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Abstract(s)
O presente trabalho teve como objetivo principal determinar a eficiência energética das três caldeiras quatubulares que fazem parte da central de Cogeração da RAR Açúcar e produzem vapor sobreaquecido. Estas utilizam como combustível o fuelóleo nº4 e/ou gás natural (GN), sendo que as caldeiras 1 e 3 têm a possibilidade de queimar os dois combustíveis, simultaneamente ou não, enquanto a caldeira 2 apenas queima fuelóleo nº4. Foram realizados ensaios em carga das 3 caldeiras e, após análise dos gases de combustão e das perdas energéticas, determinaram-se os rendimentos segundo as normas ASME
(American Society of Mechanical Engineers) PTC 4-2013, ADENE (2019) e o método direto. Concluiu-se que os métodos indiretos são mais rigorosos que o método direto, que apresentou limitações. Verificou-se também que o rendimento difere conforme o tipo de combustível queimado e no caso da queima de fuelóleo nº4, para um caudal médio de 536,2 kg/h, os valores de rendimento foram iguais a 71,4, 85,2 e 80,3% (ASME), para as
caldeiras 1, 2 e 3, respetivamente. Para o GN obteve-se um rendimento médio de 94,0% (ASME) na caldeira 1 e para a queima mista com razões de Fuelóleo nº4/GN de 90/10, 80/20 e 70/30, os rendimentos foram 83,2%, 84,6% e 83,2% (ASME), respetivamente. As perdas económicas associadas às perdas térmicas nas caldeiras foram significativas e com valores compreendidos entre [883,14 – 1223,67] €/dia. Num ensaio teste onde se
diminuiu o caudal de ar alimentado à caldeira 2, modificando a abertura da válvula de ar de 22% para 18%, as perdas diminuiram para um intervalo compreendido em [746,89 – 1087,65] €/dia, fazendo sentido implementar um sistema de controlo que otimize o processo de queima do combustível.
The main objective of this study was to determine the energy efficiency of the three watertube boilers from RAR Açúcar cogeneration plant. These use fuel oil No. 4 and/or natural gas (NG) as fuel, with boilers 1 and 3 having the option of burning both fuels simultaneously or not, while boiler 2 only burns fuel oil No. 4. On-load tests were carried out on the three boilers and, after analyzing the flue gases and measuring the energy losses, the yields were determined according to the ASME (American Society of Mechanical Engineers) PTC 4-2013 standards and the ADENE Manual (2019) for Energy Audits in Industry and the direct method. It was concluded that indirect methods are more accurate than the direct method, which has its limitations. It was also found that the efficiency differs according to the type of fuel burned and in the case of burning fuel oil no. 4, for an average flow rate of 536.2 kg/h, the efficiency values were equal to 71.4, 85.2 and 80.3%, for boilers 1, 2 and 3, respectively. With the same standard and for NG, an average yield of 94.0% was obtained for boiler 1 and for mixed firing with fuel oil/NG ratios of 90/10, 80/20 and 70/30, the yields were 83.2%, 84.6% and 83.2%, respectively. The economic losses associated with the boilers were significant and ranged from [883.14 - 1223.67] €/day. In a test run where the air flow fed to boiler 2 was reduced from a percentage of air valve opening of 22% to 18%, the losses fell to a range of [746.89 - 1087.65] €/day, so it made sense to implement a control system to optimize the fuel burning process.
The main objective of this study was to determine the energy efficiency of the three watertube boilers from RAR Açúcar cogeneration plant. These use fuel oil No. 4 and/or natural gas (NG) as fuel, with boilers 1 and 3 having the option of burning both fuels simultaneously or not, while boiler 2 only burns fuel oil No. 4. On-load tests were carried out on the three boilers and, after analyzing the flue gases and measuring the energy losses, the yields were determined according to the ASME (American Society of Mechanical Engineers) PTC 4-2013 standards and the ADENE Manual (2019) for Energy Audits in Industry and the direct method. It was concluded that indirect methods are more accurate than the direct method, which has its limitations. It was also found that the efficiency differs according to the type of fuel burned and in the case of burning fuel oil no. 4, for an average flow rate of 536.2 kg/h, the efficiency values were equal to 71.4, 85.2 and 80.3%, for boilers 1, 2 and 3, respectively. With the same standard and for NG, an average yield of 94.0% was obtained for boiler 1 and for mixed firing with fuel oil/NG ratios of 90/10, 80/20 and 70/30, the yields were 83.2%, 84.6% and 83.2%, respectively. The economic losses associated with the boilers were significant and ranged from [883.14 - 1223.67] €/day. In a test run where the air flow fed to boiler 2 was reduced from a percentage of air valve opening of 22% to 18%, the losses fell to a range of [746.89 - 1087.65] €/day, so it made sense to implement a control system to optimize the fuel burning process.
Description
Keywords
Caldeira Aquatubular Eficiência Energética Rendimento Fuelóleo Gás Natural ASME ADENE Boiler Watertube Energy efficiency Yeld Fuel oil Natural gas