Methane pyrolysis (MP), where CH4 is thermally decomposed to H2 and solid carbon is a CO2 free H2 production technique. By performing non-catalytic MP experiments in the temperature range of 1100°C-1700 °C we showed that the produced carbon nanoparticles (CNP) have a similar elemental composition (C, H, O, and N) and turbostratic nanostructure compared to rubber grade carbon black (CB) if the reactor temperature is ∼1400 °C with 100% conversion of the CH4 to CNP, C2H2, and H2 with product yields of ∼0.53 g/gfuel, ∼0.23 g/gfuel, and ∼0.24 g/gfuel, respectively. By increasing the reactor temperature above 1400 °C, further decomposition of the C2H2 to CNP and H2 occurs, and the theoretical yield of 0.75 g/gfuel of CNP and 0.25 g/gfuel H2 could be reached. However, the turbostratic nanostructure of the CNP at higher temperatures was too graphitized compared to rubber grade CB and instead more like electro conductive CB

In this article, the effects of calcination temperature and calcination atmosphere on the properties of the lime produced during flash calcination of industrial lime mud samples in a pilot-sized drop tube furnace have been studied. Flash calcination was performed at a wide range of temperatures between 800 and 1300 °C and different gas mixtures containing N<inf>2</inf>, CO<inf>2</inf>, and H<inf>2</inf>O in the calcination atmosphere. The effect of the calcination condition on the key conditions of the produced CaO, such as chemical composition, surface area, porosity, and particle morphology, has been shown. The addition of CO<inf>2</inf> to the inert atmosphere led to slower calcination rates and a higher onset temperature for the calcination, but no changes to morphology. Furthermore, the addition of H<inf>2</inf>O to the calcination atmosphere generally led to lower calcination rates at higher temperatures and smoother particles in comparison to CO<inf>2</inf> and N<inf>2</inf>

Pyrolysis oil (PO) derived from biomass has the potential to serve as a renewable feedstock for future carbon black (CB) production. However, its composition is significantly different from the fossil feedstocks currently used for CB manufacturing, as it contains higher concentrations of oxygen and water that might influence the yield and nanostructure of CB. In this article, we examine how the water content in PO affects the production of CB at high-temperature pyrolysis (1400-1600 °C) in an electrically heated entrained flow reactor. The main objective was to investigate the influence of water content on the yield and quality of the CB produced from upgraded PO with varying inherent water contents (0-20 wt %). The experiments in this work were performed with model compounds to simulate an upgraded PO. The produced CB was characterized by using several analytical techniques, including elemental composition, powder X-ray diffraction, transmission electron microscopy, and nitrogen physisorption. The results show a clear correlation between the water content in the PO feedstock and the output of CB, showing a reduced yield of CB as the water content increases. These results highlight the crucial role of feedstock composition in making PO a viable renewable feedstock for CB production.

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-% O2) and oxygen-enriched combustion conditions (40 vol-% and 60 vol-% O2). 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. © 2021 The Author(s)

In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime. 

The direct combustion of recyclable metals has the potential to become a zero-carbon energy production alternative, much needed to alleviate the effects of global climate change caused by the increased emissions of the greenhouse gas CO2. In this work, we show that the emission of CO2 is insignificant during the combustion of pulverized sponge iron compared to that of pulverized coal combustion. The emissions of the other harmful pollutants NOx and SO2 were 25 and over 30 times lower, respectively, than in the case of pulverized coal combustion. Furthermore, 96 wt % of the solid combustion products consisted of micrometer-sized, solid or hollow hematite (α-Fe2O3) spheres. The remaining 4 wt % of products was maghemite (Î-Fe2O3) nanoparticles. According to thermodynamic calculations, this product composition implies near-complete combustion, with a conversion above 98%. The results presented in this work strongly suggest that sponge iron is a clean energy carrier and may become a substitute to pulverized coal as a fuel in existing or newly designed industrial systems.

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.