The Electrostatic Precipitator External Parameters at the Heart of Dust Collection Efficiency Performance: Coal Characteristics, Combustion Quality and SCR Chemical Process
V. Arrondel1, G. Bacchiega2, and M. Hamlil1
1EDF R&D, France
2I.R.S. s.r.l., Italy
Abstract— Since January 1st, 2008, the coal power plants are subject to new stricter European Environmental Regulations. To fulfil these new stakes, new and existing units were equipped with air pollution control devices such as denitrification system (for example Selective Catalytic Reduction processes) in addition to the electrostatic precipitators (ESP) and wet-flue gas desulphurization (wet-FGD). The electrostatic filter particle collection process performances mainly depend on: the residence time of dust inside the ESP, the physico-chemical properties of dust (size, chemical composition, resistivity), the voltage applied to the dust collector. Only this last point is linked to the ESP itself while the other two depend on other external parameters. This article focuses on these external parameters and makes the analyses of their impacts on the collection performances. In particular, we describe and analyse the impact of : (1) coal characteristics through more than 500 reliable coal chemical analyses (from South Africa, Australia, China, Poland, Indonesia, Norway, Poland, Russia, USA coal supplies), (2) residence time, resistivity and collection performances of the 500 coals analysed through software simulation, and (3) SCR process impacts on the resistivity and the particle size through SO2 oxidation into SO3 as well as the possible production of ammonia sulphate and bi-sulphate species.
Keywords— Coal characteristics, ESP efficiency, SCR, electrostatic precipitators, resistivity, combustion, dust, PM10, back-corona