Abstract: Despite worldwide calls to reduce its use, coal continues to be widely used for thermoelectric generation. Based on this, using it in a way that minimizes its harmful effects on the environment and the health of the population is essential. As it contains a significant percentage of sulfur in its composition, Brazilian coals after conversion must have their emissions strictly controlled in order to comply with legislation and mitigate their effects on the environment. In this way, experimental tests were carried out on a bench scale with the combustion of Brazilian coal from the state of Paraná using limestone to reduce sulfur oxides from the exhaust gas stream. To this end, a bubbling fluidized bed combustor was used where tests were carried out in addition to burning coal without adding limestone as a basis for comparison, as well as mixtures containing a Ca/S molar ratio in the order of 2, 3 and 4. The influence of temperature on sulfur reduction considering typical to the technology values were applied too. The gas compositions during combustion testes were obtained through a portable gas analyzer and the thermal behavior of the fuel was carried out using a thermogravimetric analyzer (TGA). Additionally, the behavior of limestone in relation to its temperature increase was evaluated using thermogravimetric tests. From the tests carried out, it was found that the limestone used showed degradation peaks below 790°C on a thermobalance. This phenomenon could be confirmed in bench combustion tests, since for milder temperatures (around 815°C) the sulfur reduction was greater than those tested at higher temperatures (around 850°C). In terms of sulfur reduction, molar ratios 3 and 4 achieved reductions that comply with current legislation for the state of Paraná while ratio 2 did not reach values appropriate to the legislation.

Keywords: Desulfurization, Combustion, Fluidized Bed, Brazilian Coal, Limestone.