Mechanical Strength Of Pellets Research Articles

Investigation on internal structure of pellets with halloysite additive and effect of moisture content before the pelletizing process

The article presents analysis of the particle size distribution inside pellets and the influence of moisture content before pelletization process on final product mechanical strength. The following types of biomass were used without and with the content of additive (halloysite): Polish wheat straw – (SP-K), miscanthus (DM), cereal straw (DS) and herbaceous pellets (BZ). Particles inside pellets were characterized by a grain size smaller than 3 mm and the cumulative weight percent passing through the sieve with mesh screen 1 mm for each sample was higher than 70 %. The moisture content before pelletization process for tested materials was in the range of 25% - 30% depending on the material which was used, while values of mechanical strength of pellets were within the range of 77.7% - 96.2% (depending on the type of material and moisture content before the pelletization process).

Thermo-physical characterization of torrefied fuel pellet from co-pelletization of canola hulls and meal

Agricultural processing residues, as renewable sources of energy, can be converted to value-added products such as fuel pellets with the wide applications in the production of heat and power. In this research, densification/torrefaction of canola meal and canola hull was investigated. A bench-scale extruder was used for densification of canola hull and canola meal. Then, to increase the hydrophobicity and heating value of pellets, they were torrefied. For pelletization of canola meal, an increase in canola meal to water mass ratio resulted in an increase in the mechanical strength of pellets. Canola meal was also used to facilitate pelletization of canola hull. Co-pelletization of canola hull with canola meal was successful for canola hull mass percentage up to 60 wt% in the feedstock. In general, torrefied pellets showed lower moisture adsorption (up to 59%), higher carbon content (in the range of 21–25%), lower oxygen content (35–46%), and higher heating value (up to 22%) compared with their respective precursors. To study the effects of operating conditions and additives, different characterization techniques were used to evaluate the thermal, chemical, mechanical, and physical properties of pellets. Synchrotron-based computed tomography showed that after torrefaction, porosity increased by 10% for pellets from canola meal and increased by 22–30% for pellets prepared by co-pelletization. Addition of alkali lignin to canola meal precursor helped to increase the mechanical strength of torrefied pellet produced from canola meal. The use of binders such as alkali lignin and crude glycerol had no effect on the relaxed density of torrefied pellets and resulted in higher moisture adsorption.

Assessment of the energetic and mechanical properties of pellets produced from agricultural biomass

This paper presents an assessment of the energetic and mechanical properties of pellets produced from agricultural biomass. For the production of pellets the following raw materials were used: wheat straw, rape straw, and maize straw. Additionally, the mixtures of wheat-rape straw, wheat-maize straw, and rape-maize straw (each accounting for 50% of the mass) were applied. The studied resources were ground with the use of a universal shredder driven by a 7.5 kW electric engine. A pelleting machine fitted with a fixed flat matrix with two driven thickening rolls was used to produce the pellets. Analyses of the moisture and calorific value of resources as well as the bulk density and mechanical strength of pellets were performed according to biding standards. The moisture of resources ranged from 16.5% to 18.5% for rape and maize straw, respectively. The average calorific value fluctuated between 15.3 MJ kg−1 for a mixture of wheat and rape straw to 16.2 MJ kg−1 for maize straw. The bulk density and mechanical strength of pellets depended on the type of resources used. The lowest bulk density was recorded for wheat straw pellets (386–420 kg m−3), and the highest (561–572 kg m−3) for maize straw pellets. The lowest mechanical strength of pellets was noted for rape (95.4–96.8%), whereas the highest was for pellets made from a wheat and maize straw mixture (96.8–98.9%).

Amine modified and pelletized mesoporous materials: Synthesis, textural–mechanical characterization and application in adsorptive separation of carbondioxide

Adsorption-mediated CO2 separation can reduce the cost of carbon capture and storage. Amine modified sorbents are promising candidates for carbon capture. To investigate the details of CO2 adsorption, three types of mesoporous materials, MCM-41, MCM-48 and SBA-15 were synthesized, pelletized and further pellets were impregnated with 50wt.% of polyethyleneimine (PEI) in methanol to evaluate the performances of the materials in terms of CO2 adsorption. The powdered mesoporous materials were also impregnated with 50wt.% of PEI. The materials were characterized by XRD, TGA, FT-IR, SEM, TEM, N2-physisorption and BET techniques. The mechanical strength of pellets was examined by vertical crushing method. The surface area, pore volume and pore diameter of pellets were lower than powdered materials. This decrease may be due to partial blocking of pore entry and surface coverage of additives during shaping of pellets. A detailed TGA study is carried out of pellets by varying the composition to optimized the wt.% composition of the different ingredients to attain the maximum mechanical strength and high adsorption of CO2. All the PEI-loaded pelletized materials exhibited substantially higher reversible CO2 adsorption–desorption behaviors with >99% recovery. The results indicate pellets containing methyl cellulose and activated carbon show better mechanical strength and CO2 adsorption. The above study also proved that MCM-48 is a better material as compared to MCM-41 and SBA-15 for pelletization and loading of PEI. The material with 50wt.% loading of PEI on MCM-48, showed maximum adsorption of 1.094W/W0 at 80°C with an impressive mechanical strength of 6.1MPa.

Analysis of mechanical strength in ceramic pellets of nuclear fuel

The mechanical strength of sintered uranium oxide (UO2) pellets was determined by subjecting them to Brazilian testing. The results showed that the sintering time, the sintering atmosphere as well as the annealing process after grinding all had a great influence on the mechanical strength of the pellets. Pellets sintered for the longest time reached the highest density among four pellet types, even though their mechanical resistance was not the highest. Annealed pellets, sintered in a dry atmosphere, had a resistance of about 10% higher than the annealed pellets sintered in a wet atmosphere. For the pellets with similar densities (‘B’ and ‘D’), the difference in their mechanical strength was due to differences in the sintering atmosphere, which influenced the porosity distribution. All annealed pellets had superior properties compared with those that were only ground and not annealed, proving that annealing does indeed improve the mechanical strength of UO2 pellets.