Name: ALEXSANDER LUIZ QUINTÃO
Publication date: 30/08/2024
Examining board:
Name |
Role |
|---|---|
| JOÃO LUIZ MARCON DONATELLI | Examinador Interno |
| JOSE JOAQUIM CONCEICAO SOARES SANTOS | Presidente |
| JULIO AUGUSTO MENDES DA SILVA | Examinador Externo |
| PEDRO ROSSETO DE FARIA | Coorientador |
Summary: Energy efficiency plays a crucial role in transitioning to more sustainable energy sources and in the decarbonization of industries. In this context, the recovery of residual energy from processes stands out as a strategy, as exemplified by the carbo-chemical plant, which is the focus of this study. In this plant, calcination furnaces release exhaust gases that contain thermal and chemical energy. These gases, originating from six furnaces, have a total flow rate of 1.36 kg/s at 800°C, with a composition of 26% H, 4.2% CH, and 5% CO, among other gases, resulting in a total energy potential of 8.306 MW, with 1.632 MW being thermal energy and 6.674 MW being chemical energy. This study aims to analyze cogeneration system configurations based on steam cycles for energy recovery, focusing on heating the process's thermal oil as well as generating electricity. To achieve this, four configurations were simulated, starting from an example in Norway, using the IPSEpro software. These configurations were then evaluated based on the first and second laws of thermodynamics to assess their performance and identify opportunities for future optimization. The results indicated that, in addition to providing useful heat of 70 kW for heating the oil, it is possible to generate up to 2.654 MW of electrical power. The energy and exergy efficiencies of the steam cycles reach up to 43.35% and 80.45%, respectively, while the overall system achieves up to 32.8% and 32.09% in energy and exergy efficiencies, respectively. The exergy analysis revealed opportunities to improve various processes, with the highest exergy destructions occurring in the combustion chambers and boilers, as well as in the recoverable heat from the boiler exhaust gases. Although environmental assessment was not the primary objective of the study, it was qualitatively observed that there is a drastic reduction in the temperature of gases currently released into the atmosphere, as well as the combustion of combustible elements, particularly methane, which significantly reduces thermal and chemical pollution. Additionally, quantitatively, by generating electricity and thus reducing the demand on the electrical grid, more than 3,234 tons/year of CO emissions can be avoided. These indicators, along with the thermodynamic evaluation of the four simulated configurations, demonstrate the substantial theoretical potential for recovering this residual heat, offering significant benefits both in terms of efficiency and environmental impact reduction. This potential also suggests the need for further studies, particularly on economic feasibility, especially if the project is to be integrated into a carbon market.
