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Publication
Aproveitamento dos gases de exaustão do forno para produção de energia elétrica na BA Vidro
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Abstract(s)
O presente trabalho foi realizado na empresa BA Vidro – Unidade de Avintes, no âmbito
da dissertação/Estágio do mestrado em Engenharia Química – Otimização Energética na
Indústria Química.
O objetivo principal deste trabalho foi dimensionar um ciclo de Rankine orgânico (CRO)
para produzir energia elétrica, a partir do aproveitamento dos gases de exaustão
provenientes de um dos fornos de fusão da empresa.
Os gases de exaustão encontram-se respetivamente à temperatura de 433,3°C e a 296,5
°C, antes e após a sua passagem pelo filtro eletrostático. Dos fluidos orgânicos
estudados, o tolueno foi o que apresentou uma maior produção de energia elétrica, cerca
de 605 kW com a fonte quente a 296,5°C e 768,9 kW com a fonte quente a 433,3°C. Para
este fluido, e para a mesma produção de energia elétrica, foi avaliada a eficiência térmica
do ciclo de Rankine simples e com regenerador, tendo-se obtido valores de eficiência de
24,7 %, e 29,3 %, respetivamente.
A energia elétrica produzida correspondeu a 48 % do consumo total do forno, permitindo
chegar a uma poupança anual média de 127.755 €. No entanto a análise económica desta
medida não foi efetuada, porque não foi possível obter informação relativa ao orçamento
do CRO em tempo útil.
Paralelamente a este estudo foram analisadas duas medidas relativas à poupança de gás
natural consumido na caldeira. A primeira medida foi a alteração da temperatura das
águas sanitárias de 87 °C para 70 °C. Esta medida não implica qualquer investimento e
gera uma poupança anual de 3.143 €. Na segunda medida estudou-se a viabilidade da
implementação de um permutador de calor de fluxo cruzado para o aquecimento das
águas sanitárias até 70 °C, a partir dos gases de exaustão resultantes da fusão do vidro.
Neste caso o orçamento do equipamento variou entre 3.500 € e 15.000 €. Com uma
poupança anual de 11.093 €, o período de recuperação do investimento obtido variou
entre os 0,32 e os 1,4 anos, o que revelou que a instalação do permutador é viável em
qualquer uma das situações apresentadas.
This report refers to the work developed in the company BA Vidro – Unidade de Avintes, in the frame of the course “Dissertação/Estágio” for the obtention of Master Degree in Chemical Engineering – Energy optimization in the Chemical Industry. The main goal was the design of an organic Rankine cycle (ORC) in order to produce electricity, using the residual heat from exhaust gases of a glass furnace. The exhaust gases are at 433.3°C and 296.5 °C, before and after they pass by the electrostatic filter. Among the considered fluids, toluene showed the highest electrical energy production, around 605 kW with the heat source at 296.5°C and 768.9 kW with the heat source at 433.3°C. Using this fluid, and for the same power output, the termal efficiencies obtained were 24,7 %, and 29,3 %, for an ORC with and without recuperator, respectively. The production of electricity is 48 % of the total consumption of the furnace, allowing an average annual savings of 127.755 €. However economic analysis of this measure was not made because it was not possible to obtain the budget of the CRO system on time. Other two measures were analyzed in this work, and they involve savings in natural gas consumed in the boiler. The first one was the alteration of the temperature of domestic hot water from 87 °C to 70 °C. This measure does not imply any investment and generates 3,143 € annual savings. In the second one it was studied the viability of the implementation of a cross flow heat exchanger for domestic water heating to 70 °C, using the residual heat from exhaust gases of glass fusion. In this situation, the equipment budget varied between 3,500 € and 15,000 €. With a saving of 11,093 € year, the payback period range was between 0.32 and 1.4 years, revealing the heat exchanger implementation is viable for all situations suggested.
This report refers to the work developed in the company BA Vidro – Unidade de Avintes, in the frame of the course “Dissertação/Estágio” for the obtention of Master Degree in Chemical Engineering – Energy optimization in the Chemical Industry. The main goal was the design of an organic Rankine cycle (ORC) in order to produce electricity, using the residual heat from exhaust gases of a glass furnace. The exhaust gases are at 433.3°C and 296.5 °C, before and after they pass by the electrostatic filter. Among the considered fluids, toluene showed the highest electrical energy production, around 605 kW with the heat source at 296.5°C and 768.9 kW with the heat source at 433.3°C. Using this fluid, and for the same power output, the termal efficiencies obtained were 24,7 %, and 29,3 %, for an ORC with and without recuperator, respectively. The production of electricity is 48 % of the total consumption of the furnace, allowing an average annual savings of 127.755 €. However economic analysis of this measure was not made because it was not possible to obtain the budget of the CRO system on time. Other two measures were analyzed in this work, and they involve savings in natural gas consumed in the boiler. The first one was the alteration of the temperature of domestic hot water from 87 °C to 70 °C. This measure does not imply any investment and generates 3,143 € annual savings. In the second one it was studied the viability of the implementation of a cross flow heat exchanger for domestic water heating to 70 °C, using the residual heat from exhaust gases of glass fusion. In this situation, the equipment budget varied between 3,500 € and 15,000 €. With a saving of 11,093 € year, the payback period range was between 0.32 and 1.4 years, revealing the heat exchanger implementation is viable for all situations suggested.
Description
Keywords
Energia elétrica Otimização energética Ciclo de Rankine orgânico Gases de exaustão Eletrical energy Energy optimization Organic Rankine cycle Exhaust gases