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Infrared radiation drying behaviors of four typical biomass briquettes (populus tomentosa leaves, cotton stalk, spent coffee grounds and eucalyptus bark) were investigated based on a lab-scale setup. The effect of radiation source temperatures (100–200 °C) on the far-infrared drying kinetics and heat transfer of the samples was addressed. As the temperature went up from 100 °C to 200 °C, the time required for the four biomass briquettes drying decreased by about 59–66%, and the average values of temperature for the four biomass briquettes increased by about 33–39 °C, while the average radiation heat transfer fluxes increased by about 3.3 times (3.7 times only for the leaves). The specific energy consumptions were 0.622–0.849 kW h kg −1 . The Modified Midilli model had the better representing for the moisture ratio change of the briquettes. The values of the activation energy for the briquettes in the first falling rate stage were between 20.35 and 24.83 kJ mol −1 , while those in the second falling rate stage were between 17.89 and 21.93 kJ mol −1 . The activation energy for the eucalyptus bark briquette in two falling rate stages was the least one, and that for the cotton stalk briquette was less than that for the rest two briquettes.

This study investigated the effect of shrinking and non-shrinking biomass geometries in a fixed bed reactor. Model simulation was performed to analyze the effect of biomass moisture content, gasification temperature, air flow rate, oxygen content in the primary air, and mass transfer coefficient on product yield for spherical, tabular, and cylindrical biomass briquettes. The model matched well with the experimental data. The production of hydrogen and carbon dioxide increased with an increase in moisture content. With an increase in gasification temperature, the water–gas shift reaction proceeded faster than the Boudouard reaction, leading to a decrease in the carbon dioxide composition and an increase in the carbon monoxide composition. Tabular shrinking particles with a H2/CO ratio of 1.44 and a CO/CO2 ratio of 0.22 at 1175 K were more favorable for producing value-added chemicals than the particles of all other geometries. The non-shrinking spherical particles had the highest low heating value (LHV) of 4.65 MJ/m3, whereas the tabular non-shrinking particles had the lowest LHV of 1.33 MJ/m3 among the shrinking and non-shrinking particles with all the other geometries considered. The gasification temperature was the most sensitive parameter, whereas moisture content and the mass transfer coefficient were the least sensitive parameters.

In the current world, the large consumption of fossil fuel leads to some global environmental problems, using biomass energy is one of the good solutions. However, due to the more strict emission policy, the sulphur releasing during biomass combustion cannot be ignored. In order to study the self-sulphur retention characteristics, the briquetting process of biomass is carried out. In this study, a batch of biomass briquettes combustion experiments are conducted to investigate self-sulphur retention characteristics. Five kinds of biomass powder, biomass briquettes, and briquettes with additive samples are used to carry out the combustion experiments, which are performed in a lab-scale tube furnace system. The influence of the briquetting process, reaction temperature, added coal and additives are studied comprehensively. The briquetting process gives remarkable enhancements on sulphur retention characteristics compare to the raw biomass powder, which is mainly due to the effect of the structural transformation. The enhancement are 35.00%, 76.68%, 36.15%, 27.34% and 31.36% compared to the original biomass samples. The reaction temperature behaves severely on the release of sulphur, that when the reaction temperature reaches 900 ∘ C , the sulphur release ratio starts to sharply increase. Adding coal into the biomass samples can increase the sulphur retention ability and the caloric value. The effects of different additives on sulphur retention ratios are also studied, exhibiting opposite trends as temperature increased. The organic Ca-based additives show better performance to enhance the self-sulphur retention ability. What's more, the potassium-based additives have a higher improvement than the calcium-based ones. The mechanism on sulphur retention of biomass briquettes with or without additives is also discussed. This study develops insightful understand on biomass self-sulphur retention ability, and its behaviours under the effect of the briquetting process, reaction temperature, added coal or additives, which could use as a guild for biomass briquetting combustion.

The suitability of using biomass briquettes to substitute coal is debatable, as a substantial amount of energy is required for briquetting of biomass. In the present work, an attempt to evaluate the energetic viability of briquetting of agricultural residues compared with the energy embodied in coal in India has been made. Briquetting of agricultural residues is not found to be an energetically viable option even for locations at a distance of about 1500 km from the coal pithead (even if the briquetting unit is located very close to the place of availability of the agricultural residues). A need for transportation of agricultural residues further pushes this critical distance upwards.