Synthetic membranes have a high separation efficiency, small footprint, low energy consumption and ease of operation, making them an attractive alternative to traditional separation operations. For this reason, membranes have been extensively studied for the treatment and recycling of bitumen-containing wastewaters. Such wastewaters include petroleum produced water, residual pipeline cleaning solutions and contaminated water from oil spills. Ceramic membranes are preferred in these applications over polymeric membranes because they are highly resistant to solvents and can be operated at high temperatures over a wide range of pH. Fine clays and silicates, coated with bitumen, are significant foulants for membrane filtration systems. These foulants possess acidic, basic and amphoteric groups, leading to the presence of both positive and negative surface charges. Ceramic membranes in aqueous media have a pH dependent surface charge. It was hypothesized that these surface charges are responsible for the high fouling of ceramic membranes that is observed when treating wastewaters containing bituminous fines. The overall objective of this research was to reduce fouling and increase the lifetime of ceramic membranes in treating oil sands produced water; an example of a wastewater containing bituminous fines. This goal was achieved through the surface modification of the ceramic membrane’s selective layer, as well as by the implementation of a novel in-place steam regeneration technique. All membrane filtration tests were performed with field samples of oil sands produced water that were supplied to CanmetMINING (NRCan) by three Canadian oil sands companies. Organosilanes are silicon-based monomers that can possess a wide array of chemical functionality due to their organic moieties. They are capable of reacting with oxide surfaces, and have seen extensive use as surface modification agents for ceramic membranes in various applications. To maintain desirable hydrophilic properties without surface charges, highly hydrophilic and non-ionic polyethylene oxide (PEO) based organosilanes were identified. These PEO-silanes were then used to modify ceramic membranes of several different selective layer materials, and the thermal stability of the silane layer was studied using FTIR, SEM, zeta potential and contact angle measurements. The modification procedure with PEO-silanes was first applied to lab-scale membrane disks, and subsequently to commercial scale multilumen membrane tubes that were tested in a pilot-scale system at CanmetMINING. Results obtained from both sets of experiments were promising and demonstrate that ceramic membranes can be surface modified in a way that successfully renders them fouling resistant to the bituminous fines present in these wastewaters. Upon surface modification, foulants were more readily released from the membrane surface, resulting in an enhanced flux and separation performance. A novel steam regeneration technique was also applied as a means of bituminous fouling alleviation. This technique was tested in the CanmetMINING pilot-scale system and consisted of periodically injecting steam into the membrane lumen feed channels during operation. Direct steam injection rapidly heated foulant cake layers, and water droplets in the saturated steam caused surface abrasions that ultimately resulted in the scouring of bitumen away from the membrane surface. Membrane fluxes when steam regeneration was active were up to 4 times higher when compared to tests where only traditional permeate backflushing was used. The fouling remediation techniques developed in this work have broad potential applicability in ceramic membrane filtration systems aimed at treating all wastewaters containing bituminous compounds, such as process waters in general and contaminated water from oil spills.

The current study examined a method of language sampling (the Dixit Method- Science, Math, Engineering, Arts, and Math) in early adolescents with typically developing language. The purpose of this study was to examine the effectiveness of the DM-STEAM in eliciting lexically sophisticated spoken language samples in the early adolescent population. To examine lexical sophistication, traditional measures of analysis such as mean length of utterance (MLU) and average type token ratio (AVG TTR) were applied along with a measure of low frequency vocabulary. To compare performance on the DM-STEAM, school standardized assessments were obtained to measure student skill in academic content areas. Twenty-two student participants in the sixth grade (11 years to 12 years 11 months) were recruited from a local elementary school. The data was evaluated using a paired tailed t test and a path analysis test. Although the sample size is small, results from the study indicate the DM-STEAM elicits low frequency academic vocabulary in early adolescent populations.

In turbomachinery, extra excitation forces may result from non-idealised operation conditions and may sometime cause excessive vibrations and unsteady rotor motions. The goal of this thesis is to investigate the effects of such excitation forces. The extra excitation forces investigated here are the Thomas/Alford force due to the blade tip clearance change, the steam excitation force caused by the variation of inlet steam speed and state blade trailing wake and the dominant magnetic pull force due to dynamic eccentricity of the rotor. The main research results in this thesis include: (1) The modelling of the Jeffcott rotor and the 600MW steam-turbine generator. The used in-house ??transient?? program can only handle the circular short bearings with the modified short bearing method while the simulated steam-turbine should be supported by tilting pad bearings. The first critical speeds of systems supported by tilting pad bearings are more approaching to the lab data for all four rotor models while that of journal bearing supported systems are normally lower than the real operating critical speed. (2) Applying three sorts of excitation forces into the single-stage rotor-bearing system. The numerical simulation shows that for the model with each single excitation force, all of these three forces need to reach some limit to force the system into the unsteady state. For all the three forces, higher limits are needed if the machine runs at lower running speeds. Furthermore, unbalance loading also can influence the system behaviours. As the unbalance increases, the system will still stay steady while the spectra become noisier, though the amplitude still low comparing to harmonics. (3) Combing three types of excitation forces into the assembled rotor-bearing system. The numerical simulation shows that the assembled system presents similar vibration responses as the single stage rotor-bearing system. Furthermore, these three forces cannot cancel each other and the combination will unstabilise the system. Meanwhile, the influence of the dominant magnetic pull force is less than other two forces.

Doctor of Philosophy / Steam reconditioning to recover collapse, in mid to low density eucalypt species, has been known for over ninety years. The current industrial practices for steam reconditioning have largely been based on a few older studies, which were often poorly documented and based on very small sample sizes. On top of this, many local practices and ‘rules of thumb’ have developed over time, many of which have a questionable scientific basis. This thesis was undertaken to more rigorously investigate and fundamentally understand collapse recovery, and try to optimise its application. The most obvious variable that kiln operators have control over is the moisture content of the timber prior to steam reconditioning. Experiments were undertaken to generate a range of moisture gradients (ranging from minimal to more industrially realistic) to evaluate the effect of moisture content on collapse recovery. An optimal moisture content for the core of the boards was found to be between about 18–20%, although there was no statistical difference in recoveries between about 17–25% moisture content. Below 15% moisture content recovery dropped off severely and intra-ring internal checking closure was incomplete, while at 25% moisture content an increased level of normal shrinkage, due to the early removal of drying stresses, was the main drawback. Above a core moisture content of about 35% incomplete closure of intra-ring internal checks was again observed. There was little evidence of re-collapse occurring in these high moisture content samples. Previously established relationships between density and collapse and drying rate were again generally observed in these experiments. However, for the first time an effect of collapse in reducing the fitted drying diffusion coefficients was also observed. It was also observed that, provided the moisture content of the board was in the critical range, most of the collapse recovery was achieved in the time it took to get the core of the board up to the steaming temperature of close to 100°C. This suggests that for most thicknesses a conservative reconditioning period of two hours at temperature is all that is required. This recommended shortening of the reconditioning cycle could dramatically increase the throughput of timber through the steam reconditioning chambers. Alternatively, it could mean that where modern final drying kilns are being used, the reconditioning treatment could be carried out within the final drying kiln. A finite element model was developed to demonstrate the mechanism by which collapse recovery occurs. The theory tested was that the elastic component that stores the energy to restore the shape of the deformed cell is primarily found in the S1 and S3 layers. In contrast, the inelastic component is primarily found in the S2 layer. The model generated here provided limited support for this theory.

Thesis (M.S.)--Virginia Polytechnic Institute, 1951. / Abstract. Vita. Includes bibliographical references (leaves 30-31). Also available via the Internet.

Glycerol is a waste by-product obtained during the production of biodiesel. Biodiesel is one of the alternative fuels used to meet our energy requirements and also carbon dioxide emission is much lesser when compared to regular diesel fuel. Biodiesel and glycerol are produced from the transesterification of vegetable oils and fats with alcohol in the presence of a catalyst. About 10 wt% of vegetable oil is converted into glycerol during the transesterification process. An increase in biodiesel production would decrease the world market price of glycerol. The objective of this work is to produce value added products such as hydrogen or syn gas and medium heating value gas from waste glycerol using pyrolysis and steam gasification processes. <p> Pyrolysis and steam gasification of glycerol reactions was carried out in an Inconel®, tubular, fixed bed down-flow reactor at atmospheric pressure. The effects of carrier gas flow rate (30mL/min-70mL/min), temperature (650oC-800oC) and different particle diameter of different packing material (quartz - 0.21-0.35mm to 3-4mm; silicon carbide 0.15 to 1mm; Ottawa sand 0.21-0.35mm to 1.0-1.15mm) on the product yield, product gas volume, composition and calorific value were studied for the pyrolysis reactions. An increase in carrier gas flow rate did not have a significant effect on syn gas production at 800oC with quartz chips diameter of 3-4mm. However, total gas yield increased from 65 to 72wt% and liquid yield decreased from 30.7 to 19.3wt% when carrier gas flow rate decreased from 70 to 30mL/min. An increase in reaction temperature, increased the gas product yield from 27.5 to 68wt% and hydrogen yield from 17 to 48.6mol%. Also, syn gas production increased from 70 to 93 mol%. A change in particle size of the packing material had a significant increase in the gas yield and hydrogen gas composition. Therefore, pyrolysis reaction at 800oC, 50mL/min of nitrogen and quartz particle diameter of 0.21-0.35mm were optimum reaction parameter values that maximise the gas product yield (71wt%), hydrogen yield (55.4mol%), syn gas yield (93mol%) and volume of product gas (1.32L/g of glycerol). The net energy recovered at this condition was 111.18 kJ/mol of glycerol fed. However, the maximum heating value of product gas (21.35 MJ/m3) was obtained at 650oC, 50mL/min of nitrogen and with a quartz packing with particle diameter of 3-4mm. <p>The steam gasification of glycerol was carried out at 800oC, with two different packing materials (0.21-0.35mm diameter of quartz and 0.15mm of silicon carbide) by changing the steam to glycerol weight ratio from 0:100 to 50:50. The addition of steam to glycerol increased the hydrogen yield from 55.4 to 64mol% and volume of the product gas from 1.32L/g for pyrolysis to 1.71L/g of glycerol. When a steam to glycerol weight ratio of 50:50 used for the gasification reaction, the glycerol was completely converted to gas and char. Optimum conditions to maximize the volume of the product gas (1.71L/g), gas yield of 94wt% and hydrogen yield of 58mol% were 800oC, 0.21-0.35mm diameter of quartz as a packing material and steam to glycerol weight ratio of 50:50. Syn gas yield and calorific value of the product gas at this condition was 92mol% and 13.5MJ/m3, respectively. The net energy recovered at this condition was 117.19 kJ/mol of glycerol fed. <p>The steam gasification of crude glycerol was carried out at 800oC, quartz size of 0.21-0.35mm as a packing material over the range of steam to crude glycerol weight ratio from 7.5:92.5 to 50:50. Gasification reaction with steam to glycerol weight ratio of 50:50 was the optimum condition to produce high yield of product gas (91.1wt%), volume of gas (1.57L/g of glycerol and methanol), hydrogen (59.1mol%) and syn gas (79.1mol%). However, the calorific value of the product gas did not change significantly by increasing the steam to glycerol weight ratio.

Densification of biomass is often necessary to combat the negative storage and handling characteristics of these low bulk density materials. A consistent, high-quality densified product is strongly desired, but not always delivered. Within the context of pelleting and briquetting, binding agents are commonly added to comminuted biomass feedstocks to improve the quality of the resulting pellets or briquettes. Many feedstocks naturally possess such binding agents; however, they may not be abundant enough or available in a form or state to significantly contribute to product binding. Also, process parameters (pressure and temperature) and material variables (particle size and moisture content) can be adjusted to improve the quality of the final densified product.<p>Densification of ground biomass materials is still not a science, as much work is still required to fully understand how the chemical composition and physical properties, along with the process variables, impact product quality. Generating densification and compression data, along with physical and mechanical properties of a variety of biomass materials will allow for a deeper understanding of the densification process. This in turn will result in the design of more efficient densification equipment, thus improving the feasibility of using biomass for chemical and energy production.<p>Experiments were carried out wherein process (pressure and temperature) and material (particle size and moisture content) variables were studied for their effect on the densification process (compression and relaxation characteristics) and the physical quality of the resulting products (pellets). Two feedstocks were selected for the investigation; namely, poplar wood and wheat straw, two prominent Canadian biomass resources. Steam explosion pretreatment was also investigated as a potential method of improving the densification characteristics and binding capacity of the two biomass feedstocks.<p> Compression/densification and relaxation testing was conducted in a closed-end cylindrical die at loads of 1000, 2000, 3000, and 4000 N (31.6, 63.2, 94.7, and 126.3 MPa) and die temperatures of 70 and 100°C. The raw poplar and wheat straw were first ground through a hammer mill fitted with 0.8 and 3.2 mm screens, while the particle size of the pretreated poplar and wheat straw was not adjusted. The four feedstocks (2 raw and 2 pretreated) were also conditioned to moisture contents of 9 and 15% wb prior to densification. <p> Previously developed empirical compression models fitted to the data elucidated that along with particle rearrangement and deformation, additional compression mechanisms were present during compression. Also, the compressibility and asymptotic modulus of the biomass grinds were increased by increasing the die temperature and decreasing product moisture content. While particle size did not have a significant effect on the compressibility, reducing it increased the resultant asymptotic modulus value. Steam explosion pretreatment served to decrease the compressibility and asymptotic modulus of the grinds.<p>In terms of physical quality of the resulting product, increasing the applied load naturally increased the initial density of the pellets (immediately after removal from the die). Increasing the die temperature served to increase the initial pellet density, decrease the dimensional (diametral and longitudinal) expansion (after 14 days), and increase the tensile strength of the pellets. Decreasing the raw feedstock particle size allowed for the increase in initial pellet density, decrease in diametral expansion (no effect on longitudinal expansion), and increase in tensile strength of the pellets. Decreasing the moisture content of the feedstocks allowed for higher initial pellet densities, but also an increased dimensional expansion. The pretreated feedstocks generally had higher initial pellet densities than the raw grinds. Also, the pretreated feedstocks shrank in diameter and length, and had higher tensile strengths than the raw feedstocks. The high performance of the pretreated poplar and wheat straw (as compared to their raw counterparts) was attributed to the disruption of the lignocellulosic structure, and removal/hydrolysis of hemicellulose, during the steam pretreatment process which was verified by chemical and Fourier transform infrared analysis. As a result, a higher relative amount of lignin was present. Also, the removal/hydrolysis of hemicellulose would indicate that this lignin was more readily available for binding, thus producing superior pellets.

Glycerol is a waste by-product obtained during the production of biodiesel. Biodiesel is one of the alternative fuels used to meet our energy requirements and also carbon dioxide emission is much lesser when compared to regular diesel fuel. Biodiesel and glycerol are produced from the transesterification of vegetable oils and fats with alcohol in the presence of a catalyst. About 10 wt% of vegetable oil is converted into glycerol during the transesterification process. An increase in biodiesel production would decrease the world market price of glycerol. The objective of this work is to produce value added products such as hydrogen or syn gas and medium heating value gas from waste glycerol using pyrolysis and steam gasification processes. <p> Pyrolysis and steam gasification of glycerol reactions was carried out in an Inconel®, tubular, fixed bed down-flow reactor at atmospheric pressure. The effects of carrier gas flow rate (30mL/min-70mL/min), temperature (650oC-800oC) and different particle diameter of different packing material (quartz - 0.21-0.35mm to 3-4mm; silicon carbide 0.15 to 1mm; Ottawa sand 0.21-0.35mm to 1.0-1.15mm) on the product yield, product gas volume, composition and calorific value were studied for the pyrolysis reactions. An increase in carrier gas flow rate did not have a significant effect on syn gas production at 800oC with quartz chips diameter of 3-4mm. However, total gas yield increased from 65 to 72wt% and liquid yield decreased from 30.7 to 19.3wt% when carrier gas flow rate decreased from 70 to 30mL/min. An increase in reaction temperature, increased the gas product yield from 27.5 to 68wt% and hydrogen yield from 17 to 48.6mol%. Also, syn gas production increased from 70 to 93 mol%. A change in particle size of the packing material had a significant increase in the gas yield and hydrogen gas composition. Therefore, pyrolysis reaction at 800oC, 50mL/min of nitrogen and quartz particle diameter of 0.21-0.35mm were optimum reaction parameter values that maximise the gas product yield (71wt%), hydrogen yield (55.4mol%), syn gas yield (93mol%) and volume of product gas (1.32L/g of glycerol). The net energy recovered at this condition was 111.18 kJ/mol of glycerol fed. However, the maximum heating value of product gas (21.35 MJ/m3) was obtained at 650oC, 50mL/min of nitrogen and with a quartz packing with particle diameter of 3-4mm. <p>The steam gasification of glycerol was carried out at 800oC, with two different packing materials (0.21-0.35mm diameter of quartz and 0.15mm of silicon carbide) by changing the steam to glycerol weight ratio from 0:100 to 50:50. The addition of steam to glycerol increased the hydrogen yield from 55.4 to 64mol% and volume of the product gas from 1.32L/g for pyrolysis to 1.71L/g of glycerol. When a steam to glycerol weight ratio of 50:50 used for the gasification reaction, the glycerol was completely converted to gas and char. Optimum conditions to maximize the volume of the product gas (1.71L/g), gas yield of 94wt% and hydrogen yield of 58mol% were 800oC, 0.21-0.35mm diameter of quartz as a packing material and steam to glycerol weight ratio of 50:50. Syn gas yield and calorific value of the product gas at this condition was 92mol% and 13.5MJ/m3, respectively. The net energy recovered at this condition was 117.19 kJ/mol of glycerol fed. <p>The steam gasification of crude glycerol was carried out at 800oC, quartz size of 0.21-0.35mm as a packing material over the range of steam to crude glycerol weight ratio from 7.5:92.5 to 50:50. Gasification reaction with steam to glycerol weight ratio of 50:50 was the optimum condition to produce high yield of product gas (91.1wt%), volume of gas (1.57L/g of glycerol and methanol), hydrogen (59.1mol%) and syn gas (79.1mol%). However, the calorific value of the product gas did not change significantly by increasing the steam to glycerol weight ratio.

Densification of biomass is often necessary to combat the negative storage and handling characteristics of these low bulk density materials. A consistent, high-quality densified product is strongly desired, but not always delivered. Within the context of pelleting and briquetting, binding agents are commonly added to comminuted biomass feedstocks to improve the quality of the resulting pellets or briquettes. Many feedstocks naturally possess such binding agents; however, they may not be abundant enough or available in a form or state to significantly contribute to product binding. Also, process parameters (pressure and temperature) and material variables (particle size and moisture content) can be adjusted to improve the quality of the final densified product.<p>Densification of ground biomass materials is still not a science, as much work is still required to fully understand how the chemical composition and physical properties, along with the process variables, impact product quality. Generating densification and compression data, along with physical and mechanical properties of a variety of biomass materials will allow for a deeper understanding of the densification process. This in turn will result in the design of more efficient densification equipment, thus improving the feasibility of using biomass for chemical and energy production.<p>Experiments were carried out wherein process (pressure and temperature) and material (particle size and moisture content) variables were studied for their effect on the densification process (compression and relaxation characteristics) and the physical quality of the resulting products (pellets). Two feedstocks were selected for the investigation; namely, poplar wood and wheat straw, two prominent Canadian biomass resources. Steam explosion pretreatment was also investigated as a potential method of improving the densification characteristics and binding capacity of the two biomass feedstocks.<p> Compression/densification and relaxation testing was conducted in a closed-end cylindrical die at loads of 1000, 2000, 3000, and 4000 N (31.6, 63.2, 94.7, and 126.3 MPa) and die temperatures of 70 and 100°C. The raw poplar and wheat straw were first ground through a hammer mill fitted with 0.8 and 3.2 mm screens, while the particle size of the pretreated poplar and wheat straw was not adjusted. The four feedstocks (2 raw and 2 pretreated) were also conditioned to moisture contents of 9 and 15% wb prior to densification. <p> Previously developed empirical compression models fitted to the data elucidated that along with particle rearrangement and deformation, additional compression mechanisms were present during compression. Also, the compressibility and asymptotic modulus of the biomass grinds were increased by increasing the die temperature and decreasing product moisture content. While particle size did not have a significant effect on the compressibility, reducing it increased the resultant asymptotic modulus value. Steam explosion pretreatment served to decrease the compressibility and asymptotic modulus of the grinds.<p>In terms of physical quality of the resulting product, increasing the applied load naturally increased the initial density of the pellets (immediately after removal from the die). Increasing the die temperature served to increase the initial pellet density, decrease the dimensional (diametral and longitudinal) expansion (after 14 days), and increase the tensile strength of the pellets. Decreasing the raw feedstock particle size allowed for the increase in initial pellet density, decrease in diametral expansion (no effect on longitudinal expansion), and increase in tensile strength of the pellets. Decreasing the moisture content of the feedstocks allowed for higher initial pellet densities, but also an increased dimensional expansion. The pretreated feedstocks generally had higher initial pellet densities than the raw grinds. Also, the pretreated feedstocks shrank in diameter and length, and had higher tensile strengths than the raw feedstocks. The high performance of the pretreated poplar and wheat straw (as compared to their raw counterparts) was attributed to the disruption of the lignocellulosic structure, and removal/hydrolysis of hemicellulose, during the steam pretreatment process which was verified by chemical and Fourier transform infrared analysis. As a result, a higher relative amount of lignin was present. Also, the removal/hydrolysis of hemicellulose would indicate that this lignin was more readily available for binding, thus producing superior pellets.

Concentrated animal feeding operations such as cattle feedlots and dairies produce a large amount of manure, cattle biomass (CB), which may lead to land, water, and air pollution if waste handling systems and storage and treatment structures are not properly managed. However, the concentrated production of low quality CB at these feeding operations serves as a good feedstock for in situ gasification for syngas (CO and H2) production and subsequent use in power generation. A small scale (10 kW) countercurrent fixed bed gasifier was rebuilt to perform gasification studies under quasisteady state conditions using dairy biomass (DB) as feedstock and various air-steam mixtures as oxidizing sources. A DB-ash (from DB) blend and a DB-Wyoming coal blend were also studied for comparison purposes. In addition, chlorinated char was also produced via pure pyrolysis of DB using N2 and N2-steam gas mixtures. The chlorinated char is useful for enhanced capture of Hg in ESP of coal fired boilers. Two main parameters were investigated in the gasification studies with air-steam mixtures. One was the equivalence ratio ER (the ratio of stochiometric air to actual air) and the second was the steam to fuel ratio (S:F). Prior to the experimental studies, atom conservation with i) limited product species and ii) equilibrium modeling studies with a large number of product species were performed on the gasification of DB to determine suitable range of operating conditions (ER and S:F ratio). Results on bed temperature profile, gas composition (CO, CO2, H2, CH4, C2H6, and N2), gross heating value (HHV), and energy conversion efficiency (ECE) are presented. Both modeling and experimental results show that gasification under increased ER and S:F ratios tend to produce rich mixtures in H2 and CO2 but poor in CO. Increased ER produces gases with higher HHV but decreases the ECE due to higher tar and char production. Gasification of DB under the operating conditions 1.59<ER less than6.36 and 0.35<s:f>less than0.8 yielded gas mixtures with compositions as given below: CO (4.77 - 11.73 %), H2 (13.48 - 25.45%), CO2 (11-25.2%), CH4 (0.43-1.73 %), and C2H6 (0.2- 0.69%). In general, the bed temperature profiles had peaks that ranged between 519 and 1032 degrees C for DB gasification.