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Renewable-based carbon black was produced using pyrolysis oil derived from pine and spruce stem wood as feedstock in a continuous, high-temperature spray process. The particle size, micro- and nanostructure of the carbon black particles were investigated using High Resolution Transmission Electron Microscopy. The effect of process parameters on the structural properties of the product was studied. Conditions that yielded products structurally similar to commercial carbon black were identified. The results indicate that biomass pyrolysis oil can be used as a feedstock to produce renewable-based carbon black in a continuous process that is flexible and scalable. The structural properties of the products depended on process temperature and were consistent with those of commercial carbon black. [ABSTRACT FROM AUTHOR]

Trace compounds were measured in synthesis gas and waste water from a pilot scale pressurized entrained flow oxygen blown biomass gasifier. The feedstock used was milled soft stem wood powder. Gaseous trace compounds were analyzed by gas chromatography. Up to 20 ppm of hydrogen sulfide was observed in the cold synthesis gas and the concentration seemed to be independent of the oxygen equivalence ratio (ER). Benzene varied from 30 to 1100 ppm, strongly depended on the ER and correlated well with the methane concentration. The concentrations of acetylene and ethylene increased as the ER was reduced and could have acted as precursors for the observed soot particles which were characterized using thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Common polycyclic aromatic hydrocarbons from high temperature biomass gasification such as pyrene, phenanthrene, fluoranthene, and naphthalene were observed in low concentrations in the soot, in the cold synthesis gas and also in the waste water from the quench. Inorganic elements from the feedstock were observed in the waste water. Comparisons were also made with previous results from a black liquor gasifier. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 699-705, 2014 [ABSTRACT FROM AUTHOR]

The fly ash formation during suspension combustion of five different biomass powders (stem wood, bark, forest residue, willow, and reed canary grass) and the corresponding products from fast pyrolysis (bio-oil and biochar) of the powders was investigated. The fifteen fuels were burned in a drop tube furnace under normal (20 vol-% O 2) and oxygen-enriched combustion conditions (40 vol-% and 60 vol-% O 2). The trends in the data were used to discuss differences in combustion behavior and devise recommendations for the use of the fuels. There was a general difference in fly ash formation mechanism between the solid fuels (biomass and biochar) and the bio-oil fuels, which was attributed to parts of the ash-forming elements in bio-oil being dissolved in the oil. Oxygen-enrichment did not affect the release of inorganic elements to the gas phase for bio-oil combustion. Since the bio-oils generate lower fly ash during combustion, ~100 times compared to the original biomasses, they should be reserved for combustion technologies demanding fuels with very low ash content, whereas the biochar should be used in large scale combustion facilities with advanced gas cleaning technology operated by teams with experience of handling ash related operational problems. • Bio-oil combustion generate low particle emissions compared to biomass combustion. • Biochar combustion generate high particle emissions compared to biomass combustion. • Oxygen enriched combustion increase ash vaporization during solid fuel combustion. • Submicron particles from bio-oil combustion contains also refractory elements. [ABSTRACT FROM AUTHOR]

The influence of operating condition on particle formation during pressurized, oxygen blown gasification of wood powder with an ash content of 0.4 wt% was investigated. The investigation was performed with a pilot scale gasifier operated at 7 bar(a). Two loads, 400 and 600 kW were tested, with the oxygen equivalence ratio ( λ ) varied between 0.25 and 0.50. Particle concentration and mass size distribution was analyzed with a low pressure cascade impactor and the collected particles were characterized for morphology, elemental composition, nanostructure, and reactivity using scanning electron microscopy/high resolution transmission electron microscopy/energy dispersive spectroscopy, and thermogravimetric analysis. In order to quantify the nanostructure of the particles and identify prevalent sub-structures, a novel image analysis framework was used. It was found that the process temperature, affected both by λ and the load of the gasifier, had a significant influence on the particle formation processes. At low temperature (1060 °C), the formed soot particles seemed to be resistant to the oxidation process; however, when the oxidation process started at 1119 °C, the internal burning of the more reactive particle core began. A further increase in temperature ( > 1313 °C) lead to the oxidation of the less reactive particle shell. When the shell finally collapsed due to severe oxidation, the original soot particle shape and nanostructure also disappeared and the resulting particle could not be considered as a soot anymore. Instead, the particle shape and nanostructure at the highest temperatures ( > 1430 °C) were a function of the inorganic content and of the inorganic elements the individual particle consisted of. All of these effects together lead to the soot particles in the real gasifier environment having less and less ordered nanostructure and higher and higher reactivity as the temperature increased; i.e., they followed the opposite trend of what is observed during laboratory-scale studies with fuels not containing any ash-forming elements and where the temperature was not controlled by λ . [ABSTRACT FROM AUTHOR]

Particle properties such as size, shape and density play significant roles on particle flow and flame propagation in pulverized fuel combustion and gasification. A drop tube furnace allows for experiments at high heating rates similar to those found in large-scale appliances, and was used in this study to carry out experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion. The objective of this study was to develop a particle conversion model based on optical information on particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved to three narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized using optical methods. Different shape descriptors were evaluated and a shape descriptor based on particle perimeter was found to give significant information for accurate estimation of particle volume. The optical conversion model developed was proven useful and showed good agreement with conversion measured using a reference method based on chemical analysis of non-volatilized ash forming elements. The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoring of particle conversion, provided density data has been calibrated. [ABSTRACT FROM AUTHOR]