Feed Screw Research Articles

Gasification process of palm kernel shell to fuel gas: Pilot-scale experiment and life cycle analysis

This research demonstrates a palm kernel shell gasification system for producing fuel gas, also known as producer gas. Using air as an oxidant, the gasification process converts palm kernel shells into fuel gas which contains combustible gases, such as hydrogen, carbon monoxide, and methane with nitrogen dominating the composition of the gas. This fuel gas can supply heat via direct combustion or generate electricity for fossil fuel substitution of an internal combustion engine. As a biomass-derived gas, the fuel gas is characterized as carbon-neutral inherently. During the conversion process, the system needs electricity to power the screw feeder, air blowers, and cooling-water pumps, and to rotate the gasifier's bottom plate to take the char out. Based on the experiments, mass balance, and energy balance calculations, this study examines the global warming, acidification, and eutrophication potential using the openLCA v1.10.3 software and Environmental Footprint (MID-Point indicator) database for impacts assessment when the system is operated in Indonesia and Malaysia with various electricity sources. It is found that the feedstock contributed most of the global warming potential and eutrophication potential, while the electricity dominated the acidification potential. This study recommends operation at a lower equivalent ratio to reduce environmental impacts.

Study on the importance of bed shape in combined DEM-CFD simulation of fixed-bed Biomass gasifiers

The extensive utilization of fossil fuels is limited by the environmental problems related to carbon dioxide and other greenhouse gas emissions. As a result, the generation of energy and heat from biomass has become increasingly economically and ecologically important in recent decades. In existing numerical studies, the effect of slope form on airflow within the biomass gasifier was not systematically investigated. To explore the potential impact of the real shape of a fuel bed on local gasification conditions, a small-scale updraft fixed-bed gasifier was modeled in this study with a default lateral feeding position and air supply from below. The discrete element method (DEM) was combined with computational fluid dynamics (CFD) by using two open-source software: LIGGGHTS® and OpenFOAM®. The particle models of two biomasses (olive stone and almond shells) were calibrated and used to investigate qualitatively and quantitatively the airflow patterns, including the resulting uneven pressure and temperature distribution at/over the slope surface. Besides, the effects of operating parameters of the feeding system on slope form were highlighted. Therefore, the real fuel heap shape should be taken into consideration for future simulation studies on side-fed, fixed bed gasifiers. • Material models for DEM simulation are calibrated and validated. • The influences of heap shape and inlet air velocity are explored comprehensively. • Quantitative discussion on the rates of temperature and pressure change. • Suggests that different screw feeding speeds can realize dynamic combustion optimization. • Limitations of a particular DEM-CFD co-simulation model are addressed.

Research on displacement fluctuation reduction for hydrostatic lead screw feed system at low-speed operation under variable loads

This study proposes a method to reduce the displacement fluctuation of hydrostatic lead screw feed systems under ultralow velocity and subjected to different loads by means of a dual-drive hydrostatic screw-nut pair (DDHSNP). The differential compound principle of DDHSNP and the wedge-shaped oil film gap are used to generate the hydrodynamic effect of lubricating film while ensuring the worktable is fed at extremely low speed. After that, the model of the DDHSNP, considering the pitch errors and nut posture errors, is established based on the equation of motion, the Reynolds equation, and the Euler equation. Finally, a comparative experiment is conducted to demonstrate the effectiveness of the proposed method. The results indicate that: (a) The nut's posture errors have little effect on the displacement fluctuation of the hydrostatic lead screw feed system. (b) The DDHSNP can significantly reduce the displacement fluctuation of the hydrostatic lead screw feed system under variable loads and low speeds. This research is an excellent improvement for the superior motion characteristics of the hydrostatic lead screw at low speed.

Effect of Extrusion on the Functional, Textural and Colour Characteristics of Texturized Hempseed Protein

The search for allergy friendly texturized vegetable proteins (TVP) has prompted the use of novel protein sources over conventional wheat and soy proteins. Hempseed protein (HP) offers promising nutritional characteristics. This work assessed the effect of feed moisture content (FMC) and screw rotation speed (SRS) on the textural, functional and colour characteristics of texturized HP. The HP was extruded using a co-rotation twin screw extruder at 30–60% FMC and 200–400 rpm SRS. Results showed that significant differences were observed from FMC, SRS and the interaction of FMC and SRS on the product expansion index, integrity index, water and oil absorption capacity (WAC and OAC), some texture profile parameters and colour characteristics. Decreasing FMC and increasing SRS tended to increase the texturization index, expansion index, WAC, OAC, integrity index and texture profile characteristics but decrease density, L* and b* values. These results contribute to our understanding of the properties of texturized HP which are important for application in food industry.

Effect of extrusion processing conditions on the techno-functional, antioxidant, textural properties and storage stability of wholegrain-based breakfast cereal incorporated with Indian horse chestnut flour

The central composite rotatable design was used to plan the experiments using feed moisture (FM) content, barrel temperature (BT), screw speed (SS), and concentration of Indian horse chestnut flour (IHCF) as process variables varied between 10–18%, 70–150°C, 290–380 rpm and 1.75–4.75%, respectively. Surface mechanical energy, water holding capacity, swelling volume, piece density, longitudinal expansion, water activity and colour attributes were used as response variables. The whole grain flours added with 2.5% IHCF and extruded at 12% FM, 130°C BT and 380 rpm SS produced optimum quality breakfast cereals with 0.713 desirability. Extrudates packed in aluminum pouches were found to be suitable packaging materials and were shelf-stable for 6 months with better quality retention.

Importance of Feedstock in a Small-Scale Agricultural Biogas Plant

Although no legal sustainability criteria have been formulated for electricity and heat production from biogas, the sustainability and profitability of large-scale biogas plants which use mainly energy crops is now questioned. Small (farm-size) biogas plants characterized by CHP electrical output in the range between 15 kWel and 99 kWel, operating on agricultural wastes and by-products, seem more suitable; however, the variety of feedstock may be crucial in the proper design and operation of such family biogas plants. This paper aims to present the problems that occurred in small agricultural biogas plants fed with sheep manure (SM), horse manure (HM), and grass-clover silage (GCS). This paper also focuses on analyzing the energy balance and carbon dioxide (CO2) emissions related to four technological solutions (Scenarios 1–4) based on various feedstocks, grinding and feeding systems, and wet/dry fermentation. The biogas plant was originally based on dry fermentation with an organic loading rate ~10.4 kgVS·m−3·d−1, a hydraulic retention time of 16 days, and temperature of 45 °C in the fermentation chamber. The material was shredded and mixed in a mixing device, then the mixture of manures and silage was introduced to the horizontal fermentation chamber through a system of screw feeders. The biogas and the digestate were collected in a reinforced concrete tank. The biogas was sent to the CHP unit of an installed electrical power of 37 kWel, used to produce electricity and recover the heat generated in this process. Scenario 1 is based on the design assumptions used for the biogas plant construction and start-up phase. Scenario 2 includes a new feeding and grinding system, in Scenario 3 the feedstock is limited to SM and HM and wet fermentation is introduced. In Scenario 4, a dry fermentation of SM, HM, and maize silage (MS) is assumed. Avoided CO2 emissions through electricity and heat production from biogas were the highest in the case of Scenarios 1 and 4 (262,764 kg CO2·y−1 and 240,992 kg CO2·y−1) due to high biogas production, and were the lowest in Scenario 3 (7,481,977 kg CO2·y−1) because of the low specific methane yield (SMY) of SM and HM. Nevertheless, in all scenarios, except Scenario 3, CO2 emissions from feedstock preparation and biogas plant operation are much lower than that which can be avoided by replacing the fossil fuel energy for the electricity and heat produced from biogas. Our observations show that a small agricultural biogas plant can be an effective energy source, and can contribute to reducing CO2 emissions only if the appropriate technological assumptions are adopted, and the entire installation is designed correctly.

Gain scheduling control of ball screw feed drives based on linear parameter varying model

Gain scheduling control of ball screw feed drives based on linear parameter varying model

Twin-Screw Continuous Mixing Can Produce Dry Powder Inhalation Mixtures for Pulmonary Delivery

The feasibility of twin-screw corotating extruder as a continuous process mixer to prepare dry powder inhalation (DPI) powders was investigated. Interactive mixtures of 1% micronized budesonide, 0.3% magnesium stearate and 98.7% alpha-lactose monohydrate were manufactured using a Leistritz Nano-16 extruder at various processing conditions. One set of GFM (grooved mixing) elements were included in the screw profile to provide distributive mixing of conveyed powders with the goal of resulting in a homogeneous mixture. Residence time in the twin-screw mixer was modelled to quantify mixing efficiency. Comparative powders were also prepared using either low or high-shear batch mixing to compare the effect of mixing methods on the properties of the budesonide dry powder inhalation formulation. Twin screw mixing results in homogeneous mixtures with aerosol performance comparable to that of high-shear batch mixing. Scanning electron microscopy confirmed that twin screw mixing produces particles with morphology like that of low and high-shear batch mixing. X-ray diffraction (XRD) analysis verified that there was no form change of the drug due to twin-screw processing. Statistical regression was used to probe the relationship between twin screw mixing process parameters such as screw speed and feed rate and aerosol performance. The twin screw mixing process was found to be robust, as no significant differences in aerosol performance were found for various processing parameters.

Correlation analysis between extrusion process variables and quality of purslane leaf powder rice extrudates.

Extrusion has become one of the most popular techniques in food processing, and the process parameters are closely related to product quality. Purslane (Portulaca oleracea L.) can be used in medical and food products as a vegetable and herb. It has limited application in extrusion. The effects of extrusion process variables (screw speed, barrel temperature, and feed moisture) on system variables (specific mechanical energy [SME], die head pressure, and torque) and target variables (water absorption index, water solubility index, iodine blue value, color, pasting properties, and textural properties) of purslane powder compound rice were studied. The results showed that SME was moderately positively correlated with screw speed (r=0.608, p<0.05). However, torque was moderately negatively correlated with feed moisture (r=-0.574, p<0.05), and die head pressure was moderately negatively correlated with barrel temperature (r=-0.635, p<0.01). The target variables of extrudates were also correlated with the system parameters to varying degrees. These results are helpful to control and predict the texture, pasting properties, and other quality characteristics of extruded products containing purslane powder. PRACTICAL APPLICATION: The results showed that torque and die head pressure were moderately negatively related to barrel temperature, specific mechanical energy was moderately positively related to screw speed, peak viscosity and breakdown viscosity were moderately negatively related to specific mechanical energy, and water absorption index was moderately negatively related to torque and die head pressure. It provides a reference for the research of influencing system parameters and changing product quality by controlling extrusion process parameters. In this study, some possibilities for the application of broken rice and purslane in extrusion processing were proposed.

Thermal error prediction of ball screw feed system based on inverse heat transfer analysis

The thermal error of the ball screw feed system will reduce the positioning accuracy of the machine tool, and the main reason for the thermal error is the friction heat generated by bearings and screw nut in the feed system. Therefore, a time-varying thermal error prediction method of the ball screw feed system based on the inverse method is proposed in this paper. Based on data-driven and dynamic thermal network model, the heat source estimation method of ball screw feed system under unsteady thermal effect is established, and the thermodynamic equilibrium equation is deduced into explicit form for heat source load identification. Aiming at the common matrix ill-conditioned problem of load identification, the regularization algorithm is used to identify the heat source load, and the optimal selection method of regularization parameters is proposed based on Monte Carlo algorithm. Using the collected temperature experiment data and the position data of the moving nut, the dynamic heat source load, temperature field, and thermal error of the feed system under the actual working condition are predicted and analyzed by using the inverse method. Finally, the accuracy and effectiveness of the prediction method are verified by experiment. The inverse method proposed in this paper has great application potential for the prediction and estimation of heat source and temperature field of machine tools and various mechanical structures.

Effects of different extrusion temperatures on physicochemical, rheological and digestion properties of rice flour produced in a pilot‐scale extruder

SummaryThis research was to study the effects of different die temperatures (125, 135, 145, 155, 165 °C) on the physicochemical, rheological, structural properties and in vitro digestion characteristics of extruded rice flour. In this work, the moisture content of feed rice flour was controlled at 18% (w/w, on a dry basis). A twin‐screw with 65 mm diameter was used. Feed rate and screw speed were set at 120 kg h−1 and 120 rad min−1 respectively to control variables. The results indicated that the water solubility index improved but the water absorption index reduced at a higher temperature. The total starch content reduced as the temperature increased, but the amylose content was insusceptible to the temperature. Average particle size significantly decreased after extrusion due to the damage of starch granules. The water dispersion system of the extruded rice flour possessed more liquid characteristics than that of raw rice flour. Steady shear analysis revealed that the flow was in a shear thinning behaviour, and apparent viscosity was improved by extrusion but negatively related to extrusion temperature. Crystal type of starch turned from A to V after extrusion. The interaction among rice flour components was mainly non‐covalent and could be enhanced by extrusion. The ratio of 1047/1022 cm−1 reflected that the ordered structure was destroyed by extrusion, which was further confirmed by the differential scanning calorimeter result. In addition, the digestibility of extruded rice flour was improved. The in vitro digestibility of protein increased from 75.77% to 86.44% and resistant starch content significantly decreased as extrusion temperature increased.

Detecting preload degradation of a ball screw feed system using high-frequency reconstruction and support vector machine

Ball screws need to be applied with different preloads in most applications, however, very few studies had paid attention to preload detection, which is one of the most common failure modes of ball screws. To detect the preload of a ball screw, we propose a novel approach using vibration signals and ensemble empirical mode decomposition (EEMD) combined with linear discriminant analysis (LDA) and a support vector machine (SVM). The vibration signals under different preloads are obtained for the same ball screw through degradation experiments, and decomposed and reconstructed by EEMD. Statistical features are extracted from the reconstructed signals in the time and frequency domains. Linear discriminant analysis is used to reduce the dimensionality of the original feature space. Finally, the preload can be identified by the SVM, in which the identification accuracy can be higher than 90%. Further analysis showed that the high-frequency signal has a stronger correlation with preload degradation than the low-frequency signal, and the proposed method can be more effective than other existing methods, especially when the degradation of preload is more than 300N.

Development of a Novel Rice-Based Snack Enriched with Chicory Root: Physicochemical and Sensory Properties.

A novel rice-based snack enriched with chicory root flour (CRF) was developed by twin-screw extrusion. Chicory (Cichorium intybus L.) is one of the promising medicinal plants for the development of innovative food and may be considered a functional food ingredient. Central composite design (CCD) was employed to generate snack formulations by varying feed moisture (M, 16.3–22.5%), screw speed (SS, 500–900 rpm) and CRF content (20–40%). The optimization according to artificial neural network modeling and a genetic algorithm was applied to define optimal process conditions (17.6% moisture, 820 rpm and 24.1% of CRF) for obtaining the product with the highest expansion (3.34), crispiness (3.22 × 10−3), volume (2040 m3), degree of gelatinization (69.70%) and good color properties. Bulk density (110.33 g/L), density (250 kg/m3), and hardness (98.74 N) resulted in low values for the optimal sample. The descriptive sensory analysis evaluated low hardness and bitterness, with high crispiness for the optimal extrudate. This study points to the possibility of a novel chicory enriched extrudate production with desirable physicochemical and sensory properties.

Analysis of static electricity generation and elimination in the process of food powder screw feeding

AbstractThe static electricity in the powder can easily cause poor packaging accuracy, incomplete heat‐sealing of the packaging bag and certain safety hazards. Therefore, the electrostatic generation and elimination of wheat flour and wheat starch were studied in the process of powder screw feeding. Firstly, taking powder particle size, screw speed and conveying distance as influencing factors, the law of static electricity generation in the process of powder screw conveying is studied. Then, an adjustable DC power supply and an ion fan were used to apply voltage and ion wind during the powder screw feeding process to study the elimination of powder static electricity. The research results show that the electrostatic charge of wheat flour and wheat starch is positive. The greater the screw speed, the more severe the powder collision and friction, and the greater the increase in powder charge‐to‐mass ratio. The larger the conveying distance, the greater the increase in the powder‐to‐mass ratio, and when the conveying distance reaches 5200 mm, the experimental powder‐to‐mass ratio tends to be stable. The gain and loss of the charge of wheat starch with small particle size is obviously greater than that of wheat flour with large particle size. The ability and stability of adding ion wind at the outlet of the screw feeder to eliminate static electricity are obviously stronger than the ability and stability of adding voltage to eliminate static electricity.Practical applicationsThe static electricity generated in the process of screw conveying and feeding causes trouble to the packaging weighing, packaging sealing and safety production of powder. Therefore, this paper studies the electric characteristics of food powder in the process of screw transportation and the influence of various factors on the electrostatic generation law, and also through experiments to compare the two methods of electrostatic elimination. This study provides ideas and references for reducing the generation and elimination of static electricity in the process of screw transportation of food powder, so as to improve the packaging accuracy, packaging quality and reduce safety risks in actual industrial production.

Frictional contacts between individual woody biomass particles under wet and dry conditions

Friction between wood particles can be a critical property when designing processing equipment for creating cellulosic biofuels and similar natural products. Also, as wood processing is likely to occur year-round, understanding the friction between wet as well as dry wood particles can help design and model equipment, such as screw feeders. Here, a tribo-rheometry method was developed using a commercial rheometer that measured the torque required to rotate two contacting millimeter-scale wood chip particles. First, a range of normal forces were used to find the limits of the experimental method. Torque values were measured for seven pairs of wood chip particles at 1 N normal force under both dry and wet conditions, at both ambient conditions and in a humidity-controlled chamber. The torque required to rotate the wet particles was consistently higher than that of the dry particles, although differences were not quite statistically significant when measurements were performed at ambient conditions. Using humidity control resulted in torque values for wet particles of 1900 μNm and 900 μNm for dry particles. Finally, the friction coefficient was calculated as 0.23 for wet particles and 0.11 for dry particles when humidity was controlled. These frictions coefficients agreed with values for wood reported in the literature. Overall, controlling humidity is strongly recommended to quantify the range of friction for particles that uptake water, including granular systems from biomass to food to powders. Friction higher for wet vs dry wood particles at constant humidity from bar graph on left. On right parallel plate rheomter shown with two wood particles between the plates and axial force pushing plates/particles together and shear force rotating bottom plate. • Tribo-rheometric method developed for controlled moisture friction experiments. • Individual particle friction measured for millimeter-scale wood particles. • Friction coefficients higher for wet versus dry wood particles.

OPTIMIZATION OF THE WORKING SPEED OF THE AUGER SNOWPLOW

The article deals with the problem of determining the optimal working speed of the auger snowplow when the auger feeder interacts with snow based on the method of analyzing the fourth coordinate. The mathematical model of the fourth coordinate of the working process is determined by the ratio of the mathematical model of the work of resistance forces during the operation to the mathematical model of the power expended on the performance of the corresponding operation. The efficient operation of the screw feeder depends on the combination of two operations performed by the working body: cutting snow and moving snow to the rotor.

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

One dominant challenge facing the development of biorefineries is achieving consistent system throughput with highly variant biomass feedstock quality and handling performance. Current handling unit operations are adapted from other sectors (primarily agriculture), where some simplifying assumptions about granular mechanics and flow performance do not translate well to a highly compressible and anisotropic material with nonlinear time- and stress-dependent properties. This work explores the shear and frictional properties of loblolly pine at multiple experimental test apparatus and particle scales to elucidate a property window that defines the shear behavior over a range of material attributes (particle size, size distribution, moisture content, etc.). In general, it was observed that the bulk internal friction and apparent cohesion depend strongly on both the stress state of the sample in granular shear testers and the overall particle size and distribution span. For equipment designed to characterize the quasi-static shear stress failure of bulk materials ranging from 50 to 1,000 ml in test volume, similar test results were observed for finely milled particles (50% passing size of 1.4 mm) with a narrow size distribution (span between 10 and 90% passing size of 0.9 mm), while stress chaining and over-torque issues persisted for the bench-scale test apparatus for larger particle sizes or widely dispersed sample sizes. Measurement of the anisotropic particle–particle friction ranged from coefficients of approximately 0.20 to 0.45 and resulted in significantly higher and more variable friction measurements for larger particle sizes and in perpendicular alignment orientations. To supplement these laboratory-scale properties, this work explores the flow of loblolly pine and Douglas fir through a pilot-scale wedge-shaped hopper and a screw feeder. For the gravity-driven hopper flow, the critical arching distance and mass discharge rate ranged from approximately 10 to 30 mm and 2 to 16 tons/hour, respectively, for both materials, where the arching distance depends strongly on the overall particle size and depends less on the hopper inclination angle. Comparatively, the auger feeder was found to be much more impacted by the size of the particles, where smaller particles had a more consistent and stable flow while consuming less power.

Surface Quality Control Strategy of Aspherical Mold Based on Screw Feed Polishing of Small Polishing Tool.

For small aspherical molds, it is difficult for the existing polishing method to take into account the correction of the surface error and the control of the uniformity of the surface roughness (SR) distribution, because the polishing tool is always larger than the small mold. Therefore, we used viscoelastic polyester fiber cloth to wrap the small steel ball as a polishing tool to adapt to the surface shape change of the aspherical mold, and designed a semi-flexible small polishing disc tool with microstructure, which can better adapt to the curvature change of aspherical surface and obtain better SR Ra. At the same time, a combined polishing method of constant speed and variable speed for screw feed was proposed to improve the uniformity of SR distribution in the paper. Then, a series of theoretical analysis and experimental verification were carried out in this paper to predict the tool influence function (TIF) of the two polishing tools and the effectiveness of the combined polishing method. In the experiment, a TIF bandwidth of about 0.46 mm was obtained with a small spherical polishing tool, which favors the surface shape correction of the small aspherical mold. The experiment of uniform removal with a small polishing disc tool was carried out to quickly reduce the Ra. Finally, the surface quality of the aspherical mold was effectively improved, combined with the constant speed and variable speed polishing modes of screw feed of the small spherical polishing tool and the smoothing effect of the small polishing disc tool. The peak valley (PV) of two small aspherical molds with an optical effective diameter less than 13 mm converged from 0.3572 μm and 0.2075 μm to 0.1282 μm and 0.071 μm, respectively. At the same time, the SR dispersion coefficient was reduced from 27.9% and 41.6% to 14.2% and 12.7%, respectively. The study provides a good solution for the surface quality control of small aspherical molds.

Optimizing the extrusion conditions for the production of expanded intermediate wheatgrass (Thinopyrum intermedium) products

In this study, the effects of extrusion conditions such as feed moisture content (20%, 24%, and 28%), screw speed (200, 300, and 400 rpm), and extrusion temperature (130, 150, and 170°C) on the physical and functional properties (moisture content, expansion ratio, bulk density, hardness, water absorption index [WAI], water solubility index [WSI]) of intermediate wheatgrass (IWG) were investigated for the first time. Response surface methodology was used to model and optimize the extrusion conditions to produce expanded IWG. The model coefficient of determination (R 2) was high for all the responses (0.87–0.98). All the models were found to be significant (p < 0.05) and were validated with independent experiments. Generally, all the extrusion conditions were found to have significant effects on the IWG properties measured. Increasing the screw speed and decreasing the extrusion temperature resulted in IWG extrudates with a high expansion ratio. This also resulted in IWG extrudates with generally low hardness and bulk density. Screw speed was found to have the most significant effect on the WAI and WSI, with increasing screw speed resulting in a significant (p < 0.05) decrease in WAI and a significant (p < 0.05) increase in WSI. The optimum conditions for obtaining an IWG extrudate with a high expansion ratio and WAI were found to be 20% feed moisture, 200 –356 rpm screw speed, and 130–154°C extrusion temperature.Practical ApplicationExtrusion cooking was employed in the production of expanded IWG. This research could provide a foundation to produce expanded IWG, which can potentially be used as breakfast cereals and snacks. This is critical in the efforts to commercialize IWG for mainstream food applications.

Dynamic modeling and analysis on lateral vibration of ball screw feed system

Dynamic modeling and analysis on lateral vibration of ball screw feed system