Gasification of biomass is a one of the several technologies for energy production from biomass. Biomass is a promising renewable source of energy and is in a centre of attention of energy industry not only in the Czech Republic, but also in the EU and in the world. Gasification is a thermo chemical transformation of fuel with access of understoicheiometric amount of oxidizer which produces gas of low heating value. Its main combustible components are hydrogen, carbon dioxide and methane. Produced gas may be further used in power and heating plants. Besides combustible and neutral components, gas also contains pollutants such as sulphur compounds, chlorine compounds, ash and tar. It is tar which is considered to be the underbelly of gasification as it causes, along with ash, fouling in transport tracks and terminal equipment, and blocks direct application of gas. This dissertation thesis presents design of filter for elimination of tar from the gas generated in fluid gasification equipment. This work is closely related to current research at Energy Institute at Faculty of Mechanical Engineering at Brno University of Technology. First part deals with theoretical background of this issue. Biomass properties are mentioned in relation to gasification. Types of gasification equipment are described and principle of gasification including chemical reactions is given in detail. Special part is dedicated to pollutants in the gas, especially to production of tar and its properties, which is important for consequent work. Main focus is on possibilities of catalytic cleaning of gas from tar. Principle of tar decomposition is described and types and properties of catalysts are given. Part of the thesis tackles the issue of real operations and loss of efficiency of catalyst due to sulphur compounds, sintering and carbon fouling. Based on experience and analysis in the first part of the thesis, concept of elimination of tar from gas was laid out. In addition to that, method for measurement at Biofluid 100 experimental unit was outlined and filter for testing of industrial catalysts using metal was designed. Series of experiments were further conducted in order to find out efficiency of three opted catalysts for tar decomposition. Results of these experiments are described in detail and assessed in the conclusion of this thesis which also contains outline for economic assessment of method of gas cleaning using catalysts.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第20097号 / エネ博第344号 / 新制||エネ||69(附属図書館) / 33213 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 坂 志朗, 教授 髙野 俊幸, 准教授 河本 晴雄 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

A cold flow model circulating fluidized bed reactor was designed and built to determine any correlation that may exist between the percentage of fine bed material in the overall reactor inventory, and both the solids circulation rate as well as the riser axial particle distribution. It was determined that for Geldart group B particles (sand), there may be a direct relationship between an increase in the percentage of fine particles and an increase in the solids circulation rate for a given riser superficial velocity. There may also be a direct relationship between the percentage of fine particles and an increase in the overall solids concentration in the upper zones of the riser for a given riser superficial velocity. It is theorized that these effects are due to a reduction in the overall mean particle size of any particle clusters formed due to the increase of the percentage of fines.

In this work it is presented an equilibrium model, capable to predict the composition of the generated gas, its Lower Heating Value (LHV), the gasification efficiency, the ratio air/biomass and the  ratio gas/biomass in a downdraft gasifier. The model describes the influence of  the moisture content of the biomass and the gasification temperatures on the composition and properties of the produced gases, like the low heating value (LHV). It is assumed that all the chemical reactions taking place  in the gasification area are in thermodynamic equilibrium. The model doesn't considered tar formation. It is not considered formation of other hydrocarbons (CxHy) than methane. The types of biomass used for modelling are: sugarcane bagasse, paddy husk, pine sawdust, mixed paper waste and municipal solid waste. The effect of gasification temperature and moisture content of biomass over the gas composition has been also investigated. Also an exergo-economic analysis of cogeneration system forming by a downdraft gasifier associated to an internal combustion engine was carried out, using sugar cane bagasse, rice husk, and pine sawdust, as fuel in gasification processes. At 700°C the highest amount of CO and CH4 are produce. The amount of CH4 and CO decrease with the temperature when the gasification temperature is increased from 700°C to 1000°C. The amount produced H2 does change so much between the gasification at 700°C and 1000°C. But the amount produced hydrogen is somewhat higher at 800°C. The lower heating value (LHV) of the synthesis gas from gasification of sugarcane bagasse the LHV of the produced gas is 4,09MJ/Nm3; for gasification of pine the LHV of the produced gas is 5,32MJ/Nm3; for gasification of rice husk the LHV of the produced gas is 3,14MJ/Nm3, for gasification of mixed paper waste the LHV of the produced gas is 4,51%, and for gasification of municipal solid  waste the LHV of the produced gas is 3,95MJ/Nm3. The cold and hot efficiency of gasification process at 800°C for bagasse with 20% moisture content are  55,32% and 84,90% respectively.

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Clean and efficient electricity can be generated using an Integrated Gasification Combined Cycle (IGCC). Although IGCC is typically used with coal, it can also be used to gasify other carbonaceous species like biomass and petroleum coke. It is important to understand the pyrolysis and gasification of these species in order to design commercial gasifiers and also to determine optimal conditions for operation. High heating-rate (100,000 K/s) pyrolysis experiments were performed with biomass (sawdust) in BYU's atmospheric flat-flame burner reactor at conditions ranging from 1163 to 1433 K with particle residence times ranging from 23 to 102 ms. Volatile yields and mass release of the sawdust were measured. The measured pyrolysis yields of sawdust are believed to be similar to those that would occur in an industrial entrained-flow gasifier since biomass pyrolysis yields depend heavily on heating rate and temperature. Sawdust pyrolysis was modeled using the Chemical Percolation Devolatilization model assuming that biomass pyrolysis occurs as a weighted average of its individual components (cellulose, hemicellulose, and lignin). Thermal cracking of tar into light gas was included using a first-order kinetic model. The pyrolysis and CO2 gasification of petroleum coke was studied in a pressurized flat-flame burner up to 15 atm for conditions where the peak temperature ranged from 1402 to 2139 K. The measured CO2 gasification kinetics are believed to be representative of those from an entrained-flow gasifier since they were measured in similar conditions of elevated pressure and high heating rates (100,000 K/s). This is in contrast to the gasification experiments commonly seen in the literature that have been carried out at atmospheric pressure and slow particle heating rates. The apparent first-order Arrhenius kinetic parameters for the CO2 gasification of petroleum coke were determined. From the experiments in this work, the ASTM volatiles value of petroleum coke appeared to be a good approximation of the mass release experienced during pyrolysis in all experiments performed from 1 to 15 atm. The reactivity of pet coke by CO2 gasification exhibited strong pressure dependence.

The growing amount of landfill waste within the EU could pose a problem in the future should there not be any effective treatment methods. This study aims to investigate the performance of landfill waste in a plasma gasification process by simulating the process in ASPEN Plus. The investigation is focused on the energy recovery potential of RDF based on composition and heating value of syngas, and cold gas efficiency (CGE). The plasma gasification system consists of a shaft gasifier and a separate tar cracking reactor where high temperature plasma is used for conversion of tar compounds considered in the model, which are toluene and naphthalene. In addition, the model is divided into five sections, namely drying, pyrolysis, char gasification, melting and tar cracking. Mass and energy balance of the system was performed to better understand the system. The results show that the plasma gasification system was able to produce a syngas with a LHV of 4.66 MJ/Nm3 while improving syngas yield by attaining a higher content of hydrogen. Thus, the plasma tar cracking of tar compounds can achieve a clean syngas and improve syngas yield. Parameter study on effect of ER show that syngas has higher heating value and CGE at lower ER. On the other hand, preheated air can help recover energy from the system while lowering the ER required for the char gasification process to meet the heat demand from partial combustion. The findings implied that landfill waste has energy potential by using a suitable treatment process such as plasma gasification.

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Due to the advancement of global warming internationally, increasing emphasis is being placed on the environmental accountability of everyone from countries to processes. This study presents novel research on the environmental impacts and economic trade-offs for a processes co-producing electricity, methanol, dimethyl ether (DME) and Fischer Tropsch (FT) fuels from different feedstock ratios of biomass, natural gas, and nuclear hydrogen generated through a CuCl cycle are analyzed for operation in Canada to produce transportation fuels. This study also considers the use of carbon capture and sequestration (CCS), the location of the plant in either Ontario and Alberta, and the input ratio of the feedstocks. This combination of carbonless heat and a “carbon neutral” biomass feedstock would contribute to the net reduction of greenhouse gas (GHG) emissions. In Part I of this work, the model for this BGNTL process was developed. This work expands on the model and evaluates the economics and environmental impacts this plant would have in both Ontario and Alberta based on their local costs, resource availability, and current electricity grid contributions. The analysis investigates the effectiveness of the emission reduction of the products and processes when compared to their cost. It is shown that an increase in the ratio of biomass to natural gas in feedstock, the use of a solid oxide fuel cell (SOFC), and the production of additional electricity while reducing the emissions of the process, increases the cost of CO2e avoided. The results show that the BGNTL concept can be an economically attractive way of reducing net transportation sector GHG emissions in both Ontario and Alberta in meaningful quantities. Optimal cases for both biofuel and FT fuel production contain a single output fuel production process, produce fuels over electricity where possible, and use a gas turbine (GT) for the electricity production that occurs. / Thesis / Master of Engineering (MEngr) / This paper examines a system producing a combination of transportation fuels including diesel, gasoline, methanol (MeOH), dimethyl ether (DME) and electricity from biomass, natural gas and hydrogen. The design of the system units used in the process was done in a previous study, this work expands on the design looking specifically at locating the plant in Ontario and Alberta for their raw resources, electricity grids, and current production methods of fuel. Variations of the plant are compared to each other and current fuel and electricity production with an aim of reducing the cost and emissions created while producing and using the fuels. It is found that increasing the amount of biomass used significantly reduces the emissions but does not create a competitive process due to how expensive it is. Results show that this type of system can decrease transportation sector emissions with a similar additional cost as other current alternatives.

To examine the effects of operational parameters on syn-gas quality and biouel conversion rate under various running conditions, an experimental study of hardwood chip?s gasification in a downdraft gasifier was conducted. The resulting syn-gas had average low heating value of 5.79 ± 0.52 MJ/ Nm3, tar concentration of 14.06 ± 8.54 mg/Nm³, particulate concentration of 3.05 ± 1.79 mg/Nm³, hardwood conversion rate of 2.37±0.24 Nm³/kg, and carbon conversion rate of 98.01 ± 0.53%. This syn-gas is of acceptable quality to be used as a fuel source for internal combustion engine operations. The gasifier?s grate temperature had no evident effects on syn-gas quality and conversion rate within a range of 740 to 817oC. The particulate contents in preiltered syn-gas significantly increased when the gas flow rate changed from 36 to 56 Nm3/h. When the moisture content of hardwood chips increased, tar content of postiltered syn-gas significantly increased, and CO content significantly decreased.