(ii) The statement in § 63.1257(d)(2)(i)(B) that "the partial pressure of HAP shall be assumed to be 25 percent of the saturated value if the purge flow rate is greater than 100 scfm" does not apply. For the purposes of this subpart, multiply the HAP partial pressure in Equation 12 of 40 CFR part 63, subpart GGG by a HAP-specific saturation factor determined in accordance with Equations 1 through 3 of this section. Solve equation 1 of this section iteratively beginning with saturation factors (in the right-hand side of the equation) of 1.0 for each condensable compound. Stop iterating when the calculated saturation factors for all compounds are the same to two significant figures for subsequent iterations. Note that for multi-component emission streams, saturation factors must be calculated for all condensable compounds, not just the HAP. View Image
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where:
S1 = saturation factor for individual condensable compounds in the emission stream
Pi = partial pressure of individual condensable compounds in the emission stream calculated using Raoult's Law or other appropriate methods
PT = pressure of the vessel vapor space
A = surface area of liquid
V = purge flow rate as used in Equation 12 of 40 CFR part 63, subpart GGG
Visat = volumetric flowrate of condensable compounds in the emission stream
Ki = mass transfer coefficient of individual condensable compounds in the emission stream
Ko = mass transfer coefficient of a reference compound (e.g., 0.83 cm/s for water)
Mo = molecular weight of reference compound (e.g., 18.02 for water)
Mi = molecular weight of individual condensable compounds in the emission stream
n = number of condensable compounds in the emission stream