Approximation to distributed activation energy model for residual logging of cedrus deodora using weibull distribution

The paper focuses to explain the influence of some relevant parameters of biomass pyrolysis on the numerical solution of isothermal n th order distributed activation energy model (DAEM). The upper limit of “dE”, the frequency factors, the reaction order, the shape and location parameters of the Weibull distribution are studied. These parameters have been used for estimating the kinetic parameters of the isothermal Weibull DAEM from thermo analytical data of loose biomass. Moreover, asymptotic approach has been adopted to find the solution of DAEM.Authors wish to acknowledge the support of Department of Mathematics, Statistics and Computer Science of Govind Ballabh Pant University of Agriculture and Technology (GBPUA&T) for assisting in their work. They also express their sincere gratitude to IIC, IIT Roorkee and SAIF, IIT Bombay for their help in conducting the experiments on Cedrus Deodara leaves.Publisher's Versio

Numerical Solution of nth Order DAEM for Kinetic Study of Lignocellulosic Biomass Pyrolysis

The aim of the present study was to explore the most optimal configuration to numerically solve Distributed Activation Energy Models (DAEMs). DAEMs are useful in obtaining the kinetic parameters in non-isothermal kinetic studies using a thermogravimetry analyzer (TGA). Compared to other kinetic models, DAEMs provide an additional kinetic parameter that quantifies the extent of the reaction (σ) for each reaction’s mean activation energy (E ̅). Although DAEMs are efficacious in kinetic studies, solving DAEMs numerically is challenging. The DAEM equation includes double integration with respect to activation energy and temperature, which involves various numerical discretizations. Previously, many researchers utilized a DAEM to explicate complex reactions such as lignocellulosic biomass pyrolysis. However, most of them have yet to propose a numerical approach to solve DAEMs. Therefore, by exploring multiple numerical calculation configurations, here we present a general structure to numerically solve nth order and first-order DAEMs. The exploration includes determining the optimal integration limit of activation energy and the discretization of activation energy and temperature integration. From the investigation, we came up with a configuration that limits the integration of activation energy from E ̅-3σ to E ̅+3σ. Meanwhile, the number of integration points for temperature and activation energy must be 51 and 21, respectively. By using this configuration, DAEM can be utilized optimally in kinetic studies

Numerical Solution of nth Order DAEM for Kinetic Study of Lignocellulosic Biomass Pyrolysis

The aim of the present study was to explore the most optimal configuration to numerically solve Distributed Activation Energy Models (DAEMs). DAEMs are useful in obtaining the kinetic parameters in non-isothermal kinetic studies using a thermogravimetry analyzer (TGA). Compared to other kinetic models, DAEMs provide an additional kinetic parameter that quantifies the extent of the reaction (σ) for each reaction’s mean activation energy (E ̅). Although DAEMs are efficacious in kinetic studies, solving DAEMs numerically is challenging. The DAEM equation includes double integration with respect to activation energy and temperature, which involves various numerical discretizations. Previously, many researchers utilized a DAEM to explicate complex reactions such as lignocellulosic biomass pyrolysis. However, most of them have yet to propose a numerical approach to solve DAEMs. Therefore, by exploring multiple numerical calculation configurations, here we present a general structure to numerically solve nth order and first-order DAEMs. The exploration includes determining the optimal integration limit of activation energy and the discretization of activation energy and temperature integration. From the investigation, we came up with a configuration that limits the integration of activation energy from E ̅-3σ to E ̅+3σ. Meanwhile, the number of integration points for temperature and activation energy must be 51 and 21, respectively. By using this configuration, DAEM can be utilized optimally in kinetic studies

Review of experimental methods to determine spontaneous combustion susceptibility of coal – Indian context

This paper presents a critical review of the different techniques developed to investigate the susceptibility of coal to spontaneous combustion and fire. These methods may be sub-classified into the two following areas: (1) Basic coal characterisation studies (chemical constituents) and their influence on spontaneous combustion susceptibility. (2) Test methods to assess the susceptibility of a coal sample to spontaneous combustion. This is followed by a critical literature review that summarises previous research with special emphasis given to Indian coals

Análise da decomposição térmica de palha de cana-de-açúcar em atmosferas inerte e oxidante mediante métodos termoanalíticos

Orientadores: Katia Tannous, Edgardo Olivares GomezTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuímicaResumo: Este trabalho teve por objetivo o estudo cinético da decomposição térmica da palha de cana-de-açúcar (Saccharum officinarum Linnaeus) em atmosferas inerte e oxidante. O diâmetro médio das partículas foi de 0,510 mm obtido entre as peneiras padrão Tyler de número 28 e 35. As características térmicas (base seca) foram obtidas conforme: materiais voláteis=86,6% (ASTM E872¿82), cinzas=3,8% (ASTM E1755¿01) e carbono fixo=9,6% por diferença; e poder calorífico superior de 18,6 MJ/kg obtido mediante bomba calorimétrica. A característica química foi determinada através de um analisador elementar obtendo-se os teores mássicos de carbono=42,8%, hidrogênio=6,2%, nitrogênio=0,3% e o oxigênio=46,9% por diferença em base seca e livre de cinzas. A determinação dos teores de hemicelulose=33% e celulose=40% foi feita mediante a técnica ANKOM A200 baseada no método de Van Soest. O teor de lignina=22% foi determinado aplicando o método de Klason baseado em hidrólise ácida. Os experimentos de decomposição térmica foram realizados em um analisador termogravimétrico (TG) e o fluxo de calor foi medido em um calorímetro diferencial de varredura (DSC), usando nitrogênio e ar sintético como meio reativo. Estas análises foram realizadas utilizando quatro taxas de aquecimento (1,25; 2,5; 5 e 10 °C/min) em nitrogênio e três (2,5; 5 e 10 °C/min) em ar sintético aplicando massas em torno de 3 mg. A análise cinética realizada para as duas atmosferas abrangeu três esquemas de reações: reação global, reações consecutivas, e reações paralelas. A modelagem cinética através do esquema de reação global foi realizada aplicando os métodos isoconversionais de Friedman (nitrogênio) e Vyazovkin (ar sintético). Em atmosfera inerte, obteve-se energia de ativação de 149,7 kJ/mol, fator pré-exponencial de 1,82 x 109 s-1 e modelo de reação de difusão bidimensional. No entanto, em atmosfera oxidante não foi possível modelar a reação através deste esquema de reação. Analisando reações globais de primeira ordem através de modelos de ajuste e considerando 805 cenários diferentes, obtiveram-se correlações entre fator pré-exponencial e energia de ativação, correlacionando a taxa de aquecimento, temperatura e taxa de conversão no pico. O esquema de três reações consecutivas descreveu muito bem os dados experimentais, aplicando reações de primeira ordem obtendo-se energias de ativação de 133, 198 e 56 kJ/mol, e 200, 300 e 100 kJ/mol em atmosfera inerte e oxidante, respectivamente. Os fatores pre-exponenciais de 2×109, 5×103, e 5 s-1 foram obtidos em atmosfera inerte e 2×1016, 3×1028, e 5×104 s-1 em oxidante. A aplicação do esquema de reações paralelas e independentes foi realizada avaliando três reações de primeira ordem em atmosfera inerte e seis em atmosfera oxidante. Os resultados experimentais e teóricos mostraram uma boa concordância, obtendo-se energias de ativação de 142, 212, e 40 kJ/mol em atmosfera inerte e 176, 313, 150, 80, 150, e 100 kJ/mol em oxidante. Os fatores pre-exponenciais obtidos foram em atmosfera inerte 1×1010, 8×1014, e 0,3 s-1, e em oxidante 1×1014, 1×1025, 2×1010, 5×103, 1×108, e 1×104 s-1. Finalmente, o calor de reação em atmosfera inerte foi endotérmico, requerendo energia máxima de 1 MJ/kg em 350 °C, e em atmosfera oxidante foi completamente exotérmico liberando até 8 MJ/kgAbstract: The aim of this work was the kinetic study of the thermal decomposition of sugarcane straw (Saccharum officinarum Linnaeus) in inert and oxidative atmospheres. The mean diameter of particles was 0.510 mm obtained between the Tyler standard sieves number 28 and 35. The thermal characteristics (dry base) were determined according to: volatile matter content = 86.6% (ASTM E872-82), ash content=3.8% (ASTM E1755-01) and fixed carbon content =9.6% by difference, and higher heating values of 18.6 MJ/kg obtained with a bomb calorimeter. The chemical characteristic were determined through an elemental analyzer, obtaining in dry and ash free basis carbon=42.8%-m, hydrogen=6.2%-m, nitrogen=0.3%-m and oxygen=46.9%-m by difference. The sample chemical composition was hemicellulose=33% and cellulose=40% determined by the application of the ANKOM A200 technique, based on the Van Soest's method. The lignin content=22% was obtained applying the Klason¿s method based on acid hydrolysis. The thermal decomposition experiments were carried out in a thermogravimetric analyzer (TG) and the heat flux was measured in a differential scanning calorimeter (DSC), using nitrogen and synthetic air atmospheres, respectively. These analyses were carried out using four heating rates (1.25, 2.5, 5, and 10 °C/min) in nitrogen, and three (2.5, 5, and 10 °C/min) in synthetic air applying sample mass around 3 mg. The kinetic analysis in both atmospheres covered three reaction schemes: global reaction, consecutive reactions, and parallel reactions. In the global reaction analysis were applied the isoconversional methods of Friedman (nitrogen) and Vyazovkin (synthetic air). In inert atmosphere, was obtained activation energy of 149.7 kJ/mol, pre-exponential factor of 1,82 x 109 s-1, and reaction model of bi-dimensional diffusion. However, in oxidative atmosphere, it was not possible to modeling the reaction through this reaction scheme. Analyzing first order global reactions through fitting models and considering 805 different scenarios, were obtained correlations between pre-exponential factor and activation energy, correlating the heating rate, peak temperature, and peak conversion rate. The three consecutive first order reactions scheme represented the experimental data obtaining activation energies of 133, 198, and 56 kJ/mol in inert atmosphere, and 200, 300, and 100 kJ/mol in oxidative atmosphere. The pre-exponential factors correspondent were 2×109, 5×103, and 5 s-1 in inert atmosphere and 2×1016, 3×1028, and 5×104 s-1 were oxidative atmosphere. The kinetic modeling through the independent parallel reactions scheme was carried out evaluating three and six first order reactions in inert and oxidative atmosphere, respectively. The experimental and theoretical results showed a good agreement obtaining activation energies of 142, 212, and 40 kJ/mol in inert atmosphere, and 176, 313, 150, 80, 150, and 100 kJ/mol in oxidative atmosphere. The pre-exponential factors were 1×1010, 8×1014, and 0,3 s-1 in inert atmosphere and 1×1014, 1×1025, 2×1010, 5×103, 1×108, and 1×104 s-1 in oxidative atmosphere. Finally, the heat of reaction in inert atmosphere was endothermic requiring maximum energy of 1 MJ/kg at 350ºC, and in oxidative atmosphere, it was completely exothermic releasing 8 MJ/kgDoutoradoDesenvolvimento de Processos QuímicosDoutor em Engenharia Química33003017034P8CAPE