Table 3 to Subpart AA of Part 63 - Monitoring Equipment Operating Parameters

Table 3 to Subpart AA of Part 63 - Monitoring Equipment Operating Parameters

You must . . .	If . . .	And you must monitor . . .a	And . . .a
Absorbers (Wet Scrubbers)
Install a continuous parameter monitoring system (CPMS) for liquid flow at the inlet of the absorber	Your absorber is designed and operated with pressure drops of 5 inches of water column or more; and you choose to monitor only the influent liquid flow, rather than the liquid-to-gas ratio	Influent liquid flow
Install CPMS for liquid and gas flow at the inlet of the absorberb	Your absorber is designed and operated with pressure drops of 5 inches of water column or less; or Your absorber is designed and operated with pressure drops of 5 inches of water column or more, and you choose to monitor the liquid-to-gas ratio, rather than only the influent liquid flow, and you want the ability to lower liquid flow with changes in gas flow	Liquid-to-gas ratio as determined by dividing the influent liquid flow rate by the gas flow rate through the absorber. The units of measure must be consistent with those used to calculate this ratio during the performance test	You must determine the gas flow rate through the absorber by: Measuring the gas flow rate at the absorber inlet or outlet; Using the blower design capacity, with appropriate adjustments for pressure drop;c or Using a regression model.d
Install CPMS for pressure at the gas stream inlet and outlet of the absorber	Your absorber is designed and operated with pressure drops of 5 inches of water column or more	Pressure drop through the absorber	You may measure the pressure of the inlet gas using amperage on the blower if a correlation between pressure and amperage is established
Sorbent Injection
Install a CPMS for flow rate		Sorbent injection rate
Install a CPMS for flow rate		Sorbent injection carrier gas flow rate
Wet Electrostatic Precipitators
Install secondary voltage meter	You control mercury or metal HAP (particulate matter) using an electrostatic precipitator	Secondary voltage

^a To monitor an operating parameter that is not specified in this table (including process-specific techniques not specified in this table to determine gas flow rate through an absorber), you must request, on a site-specific basis, an alternative monitoring method under the provisions of 40 CFR 63.8(f).

^b For new sources that commence construction or reconstruction after August 19, 2015, the compliance date is immediately upon startup. For existing sources, and new sources that commence construction or reconstruction after December 27, 1996, and on or before August 19, 2015, if your absorber is designed and operated with pressure drops of 5 inches of water column or less, then the compliance date is August 19, 2018. In the interim, for existing sources, and new sources that commence construction or reconstruction after December 27, 1996, and on or before August 19, 2015, with an absorber designed and operated with pressure drops of 5 inches of water column or less, you must comply with one of the following: (i) The monitoring requirements in this Table 3 for absorbers designed and operated with pressure drops of 5 inches of water column or less; (ii) the applicable monitoring provisions included in a permit issued under 40 CFR part 70 to assure compliance with subpart AA; (iii) the applicable monitoring provisions of an Alternative Monitoring Plan approved pursuant to § 63.8(f); or (iv) install CPMS for pressure at the gas stream inlet and outlet of the absorber, and monitor pressure drop through the absorber.

^c If you select this option, then you must comply with § 63.608(e). The option to use blower design capacity is intended to establish the maximum possible gas flow through the absorber; and is available regardless of the location of the blower (influent or effluent), as long as the gas flow rate through the absorber can be established. Establish the minimum liquid-to-gas ratio operating limit by dividing the minimum liquid flow rate to the absorber (determined during a performance test) by the maximum possible gas flow rate through the absorber (determined using blower design capacity).

^d If you select this option, then you must comply with § 63.608(f). The regression model must be developed using direct measurements of gas flow rate, and design fan curves that correlate gas flow rate to static pressure (i.e., fan suction pressure) and brake horsepower of the blower. You must conduct an annual regression model verification using direct measurements of gas flow rate to ensure the correlation remains accurate. Direct measurements of gas flow rate used to develop or verify regression models may be collected during, or separately from, the annual performance testing that is required in § 63.606(b).

[80 FR 50436, Aug. 19, 2015, as amended at 82 FR 45199, Sept. 28, 2017]