Natural binders and solid bridge type binding mechanisms in briquettes and pellets made from corn stover and switchgrass.

Lignocellulosic biomass is the most abundant and renewable material in the world for the production of biofuels. Using lignocellulosic biomass derived biofuels could reduce reliance on fossil fuels and contribute to climate change mitigation. A profound understanding of the physicochemical properties of lignocellulosic biomass and the analytical characterization methods for those properties is essential for the design and operation of associated biomass conversion processing facilities. The present article aims to present a comprehensive review of physicochemical properties of lignocellulosic biomass, including particle size, grindability, density, flowability, moisture sorption, thermal properties, proximate analysis properties, elemental composition, energy content and chemical composition. The corresponding characterization techniques for these properties and their recent development are also presented. This review is intended to provide the readers systematic knowledge in the physicochemical properties of lignocellulosic biomass and characterization techniques for the conversion of biomass and the application of biofuels.

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Review of physicochemical properties and analytical characterization of lignocellulosic biomass

Physical properties of pellets made from sorghum stalk, corn stover, wheat straw, and big bluestem

https://www.fpl.fs.fed.us/documnts/pdf2013/fpl_2013_liu003.pdf

The properties of pellets from mixing bamboo and rice straw

Biomass raw materials are widely regarded as a significant source of renewable energy, which significantly reduces the dependence on traditional fossil fuels, especially in the case of countries that are able to obtain biomass from various sources. Recently, pelletization has been widely used for mass and energy densification of biomass to overcome the problems associated with raw material use. As the global pellet market has developed quickly, the use of wood residues became no longer sufficient to fulfill the market needs. The standards of pellets provide limits for both physical and mechanical characteristics of produced pellets. Characteristics of produced pellets depend mainly on the feedstock characteristics as particle size and moisture content and operating conditions as applied pressure and die temperature. Thus, this paper provides rich information on the factors affecting the physical and mechanical properties of granules included in pellets. The main goal of the paper is to review the latest and comprehensive research on the physical and mechanical properties of most types of single and mixed pellets from biomass. The analysis of the effect of properties, adhesives, humidity, pressure and temperature as well as the physical and mechanical properties of the pellets studied was carried out. In addition, the critical and optimal values of various factors for different materials in which the following is of importance: high quality of pellets and biomass from which they are produced were analyzed. The principle and effect of applying post-production conditions as steam explosion and torrefaction on the characteristics of the pellets were reviewed in details. Moreover, this study proposes some recommendations for further development of the pelletization analysis and characteristics.

The significance of pelletization operating conditions: An analysis of physical and mechanical characteristics as well as energy consumption of biomass pellets

Switchgrass was pelleted through a 4.76 mm (3/16 in.) diameter die. The physical characteristics of the pellets were measured. It was found that the bulk density, particle density, durability, and hardness of the pellets were significantly affected by moisture content. The maximum values of bulk density and particle densities were 708 and 1462 kg/m3, respectively. The force required to rupture the pellets varied from 32 N at 6.3% moisture content to 22 N at 17.4% moisture content. Durability of the pellets was also affected by moisture content and was maximum at 8.6% (wet basis) moisture content. The pellets absorbed moisture at rates that were significantly affected by air relative humidity (P < 0.05). The EMC-ERH data for the pellets were sigmoidal in shape and were best predicted by the modified Chung-Pfost equilibrium moisture equation.

Moisture Effect on the Physical Characteristics of Switchgrass Pellets

Switchgrass and poultry litter are feedstocks that can be developed in the state of
Alabama for bioenergy applications. Both feedstocks are however, lightly dense and therefore not
economical to transport them from the site of production to places where they can be effectively
utilized, hence the need to densify them by pelleting. In order to develop the optimal pelletization
method for these feedstocks, fundamental studies were carried out on the effect of process
parameters (moisture content, temperature and die size) on pellet formation quantified by pellet
density and specific energy required to make the pellets in a single die system. Pellets were
manufactured by attaching a single die to a universal testing machine operated at constant speed. 
Results obtained showed that at compaction forces of 350 and 400 kg, the density of the switchgrass
and poultry litter pellets increased with die sizes of 4.8mm to 7.9mm. Density also increased with
increasing temperature from 60 to 90C. Density was also affected by the moisture content of the
feed material. There was no significant effect of temperature on the specific energy used to make
switchgrass pellets. The density of the switchgrass pellets varied from 850 kg/m3 to 1250 kg/m3 and
1350 kg/m3 to 1500 kg/m3 for poultry litter pellets. The specific energy needed for switchgrass
pellets varied from 19 kJ/kg to 90kJ/kg.

D. Bransby

Papers

Moisture Effect on the Physical Characteristics of Switchgrass Pellets

Compaction Behavior of Poultry Litter and Switchgrass