Sugarcane is a major crop in many countries. It is the most abundant lignocellulosic material in tropical countries such as South Africa. It is one of the plants with the highest bioconversion efficiency. The sugarcane crop is able to efficiently fix solar energy, yielding some 55 tons of dry matter per hectare of land annually. After harvest, the crop produces sugar juice and bagasse. Sugarcane bagasse is a residue that results from the crushing of sugarcane in the sugar industry. It is a renewable feedstock that can be used for power generation and manufacturing cellulosic ethanol. As biomass, sugarcane bagasse holds promise as a fuel source since it can produce more than enough electricity and heat energy to supply the needs of a common sugar factory. However, in the sugarcane industry the bagasse is currently burnt inefficiently in boilers that provide the heating for the industry. This project seeks to investigate the possibility of gasifying sugarcane bagasse as an efficient conversion technology. The investigation is necessary because fuel properties govern the gasifier design and ultimately, the gasification efficiency. Proximate and ultimate analysis of sugarcane bagasse was conducted after which the results were used to conduct a computer simulation of the mass and energy balance during gasification. The kinetic investigation undertaken through the TGA and DTG analyses revealed the activation energy and pre – exponential factor which were obtained by the model – free Kissinger method of kinetic analysis and were found to be 181.51 kJ/mol and 3.1 × 103/min respectively. The heating value of sugarcane bagasse was also measured and found to be 17.8 MJ/kg, which was used in the calculation of the conversion efficiency of the gasification process. Fuel properties, including moisture content and gasifier operating parameters were varied in order to determine optimum gasifier operating conditions that results in maximum conversion efficiency. The highest conversion efficiency was achieved at low moisture content after computer simulation of the gasification process. Moisture content also affected the volume of CO and H2 as the former decreases with increasing moisture content while the latter increases with increasing moisture content, accelerating the water – gas reaction. Scanning electron microscope fitted to an Energy dispersive X – ray spectroscopy was also used in order to view the shape and size distribution as well as determine the elemental composition of sugarcane bagasse. The results obtained established that the fuel properties and gasification conditions affect the conversion efficiency. During computer simulation, it was established that smaller particle size resulted in higher conversion efficiency. The smaller throat diameter also resulted in higher conversion efficiency. The throat angle of 25° also resulted in higher conversion efficiency. The temperature of input air was also found to be one of the major determining factors in terms of conversion efficiency. The dissertation presents the proximate and ultimate analysis results as well as the kinetic analysis results. The SEM/EDX analysis as well as the computer simulation results of the gasification process is also presented. The major contribution of this project was on the investigation of the gasification characteristics of sugarcane bagasse and the utilization of these in the design of a laboratory scale sugarcane bagasse gasifier with enhanced conversion efficiency through computer simulation.

As propriedades de pellets de biomassa utilizados como combustíveis são essenciais para o desempenho em processos termoquímicos, tais como combustão, gaseificação e pirólise. Estas propriedades podem afetar aspectos relacionados ao transporte, estocagem, manuseio, conversão de energia, emissões de gases no meio ambiente, bem como variáveis a serem controladas durante o processo de pelletização, influenciando diretamente o consumo de energia e os custos para a sua produção. Este trabalho apresenta um estudo realizado em uma indústria brasileira de produção de pellets de bagaço de cana-de-açúcar para determinação das principais propriedades do produto final e das variáveis do processo de produção. O objetivo deste trabalho é caracterizar, dentro do processo de pelletização, as principais propriedades físicas, químicas e mecânicas da matéria prima e do produto final, bem como conhecer os fluxos de massa, o consumo de energia e os custos envolvidos em cada etapa do processo. Como primeira parte dos resultados, concluiu-se que as propriedades de pellets de bagaço de cana-de-açúcar analisadas, tais como diâmetro, comprimento, umidade, densidade, durabilidade, quantidade de finos, poder calorífico, elementos químicos e teor de cinzas, não estão em total conformidade com outros trabalhos científicos realizados e com normas internacionais de comercialização e de qualidade de pellets de biomassa. Em segundo lugar, pôde-se conhecer a taxa de consumo de matéria prima e de produção de pellets, o consumo de energia e os custos envolvidos em cada etapa do processo de produção como secagem, moagem e pelletização. Por fim, foi encontrada uma função matemática em que o consumo de energia e os custos de produção crescem de maneira exponencial com a variação de umidade da matéria prima. / Properties of pellets used as biomass fuels are essential to the performance of thermochemical processes, such as combustion, gasification and pyrolysis. These properties can affect aspects related to transportation, storage, handling, power conversion, emissions into the environment as well as variables to be controlled during the pelletizing process, directly influencing the energy consumption and production cost. This paper presents a study in a Brazilian industry of sugarcane bagasse pellets in order to determine the main properties of pellets and process variables. The objective of this work is to characterize within the pelletizing process the main physical, chemical and mechanical properties on the raw material and final product, as well as knowing the mass flows, energy consumption and cost involved in each step of the process and its variations. As the first part of the results, it was conclude that the properties of the sugarcane bagasse pellets analyzed as diameter, length, moisture, density, durability, amount of fine, calorific value, chemical elements and ash content are not full compliance with other scientific work and international marketing standards and quality pellets biomass. Secondly, one can know the rate of material consumption and production of pellets, energy consumption and costs for each step of the production process as drying, grinding and pelletizing. Finally, a mathematical function in which the power consumption and production costs grow exponentially with the variation of moisture of the raw material entry was found.

As propriedades de pellets de biomassa utilizados como combustíveis são essenciais para o desempenho em processos termoquímicos, tais como combustão, gaseificação e pirólise. Estas propriedades podem afetar aspectos relacionados ao transporte, estocagem, manuseio, conversão de energia, emissões de gases no meio ambiente, bem como variáveis a serem controladas durante o processo de pelletização, influenciando diretamente o consumo de energia e os custos para a sua produção. Este trabalho apresenta um estudo realizado em uma indústria brasileira de produção de pellets de bagaço de cana-de-açúcar para determinação das principais propriedades do produto final e das variáveis do processo de produção. O objetivo deste trabalho é caracterizar, dentro do processo de pelletização, as principais propriedades físicas, químicas e mecânicas da matéria prima e do produto final, bem como conhecer os fluxos de massa, o consumo de energia e os custos envolvidos em cada etapa do processo. Como primeira parte dos resultados, concluiu-se que as propriedades de pellets de bagaço de cana-de-açúcar analisadas, tais como diâmetro, comprimento, umidade, densidade, durabilidade, quantidade de finos, poder calorífico, elementos químicos e teor de cinzas, não estão em total conformidade com outros trabalhos científicos realizados e com normas internacionais de comercialização e de qualidade de pellets de biomassa. Em segundo lugar, pôde-se conhecer a taxa de consumo de matéria prima e de produção de pellets, o consumo de energia e os custos envolvidos em cada etapa do processo de produção como secagem, moagem e pelletização. Por fim, foi encontrada uma função matemática em que o consumo de energia e os custos de produção crescem de maneira exponencial com a variação de umidade da matéria prima. / Properties of pellets used as biomass fuels are essential to the performance of thermochemical processes, such as combustion, gasification and pyrolysis. These properties can affect aspects related to transportation, storage, handling, power conversion, emissions into the environment as well as variables to be controlled during the pelletizing process, directly influencing the energy consumption and production cost. This paper presents a study in a Brazilian industry of sugarcane bagasse pellets in order to determine the main properties of pellets and process variables. The objective of this work is to characterize within the pelletizing process the main physical, chemical and mechanical properties on the raw material and final product, as well as knowing the mass flows, energy consumption and cost involved in each step of the process and its variations. As the first part of the results, it was conclude that the properties of the sugarcane bagasse pellets analyzed as diameter, length, moisture, density, durability, amount of fine, calorific value, chemical elements and ash content are not full compliance with other scientific work and international marketing standards and quality pellets biomass. Secondly, one can know the rate of material consumption and production of pellets, energy consumption and costs for each step of the production process as drying, grinding and pelletizing. Finally, a mathematical function in which the power consumption and production costs grow exponentially with the variation of moisture of the raw material entry was found.