Current through Reg. 50, No. 13; March 28, 2025
(a) Application.
Determination of the net ground level concentration shall be performed in
accordance with the procedures outlined in §
112.33 of this title (relating to
Calculation Methods) for hydrogen sulfide and this section for sulfuric acid
(H[sub]2[/sub]SO[sub]4[/sub]).
(b)
Determination of compliance with emission limits. In most cases downwind
samples will suffice; however, if the sampled properties are suspected of being
influenced by an upwind source of H[sub]2[/sub]SO[sub]4[/sub], then both upwind
and downwind samples will be taken. The concentration of
H[sub]2[/sub]SO[sub]4[/sub] in the downwind sample less the concentration in
the upwind sample shall be used in determining whether the emissions from the
property comply with the requirements of §
112.41 of this title (relating to
Allowable Emissions). Calculated maximum allowable emission rates or ground
level concentrations which are obtained by the method in subsection (c) of this
section may be used in determining whether a property is in compliance with the
emission limits specified.
(c)
Calculations of H[sub]2[/sub]SO[sub]4[/sub] concentrations from stack samples
and measurements. The maximum allowable H[sub]2[/sub]SO[sub]4[/sub] emission
rate which may be made from a stack on property to comply with the emission
limit set forth in §
112.41 of this title (relating to
Allowable Emissions) may be calculated by Sutton's equation which has been
modified to consider the critical wind speed and to correspond to a one-hour
sample. Additional credit on stack emissions can be obtained if the distance
from the stack to the property line is greater than 30 stack heights. Those
properties with greater than 30 stack heights to the property line should
contact the executive director to obtain the proper correction factor.
(1) For exit stack gas for temperatures of
less than 125 degrees Fahrenheit. The following calculations shall be used for
exit stack gas for temperatures of less than 125 degrees Fahrenheit.
(A) The H[sub]2[/sub]SO[sub]4[/sub] ambient
air level of 80 ug/M[sup]3[/sup] for one hour is used.
Attached
Graphic
(B) To
plot Graph IV, assume a basic stack height of 100 feet and plot
Attached
Graphic
sp"> for various stack diameters versus stack
velocity.
Attached
Graphic
(2) For exit stack gas for temperature
greater than 125 degrees Fahrenheit. The following calculations shall be used
for exit stack gas for temperatures greater than 125 degrees Fahrenheit.
(A) The H[sub]2[/sub]SO[sub]4[/sub] ambient
air level of 80 ug/M[sup]3[/sup] for one hour is used.
Attached
Graphic
(B) To
plot Graph V, assume a basic stack height of 100 feet and an exit velocity of
20 feet/second. Let stack gas temperature vary with stack diameter.
(3) Examples. The following are
examples of stack emission calculations.
(A)
Example 1. (Temperature of stack gas less than 125 degrees Fahrenheit.) How
many pounds/hour of H[sub]2[/sub]SO[sub]4[/sub] can be discharged from a 200
foot stack having a four foot exit diameter (ID) and a 30 feet/second exit gas
velocity? The temperature of the exit gases is 100 degrees Fahrenheit.
Solution.
(i) The ratio of stack diameter to
100 feet is 4/100 = 0.04.
(ii)
Enter ordinate of Graph IV with 0.04; go horizontally to intersection of 30
feet/second velocity curve. At this intersection read on the abscissa 17
pounds/hour. This is the permitted value for a 100 foot stack.
(iii) Correct emissions for a 200 foot stack.
Enter Graph I at 200 feet and obtain correction factor of 2.3. Thus the
emissions become 17 x 2.3 = 39 pounds/hour.
(B) Example 2. (Temperature of stack gas
greater than 125 degrees Fahrenheit.) How many pounds/hour of
H[sub]2[/sub]SO[sub]4[/sub] can be discharged from a 200 foot stack having a
four foot exit diameter (ID) and a 30 feet/second exit gas velocity? The
temperature of the exit gases is 400 degrees Fahrenheit. Solution.
(i) Enter ordinate of Graph V with 400; go
horizontally to intersection of four foot diameter and read on abscissa 26
pounds/hour emission. This is the permitted value for a 100 foot stack and exit
velocity of 20 feet/second.
(ii)
Correct for stack height. Thus, 200/100 = 2. We now have 26 x 2 = 52
pounds/hour.
(iii) Correct for
stack exit velocity of 30 feet/second. This is a direct ratio and becomes 30/20
= 1.5. The emission now is 52 x 1.5 = 78 pounds/hour.
Attached
Graphic
