Torrefied Biomass Research Articles

Torrefied biomasses in a drop tube furnace to evaluate their utility in blast furnaces

Torrefaction and burning characteristics of bamboo, oil palm, rice husk, bagasse, and Madagascar almond were studied and compared with a high-volatile bituminous coal using a drop tube furnace to evaluate the potential of biomass consumed in blast furnaces. Torrefaction at 250 and 300°C for 1h duration was carried out. Analysis using the ash tracer method indicated that the extent of atomic carbon reduction in the biomasses was less than that of atomic hydrogen and oxygen. Torrefaction also lowered the sulfur content in bamboo and oil palm over 33%. An examination of the R-factor and burnout of the samples suggests that more volatiles were released and a higher burnout was achieved with raw and torrefied biomasses at 250°C than at 300°C; however, torrefaction at 300°C is a feasible operating condition to transform biomass into a solid fuel resembling a high-volatile bituminous coal used for blast furnaces.

Effects of temperature and holding time during torrefaction on the pyrolysis behaviors of woody biomass

Torrefaction is the thermal treatment techniques performed at relatively low temperature (<300 °C) in an inert atmosphere, which aims to improve the fuel properties attractively. In this study, woody biomass ( Leucaena leucocephala) was torrefied at various temperatures and holding times and the pyrolysis behaviors of the torrefied wood were examined in detail by using TG–MS technique. It was found that the carbon content and the calorific value of the torrefied leucaena increased significantly when temperature and holding time during the torrefaction increased. From the TG–MS analysis, the pyrolysis behaviors of the torrefied leucaena were significantly different from those of the raw leucaena. The char yield at 800 °C for the torrefied leucaena was increased when increasing the holding time during the torrefaction. On the other hand, the tar yield during the pyrolysis decreased significantly with the increase in the holding time during the torrefaction. Through the results from the TG–MS analysis, it was concluded that the structure of leucaena was changed by the torrefaction at temperature below 275 °C and the cross-linking reactions occurred during the pyrolysis resulting in increase in char yields and decrease in tar yields. It was also suggested that the longer the holding time during the torrefaction, the more the cross-linking reactions proceed during the pyrolysis. The results obtained from the study provide the basic information for the pyrolyser and/or gasifier design by using torrefied biomass as a fuel.

Flexible integrated gasification co-generation facilities A technical and energy analysis

Abstract The aim of this study was to identify and analyse the technical and energy impacts of feedstock and product flexibility on integrated gasification co-generation facilities (IGCF) using current commercial ready technologies. The evaluation was twofold: 1) to identifying bottlenecks and possible de-bottleneck solutions and 2) to analyse flexibility effects on overall plant performance. Results indicate that flexibility is technically possible. Overall plant performance shows a minor drop in efficiency when switching from coal to Eucalyptus. When using torrefied biomass this drop almost completely disappears.

98/00527 Combustion and inorganic emissions of ground waste tires

This work contrasted gaseous emissions of carbon, sulfur and nitrogen oxides from combustion of several types of biomass including woody, herbaceous and crop-derived wastes, pulverized in the size range of 75–150 μm. Both raw and torrefied biomass were exposed to high heating rates (104–105 K/s) in a laboratory-scale electrically-heated drop-tube furnace, operated at 1400 K. Combustion occurred under fuel-lean conditions. Torrefied biomass has lower volatile matter content, higher fixed carbon content and higher heating value than raw biomass. Results revealed that (a) CO2 emission factors from torrefied biomass were higher than those from raw biomass, reflecting the higher carbon content of the former, however there was no uniform trend in emission factors (kg/GJ); (b) SO2 emission factors of torrefied biomass were lower than those from raw biomass, even if some torrefied biomass types contained higher sulfur mass fractions than their raw biomass precursors. All raw and torrefied biomass, with one exemption, generated lower SO2 emission factors than a typical sub-bituminous coal; (c) torrefied biomass has higher fuel-nitrogen mass fractions than their raw biomass precursors; however, there was no clear trend in NOx emission factors between raw and torrefied biomass, as torrefied herbaceous and woody biomass types generated higher while torrefied crop biomass types generated lower emission factors than their raw biomass precursors. Comparing with the sub-bituminous coal, some raw and torrefied biomass types generated lower and some higher NOx emission factors. Overall, combustion of most types of biomass, either in raw or torrefied state, can result in lower SO2 and NOx emissions factors than those of typical western US sub-bituminous coals while, in principle, generating minimal net emissions of carbon.

Native copper

Biomass powders, in both raw and thermally treated (torrefied) form, are used in 100% biomass fired or in coal co-fired plants for power generation. They pose significant fire and explosion risks during storage, handling, processing and combustion, and therefore their explosibility characteristics need to be assessed for the design of safe systems and operations. Wood biomass powders are difficult to characterise for explosibility through standard methods because of their bulky and fibrous nature. This has resulted in the lack of reliable data on the explosibility of these materials. In this study we present a new methodology – with example measurements – for the determination of the minimum explosible concentrations (MECs) of raw and torrefied wood biomass powders, using a modified Hartmann tube. This equipment can also be used as a fast screening tool for the determination of other reactivity parameters, such as flame speeds and rates of pressure rise, through which the most reactive mixture can be identified for more detailed measurements in the larger ISO 1 m3 vessel. MEC measurements reported in this paper showed that both raw and torrefied pulverised wood biomass, were explosible at equivalence ratios as low as 0.2. This was one-third (1/3) the corresponding concentration for Kellingley coal (measured with the same method). Flame speeds 5–10 times higher than those of coal were measured for biomass. Flame speed differences will also have a direct effect on burner performance and flame stability for systems originally designed to burn coal and now firing biomass without modifications.