Abstract:
The Emission Limit Values (ELVs) for the Particulate Matter in the steel industry are defined by environmental legislation, requirements of the competent authorities, and/or environmental policies of the company, reaching 5 mg/Nm3. The implementation of the dedusting equipment to reach ELVs are always accompanied by performance test, based on gravimetric measurements of isokinetically obtained samples, which are used to demonstrate the abiding to the project specifications, as well as parametrisation of the Continuous Emission Monitoring systems. The measurements based on methods defined in the 1970s to 1990s, have shown questionable results for low level emissions of particulate matter. And, as a consequence, in EU and USA, new methods have been promulgated specific for such case. Although the performance of gravimetric tests is relatively common, when applied to low level emissions of particulates, special precautions are needed in order to ensure that the uncertainties do not invalidate the result, since in some cases the reproducibility reached approximately 50% of the measured value. It is our goal to analyse the main factors which influence the repeatability of the measurement and, based on the hands-on experience, present the practices which need to be implemented in order to increase the result reliability.