Showing papers in "Biomass & Bioenergy in 1994"

Stability of wood fast pyrolysis oil

Abstract: This study evaluates the effects of storage conditions on physical and chemical properties of biomass fast pyrolysis oils exposed to elevated temperatures over extended periods of time. It was performed on oak pyrolysis oil generated in the NREL vortex reactor. Oil samples were stored at three temperatures: 37, 60 and 90°C in glass vessels. Properties of the oils were measured after hours of storage at 90°C, and after days or weeks at lower temperatures. Chemical changes in the oils were measured using GPC (molecular weight distribution) and FTIR spectroscopy. The oil remained a single phase throughout the studied conditions. Its pH was not affected by storage. The water content, viscosity and molecular weight of the oil increased with the time and temperature of storage. First-order reaction kinetics were successfully used to predict changes in molecular weight of the stored oil. FTIR provided evidence that etherification or esterification are mechanisms for condensation of the oil during storage.

Chemical elemental characteristics of biomass fuels

Abstract: A compilation of literature on chemical elemental characteristics of 280 samples of biomass fuels, including waste and peat, is presented The compositions of the compiled fuel samples were further classified by principal component analysis with special respect to elements important for ash and deposit formation From this analysis, a total of 15 biomass ‘reference fuels’ with similar compositions are presented, as well as the variances between them

A unified, global model for the pyrolysis of cellulose

Abstract: Complex interactions occur between the many competing and sequential chemical reactions during the pyrolysis of cellulose, making the prediction of the pyrolysis products relatively difficult. The purpose of this paper is to present cellulose pyrolysis as a comprehensible interaction of time, temperature and pressure. Appropriate kinetic data for seven first-order global reactions for the pyrolysis of cellulose were found in the literature. A mathematical model was developed, in which the seven reactions occurred simultaneously so long as the feedstock for the particular reaction existed. The seven differential equations representing the reaction rates were numerically integrated simultaneously to obtain the products of pyrolysis as a function of time, temperature, heating rate and pressure. This program was used to predict many results and trends observed in both slow and fast pyrolysis: very high yields of condensible vapors (primary oils) were predicted under high heating rates to modest final temperatures; high char yields were predicted for slow heating rates at low temperatures; high gas yields were predicted for fast pyrolysis at high temperatures.

Characterisation of oils from the fluidised bed pyrolysis of biomass with zeolite catalyst upgrading

Abstract: Biomass in the form of pine wood was pyrolysed in an externally heated 7.5 cm diameter, 100 cm high fluidised bed pyrolysis reactor with nitrogen as the fluidising gas. A section of the freeboard of the reactor was packed with zeolite ZSM-5 catalyst. The pyrolysis oils before and after catalysis were collected in a series of condensers and cold traps. In addition, gases were analysed off-line by packed column gas chromatography. The compositions of the oils and gases were determined in relation to the primary fluidised bed and after catalysis at increasing catalyst bed temperatures from 400° to 550°C. The oils were analysed by a number of techniques to determine composition, including liquid chromatography, gas chromatography/mass spectrometry. Fourier transform infrared spectroscopy and size exclusion chromatography. The results showed that the oils before catalysis were highly oxygenated; after catalysis the oils were markedly reduced in oxygenated species with an increase in aromatic and polycyclic aromatic species. The gases evolved from the fluidised bed pyrolysis of biomass were CO2, CO, H2, CH4, C2H4, C3H6 and minor concentrations of other hydrocarbon gases. After catalysis the concentrations of CO2 and CO were increased. The conversion of oxygenated compounds was mainly to H2O at lower catalyst temperatures and CO2 and CO at high catalyst temperatures. Detailed analysis of the oils showed that there were high concentrations of biologically active polycyclic aromatic species in the catalysed oil which increased with increasing catalyst temperature. The oxygenated compounds in the uncatalysed oil were mainly phenols and car☐ylic acids. After catalysis these decreased in concentration with increasing catalyst temperature

Biomass energy production in the United States: an overview

Abstract: This paper summarizes reports prepared for the U.S. Environmental Protection Agency (EPA) by researchers at the U.S. Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL). It also presents conclusions from a Biomass Energy Strategies Workshop conducted at ORNL. The Biofuels Feedstock Development Program (BFDP) has largely concentrated on the development of dedicated biomass feedstocks, referred to as energy crops. Two general types of energy crops have received the most attention—short-rotation woody crops (SRWC) and herbaceous energy crops (HEC). These cropping systems use traditional food production technologies as a means of maximizing the production of biomass per unit of land. Research focuses on the development of new crops and cropping technologies. The reports prepared for EPA and summarized by this article include discussions of crop production technologies, available land, economic considerations and environmental trade-offs. The discussion of other sources of biomass occurs only in the context of the workshop on biomass energy strategies. [The views expressed in this paper are those of the authors and do not necessarily represent the views of the U.S. Environmental Protection Agency or the U.S. Department of Energy.]

Upgrading of flash pyrolysis oil and utilization in refineries

Abstract: Flash pyrolysis oil from an ENSYN RTP pilot plant was upgraded in a continuous bench scale unit with commercial CoMo and NiMo catalysts in anticipation of scaling up the process. Large amounts of product were produced in a pilot plant for use in an extended analytical characterisation programme. In bench-scale experiments, high deoxygenation rates of 88–99.9% were achieved. Low liquid and high water yields were obtained. The fractionated products of the production run did not fulfil the requirements for direct use as gasoline and diesel. The process is restricted by several operational problems such as rapid catalyst deactivation, coking and plugging. Due to high feedstock and hydrogen addition costs, pyrolysis upgraded oil by the process tested is significantly more expensive than petroleum-derived oil at present oil prices.

Effects of energy forestry on soils

Abstract: The effects of energy forestry on former arable soils are summarized based on our own data from interdisciplinary field experiments as well as on literature published. The present results show that soil physical properties are influenced positively due to the lack of frequent input of heavy agricultural machinery. To what extent intensive harvesting effects may deteriorate soil structure and cause overcompactions with negative consequences for tree growth and ecological functions of soils, needs further attention. Soil solution nitrate can significantly be reduced in soils planted with fast growing trees, as long as nitrogen fertilizers are applied in accord with the nutrient demands of the trees. The ground vegetation may also act as an important nitrogen sink during plantation establishment and after harvesting. During the first phase after afforestation an enhanced mobilization of easily decomposable above ground and root litter residues takes place. Subsequently the carbon and nitrogen contents of afforrested soils increase in the long term mainly due to the lack of frequent soil cultivation. Among soil organisms, microbial biomass and most faunal groups, especially decomposers, are advanced under tree plantations. The diversity of soil fauna is generally increased compared to arable land. From the viewpoint of soil science general ecological criteria have to be considered in intensive forest land use systems. An entire and holistic view of the ecological consequences of energy forestry is necessary especially with respect to the long term, and to make forest biomass comparable and competitive with fossil fuels. There is a need for future research, which should include important chemical, physical and biological elements or processes in soils.

Numerical simulation of cellulose pyrolysis

Abstract: A mathematical model of transport phenomena and chemical processes of the thermal degradation of cellulose is presented. The kinetic model developed by Bradbury et al. (J. Appl. Polym. Sci.23, 3271, 1979) for primary pyrolysis is extended to include secondary reactions of volatiles: From the physical point of view, the model describes convective, conductive and radiative heat transfer, mass convection and diffusion and velocity and pressure variations interior to the porous solid (Darcy law). Furthermore, porosity, mass diffusivity, permeability and thermal conductivity vary with the composition of the reacting medium. Time and space evolution of the main variables, and reaction product distribution, are simulated by varying the reactor temperature and the reactor heating rate.

Anaerobic digestion of palm oil mill effluent using an up-flow anaerobic sludge blanket reactor

Abstract: Anaerobic treatment of palm oil mill effluent (POME) was studied using a 16-litre laboratory scale up-flow anaerobic sludge blanket reactor (UASB) run over a range of influent concentrations from 5.1 to 42.5 g Chemical Oxygen Demand (COD) per litre at a constant hydraulic retention time of four days. Methane production, volatile fatty acid conversion, net sludge growth and Chemical Oxygen Demand reduction were monitored. Over 96% Chemical Oxygen Demand was removed at loadings up to 10.6 g COD l −1 day −1 . At the highest influent concentration reactor instability was observed. Up to this point the results indicated that the UASB could treat POME more effectively than other systems reviewed.

Ablative plate pyrolysis of biomass for liquids

Abstract: Ablative pyrolysis is one of a range of fast or flash pyrolysis technologies for the production of liquids in high yields which offers the potential for high reactor specific throughputs with reduced equipment size, costs and improved controllability. The main objectives of the work are to design, construct and operate an ablative pyrolysis reactor and a pyrolysis liquids collection system which includes identification of key process parameters, exploration of relationships between parameters and product quality and the development of a new model to account for the ablative pyrolysis process. A reactor has been operated at temperatures from 450° to 600°C and at dry reacted wood feedrates up to 2.5 kg/h. Run times of 45 min have been achieved at steady state. Total liquid yields up to 81 wt% on dry ablatively pyrolysed wood basis have been achieved.

Structural studies on cellulose pyrolysis and cellulose chars by PYMS, PYGCMS, FTIR, NMR and by wet chemical techniques

Abstract: This paper summarizes observations and ideas on cellulose pyrolysis products and structural studies on cellulose chars with a focus on conceptual integration Information is presented on the larger gas phase oligosaccharides in cellulose pyrolysates, their mechanism of formation and the implications for the processes in the initial stages of char formation A model for the formation of a new thermally synthesized three-dimensional network polymer is proposed

Alkaline degradation of ALCELL® lignin

Abstract: ALCELL® lignin has been depolymerized by alkaline hydrolysis using a magnetically stirred batch autoclave. The effects of reaction temperature and time, combined into a single parameter (the reaction ordinate), were quantified in terms of the yields of unreacted lignin and identifiable liquid degradation products. At a high treatment severity, about 40% of the unreacted lignin is recovered as an alkaline-insoluble reactor residue, whilst at low to medium severities, this lignin is essentially all recovered by acid precipitation from the product mixture. The predominant identifiable liquid phenolic products ranged from guaiacol and syringol at low severities to catechol and its derivatives at high severities. Increasing concentrations of sodium hydroxide from 0 to 4% increased the conversion of lignin to liquid products from 7 to 30%. Based on the initial lignin, a maximum concentration of 4.4% identifiable phenols (mostly syringol = 2.4%), was found when using 0.5% NaOH, with a subsequent decrease with increasing alkali concentration. When a 50% ethanol-water mixture was used as the solvent, conversion remained essentially the same, but the methylene chloride solubles increased from 5 to 19%.

Environmental considerations in energy crop production

Abstract: Biomass energy has the potential to be a significant source of electric or liquid fuel energy in selected regions of the United States with valuable economic and environmental benefit to the country. By supplying biomass energy facilities with dedicated energy crops, fossil carbon emissions will be minimal or even negative due to carbon sequestration opportunities in the crops and soil. However, to maximize environment benefits, consideration must be taken of relative emissions to air and water, relative erosion rates, relative effects on long-term site productivity, and relative effects on habitat change and biodiversity. This paper is a preliminary attempt to provide information on the probable environmental effects of energy crop production relative to other potential uses of the land. While dedicated energy crop production is anticipated to occur primarily on land currently in agricultural production, some pastureland and forestland with a high potential for conversion to agricultural production may be utilized. Experimental results suggest that chemical use on energy crops will be lower than on most row crops and that land producing energy crops should experience less erosion than land producing row crops. Long-term site productivity should not be a major issue if macro- and microfertilizers are added as needed and nutrient-conserving production techniques are used. Biodiversity effects, as with most environmental issues, will depend greatly on how energy crop production is integrated into existing agricultural landscapes, how much land total becomes dedicated to energy crops, and what alternative uses for the land might exist.

Production technology status of woody and herbaceous crops

Abstract: Several woody and herbaceous energy crop species have been selected as high-potential candidates for supplying biomass feedstocks Successful methods for their establishment and maintenance have been developed Recommended species vary as a function of region of the country and soil type Yields are equally variable The crops that have received the most research and development include hybrid poplars (fast-growing trees) and switchgrass (a perennial grass) Some information is also available on other tree crops, thick-stemmed perennials and annuals Supplying large volumes of biomass to energy facilities on a daily basis requires that consideration be taken of the harvest timing, storage and delivery characteristics of different feedstocks as well as their yield, cost and energy properties Our summary suggests that a combination of crops will be needed to provide large amounts of low-cost and environmentally sustainable year-round supplies of biomass feedstocks

Water, alkali and char in flash pyrolysis oils

Abstract: Several biomass flash pyrolysis oils were analyzed to determine the forms of water, alkali and char in the oil. Representative oil samples were produced from oak, pine and switchgrass as representatives of hardwood, softwood and herbaceous biomass, respectively. Separations of the oil were undertaken to confirm the site of the alkali in the oil. Consideration was given to potential for char-encased alkali or alkali precipitation as char; alkali salts in water micro-droplets or alkali soap micelle formations; and organo-alkali component solution in the organic phase. Separations attempted included centrifugation, filtration, water dilutions and phase separations. Microscopic analysis of the oils was also attempted as well as scanning electron microscopic analysis of solids. A separate aqueous phase could not be found in the oil. Size distribution of char particulates showed a range primarily from 1 to 10 μ m. Inorganic components were concentrated in the char particles. Component analysis of the oils affirmed earlier analytical data found in the literature for flash pyrolysis oils.

Upgrading of a wood-derived oil over various catalysts

Abstract: The upgrading of a bio-oil using a fixed bed micro-reactor operating at 1 atm, 3.6 WHSV and 330–410°C over various catalysts is reported. The catalysts used were HZSM-5, silicalite, H-mordenite, H-Y and silica-alumina. The yield of hydrocarbons as well as the extent of deoxygenation, coke formation and conversion of the non-volatile portion of the bio-oil were used as measures of catalyst performance. The maximum hydrocarbon yield when HZSM-5 was used occurred at 370°C and was 39.3 wt% of the bio-oil. For the other catalysts, the hydrocarbon yields increased with temperature and were up to 22.1 wt% for silicalite; 27.5 wt% for H-mordenite; 21.0 wt% for H-Y; and 26.2 wt% for silica-alumina at 410°C. The hydrocarbon selectivity with HZSM-5 and silicalite catalysts was mostly for gasoline range hydrocarbons (C6 to C12) and for H-mordenite and H-Y for kerosene range hydrocarbons (C9 to C15). The hydrocarbon fraction obtained with silica-alumina did not produce any defined distribution. The pore size, catalyst acidity and catalyst shape selectively affected the product distribution. The overall performance followed the order: HZSM-5 > H-mordenite > H/Y > silica-alumina, silicalite.

Analysis of oil derived from liquefaction of Botryococcus Braunii

Abstract: Botryococcus braunii is a colonial green microalga that produces and accumulates oily hydrocarbons called botryococcenes (36% based on organics). It was reported that more oil was obtained than hydrocarbons in B. braunii when thermochemical liquefaction was applied to B. braunii for recovery of botryococcenes. In this paper, the properties of oil obtained by thermochemical liquefaction are clarified. The liquefied oil of B. braunii was fractionated into three fractions by silica gel column chromatography and analyzed to determine its composition. The yields of the three fractions based on organics were 5% of lower molecular weight hydrocarbons (MW, 197–281), 27.2% of botryococcenes (MW, 438–572) and 22.2% of polar substances (MW, 867–2209). The maximum recovery (78%) of botryococcenes in the liquefied oil was achieved at 200°C with the use of a catalyst.

Effect of light and temperature on the photosynthetic activity of the cyanobacterium Spirulina platensis

Abstract: The response of the photosynthetic activity of Spirulina platensis M2 to temperature and light stress was studied. The optimal temperature for photosynthesis was 35°C, while dark respiration was highest at 45 C. At temperature extremes outside those optimal for growth, both respiratory and photosynthetic activity declined. However, the sensitivity of respiration to such extremes was significantly greater than the sensitivity of photosynthesis under the same conditions. Under conditions where respiration was completely inhibited, photosynthetic oxygen evolution was maintained at about 30% of the optimum value. Exposing Spirulina cells to high photon flux densities results in a significant reduction in all the photosynthetic parameters (i.e. initial slope, light-saturated rate and the convexity of the photosynthesis-light response curve). The photoinhibitory stress resulted in much larger decreases in the quantum yield than in the light-saturated rate of photosynthetic oxygen evolution. The extent of photoinhibition was much higher when applied at temperatures over or below the optimum for photosynthesis. The implications of these findings are discussed with respect to the outdoor cultivation of Spirulina .

The economics of energy crop production

Abstract: This paper presents 1989 and 2010 cost estimates for growing and supplying biomass for five combinations of major cropping strategies and regions. Four of the dedicated feedstock supply systems (DFSS) use herbaceous energy crop (HEC) technologies, and one uses short-rotation woody crops (SRWC. The costs of producing systems for hybrid poplar, sorghum, switchgrass and energy cane are determined through the examination of such factors as cultivation systems, species, treatments, regions and site variability. The Midwest and South are the areas of focus, because they have the best potential for high yields and for contributing large quantities of land to the production of dedicated energy crops. At the assumed yields, sorghum in the Midwest and energy cane in the Southeast, appear to be the low-cost DFSS. Energy cane, susceptible to frost damage, is restricted to the Deep South. Sorghum should be restricted to cropland with low erosion potential. To be competitive with corn in the Midwest (not taking into account the benefits of government farm programs) and soybeans in the Southeast, dedicated energy crops must sell at between $43 and $60/dry Mg in 1989 and $30 and $43/dry Mg in 2010.

A review of some recent studies on mechanisms of pyrolysis of polysaccharides

Abstract: In seeking to gain a better understanding of the pyrolysis of polysaccharides, the pyrolytic behavior of a variety of naturally occurring and synthetic polysaccharides has been studied. Among the former were various glucans containing different linkage types, and for the latter, synthetic polymers were produced by thermal polymerization of a glucoside and of a xyloside. The study has focused on the effects which linkage types and inorganic additives have on pyrolytic pathways, with emphasis on the chemical mechanisms involved in the formation of one-, two- and three-carbon products, specifically glycolaldehyde, acetol, acetic acid, and formic acid. These compounds are the major non-aqueous components of the −60° condensate of the vacuum pyrolysate after removal of tar by room temperature condensation.13C labels in synthetic glucans were used to reveal the origins of these compounds. In general, the results show that each compound is formed by more than one mechanism. Specifically, glycolaldehyde derives mostly from C-1 and C-2 of the glucose monomers, with C-5 and C-6 also contributing significantly. Acetol and acetic acid derive mostly from contiguous carbons that include a terminal carbon (C-1 or C-6), most often C-6, appearing as the methyl carbon. About half of the formic acid arises from C-1. Some mechanisms derived from solution chemistry are proposed.

Biological pest control

Abstract: For the purposes of energy forests, we argue that biological pest control should be interpreted as any method of using natural organisms or their products for the regulation of herbivores, below the economic threshold. The organisms include the energy forest crop species and natural enemies of pest herbivores. In natural vegetation, potentially harmful arthropod herbivores are normally regulated at low populations through a combination of bottom-up forces in food webs including edaphic factors and plant factors, and top-down effects from carnivores. Bottom-up effects tend to be strong, impacting both herbivores and carnivores in the food web, forcing the consideration of three-trophic-level systems as the minimal unit of study. Examples are provided of three-trophic-level interactions, including some on willows and poplars. Bottom-up effects may be particularly strong in juvenile Salicaceae, which are used in energy forest production, because plants are growing vigorously, and many herbivores respond positively. Some major pests on willows and poplars appear to have weak top-down regulation, and they may be influenced most by bottom-up effects such as plant resistance through genetic variation, ontogenetic aging and physiological aging. Balancing the bottom-up and top-down forces in energy forests may be difficult in short-rotation crops, but harvesting may prove to be important as a control during pest outbreaks damaging to yield. However, we suggest that many aspects of energy forests are conducive to pest control, which are enumerated, and emphasize the need for further research on native three-trophic-level systems, economic thresholds, cultural methods and crop species and genotype selection.

Nutrient cycling in energy forest plantations

Abstract: Knowledge about growth and nutrient uptake dynamics within and between seasons, internal nutrient cycling, decomposition and mineralization of litter as well as nutrient losses due to harvest and leakage in energy forest plantations are reviewed. These topics, especially in connection to willow plantations, will be presented and discussed, and where possible, comparisons with other fast growing deciduous tree species like grey alder and poplar will be made. A nitrogen budget during the two first rotations of a willow plantation on good agricultural soil is presented. It is concluded that the fertilizer need in well established and high yielding (⪢12 tonnes stems, dry weight, ha −1 year −1 ) stands is small, about 30 kg N ha −1 yr −1 , due to an efficient recycling of N from litter and the relatively low nutrient content in the harvested biomass (stems).

An analysis of the potential land base for energy crops in the conterminous United States

Abstract: An analysis of the potential land base for energy crops in the conterminous United States has identified 158.6 million ha that can grow short-rotation woody crops (SRWC) and herbaceous energy crops (HEC) without irrigation. Of this land, 145.3 million ha is currently used for agriculture as either cropland or pastureland, but agricultural land needs are anticipated to decline in the future. Both SRWC and HEC may be suitable crops for surplus cropland. Of the capable land base, 91.1 million ha is suitable for SRWC, and 131.1 million ha is suitable for HEC. Suitability is based on an assumption that the land must be capable of energy crop yields of at least 11.2 Mg ha −1 yr−1 with current technology. Most of this suitable land is in the North Central, South Central and Southeastern regions of the United States, although present predictions suggest that future cropland surpluses will occur largely in the Great Plains and Mountain regions of the United States. This paper defines the land suitable for energy crop production and estimates the yield potential of that land. Analyses of the relative economics of energy crop and alternative agricultural land uses will be required before the land base potentially available for energy crop production can be defined.

Trees and biomass energy: Carbon storage and/or fossil fuel substitution?

Abstract: Studies on climate change and energy production increasingly recognise the crucial role of biological systems. Carbon sinks in forests (above and below ground), C02 emissions from deforestation, planting trees for carbon storage, and biomass as a substitute for fossil fuels are some of the key issues which arise. This paper assesses various forestry strategies and examines land availability, forest management, environmental sustainability, social and political factors, infrastructure and organisation, economic feasibility, and ancillary benefits associated with biomass for energy. Halting deforestation is of paramount importance and should have priority above all other options, although it will not be easy to implement for a variety of well known reasons. There is also great potential for reforestation of degraded lands, agroforestry and improved forest management. We conclude biomass energy plantations and other types of energy cropping could be a more effective strategy for carbon mitigation than simply growing trees as a carbon store, particularly on higher productivity lands. Use of the biomass produced as an energy source has the added advantage of a wide range of other environmental, social and economic benefits. The constraints to achieving environmentally-acceptable biomass production are not insurmountable. Rather they should be seen as scientific and entrepreneurial opportunities which will yield numerous advantages in the long term.

Physical properties of flash pyrolysis liquids

Abstract: Process design requires knowledge of the physical and chemical properties of the fluids being handled The measurement of a range of properties of two pyrolysis liquids is described The pyrolysis liquid properties reported are: density, viscosity, refractive index, thermal capacity, thermal conductivity, and their variation with temperature, time, exposure to air/oxygen and history The oils follow conventional behaviour for most properties except that there is marked differences in viscosity behaviour above around 50°C compared to below 50°C There is a noticeable effect from exposure to oxygen/air which increases viscosity This may be due to removal of volatiles, removal of water or reaction There is clear evidence that some reaction occurs even under ambient conditions

Techno-economic modelling of biomass flash pyrolysis and upgrading systems

Abstract: The thermochemical conversion of biomass by flash pyrolysis or liquefaction produces a crude liquid that can be used directly to substitute for conventional fossil fuels or upgraded to a higher quality fuel. Both the crude and upgraded products may be utilised for power generation. A computer program is used to model the flash pyrolysis of biomass with subsequent upgrading and refining of the crude liquid products to produce higher value and more marketable liquid fuel products. The structure and scope of the program, the hydrotreating model and the development of an energy self-sufficient flash pyrolysis model are detailed. The program is used to assess and compare the economic and technical opportunities for upgrading crude pyrolysis liquids into the higher quality fuels demanded by more advanced technologies.

Hydrocracking of organocell lignin for phenol production

Abstract: Organocell lignin has been subjected to catalytic hydrocracking in a semicontinuous reactor system using four petroleum-derived slurry oils and a lignin-derived one. The objective was to maximize the yield of phenols which can be further converted to methylarylethers for the use as gasoline octane number improvement. Experiments were carried out by varying temperature (375°–450°C), hydrogen pressure (75–180 bar), and catalyst (sulfided NiMo, zeolite A, and none). The most complete conversion (coke formation only 0.3%) was obtained at 375°C and 180 bar when lignin was mixed with a lignin-derived slurry oil. The formation of phenols was monitored by quantitative capillary gas chromatography. Up to 12.8wt% (based on lignin) of a mixture of mono-phenols was obtained. The yields of single products (in wt% based on lignin) are as follows: phenol 2.3, cresols 5.0, xylenols 4.2, guaiacol 1.3.

Measurement and modeling of lignin pyrolysis

Abstract: Pyrolysis of lignin is one approach that has been investigated to upgrade this material into higher value products. However, there have been relatively few efforts to quantitatively model these reactions. This paper describes a methodology for modeling lignin pyrolysis which has been extensively developed for related materials like coal. The samples are characterized using pyrolysis experiments under a standard set of conditions, where the products are analyzed by Fourier Transform Infrared (FT-IR) Spectroscopy and Field Ionization Mass Spectrometry (FIMS). Solvent extraction experiments are done to determine the extractables yields and elemental analysis is done to further constrain the model. One lignin, produced from ethanol/water extraction of mixed hardwoods, was selected for the application of this modeling approach. The model was able to qualitatively predict the tar molecular weight distributions and quantitatively predict the variations of the gas and tar evolution rates and yields with heating rate for the calibration set of experiments. The model can be improved by more precise information on lignin structure, crosslinking chemistry, and tar transport mechanisms. It also needs to be validated by simulation of pyrolysis conditions at high heating rates and/or high pressures for which data is currently not available.

Use of pyrolysis oil in a test diesel engine to study the feasibility of a diesel power plant concept

Abstract: The economic viability of power production in a diesel power plant utilizing flash pyrolysis oil produced from sawmill wastes in Finland has been investigated. A combination of biomass feedstock costs, pyrolysis oil fuel properties (ignition quality, lubricating properties, combustion speed and duration, emissions, etc.) and their effect on power plant investments and maintenance will ultimately determine electricity busbar costs and the economic competitiveness of the concept. Pyrolysis oil is not a suitable fuel for a conventional diesel engine as such. The preliminary tests with additive treated pyrolysis oil demonstrated, however, that once ignition has taken place, pyrolysis oil burns rapidly. Pyrolysis oil may be a suitable primary fuel for a diesel engine with a pilot injection system, which secures the ignition of the main fuel.

Technoeconomic analysis of the production of biocrude from wood

Abstract: The production of biomass-derived oil (biocrude) has been studied to determine the technoeconomic characteristics of the process. A detailed process model was developed for the production of biocrude from wood chips. The process consists of a silo dryer for the removal of water from the feed wood, a vortex reactor for the pyrolysis of the wood, a furnace to provide the required sensible heat and heat of reaction for the pyrolysis reaction, a steam turbine to convert excess thermal energy into electric power, and a biocrude recovery section. Results of the simulation were used to size and cost major equipment items. Technoeconomic evaluation of the process was conducted to develop an understanding of the important parameters and to identify missing or incomplete data. Studies were conducted to illustrate the importance of economic parameters on the perceived viability of a process. Plant size and production capacity were examined, as were a number of process development strategies.