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Continuous Emissions Monitoring systems (CEMs) have become an important part of the industrial, municipal, and infectious waste incineration industry. With the promulgation of stringent emissions limits and source emissions monitoring requirements, and with permit approvals and operating penalties dependent upon the accuracy and dependability of the CEM, most new and existing incineration facilities now recognize that the CEM system can often mean the difference between success and failure. Since the early 1980's, extractive sampling systems have been the technology of choice, due to the inherent difficulties in sampling from a typical incineration process. Some of these difficulties include: high temperatures, high particulate levels (dependent on the type of waste fuel being fired), the presence of acid-gases in the sample stream, high moisture levels, and wide fluctuations in the incineration process resulting in significant variations in emissions levels and sampling conditions. In addition, the requirement for lower emissions levels has resulted in the use of new control technologies which can often negatively affect the performance of a CEM system. A good example is the use of ammonia injection (either Selective Catalytic Reduction or Thermal DeNOx processes) for the control of NOx emissions, which results in an ammonia slip which can potentially interfere with the CEM measurement of either NOx or SO2 emissions. Extractive sampling systems, when designed to meet the specific application requirements and when assembled of reliable components constructed of the proper materials, have been proven in most difficult incineration installations. Extractive sampling systems offer the flexibility to overcome even the inherent difficulties usually encountered with industrial, municipal and infectious waste incinerators.
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