Pyrolysis Of Bark Research Articles

Effects of Fuel Aging on the Combustion Performance and Emissions of a Pyrolysis Liquid Biofuel and Ethanol Blend in a Swirl Burner

Pyrolysis liquid biofuel (also called bio-oil or pyrolysis oil) is a promising renewable fuel for stationary heat and power generation; however, the fuel properties, combustion performance, and combustion emissions degrade with fuel aging. The aging effects of softwood bark pyrolysis liquid biofuel on fuel properties and combustion performance are studied. To investigate the aging effects on fuel properties, the solid content, viscosity, estimated Sauter mean diameter (SMD), and thermogravimetric analysis (TGA) residue of pure pyrolysis liquid are considered. Furthermore, the CO emission, unburned hydrocarbon (UHC), and organic fraction of particulate matter (PM) emissions [also called carbonaceous residue (CR)] from combustion of the aged pyrolysis liquid biofuel/ethanol blend are measured to investigate the effect of aging on the combustion performance in a swirl spray burner. All measurements are employed for two batches of pyrolysis liquid biofuel with two levels of solid content. Results show that fu...

PCDDs, PCDFs and PCNs in products of microwave-assisted pyrolysis of woody biomass--Distribution among solid, liquid and gaseous phases and effects of material composition.

Microwave-assisted pyrolysis (MAP) of lignocellulosic biomass is a technique that could potentially be used to produce and upgrade renewable energy carriers. However, there is no available information about the formation of dioxins and other organic pollutants in MAP treatment of woody biomass. In this study, MAP experiments were conducted in lab-scale using virgin softwood, bark, and impregnated wood as feedstocks. The non-condensable gas, liquid (fractionated into aqueous and oil phases), and char fractions generated during pyrolysis were collected and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs). The concentrations of PCDDs, PCDFs and PCNs in the pyrolysis products ranged from 0.52 to 43.7 ng kg(-1). All investigated compound groups were most abundant in the oil fraction, accounting for up to 68% (w/w) of the total concentrations. The highest PCDD, PCDF and PCN concentrations were found from the pyrolysis of bark, which has relatively high contents of chlorine and mineral matter, followed by impregnated wood, which contains organic and metal-based preservatives. The homologue profiles of all three compound groups were dominated by the less chlorinated homologues. The homologue abundance decreased as the degree of chlorination increased. This trend was observed for all three feedstocks.

Production of porous carbon materials from bark

The effect of the conditions of consecutive carbonization–activation of the bark of larch, fir tree, and birch in a fluidized bed reactor on the yield, textural characteristics, and sorption properties of the resulting porous carbon materials was studied. The rate of temperature increase at the stage of the pyrolysis of bark exerted the greatest effect on the specific surface area, total pore volume, and sorption capacity of porous carbon materials for iodine and methylene blue. The porous carbon materials obtained by the slow pyrolysis (5 K/min) of larch bark with an isothermal exposure for 60 min at 600°C and the subsequent activation with CO2 at 850°C for 30 min were characterized by a maximum sorption activity. The porous carbon materials obtained from bark by consecutive carbonization–activation in a fluidized bed were similar to commercial powder sorbents from wood in their characteristics.

Differences in Bed Agglomeration Behavior during the Fast Pyrolysis of Mallee Bark, Leaf, and Wood in a Fluidized-Bed Reactor at 500 °C

This paper reports the significant differences in bed agglomeration behavior during the fast pyrolysis of various mallee biomass components (leaf, wood, and bark) in a fluidized-bed reactor at 500 °C. The pyrolysis of mallee leaf and bark led to significant bed agglomeration yields of 12.0 and 13.4%, respectively, while the pyrolysis of the wood component results in little bed agglomeration yield of <0.1%. Ethanol washing of the leaf and bark samples was carried out to prepare solvent-extracted leaf and bark samples (the solid residues after extraction) and the extract samples (obtained after evaporating the solvent from the extracted solvent solutions). Subsequent pyrolysis of the solvent-extracted leaf and bark samples showed drastically reduced bed agglomeration yields of 6.0 and 1.3%, respectively. Direct pyrolysis of the extract samples from leaf and bark resulted in substantial bed agglomeration yields of 24.4 and 34.1%, respectively, suggesting that the extractives within biomass play a critical role in the bed agglomeration during biomass fast pyrolysis. The experimental results indicate that, if the biomass from the whole mallee tree is used as a feedstock for bio-oil production via fluidized-bed fast pyrolysis, then the leaf and bark components are expected to cause bed agglomeration, because of the substantial amount of extractives present in these biomass materials.

Heat Transfer Model of Larch Bark Particles Pyrolysis

A novel model for larch bark pyrolysis was established by combine dimensions, shapes, boundary conditions, pyrolysis gas diffusion, particle size and reaction heat expression. It overcomes the shortages of early models which are short of expression of the reaction heat and application conditions. By introducing the kinetic equations and shape factor, the model was simulated by commercial software. The simulation results indicated that the pyrolysis time of particles is increasing by particle size, the best size for larch pyrolysis is 0.8 mm under 775K.

Organic compounds leached from fast pyrolysis mallee leaf and bark biochars

Characterization of organic compounds leached from biochars is essential in assessing the possible toxicity of the biochar to the soils’ biota. In this study the nature of the leached organic compounds from Mallee biochars, produced from pyrolysis of Mallee leaf and bark in a fluidised-bed pyrolyser at 400 and 580°C was investigated. Light bio-oil compounds and aromatic organic compounds were investigated. The ‘bio-oil like’ light compounds from leaf and bark biochars ’surfaces were obtained after leaching the chars with a solvent, suitable to dissolve the respective bio-oils. GC/MS was implemented to investigate the leachates. Phenolics, which are potentially harmful toxins, were detected and their concentration shown to be dependent on the char’s origin and the char production temperature. Further, to simulate biochars amendment to soils, the chars were leached with water. The water-leached aromatic compounds from leaf and bark biochars were characterized using UV-fluorescence spectroscopy. Those results suggested that biochars contain leachable compounds of which the nature and amount is dependent on the biomass feedstock, pyrolysis temperature and leaching time.

Fractional condensation of bio-oil vapors produced from birch bark pyrolysis

The bio-oil vapors produced from the pyrolysis of birch bark have been fractionated using a series of three condensers maintained at different temperatures. The temperatures of the condensers have been optimized in order to separate the water present in the bio-oil vapor stream from the organic phases and, consequently, increase the quality and the stability of the bio-oil. The condenser train consisted of an electrostatic precipitator-cum-condenser (C–ESP) installed between two cyclonic condensers. As a result of the high efficiency of the fractional condensation system, the water content of the fractionated bio-oil was reduced to be less than 1wt%. The effect of pyrolysis temperature on the fractionated bio-oil yield and characteristics is also reported.

Autothermal fast pyrolysis of birch bark with partial oxidation in a fluidized bed reactor

Fast pyrolysis of birch bark sawdust with partial (air) oxidation was studied in a bubbling fluidized bed reactor at reaction temperatures of 500 and 550°C. The bio-oil vapors were fractionated using a series of three condensers maintained at desired temperatures, providing a dry bio-oil with less than 1wt.% water and over 93% of the total bio-oil energy.Oxygen feed was varied to study its effect on yield, composition, and energy recovery in the gas, char and oil products. The addition of oxygen to the pyrolysis process increased the production of gases such as CO and CO2. It also changed the dry bio-oil properties, reducing its heating value, increasing its oxygen content, reducing its average molecular weight and its concentration of heavy bio-oil compounds, while increasing its viscosity and its phenolics concentration. The lower reaction temperature of 500°C was preferred for both dry bio-oil yield and quality.Autothermal operation of the pyrolysis process was achieved with an oxygen feed of 0.08g per g of biomass at the reaction temperatures of 500 and 550°C. At these two temperatures, when compared with the standard pyrolysis with pure nitrogen, the yield of dry bio-oil was reduced by 22% and 31%, whereas the total energy content of the dry bio-oil was reduced by 25% and 34%, respectively.

Characteristics of palm bark pyrolysis experiment oriented by central composite rotatable design

The rotatable design was applied for directing pyrolysis experiment of palm bark with the variation of retention time and reaction temperature. Based on the regression equations, the optimal operating conditions were extrapolated at 13.2 min, 459 °C and 15.7 min, 475 °C. The gas product comprised mainly C1–C4 hydrocarbons with the content up to 58.2 wt% while the liquid product was a complex mixture composed of mostly oxygenated compounds. Owing to using the high pressure condition as in tubing reactor, the reaction characteristics were different from those at normal pressure, thus possibly resulting in the high selectivity for liquid product. The analysis result of solid residue after reaction showed that the oxygen content was decreased noticeably to 25.4 wt% as compared to that of raw biomass due to pyrolysis.

Pyrolysis Features of Larch Bark and Xylem

In this paper, the ultimate, proximate and component analyses of the Daxinganling larch bark and xylem were performed and intercompared respectively. The pyrolysis features of the bark and xylem were analyzed by using the differential thermal thermo-gravimetric analyzer (TG). The influences of heating rate on pyrolysis features were discussed. The results show: (i) the content of H is a little more in the xylem than the bark and the content of ash in the bark is two times of the xylem and the content of fixed carbon in the xylem is two times of the bark. The content of alcohol-benzene extract is significantly more in the bark than the xylem and the glarson lignin in the bark is two times of the xylem but the hemicellulose in the xylem is three times of the bark; (ii) the process of the bark pyrolysis has two pyrolysis areas, but the xylem has a only pyrolysis area, however, the main pyrolysis interval of temperature of the bark and xylem are between 420K to 720K, in which the weight-loss of bark is 87-91% of the full weight-loss and the xylem weight-loss is 91-95% of the full weight-loss. (iii) the DTG peak of the xylem is behind 25 K of bark, and the DTG peak of the bark is-0.47 but the xylem-0.93. (iv) the curves of the TG and DTG move to the side of the higher temperature a bit following the heating rate increased, while the main pyrolysis areas are wider.

Catalytic reforming of tar during gasification. Part V. Decomposition of NOx precursors on the char-supported iron catalyst

A char-supported iron catalyst was investigated as a catalyst for destructing the NOx precursors (e.g. HCN and NH3) during the catalytic steam reforming of tar derived from the pyrolysis of mallee bark and leaf. It was found that the H-form char as a catalyst exhibited little activity for destructing NOx precursors even at high temperature, while on the contrary NOx precursors were decomposed efficiently on the char-supported iron catalyst during the steam reforming process. The activities of the char-supported iron catalyst for decomposing NOx precursors were indifferent for the gasification of bark and leaf. More importantly, the hydrolysis of HCN and the decomposition of NH3 are consecutive reactions during the catalytic steam reforming of biomass tar/volatiles. A majority of HCN was hydrolysed and converted to NH3 on the char-supported iron catalyst, where NH3 can be further decomposed to N2 when it has enough contact time with the catalyst during the steam reforming process.

Catalytic decomposition of toluene using a biomass derived catalyst

Pine bark biochar generated by slow pyrolysis (950°C) was used as a low cost catalyst to decompose toluene (model tar compound) over a temperature range of 600–900°C. Relative to thermal cracking, fractional toluene conversion increased from 13 to 94% when increasing temperatures from 600 to 900°C (2500ppmv, SV=0.76s−1, 3.8g catalyst) and Arrhenius analysis indicated an activation energy of 91kJ/mol, comparable to that of synthetic catalysts (e.g., 80.24kJ/mol for Ni/Mayenite and 196kJ/mol for olivine) and lower than that of thermal cracking (356kJ/mol). The reaction rate for toluene decomposition increased linearly from 550 to 700°C with a concentration range of 1000–4600ppmv indicating a first order rate law with respect to toluene. Benzene was detected as a potential intermediate in the decomposition of toluene with selectivity ranging from 0 to 28% at temperatures from 600 to 900°C respectively, and its formation increased with increasing toluene conversion. Toluene conversion ranged between 40 and 95% with benzene selectivity from 0 to 20% at 800°C during catalyst longevity studies of 6days. These results indicate that biochar generated from slow pyrolysis of pine bark at high temperature can be used as a low cost catalyst for tar removal from syngas. However, the tar removal rates using the biochar catalyst were lower than that of olivine and nickel based catalysts indicating the need to increase catalytic activity.

Influence of alcohol addition on properties of bio-oil produced from fast pyrolysis of eucalyptus bark in a free-fall reactor

Fast pyrolysis of eucalyptus bark was carried out in a free-fall pyrolysis unit at different temperatures ranging from 400 to 550°C to produce bio-oil, char and gas. The bio-oil produced at optimum temperature was mixed with alcohols with an aim to improve its properties. The results showed that the maximum bio-oil yield of 64.65wt% on dry biomass basis could be obtained at the pyrolysis temperature of 500°C. The addition of a small proportion (2.5–10%) of alcohol into the bio-oil could improve its viscosity, stability and heating value. These effects were further enhanced when increasing the alcohol.

Release of Chlorine during Mallee Bark Pyrolysis

Mallee bark (75–150 μm) was pyrolyzed at 400–900 °C under various conditions to investigate chlorine (Cl) release and distribution among char, tar, and gas. All Cl species in the bark are in form of water-soluble chlorides. In a fixed-bed pyrolysis reactor, the release of Cl is insensitive to pyrolysis temperature between 400 and 900 °C, with Cl completely released with volatiles (∼77% in tar and ∼23% in gas). In a drop-tube/fixed-bed reactor, under continuous feeding, the amount of Cl released at 400 °C is similar to that in the fixed-bed reactor. However, Cl retention in char increases with temperature, reaching a maximum at 600 °C (∼42%), and then decreases with further temperature increases (e.g., only ∼6% at 900 °C). In the same drop-tube/fixed-bed reactor under pulsed feeding conditions, Cl release and distribution follow similar trends but to a lesser extent. The results confirm that volatile–char interactions also play important roles in Cl release and distribution among products during biomass pyrolysis and that Cl in char is thermally unstable at elevated temperatures. Calculations by difference further suggest that substantial Cl (47–84%) is present in tars. Quantification of Cl in tar was then carried out experimentally via in situ combustion of biomass volatiles produced using a two-column pyrolysis/combustion reactor. The results confirm the presence of substantial organically bounded Cl in tar. The mass balances of Cl in char, tar, and gas achieve ∼100% closure during biomass pyrolysis in the fixed-bed reactor between 400 and 900 °C, as well as that during biomass pyrolysis in the drop-tube/fixed-bed reactor below 600 °C. However, at temperatures >600 °C, 100% Cl mass balance cannot be achieved during in situ combustion of volatiles and the data suggest that some Cl react with inorganic species (e.g., Na and K) in the gaseous phase to form alkali chlorides, which are deposited on the reactor wall.

Effects of temperature on the yields and properties of bio-oil from the fast pyrolysis of mallee bark

Bark constitutes an important part of any woody biomass to be used for the production of second generation biofuels and chemicals. Pyrolysis followed by biorefinery is a promising technology for the efficient utilisation of all components from a woody crop. While significant efforts have been devoted to the investigation of the pyrolysis characteristics of wood, relatively less is known about the pyrolysis behaviour of bark. This study aims to clarify the effects of temperature on the yields and composition of bio-oil from the pyrolysis of eucalypts bark. The bark of mallee, a type of eucalypt grown for soil amendment in Western Australia, was pyrolysed between 300 and 580°C at fast heating rates in a fluidised-bed pyrolysis unit. The bio-oil liquid products separate into two phases. The bio-oil liquid products were analysed by GC–MS, Karl-Fischer titration, UV-fluorescence spectroscopy, ICP-OES and thermogravimetric analysis (TGA). These results are compared, when appropriate, to those obtained from the wood fraction.

Comparison between the “one-step” and “two-step” catalytic pyrolysis of pine bark

In this study, one-step and two-step pyrolysis systems were compared in the pyrolysis of pine bark. One-step pyrolysis was performed in a fixed bed reactor with and without catalyst. Two-step pyrolysis was carried out in a dual reactor system over catalyst; the first reactor containing no catalyst whereas the second reactor containing catalyst to upgrade the thermally cracked products. The catalysts used in the pyrolysis systems were ReUS-Y, red mud and ZSM-5. In thermal pyrolysis, the pyrolysis system mainly affected the relative amount of bio-oil. The bio-oil yields obtained from two-step thermal pyrolysis were higher than the yields from one-step thermal pyrolysis. In the catalytic runs, ReUS-Y catalyst slightly decreased the char formation with a consequent increase in aqueous phase yield in the case of one-step pyrolysis. However, the catalysts decreased the bio-oil yield with a consequent increase in the gas yield in the case of two-step pyrolysis. The general compositions of bio-oils obtained from both two pyrolysis systems were affected by using catalysts. In the case of one-step pyrolysis, the formation of water and water soluble compounds were reduced by using ReUS-Y catalyst. In the case of two-step pyrolysis, both ZSM-5 and red mud increased the formation of water soluble compounds while they decreased water formation. In contrast, ReUS-Y decreased the formation of water soluble compounds and increased the amount of pyrolytic lignin compounds in bio-oil. Fuel characteristics of pyrolysis products (gas, bio-oil and char) for both two pyrolysis systems were also investigated comparatively.

Compositional Characterization and Pyrolysis of Loblolly Pine and Douglas-fir Bark

Two potential biofuel resources, Douglas-fir and Loblolly pine bark, were subjected to extensive chemical and compositional analysis. The barks were initially extracted with dichloromethane, and the resulting extracted compounds were characterized by gas chromatography coupled with mass spectrometric analysis. Characterization of the major bark biocomponents indicated that Douglas-fir and Loblolly pine bark contained 22.5 and 13.2 % tannins, 44.2 and 43.5 % lignin, 16.5 and 23.1 % cellulose, and 7.6 and 14.1 % hemicellulose, respectively. Of particular interest is the high content of tannins and lignin, which make these barks excellent potential precursors for bio-oils and/or other value-added chemicals. 13C nuclear magnetic resonance (NMR) was used to characterize the chemical structure of the lignin and tannins. These samples were also analyzed by 31P NMR after phosphitylation of the hydroxyl groups in lignin and tannins. The NMR spectral data indicated that the lignin in both barks contained p-hydroxyphenyl (h) and guaiacyl (g) of lignin monomers with an h/g ratio of 10:90 and 22:78 for Douglas-fir and Loblolly pine bark, respectively. Gel permeation chromatography was used to analyze the molecular weight distributions of extracted tannins, isolated cellulose, and ball-milled lignin. The pyrolysis of Douglas-fir and pine bark at 500°C in a tubular reactor generated 48.2 and 45.2 % of total oil, of which the light oil contents are 14.1 and 20.7 % and heavy oil are 34.1 and 24.4 %. Similarly, fast pyrolysis at 375°C yielded 56.1 and 49.8 % of total oil for Douglas-fir and pine bark, respectively.

Acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark

This paper reports the acid-catalysed reactions between methanol and the bio-oil from the fast pyrolysis of mallee bark. The study focused on the reactions of the fatty acids, esters, furans and anhydrosugars in the bio-oil with methanol at 70–170°C in the presence of a solid acid catalyst Amberlyst 70. Under the experimental conditions employed, both simple acids and fatty acids in bio-oil could be converted to either methyl esters or lactone, respectively. High molar mass esters in the original bio-oil tend to undergo transesterification to produce methyl esters. Furan aldehydes such as furfural and 5-methyl-2-furancarboxaldehyde mainly underwent acetalisation to their acetals, while 5-(hydroxymethyl)furfural (HMF) could undergo acetalisation and/or etherification. HMF including its ethers and acetals could be further converted into methyl levulinate at elevated temperatures. In addition, methyl levulinate was also found to be the product from the methanolysis of other furans such as 2-furylmethanol and the C6 anhydrosugars in bio-oil.

Biochar as a Fuel: 4. Emission Behavior and Characteristics of PM1 and PM10 from the Combustion of Pulverized Biochar in a Drop-Tube Furnace

Six biochar samples were produced from both slow and fast pyrolysis of mallee bark at 400–550 °C, respectively; such temperatures are typically used for biochar and/or bio-oil production in practice. Under the pyrolysis conditions, the biochar yields range from 26.7 to 37.0% and the majority (78.5–100.0%) of alkali and alkaline earth metallic (AAEM) species (mainly Na, K, Mg, and Ca) in biomass are retained in the biochars, while the retention of Cl in biochars is only 2.0–33.4%. The raw biomass and its derived biochar samples were then combusted in a laboratory-scale drop-tube furnace (DTF) at 1300 °C to investigate the emission behavior and characteristics of sub-micrometer particulate matter (PM1) and PM with an aerodynamic diameter less than 10.0 μm (PM10). The particle size distribution (PSD) of PM10 from raw biomass combustion has a bimodal size distribution, while the PSDs of PM10 from biochar combustion generally show a unimodal distribution. Although most inorganic species are retained in the biochar during pyrolysis, it is interesting to note that the combustion of biochars leads to a substantial reduction in the emission of PM1 (and the mass of Na, K, and Cl in PM1) that dominantly consists of PM with a size less than 0.1 μm (PM0.1) in comparison to biomass combustion, apparently because of the removal of volatiles and Cl from the raw biomass during pyrolysis for biochar preparation. The results imply that the combustion of volatiles (including the released inorganic species), which is particularly important during biomass combustion, is mainly responsible for PM1 emission. Meanwhile, considerable increases in the emission of coarser particulate matter with an aerodynamic diameter between 1 and 10 μm (PM1−10) and the mass of Mg and Ca in PM1−10 are also evident during biochar combustion, most likely as a result of more porous structure and increased ash loading of biochars.

Influence of Inorganic Additives on Pyrolysis of Pine Bark

This paper investigated the effect of inorganic additives on pine bark pyrolysis using a thermogravimetry instrument. Both thermogravimetry (TG) and differential thermogravimetry (DTG) were performed to a final temperature of 600 °C with heating rates of 10, 20, and 50 °C/min, respectively, and a nitrogen flow rate of 50 mL/min. Six types of inorganic additives at different loading were tested. The pyrolysis kinetics data of the samples were fitted to the Coats–Redfern model. The results showed that the pyrolysis behavior and kinetics are significantly altered by the additives and are a strong function of the characteristics and concentrations of the additives.