The pyrolysis of biomass is a thermochemical process in which woody biomass is converted to several high-value products such as bio-oil, bio-char and syngas. The forestry sector has shown particular interest in this process as a large quantity of biomass is produced as an underutilised by-product in this sector annually. Dual fluidised beds (DFBs) have been identified as a feasible reactor system for this process. However, little attention has been given to the optimisation or to the design of a scalable DFB for the pyrolysis of biomass process. Therefore, the objective of the current project was the design, modelling and construction of a scalable dual fluidised bed system for the pyrolysis of biomass. In order to achieve this objective, several tasks were performed, which included the following: <ul> <li> A literature study was done in order to obtain a theoretical foundation for the current project.</li> <li> A novel dual fluidised bed reactor system was designed, which included the block flow diagram and the process and instrumentation diagram for the system.</li> <li> A cold unit of the system was built in order to test the performance of the system.</li> <li> A comprehensive model for the system was developed, which included mass and energy balance considerations, hydrodynamics and reaction kinetics.</li> <li> A complete pilot-scale system of the proposed design was built and tested at the University of Pretoria.</li></ul> Solids are heated by means of combustion reactions in one of the fluidised beds in the proposed dual fluidised bed design. An overflow standpipe is then used to transport the solids to a second fluidised bed in order to provide the energy required for the endothermic pyrolysis reactions. The cooler solids are then fed back to the combustion fluidised bed by means of a screw-conveyor, creating a circulating system. A two-stage model was used to model the pyrolysis reactions. In this model, the wood is converted to bio-char, syngas and tar compounds. The tar compounds are the desired product as they can be condensed to form liquid bio-oil. However, these compounds undergo a second reaction in the gas phase in which they are converted to bio-char and syngas. It is therefore necessary to quench these gases rapidly in order to maximise the yield of bio-oil obtained from the system. Bio-oil is a source of many high-value chemicals and can also be upgraded to produce liquid bio-fuels. A portion of the syngas is recycled back to the pyrolysis fluidised bed in order to fluidise the bed. In this way, oxygen is prevented from entering the pyrolysis fluidised bed, which would cause the biomass in the bed to undergo combustion rather than pyrolysis. The operating temperatures of the combustion and pyrolysis fluidised beds were optimised at 900°C and 500°C respectively. A cold unit of the system was built at the Agricultural Research Service in Wyndmoor, Pennsylvania, USA. From the experiments performed on this unit it was found that the solid transport mechanism designed during the project is suitable for the pyrolysis of biomass process. In addition, the solids circulation rate between the two beds was easy to control, which is necessary in order to maximise the yield of bio-oil obtained from the system. A pilot-scale unit of the dual fluidised bed design was built in order to finalise the design and ensure that it could be scaled up. This system included all the downstream units, which had to be designed for the dual fluidised bed system. Several cold-run experiments were also performed on the pilot-scale system in order to ensure that it would perform as required during operation. It was found that the combustion fluidised bed could be fluidised as required and that the circulation of solids between the combustion and pyrolysis fluidised beds functioned well and could be easily controlled. Therefore, it was concluded that the proposed dual fluidised bed system is suitable for the pyrolysis of biomass process and is a feasible reactor system for the large-scale pyrolysis of biomass. The large-scale operation of the proposed dual fluidised bed system offers several advantages, particularly within the forestry sector. These advantages have important implications, as follows: <ul> <li> The current research offers the opportunity for the forestry sector to shift its focus from the production of traditional wood products, such as pulp and paper, to products such as specialised chemicals.</li> <li> The bio-oil produced in the dual fluidised bed system can be upgraded to renewable liquid fuels, which may help reduce the dependence of the infrastructure on fossil fuels.</li> <li> The dual fluidised bed system provides an opportunity for capturing and removing CO2 from the atmosphere in the form of bio-char. It is therefore considered to be a carbon-negative process, and may help reduce the concentration of greenhouse gases.</li> <li> The bio-char produced in the dual fluidised bed system can be used to feed nutrients back to plantation floors in the forestry sector, thereby aiding the growth of further plantations.</li></ul> Copyright / Dissertation (MEng)--University of Pretoria, 2013. / Chemical Engineering / unrestricted

In the near future, biomass-derived energy is predicted to substantially complement that generated from petroleum. However, certain types of biomass employed as substrates in the microorganism-mediated production of renewable fuelethanol contain significant amounts of the recalcitrant hexose sugar galactose. The consumption of galactose in hexose sugar-fermenting yeasts is often delayed with respect to other sugars, such as glucose and mannose, because of an intrinsic preference for carbon sources requiring less energy in the preparatory reactions preceding glycolysis. This work comprised the search for, and characterization of anethanologenic yeast capable of efficiently assimilating galactose. Screening experiments conducted with wild-type Saccharomyces cerevisiae strains identified one isolate (Y-1528) exhibiting exceptionally fast galactose fermentation. The absence of conventional glucose repression, including a preference for galactose as carbon source and notable delays in the utilization of glucose and mannose, was demonstrated in mixed sugar fermentations. Endogenous extracellular glucose was observed during double sugar fermentations of galactose and mannose. This glucose was traced to supplied galactose by radioisotope labeling, suggesting involvement of UDP-galactose 4-epimerase in the responsible reaction mechanism(s).Sub-cellular fractionation was employed in an attempt to ascertain enzyme localization in Y-1528. Fermentations of lignocellulosic substrate mixtures by Y-1528 illustrated better performance than that accomplished by a reference yeast strain, and again showed a preference for galactose. Mixed cultures of Y-1528 and the same reference strain demonstrated accelerated hexose sugar consumption, and no detrimental effects from competition, during synthetic and lignocellulosic substrate fermentations. Glucose repression was absent in mixed culture fermentations. Fermentations of synthetic sugar mixtures augmented with lignocellulosic inhibitory compounds showed Y-1528 to have better performance than a reference yeast strain, despite a global detrimental effect relative to inhibitor-free fermentations. Cell recycle batch fermentations of spent sulfite liquor illustrated the toxic effect of the hardwood variant, as well as a net loss of performance from all strains tested. Y-1528 was taxonomically confirmed as S. cerevisiae. UDP-galactose 4-epimerase chromatographic purification was unsuccessful, but a partial sequence of the enzyme, showing complete identity with type sequence, was obtained by electrophoretic separation, liquid chromatography, and mass spectrometry. A significantly mutated UDP-galactose 4-epimerase gene was successfully sequenced. / Forestry, Faculty of / Graduate

The search for alternative energy sources has increased interests in forest biomass. During the last few years, the sever infestation of the Mountain Pine Beetle (MPB) within the Interior BC forests has led to huge volumes of dead wood that exceed the capacity of the lumber industry. One way to make the most value of the surplus wood is to use it as the feedstock for bioenergy. The forest biomass can be supplied through conventional (roadside residuals), full-tree chipping, or satellite yard systems. This thesis presents the development of a simulation model of supply logistics of forest biomass and its application to a case of supplying MPB-killed biomass from Quesnel Timber Supply Area (one of the most infested areas in the Interior BC) to a potential 300 MW power plant adjacent to the city of Quesnel. The model has the ability of providing estimates of quantity, delivery cost, and moisture content of biomass which are critical in feasibility study of any bioenergy project. The results obtained from simulation model showed a delivery cost of C$45 per oven dry tonne of wood chips to the power plant. The results also revealed that the feedstock recovered from roadside residues in one year meets about 30% of the annual demand of the power plant. Potential increase in the Allowable Annual Cut (AAC) for Quesnel TSA increases the quantity of biomass supplied from roadside residuals. However, as long as the biomass is supplied only through conventional harvesting, increasing the AAC even by 40% does not provide enough feedstock to meet the annual demand of the plant. Using the simulation modeling, this research has the benefit of considering the logistics of forest biomass supply as an integrated and interacting system as well as providing different critical parameters over time. The model also has the potential of considering dynamic and random behavior of the logistics system of supplying forest biomass. The model can be modified and applied to similar cases of conventional forest biomass supply. It also can be extended to other harvesting systems including satellite yard and whole-tree chipping. / Forestry, Faculty of / Graduate

In this work the combustion characteristics of coal, charcoal, microalgae biomass and blends between these three components were evaluated by means of non-isothermal thermogravimetry. Blends between coal, charcoal and microalgae biomass were made according to the specifications of a D-optimal mixture design so as to be able to model interactions between the three components with maximum precision despite multiple constraints built into the design. These constraints specified that coal can have a minimum value of 70 mass percent in any blend, while microalgae can have a maximum value of 20 mass percent. While coal and charcoal were blended by mixing the two respective dry components, microalgae biomass was incorporated into the blends by first absorbing microalgae onto fine coal from concentrated slurry of the microalgae in water. The microalgae in these blends were therefore intimately associated with the coal. This approach differed substantially from the normal practice of preparing coal – biomass blends (which are usually dry-mixed as for coal – charcoal blends). Proximate analyses of the starting materials showed that the microalgae biomass has a significantly higher volatile matter: fixed carbon content than both coal and charcoal, which should improve the combustion of these materials by providing a more stable combustion flame. Analyses of the thermogravimetric data obtained showed that coal and charcoal have much simpler combustion profiles than microalgae biomass for which five different thermal events could be observed in the DTG combustion profile. Qualitative kinetic analyses showed that the combustion of coal and charcoal follows first-order kinetics, but for microalgae biomass combustion, the first two combustion stages appear to follow first-order kinetics. The TG and DTG profiles for coal, charcoal, microalgae and blends of these three components were used to derive values for the so-called comprehensive combustion property index (S-value), which provides a combined measure of the ease of ignition, rate of combustion, and burn-out temperature. The S-values so obtained were used as response variable for the construction of a response surface model in the experimental domain investigated. Following statistical validation of the response surface model, the model was used to predict an optimum S-value or a blend that would display optimum combustion behaviour. Two optimum blends were obtained from the optimisation process, one in which only charcoal is added to coal, and one in which only microalgae is added to coal. Adding both charcoal and microalgae produced an antagonistic effect compared to when only one of these are used. Qualitative kinetic analyses of the combustion data of blends indicate that blends of coal and charcoal combust in a manner similar to the individual components (hence following first-order kinetics), but blends of coal and microalgae follow more complex kinetics despite the fact that the combustion profile is visibly more simple compared to the combustion profile for microalgae alone.

Extensive consumption of carbon resources has led to decreasing reserves of fossil fuels and growing concern about global warming. This dilemma has promoted a shift in the economy to develop new long-term, environmentally friendly, and sustainable sources for fuels and chemicals to replace fossil fuel-based sources. Renewable biomass is an ideal alternative, as it is abundant, and relatively cheap. Among current biofuel resources, 5-hydroxymethylfurfural (5-HMF) is a versatile intermediate between biomass-based carbohydrate chemistry and fossil fuel-based industrial organic chemistry, which can be used to synthesize a broad range of chemicals that are currently derived from fossil fuel-based resources. Carbohydrates became the preferred feedstock for high yield production of 5-HMF, and the most convenient route for the synthesis of 5-HMF is the acid-catalyzed dehydration of hexose. Within this context, a variety of processes were developed for the synthesis of 5-HMF from dehydration of fructose involving various solvents, including water, organic solvents, and biphasic systems. Likewise, a range of catalysts were employed, such as homogeneous acid catalysts and metal chlorides, which showed high catalytic activity. Heterogeneous catalysts have also been receiving attention due to their advantages such as easy recovery and recyclability. In the current research, microwave-assisted synthesis of 5-HMF by dehydration of fructose over various acidic porous catalysts, such as periodic mesoporous organosilica (PMO), carbon materials, and metal organic frameworks (MOFs), was investigated. The results showed that the obtained 5-HMF yields were satisfactory, and more importantly highlighted some of the properties of porous heterogeneous catalysts that may improve the production of 5-HMF.

Of the many thermochemical conversion pathways for utilizing biomass as a renewable energy source, fast pyrolysis is a promising method for converting and upgrading carbonaceous feedstocks into a range of liquid fuels for use in heat, electricity and transportation applications. Experimental trials have been carried out to assess the impact of operational parameters on process yields. However, dealing with larger-scale experimental systems comes at the expense of lengthy and resource-intensive experiments. Luckily, the advances in computing technology and numerical algorithm solvers have allowed reactor modelling to be an attractive opportunity for reactor design, optimization and experimental data interpretation in a cost-effective fashion. In this work, a fluidized bed reactor model for biomass fast pyrolysis was developed and applied to the Bell’s Corners Complex (BCC) fluidized bed fast pyrolysis unit located at NRCan CanmetENERGY (Ottawa, Canada) for testing and validation. The model was programmed using the Microsoft Visual Basic for Applications software with the motivation of facilitating use and accessibility as well as minimizing runtime and input requirements. The application of different biomass devolatilization schemes within the model was conducted, not only for biomass fast pyrolysis product quantity but also liquid product composition (quality), to examine the effect of variable reaction kinetic sub-models on product yields. The model predictions were in good agreement with the results generated from the experimental work and mechanism modifications were proposed which further increased the accuracy of model predictions. Successively, the formulation of the modelled fluid dynamic scheme was adapted to study the effect of variable hydrodynamic sub-models on product yields for which no significant effect was observed. The work also looked into effect of the dominant process variables such as feedstock composition, bed temperature, fluidizing velocity and feedstock size on measurable product outputs (bio-oil, gas and biochar) and compared the results to those generated from the experimental fast pyrolysis unit. The ideal parameters for maximizing bio-oil yield have been determined to be those which: minimize the content of lignin and inorganic minerals in the feedstock, maintain the dense-bed temperature in a temperature range of 450-520 ºC, maximize the fluidization velocity without leading to bed entrainment, and limit the feedstock particle size to a maximum of 2000 μm.

woodenThe Energetic consumption of each kind of energy grows with the development of society and industrialization. Major influence has the world population, which is having growing tendencies. The most important source of primary energy is the rock-oil, the second important source of energy is coal, followed by natural gas. Regarding to the fact that these commodities cannot be renewed, it is clear that it can be uncontrollably wasted. There is emerging a space for new possibilities such as the energy of future -- renewable sources of energy, which are taking the fourth place in the importance of the world and it's energy sources. It is mainly biomass, water, solar or wind energy. This diploma thesis is aiming at the production of biomass -- pellets, which are a biological source of energy (wooden or vegetative material) with number of positive features and parameters. The main objective of this diploma thesis is to offer excursion into another space of modern thinking, which is well-founded by economical facts and also explains the need of taking into the consideration other alternative energetic types, which should be a common thing in future.

Fluidization of biomass particles is an important process in the gasification, pyrolysis and combustion in order to extract energy from biomass. Studies on the fluidization of biomass particles (corn cob and walnut shell), inert particles (sand, glass bead, and alumina), which are added to facilitate fluidization of biomass, and biomass/sand mixture were performed. Experiments were carried out in a 14.5 cm internal diameter cold flow fluidization bed to determine minimum fluidization velocities with air as fluidizing medium. On the of basis of experimental data from both present work and those found in the literature, new correlations were developed to predict minimum fluidization velocity for inert particles as well as biomass particles. It was found that the proposed correlations satisfactorily predict minimum fluidization velocities and was in well agreement with experimental data. Furthermore, effect of weight percentage of biomass in the biomass/sand mixtures was studied. The weight fraction of biomass particles in the mixture was chosen in the range of 0 ~ 100 wt. %. The results show that minimum fluidization velocity of the mixtures increases with an increase in biomass content. Using the present experimental data, a new correlation was developed in terms of mass ratio for predicting values of minimum fluidization velocity of these mixtures. However, the validity of the proposed correlation should be further studied by conducting more experiments using the biomass/sand mixtures of different particle size, shape, and density.

>Magister Scientiae - MSc / Biofuels are currently recognised as the most viable source of energy to replace depleting fossil fuel reserves, with bioethanol the most popular alternative alcohol fuel. Producing bioethanol from agricultural waste residues is a feasible socio-economic industrial process. Lignocellulose, from which plant material is composed, is highly recalcitrant to enzymatic degradation and therefore requires a suite of enzymes for complete hydrolysis of the biomass. Metagenomes, particularly from extreme environments, represent an unlimited resource for the discovery of novel biocatalysts for inclusion in industrial processes. Here we report on the cloning and functional characterisation of a novel thermophilic cellulase identified by the functional screening of a Malawian, hotspring sediment metagenomic library. The gene encoding the cellulase, celMHS, composed of 2,705 nucleotides and encoded a polypeptide of 905 amino acids with a predicted molecular mass of about 98 kDa. The in silico translated protein, CelMHS, contained a putative transmembrane domain, a family 4 carbohydrate binding motive (CBM 4), a truncated glycoside hydrolase family 42 (GH42) domain and a N-terminal region that does not have sequence similarity to any previously described domains. Functional characterisation of the recombinant CelMHS demonstrated that the protein displayed an optimal pH of 6.0 and temperature of 100°C. CelMHS had high specific activity toward substrates comprising of β-1,4 linked glucose subunits such as carboxymethyl cellulose, β-D-glucan from barley and lichenan, however, some activity was also observed against avicel, a crystalline cellulose substrate. HPLC analysis of the hydrolysis products produced by CelMHS indicates that this particular enzyme prefers longer chain oligosaccharides. This is, to the best of our knowledge, the first investigation describing the cloning and characterization of a carbohydrate hydrolysing enzyme comprised of the unique sequence architecture: a partial GH42 catalytic domain, a CBM 4 and a unique N-domain sequence. Key words: cellulose, cellulases, lignocellulosic biomass, bioethanol, saccharification, hydrolysis, metagenomic library, thermophilic

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13347号 / 論農博第2890号 / 新制||農||1080(附属図書館) / 学位論文||R2||N5254(農学部図書室) / (主査)教授 杉山 淳司, 教授 髙部 圭司, 教授 渡邊 隆司 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM