Fast Pyrolysis Reactor Research Articles

Stepwise isothermal fast pyrolysis (SIFP) of biomass. Part 1. SIFP of pine sawdust

Pyrolysis of pine wood sawdust was carried out using stepwise isothermal fast pyrolysis (SIFP), focusing on the search of reaction conditions to obtain chemicals in good yields from biomass. SIFP consists of successive isothermal fast pyrolysis reactions, where solid products obtained in the previous isothermal fast pyrolysis become the substrate of the subsequent reaction at a higher temperature. This article reports results obtained by SIFP of pine sawdust between 200 and 600°C using 100°C intervals under vacuum (0.2 mm), using nitrogen as carrier gas. Both sets of reactions made it possible to obtain most of the compounds that have been previously described in conventional fast pyrolysis experiments; however this system produces a smaller number of chemical compounds in each isothermal FP, making it easier to obtain determined chemicals with industrial or research value. Maximum yield of liquid products occurred at 300°C, giving around 30% of bio-oil, which contained mainly phenols and furan derivatives. Liquid-Liquid extraction led to a rich mixture of phenol derivatives. Results showed that SIFP is an interesting technique to obtain enriched fractions of products derived from biomass pyrolysis.

Research on CFD of Fluidization of Biomass Waste Fast Pyrolysis Reactor

Biomass fast pyrolysis technology is one of most promising methods to utilize biomass resources, for its high production of pyrolysis liquid named bio-oil. And the fast pyrolysis fluidized reactor is widely used because of the advantages of simple structure, and easy to enlarge. The understanding of computational fluid dynamics (CFD) of its fluidized bed is necessary basis for particulate heat transfer and pyrolysis kinetics research. In this paper, modern hydrodynamic theory and calculation means is employed to simulate the cold state of fluid behavior in the pilot-scale fluidized pyrolysis reactor. The simulation results are in good agreement with the empirical equation and experimental data, with resultant error lower than 10%. Based on the cold state simulation, we modeled the fluid flow behavior in the fluidized reactor during fast pyrolysis under high temperature, and calculated the fluidization velocity and the distribution of solid phase fraction.

Process Optimization of Fast Pyrolysis Reactor for Converting Forestry Wastes into Bio-Oil with the Taguchi Method

Abstract A novel fast pyrolysis reactor for converting biomass (agriculture and forestry wastes) into bio-oil developed by the authors was used in this study. Taguchi experimental design method and the SPSS (Statistical Package for Social Sciences) multiple regression analysis software were employed to analyze the effects of some selected key process parameters, including the size of the feedstocks, the pyrolysis temperature and the feed rate (rotational speed of the screw extruder), on the maximum yield of the bio-oil produced from forestry wastes(camphor tree). The results show that the optimal operation conditions for attaining the highest yield of bio-oil (60.2%) are: 3.35 mm grain size - 40 rpm screw extruder rotational speed - 500 oC pyrolysis temperature. In addition, when larger grain sizes are used, higher feed rates are required to achieve peak bio-oil yields. As a result, a significant increase in productivity can be expected.

Characterization of Coconut Shell Activated Carbon Obtained from By-Product of Preparation Process of Bio-Oil with Fast Pyrolysis

A new process was investigated which combines both fast pyrolysis carbonization and CS activated carbons with H3PO4 activation (CSAC). ACs were obtained as by-product from the preparation process of bio-oil with fast pyrolysis under different temperatures (T=727–973 K), in which the reaction ended in a very short duration. A two-step process of reaction is proposed to govern carbonization and activation: firstly fast pyrolysis reaction removing disorganized material was associated with considerable weight loss but with low generation of porosity, pyrolysis/carbonization under the flow of N2 is suggested to ensure fluidization of CS powders and bed material, enhance decomposition of raw material, initiates controlled gasification at different temperatures. Then H3PO4 activation process dominated at 573 K, which leads to considerable evolution of porosity. In this research, the adsorption characteristics were determined from N2 adsorption isotherms and subsequent analysised by the BET-and BJH-methods. As a result, the iodine adsorption number of AC was 1310 mg/g and the SSA of AC was 1421.38 m2/g .

Lignin fast pyrolysis: Results from an international collaboration

An international study of fast pyrolysis of lignin was undertaken. Fourteen laboratories in eight different countries contributed. Two lignin samples were distributed to the laboratories for analysis and bench-scale process testing in fast pyrolysis. Analyses included proximate and ultimate analysis, thermogravimetric analysis, and analytical pyrolysis. The bench-scale test included bubbling fluidized-bed reactors and entrained-flow systems. Based on the results of the various analyses and tests it was concluded that a concentrated lignin (estimated at about 50% lignin and 50% cellulose) behaved like a typical biomass, producing a slightly reduced amount of a fairly typical bio-oil, while a purified lignin material was difficult to process in the fast pyrolysis reactors and produced a much lower amount of a different kind of bio-oil. It was concluded that for highly concentrated lignin feedstocks new reactor designs will be required other than the typical fluidized-bed fast pyrolysis systems.

Influence of inorganic salts on the primary pyrolysis products of cellulose

Processing bio-oil with the help of currently existing petroleum refinery infrastructure has been considered as a promising alternative to produce sustainable fuels in the future. The feasibility of bio-oil production and upgrading processes depend upon its chemical composition which in turn depends on the biomass composition and the process conditions of the fast pyrolysis reactions. The primary goal of this paper was to investigate the effect of mineral salts including mixtures of salts in the form of switchgrass ash on the chemical speciation resulting from primary pyrolysis reactions of cellulose and to gain an insight of the underlying mechanisms. Various concentrations of inorganic salts (NaCl, KCl, MgCl2, CaCl2, Ca(OH)2, Ca(NO3)2, CaCO3 and CaHPO4) and switchgrass ash were impregnated on pure cellulose. These samples were pyrolyzed in a micro-pyrolyzer connected to a GC–MS/FID system. Effects of minerals on the formation of (a) low molecular weight species – formic acid, glycolaldehyde and acetol, (b) furan ring derivatives – 2-furaldehyde and 5-hydroxy methyl furfural and (c) anhydro sugar – levoglucosan are reported exclusively. Further, the effect of reaction temperature ranging from 350 to 600°C on the pyrolysis speciation of pure and ash-doped cellulose is also reported. The pyrolysis speciation revealed the competitive nature of the primary reactions. Mineral salts and higher temperatures accelerated the reactions that led to the formation of low molecular weight species from cellulose as compared to those leading to anhydro sugars.

Effect of Temperature in Fluidized Bed Fast Pyrolysis of Biomass: Oil Quality Assessment in Test Units

Pine wood was pyrolyzed in a 1 kg/h fluidized bed fast pyrolysis reactor that allows a residence time of pine wood particles up to 25 min. The reactor temperature was varied between 330 and 580 °C to study the effect on product yields and oil composition. Apart from the physical−chemical analysis, a pyrolysis oil quality assessment has been performed by using two applications. The pyrolysis oils were tested in a laboratory scale atomizer and in a hydrodeoxygenation unit for upgrading/stabilizing of the pyrolysis oil. The pyrolysis oil yield increases from 330 to 450 °C, is nearly constant between 450 and 530 °C, and decreases again at a pyrolysis temperature of 580 °C. At temperatures of 360 and 580 °C, total pyrolysis oil yields of, respectively, 58 and 56 dry wt % can still be obtained. The produced amount of water is already significant at a reactor temperature of 360 °C and becomes constant at a temperature of 400 °C. At a temperature of 580 °C, the water production starts to decrease slightly. Initially the number average molecular weight of the pyrolysis oil increases at increasing temperatures, which is ascribed to the observed increase in concentration of water insoluble compound in the pyrolysis oil. At a temperature of 580 °C, the number average molecular weight, viscosity, and the amount of produced water insoluble compounds decreases. The oil obtained at a pyrolysis temperature of 360 °C produced less char, 2 versus 5 wt %, compared to the oil obtained at a pyrolysis temperature of 530 °C in our atomizer/gasifier. About 100% of the carbon goes to the gas phase compared to 84% for the oil obtained at a pyrolysis temperature of 530 °C. Therefore, the 360 °C oil has a better quality for this unit under the applied conditions (850 °C and droplet sizes of 50± μm) Testing the three pyrolysis oils (pyrolysis temperatures of 330, 530, and 580 °C) in the hydrodeoxygenation unit showed that pyrolysis oil with a lower viscosity resulted in deoxygenated oil of lower viscosity. The oxygen content of the three oils was almost the same, but the yield of the deoxygenated oils obtained at a pyrolysis temperature of 330 °C was significantly lower. Together with chemical and physical analyzes of the pyrolysis oils, feeding the pyrolysis oil into a test units relevant for applications, direct information on the effect of varied pyrolysis process parameters on the quality and applicability of the pyrolysis oil is obtained.

Fast pyrolysis kinetics of expanded polystyrene foam

AbstractFast pyrolysis of polymers, biomass and other substances is of great interest in various applications. For example, in the lost foam casting process, kinetic information about expandable polystyrene (EPS) decomposition under extremely high‐heating rate conditions is essential for further process development. A simple laboratory‐scale fast pyrolysis technique has been developed and demonstrated for elucidation of EPS decomposition kinetics. Pyrolysis experiments were performed at different reaction temperatures. The cumulative gaseous yields were determined using a flame ionization detector (FID) connected in series with the fast pyrolysis reactor. The governing equations for a semibatch reactor type were modified and applied to obtain kinetic parameters (activation energies and the pre‐exponential rate constants) for the EPS decomposition process. © 2009 American Institute of Chemical Engineers AIChE J, 2010

Use of lignin separated from bio-oil in oriented strand board binder phenol-formaldehyde resins

Bio-oil produced from fast pyrolysis of biomass has been investigated as a renewable fuel and as a source of industrial chemicals. The lignin fraction of bio-oil produced from wood in our fast pyrolysis reactor was separated by using only water and methanol with a 25% yield based on bio-oil weight. This separation procedure appears to be of lower cost than the reported extraction procedure using ethyl acetate as solvent. The isolated pyrolytic lignin was smoothly incorporated into phenol-formaldehyde resins at 30%, 40%, and 50% phenol replacement levels, and the resultant resins were evaluated as oriented strand board core-layer binders. The evaluation results indicated that the pyrolytic lignin is effective for up to about 40% replacement of phenol in synthesizing wood adhesive type PF resins.

Separation of bio-oil by molecular distillation

In this study, KDL5 molecular distillation apparatus manufactured by the UIC Corporation was adopted to separate bio-oil, which came from a bench-scale fluidized-bed fast pyrolysis reactor at a feeding rate of 1 kg/h. A maximum distillate yield of 85% was obtained without obvious coking or polymerization during the molecular distillation process. The effect of distillation temperature on physical and chemical characterization of each bio-oil fraction was investigated. Statistical calculations showed that molecular distillation was successful in the separation of bio-oil. A separation factor was proposed to reflect the ability of isolating the chemicals contained in the bio-oil using molecular distillation.

Fundamental Studies of NOx Emission Characteristics in Dimethyl Ether (DME)/Air Non-premixed Flames

The NOx emission characteristics of dimethyl ether (DME) in laminar co-axial jet and counterflow non-premixed flames were investigated using experimental and numerical approaches, respectively. The flame structure and NOx emissions of DME were compared to those of C2H6, which has equivalent methyl structures but lacks an oxygen atom. Experimental results showed that, in the co-axial jet case, the combustion of DME had the characteristics of a partial premixed flame. Additionally, it had a shorter flame and lower NOx emissions compared to the C2H6 flame. It is thus concluded that the major cause of low NOx emissions from DME co-axial jet flames may be the short flame length because of the lower stoichiometric air/fuel ratio. The activation of reburning NO chemistry because of the characteristics of the partially premixed flame may also play a role. The computational results of the DME counterflow non-premixed flame revealed that the EINO decreased by approximately 50% relative to that of the C2H6 flame. Although the overall NOx reaction path of the DME flame is similar to that of the C2H6 flame, it is concluded that the DME non-premixed flame has a distinct NO reduction mechanism. This is associated with reburning NO chemistry in the fuel-rich region because of fast pyrolysis and oxidation reactions in comparison to that of the C2H6 flame.

直パルス通電法を利用した新規な木質バイオマス急速熱分解装置の開発

木質バイオマスからバイオオイルと木質炭素化物の2つの生成物を効率よく変換するため，直パルス通電法を取り入れた新しい急速熱分解装置を開発した。本熱分解装置の新規性は，直流の大電流を発生する特別なインバーター電源をもつ直パルス通電法を装置の熱分解部に適用した点にある。この電源を用いることにより，従来型の熱分解炉では起り得ない，木質バイオマス原料の粒子の間で微小時間内に放電現象が発生することが期待できる。熱伝導が良くなるように微粉末化した125-250μmの粒度の木粉を原料に用い，50 g/hの搬送量で直パルス通電により加熱したチタン製パイプヒーターの中に連続供給して，400-550℃の反応温度で熱分解実験を行った。熱分解温度が450℃の時に，最大値40％の収率でバイオオイルが得られ，このオイルの高位発熱量は16 MJ/kgであった。また，熱分解温度500℃で加熱した際，プラス電極に付着した木質炭素化物にリング状のグラフェン層をもつポーラスナノカーボンの形成を確認した。

Hydrodynamics of a Novel Biomass Autothermal Fast Pyrolysis Reactor: Flow Pattern and Pressure Drop

AbstractA novel biomass, autothermal, fast pyrolysis reactor with a draft tube and an internal dipleg dividing the reactor into two interconnected beds is proposed. This internally interconnected fluidized beds (IIFB) reactor is designed to produce high‐quality bio‐oil using catalysts. Meanwhile, the pyrolysis by‐products, i.e., char, coke and non‐condensable gases, are expected to burn in the combustion bed to provide the heat for the pyrolysis. On the other hand, the catalysts can be regenerated simultaneously. In this study, experiments on the hydrodynamics of a cold model IIFB reactor are reported. Geldart group B and D sand particles were used as the bed materials. The effects of spouting and fluidizing gas velocities, particle size, static bed height and the total pressure loss coefficient of the pyrolysis bed exit, on the flow patterns and pressure drops of the two interconnected beds are studied. Six distinct flow patterns, i.e., fixed bed (F), periodic spouted/bubbling bed (PS/B), spouted bed with aeration (SA), spout‐fluidized bed (SF), spout‐fluidized bed with slugging (SFS) and spouted bed with backward jet (SBJ) are identified. The investigations on the pressure drops of the two beds show that both of them are seen to increase at first (mainly in the F flow pattern), then to decrease (mainly in the PS/B and SA flow patterns) and finally to increase again (mainly in the SA and SF flow patterns), with the increase of the spouting gas velocity. It is observed that a larger particle size and lower static bed height lead to lower pressure drops of the two beds.

State of art of biomass fast pyrolysis for bio-oil in China: a review

This paper presents a review of biomass fast pyrolysis for the production of bio-oil in Mainland China. The main contents are as follows. The feedstock for fast pyrolysis and main pyrolysis reactor developed in Mainland China are introduced. The process of fast pyrolysis for each pyrolysis reactor mentioned in this paper is described. The effects of key parameters of fast pyrolysis on fluidised bed reactor are illustrated. Finally, the properties, upgrading and application of bio-oil are discussed.

Experimental study of pyrolysis for potential energy, hydrogen and carbon material production from lignocellulosic biomass

Experimental results of slow, fast and catalytic pyrolysis of five lignocellulosic residues (corncobs and corn stalks, sunflower residues, olive kernels and olive tree prunings) are reported in this paper. Pyrolysis took place in two different reactor configurations: a captive sample wire mesh reactor for fast pyrolysis and a fixed bed reactor for non-catalytic and catalytic pyrolysis. Comparison of the experimental results showed that pyrolysis in the captive sample reactor produced more H 2-rich gas than in the fixed bed reactor, while the fixed bed reactor configuration seemed to favor the production of liquid products. Analysis of gaseous, liquid and solid products was performed by GC and GC/MS. Pyrolysis results were assessed, and recommendations for the further use of their products were made.

Simulating the behavior of a wire mesh reactor for olive kernel fast pyrolysis

Abstract The simulation of the behavior of a wire mesh reactor is presented in the following study making use of models extracted from the literature. Two different kinetic models are used, coupled with heat transfer model, mass conservation equations, continuity equations and momentum equations. The numerical method applied is finite difference for the momentum, mass conservation, heat transfer and continuity equations and Runge–Kutta fourth order for the chemical kinetic model equations. Simulations are carried out for spherical olive kernel particles with radius of 175 μm, reactor temperature 873 K and heating rates of 200 K/s. The simulation works satisfyingly under the hypothesis of ablative behavior and the results are in very good agreement with the experimental data regarding temperature, conversion histories and product distribution of olive kernel fast pyrolysis.

CFB air-blown flash pyrolysis. Part I: Engineering design and cold model performance

Abstract The objective of this work was to design, construct and test a novel circulating fluid bed fast pyrolysis reactor system for production of liquids from biomass. The novelty lies in incorporating an integral char combustor to provide autothermal operation of the reactor. A reactor design methodology was devised which correlated input parameters to process variables, namely temperature, heat transfer and gas/vapor residence time, for both the char combustor and biomass pyrolyser. From this methodology, a CFB reactor was designed with integral char combustion for 10 kg/h biomass throughput. A full-scale cold model of the CFB unit was developed and tested to derive suitable hydrodynamic relationships and performance constraints. The hot CFB reactor was constructed, its operability was tested and appropriate modifications were accomplished prior to the commissioning. A major requirement for the desired dual-mode operation of the reactor system conceived was the close coupling of the two reactor subsystems, namely the pyrolysis riser (medium temperature) and char combustor (high temperature). The basic CFB reactor design was proven effective in providing the high heat transfer rates – expressed as low voidage values in the riser and high solid circulation rates – to biomass particles in the very short vapor residence times (VRTs) required. The understanding of the complicated aspects related to two-phase gas–solids flow in the standpipe resulted in a smooth, stable transfer of solids over a wide range of operating parameters during cold CFB reactor operation. In the hot CFB unit testing, the use of two and three cyclones in series was proved insufficient to capture char and unconverted wood particles, especially during the reactor start-up phase. These problems were partially faced by adopting a configuration of a primary cyclone and inertia impinger in series, but further development is still required. A variety of configurations for the product collection system were built and tested, the most efficient being a combination of a shell-and-tube heat exchanger (condenser) and a cotton wool filter. However, the liquid recovery configuration gave rise to a number of problems, the most important being gradual plugging of the heat exchanger due to the formation of sticky solid–liquid agglomerates.

Enthalpy for Pyrolysis for Several Types of Biomass

This study utilizes a pilot-scale pyrolysis system to determine the enthalpy for pyrolysis for Northern Red Oak (Quercus rubra), Western White Pine (Pinus monticola), corn stover, and oat hulls. The analytical method uses an energy balance on a pyrolytic reactor. The energy required is measured at a fast pyrolysis reactor temperature near 500 °C using nitrogen as an inert fluidizing agent in a fluidized bed reactor. On a dry basis, the energy necessary to pyrolyze these fuels varies between 0.8 ± 0.2 MJ/kg for oat hulls and 1.6 ± 0.3 MJ/kg for pine.

99/01071 Catalytic fast pyrolysis of biomass : Salter, E. H. et al. IChemE Res. Event, Two-Day Symp., 1998, 89–96

99/01071 Catalytic fast pyrolysis of biomass : Salter, E. H. et al. IChemE Res. Event, Two-Day Symp., 1998, 89–96

99/01337 Design aspects of fast pyrolysis reaction systems for liquids from biomass : Peacocke, G. V. C. et al. IChemE Res. Event, Two-Day Symp., 1998, 105–113

99/01337 Design aspects of fast pyrolysis reaction systems for liquids from biomass : Peacocke, G. V. C. et al. IChemE Res. Event, Two-Day Symp., 1998, 105–113