Rotary kiln pyrolysis of straw and fermentation residues in a 3 MW pilot plant – Influence of pyrolysis temperature on pyrolysis product performance

The idea of co-firing biomass in an already existing coal-fired power plant could play a major contribution in the reduction of carbon dioxide emissions. Huge amounts of unused biomass in terms of agricultural residues such as straw, which is a cheap and local feedstock, are often available. But due to the high amount of corrosive ash elements (K, Cl, etc.), the residues are usually not suitable for co-firing in a thermal power plant. Therefore, the feedstock is converted by low temperature pyrolysis into gaseous pyrolysis products and charcoal. A 3 MW pyrolysis pilot plant located next to a coal-fired power plant near Vienna was set up in 2008. For the process, an externally heated rotary kiln reactor with a design fuel power of 3 MW is used which can handle about 0.6–0.8 t/h straw. The aim is to investigate the fundamentals for scale-up to the desired size for co-firing in a coal-fired power plant. In addition to the desired fuel for the process, which is wheat straw, a testing series for DDGS was also performed. The high amount of pyrolysis oil in the gas had positive effects on the heating value of the pyrolysis gas. Chemical efficiencies of this pyrolysis pilot plant of up to 67% for pyrolysis temperatures between 450 °C and 600 °C can be reached. The focus of this work is set on the pyrolysis products and their behavior at different pyrolysis temperatures as well as the performance of the pyrolysis process.     

Study of products yield of bagasse and sawdust via slow pyrolysis and iron-catalyze

In this paper, the via slow pyrolysis behavior of the bagasse and sawdust were studied at the different heating rates, the different iron-containing blend pyrolysis and the treatment temperature, the further understood for the pyrolysis of agricultural residues. The distribution of the products yield of the slow pyrolysis process, it is typically performed at temperature between 200 and 600 °C, the pyrolysis temperature increased, the bio-liquids and gas yields tended to increase, which at 400 °C was able to achieve maximum bio-liquids yields, the biochar yields tended to downward. For different heating rate, in the heating rate ranges for 80–100 W, the bio-liquids products yield curve increased from 44.5 wt% to 46.5 wt% for bagasse; the sawdust products yield increased from 41 wt% to 42.75 wt%. Iron-catalysts blend pyrolysis (0, 10, 25, 40 and 50 wt%), the bagasse bio-liquid yields respectively 56.25 wt% in the presence 50% iron-catalysts blend pyrolysis; the sawdust bio-liquid yields respectively 52.5 wt% in the presence 40% iron-catalysts blend. The pyrolysis process were calculated according to the kinetic mechanism were examined, the pyrolysis activation energy was between 6.55 and 7.49 kcal/mol for bagasse. Sawdust the pyrolysis activation energy was between 11.52 and 11.76 kcal/mol. Therefore, in this study a pyrolysis model of bagasse and sawdust thermal treatment may provide both agricultural and forestry transformation importance of resources.     

Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl₂, AlCl₃) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.     

Catalytic pyrolysis of Phragmites (reed): Investigation of its potential as a biomass feedstock

In this paper, thermogravimetry, TG, and pyrolysis are used for the thermochemical evaluation of the common reed (Pragmites australis) as a candidate biomass feedstock. The TG analysis indicated that the material loses 4% of its weight below 150 °C through dehydration. The main decomposition reaction occurs between 200 and 390 °C. The rate of weight loss, represented by the derivative thermogravimetric, DTG, signal indicated a multi-step reaction. Kinetic analysis helped in the resolution of the temperature ranges of the overlapping steps. The first step corresponds to the degradation of the hemi-cellulosic fraction and the second to the cellulosic fraction degradation. The TG and DTG signals of reed samples treated with increasing concentration of potassium carbonate (0.6–10 wt%) indicated a catalytic effect of the salt on reed decomposition. The temperature of maximum weight loss rate, DTGmax, exponentially decreased with increasing catalyst content, whilst the initial temperature of the decomposition decreased linearly. The pyrolysis studies were carried out in a Pyrex vertical reactor with sintered glass disc to hold the sample and to aid the fluidization with the nitrogen stream flowing upwards. The reactor was connected to a cyclone and condenser and a gas sampling device. Tar and char are collected and weighed. The gas chromatographic analysis of the evolved gases demonstrated the effect of pyrolysis temperature (400, 450, and 500 °C) on their composition. The temperature increase favors the yields of hydrocarbons, carbon monoxide and hydrogen at the expense of methanol and carbon dioxide. Similarly, reed samples treated with K2CO3 at 10 wt% were pyrolyzed and analyzed. Comparisons for the various parameters (yields, gas composition and carbon–hydrogen recovery) between the untreated and catalyzed reed conversion were also made.     

Pyrolysis of cohesive meat and bone meal in a bubbling fluidized bed with an intermittent solid slug feeder

Meat and bone meal (MBM) is a mass-produced by-product of the meat rendering industry. It has great potential as a feedstock for the production of bio-fuels. Meat and bone meal, however, is a highly cohesive and temperature sensitive material and has traditionally been found to be very difficult, if not impossible, to feed properly into pyrolysis reactors or bubbling fluidized beds. This study showcases an application of the ICFAR intermittent solid slug feeder technology and its capability of successfully feeding the MBM regularly at an average feeding rate of 0.34 g/s into the reactor.A highly automated and instrumented fast pyrolysis pilot plant has been used to process meat and bone meal residues and to operate within a wide range of temperatures (450–600 °C). This is the first study dealing with the pyrolysis of pure meat and bone meal at various operating conditions continuously fed into a laboratory-scale fluidized bed reactor. All liquid and solid products have been analyzed (yields, HHV, GC–MS, elemental analysis, and ash mineral analysis). The homogenous bio-oil produced is an attractive fuel with a significant high heating value (HHV) of 31.5 MJ/kg and an average liquid yield of 43 wt% at 550 °C. The highest water-free HHV (36.7 MJ/kg) was found at 500 °C, with a liquid yield of 35 wt% at this temperature. The optimized pyrolysis temperature, at which the heat from the gas combustion can provide the heat required for processing MBM, while maximizing the bio-oil liquid yield and process energy yield, is 550 °C. Under these conditions, the pyrolysis process energy yield is 91%.The study also demonstrates a new technique to accurately determine the heat of pyrolysis reaction energy required by the process, using a non-invasive water calibration method.     

Sub-critical water extraction of bitumen from Huadian oil shale lumps

Three sizes of Huadian oil shale lumps from 1 cm to 10 cm were extracted by sub-critical water at 350 °C and 16 MPa for 2–70 h. The oil shale lumps were fractured alone the shale texture in sub-critical water that greatly improved the extraction efficiency of bitumen from the large- and middle-sized sample. The extract yields of bitumen from different sized samples were similar when the extraction time is longer than 20 h and stabilized at about 18 wt.% (ad) after 50 h duration. With the increase of extraction time, asphaltene and preasphaltene extracts were gradually decomposed to maltene. The gas chromatography–mass spectrometry (GC–MS) analysis of the extracts showed that n-alkanes, n-alk-1-enes, isoprenoids, n-alk-2-ones and n-alkanoic acids were the major components. In contrast, aromatic extracts were rare and most of them were remained in the shale residue. The pyrolysis gas chromatography–mass spectrometry (Py-GC–MS) analysis of the spent shale showed that the final undecomposed organics in kerogen were some macromolecular linear hydrocarbon, n-alk-2-ones and n-alkanoic acids fragments. The comparison of the classical pyrolyzate and the sub-critical water extracts showed that the water extracts contained more long-chain alkanes than anhydrous pyrolysis and the alkene extracts could transform to alkanes in sub-critical water. Moreover, the n-alkanoic acids could be decomposed to short-chain compounds through the cleavage of carbon carbon bonds.     

Characterization of slow pyrolysis oil obtained from linseed (Linum usitatissimum L.)

This study presents the characterization of pyrolysis oil obtained from linseed (Linum usitatissimum L.) produced by slow pyrolysis in the maximum yield. The pyrolysis oil was analyzed to determine its elemental composition and calorific value. The chemical composition of the pyrolysis oil and fractions were investigated using chromatographic and spectroscopic techniques (¹H NMR, IR, and GC). The chemical class composition of the oil was determined by liquid column chromatographic fractionation. The oil was separated into pentane soluble and insoluble fractions by using pentane. The column was eluted successively with n-pentane, toluene and methanol to yield aliphatic, aromatic and polar fractions, respectively. The results of the adsorption chromatography of the oil showed that the pyrolysis oil consists of 88 wt% n-pentane soluble. The aliphatic, aromatic and polar fractions of oils obtained in slow pyrolysis are 30, 34, 36 wt%, respectively. The aliphatic and aromatic subtraction make up ∼64 wt% in slow pyrolysis oil. This seems to be more appropriate for the production of hydrocarbons and chemicals.     

Production of bio-oil via fast pyrolysis of agricultural residues from cassava plantations in a fluidised-bed reactor with a hot vapour filtration unit

This article reports experimental results on fast pyrolysis of agricultural residues from cassava plantations, namely cassava rhizome (CR) and cassava stalk (CS), in a fluidised-bed fast pyrolysis reactor unit incorporated with a hot vapour filter. The objective of this research was to investigate the effects of reaction temperatures, biomass particle size and the use of simple hot vapour filtration on pyrolysis product yields and properties. Results showed that the optimum pyrolysis temperatures for CR and CS were 475 °C and 469 °C, which gave maximum bio-oil yields of 69.1 wt% and 61.4 wt% on dry biomass basis, respectively. The optimum particle size for bio-oil production in this study was 250–425 μm. The use of the hot filter led to a reduction of 6–7 wt% of bio-oil yield. Nevertheless, the filtered bio-oils appeared to have a better quality in terms of initial viscosity, solids content, ash content and stability.     

Characterization of the different fractions obtained from the pyrolysis of rope industry waste

A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250 °C, with the main region of decomposition occurring at temperatures between 300 and 350 °C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22 wt.% of a carbonaceous residue, 50 wt.% tars and a gas fraction at 800 °C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400 °C, there are some pyrolytic reactions still going on above 550 °C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO₂, CO and CH₄. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.     

Copyrolysis of scrap tires with oily wastes

In this study, the conversion of hazardous wastes into liquid fuels was investigated. The pyrolysis of bilge water oil and oil sludge from ships, scrap tires and their blends was carried out at 400 and 500 °C in absence and presence of catalyst. A commercial fluid catalytic cracking catalyst and Red Mud were used as catalyst. Pyrolysis products were separated as gas, oil and char. The pyrolytic oils were characterized by using gas chromatography-mass selective detector (GC-MSD) and ¹H nuclear magnetic resonance (¹H-NMR). The effect of temperature and catalyst on the product distribution and the composition of oil from pyrolysis were investigated. Co-pyrolysis of scrap tire with oily wastes from ships produced oil that could be used as fuel, while its pyrolysis alone produced oil that could be used as a chemical feedstock. The results obtained in this study showed that co-pyrolysis of oily wastes with scrap tires could be an environmentally friendly way for the transformation of hazardous wastes into valuable products such as chemicals or fuels.     

Influence of FCC catalyst steaming on HDPE pyrolysis product distribution

A commercial FCC catalyst based on a zeolite active phase has been used in the catalytic pyrolysis of HDPE. The experimental runs have been carried out in a conical spouted bed reactor provided with a feeding system for continuous operation. Different treatments have been applied to the catalyst to improve its behaviour. This paper deals with the optimization of catalyst steaming and pyrolysis temperature in order to maximize the production of diesel-oil fraction. The performance of the fresh catalyst has been firstly studied at 500 °C. This catalyst gives way to 52 wt% gas yield, 35 wt% light liquid fraction and a low yield of C₁₀⁺ fraction (13 wt%). After mild steaming (5 h at 760 °C) the results show a significant improvement in product distribution. Thus, gas yield decreases to 22 wt%, the yield of light liquid is similar to that of the fresh one (38 wt%), whereas the yield of the desired C₁₀⁺ fraction increases to 38 wt%. Nevertheless, the best results have been obtained when a severe steaming is applied to the catalyst (8 h at 816 °C) and pyrolysis temperature is reduced to 475 °C. There is a significant reduction in the gaseous fraction (8 wt%). The light liquid fraction has also been reduced to 22 wt%, but the yield of diesel fraction increases to 69 wt%. Moreover, the deactivation of the catalyst has also been studied under the optimum conditions.     

Conventional and microwave induced pyrolysis of coffee hulls for the production of a hydrogen rich fuel gas

This paper describes the conventional and microwave-assisted pyrolysis of coffee hulls at 500, 800 and 1000 °C. The influence of the pyrolysis method and temperature on the product yields and on the characteristics of the pyrolysis products is discussed. It was found that the pyrolysis of this particular residue gives rise to a larger yield of the gas fraction compared to the other fractions, even at relatively low temperatures. A comparison of microwave-assisted pyrolysis and conventional pyrolysis showed that microwave treatment produces more gas and less oil than conventional pyrolysis. In addition, the gas from the microwave has much higher H₂ and syngas (H₂ + CO) contents (up to 40 and 72 vol.%, respectively) than those obtained by conventional pyrolysis (up to 30 and 53 vol.%, respectively), in an electric furnace, at similar temperatures. From the pyrolysis fraction yields and their higher heating values it was found that the energy distribution in the pyrolysis products decreases as follows: gas > solid > oil. Moreover, the energy accumulated in the gas increases with the pyrolysis temperature. By contrast, the energy accumulated in the char decreases with the temperature. This effect is enhanced when microwave pyrolysis is used.     

Biomass pyrolysis: Kinetic modelling and experimental validation under high temperature and flash heating rate conditions

This work analyzes and discusses the general features of biomass pyrolysis, both on the basis of a new set of experiments and by using a detailed kinetic model of biomass devolatilization that includes also successive gas phase reactions of the released species and is therefore able to predict the main gases composition. Experiments are performed in a lab-scale Entrained Flow Reactor (EFR) to investigate biomass pyrolysis under high temperatures (1073–1273 K) and high heating fluxes (10–100 kW m⁻²). The influence of particle dimensions and temperature has been tested versus solid residence time in the reactor. The particle size appeared as the most crucial parameter. The pyrolysis of 0.4 mm particles is nearly finished under this range of temperatures after a reactor length of 0.3 m, with more than 75 wt% of gas release, whereas the conversion is still under evolution until the end of the reactor for larger particles up to 1.1 mm, due to internal heat transfer limitations. The preliminary comparisons between the model and the experimental data are encouraging and show the ability of this model to contribute to a better design and understanding of biomass pyrolysis process under severe conditions of temperature and heating fluxes typically found in industrial gasifiers.     

Pyrolysis of textile wastes: I. Kinetics and yields

Thermal behavior of textile waste was studied by thermogravimetry at different heating rates and also by semi-batch pyrolysis. It was shown that the onset temperature of mass loss is within 104–156 °C and the final reaction temperature is within 423–500 °C. The average mass loss is 89.5%. There are three DTG peaks located at the temperature ranges of 135–309, 276–394 and 374–500 °C, respectively. The first two might be associated with either with decomposition of the hemicellulose and cellulose or with different processes of cellulose decomposition. The third peak is possibly associated to a synthetic polymer. At a temperature of 460 °C, the expected amount of volatiles of this waste is within 85–89%. The kinetic parameters of the individual degradation processes were determined by using a parallel model. Their dependence on the heating rate was also established. The pyrolysis rate is considered as the sum of the three reaction rates. The pyrolysis in a batch reactor at 700 °C and nitrogen flow of 60 ml/min produces 72 wt.% of oil, 13.5 wt.% of gas and 12.5 wt.% of char. The kinetic parameters of the first peak do not vary with heating rate, while those of the second and the third peak increase and decrease, respectively, with an increasing heating rate, proving the existence of complex reaction mechanisms for both cases.     

Chemical characterization and phase behaviour of grape seed oil in compressed carbon dioxide and ethanol as co-solvent

The aim of this work is to report phase equilibrium experimental results for the systems grape oil/carbon dioxide and (grape oil/carbon dioxide + ethanol). The oil was obtained by supercritical extraction from the grape seed residue from wine production. The static synthetic method using a variable-volume view cell was employed for obtaining the experimental bubble and dew (cloud) points transition data over the temperature range of (313.15 to 343.15) K and pressures up to 20.6 MPa. The experiments were carried out using (ethanol + CO₂) overall mass fractions ranging from 0.50 to 0.99, keeping a fixed ethanol to carbon dioxide molar ratio at 1:3. Results indicate the existence of complex phase behaviour for all temperatures investigated with the occurrence of vapour–liquid, liquid–liquid and vapour–liquid–liquid phase transitions observed.     

Characterization of the water-insoluble pyrolytic cellulose from cellulose pyrolysis oil

Water-insoluble pyrolytic cellulose with similar appearance to pyrolytic lignin was found in cellulose fast pyrolysis oil. The influence of pyrolysis temperature on pyrolytic cellulose was studied in a temperature range of 300–600 °C. The yield of the pyrolytic cellulose increased with temperature rising. The pyrolytic cellulose was characterized by various methods. The molecular weight distribution of pyrolytic cellulose was analyzed by gel permeation chromatography (GPC). Four molecular weight ranges were observed, and the M_w of the pyrolytic cellulose varied from 3.4 × 10³ to 1.93 × 10⁵ g/mol. According to the elemental analysis (EA), the pyrolytic cellulose possessed higher carbon content and lower oxygen content than cellulose. Thermogravimetric analysis (TGA) indicated that the pyrolytic cellulose underwent thermo-degradation at 127–800 °C and three mass loss peaks were observed. Detected by the pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), the main pyrolysis products of the pyrolytic cellulose included saccharides, ketones, acids, furans and others. Fourier transforms infrared spectroscopy (FTIR) also demonstrated that the pyrolytic cellulose had peaks assigned to CO stretching and glycosidic bond, which agreed well with the Py-GC/MS results. The pyrolytic cellulose could be a mixture of saccharides, ketones, and their derivatives.     

H2 enriched fuels from co-pyrolysis of crude glycerol with biomass

Pyrolysis of glycerol has been identified as a possible route for producing high added value fuels like renewable hydrogen (H₂). Crude glycerol (CG) is the main byproduct of biodiesel industry and without purification it is a low added value material due to the presence of impurities. Co-pyrolysis of CG with biomass may improve the efficiency of the process and as a primary step of gasification give important information concerning the maximization of H₂ concentration in the produced gas. Moreover, the thermochemical treatment of crude glycerol–biomass mixtures may offer several economic and environmental advantages in biodiesel industry and reduce the cost of biodiesel production. A mixture of CG with olive kernel (OK) was used as pyrolysis feed material. Pyrolysis of a 25 wt% mixture of CG with OK at high temperature (T = 720 °C) seemed to promote steam reforming reactions leading to an increase of H₂ concentration of 11.6 vv% in the pyrolysis gas in comparison to H₂ in gas obtained by low temperature pyrolysis (T = 520 °C).     

(Vapour + liquid) equilibria of the {1,1,1-trifluoroethane (HFC-143a) + isobutene} system

Isothermal (vapour + liquid) equilibrium data were measured for the {1,1,1-trifluoroethane (HFC-143a) + isobutene} as an alternative refrigerant in the temperature range from (273.15 to 348.15) K at 15 K intervals. A circulating-type apparatus with on-line gas chromatography was used in these experiments. The experimental data were correlated well by Peng–Robinson equation of state using the Wong–Sandler mixing rules.     

Pyrolytic behavior of cellulose in presence of montmorillonite K10 as catalyst

Cellulose and cellulose/montmorillonite K10 mixtures of different ratio (9:1, 3:1, 1:1) were subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 46–73.5 wt% depending on the temperature, the heating rate and the amount of catalyst. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil (84 wt%). The blending cellulose with increasing amount of montmorillonite K10 results in significant, linear decrease in bio-oil yield. The great influence of montmorillonite K10 amount on the distribution of bio-oil components was observed at 450 °C with a heating rate of 100 °C/s. The addition of catalyst to cellulose promotes the formation of 2-furfural (FF), various furan derivatives, levoglucosenone (LGO) and (1R,5S)-1-hydroxy-3,6-dioxabicyclo-[3.2.1]octan-2-one (LAC). Simultaneously, the share of levoglucosan (LG) in bio-oil decreases from 6.92 wt% and is less than 1 wt% when cellulose:MK10 (1:1, w/w) mixture at 450 °C is rapidly pyrolyzed. Additionally, several other compounds have been identified but in minor quantities. Their contributions in bio-oil also depend on the amount of catalyst.     

Phase behaviour of heavy petroleum fractions in pure propane and n-butane and with methanol as co-solvent

This work reports phase equilibrium experimental results for heavy petroleum fractions in pure propane and n-butane as primary solvents and using methanol as co-solvent. Three kinds of oils were investigated from Marlim petroleum: a relatively light fraction coming from the first distillation of crude petroleum at atmospheric pressure (GOP – heavy gas oil of petroleum), the residue of such distillation (RAT) and the crude petroleum sample. Phase equilibrium measurements were performed in a high-pressure, variable-volume view cell, following the static synthetic method, over the temperature range of 323 K to 393 K, pressures up to 10 MPa and overall compositions of heavy component varying from 1 wt% to 40 wt%. Transition pressures for low methanol and oil concentrations were very close for GOP, RAT, and crude Marlim when using propane as the primary solvent. Close to propane critical temperature, two and three-phase transitions were observed for GOP and Marlim when methanol was increased. When n-butane was used as primary solvent, all transitions observed were of (vapour + liquid) type with transition pressure values smaller than those obtained for propane.