Flax shives are a source of abundant biomass from renewable sources. They are considered to be environmentally benign and have a high-energy content for heating and generation of electricity, but only after being processed into pellets. Pelleting of the shives was done by using the single-pelleter and pilot-scale mill. The effect of grinding with screens of 2.4, 3.2, and 6.4 mm on unit density and durability was conducted with a completely randomized design using shives from Biofibre Industries Inc., Canora, SK. The central composite face-centered design with 3 levels of lower grade canola meal used as a binder (18, 21, and 24%), moisture content (8, 11, and 14% (w.b)), and hammer mill screen size (3.2, 4.8, and 6.4 mm) was used to determine the effects of these three factors on the properties of fuel pellets made from shives obtained from Biolin Research Inc., Saskatoon, SK. The initial moisture content of coarse flax shives from both sources was about 10.5% wet basis (w.b.). The moisture content of flax shive grinds ranged from 9.6 to 10.5% (w.b.) after grinding, using the smaller screens for the Biofibre material, while the moisture content ranged from 7.9 to 8.6% (w.b.) for shives from Biolin. Also, smaller screen size reduced the geometric mean particle size for shives from both sources. The use of the smaller hammer mill screen resulted in an increase in both bulk and particle density of shives. There was a decrease in coefficient of the internal friction of shives from 0.20 to 0.14 and an increase in a cohesion of shives from 2.18 to 3.83 kPa when the screen size decreased from 6.4 to 3.2 mm. The flax shives contained cellulose (53.27%), hemicelluloses (13.62%), and lignin (20.53%) at a moisture content of 7.9% (w.b). Specific heat capacity of flax shives changed from 1.5 to 2.7 kJ/ (kg °C) when the moisture content was increased from 8 to14% (w.b.) and temperature from 15 to 80°C. The shives had the combustion energy of 17.67 MJ/kg at a moisture content of 8.1% (w.b.).<p> The smallest screen size (2.4 mm) resulted in the highest unit density (1010 kg/m3) and the highest durability (88%) in the pellets produced by the single-pelleting equipment. The change in length of pellets produced by the pilot-scale mill increased as canola meal increased from 18 to 24% at the highest moisture content (%). The pellets were more stable at the highest moisture content when the lowest canola meal used. The addition of 18% canola meal and grinds from a screen size of 6.4 mm produced the highest unit density in the pellets at all moisture levels. The highest bulk density (682 kg/m3) was obtained from shive mixtures with 18% canola meal and a moisture content of 8%. The highest hardness and durability were found for the shive pellets that were produced with 18% canola meal at a moisture content of 14% (w.b). Pellets that were produced at a moisture content of 14% (w.b) resulted in the lowest percentage of moisture absorption. The inclusion of the canola meal in the shive mixture resulted in an increase in the combustion energy of the pellets because of the fat content in the binder. The two levels of canola meal for shive pellets had essentially the same level of emissions. However, there were significant differences between shive pellets and commercial wood pellets in the level of the emissions. Lower amounts of methane (1.29 ppm) and oxygen (164.3 ppt) were found for flax shive pellets than of methane (1.63 ppm) and oxygen (176.6 ppt) in commercial wood pellets.<p> In short, pelleting of flax shives into fuel pellets improved the handling characteristics, increased bulk density and energy content. Fuel pellets made from flax shives had less emission of methane and oxygen from combustion when compared to commercial wood pellets.

Experimental and kinetic modeling studies were carried out on the conversion a wood-oil obtained from high pressure liquefaction of aspen poplar wood to liquid hydrocarbon fuels and useful chemicals in a fixed bed micro-reactor using HZSM-5 catalyst. Similar experiments were conducted using silicalite, H-mordenite, H-Y and amorphous silica-alumina catalysts. <p> Preliminary vacuum distillation studies showed that the wood-oil was made up of volatile and non-volatile fractions. A maximum yield of 62 wt% volatiles at 200 °C, 172 Pa was obtained. The volatile fraction consisted of over 80 compounds. These compounds were comprised of acids, alcohols, aldehydes, ketones, esters, ethers, furans, phenols and some hydrocarbons. The characteristics of the oil showed that it was unstable with time, i.e., its physical properties and chemical composition changed with time probably due to the reaction of free radicals or the oxidative coupling of some of the wood-oil components. However, when the oil was mixed with tetralin, the stability improved. <p> Upgrading studies were first conducted over inert berl saddles in the presence and absence of steam (i. e. non-catalytic treatment/blank runs). Yields of hydrocarbons were between 16 and 25 wt% of the wood-oil. High residue fractions of between 32 to 56 wt% were obtained after processing. Some portions of wood-oil formed a carbonaceous material (char or coke) when exposed to the experimental temperatures. The chars (coke) fraction increased with temperature from 4.7 to 12.5 wt% when processing with steam and 8.0 to 20.4 wt% when processing without steam. <p> Catalytic upgrading studies were first carried out using HZSM-5 catalyst in the presence and absence of steam. The results showed that approximately 40 to 65 wt% of the oil could be converted to a hydrocarbon-rich product (i.e. desired organic liquid product (distillate). This contained about 45 to 70 wt% hydrocarbons with selectivities ranging between 0.47 to 0.88. This fraction was highly aromatic in nature and consisted mainly of benzene, toluene, xylene (BTX compounds) and other alkylated benzenes within the gasoline boiling point range. The yield and selectivities were strong functions of the process time and temperature. A comparison between the two processes, i.e. upgrading in the presence and absence of steam, showed that about 30 to 45 % reduction in coke formation and 5 to 18 wt% increase in organic distillate could be achieved when processing in the presence of steam. These changes were probably due to changes in the rates of cracking, deoxygenation, aromatization and polymerization reactions resulting from the competitive adsorption processes between steam and wood-oil molecules in addition to changes in contact time of molecules. However, the selectivity for hyqrocarbons decreased in the presence of steam. <p> Yields of organic distillate fractions of between 72 to 93 wt% and hydrocarbon yields and selectivities of 44 to 51 wt% and 0.93 to 1.13, respectively, were obtained when wood-oil volatile fraction was upgraded over HZSM-5 after separation from the non-volatile fraction by vacuum distillation. <p> The spent HZSM-5 catalyst could be easily regenerated and reused with little change in its performance. <p> The yields and selectivities for hydrocarbons when upgrading with the other catalysts were between 9 and 22 wt%, and 0.12 and 0.29, respectively for silicalite, 16 and 28 wt%, and 0.22 and 0.28, respectively for H-mordenite, 15.5 and 21 wt%, and 0.17 and 0.21, respectively for H-Y and S.5 and 26.2, and 0.13 and 0.36, resrectively for silica-alumina. Compared to HZSM-5 (yield between 34 and 43 wt%, selectivity of 0.66 to O.SS) these yields and selectivities were much lower. These experiments also showed that the pore size, acidity and shape selectivity of the catalyst influenced the distribution of hydrocarbons in terms of the carbon number. The yield and selectivity of H-mordenite and H-Y (large pore zeolites) were mostly for kerosene range hydrocarbons (C_{<font size=2>9</font>} to C_{<font size=2>15</font>}) and for silicalite and HZSM-5 (medium pore zeolites) for gasoline range hydrocarbons. The hydrocarbon fraction from amorphous silica-alumina did not show any defined distribution. The performance followed the order: HZSM-5> H-mordenite> H-Y> Silicalite, Silica-alumina.<p> With the aid of model compound reactions involving acetic acid methyl ester, propanoic acid, 4-methylcyclohexanol, methylcyclopentanone, 2-methylcyclopentanone, methoxybenzene, ethoxybenzene, phenol, 2-methoxy-4-(2-propenyl) phenol, a synthetic and wood-oil volatile, two reaction pathways were proposed to explain the chemical steps through which the final products of upgrading were obtained. Also, reaction pathways were proposed for each chemical group. These experiments showed that the final products were formed probably through cracking, deoxygenation, olefin formation, oligomerization, hydrogen and hydride transfer, cyclization, isomerization, alkylation and polymerization reactions. <p> Rate models were derived based upon the two reaction pathways and the power law rate model. The rates of formation of products followed the general order: Organic distillate> Hydrocarbons> Residue> Coke> Gas >Aqueous Fraction. Estimates of the values of the kinetic parameters showed that the rate constants ranged between 10^{<font size=2>-6</font>} (aqueous fraction) and 1.81 (volatile fraction), activation energies between 6.7-76.0 x 10^{<font size=2> 3</font>} KJ/Kmol and reaction orders from 0.7 (gas formation) to 2.5 (residue formation). Two mathematical models were derived based on the integral reactor design equation and on the two reaction pathways. This was used to estimate the yield of products. The models predicted the experimental results fairly accurately. Model discrimination showed that the model based on coke and residue formation from both volatile and non­-volatile fractions of the wood-oil best predicted the experimental results.<p> Hydrocarbon selectivity relations which were based on coke, residue and combined coke and residue as undesired products were also derived. Application of these relations showed that lower temperatures and concentrations were most appropriate for higher hydrocarbon selectivity. However, this was at the expense of higher conversions.

Flax shives are a source of abundant biomass from renewable sources. They are considered to be environmentally benign and have a high-energy content for heating and generation of electricity, but only after being processed into pellets. Pelleting of the shives was done by using the single-pelleter and pilot-scale mill. The effect of grinding with screens of 2.4, 3.2, and 6.4 mm on unit density and durability was conducted with a completely randomized design using shives from Biofibre Industries Inc., Canora, SK. The central composite face-centered design with 3 levels of lower grade canola meal used as a binder (18, 21, and 24%), moisture content (8, 11, and 14% (w.b)), and hammer mill screen size (3.2, 4.8, and 6.4 mm) was used to determine the effects of these three factors on the properties of fuel pellets made from shives obtained from Biolin Research Inc., Saskatoon, SK. The initial moisture content of coarse flax shives from both sources was about 10.5% wet basis (w.b.). The moisture content of flax shive grinds ranged from 9.6 to 10.5% (w.b.) after grinding, using the smaller screens for the Biofibre material, while the moisture content ranged from 7.9 to 8.6% (w.b.) for shives from Biolin. Also, smaller screen size reduced the geometric mean particle size for shives from both sources. The use of the smaller hammer mill screen resulted in an increase in both bulk and particle density of shives. There was a decrease in coefficient of the internal friction of shives from 0.20 to 0.14 and an increase in a cohesion of shives from 2.18 to 3.83 kPa when the screen size decreased from 6.4 to 3.2 mm. The flax shives contained cellulose (53.27%), hemicelluloses (13.62%), and lignin (20.53%) at a moisture content of 7.9% (w.b). Specific heat capacity of flax shives changed from 1.5 to 2.7 kJ/ (kg °C) when the moisture content was increased from 8 to14% (w.b.) and temperature from 15 to 80°C. The shives had the combustion energy of 17.67 MJ/kg at a moisture content of 8.1% (w.b.).<p> The smallest screen size (2.4 mm) resulted in the highest unit density (1010 kg/m3) and the highest durability (88%) in the pellets produced by the single-pelleting equipment. The change in length of pellets produced by the pilot-scale mill increased as canola meal increased from 18 to 24% at the highest moisture content (%). The pellets were more stable at the highest moisture content when the lowest canola meal used. The addition of 18% canola meal and grinds from a screen size of 6.4 mm produced the highest unit density in the pellets at all moisture levels. The highest bulk density (682 kg/m3) was obtained from shive mixtures with 18% canola meal and a moisture content of 8%. The highest hardness and durability were found for the shive pellets that were produced with 18% canola meal at a moisture content of 14% (w.b). Pellets that were produced at a moisture content of 14% (w.b) resulted in the lowest percentage of moisture absorption. The inclusion of the canola meal in the shive mixture resulted in an increase in the combustion energy of the pellets because of the fat content in the binder. The two levels of canola meal for shive pellets had essentially the same level of emissions. However, there were significant differences between shive pellets and commercial wood pellets in the level of the emissions. Lower amounts of methane (1.29 ppm) and oxygen (164.3 ppt) were found for flax shive pellets than of methane (1.63 ppm) and oxygen (176.6 ppt) in commercial wood pellets.<p> In short, pelleting of flax shives into fuel pellets improved the handling characteristics, increased bulk density and energy content. Fuel pellets made from flax shives had less emission of methane and oxygen from combustion when compared to commercial wood pellets.

The low NOx burner (LNB) is the most cost effective technology used in coal-fired power plants to reduce NOx. Conventional (unstaged) burners use primary air for transporting particles and swirling secondary air to create recirculation of hot gases. LNB uses staged air (dividing total air into primary, secondary and tertiary air) to control fuel bound nitrogen from mixing early and oxidizing to NOx; it can also limit thermal NOx by reducing peak flame temperatures. Previous research at Texas A&M University (TAMU) demonstrated that cofiring coal with feedlot biomass (FB) in conventional burners produced lower or similar levels of NOx but increased CO. The present research deals with i) construction of a small scale 29.31 kW (100,000 BTU/hr) LNB facility, ii) evaluation of firing Wyoming (WYO) coal as the base case coal and cofiring WYO and dairy biomass (DB) blends, and iii) evaluating the effects of staging on NOx and CO. Ultimate and Proximate analysis revealed that WYO and low ash, partially composted, dairy biomass (LA-PC-DB-SepS) had the following heat values and empirical formulas: CH0.6992N0.0122O0.1822S0.00217 and CH_1.2554N_0.0470O_0.3965S_0.00457. The WYO contained 3.10 kg of Ash/GJ, 15.66 kg of VM/GJ, 0.36 kg of N/GJ, and 6.21 kg of O/GJ while LA-PC-DB-SepS contained 11.57 kg of Ash/GJ, 36.50 kg of VM/GJ, 1.50 kg of N/GJ, and 14.48 kg of O/GJ. The construction of a LNB nozzle capable of providing primary, swirled secondary and swirled tertiary air for staging was completed. The reactor provides a maximum residence time of 1.8 seconds under hot flow conditions. WYO and DB were blended on a mass basis for the following blends: 95:5, 90:10, 85:15, and 80:20. Results from firing pure WYO showed that air staging caused a slight decrease of NOx in lean regions (equivalence ratio, greater than or equal to 1.0) but an increase of CO in rich regions (=1.2). For unstaged combustion, cofiring resulted in most fuel blends showing similar NOx emissions to WYO. Staged cofiring resulted in a 12% NOx increase in rich regions while producing similar to slightly lower amounts of NOx in lean regions. One conclusion is that there exists a strong inverse relationship between NOx and CO emissions.

Gasification is a thermo-chemical process which transforms biomass into valuable synthesis gas. Integrated with a biorefinery it can address the facility’s residue handling challenges and input demands. A number of feedstock, technology, oxidizer and product options are available for gasification along with combinations thereof. The objective of this work is to create a systematic method for optimizing the design of a residual biomass gasification unit. In detail, this work involves development of an optimization superstructure, creation of a biorefining scenario, process simulation, equipment sizing & costing, economic evaluation and optimization. The superstructure accommodates different feedstocks, reactor technologies, syngas cleaning options and final processing options. The criterion for optimization is annual worth. A biorefining scenario for the production of renewable diesel fuel from seed oil is developed; gasification receives the residues from this biorefinery. Availability of Soybeans, Jatropha, Chinese Tallow and woody biomass material is set by land use within a 50-mile radius. Four reactor technologies are considered, based on oxidizer type and operating pressure, along with three syngas cleaning methods and five processing options. Results show that residual gasification is profitable for large-scale biorefineries with the proper configuration. Low-pressure air gasification with filters, water-gas shift and hydrogen separation is the most advantageous combination of technology and product with an annual worth of $9.1 MM and a return on investment of 10.7 percent. Low-pressure air gasification with filters and methanol synthesis is the second most advantageous combination with an annual worth of $9.0 MM. Gasification is more economic for residue processing than combustion or disposal, and it competes well with natural gas-based methanol synthesis. However, it is less economic than steam-methane reforming of natural gas to hydrogen. Carbon dioxide credits contribute to profitability, affecting some configurations more than others. A carbon dioxide credit of $33/t makes the process competitive with conventional oil and gas development. Sensitivity analysis demonstrates a 10 percent change in hydrogen or electricity price results in a change to the optimal configuration of the unit. Accurate assessment of future commodity prices is critical to maximizing profitability.

Oxides of nitrogen from coal-fired power stations are considered to be major pollutants, and there is increasing concern for regulating air quality and offsetting the emissions generated from the use of energy. Reburning is an in-furnace, combustion control technology for NOx reduction. Another environmental issue that needs to be addressed is the rapidly growing feedlot industry in the United States. The production of biomass from one or more animal species is in excess of what can safely be applied to farmland in accordance with nutrient management plans and stockpiled waste poses economic and environmental liabilities. In the present study, the feasibility of using biomass as a reburn fuel in existing coal-fired power plants is considered. It is expected to utilize biomass as a low-cost, substitute fuel and an agent to control emission. The successful development of this technology will create environment-friendly, low cost fuel source for the power industry, provide means for an alternate method of disposal of biomass, and generate a possible revenue source for feedlot operators. In the present study, the effect of coal, cattle manure or feedlot biomass, and blends of biomass with coal on the ability to reduce NOx were investigated in the Texas A&M University 29.31 kW (100,000 Btu/h) reburning facility. The facility used a mixture of propane and ammonia to generate the 600 ppm NOx in the primary zone. The reburn fuel was injected using air. The stoichiometry tested were 1.00 to 1.20 in the reburn zone. Two types of injectors, circular jet and fan spray injectors, which produce different types of mixing within the reburn zone, were studied to find their effect on NOx emissions reduction. The flat spray injector performed better in all cases. With the injection of biomass as reburn fuel with circular jet injector the maximum NOx reduction was 29.9 % and with flat spray injector was 62.2 %. The mixing time was estimated in model set up as 936 and 407 ms. The maximum NOx reduction observed with coal was 14.4 % and with biomass it was 62.2 % and the reduction with blends lay between that of coal and biomass.

Lignocellulose is a promising and valuable alternative energy source. Native lignocellulosic biomass has limited accessibility to cellulase enzyme due to structural features; therefore, pretreatment is an essential prerequisite to make biomass accessible and reactive by altering its structural features. The effects of substrate concentration, addition of cellobiase, enzyme loading, and structural features on biomass digestibility were explored. The addition of supplemental cellobiase to the enzyme complex greatly increased the initial rate and ultimate extent of biomass hydrolysis by converting the strong inhibitor, cellobiose, to glucose. A low substrate concentration (10 g/L) was employed to prevent end-product inhibition by cellobiose and glucose. The rate and extent of biomass hydrolysis significantly depend on enzyme loading and structural features resulting from pretreatment, thus the hydrolysis and pretreatment processes are intimately coupled because of structural features. Model lignocelluloses with various structural features were hydrolyzed with a variety of cellulase loadings for 1, 6, and 72 h. Glucan, xylan, and total sugar conversions at 1, 6, and 72 h were linearly proportional to the logarithm of cellulase loadings from approximately 10% to 90% conversion, indicating that the simplified HCH-1 model is valid for predicting lignocellulose digestibility. Carbohydrate conversions at a given time versus the natural logarithm of cellulase loadings were plotted to obtain the slopes and intercepts which were correlated to structural features (lignin content, acetyl content, cellulose crystallinity, and carbohydrate content) by both parametric and nonparametric regression models. The predictive ability of the models was evaluated by a variety of biomass (corn stover, bagasse, and rice straw) treated with lime, dilute acid, ammonia fiber explosion (AFEX), and aqueous ammonia. The measured slopes, intercepts, and carbohydrate conversions at 1, 6, and 72 h were compared to the values predicted by the parametric and nonparametric models. The smaller mean square error (MSE) in the parametric models indicates more satisfactorily predictive ability than the nonparametric models. The agreement between the measured and predicted values shows that lignin content, acetyl content, and cellulose crystallinity are key factors that determine biomass digestibility, and that biomass digestibility can be predicted over a wide range of cellulase loadings using the simplified HCH-1 model.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Christopher Jones; Committee Co-Chair: Dr. Pradeep Agrawal; Committee Member: Dr. Sujit Banerjee; Committee Member: Dr. Tom Fuller. Part of the SMARTech Electronic Thesis and Dissertation Collection.

There is growing need for technologies to displace traditional petroleum resources. Towards this goal, lignocellulosic biomass is seen as a potential renewable resource for the production of fuels and commodity chemicals. One of the most difficult components of lignocellulose to process is lignin, which is a complex, amorphous aromatic polymer that acts as one of the structural components in plants. Ionic liquids are a class of compounds that are composed completely of anions and cations that, in some cases, can completely dissolve lignocellulosic biomass. The research performed for this dissertation aims to advance the technologies of lignocellulose processing through effective depolymerization of lignin in ionic liquids. Lignin fragments from this depolymerization could be used as a feedstock for further processing into aromatic commodity chemicals or polymers. Additionally, by removing lignin, biomass becomes much more accessible to enzymatic or chemical saccharification as a step towards fermentation into ethanol or other fuels. Both base and acid catalyzed methods were explored, although the base promoted depolymerization of lignin in ionic liquids did not show much promise, as the reaction was never shown to be catalytic. Acidic routes towards lignin depolymerization were more successful. Using the acidic ionic liquid 1-H-3-methylimiazolium chloride, the ether linkages in lignin model compounds could be hydrolyzed with high yields. This technology was also applicable to the whole lignin macromolecule. The mechanisms of this reaction, as well as the effects on lignin were explored with various neutral and acidic ionic liquids, using HPLC, GPC, NMR, FT-IR, and mass spectrometry for analysis of samples. To demonstrate the applications of this technique, pine wood was treated with the acidic ionic liquids to open the structure of the wood to enzymatic saccharification through the removal of lignin and hemicellulose. / text

SAR backscatter data contain both geometric and radiometric distortions due to underlying topography and the radar viewing geometry. Thus, applications using SAR backscatter data for deriving various scientific products (e.g. above ground biomass) require accurate absolute radiometric calibration. The calibration process involves estimation of the local radar scattering area through knowledge of the imaged terrain, which is often obtained through DEMs. High resolution UAVSAR data over a New Hampshire boreal forest test site was radiometrically calibrated using a low resolution SRTM DEM, and different calibration methods were tested and compared. Heteromorphic methods utilizing DEM integration are able to model scattering area better than homomorphic methods based on the local incidence or projection angle with a resultant backscatter calibration difference of less than 0.5 dB. Additionally, the impact of low DEM resolution on the calibration was investigated through a Fourier analysis of different topographic classes. Power spectra of high-resolution airborne lidar DEMs were used to characterize the topography of steep, moderate, and flat terrain. Thus, errors for a given low resolution DEM associated with a particular topographic class could be quantified through a comparison of its power spectrum with that from the lidar. These errors were validated by comparing DEM slope derived from SRTM and lidar DEMs. The impact of radiometric calibration on the biomass retrieval capabilities of UAVSAR data was investigated by fitting second-order polynomials to backscatter vs. biomass plots for the HH, HV, and VV polarizations. LVIS RH50 values were used to calculate biomass, and the process was repeated for both uncalibrated and area calibrated UAVSAR images. The calibration improved the $R^2$ values for the polynomial fits by 0.7-0.8 for all three polarizations but had little effect on the polynomial coefficients. The Fourier method for predicting DEM errors was used to predict biomass errors due to the calibration. It was revealed that the greatest errors occurred in the near range of the SAR image and on slopes facing towards the radar. / text