ICAC Proposed Conditional Test Method (CTM-042)*
Use of Flame Ionization Detector-Methane Cutter Analysis Systems for VOC Compliance Testing of Bakeries
Performance testing of volatile organic compounds (VOC) destruction devices such as thermal oxidizers and catalytic oxidizers require simultaneous measurements of non-methane hydrocarbons (NMHC) in the gas streams entering and exiting the destruction device. In the past, continuous total hydrocarbon measurements employing testing protocol in accordance with U.S. EPA Test Method 25A (Gaseous Organic Concentration - Flame Ionization) has been combined with laboratory analysis of grab samples taken hourly. This approach has been demonstrated to be labor intensive, costly and does not provide real-time measurements necessary to evaluate the performance of the thermal or catalytic oxidizer.
Use of this method is limited to measuring VOC emissions from bakeries. The purpose of this Conditional Test Method (CTM) is to provide an alternate method for making real-time non-methane hydrocarbon measurements for providing immediate information regarding performance of the VOC destruction device. This method describes the use of a hot flame ionization detector (FID) based instrument equipped with a catalytic methane cutter in conjunction with U.S. EPA Test Method 25A to provide real-time differential measurement of total hydrocarbons, methane and by difference non-methane hydrocarbons.
This CTM is directly applicable to large commercial bakeries. The measurement of VOC’s in bakeries is required to verify air pollution control equipment destruction efficiency as required by various state regulations. The large majority of these state regulations are State Implementation Plan (SIP) driven. A minority of states have “State Only” legislation requiring oxidizes, and testing of them, on bakeries.
Extensive commercial data has been gathered from large commercial bakeries, where exhaust gases from ovens baking bread, crackers and other yeast products are tested. These exhaust streams typically contain ethanol in concentrations of 1,000 to 5,000 ppm, methane in concentrations of 50 to 1000 ppm and moisture at 2 to 15%. A catalytic oxidizer on this application will destroy 95-99% of the non-methane hydrocarbons, reducing the ethanol to concentrations of 10 ppm to 250 ppm in the oxidizer exhaust. The other compounds will virtually maintain their concentrations. Due to the large amounts of moisture and the water solubility of the non-methane hydrocarbon, condensation must be avoided. The relatively large amount of methane to non-methane hydrocarbon, especially in the oxidizer exhaust, makes it more important to make this measurement by one technique.
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