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Abstract: The rational use of energy became a priority for all industries in Brazil after the energetic rationing in 2001. The aim of this work is to assess a proposal of a power generation system for Companhia Siderúrgica Tubarão, a steel mill plant. The current system is based on a regenerative Rankine cycle using two gases from steel production—blast furnace gas (BFG) and coke oven gas (COG)—to generate electric power and occasionally steam for the process. The proposed system is a combined cycle comprising two gas turbines, two heat recovery steam generators (HRSGs), and a steam turbine. The fuel for the gas turbines is BFG, and the supplementary firing of HRSG uses COG. The proposed HRSGs work at three pressure levels. The system was assessed by means of two thermoeconomic methodologies, Theory of Exergetic Cost and Thermoeconomic Functional Analysis; exergetic and monetary costs of power production were calculated and compared to the respective values of the current system. [Copyright &y& Elsevier]

The process of intermittent drying in prolate spheroidal bodies was simulated assuming liquid diffusion to be the sole mass transport process, a constant diffusion coefficient and equilibrium conditions at the surface. The mass diffusion equation in a prolate spheroidal coordinate system was used for a two-dimensional case. Due to the use of a dimensionless coordinate system, a Fourier number for tempering is defined, in order to determine the dimensionless time required to achieve a flat moisture content profile. Assuming that the drying process is stopped only once at a fixed point, the tempering Fourier number was determined for aspect ratios of 1.1, 2.0 and 5.0. Many cases were studied, changing the tempering Fourier and aspect ratio of the body. Focusing on the drying rate, the effect of one, two and four drying passes was studied for different interruption points in the process and aspect ratios of 1.1, 2.0 and 5.0, in all cases using the continuous process as a comparison. From the numerical results it was found that during the tempering process, the drying rate and the final mean moisture content are affected by the tempering Fourier number, multipass drying and geometrical dimensions of the body. [ABSTRACT FROM AUTHOR]

Sugarcane is one of the most important industries of the Brazilian economy, and its main products are sugar and ethanol. Most of the industrial plants produce both products in an integrated process, in which the sugarcane bagasse is a by-product that can be used as a fuel in the cogeneration system. The bagasse is used as the only fuel of the plant, supplying all energy required for the process, and also producing electricity surplus that may be sold to the grid. In this paper, exergy analysis is used to assess an integrated sugar and ethanol plant with its cogeneration system. The plant was divided into eight sub-systems to evaluate the irreversibility generation in each separately. Data from typical sugarcane factories in Brazil, which produce sugar and ethanol, were used in the process simulation. The analysis has shown that the sub-systems with the highest contribution for the total irreversibility generation of the plant were co-generation, juice extraction and fermentation. Some improvements are proposed, including process thermal integration and the introduction of more efficient equipments for prime mover and steam and electricity generation. The analysis indicated that the total irreversibility could be reduced by 10% should those changes be implemented. [Copyright &y& Elsevier]

This work presents a two-dimensional diffusional model to predict the simultaneous mass transfer and shrinkage during drying of solids with prolate spheroidal shape, considering that the changes in volume of solid are equal to the volume of evaporated water. The resulting equations are numerically solved, using the finite-volume method. This model was used to study numerically the effect of the air-drying conditions and shrinkage on the drying kinetic of banana peel for six experiments, considering the natural shape of this fruit. Here, it was treated as an ellipsoid of revolution. Several results are shown and analyzed such as the comparison between numerical and experimental data; the dimensionless shrinkage parameters; the relationships of length, superficial area and volume; the moisture content distribution and finally the mass transfer and diffusion coefficients. [Copyright &y& Elsevier]

The Brazilian Energy Matrix is characterised by the presence of Renewables, whose participation reached 46.1% in 2019, equivalent to 133.8 Mtoe, of which 18.0% represented the sugarcane biomass share, 12.4% the hydraulic, 8.7% the wood and charcoal, and 7.0% corresponded to other renewables. The sugarcane industry produces sugar, ethanol, and electricity as main products and, considering the total primary energy produced, 52.861 Mtoe comes from sugarcane products (BEN, 2020). Another aspect of this industry is that it is energy self-sufficient, that being so, the energy used in the production process is also produced (from bagasse) in the same process. The aforementioned data show the significance of the sugarcane industry for the country and being this an energy industry, there is no doubt that the energy management holds importance to its industrial process. The present work will address different alternatives to improve the industrial process of sugarcane, aiming at optimising the energy management. Among the proposals to be presented, the following can be mentioned: increasing of electric energy in cogeneration, thermal integration of process streams using the Pinch Point method, second-generation ethanol production, water use in the process, integration with biodiesel production, vinasse disposition aiming at increasing energy production and reducing pollution. The main objective is to identify each proposal's influence on and contribution to the improvement of the performance and efficiency in the production process from sugarcane. • Renewables participates with 46,1 %, in the Brazilian Energy Matrix. • 18% is the sugarcane biomass share in the renewables in the Brazilian Energy Matrix. • The sugar cane industry produces simultaneously sugar, ethanol, and electricity. • The fuel used in the production process is also produced in it. • Different alternatives to improve the process of sugarcane industry were analysed. [ABSTRACT FROM AUTHOR]

Abstract: Vyazovkin''s model-free kinetic algorithms were applied to determine conversion, isoconversion and apparent activation energy to both dehydration and combustion of sugarcane bagasse. Three different steps were detected with apparent activation energies of 76.1±1.7, 333.3±15.0 and 220.1±4.0kJ/mol in the conversion range of 2–5%, 15–60% and 70–90%, respectively. The first step is associated with the endothermic process of drying and release of water. The others correspond to the combustion (and carbonization) of organic matter (mainly cellulose, hemicellulose and lignin) and the combustion of the products of pyrolysis. [Copyright &y& Elsevier]