Pellet Moisture Research Articles

Modeling and analysis of pelletization process based on a multi-hole pelletizing device

A multi-hole pelletizing device (MPD) was proposed to simulate the granular extrusion process of animal feed due to its cheap, fast, and controllable features. The compression mechanism was analyzed and discussed according to the compression force-time curve. This study applied response surface methodology (RSM) with a central composite design (CCD) to develop predictive models for the compression force Fout and the pellet properties which includes pellet density ρp, pellet moisture content Mcp, and pellet tensile strength Dp based on the MPD. The effects of feedstock moisture content Mcf (10%-18% w.b.), feedstock particle size Sf (8 meshes -24 meshes), die temperature Td (70°C-110°C) and compression speed Vc (5 mm/min to 25 mm/min) were investigated. Response surface models developed for the compression force and pellet properties have adequately described the pelleting process (R2 >0.95). The results showed the significant effects of all factors and most of the squared and interaction terms on the compression force and pellet physical properties. It can be concluded from the present study that moisture content and die temperature, followed by compression speed and feedstock particle size are the interacting process factors influencing compression force and pellet properties. Keywords: animal feed, pelletization, modeling, compression force, response surface methodology, analysis of variance DOI: 10.25165/j.ijabe.20191201.3264 Citation: Jiang Q H, Wu K, Sun Y. Modeling and analysis of pelletization process based on a multi-hole pelletizing device. Int J Agric & Biol Eng, 2019; 12(1): 17–23.

Particle Size Distribution and Physicochemical Properties of Pellets Made of Straw, Hay, and Their Blends

The aims of the study were (a) the determination of the physicochemical characteristics of properties of pellets made of shredded residue from hay, wheat straw, and their blend at a ratio of 50:50, and (b) the determination of a mathematical model of pellet durability, using a response surface method. Tests were conducted according to applicable standards. As a result of thermal changes during the pressure agglomeration process, the material moisture content of pellets had slightly decreased versus raw three biomasses by 0.50% w.b. (wet basis) to a final value within the range of 5.56–5.87% w.b. The pellet properties of the blend were not adequately represented by the arithmetic mean of their components. Pellets made of hay, straw, and their blend, had DM (DM—dry matter) specific densities of 1034, 974, and 1102 kg m−3, respectively. The densities showed correlation with calorific values (r = 0.637), which were in the range of 16.07–17.00 MJ kg−1. The pellet durability coefficient correlated negatively with particle size and biomass moisture content. On the basis of previous conclusions, a non-linear mathematical model was formulated to account for the pellet durability coefficient relative to pellet moisture, and the relation of particle sizes and specific density to pellet bulk density.

Preparation of core-shell iron ore-biochar composite pellets for microwave reduction

Due to its high carbon and low impurities contents, as well as good reactivity, biochar can partly or totally replace coal or coke as a promising reducing agent in metallurgy. This study offers a new method to produce qualified metallized pellets for steelmaking after microwave-assisted self-reduction of iron ore-biochar composite pellets. The key point was to prepare green composite pellets with good quality indexes which also allowed sufficient self-reduction under microwave irradiation. For this purpose, core-shell iron ore-biochar composite pellets were prepared with inhomogeneous biochar distribution. It was found that high grade iron concentrates A and B could be used together for improving pelletizing. Controlling the distributions and proportions of iron concentrate B (different additions in the core and shell) and biochar (all located in the core of the pellets) would contribute to high-quality iron ore-biochar green composite pellets with the drop number of 3.6 times/0.5 m, compressive strength of 11.1 N/p, and decrepitation temperature of 410 °C under the pelletizing conditions of total proportion of iron concentrate B of 30%, pelletizing time of 16 min, rotation speed of 25 r/min, bentonite dosage of 2.3%, C/Fe mass ratio of 0.225, pellet moisture content of 13.0%, and proportions of iron concentrates A and B in the shell of 10% and 0%, respectively. The subsequent microwave reduction tests showed that the core-shell metallized pellets with the total iron content and metallization degree of 89.15% and 95.52%, respectively, could be obtained after microwave reduction at 1050 °C for 30 min under N2 atmosphere. They had better reduction indexes than those produced from the pellets with homogeneous structure, serving as a good burden for steelmaking directly.

CARACTERÍSTICAS FÍSICAS, MICROESTRUCTURALES Y SENSORIALES DEALIMENTOS BOTANA EXTRUDIDOS EXPANDIDOS POR MICROONDASADICIONADOS CON CALABAZA DESHIDRATADA

The objective of this work was to study the effects of the extrusion temperature (T, 93-141 °C), feed moisture content (FMC, 21.27-34.73%), and dehydrated squash content (DS, 0.43-15.57%) on physical, microstructural and sensory characteristics of microwave-expanded snack foods (SF) formulated adding dehydrated squash to a base blend of corn starch-yellow corn. A second order rotatable central composite design and the response surface methodology for data analysis were used. The T and FMC showed a greater effect (P < 0.05) on specific volume and moisture of pellets, whereas FMC and DS showed a greater effect on Chroma (C*) and Hue (H*) color parameters. The microstructural properties of the snacks evaluated with the Rapid Visco-Analyzer (RVA), Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were related mainly to the starch gelatinization. Also, the sensory acceptability of snacks added with DS reached almost 79%. The results indicate that it is possible to elaborate SF with acceptable physical and sensory characteristics by adding DS to a base blend.

114 Evaluation of Using Hand Held Near Infrared Spectroscopy for Pellet Fines and Moisture.

Recently the use of Near Infra-red Reflectance spectroscopy (NIR) to predict nutritional information has grown. The ability to predict chemical information around protein, oil, and carbohydrates in real time has enabled nutritionists to make decisions around feeding values and to better predict animal performance. What is generally overlooked is that NIR can be used to predict physical as well as chemical properties. In addition new NIR equipment particularly at the portable end of the market has been introduced which allows the user to get closer to the production line and to make decisions whilst the product is still in process. One such physical attribute, pellet fines, is well established as resulting in poorer FCR especially if feeder adjustment is not closely controlled leading to an increased cost of pig production. The aim of the study was to determine if using a hand held (HH) NIR instrument it is possible to determine the percent pellet fines as measured using a standard sieve methodology. This trial was set-up to measure pellet fines on 89 swine feed samples using the 2 pan sieve method and developing a calibration to determine if it is feasible to measure particle size by HH-NIR. In addition 29 samples were sent for wet chemistry analyses for moisture; this data was used to determine if the level of moisture can be predicted by NIR. Using a HH-NIR instrument (wavelength between 920nm to 1650nm) approximately 1.2 to 2.0 kg of feed sample was placed in a specialized box and scanned at 5 different locations collecting 200 spectra per scan. The resulting 1000 spectra were averaged to produce 1 spectrum per sample. The same sample was then measured by being placed on to the sieve (#6) with the pan attached to the bottom. The sieve was then shaken for 45 seconds and repeated for 15 seconds until the sample was completely sieved. Pellets and fines were then weighed and the % fines determined. Chemometric analyses showed that there was a strong calibration between pellet fines analysis and the NIR spectra (r2 = 0.93, SEP 3.1). Furthermore using a standard feed calibration provided by Aunir for this HH-NIR it showed that there is a good prediction of pellet moisture against the laboratory values (r2 = 0.93, SEP 0.708). Overall, these results confirm that HH-NIR can be used at the mill to determine pellet fines and pellet moisture.

The Dispersal of Rodent-Borne Strains ofAphanoascus KeratinophilusandChrysosporium Tropicumby Pellets of Predatory Birds

The species composition of keratinophilic fungi in 153 pellets of nine species of predatory birds was analysed. Based on morphological criteria, a total of 439 strains of non-dermatophytic fungi of the Chrysosporium group were isolated and identified. Dermatophytes were not detected. The collection was verified using molecular methods, such as PCR-RFLP (restriction fragments length polymorphism) and two potentially pathogenic species, Aphanoascus keratinophilus and Chrysosporium tropicum, were detected. Pellet colonisation by these fungi ranged between 37.5% and 91.7% depending on the bird species. As the analysis of undigested remains found in the pellets showed, rodents, mostly Microtus, which constituted from 57% to 100% of the birds’ diet, were a chief source of A. keratinophilus and Ch. tropicum strains. It was demonstrated that the survival and dispersal of A. keratinophilus strains was supported by higher pellet moisture while those of Ch. tropicum strains by drying, which was conditioned by the site where pellets were dropped and deposited by individual species of predatory birds. Based on the results, circulation routes of both opportunistic pathogens using pellets of predatory birds as carriers are proposed.

Applicability of near-infrared spectroscopy in the monitoring of film coating and curing process of the prolonged release coated pellets

Although process analytical technology (PAT) guidance has been introduced to the pharmaceutical industry just a decade ago, this innovative approach has already become an important part of efficient pharmaceutical development, manufacturing, and quality assurance. PAT tools are especially important in technologically complex operations which require strict control of critical process parameters and have significant effect on final product quality. Manufacturing of prolonged release film coated pellets is definitely one of such processes. The aim of the present work was to study the applicability of the at-line near-infrared spectroscopy (NIR) approach in the monitoring of pellet film coating and curing steps. Film coated pellets were manufactured by coating the active ingredient containing pellets with film coating based on polymethacrylate polymers (Eudragit® RS/RL). The NIR proved as a useful tool for the monitoring of the curing process since it was able to determine the extent of the curing and hence predict drug release rate by using partial least square (PLS) model. However, such approach also showed a number of limitations, such as low reliability and high susceptibility to pellet moisture content, and was thus not able to predict drug release from pellets with high moisture content. On the other hand, the at-line NIR was capable to predict the thickness of Eudragit® RS/RL film coating in a wide range (up to 40μm) with good accuracy even in the pellets with high moisture content. To sum up, high applicability of the at-line NIR in the monitoring of the prolonged release pellets production was demonstrated in the present study. The present findings may contribute to more efficient and reliable PAT solutions in the manufacturing of prolonged release dosage forms.

Method to Produce Durable Pellets at Lower Energy Consumption Using High Moisture Corn Stover and a Corn Starch Binder in a Flat Die Pellet Mill

A major challenge in the production of pellets is the high cost associated with drying biomass from 30 to 10% (w.b.) moisture content. At Idaho National Laboratory, a high-moisture pelleting process was developed to reduce the drying cost. In this process the biomass pellets are produced at higher feedstock moisture contents than conventional methods, and the high moisture pellets produced are further dried in energy efficient dryers. This process helps to reduce the feedstock moisture content by about 5-10% during pelleting, which is mainly due to frictional heat developed in the die. The objective of this research was to explore how binder addition influences the pellet quality and energy consumption of the high-moisture pelleting process in a flat die pellet mill. In the present study, raw corn stover was pelleted at moistures of 33, 36, and 39% (w.b.) by addition of 0, 2, and 4% pure corn starch. The partially dried pellets produced were further dried in a laboratory oven at 70 °C for 3-4 hr to lower the pellet moisture to less than 9% (w.b.). The high moisture and dried pellets were evaluated for their physical properties, such as bulk density and durability. The results indicated that increasing the binder percentage to 4% improved pellet durability and reduced the specific energy consumption by 20-40% compared to pellets with no binder. At higher binder addition (4%), the reduction in feedstock moisture during pelleting was <4%, whereas the reduction was about 7-8% without the binder. With 4% binder and 33% (w.b.) feedstock moisture content, the bulk density and durability values observed of the dried pellets were >510 kg/m3 and >98%, respectively, and the percent fine particles generated was reduced to <3%.

Method to Produce Durable Pellets at Lower Energy Consumption Using High Moisture Corn Stover and a Corn Starch Binder in a Flat Die Pellet Mill.

A major challenge in the production of pellets is the high cost associated with drying biomass from 30 to 10% (w.b.) moisture content. At Idaho National Laboratory, a high-moisture pelleting process was developed to reduce the drying cost. In this process the biomass pellets are produced at higher feedstock moisture contents than conventional methods, and the high moisture pellets produced are further dried in energy efficient dryers. This process helps to reduce the feedstock moisture content by about 5-10% during pelleting, which is mainly due to frictional heat developed in the die. The objective of this research was to explore how binder addition influences the pellet quality and energy consumption of the high-moisture pelleting process in a flat die pellet mill. In the present study, raw corn stover was pelleted at moistures of 33, 36, and 39% (w.b.) by addition of 0, 2, and 4% pure corn starch. The partially dried pellets produced were further dried in a laboratory oven at 70 °C for 3-4 hr to lower the pellet moisture to less than 9% (w.b.). The high moisture and dried pellets were evaluated for their physical properties, such as bulk density and durability. The results indicated that increasing the binder percentage to 4% improved pellet durability and reduced the specific energy consumption by 20-40% compared to pellets with no binder. At higher binder addition (4%), the reduction in feedstock moisture during pelleting was <4%, whereas the reduction was about 7-8% without the binder. With 4% binder and 33% (w.b.) feedstock moisture content, the bulk density and durability values observed of the dried pellets were >510 kg/m3 and >98%, respectively, and the percent fine particles generated was reduced to <3%.

Yeast as a Bioremediation Nanoparticle Agent in Piggery-Digested Wastewater Treatment

Abstract The opportunity to produce algal biofuel cost-effectively from waste materials, such as piggery-digested waste, drives research to optimize piggery waste effluent as an algal growth medium. Therefore, the aim of this study was to investigate the potential of newly isolated wastewater-born yeast to optimize growth parameters and maximize pollutant degradation in digested wastewater bioremediation. One isolate was identified as Galactomyces geotrichum through morphological observation and DNA sequencing. Growth parameters regarding pH, temperature, and inoculum amount were optimized by orthogonal design to maximize pollutant removal. Results showed that optimal growth conditions were pH 6, 25°C, and 2.5 g mycelium pellet moisture weight. Chemical oxygen demand (COD) reached 60% and total phosphorus (TP) reduction reached 45% under these conditions. Our observations demonstrate that pH had an overall significant effect on COD and TP reduction. More importantly, results suggested that pretreatment wi...

Specific energy consumption and quality of wood pellets produced using high-moisture lodgepole pine grind in a flat die pellet mill

In the present study a Box–Behnken experimental design was used to understand the effect of the moisture content of lodgepole pine grind (33–39%, w.b.), die speed (40–60Hz) and preheating temperature (30–90°C) on the pellet quality and specific energy consumption. The partially dried pellets produced had high-moisture content in the range of 19–28% (w.b.), and were further dried to <9% (w.b.) in a mechanical oven set at 70°C for 3h. Dried pellets were further evaluated for pellet moisture content, unit, bulk, tapped density, and durability. Response surface models developed for the product properties have adequately described the process based on coefficient of determination values. Surface plots developed indicated higher unit, bulk, and tapped density (1050, 520, 560kg/m3) are achievable at 33–35% (w.b.) moisture content of the lodgepole pine grind, die speed of 60Hz and preheating temperature of 30–60°C. Higher moisture content of 39% (w.b) reduced unit, bulk, and tapped density to <912, 396, and 452kg/m3. Higher durability values of >95% were obtained at 33–35% (w.b.) at lower preheating temperatures of 30–50°C and higher die speed of >50Hz. At 33% (w.b.) moisture content of the lodgepole pine grind, preheating temperature of 90°C, and die speed of 60Hz, the observed specific energy consumption was <116kWh/ton. Scanning electron microscope studies indicated that lignin crosslinking is the primary reason for binding of the lodgepole pine grind at high-moisture content.

Cassava Stem Powder as an Additive in Biomass Fuel Pellet Production

In biomass fuel pelletizing, some raw materials with less favorable binding properties require a binding enhancing additive for enhancing required pellet quality. Starch is commonly used as a binder in industrial fuel pelletizing but is a refined product that adds substantially to pellet production costs. In this study, finely milled cassava stems, a starch-rich, cheap, and underutilized byproduct from food production, were used and compared to refined starch as an additive in biofuel pellet production. The evaluation was performed in an experimental design with the factors cassava stem/starch content, moisture content, and material temperature. Measured responses were pellet bulk density, mechanical durability, amount of fines, pelletizer motor current, coefficient of variance for pelletizer motor current, CVA (a measure of process stability), pellet temperature, die temperature, and pellet moisture. Each response was modeled by multiple linear regression (MLR). Cassava stem addition gave similar effects...

Emissions from sawdust in packed moving bed dryers and subsequent pellet production

ABSTRACTThis study quantifies emissions of hydrocarbon terpenes from the drying of sawdust in packed moving bed dryers, through the production chain to the finished pellets, and determines the parameters suitable for emission control. The terpene content in softwood sawdust and pellets was analyzed using gas chromatography. The distribution of VOC emissions over the bed was measured with a flame ionization detector. After drying, 30–40% of the initial terpenes remain in the wood, 20–30% remain after grinding, and 10–15% remain after pelleting. Dryer emissions correlate with residence time and final sawdust moisture content. Pellet press emissions correlate with pellet moisture content.

Effect of process variables on the density and durability of the pellets made from high moisture corn stover

A flat die pellet mill was used to understand the effect of high levels of feedstock moisture content in the range of 28–38% (w.b.), with die rotational speeds of 40–60 Hz, and preheating temperatures of 30–110 °C on the pelleting characteristics of 4.8 mm screen size ground corn stover using an 8 mm pellet die. The physical properties of the pelletised biomass studied are: (a) pellet moisture content, (b) unit, bulk and tapped density, and (c) durability. Pelletisation experiments were conducted based on central composite design. Analysis of variance (ANOVA) indicated that feedstock moisture content influenced all of the physical properties at P 0.88. The other pellet quality attributes such as unit, bulk, tapped density, were maximised at feedstock moisture content of 30–33% (w.b.), die speeds of >50 Hz and preheating temperature of >90 °C. In case of durability a medium moisture content of 33–34% (w.b.) and preheating temperatures of >70 °C and higher die speeds >50 Hz resulted in high durable pellets. It can be concluded from the present study that feedstock moisture content, followed by preheating, and die rotational speed are the interacting process variables influencing pellet moisture content, unit, bulk and tapped density and durability.

The Effect of External Conditions on Ignition Temperature of Thermoplastic Polyurethane Elastomers

The paper reports a study of the impact of moisture and age of pellets, as well as an external condition, on the thermal degradation of the thermoplastic polyurethane elastomers. Because thermoplastic polyurethane elastomers are hydroscopic polymer, moisture will have a significant impact on thermal degradation. For determination of the effect of moisture and age were used the thermo gravimetric analysis, differential scanning calorimeter and ISO STN 871: Plastics. Determination of ignition temperature using a hot-air furnace.

The bonding/strengthening mechanism of colemanite added organic binders in iron ore pelletization

The addition of boron compounds into pellet mix is proposed as a potential solution to overcome the insufficient compressive strengths of preheated and fired pellets produced with organic binders. Colemanite was tested as an alternative binder to bentonite either alone or in combination with some organic binders on magnetite pellets. The performances of the tested binders on pellet qualities: balling, wet pellet moisture content, drop number, compressive strengths and microstructure of pellets have been compared with the performances of reference bentonite binders. The results of the tests showed that the qualities of pellets are insufficient when organic binders and colemanite are used as binders alone. The former failed to provide sufficient preheated and fired pellet strengths, the latter failed in terms of wet and dry pellet quality. However, good quality wet, dry, preheated and fired pellets could be produced with the combination of these two binders. In addition, stronger pellets could be produced at lower firing temperatures like 1373K thanks to addition of colemanite. The bonding mechanism of colemanite containing pellets was examined by scanning electron microscopy. It was found that the improved preheated and fired compressive strengths of colemanite-added pellets were due to the physical melting of colemanite at the contact point of magnetite grains during thermal treatment.

Effect of process variables on the quality characteristics of pelleted wheat distiller's dried grains with solubles

The rapid expansion of ethanol processing plants in Canada has resulted in a significant increase in the production of wheat-based distiller's dried grains with solubles (DDGS). Transportation and flowability problems associated with DDGS necessitate investigations on pelleting. In the present study, the effect of process variables like die temperature (T) and feed moisture content (Mw) on the pellet properties like pellet moisture content, durability and pellet density was explored using a single pelleting machine; further studies on pelleting DDGS using a pilot-scale pellet mill were also conducted to understand the effect of die diameter and steam conditioning on durability and bulk density of pellets. Proximate analysis of DDGS indicated that crude protein and dry matter were in the range of 37.37–40.33% and 91.27–92.60%, respectively. Linear regression models developed for pellet quality attributes like pellet moisture content, pellet density and durability adequately described the single pelleting process with R2 value of 0.97, 0.99 and 0.7, respectively. ANOVA results have indicated that linear terms T and Mw and the interaction term T × Mw were statistically significant at P < 0.01 and P < 0.1 for pellet moisture content and pellet density. Based on the trends of the surface plots, a medium T of about 50–80 °C and a low Mw of about 5.1% resulted in maximum pellet density and durability and minimum pellet moisture content. Results from pilot-scale studies indicated that bulk density, durability and throughput values were 436.8–528.9 kg m−3, 60.3–92.7% and 45.52–68.77 kg h−1, respectively. It was observed that both die diameter and steam addition had a significant effect on the bulk density and the durability values. The highest bulk density and durability were achieved with 6.4 mm die diameter with steam addition compared to 7.9 mm die with or without steam addition.

The influence of raw material characteristics on the industrial pelletizing process and pellet quality

Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 × 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 × 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 × 21 data matrix of fatty- and resin acid concentrations measured by GC–MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality.

Prediction of Iron Ore Pellet Strength Using Artificial Neural Network Model

Cold Compression Strength (CCS) is an important property of iron ore pellets that are used for the production of DRI from shaft furnace or for use in blast furnace. CCS is one of the control parameters during the pellet production and it is supposed to be closely monitored to control the process. In order to develop control-strategy, an Artificial Neural Network model has been developed to predict CCS of pellets in straight grate indurating machine from 12 input variables viz. feed rate of green pellets, bed height, burn through temperature, firing temperature, specific fuel gas consumption; bentonite, moisture and carbon content in green pellets; Al2O3, MgO, basicity and FeO in fired pellets. CCS was found to be more sensitive to variation in Bentonite, basicity, FeO and Green pellet moisture. Generalized Feed Forward neural network with back propagation error correction technique was successfully used to predict the CCS. The predicted results were in good agreement with the actual data with less than 3% error.

STORAGE AND HANDLING CHARACTERISTICS OF PELLETS FROM POULTRY LITTER

Poultry litter (combination of accumulated manure and bedding materials) was pelleted through a 3/16-in.(4.76-mm) diameter die. The storage and handling properties of the pellets were measured within a moisture range of 6.0%and 22.0% (w.b.). Bulk density and particle density of the pelleted litter respectively decreased and increased with increasein moisture content. The force required to rupture the pellets varied from 316 N at 6.0% moisture content to 68 N at 22.0%w.b. Durability of the pellets were also affected by moisture content. Pellet moisture absorption rates were significantly (P <0.05) affected by air relative humidity. The values of thermal conductivity, thermal diffusivity and specific heat for the pelletswere respectively obtained to be 0.264W/m K, 2.67 . 10-7 m2/s, and 1265.6 J/kg K.