United States Environmental Protection Agency Air and Energy Engineering Research Laboratory Research Triangle Park, NC 27711 Research and Development EPA/600/S8-88/069 July 1988 ^EPA Project Summary Construction and Operation of a 10 CFM Sampling System with a 10:1 Dilution Ratio for Measuring Condensable Emissions William J. Steele, Ashley D. Williamson, and Joseph D. McCain This report describes a trans- portable sampling apparatus de- signed to sample incineration sources at municipal and hazardous waste disposal facilities,and to provide non-contaminated samples of condensable materials. The sam- ple gas, at a flowrate of 10 cfm (283 Ipm), passes through a modified Source Assessment Sampling Sys- tem (SASS) cyclone and is then diluted with clean air at 100 cfm (2830 Ipm) by a novel, perforated cone assembly. Rapid uniform dilu- tion takes place through the vigorous mixing of the sample and clean air streams in the dilution chamber. The resultant gas, cooled to approx- imately atmospheric conditions, is passed'through a mixing section that provides a residence time of approximately 3 sec. The resulting aerosol particles are collected on a Teflon-coated glass-fiber filter. These solids, along with those col- lected in the cyclone, are subse- quently provided for chemical and biological assay analysis. This Project Summary was developed by EPA's Air and Energy Engineering Research Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction The primary design objective of this apparatus was to provide (for bioassay) non-contaminated samples of con- densable materials from stack discharges at municipal incinerators and hazardous waste disposal facilities. Two opposing design constraints were: (1) to provide sufficient quantities of particulate matter within a reasonable sampling time (i.e.,<1 day), and (2) to provide a portable instrument that could be operated at various sites. For microbial mutagenicity (Ames) assays, sufficient particulate to obtain 10-100 mg of extractable organic material is desirable. This resulted in the design of a 10 cfm (283 Ipm) sampling system with a 10:1 dilution ratio. System Description The main flow paths within the dil- ution system are: 1) dilution air, 2) sam- ple gas, 3) diluted gas, and 4) outlet gas. The dilution air is extracted from the ambient atmosphere and conditioned with a condenser system, High Efficiency Particulate Air (HEPA) filter, and a charcoal bed. A heater raises the dilution air temperature to 70°F (21 °C) when necessary. An in-line orifice is used to measure the dilution air flowrate (nominally 100 cfm or 2830 Ipm). The sample gas is extracted from the stack through a 3/4-in. (1.9 cm) ID glass-lined probe. The probe introduces ------- the stack gas to a modified Source Assessment Sampling System (SASS) cyclone which has a D$Q of 1.8 ^m for a 10 cfm flowrate at about room temperature (75°F or 24°C). The probe and cyclone are heated to maintain the sample gas at the existing flue gas temperature. The sample gas is diluted by the dilution air at a 10:1 ratio in the dilution cone. The sample gas is introduced at the throat of the cone, and the dilution air is forced through the perforations on the outer surface of the cone. The combined gas (called diluted gas) enters a dwell chamber where a residence time of approximately 3 sec allows for the formation of condensable emissions. The resulting paniculate materials are then collected on a Teflon-coated glass- fiber filter. An outlet transform below the filter directs the filtered gas to the exhaust pump. The flow of the outlet gas is measured by an orifice upstream of the pump. The support assembly for the dilution system provides a cradle for supporting the dilution manifold and the associated probe. The cradle can be adjusted vertically to position the probe at the selected sampling port. The critical temperatures and pressures of the dilution system are regulated by the control and monitoring assembly. System Assembly The first step in assembling the system is to construct the dilution manifold inside the support structure. Three wooden cradles support the assembled dilution manifold; heavy- duty elastic cords hold the transform on the cradles. Once the manifold is supported, the outlet transform may bo removed and the filter placed in the recessed surface of the filter flange. The cyclone may then be attached to the face of the diluter. The rear of the cyclone is supported with a clamp attached to a front rail of the support structure. A second clamp supports one end of the probe; this clamp is attached to a side rail for horizontal probe access or to a rail directly under the cyclone for vertical probe access. The HEPA filter and charcoal bed used to condition the dilution air should be replaced prior to each test. During a run, the probe and cyclone should be kept as near to stack temperature as feasible. The cyclone should not be heated above 375°F (191°C) to avoid damaging the internal finish. Care should be used during leak tests and sampling to apply and release pressures and/or vacuums gradually to avoid rupturing the sample filter. At the completion of a run, the sample filter should be handled carefully (surgical gloves are suggested) and sealed in a glass or Teflon container to prevent external contamination William J. Steele, Ashley D. Williamson, and Joseph D. McCain are with Southern Research Institute, Birmingham, AL 35255-5305. Sharon L No/en is the EPA Project Officer (see below). The complete report, entitled "Construction and Operation of a 10 CFM Sampling System With a 10:1 Dilution Ratio for Measuring Condensable Emissions," (Order No. PB 88-198 551/AS; Cost: S12.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Air and Energy Engineering Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Official Business Penalty for Private Use $300 EPA/600/S8-88/069 ------- |