Taisa Shimosakai de Lira

Air quality prediction in Uberlândia, Brazil, using linear models and neural networks

Abstract Particulate air pollution is associated with a range of effects on human health, including effects on the respiratory and cardiovascular systems, asthma and mortality. Hence, the development of an efficient forecasting and early warning system for providing air quality information towards the citizen becomes an obvious and imperative need. The objective of this work was to investigate that forecasting capability using linear models (such as ARX, ARMAX, output-error and Box-Jenkins), and neural networks. They were used meteorological variables and 24-h PM 10 concentration of the present day as input data. As output foreseen by the models, the 24-h PM 10 concentration is obtained, with horizon of prediction of up to three days ahead. The results showed that fairly good estimates can be achieved by all of the models, but Box-Jenkins model showed best fit and predictability.

Determination of activation energy of pyrolysis of carton packaging wastes and its pure components using thermogravimetry

Many processes have been used for recycling of carton packaging wastes. The pyrolysis highlights as a promising technology to be used for recovering the aluminum from polyethylene and generating products with high heating value. In this paper, a study on pyrolysis reactions of carton packaging wastes and its pure components was performed in order to estimate the kinetic parameters of these reactions. For this, dynamic thermogravimetric analyses were carried out and two different kinds of kinetic models were used: the isoconversional and Independent Parallel Reactions. Isoconversional models allowed to calculate the overall activation energy of the pyrolysis reaction, in according to their conversions. The IPR model, in turn, allowed the calculation of kinetic parameters of each one of the carton packaging and paperboard subcomponents. The carton packaging pyrolysis follows three separated stages of devolatilization. The first step is moisture loss. The second stage is perfectly correlated to devolatilization of cardboard. The third step is correlated to devolatilization of polyethylene.

Modelling of fertilizer drying in a rotary dryer: parametric sensitivity analysis

This study analyzed the influence of the following parameters: overall volumetric heat transfer coefficient, coefficient of heat loss, drying rate, specific heat of the solid and specific heat of dry air on the prediction of a model for the fertilizer drying in rotary dryers. The method of parametric sensitivity using an experimental design was employed in this study. All parameters studied significantly affected the responses of the drying model. In general, the model showed greater sensitivity to the parameters drying rate and overall volumetric heat transfer coefficient.

Pyrolysis of Sugarcane bagasse: A consecutive reactions kinetic model from TGA experiments

The pyrolysis kinetics of sugarcane bagasse in nitrogen flow was studied by thermogravimetric analysis from room temperature to 1173 K at different heating rates (1.5, 3, 5, 10, 15, 20, 30 and 50 K/min). As there are three distinct devolatilization peaks in the DTG curve, each peak was associated to thermal decomposition of an individual biomass subcomponent (hemicellulose, cellulose and lignin). The kinetic model adopted was a consecutive reactions model. The kinetic parameters of the pyrolysis process, such as activation energy and pre-exponential factor, were calculated by least squares non-linear method and Scilab are used as the simulation tool. The simulated results showed a good agreement with the experimental data and the parameters found are similar to reported by the literature.

Isoconversional Kinetic Analysis of Pyrolysis of Sugarcane Bagasse

This paper presents a kinetic study of pyrolysis of sugarcane bagasse from dynamic thermogravimetric experiments (TG). The methods of Kissinger, Ozawa, Starink, Kissinger-Akahira-Sunose and Friedman were used to estimate the activation energy. These methods consider the temperature shifts with increase of heating rate for a given conversion in dynamic TG tests. The activation energy values obtained by the isoconversional methods were in a range 182.8 192.4 kJ·mol-1, values very close to the other biomasses presented by literature.

Dynamic analysis of reaction kinetics of carton packaging pyrolysis

Abstract As reported in the literature, the post-consumption carton packaging has been recycled using different process. Pyrolysis can be a promising technology to be used for recovering the aluminum from polyethylene and generating products with high heating value. In this research paper, by using thermogravimetric analysis (TGA), a kinetic study on pyrolysis reactions was performed. Furthermore, the activation energy of pyrolysis reaction was estimated using the methodology proposed by Ozawa (1965).

Factor effect of operating conditions on the leaching of fly ashes from a pulp and paper mill

The non-process-elements (NPEs) in the pulp and paper production, in particular chloride (Cl-) and potassium (K+), eventually accumulate in a sodium sulfate recovery cycle of a paper plant, especially on boiler fly ashes (flue gas cleaning). This accumulation often leads to fouling and corrosion. Thus, in order to reduce such problems, a leaching unit is typically integrated aiming to remove Cl- and K+ and recover sodium sulfate (Na2SO4) from boiler fly ashes. In this context, this research is focused on investigating the effects of temperature, ash concentration and pH on the separation efficiency (Cl- and K+ removal and Na2SO4 recovery) of recovery boiler fly ashes using design of experiments in a devised laboratory setup. As expected from the literature, the results obtained reveals that concentration has the most significant effect on the response variables followed by temperature; whereas pH, not mentioned in this application so far, also has a significant effect. The optimum operating condition, which yields 84 wt% of Na2SO4 recovery and 97 wt% of Cl- and K+ removal, is achieved at 60 °C, 50 wt% of ash and pH 9.0. For practical applications, this optimal condition reduces the accumulation of NPEs and mitigates the risks of fouling and corrosion.