INDUCTIVELY-COUPLED ARGON PLASMA CONTINUOUS EMISSIONS MONITOR FOR HAZARDOUS AIR POLLUTANT METALS

The design and operation of instrumentation capable of continuous, rea l-time detection and monitoring of hazardous air pollutant metals in t he effluent of boilers, incinerators, and furnaces is reported. A comm ercially available inductively coupled argon plasma spectrometer, modi fied for introduction of sample air, provides sensitivity for several metals comparable to that of EPA-approved manual methods, with a measu rement frequency of 30-60 measurements/h. Achievable detection limits for the present list of hazardous air pollutant metals range from 0.1 to 20 mu g/dry standard cubic meter; a capability unmatched by competi ng CEM technologies. To ensure that a representative sample is obtaine d at all times, air is isokinetically extracted from a stack or duct b y an automated system. An innovative sampling interface combines conti nuous sample extraction at the relatively high and often variable flow rates required for isokinetic conditions with periodic introduction o f aliquots of sample air and reference air at the constant and low flo w rates required for injection into the argon plasma.