| (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 (H2SO4 ).
(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
H2SO4 , then
both upwind and downwind samples will be taken. The concentration
of H2SO4 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 H2SO4 concentrations from stack samples and measurements.
The maximum allowable H2SO4 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 H2SO4 ambient air level of 80 ug/M3 for one hour is used.
Attached Graphic
(B) To plot Graph IV, assume a basic stack height of
100 feet and plot
Attached Graphic
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 H2SO4 ambient air level of 80 ug/M3 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
2SO4 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 H2
SO4 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
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