Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 17

Alternative approaches to emissions monitoring have been developed that do not require the use of analytical instrumentation, but rely instead on inputs from process sensors, such as thermocouples, pressure transducers, and fuel flow meters. Data from these sensors can be used in a variety of ways in environmental regulatory programs. The parameter information can be either used directly as a surrogate to substitute for concentration‐based emissions data or it can be incorporated into a model to predict emissions.

U.S. regulatory programs have long used parameter data such as pressure drop or temperature to monitor the performance of emission control equipment. The parameter data has been used either as a regulatory trigger to initiate enforcement action directly or as an indicator of noncompliance with permit conditions. Control equipment and unit operational parameters can also be used directly in continuous parameter monitoring systems (CPMS) as part of a continuous monitoring system (CMS). This regulatory approach does not require the use of continuous emission monitoring systems although a CEM system can be a part of a CMS. The U.S. air toxics standards make extensive use of this method.

A more recent approach has been used to develop emission models based on process parameter data. Models are developed by first correlating parameter data to emissions data. An initial study is performed by varying and monitoring process and control equipment parameters while monitoring flue gas emissions using reference methods or CEM systems. One can then correlate the data using engineering calculations, least squares methods, or neural net techniques to develop a model that “predicts” emissions from parameter data. Such predictive emission monitoring systems (PEMS) employ from 3 to 20 input parameters and have been applied to a variety of sources. They are most successful on sources with minimal variation in fuels and operating conditions.