Using threshold values to continuously evaluate how effectively electrostatic precipitators operate

Abstract

The increased use of biomass as a fuel in energy production can reduce CO2 emissions in this sector. Fossil fuels can thus be replaced, especially in the field of heat supply. However, this should not occur at the expense of increased particulate matter emissions, which is why electrostatic precipitators (ESPs) are used. Continuous monitoring of the ESP is called for in the European Union Directive 2015/2193 for medium combustion plants (MCP), which applies to plants with a nominal heat output of between 1 and 50 MW. A monitoring methodology based on the precipitator parameters current (I) and voltage (U) was presented in an earlier presentation. The work at hand follows up on the previous findings and presents an alternative methodology that aims to define the effectiveness of the ESP via threshold values for U and I. It is shown that two types of misinterpretation of the operation may occur when threshold values are defined. The operating condition could be regarded as effective via the methodology, although the measurement proves ineffective in operation and the opposite error also occurs. The statistical evaluation of the frequency of errors is intended to help the legislative authorities determine the threshold values in a reasonable way. In addition, checks are made as to whether it is possible to verify the operation of the combustion system via the flue gas temperature. The operating times of the combustion are essential, as they define the operating times required by the precipitator. In this context, statistical evaluations are made to determine which plant-specific threshold value could be useful. The aim is to test the effective operation of the separator from readily available data at all times. These considerations could form the basis for developing a uniform methodology to ensure compliance with the legal requirements.