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Show was performed under the CCT program. To obtain information on the fate of hazardous air pollutants and to facilitate mass balances, samples of all significant input and output streams around the boiler and air pollution controls are collected and analyzed. To ensure that data for each stream are comparable to each other, simultaneous sampling of all streams should be performed. Usually, simultaneous sampling for all substances is not practical due to space limitations. This can be resolved by sampling like substances simultaneously. For example, at the Cardinal plant EER sampled for all organic substances on three test days followed by three days for testing of all inorganic substances. This maintains the validity of data comparisons. Close attention to process operation and monitoring also is a key part of comprehensive assessments. Because of the long times required to collect all samples, the process must operate at steady, repeatable, and known conditions for all sampling activities. It is critical to review - operation with plant operators and managers to ensure that samples are collected under representative conditions and that unnecessary delays are avoided. In complex programs such as the Cardinal program, a large test crew (up to 27 people) were required on-site. Obviously the cost of delays due to process upsets becomes very expensive with such a large on-site team and good coordination and planning can minimize them. SAMPLING AND ANALYTICAL CHALLENGES There are a number of differences in flue gas characteristics of coal fired boilers that have implications on the application of test methods designed for other types of sources. Table 2 compares typical flue gas characteristics for municipal, hazardous, and medical waste incinerators to coal fired boilers. The most striking differences are in the physical size of the ducts, particulate concentration, and S02 concentration which can be much greater than typical waste combustion systems. Because of the large duct dimensions in coal fired plants, quartz probes cannot be used without breaking. This can generally be resolved by using Teflon tubing for the probe liner material; however, with very long probes such as EER used for the Cardinal plant (up to 30 feet), differential thermal expansion of the Teflon liner can push the nozzle out of the probe or the liner back into the filter housing. Also, use of Teflon is limited to maximum temperatures of about 400- 450°F before softening occurs. When sampling at the inlet to particulate control devices to determine removal efficiencies, very high particulate loadings can complicate sampling. Use of a cyclone upstream of the particulate filter can minimize filter plugging problems when filters are 7 |