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Lignocellulosic biomass from energy crops, i.e., short rotation coppice willows such as Salix spp., can be used as feedstock to produce transportation biofuels. An attractive thermochemical route for the introduction of large-scale production of biofuels in the transport sector in the near future is to convert the biomass to a liquid (pyrolysis oil) via fast pyrolysis followed by co-processing with fossil oil in existing refinery infrastructures. In this study, Salix was first liquefied using ablative fast pyrolysis in a pilot scale unit. The resulting pyrolysis oil, rich in oxygenates, was co-refined in 20 wt.% ratio with fossil feedstocks using two different technologies, a fluidized catalytic cracking (FCC) laboratory unit, and a continuous slurry hydroprocessing pilot plant. In the FCC route, the pyrolysis oil was cracked at 525 °C using a commercial FCC catalyst at atmospheric pressures and resulted in significant deoxygenation (97 wt.%). To determine the biogenic carbon in the co-refined liquid product, C14 analysis was conducted. The whole conversion route resulted in 11 wt.% of the biogenic carbon from Salix ended up in liquid products, the rest being gaseous products, bio-char from the pyrolysis, and coke (16 wt.%) from the FCC upgrading. The hydroprocessing was conducted at 420 °C, at a hydrogen pressure of 150 bars at a liquid hourly space velocity of 0.67 h-1, in the presence of an unsupported molybdenum sulfide catalyst. The hydroprocessing resulted also in significant deoxygenation of the liquid product (93 wt.%). The whole conversion route resulted in 26 wt.% of the biogenic carbon from Salix ending up as liquid hydrocarbons, the rest was mainly gaseous hydrocarbons, carbon oxides, and bio-char. The study showed that it is feasible to co-refine pyrolysis oil using both methods, the main difference being that hydroprocessing results in a significantly higher yield of hydrocarbon products but also would require an input of H2 while in the cracking route a significant part ends up as gas and as coke on the catalyst. The choice of routes is foremost dependent on the available amount of bio-oil and refining infrastructures. Besides liquid biofuel, it is also vital to utilize the biogenic carbon material in the bio-char and in the gaseous products.

Co-refining of fast pyrolysis bio-oil together with fossil oil in existing refinery infrastructure is an attractive and cost-efficient route to conversion of lignocellulosic biomass to transportati...

Earlier studies show that co-pyrolysis of biomass and plastics can improve the quantity and quality of the produced pyrolysis oil compared to pyrolysis of the separate feedstocks. In this work thre ...

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.

Understanding of the interaction between cellulose and various plastics is crucial for designing waste-to-energy processes. In this work, co-pyrolysis of polystyrene (PS) and cellulose was performed in a Py-GC×GC/MS system at 450–600 °C with ratios 70:30, 50:50, and 30:70. Polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) were then added to the mixture with different ratios. It was found that co-pyrolysis of PS and cellulose promotes the formation of aromatic products with a large increase in the yield of ethylbenzene as compared to the calculated value from individual feedstock. This indicates interactions between cellulose and PS pyrolysis products. Observations from experiments including more than one type of plastics indicate that the interactions between different plastics are more pronounced than the interaction between plastics and cellulose.

In order to reduce ash related operational problem and particle emissions during pyrolysis oil combustion it is important to produce pyrolysis oil with very low concentration of inorganics. In this paper, the distribution of all major inorganic elements (S, Si, Al, Ca, Fe, K, Mg, Mn, Na, P, Ti and Zn) in the pyrolysis products (solid residue and two fractions of pyrolysis oil) was investigated during pyrolysis of stem wood, bark, forest residue, salix and reed canary grass. The raw materials were pyrolysed in a cyclone reactor and the produced pyrolysis oils were recovered as two oil fractions, a condensed fraction and an aerosol fraction. The inorganic composition of the ingoing raw material, the solid residue and the two pyrolysis oil fractions were analysed with inductively coupled plasma spectrometry techniques. All major inorganic elements, except sulphur, were concentrated in the solid residue. A significant amount of sulphur was released to the gas phase during pyrolysis. For zinc, potassium and iron about 1–10 wt% of the ingoing amount, depending on the raw material, was found in the pyrolysis oil. For the rest of the inorganics, generally less than 1 wt% of the ingoing amount was found in the pyrolysis oil. There were also differences in distribution of inorganics between the condensed and the aerosol oil fractions. The easily volatilized inorganic elements such as sulphur and potassium were found to a larger extent in the aerosol fraction, whereas the refractory elements were found to a larger extent in the condensed fraction. This implies that oil fractionation can be a method to produce oil fractions with different inorganic concentrations which thereafter can be used in different technical applications depending on their demand on the inorganic composition of the pyrolysis oil.

Pyrolysis oil is a complex mixture of different chemical compounds with a wide range of molecular weights and boiling points. Due to its complexity, an efficient fractionation of the oil may be a more promising approach of producing liquid fuels and chemicals than treating the whole oil. In this work a sampling system based on fractional condensation was attached to a cyclone pyrolysis pilot plant to enable separation of the produced pyrolysis vapors into five oil fractions. The sampling system was composed of cyclonic condensers and coalescing filters arranged in series. The objective was to characterize the oil fractions produced from three different Nordic feedstocks and suggest possible applications. The oil fractions were thoroughly characterized using several analytical techniques including water content; elemental composition; heating value, and chemical compound group analysis using solvent fractionation, quantitative 13C NMR and 1H NMR and GC x GC − TOFMS. The results show that the oil fractions significantly differ from each other both in chemical and physical properties. The first fractions and the fraction composed of aerosols were highly viscous and contained larger energy-rich compounds of mainly lignin-derived material. The middle fraction contained medium-size compounds with relatively high concentration of water, sugars, alcohols, hydrocarbonyls and acids and finally the last fraction contained smaller molecules such as water, aldehydes, ketones and acids. However, the properties of the respective fractions seem independent on the studied feedstock types, i.e. the respective fractions produced from different feedstock are rather similar. This promotes the possibility to vary the feedstock depending on availability while retaining the oil properties. Possible applications of the five fractions vary from oil for combustion and extraction of the pyrolytic lignin in the early fractions to extraction of sugars from the early and middle fractions, and extraction of acids and aldehydes in the later fractions.

Fast pyrolysis of biomass results in a renewable product usually denoted pyrolysis oil or bio-oil, which has been suggested to be used as a direct substitute for fuel oil or as a feedstock for production of transportation fuels and/or chemicals. In the present work, fast pyrolysis of stem wood (originated from pine and spruce), willow, reed canary grass, brown forest residue and bark has been performed in a pilot scale cyclone reactor. The experiments were based on a biomass feeding rate of 20 kg/h at three different reactor temperatures. At the reference condition, pyrolysis of stem wood, willow, reed canary grass, and forest residue resulted in organic liquid yields in the range of 41 to 45% w /w, while pyrolysis of bark resulted in lower organic liquid yields. Two fractions of pyrolysis oil were obtained, denoted as the condensed and the aerosol fraction. Most of the water soluble molecules were collected in the condensed fraction, whereas the yield of water insoluble, heavy lignin molecules was higher in the aerosol fraction. Based on the results of the present work, willow, reed canary grass and forest residue are considered as promising raw materials for production of pyrolysis oil in a cyclone reactor.

The performance of a high-temperature pressurized black liquor gasifier intended for fuel or power production was evaluated both by thermochemical equilibrium calculations and with experiments performed in a development plant with a maximum capacity corresponding to 3 MWth. The aim of this paper was to investigate how the energy efficiency and the performance of the gasifier change with desired use of the syngas and to provide an accurate process analysis which can be used in future work for process optimization and understanding. Experiments in the plant were performed for an oxygen equivalence ratio (λ) between 0.414–0.462 at two system pressures, 24.6 and 28.7 bar, respectively. The thermal load on the gasifier was 2.7 MWth during the experiments. The experimentally verified cold gas efficiency taking into account all gaseous species varied between 59.0–62.4%. However, if only CO and H 2 (which are the effective molecules for synthetic fuel production) were taken into account; the cold gas efficiency decreased considerably to 53.7–55.4% due to the presence of CH 4 in the gas. The results indicate that optimal performance for synthetic fuel production occurs at a higher λ compared to power production. There is also a potential to further improve the performance for an optimal operated commercial plant in the future since the theoretical results indicate that the cold gas efficiency could be as high as 68.8% (λ = 0.35) for fuel production and 81.7% (λ = 0.27) for power production.

Fast pyrolysis of stem wood was performed in a pilot-scale cyclone reactor with a reactor wall temperature of ∼750 °C. Wood powder was introduced to the pyrolyzer at 20 kg/h during the experiments. Stable operation of the pyrolyzer was easily achieved, and the resulting yields of the products were 54.6 wt % of pyrolysis oil, 15.2 wt % of solid residue, and 20.1 wt % of gases. From the ingoing raw material, 3.4 wt % of the mass could be recovered as deposits, mainly on the walls of the reactor and in the oil condensing part of the plant. The mass and energy balance closures were approximately 93% and 89%, respectively. The physicochemical properties of the pyrolysis oil, solid residue, and noncondensable gas were measured and compared to values in the literature. The results also show that it is possible to produce an oil with a very low concentration of ash-forming elements because particle separation has already occurred in the cyclone reactor.

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

Biomass fast pyrolysis vapors contain a significant quantity of persistent aerosols, which can impact downstream processing by e.g. fouling of surfaces and deposition on downstream catalysts. In this study, aerosol concentrations and size distributions were measured by an impactor in two pyrolysis systems, a bench-scale fluidized-bed pyrolyzer and a pilot-scale cyclone pyrolyzer. In both units, the mass-based mode aerosol diameter was approximately 1 μm before aerosol collection devices in cooled vapors of 300–370 K but the number-based median was 1 μm deposited during cooling of pyrolysis vapors from 620 to 370 K in the fluidized-bed pyrolysis system. The oil fraction collected from the aerosols constituted approximately 40 wt% of the total oils collected in both systems. Compared to the total collected oil, the oil fraction from the aerosols was enriched in lignin-derived components and anhydrosugars and had lower concentrations of low molecular weight cellulose derived oxygenates, such as hydroxyketones.

Renewable fuels could in the future be produced in a biorefinery which involves highly integrated technologies. It has been reported that thermochemical conversion (gasification) of lignocellulosic biomass has a high potential for end production of renewable biofuels. In this work, lignin residue from biochemical conversion of wheat straw was gasified in an oxygen blown pressurized entrained flow gasifier (PEBG) at 0.25–0.30 MWth, 0.45 2 ), carbon monoxide (CO) and carbon dioxide (CO 2 ) were the main gas components with H 2 /CO ratios varying during the gasification test (0.54–0.63). The methane (CH 4 ) concentration also varied slightly and was generally below 1.7% (dry and N 2 free). C 2 -hydrocarbons ( 2 S, 2 ) and Berlinite (AlPO 4 ) and Na, Ca, Mg, K and Fe in lower concentrations. Cooling of the burner will be necessary for longer tests to avoid safety shut downs due to high burner temperature. The cold gas efficiency and carbon conversion was estimated but more accurate measurements, especially the syngas flow, needs to be determined during a longer test in order to obtain data on the efficiency at optimized operating conditions. The syngas has potential for further upgrading into biofuels, but will need traditional gas cleaning such as acid gas removal and water gas shifting. Also, higher pressures and reducing the amount of N 2 is important in further work.

Pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals and/or fuels. The objective of the present paper was to characterize fast pyrolysis products and to study pyrolysis oil fractionation. The products were obtained from different Nordic forest and agricultural feedstocks in a pilot scale cyclone pyrolysis plant at three different reactor temperatures. The results show that the main elements (C, H and O) and chemical compositions of the products produced from stem wood, willow, forest residue and reed canary grass are in general terms rather similar, while the products obtained from bark differ to some extent. The oil produced from bark had a higher H/Ceff ratio and heating value which can be correlated to a higher amount of pyrolytic lignin and extractives when compared with oils produced from the other feedstocks. Regardless of the original feedstock, the composition of the different pyrolysis oil fractions (condensed and aerosol) differs significantly from each other. However this opens up the possibility to use specifically selected fractions in targeted applications. An increased reactor temperature generally results in a higher amount of water and water insoluble material, primarily as small lignin derived oligomers, in the produced oil.