Resumo:
The principal sources of atmospheric polluting emissions of sugar/alcohol units are the
steam boilers that use sugar cane bagasse as fuel. As a result of the combustion their release
carbon oxides, (CO and CO2), nitrogen oxides (NOx) and particulate matter. By using an
atmospheric polluting dispersion study, this work aims at determining the impact of the
emission of nitrogen oxides released by a Sugar and Alcohol Plant on the quality of the air in
the surrounding area. The case of Barra Grande Plant located in the state of São Paulo, Brazil,
will be studied. The formation and control mechanisms are assessed based on the
measurements of the NOx concentrations in the combustion products. The atmospheric
dispersion study was carried out by using the ISCST3 (Industrial Source Complex Short Term
version 3) dispersion model, recommended by USEPA (United States Environmental
Protection Agency), based on hour meteorological data of the place within the period of 2002.
Two types of analyses regarding the quantity of NOx present in the atmosphere will be shown.
The first one considers the total conversion of NOx into NO2 as it is recommended by most
environmental agencies. In this case, the use of technologies aiming at the control and
prevention of NOx emissions could be necessary. In turn, the second analysis considers the
Janssen Factor, which describe the conversion of NOx into NO2 and NO, considering the local
atmospheric characteristics and the ozone concentration (O3), approach that was defined as
the most realistic one in this work. The results of the dispersion study are presented as NOx
iso-concentration curves, based on which the conclusions about the appropriate control and
prevention technologies are drawn.
