Potencialização da cogeração de energia em uma usina sucroenergética por meio do aproveitamento do palhiço da cana-de-açúcar, eletrificação de acionamentos e redução da umidade do bagaço
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Data
2017-12-27
Autores
Santos, Paulo Sérgio Barbosa dos
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Universidade Estadual Paulista (Unesp)
Resumo
A bioenergia, energia da biomassa, possui um papel fundamental na matriz elétrica brasileira, sendo que o setor sucroenergético é merecedor de destaque com a produção de excedentes de energia elétrica. No entanto, até bem pouco tempo atrás haviam entraves para o incremento na cogeração nesse setor devido à limitação a 30 MW da exportação da energia incentivada através da concessão de descontos nas tarifas de transmissão e distribuição da energia às usinas. Com a atualização recente da legislação, esse limite foi ampliado para 50 MW para as usinas já existentes e para 300 MW para novos projetos, como forma de incentivo para a implantação de novos investimentos. Diante deste contexto, no presente trabalho foram analisadas tecnologias para potencializar a cogeração de energia, a partir da queima da biomassa da cana-de-açúcar, no setor sucroenergético, a fim de possibilitar ganhos com a venda de excedentes de energia elétrica. Para tanto, foi estudado o incremento do uso da palha como combustível, por meio da regulagem dos extratores da colhedora e transporte da mesma junto com a cana, nas proporções de 4, 6, 8, 10 e 12 % em relação à cana entregue na usina e posterior passagem por sistema de limpeza a seco antes da queima na caldeira. Além disso, foi realizada a eletrificação dos acionamentos dos equipamentos que operavam com turbinas a vapor de baixa eficiência e alto consumo de vapor. Neste trabalho também foi verificado o efeito do uso de camisas de alta drenagem (rolo Lótus), a fim de reduzir os impactos do fenômeno da reabsorção do bagaço e, consequentemente, da umidade do bagaço, resultando em ganhos no Poder Calorífico Inferior (PCI), melhorando, assim, a qualidade do combustível queimado nas caldeiras. Por fim, foram realizadas as análises econômicas dos casos de cogeração propostos, através de técnicas de Valor Presente Líquido (VPL) e Taxa Interna de Retorno (TIR), afim de verificar os casos com viabilidade econômica, cujos resultados demonstraram é necessário a venda do MWh no mínimo a R$ 180,00.
Bioenergy, biomass energy, has a fundamental role in the Brazilian electricity matrix, and the sucroenergy sector is worthy of note with the production of surplus electricity. However, until very recently there were obstacles to an increase in cogeneration in this sector due to the limitation of 30 MW in energy exports encouraged through the concession of discounts on energy transmission and distribution tariffs to the mills. With the recent updating of the legislation, this limit was extended to 50 MW for existing plants and to 300 MW for new projects, as an incentive for the implementation of new investments. In view of this context, in the present work, technologies for potentializing energy cogeneration, from the burning of sugarcane biomass, in the sugar-energy sector, were introduced in order to make gains from the sale of surplus electricity. In order to do so, the increase of the use of straw as fuel was studied by regulating the extractors of the harvester and transporting it together with the cane, in the proportions of 4, 6, 8, 10 and 12% in relation to the sugar cane delivered in the and subsequent passage through the dry cleaning system before burning in the boiler. In addition, the study was complemented with the electrification of the drives of the equipment that operated with steam turbines of low efficiency and high consumption of steam. In this work the effect of the use of high drainage liners (Lotus roll) was also verified, in order to reduce the impacts of the reabsorption of bagasse and, consequently, bagasse moisture, resulting in gains in the Lower Calorific Power (LCP), thereby improving the quality of the fuel burned in the boilers. Finally, the economic analyzes of the proposed cogeneration cases were carried out using Net Present Value (NPV) and Internal Rate of Return (IRR) techniques, in order to verify cases with economic viability, the results of which showed that it is necessary to sell the MWh for a minimum of R$ 180,00
Bioenergy, biomass energy, has a fundamental role in the Brazilian electricity matrix, and the sucroenergy sector is worthy of note with the production of surplus electricity. However, until very recently there were obstacles to an increase in cogeneration in this sector due to the limitation of 30 MW in energy exports encouraged through the concession of discounts on energy transmission and distribution tariffs to the mills. With the recent updating of the legislation, this limit was extended to 50 MW for existing plants and to 300 MW for new projects, as an incentive for the implementation of new investments. In view of this context, in the present work, technologies for potentializing energy cogeneration, from the burning of sugarcane biomass, in the sugar-energy sector, were introduced in order to make gains from the sale of surplus electricity. In order to do so, the increase of the use of straw as fuel was studied by regulating the extractors of the harvester and transporting it together with the cane, in the proportions of 4, 6, 8, 10 and 12% in relation to the sugar cane delivered in the and subsequent passage through the dry cleaning system before burning in the boiler. In addition, the study was complemented with the electrification of the drives of the equipment that operated with steam turbines of low efficiency and high consumption of steam. In this work the effect of the use of high drainage liners (Lotus roll) was also verified, in order to reduce the impacts of the reabsorption of bagasse and, consequently, bagasse moisture, resulting in gains in the Lower Calorific Power (LCP), thereby improving the quality of the fuel burned in the boilers. Finally, the economic analyzes of the proposed cogeneration cases were carried out using Net Present Value (NPV) and Internal Rate of Return (IRR) techniques, in order to verify cases with economic viability, the results of which showed that it is necessary to sell the MWh for a minimum of R$ 180,00
Descrição
Palavras-chave
Palha, Cogeração, Eletrificação, Rolo Lótus, Energia, Straw, Cogeneration, Electrification, Lotus Roll, Energy