Physical Properties Of Pellets Research Articles

A way towards zero-waste campaign and sustainability in sugar industries; filter cake valorisation as energy pellets

A by-product known as filter cake has been a major problem for sugar industries. Despite its use as fertiliser, millions of tonnes of filter cake have been discarded as waste. Thus, the concept of wastevalorisation is highly essential to the production of useful energy. Filter cake consists of fine particulates with a high moisture content; consequently, crushing is not necessary for pelletisation. A preliminary investigation has demonstrated the tremendous potential of filter cake pellets with a higher heating value of 8–12 MJ/kg, depending on their moisture content. However, pelletisation must be properly optimised. In the present study, the initial moisture contents of filter cake werevaried between 10, 20, and 30%. The physical properties of pellets with these initial moisture levels were then determined and compared with EN 14961-1. Moreover, the relationship between particle and bulkdensities was determined and utilised for optimisation. The results indicated that an initial moisture content between 10 and 20% was suitable for pelletisation, with excellent conformance to the EN 14961-1 standard. The diameter, length, bulk density, particle density, fines, and durability values were 5.90–5.98 mm, 28.11–29.18 mm, 832.6–852.6 kg/m3,1517.3–1626.1 kg/m3, 0.22–0.30%, and 97.8–98.1%, respectively. In addition, a prototype system demonstrated the feasibility of the concept of waste valorisation for a zero-waste campaign. Furthermore, economic analysis indicated that if 2.04 million tonnes per year of filter cake pellets were utilised as fuels in steam power plants, they could generate 2.63x109 kWh of electricity per year, resulting in approximately 318 million US dollars.

Optimization of Process Parameters for Pellet Production from Corn Stalk Rinds Using Box–Behnken Design

In the current study, corn stalk rinds were used as feedstock for the production of solid-fuel pellets. In an effort to comprehensively analyze the effects of different operational parameters on the physical properties of pellets, response surface methodology (RSM) was employed in conjunction with a Box–Behnken experimental design (BBD). By assessing multiple variables simultaneously and examining their interactions, BBD facilitates the development of a reliable response model that can predict how changes in independent variables will impact response variables. The recorded responses included relaxed density, mechanical durability, and compressive strength. Based on the results, greater R2 values of 0.9467, 0.8669, and 0.9196, could be, respectively, attained for the quadratic regression models. The analysis of variance revealed that all independent variables had significant effects on the responses. The optimal processing condition for the pellets was established by determining the ideal combination of operational parameters. The process entailed the choice of a particle dimension measuring 0.5 mm, a moisture level of 11.35%, the application of heat at 125.7 °C on the die, and the utilization of a molding pressure of 154.2 MPa. Based on these factors, the predicted response values were determined to be 1639.61 kg/m3 for relaxed density, 97.95% for mechanical durability, and 10.18 MPa for compressive strength. The values obtained experimentally under the optimized conditions were similar to the predicted values with a desirability value of 1.00.

Comparison of the physical properties of cotton and sesame stalk pellets produced at different moisture contents and combustion of the finest pellets

ABSTRACT In this study, cotton and sesame stalks that are grown regionally and burned in coarse form as a source of heat energy form in the current application are used as pellet raw materials. Although these residues are used as biomass raw materials in different forms, there is limited information about their use as pellets. In order to compare the production efficiency and physical properties of the pellets obtained, production capacity, specific energy consumption, bulk density, particle density, durability, compression resistance, specific compression resistance, and tensile strength tests have been applied. In the moisture content ranges pellet durability, bulk density, particle density and tensile strength were achieved as 89–98%, 430–695 kg/m3, 921–1367 kg/m3, 2.83–7.28 Mpa for cotton stalk pellets, and 93–97%, 510–660 kg/m3, 4.26–5.85 Mpa for sesame stalk pellets, respectively. 20% pelletizing moisture for both stalks increased pellet production capacity, reduced energy consumption, but affected negatively their physical structures. It was concluded that the ideal pelleting moisture values for cotton stalks and sesame stalks were 10% and 15%, respectively. During combustion experiments, O2, CO2, CO, and NOx emissions, flue gas temperature, and combustion efficiency were observed. According to the results of combustion experiments, CO and NOx emissions were found to be 1646 ppm and 50 ppm for cotton stalks, 2862 ppm and 134 ppm for sesame stalks, respectively. High O2 emission values (18–19%) were observed for both pellets.

Physical Characteristic of Biomass Pellet from Cacao Pod Husk and Banana Pod Husk

Biomass is a suitable material to be developed as an alternative energy source to substitute fossil fuels. Waste of Cacao and banana processing (peel) are potentially forming into biomass pellets because they have high calorific value. Increasing the caloric value of biomass fuel can be done through the densification process to produce biomass pellets. This study aims to find the best-mixed formula and particle size (mesh), thus calculate the physical properties of the best biomass pellets. The quality of biomass pellets is determined by the physical properties of the pellets. Processing of biomass pellets is by drying cocoa skin and banana peel, grind with a hammer mill, and sieved with a size of 20, 40, and 60 mesh. Materials are mixed with composition of cacao pod husk and banana pod husk are 80% : 20%, 70% : 30%, 60% : 40%. Biomass is pressed using a hydraulic press with a diameter of 1 cm, and a height of 1 cm then dried to reduce the moisture content. The result shows the best formula of biomass pellets occurs in a combination of 80% cacao pod husk and 20% banana pod husk with 60 mesh. This biomass pellet has physical characteristics for calorific value of 4049,815 cal/g, a volatile matter value of 78,92%, moisture content of 5.17%, ash content of 9,8%, and density of 5,214 gr/cm3. Banana pod husk with high levels of lignin can be used as an adhesive, it binding cacao pod husk particles properly and increase density and calorific value.

Relationship between Raw Material Composition and Pellets Physical Properties

The mutual interaction between pellets quality, which is represented by the pellets physical properties, and the input composition of raw material is very interesting and complicated itself. Therefore, the main aim of this research paper is to determine the relationship between the raw material composition, which influences the pellets quality and the pellets quality indicators - physical properties of pellets. During the biomass densification, also the raw material properties significantly influence the final solid biofuels quality. Therefore the raw material composition represented by different mixtures from spruce sawdust, wheat straw and spruce bark, in various ratios (90/10, 80/20, 50/50, 80/10/10 and 50/30/20) and in various raw material composition (sawdust/straw, straw/bark, straw/sawdust/bark) were investigated. During this research study in total 14 different material composition was used. Effect of mentioned raw material mixtures on pellets bulk density, mechanical durability, abrasion, particle density and hardness were determined. Research findings presented in this paper are based on a realized experimental research that was done on Faculty of Mechanical Engineering STU in Bratislava. This experimental research was a logical result of and based on authors practical experience and wide theoretical analyses of selected variables influence. Described experimental research was realized by real pelleting machine that is a part of semi-production pelleting plant on Faculty of Mechanical Engineering STU in Bratislava. The experimental findings presented here are showing the importance of mentioned variables and parameters during the pelletizing process.

Thermo-physical characterization of torrefied fuel pellet from co-pelletization of canola hulls and meal

Agricultural processing residues, as renewable sources of energy, can be converted to value-added products such as fuel pellets with the wide applications in the production of heat and power. In this research, densification/torrefaction of canola meal and canola hull was investigated. A bench-scale extruder was used for densification of canola hull and canola meal. Then, to increase the hydrophobicity and heating value of pellets, they were torrefied. For pelletization of canola meal, an increase in canola meal to water mass ratio resulted in an increase in the mechanical strength of pellets. Canola meal was also used to facilitate pelletization of canola hull. Co-pelletization of canola hull with canola meal was successful for canola hull mass percentage up to 60 wt% in the feedstock. In general, torrefied pellets showed lower moisture adsorption (up to 59%), higher carbon content (in the range of 21–25%), lower oxygen content (35–46%), and higher heating value (up to 22%) compared with their respective precursors. To study the effects of operating conditions and additives, different characterization techniques were used to evaluate the thermal, chemical, mechanical, and physical properties of pellets. Synchrotron-based computed tomography showed that after torrefaction, porosity increased by 10% for pellets from canola meal and increased by 22–30% for pellets prepared by co-pelletization. Addition of alkali lignin to canola meal precursor helped to increase the mechanical strength of torrefied pellet produced from canola meal. The use of binders such as alkali lignin and crude glycerol had no effect on the relaxed density of torrefied pellets and resulted in higher moisture adsorption.

ASSESSMENT OF THE PRODUCTION VARIABLES ON THE PELLETIZATION PROPERTIES OF MICROCRYSTALLINE CELLULOSE II (MCCII)

Objective: To study microcrystalline cellulose II (MCCII) as new pelletization aid using the extrusion/spheronization technology.Methods: The effect of the spheronization rate and spheronization time was assessed by a response surface design. The shape descriptors and physical properties of pellets were taken as response variables. Approximately, 30 g of MCCII were hydrated, passed through a # 20 mesh sieve and spheronizated at frequencies of 6, 9 and 12 Hz and residence times of 15, 240 and 480 s in 9 experimental runs. In a separate experimental set, moisture levels of 25, 50, 75, 100 and 125% were employed at the optimal operating conditions of 6 Hz and 480 s. A microscopy analysis was used to evaluate the shape descriptors. Pellets properties such as compressibility, friability, porosity, strength, flow rate and mass were also evaluated.Results: Pellets having a small size and a high value of shape descriptors related to morphology were obtained employing a spheronization rate and spheronization time of 6Hz and 480s and 100% wetting level. The spheronization time increased pellet densification but decreased the total porosity. Pellet mass was also favoured by using high spheronization rates. A high moisture level (>100%) rendered pellets having a large size, mass, low porosity and good yield. Conversely, pellet size decreased as sample load increased, whereas porosity and compressibility increased as sample load augmented.Conclusion: MCCII offers the potential for use as an alternative pelletization agent rendering pellets having a good flowability, high mechanical strength and low friability at the optimal operational conditions.

English

The Y123, Y358 and Y257 bulk superconductors mixed with various ratio of non-superconducting Y211 (Y2BaCuO5) were synthesized by solid state reaction. The physical properties of pellets were investigated by d.c. four-probes measurement. The crystal structure was determined using powder X-ray diffraction and the characteristic peaks were determined using the Rietveld full-profile analysis method. Results showed that the Tconset and Tcoffset decreased with the increasing of Y211 doping. The samples consist of both superconducting phase and the non-superconducting phase. The lattice parameter of Y211 doped samples showed lower c direction than pure samples. The superconducting phase decreased with increasing Y211 content. The non-superconducting phases consists of Pccm (Ba2Cu3O6) and Im-3m (BaCuO2) respectively. According to the percentage of superconducting phase, the anisotropy was increased with Y211 contents.   Key words: Y-based superconductors, Y211, Rietveld method.

Effect of pelletizing conditions on combustion behaviour of single wood pellet

This paper presents how pelletizing die temperature and moisture content affect combustion behaviour of single wood pellet. Pine wood particles with two different moisture contents (i.e. 1wt.% and 12wt.%) were pelletized in a laboratory-scale single pelletizer (single die pellets) at die temperature of 20, 100, 150 and 200°C. The pellets were combusted in a laboratory scale furnace at 800°C. Time required for single pellet combustion generally increased with both increase of pelletizing temperature and moisture content of biomass. In addition, combustion behaviour of single die pellets was significantly different than those produced in a pilot scale pelletizing plant (semi-industrial scale pellet). That difference was due to variation in physical properties of pellets (e.g. density, and morphology).

Influence of CaO-SiO2-Al2O3 Ternary Oxide System on the Reduction Behavior of Carbon Composite Pellet: Part I. Reaction Kinetics

The reduction behavior of composite pellets comprising of hematite, synthetic graphite, and several oxide binder systems was investigated in a laboratory-scale horizontal tube furnace. Three oxide binder systems using silica-rich, alumina-rich, and conventional blast furnace slag compositions were selected to examine the effect of oxide chemistry on the reduction behavior of pellets. Compositional differences in the CaO-SiO2-Al2O3 ternary system were confirmed to influence the reactions occurring in composite pellets during the reduction of iron oxide. An in situ visualization approach was used to observe the oxide/iron/carbon interactions at high temperatures from 1623 K to 1773 K (1350 °C to 1500 °C). The off-gas composition was measured by means of an infrared analyzer to determine the pellet reaction rates. Changes in physical appearance during the in situ reaction experiments demonstrated a strong correlation between the oxide composition and internal reactions. Moreover, the mechanical properties of pellets were investigated by measuring compressive strength to understand the relationship between physical properties of pellets and the associated oxide binder systems selected for this study.

Compaction, compression and drug release properties of diclofenac sodium and ibuprofen pellets comprising xanthan gum as a sustained release agent

Compaction and compression of xanthan gum pellets were evaluated and drug release from tablets made of pellets was characterised. Two types of pellets were prepared by extrusion-spheronisation. Formulations included xanthan gum, at 16% (w/w), diclofenac sodium or ibuprofen, at 10% (w/w), among other excipients. An amount of 500 mg of pellets fraction 1000–1400 μm were compacted in a single punch press at maximum punch pressure of 125 MPa using flat-faced punches (diameter of 1.00 cm). Physical properties of pellets and tablets were analysed. Laser profilometry analysis and scanning electron microscopy of the upper surface and the surface of fracture of tablets revealed that particles remained as coherent individual units after compression process. Pellets were flatted in the same direction of the applied stress evidencing a lost of the original curvature of the spherical unit. Pellets showed close compressibility degrees (49.9% for pellets comprising diclofenac sodium and 48.5% for pellets comprising ibuprofen). Xanthan gum pellets comprising diclofenac sodium experienced a reduction of 65.5% of their original sphericity while those comprising ibuprofen lost 49.6% of the original porosity. Permanent deformation and densification were the relevant mechanisms of compression. Fragmentation was regarded as non-existent. The release of the model drug from both type of tablets revealed different behaviours. Tablets made of pellets comprising ibuprofen released the model drug in a bimodal fashion and the release behaviour was characterised as Case II transport mechanism (release exponent of 0.93). On the other hand, the release behaviour of diclofenac sodium from tablets made of pellets was anomalous (release exponent of 0.70). For the latter case, drug diffusion and erosion were competing mechanisms of drug release.

Effect of drying rate on porosity and tabletting behaviour of cellulose pellets

The purpose of this study was to investigate the effect of drying rate during static drying on certain physical properties of pellets. Pellets were prepared from microcrystalline cellulose by granulation with different agglomeration liquids (various ethanol/water ratios) and thereafter dried without agitation at different drying rates. The dry pellets were characterised with respect to their shape, porosity, and compression shear strength and the tensile strength of tablets formed from pellets with low and high drying rates was determined. Drying of the pellets occurred at a falling rate and the reduction in liquid content with time obeyed a first order type of relationship. An increased drying rate did not affect the shape and surface texture of the dried pellets and did not cause them to fracture. However, the drying conditions did affect pellet porosity, with an increased drying rate resulting in more porous pellets. Through a relationship with pellet porosity, the drying rate also affected the deformability of the pellets (as assessed from Kawakita 1/ b values) and their ability to form tablets. Owing to a strong effect of porosity on pellet compactability, marked changes in tablet tensile strength with variations in drying rate may be obtained.

Quantitative evaluation of kneading and extrusion processes by pressure transmission characteristics of wet kneaded masses

This study is devoted to the quantitative evaluation of wet kneaded masses prepared by a paddle-type kneader, and the analysis of the kneading process and the following extrusion granulation process. A compaction tester of wet kneaded masses has been developed and the compression properties of the masses are characterized by a pressure transmission between the upper and lower punches of the tester. The dispersion condition of a binder liquid among the wet kneaded masses prepared under various kneading times is investigated. The extrusion pressure through a single ejection hole on the lower punch is also measured. The pressure transmission is found to have a linear relationship between the dispersion of binder liquid and the extrusion pressure. This results lead to a conclusion that the proposed method provides the generalized measuring means of wet kneaded masses. An extrusion granulation by a dome-type extruder is conducted using wet kneaded masses and physical properties of the extruded pellets (granules), such as friability, specific surface area and disintegration time, are investigated. Good linearity can be found between the pressure transmission and the physical properties of the pellets. As the result of these findings, the kneading condition, i.e. the dispersion of binder liquid among the wet kneaded masses, can be quantitatively analyzed and the physical properties of pellets prepared by extrusion granulation can be accurately predicted by the pressure transmission measured by the newly developed compression tester.

Extrusion/spheronization--effect of moisture content and spheronization time on pellet characteristics.

As part of a larger effort aimed at optimizing the properties of pellets produced by spheronization of extruded masses, the effect of the moisture content of wet masses on extrusion force and torque was studied. The wet masses were composed of either microcrystalline cellulose (MCC) or mixtures of MCC with lactose or dicalcium phosphate. Based on the force and torque data, a moisture content "window" was defined for consistent extrusion. Moisture exerts a lubricant effect, and a moisture level of 100-120% w/w dry solid seemed necessary for the extrusion of MCC into rod-shaped, discrete pieces. Screen force clearly depended on the moisture content but was relatively insensitive to extruder speed, especially at 80% and 100% moisture content. The physical properties of pellets as a function of spheronization time were studied by sampling the material at known intervals. The percent yield, tapped density, and a two-dimensional sphericity index of an 18/20 mesh fraction of pellets were measured. Maximum yield, tapped density, and sphericity were achieved within 60 sec in the spheronizer. With increasing residence time, the shape and density were unchanged while the yield was severely reduced. Among the formulations studied, pellets with equal amounts of lactose and MCC were superior to those of pure MCC in yield, density, and sphericity. Based on these results, an outline to optimize the endpoint of the spheronization process for formulations containing MCC is suggested.

Variations of physical properties in pellets containing magnesium during calcination and sulfation

Physical properties of pellets containing magnesium before and after either calcination or sulfation were determined, respectively. The physical properties studied were pore surface area, porosity and pore size distribution. The experimental results indicated that surface area, porosity and pore size of the solid samples were increased due to calcination but reduced due to sulfation. The differences in pore surface area and porosity were found to be determined by the calcination temperature, calcination time and sulfation temperature. The dependence of pore size distribution on those treatments was found to be insignificant.

Evaluation of Drug Layering and Coating: Effect of Process Mode and Binder Level

Top-spray layering and Wurster coating are common techniques for layering and coating operations, respectively. In the present study, the efficiency of these techniques was compared with rotolayering and rotocoating in the Niro-Aeromatic MP-1 Rotoprocessor. Also, three different polymers were evaluated as binding agents in the layering procedure. A solution containing drug and a suitable binder was layered onto nonpareil seeds followed by coating with a water-insoluble polymer. The pellets were evaluated for physical properties, surface characteristics and drug content (assay). The process efficiency was evaluated from process time, assay, and SEM data of the pellets. Efficiency of layering was compared between toplayering and rotolayering processes while efficiency of coating was compared between Wurster coating and rotocoating processes. The physical properties of pellets were used to explain the influence of binder nature and level of use in the layering process.