Lignocellulosic biomass pyrolysis mechanism: A state-of-the-art review

PROMETHEE: A comprehensive literature review on methodologies and applications

https://pubs.rsc.org/en/Content/ArticlePDF/2013/GC/C2GC36364J

Deconstruction of lignocellulosic biomass with ionic liquids

The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and
future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately
30% of the country’s present petroleum consumption. To ensure reasonable confidence in the study results, an effort was made to use relatively conservative assumptions. However, for both agriculture and forestry, the resource potential was not restricted by price. That is, all identified biomass was potentially available, even though some potential feedstock would more than likely be too expensive to actually be economically available.
In addition to updating the 2005 study, this report attempts to address a number of its shortcomings

/pdf/u-s-billion-ton-update-biomass-supply-for-a-bioenergy-and-39t7zcevg2.pdf

U.S. Billion-ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry

Furfural offers a promising, rich platform for lignocellulosic biofuels. These include methylfuran and methyltetrahydrofuran, valerate esters, ethylfurfuryl and ethyltetrahydrofurfuryl ethers as well as various C(10)-C(15) coupling products. The various production routes are critically reviewed, and the needs for improvements are identified. Their relative industrial potential is analysed by defining an investment index and CO(2) emissions as well as determining the fuel properties for the resulting products. Finally, the most promising candidate, 2-methylfuran, was subjected to a road trial of 90,000 km in a gasoline blend. Importantly, the potential of the furfural platform relies heavily on the cost-competitive production of furfural from lignocellulosic feedstock. Conventional standalone and emerging coproduct processes-for example, as a coproduct of cellulosic ethanol, levulinic acid or hydroxymethyl furfural-are expensive and energetically demanding. Challenges and areas that need improvement are highlighted. In addition to providing a critical review of the literature, this paper also presents new results and analysis in this area.

Furfural—A Promising Platform for Lignocellulosic Biofuels

Corn stover is a currently low-value product that has been suggested as an ideal pioneer cellulosic feedstock for
conversion to chemicals and fuel because of its abundance and proximity to existing grain-to-ethanol conversion facilities.
However, corn stover is high in moisture at the time of grain harvest. High-moisture corn stover is difficult to handle, spoils
readily, is prone to spontaneous combustion, and is a safety hazard when moldy; thus, field drying becomes an important
consideration. Data on field moisture content, quantity, and quality of the corn plant fractions are essential to the on-going
analysis of the stover supply system. This study involved monitoring the in-field dry down and biomass yield in two corn
hybrids, Pioneer 32K61 and 32K64 (Bt), grown under southeastern U.S. conditions. The standing corn was sampled over a
109-day period that was started roughly a week before estimated grain physiological maturity until several weeks after the
grain had reached harvest moisture. The two hybrids seemed to have no visual differences in field drying rates; hence, their
data were pooled for analysis. The stalk fraction had the highest moisture over the study period, but by the end, 213 days after
planting, all components of the corn plant reached nearly the same moisture content of 10% to 13% w.b. Moisture content
of the stover could be estimated by doubling the grain moisture content when the grain moisture was between 18% and 31%
w.b. After physiological maturity, the dry matter content of the stalk and husk fractions declined steadily. The leaf fraction
mass sustained substantial losses (about 74%) very rapidly, mainly due to wind and rain damage. The amount of dry stover
was about 50% of the total dry plant material over the monitoring period with stalks comprising 50% of the stover dry matter
at the time grain was harvested. These data for Tennessee conditions (southeastern U.S.) support use of the convenient 1-to-1
rule of thumb for estimating stover dry matter from grain dry matter, but strictly qualified to only when grain is at the typical
harvest range of 30% to 18% moisture.

Moisture and yield of corn stover fractions before and after grain maturity

Wood pellets made from sawdust and shavings are white in color and low in ash content. Pellets made from a mix of bark and white wood are darker in color, and bark increases the ash content of pellets. Steam treatment of biomass prior to pelletization improves the durability of pellets. Both wet (steam) and dry thermal (torrefaction) treatments of biomass darken the pellets. The off-color pellets have a lower commercial value than white wood pellets in residential applications. In this research, ground white wood (western Douglas fir, Pseudotsuga menziesii L.) was treated with saturated steam at 200°C and 220°C for 5 and 10 min. The colors of the treated and untreated powders and pellets were evaluated. The Hunter color coordinates L*, a*, and b* were recorded using a Minolta CM-5 spectrophotometer. Compared to untreated samples, the steam-treated samples became darker; the hues shifted from red to green and from blue to yellow. Multi-linear regression models of three color coordinates with elemental composition of carbon and hydrogen were developed. The values of L*, a*, and b* showed good correlation with percentage of carbon, hydrogen, and oxygen of the samples, with R2 values of 0.97, 0.99, and 0.97, respectively. The developed equations can be useful tools for the bioenergy industry for a quick estimation of fuel properties by a simple color measurement.

Colorimetry Applied to Steam-Treated Biomass and Pellets Made from Western Douglas Fir (Pseudotsuga menziesii L.)

This paper reviews a recent development in the heat and moisture transfer modeling for drying single layes of agricultural grains. A diffusion model with time-varying boundary condition predicts the complex shape of the drying curve well. A conduction model with evaporating boundary condition, when used with the Gamson correlation for convective heat transfer coefficient, accurately predicts experimental grain surface temperature. The new modewls were tested experimentally, drying wheat and barley in a thin-layer dryer useing 40 to 175 c air and the initial moisture ranging from 0.20 to 0.40 (decimal dry basis). It is shown that grain temperatures calculated by the conduction heat equation, when used in conjunction with a probit-type germination loss model, predict germination values different from those predicted by the lump heat equation.

Improved heat and mass transfer models to predict grain quality

In this study, the logistical resources required to develop a bioeconomy based on corn stover in the USA are quantified, including field equipment, storage sites, transportation and handling equipment, workforce, corn growers, and corn lands. These resources are essential to mobilize large quantities of corn stover from corn fields to biorefineries. The logistical resources are estimated over the lifetime of the biorefineries. Seventeen corn-growing states are considered for the logistical resource assessment. Over 6.8 billion gallons of cellulosic ethanol can be produced annually from 108 million dry tons of corn stover in these states. The maximum number of required field equipment (i.e., choppers, balers, collectors, loaders, and tractors) is estimated to be 194 110 units with a total economic value of about $26 billion. In addition, 40 780 trucks and flatbed trailers would be required to transport bales from corn fields and storage sites to biorefineries with a total economic value of $4.0 billion. About 88 899 corn growers need to be contracted with an annual net income of over $2.1 billion. About 1903 storage sites would be required to hold 53.1 million dry tons of inventory after the harvest season. These storage sites would take up about 35 320.2 acres and 4077 loaders with an economic value of $0.4 billion would handle this inventory. The total required workforce to run the logistics operations is estimated to be 50 567. The magnitude of the estimated logistical resources demonstrates the economic and social significance of the corn stover bioeconomy in rural areas in the USA. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Estimating the required logistical resources to support the development of a sustainable corn stover bioeconomy in the USA

Torrefaction, a thermal pretreatment process, is gaining attention as it improves biomass physical properties and chemical composition for recycling. During torrefaction, biomass is heated slowly in an inert environment to a maximum temperature of 300°C. The torrefaction process creates a solid uniform product with lower moisture and higher energy content than raw biomass. During torrefaction, moisture and some volatile organic compounds (VOCs) volatilize from the biomass. Depending on stoichiometry and other conditions, non-condensable gas species, including CO and CO2, are formed. Among the various torrefaction reactor designs, the moving bed reactor has gained attention as it is easy to operate and scale and helps produce a uniform torrefied product. However, there is a lack of literature on the torrefaction reactor design aspects and relevant design equations for estimating the dimensions of the torrefier based on its throughput. This article includes: (a) the impact of torrefaction on the product quality in terms of biomass physical properties and chemical composition; and (b) a model for designing a moving bed torrefier, considering fundamental heat and mass transfer calculations. This model includes a set of equations for basic calculations to configure the torrefaction reactor dimensions such as diameter and height of the moving bed torrefier for different capacities, based on target and calculated solids and gas velocities, residence times, and temperatures. The article also briefly describes the solid feed system, gas supply and recycle system, solid product management, torrefier gas monitoring, control system, and fugitive dust emissions control. Different moving bed torrefaction and gas recycle concepts are conceptualized to assess the features, advantages, and disadvantages of various design and operating concepts. These designs include example concepts for (a) vertical and horizontal torrefaction reactors; (b) torrefier gas recycle and oxidation of all or a portion of the torrefier off-gas; (c) counter and co-flowing gas and biomass in the torrefier; (d) controls for system temperatures, pressures, flow rates, and gas compositions; and (e) ability to sample the biomass feed, torrefied product, and gas streams for analysis as needed to investigate the thermal decomposition, physical behavior, and operational performance of the torrefaction system.

/pdf/biomass-torrefaction-process-product-properties-reactor-4i795oteqm.pdf

Shahab Sokhansanj

Papers

Moisture and yield of corn stover fractions before and after grain maturity

Colorimetry Applied to Steam-Treated Biomass and Pellets Made from Western Douglas Fir (Pseudotsuga menziesii L.)

Improved heat and mass transfer models to predict grain quality

Estimating the required logistical resources to support the development of a sustainable corn stover bioeconomy in the USA

Biomass Torrefaction Process, Product Properties, Reactor Types, and Moving Bed Reactor Design Concepts