Biomass Particle Size Research Articles

A comparative study on valuable products: bio-oil, biochar, non-condensable gases from pyrolysis of agricultural residues

In this study, pyrolysis of agricultural residues, such as rice straw (RS), wheat straw (WS), and sugarcane bagasse (SB), was performed in a fixed-bed reactor. The experiments were carried out at varying operating conditions, such as temperature, heating rate, biomass particle size and sweeping gas flow rate, such that the bio-oil yield could be maximized. Small particle size and high heating rate contributed to more bio-oil yield as compared to large particle size and low heating rate. Physicochemical properties of bio-oil samples, evaluated in a comparative manner with maximum focus devoted on analyzing the chemical constituents through GC–MS and FTIR analysis. Biochar was also examined through different physicochemical techniques (e.g., HHV, pH, SEM–EDX, FTIR, CHNS, ICP-AES) for understanding pyrolysis mechanism and its practical usability. Analysis of non-condensable gas through GC-TCD, revealed co-existence of H2, CO, CO2 and CH4 molecules, with greater percentage of H2 and CH4 at high temperature resulted enhancement in calorific value.

Experimental study on specific grinding energy and particle size distribution of maize grain, stover and cob

Reducing the particle size of biomass is of great significance for rational and efficient utilization of biomass. In this study, maize grain, stover, and cob were comminuted at different speeds (2000-2800 r/min) by hammer mill with a mesh size of 2.8 mm. The mechanical energy for smashing three selected samples was obtained directly through the sensor and data testing system. Experimental results demonstrated that the maize cob had the highest total specific energy while the maize grain had the lowest (135.83-181.10 kW·h/t and 27.08-36.23 kW·h/t, respectively). In addition, for the same material, higher hammer mill speed generated more specific energy consumption. And the effective specific energy of maize stover had a similar trend to the total specific one. However, the effective specific grinding energy of maize cob and grain increased initially and then decreased with the increase of rotating speed. The fitting curves of the specific energy to mill speeds were determined, and the range of determination coefficients of the regression equation was 0.933-0.996. Particle size distribution curves were drawn by sieving the pulverized particles of the three samples based on a series of standard sieves. Fourteen relevant parameters characterizing the particle size distribution were calculated according to the screening data. Calculation results demonstrated that larger rotational speed leads to smaller particle sizes. Combining the size parameters, distribution parameters, and shape parameters, it was found that the distributions of the three samples all exhibit a distribution of “well-graded fine-skewed mesokurtic”. The Rosin-Rammler function was considered to be suitable for characterizing the particle size distribution of maize grain, stover, and cob particles with a coefficient of determination between 0.930 and 0.992. Keywords: maize grain, maize stover, maize cob, specific energy, particle size distribution, comminution DOI: 10.25165/j.ijabe.20201304.5327 Citation: Xue Z, Fu J, Chen Z, Ren L Q. Experimental study on specific grinding energy and particle size distribution of maize grain, stover and cob. Int J Agric & Biol Eng, 2020; 13(4): 135–142.

The Impact of Fractional Composition on the Mechanical Properties of Agglomerated Logging Residues

Fractional composition, as well as the temperature of the agglomeration process, affect the quality and mechanical properties of briquettes. In this research, shredded forest logging residues were investigated. Compaction tests were carried out for several specially prepared mixtures made of shares of fractions with different particle sizes. The moisture content, density of briquettes, specific work of compaction, mechanical durability, and biomass susceptibility to compaction were analyzed. Studies have confirmed the significant impact of the fractional composition of compacted biomass on its susceptibility to process parameters and the quality of the final product. Statistical analysis confirmed that the density of the briquette, its durability, the specific work of compaction, and the susceptibility of the tested biomass to compaction strongly depend on the particle size of the compacted biomass. An increase in temperature to 73 °C increased specific work by 40% and contributed to the high quality of briquettes in the range from 0.768 to 1.14 g·cm−3.

Nickel adsorption from aqueous solution using lemon peel biomass chemically modified with TiO2 nanoparticles

Adsorption technique has attracted considerable attention as a promising alternative for reducing heavy metal ions in water sources. This work is focused on the adsorption of nickel ions using lemon peel biomass chemically modified with titanium dioxide (TiO2) nanoparticles through siloxane bonds. The biomass was characterized by FT-IR and compositional analyses to identify functional groups and elemental composition. From these measurements, it was observed peaks at 1741, 1328, and 1229 cm−1, characteristics of CO, C–O, and C–H stretching bands, respectively. These organic bonds can be related to the existence of cellulose, lignin, and pectin biopolymers, which are present in the lemon peel biomass, as observed from the compositional analyses. After grafting TiO2 nanoparticles onto lemon peel biomass surface, it was observed from FTIR the presence of vibrational bands at 1524, 1054, and 943 cm−1, characteristics of –Ti-O-C, –Si-O-Si, and –Ti-O-Si functional groups. Additionally, the morphology and elemental composition of the lemon peel biomass modified with the titanium dioxide (TiO2) nanoparticles were determined by SEM microscope, observing the presence of C, O, Ti, and Si atoms from the EDS mapping. Batch adsorption experiments were carried out to determine the effect of pH and biomass particle size on adsorption of Ni (II) ions from aqueous solution. From these experiments, maximum adsorption of Ni (II) ions of 78 ± 0.2% was obtained at pH 6.0, while no significant effects were observed for biomass particle size. Furthermore, the modification of biomass with TiO2 nanoparticles increased up to 90 ± 0.1% the Ni (II) ions adsorption, suggesting the potential of the biomass modified with metal oxide nanoparticles for removal of heavy metal ions.

On the characteristic heating and pyrolysis time of thermally small biomass particles in a bubbling fluidized bed reactor

Abstract Pyrolysis of crushed olive stone particles in a lab scale Bubbling Fluidized Bed (BFB) reactor was investigated. The time evolution of the pyrolysis conversion degree of the olive stone particles, while moving freely in the BFB, was determined from the evolution of the mass of olive stones remaining in the bed, measured by a precision scale holding the whole reactor installation. The experimental measurements of the pyrolysis conversion degree were employed to validate a simple model combining heat transfer and chemical kinetics, which is valid for thermally small particles. The model combines the Lumped Capacitance Method (LCM) and the simplified Distributed Activation Energy Model (DAEM) to account for heat transfer and pyrolysis chemical kinetics, respectively. The estimations of the combined LCM-DAEM model for the pyrolysis conversion degree were found to be in good agreement with the experimental measurements for the pyrolysis of olive kernels in a BFB operated at various bed temperatures, fluidizing gas velocities, and biomass particle size ranges. From the combined LCM-DAEM model, the characteristic heating time and the pyrolysis time of the olive stone particles were derived, obtaining a direct relation between these two parameters for constant values of the bed temperature.

Minor Biomass Particle Size for an Efficient Cellulose Accessibility and Enzymatic Hydrolysis

AbstractSugarcane bagasse is a recalcitrance lignocellulosic material with difficult to structure disorganize and it has low cellulose accessibility, negatively influencing the enzymatic saccharification. This study identified the minor particle size that resulted in the efficient diluted acid pretreatment (10 % m/m, 121 °C/30 min) of sugarcane bagasse and a more recalcitrant material, that is external fraction (2 to 3 mm from the extremity, containing epidermis). Particle sizes were obtained by sieving sugarcane bagasse at 16 (1 mm), 24 (0.710 mm), 35 (0.425 mm), 60 (0.250 mm) and <60 mesh (<0.250 mm) on a sieve agitator. The decrease of the particle sizes led to an increase of cellulose accessibility. Both of the samples showed high accessibility after the pretreatment due to the particle size decrease. Accordingly, there was a better enzyme action, what increased the glucose yield with samples lower than 0.425 mm (35 mesh).

A Parametric Study of an Experimental Gasifier by Taguchi Methods

Parametric studies performed using Taguchi methods in order to optimize an experimental process and the results of the development of a laboratory vertical fixed-bed gasifier are reported. It was demonstrated that gasification is a reliable process on a laboratory scale and its results can be used at pilot plants. It was found that the frequency of sample injection at constant weight, the particle size of biomass, and the amount of secondary air have a greater effect on the formation of CO and H2 than that of the moisture content of the biomass and the process temperature.

Experimental investigation on the production of bio-oil from wheat straw

ABSTRACT The utilization of waste biomass such as crop residues in the production of biofuel is gaining attention from all around the world. The wheat is one of the most grown crops in the world and its main by-product straw produced 529 million tons per annum. The present study aims to investigate the feasibility of wheat straw as biomass material to produce bio-oil in a fluidized bed fast reactor. The developed system has a throughput capacity of 5 kg/h and the effect of varying temperature, biomass particle size, and sweep gas flow rate on the yield of pyrolysis products mainly on bio-oil is also studied. The result showed that the highest bio-oil yield 42 wt% was obtained at a temperature of 500°C, the feed particle size of 1 mm, and the gas flow rate of 4 m3/h. The properties of produced bio-oil were determined such as heating value, viscosity, and pH of 19.59 MJ/kg, 18.01 cP, and 3.1, respectively. The GCMS and FTIR analysis were used to identify the chemical compounds available on bio-oil and the phenol, alcohols, alkanes, alkenes, esters, furnol, hydrocarbon, and aromatic compounds were reported in the bio-oil. The economic assessment showed that the production cost of bio-oil was 0.50 US$/liter and the calculated payback period of the system was 1.57 years.

Kinetics and equilibrium studies on biosorption of hexavalent chromium from leather tanning wastewater by Sargassum tenerrimum from Chabahar-Bay Iran

The traditional leather tanning is one of the oldest technologies which produces effluents containing different pollutants, including Cr(VI) oxyanions. In this lab-scale study, batch experiments were conducted to measure Cr(VI) removal capacity of Sargassum tenerrimum. The efficacy of biosorption was optimized considering variables including pH, temperature, initial chromium concentration, as well as biomass particle size and dosage. Surface characteristics of S. tenerrimum and its changes after Cr(VI) adsorption were investigated by BET/BJH, SEM-EDX and FT-IR techniques. Desorption studies were carried out to investigate the capability of multiple uses of the algal biomass, with the results showing a high performance of five successive sorption/desorption cycles. The maximum biosorption was obtained with the biomass particle size of 0.6 mm at 25 °C at pH 2. The Langmuir isotherm model was recognized as the most correlated model of biosorption where the maximum biosorption capacity (qmax) was obtained to be 37.7 mg/g dry biomass. The batch experiments were repeated using real tannery wastewater under the optimized conditions and the biosorbent could remove about 88% of Cr(VI) from the real wastewater.

Mesoscale Reaction-Diffusion Phenomena Governing Lignin-First Biomass Fractionation.

Lignin solvolysis from the plant cell wall is the critical first step in lignin depolymerization processes involving whole biomass feedstocks. However, little is known about the coupled reaction kinetics and transport phenomena that govern the effective rates of lignin extraction. Here, we report a validated simulation framework that determines intrinsic, transport-independent kinetic parameters for the solvolysis of lignin, hemicellulose, and cellulose upon incorporation of feedstock characteristics for the methanol-based extraction of poplar as an example fractionation process. Lignin fragment diffusion is predicted to compete on the same time and length scales as reactions of lignin within cell walls and longitudinal pores of typical milled particle sizes, and mass transfer resistances are predicted to dominate the solvolysis of poplar particles that exceed approximately 2 mm in length. Beyond the approximately 2 mm threshold, effectiveness factors are predicted to be below 0.25, which implies that pore diffusion resistances may attenuate observable kinetic rate measurements by at least 75 % in such cases. Thus, researchers are recommended to conduct kinetic evaluations of lignin-first catalysts using biomass particles smaller than approximately 0.2 mm in length to avoid feedstock-specific mass transfer limitations in lignin conversion studies. Overall, this work highlights opportunities to improve lignin solvolysis by genetic engineering and provides actionable kinetic information to guide the design and scale-up of emerging biorefinery strategies.

Influence of Raw Material Properties on Parameters of Injection Press during the Injection of Composites Based Biomass and Plastic Waste

The main aim of this paper is to present the research findings which come out from the experimental determination of the influence of input raw material properties and composition on the operating parameters of an injection press during the injection of biomass-plastic composites (BPC). During the injection process, important operating parameters such as injection speed, injection pressure and the temperature profile along the chamber can be recognized. In this research study, the aim was to produce BPCs of an acceptable and competitive level of quality which is determined from the final mechanical properties of BPCs. Using a variety combination of influencing variables the final quality of composites and also the operating parameters of the injection moulding press can be improved. Raw waste material variables influence, especially (a type of plastic matrix, type of biomass, particle size, moisture content) and biomass/plastic concentration ratio can be recognized during the production of composites. Their effect can be seen from the quality indicators and from the operating parameters of the injection press which has a direct impact on the production costs. The paper deals with the determination of the impact and the relationship between the input raw material variables and the operating parameters of the injection process (pressure, speed, and temperature profile). The experimental research findings were obtained using a semi-operational injection moulding press where the injection is provided by a working screw. As the input raw material, wheat straw and spruce sawdust, HDPE plastic matrix and recycled HDPE, represented by lids from PET bottles, was used. The effect of the input raw material composition was determined according to a combination and default levels of biomass/HDPE concentration ratio, using recycled HDPE instead of virgin HDPE and particle size of biomass.

Biochar production from palm oil mill residues and application of the biochar to adsorb carbon dioxide

The amount of palm oil mill residues increases rapidly and will become a severe problem in the future. One potential technique for alleviating this concerning environmental problem is to convert these residues into biochar by the pyrolysis process. Pyrolysis of three types of palm oil mill residues (namely, palm kernel shells, empty palm fruit bunches, and oil palm fibers) was conducted in a fixed bed reactor at 500 °C and 2 L/min of nitrogen flow rate for 60 min. The optimization of biochar production was performed using the Box-Behnken design and analyzed using response surface methodology. The effects of three potential factors, including pyrolysis temperatures, nitrogen flow rates, and biomass particle sizes, were studied. The results showed that the highest biochar yield (44.91 wt%) was obtained from pyrolysis of palm kernel shells at 525 °C with a nitrogen flow rate of 2 L/min and a particle size of 750 μm. Application of biochar produced from palm kernel shells for carbon dioxide capture was tested in a packed bed adsorber of 3.0 g of biochar sample by flowing 1,400 ppm of carbon dioxide in the gas feed mixture at 2.5 L/min. The capacity of the biochar sample for CO2 adsorption was 0.46 mmol/g.

EXTRACTION AND EVALUATION OF OIL FROM GREEN ALGAE CLADOPHORA GLOMERATA BY HEXANE/ETHER MIXTURE

The overall aim of this study was to grow green algae <em>Cladophora glomerata</em>, extract oil from it, and characterize the extracted oil to gain insight into its physicochemical properties. The effects of parameters affecting the solvent extraction process, temperature, time and biomass particle size were investigated at a fixed solvent ratio of 4:1 hexane to ether. An optimization of oil separation from algae biomass via the solvent extraction method was studied. The obtained results showed that at the extraction temperature of 60 oC, extraction time of 2.5 h, and the particle size of ≤0.6 mm, the maximum oil yield was 18.3% from the process. The functional group analysis revealed the presence of alkane, esters, carboxylic acid, and unsaturated groups on the extracted oil, while the result from the fatty acid profile analysis confirmed the dominance of oleic acid. The physicochemical properties of the extracted algal oil conformed to the ASTM standard.

One-Pot Deconstruction and Conversion of Lignocellulose Into Reducing Sugars by Pyridinium-Based Ionic Liquid-Metal Salt System.

Constantly decreasing fossil resources and exceeding energy demands are the most alarming concerns nowadays. The only way out is to develop efficient, safe, and economical biomass processing protocols that can lead toward biofuels and fine chemicals. This research is one of such consequences involving the deconstruction and conversion of wheat straw carbohydrate constituents into reducing sugars via one-pot reaction promoted by Lewis acidic pyridinium-based ionic liquids (PyILs) mixed with different metal salts (MCl). Various parameters such as the type of metal salt, loading amount of metal salt, time, temperature, particle size of biomass, and water content which affect the deconstruction of wheat straw have been evaluated and optimized. Among the studied ionic liquid (IL) and metal salt systems, the best results were obtained with [BMPy]+. The dinitrosalicylic acid (DNS) assay was used to determine the percentage of total reducing sugars (TRS) generated during treatment of wheat straw. The deconstructed wheat straw was characterized with various analytical tools, that is, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) analyses. The IL–metal salt system was recycled for subsequent treatment of wheat straw. Statistical parameters were calculated from analysis of variance (ANOVA) at the 0.05 level of confidence.

Thermogravimetric analysis and reaction kinetics of lignocellulosic biomass pyrolysis

The elucidation of the biomass pyrolysis characteristics will provide valuable guidance for the design of pyrolysis devices. The pyrolysis kinetics characteristics of lignocellulosic biomass were studied by thermogravimetric analysis, and the main influencing factors, including biomass particle size, heating rate, and metal ion, were investigated. With a decrease in the particle size of rice straw and pine sawdust, the initial and final pyrolysis temperatures and the temperature of the maximum weight loss ratio decreased. Opposite results were obtained for Phoenix tree leaves. Furthermore, the initial release temperature of volatile matter and the temperature corresponding to the peak of the derivative thermogravimetric curves increased with an increase in heating rate. Moreover, the pyrolysis activity of rice straw decreased significantly after deashing but increased with the addition of potassium. The pyrolysis kinetics parameters were calculated by the Coats–Redfern, Doyle, and the distributed activation energy model (DAEM) methods. The apparent activation energy of pyrolysis was the lowest, varying between 30 and 70 kJ/mol, according to the fitting results of the Coats–Redfern method. The apparent activation energies calculated by the DAEM and Doyle methods are similar, and are 67.6, 245.8, and 271.8 kJ/mol for rice straw, pine sawdust and Phoenix tree leaves, respectively.

Extraction of High-Purity Lignins via Catalyst-free Organosolv Pulping from Low-Input Crops.

A catalyst-free organosolv pulping process was applied to cup plant (Silphium perfoliatum, S), Miscanthus grass (Miscanthus x giganteus, M), and the Paulownia tree (Paulownia tomentosa, P), resulting in high-purity lignins with no signals for cellulose, hemicellulose, or other impurities in two-dimensional heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectra. Different biomass particle sizes used for the organosolv pulping (1.6-2.0 mm (1); 0.5-1.0 mm (2); <0.25 mm (3)) influenced the molecular weight and chemical structure of the isolated lignins. Principal component analysis (PCA) of 1H NMR data revealed a high intergroup variance of Miscanthus and Paulownia lignins, separating the small particle fraction from the larger ones. Furthermore, monolignol ratios identified via HSQC NMR differ significantly: Miscanthus lignins were composed of all three monolignols (guaiacyl (G), p-hydroxyphenyl (H), syringyl (S)), while for Paulownia and Silphium lignins only G and S units were observed (except for P3).

Hydrothermal gasification of soybean straw and flax straw for hydrogen-rich syngas production: Experimental and thermodynamic modeling

Biofuels produced from lignocellulosic feedstocks are gaining popularity because of the elevating energy demand, increasing greenhouse gas emissions, escalating fuel prices and dwindling fossil fuel resources. Therefore, it has become important to seek alternative energy resources from renewable waste biomass. In this study, agricultural crop residues such as soybean straw and flax straw were gasified in subcritical water (300 °C) and supercritical water (400 and 500 °C) for H2 production. To maximize the non-catalytic process, the impacts of temperature (300–500 °C), biomass-to-water ratio, BTW (1:5 and 1:10), biomass particle size (0.13 mm and 0.8 mm) and residence time (30–60 min) on H2 production were studied at a pressure range of 22–25 MPa. Maximum H2 yield and total gas yields of 6.62 mmol/g and 14.91 mmol/g, respectively were obtained from soybean straw at the highest temperature (500 °C), lower feed concentration (1:10 BTW), smaller particle size biomass (0.13 mm) and longer residence time (45 min). To evaluate the drift in the experimental H2 yield from the theoretical values, thermodynamic modeling using Gibbs free minimization method was performed. The experimental results showed slight deviations from the thermodynamic models due to the temperature gradient and absence of agitation in the tubular batch reactor. However, the KOH catalyst was found to elevate the H2, CO2 and CH4 yields for soybean straw and flax straw. The findings suggest that supercritical water gasification could be an efficient green technology for H2 production from waste biomass.

Optimal particle size for fermentable sugar production from Miscanthus sacchariflorus var. No. 1 (Goedae-Uksae 1) considering energy consumption for comminution

In this study, energy consumption for two stages of comminution of M. sacchariflorus and fermentable sugar production by hydrothermal pretreatment and enzymatic hydrolysis are investigated. Biomass comminution is carried out in two stages, which are chopping (18, 40, 80, and 160 mm length) and grinding using three screen sizes (3, 5, and 7 mm). In the chopping process, the highest total specific net energy efficiency is 17.35 kJ/kg when the biomass is chopped to 18 mm length. In the grinding process with chopped biomass, the total specific net energy efficiency ranges from 18.49 to 38.38 kJ/kg. In summary, the highest total specific net energy efficiency during the two stages of comminution is 44.58 kJ/kg when the biomass is chopped to 80 mm length and is sequentially ground to pass a screen size of 3 mm. The total fermentable sugar production ranges from 64.76 to 76.27 g/L, which is obtained from hydrolysate and enzymatic hydrolysis, depending on the biomass particle size. The highest fermentable sugar production is 76.27 g/L when hydrothermal pretreatment and enzymatic hydrolysis is performed with the ground biomass (chopping to 18 mm and sequentially ground to pass 3 mm screen). Considering the total fermentable sugar production and the total specific net energy efficiency, 18 mm length and less than 7-mm screen size is considered suitable for the chopping and the grinding, respectively, for the comminution of M. sacchariflorus.

Development in biomass preparation for suspension firing towards higher biomass shares and better boiler performance and fuel rangeability

Suspension-firing enjoys the great popularity in biomass-fired heat and power generation. Since it has the strictest requirement on fuel quality and particle size, cares must be taken in biomass handling. This paper reviews, combined with concrete cases, the development in biomass preparation methods for suspension-firing: the processes and their impacts on critical issues in biomass suspension-firing. The first-generation preparation method, based on raw biomass, was successfully used for biomass suspension co-firing at low shares and nowadays is mainly used for other combustion technologies, due to the large particles it produces. The second-generation method, based on biopellets, is commonly used in existing suspension-firing plants. It can reduce biomass particle size to 85% < 1 mm (maximum 3 mm), ensuring good ignition and particle burnout. 100% biomass suspension-firing is mainly for high-quality biomass and often uses additives to mitigate corrosion. To improve fuel rangeability, the third-generation method will be prevailing. It includes extra thermal pre-treatment for increasing the energy density and grindability of the feedstock. Suspension-firing trials of torrefied biopellets are performed at several power plants. It is too costly in the present energy market and can be promoted by a future regulatory condition change in favor of alternative solid fuel sources.

Effects of chemical composition, mild alkaline pretreatment and particle size on mechanical, thermal, and structural properties of binderless lignocellulosic biopolymers prepared by hot-pressing raw microfibrillated Phoenix dactylifera and Cocos nucifera fibers and leaves

We developed value-added, high-strength lignocellulosic biopolymers by exploiting high-lignin biomass waste of palms. Lignocellulosic biopolymers were prepared by hot-pressing microfibrillated raw and alkaline pre-treated date and coconut fibers and leaves powders consisting of (≤53–≤106 μm) particles in the range 140–180 °C. The obtained biopolymers were subjected to three-point bending strength, water resistance, structural morphology (SEM), thermal stability (TGA/DTG), spectroscopy (FTIR), and crystallinity (XRD) analyses. Findings showed that raw fiber-based and alkaline-pretreated biopolymers exhibited bending strength, water resistance, and thermal stability (~200 °C) superior to those of leaf-based biopolymers. Furthermore, lignocellulosic biopolymers prepared from smaller particles showed enhanced bending and thermal properties, compared to those prepared from large particles. By mechanical and thermal properties, the optimum results were observed for biopolymers pre-treated with 1 wt% NaOH, except for coconut leaf-based biopolymers. Results were correlated to chemical composition and particle size of milled lignocellulosic biomass, allowing for efficient lignin condensation.