equation (7.11) to determine the flow rate from the stack:

Q actual @temperature ,inacfmT = 460 +T = 460 + 200
Q standard,inscfm 460 +77 460 + 77

Q
T
= actual @temperature ,inacfm
158.8
So, Q = 195.2 acfm @ 200°F
The discharge velocity, v = Q/A = Q ÷ (πr )
2
= 195.2 ft /min ÷ [π(2/12) ft ]
2
3
2
= 2,240 ft/min
Discussion:
If the actual flow rate at one temperature is known, it can be used to
determine the flow rate at another temperature by using the follow-
ing formula:

Q actual @T 1 = 460 +T 1
Q actual @T 2 460 +T 2 (7.13)
The stack flow rate in this example can be directly determined by using
the exit flow rate from the oxidizer as:

Q actual @T 1 = 460 +T 1 = 550 = 460 + 1400
Q @T 460 +T Q @200 °F 460 + 200
actual 2 2 actual
Thus, Q actual @ 200°F = 192.2 acfm

7.3.2 Heating Value of an Air Stream
Organic compounds generally contain heating values. These organic com-
pounds can also serve as energy sources for combustion. The higher the
organic concentration in a waste stream, the higher the heat content is
and the lower the requirement of auxiliary fuel would be. If the heating
value of a compound is not available, the following Dulong’s formula can
be used:


Heatingvalue (inBtu/lb) = 145.4 C+ 620 H − O   + 41 S (7.14)

 8 
where C, H, O, and S are the percentages by weight of these elements in the
compound. Equation (7.14) can also be used to estimate the heating value of