Continuous Emission Monitoring, 3rd Edition

CHAPTER 5EXTRACTIVE SYSTEM ANALYZERS

The choice of gas analyzers for an extractive CEM system is important because some analytical techniques are more appropriate than others in a source application or system design. The total system must be considered; any system evaluation must be made on both the analyzers used and the extractive conditioning system itself. Chapter 3 reviewed methods for extracting, transporting, and conditioning flue gases for analysis. This chapter discusses the types of instrumentation used to determine gas concentrations after the flue gas has been properly conditioned for analysis.

Many problems occur when monitoring emissions from stationary sourceas; one of the major problems is that the pollutant gas must be analyzed among other stack gas constituents. The possibility of other gases interfering in the measurement process is great, and many approaches have been developed to avoid such interferences. As a result, a variety of spectroscopic and electroanalytical measurement techniques and new technologies that enable the measurement of gas concentrations at part per billion levels have been developed and applied.

Table 1‐2 summarizes the current commercially marketed techniques used in source monitoring analyzers. Table 5‐1 gives the major categories of methods used in extractive system analyzers. Extractive analyzers use techniques from all of these categories, whereas in‐situ monitors use only spectroscopic absorption or electrochemical methods. Extractive ...