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246 Lawrence K. Wang et al.

D = ft /lb
3
w
3
where D = D is the density of emission (lb/ft ), P is the pressure of the emission
w
stream (1 atm), M is the molecular weight of the specific pollutant gas (18 lb/lb-mol),
3
R is the gas constant (0.7302 atm-ft /lb-mol °R), and T = T is the temperature of the
e,s
gas (°R).
Substituting into Eq. (29) yields
Q = cfm
w
The saturated emission stream flow rate is determined by substituting into Eq. (29):
Q = acfm
e,s
G. Permit Application for Submission
The results of this exercise, with supporting data, are summarized in the following
table. Note P (estimated pressure drop) versus the observed pressure drop for this
v
Venturi scrubber. When estimated and reported results differ significantly, such dis-
crepancies may be the result of the following:
1. Use of an incorrect performance curve
2. Disagreement between required and observed removal efficiencies
This will necessitate a discussion of system details (design and operational proce-
dures) with the applicant. If the estimated and operational pressure losses are in
agreement, one may assume that both design and operation of the Venturi scrubber are
satisfactory based on the assumptions used in this handbook.

Calculated value Observed value
Particle mean diameter, D
p
Collection efficiency, CE
Pressure drop across venture, P
v
Example 14
This example uses an instance in which a municipal incinerator is conducting an investigation
evaluating the usefulness of the Venturi scrubber (see Fig. 1c) to solve an air pollution con-
trol issue. The Venturi is one of several possible methods that could be used to treat this
air emission stream (see Table 15). Using the Calculation Sheet for Venturi Scrubbers from
Example 13, this study will proceed according to the following:
A. Gather the pertinent pollutant characterization data.
B. Estimate the Venturi scrubber pressure drop.
C. Decide the needed fabrication material.
D. Determine saturated gas flow rate for Venturi scrubber sizing purposes.
E. Consult with the appropriate regulatory authorities (federal, state, and local) how the
agency will evaluate the incinerator’s Venturi scrubber permit application.
Solution

A. HAP Characteristics—needed data:
Because a Venturi scrubber is one of the selected control techniques for the theoreti-
cal municipal emission stream, the pertinent data for these procedures are taken from
the HAP Emission Stream Data Form (Table 15).