Progress in biomass torrefaction: Principles, applications and challenges

Biomass torrefaction technology: Techno-economic status and future prospects

Oxy-fuel combustion of pulverized fuels: Combustion fundamentals and modeling

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Status overview of torrefaction technologies

Emissions of SO2, NOx, CO2, and HCl from Co-firing of coals with raw and torrefied biomass fuels

This study examined and compared the effect of torrefaction on the heating value, elementary composition, and chlorine content of eight woody biomasses. The biomass samples were torrefied in a specially constructed batch reactor at 260 °C for 30, 60, and 90 min. The original biomasses as well as the solid, liquid, and gaseous torrefaction reaction products were analyzed separately. The higher heating values (HHV) of dry samples increased from 19.5–21.0 MJ  kg−1 to 21.2–23.2 MJ  kg−1 during 60 min of torrefaction. In all samples, the HHV increased 9 % on average. Furthermore, the effect of torrefaction time on the biomass HHV was studied. Measurements showed that after a certain point, increasing the torrefaction time had no effect on the samples' HHV. This optimal torrefaction time varied considerably between the samples. For more reactive biomasses, i.e., birch and aspen, the optimal torrefaction time was close 30 min whereas the HHV of less reactive biomasses, e.g., stumps, increased markedly even after a 60-min torrefaction. Another significant observation was that torrefaction reduced the chlorine content of the biomass samples. The chlorine concentration of the solid product dropped in most samples from the original by half or even as much as 90 %. The highest relative chlorine decrease was observed in the Eucalyptus dunnii sample, which also had the highest chlorine content of all the studied biomasses. The relative carbon content of the biomass samples increased during torrefaction as the average elementary composition changed from CH0.123O0.827 to CH0.105O0.674 after a 60-min torrefaction.

The effect of torrefaction on the chlorine content and heating value of eight woody biomass samples

Fast pyrolysis of coal, peat, and torrefied wood: Mass loss study with a drop-tube reactor, particle geometry analysis, and kinetics modeling

Techno-economic analysis of four concepts for thermal decomposition of methane: Reduction of CO2 emissions in natural gas combustion

The purpose of the study was to compare torrefaction to partial pyrolysis conducted with a fast heat treatment process. Both torrefaction and the fast heat treatment tests were performed in a bubbling fluidized bed reactor. The study investigated the anhydrous weight losses, the fine grinding energy requirements, and the lower heating values of the samples produced with the two methods i.e. torrefaction and the fast heat treatment. The effect of particle size to these quantities was also investigated. The measurements demonstrated that the fine grinding energy requirement decreased rapidly as a function of anhydrous weight loss. The overall energy content remaining in the solid product decreased linearly as a function of anhydrous weight loss. The study shows that there is only little difference in the final products of the two processes when using particle sizes less than 4 mm. This means that it is possible to get similar products from the fast heat treatment process that takes only seconds compared to the slower torrefaction process that takes minutes.

Comparing the energy required for fine grinding torrefied and fast heat treated pine.

An experimental study and numerical modeling of combusting two coal chars in a drop-tube reactor: A comparison between N2/O2, CO2/O2, and N2/CO2/O2 atmospheres

Risto Raiko

Papers

The effect of torrefaction on the chlorine content and heating value of eight woody biomass samples

Fast pyrolysis of coal, peat, and torrefied wood: Mass loss study with a drop-tube reactor, particle geometry analysis, and kinetics modeling

Techno-economic analysis of four concepts for thermal decomposition of methane: Reduction of CO2 emissions in natural gas combustion

Comparing the energy required for fine grinding torrefied and fast heat treated pine.

An experimental study and numerical modeling of combusting two coal chars in a drop-tube reactor: A comparison between N2/O2, CO2/O2, and N2/CO2/O2 atmospheres