Screen Hole Diameter Research Articles

Corn physical characteristics on piglet performance

This study aimed to correlate the physical characteristics of ground corn, at different crushing intensities, with the zootechnical performance of piglets in the nursery phase. Forty piglets (20 castrated males and 20 females) with an initial average weight of 15.7±1.98 kg and final weight of 32.5±3.27 kg were used. They were subjected to the same type of experimental diet (4% of commercial premix for the phase, 29% of soybean meal, and 67% of ground corn), with the only difference being the corn grinding process. The corn used was fractionated into five portions, and each one of them was crushed in a hammermill equipped with a different screen hole diameter (2; 2.5; 3; 3.5 and 4 mm). Which resulted in ground corn with the following particle sizes (PS): 518, 580, 628, 706 and 740 μm, and the following corn geometric standard deviations (GSD): 1.72, 1.71, 1.75, 1.80 and 1.90, respectively. The piglets were distributed in a completely randomized design with five treatments and four replications, with the experimental units being formed by pens with two piglets each. There was no effect (p > 0.10) from grinding intensities on daily feed intake (DFI) and daily weight gain (DWG). Conversely, there was an effect (p < 0.10) from different grinding intensities on feed conversion (FC). The PS and GSD of both the corn and diet, as well as the corn fractions retained on the 4-, 2- and 1.2-mm test sieves showed positive correlations with FC (p < 0.05). On the other hand, the corn fractions retained on the 0.6-, 0.3- and 0.15-mm teste sieves showed negative correlations with FC (p < 0.05). The linear model was the one that fitted the estimated data into the data observed for FC. A corn PS reduction from 740 to 580 μm promoted a linear improvement in FC. The use of corn fractions, retained on the 1-, 2- and 0.3-mm test sieves, and the use of corn GSD and diet GSD as independent variables showed a higher R² than that obtained with the use of corn PS as an independent variable in linear equations for estimating FC.

Evaluation of fines separation from unbleached softwood kraft pulp using microperforated hole screens

AbstractThe application of a bench scale and an industrial scale pressure screen to separate cellulosic fines from an unbleached softwood kraft pulp containing 5 % (w/w) primary fines was investigated and the results were compared. In the bench scale trials different microperforated screens with hole diameters of 150 µm, 250 µm, 400 µm and 600 µm were used. Based on these results a screen hole diameter of 400 µm was selected for the industrial scale trials. In all cases, a high accept flow rate proved to be the crucial parameter for high removal efficiency of the fines material and a removal efficiency of well above 50 % could be achieved. Further of interest were the limiting factors regarding increased accept flow rates with a focus on the interrelations between pressure difference, slot velocity and reject consistency. As expected, investigation of electric energy demand showed a correlation between removal efficiency and specific energy consumption, which did not exceed 35 kWh/t(od) feed.

Evaluation of Hammermill Tip Speed, Air Assist, and Screen Hole Diameter on Ground Corn Characteristics

This study was performed to evaluate hammermill tip speed, assistive airflow, and screen hole diameter on hammermill throughput and characteristics of ground corn. Corn was ground using two Andritz hammermills measuring 1 m in diameter each equipped with 72 hammers and 300 HP motors. Treatments were arranged in a 3 × 3 × 3 factorial design with three tip speeds (3774, 4975, and 6176 m/min), three screen hole diameters (2.3, 3.9, and 6.3 mm), and three air flow rates (1062, 1416, and 1770 fan revolutions per minute). Corn was ground on three separate days to create three replications and treatments were randomized within day. Samples were collected and analyzed for moisture, particle size, and flowability characteristics. There was a 3-way interaction (p = 0.029) for standard deviation (Sgw). There was a screen hole diameter × hammer tip speed interaction (p < 0.001) for geometric mean particle size dgw (p < 0.001) and composite flow index (CFI) (p < 0.001). When tip speed increased from 3774 to 6176 m/min, the rate of decrease in dgw was greater as screen hole diameter increased from 2.3 to 6.3 mm. For CFI, increasing tip speed decreased the CFI of ground corn when ground using the 3.9 and 6.3 mm screen. However, when grinding corn using the 2.3 mm screen, there was no evidence of difference in CFI when increasing tip speed. In conclusion, the air flow rate did not influence dgw of corn, but hammer tip speed and screen size were altered and achieved a range of dgw from 304 to 617 µm.

149 Evaluation of Hammermill Tip Speed, Air Assist, and Screen Hole Diameter on Ground Corn Characteristics

Abstract This study was performed to evaluate hammermill tip speed, assistive airflow and screen hole diameter on hammermill throughput and characteristics of ground corn. Corn was ground using two Andritz hammermills (Model: 4330–6, Andritz Feed & Biofuel, Muncy,PA) measuring 1-m in diameter each equipped with 72 hammers and 300 HP motors. Treatments were arranged in a 3 × 3 × 3 factorial design with 3 tip speeds (3,774, 4,975, and 6,176 m/min), 3 screen hole diameters (2.3, 3.9 and 6.3 mm), and 3 air flow rates (1,062, 1,416, and 1,770 fan RPM). Corn was ground on 3 separate days to create 3 replications and treatments were randomized within day. Samples were collected and analyzed for moisture, particle size, and flowability characteristics. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with grinding run serving as the experimental unit and day serving as the block. There was a 3-way interaction for standard deviation (Sgw), (linear screen hole diameter × linear hammer tip speed × linear air flow, P = 0.029). There was a screen hole diameter × hammer tip speed interaction (P < 0.001) for geometric mean particle size dgw (P < 0.001) and composite flow index (CFI) (P < 0.001). When tip speed increased from 3,774 to 6,176 m/min the rate of decrease in dgw was greater as screen hole diameter increased from 2.3 to 6.3 mm resulting in a 67, 111, and 254 µm decrease in dgw for corn ground using the 2.3, 3.9, and 6.3 mm screen hole diameter, respectively. For CFI, increasing tip speed decreased the CFI of ground corn when ground using the 3.9 and 6.3 mm screen. However, when grinding corn using the 2.3 mm screen, there was no evidence of difference in CFI when increasing tip speed. In conclusion, the air flow rate did not influence dgw of corn but hammer tip speed and screen size were altered and achieved a range of dgw from 304 to 617 µm.

Evaluation of Impact Hammer Mill for Limestone Crushing for Acidic Soil

Soil acidity becomes a serious threat to crop production in most highlands of Ethiopia particularly in Western parts of Oromia. Frequent tillage, removal of crop residues and mono-cropping and heavy rainfall contributes to soil acidification by leaching of cations. Agricultural limestone raises soil pH and reduces solubility of potentially toxic elements such as hydrogen, aluminum (Al3+) and manganese (Mn) at optimum nutrient uptake by crops. To elucidate problems associated with soil acidity, a motorized agricultural limestone crusher was fabricated and evaluated. Performance of the prototype hammer mill machine, in terms of crushing capacity (kg/h), crushing efficiency (%), mean particle size (mm), fuel consumption (ml/kg) or energy consumption (wh/kg) was evaluated. Tests were carried out at engine speeds of 540, 720, 900 rpm, screen hole diameter of 2, 4, 6 mm and feed rates of 3.50, 7.00, 10.50 kg/min. The highest crushing capacity 630.32 kg/hr was recorded at 900 rpm engine speed, 6mm screen hole diameter and at 10.50 kg/min feed rate whereas the minimum 65.62 kg/h was observed at 540 rpm hammer mill speed, 2 mm screen hole diameter and at 3.50 kg/min feed rate. The mean consumed energy ranged from 15.47 to 149.16 Wh/kg with hammer rotor speed of 540 to 900 rpm, screen hole diameter of 2 to 6 mm and the feeding rate of 3.5 to 10.5 kg/min. The mean particle size ranged from 0.121 to 0.448 mm with hammer rotor speed of 540 to 900 rpm, screen holes diameter of 2 to 6 mm and the feeding rate of 3.5 to 10.5 kg/min. It could be noticed that the lowest values of mean particle size were obtained at engine speed of 900 rpm, screen hole diameter of 2 mm and feed rate of 10.5 kg/min.

Evaluating Hammermill Tip Speed, Air Assist, and Screen Hole Diameter on Ground Corn Characteristics

Evaluating Hammermill Tip Speed, Air Assist, and Screen Hole Diameter on Ground Corn Characteristics

The Effect of Screen Hole Diameter and Hammer Tip Speed on the Subsequent Particle Size of Ground Corn Analyzed With and Without Sieving Agent

The Effect of Screen Hole Diameter and Hammer Tip Speed on the Subsequent Particle Size of Ground Corn Analyzed With and Without Sieving Agent

319 The Effect of Hammermill Screen Hole Diameter and Hammer Tip Speed on Particle Size and Flow Ability of Ground Corn.

319 The Effect of Hammermill Screen Hole Diameter and Hammer Tip Speed on Particle Size and Flow Ability of Ground Corn.

DEVELOPING MINCER HOUSEHOLD FOR OPTIMIZATION OF LEEK AIHAM PORRUM

This research was carried out in Faculty of Agricultural Engineering, Al- Azhar university, Nasr city during 2016 season to leek cultivated after cutting leaves for slices (length slice 3 cm). The aim of green leek chop is to utilization of producing juicing which is considered as the most effective preparation for securing all health benefits of leek. To achieve this aim, a house mincer household with a (1.5 hp) motor was used. Factors studied were two type sample ( head and lateral ), two moisture content headed ( 69 and 85 % ), lateral (68 and 80 %) and screen hole diameters ( 4, 5 and 6 mm ) at rotation speed (400 , 500 and 600 rpm ) with feeding mass 250 g. The performance of the chop was evaluated according to the chop. Productivity, energy requirements and sample content from protein and Fat. The results showed that the highest productivity was 11.54 kg / h lateral chop and highest productivity was 15.00 kg / h head chop and minimum specific energy 0.01 kw. h / kg lateral chop and minimum specific energy 0.08 kw . h / kg head obtained at 600 rpm and screen hole diameters 7 mm, 80 % moisture content for lateral sample and 85% moisture content for head sample while the requirement power highest 0.252 kw at 3 mm screen hole diameter, 80 % moisture content for lateral sample and 0.17 kw at 5 mm screen hole diameter, 68 % moisture content for lateral sample at rotation speed of 400 rpm, and the analysis of sample protein and fat contents of with lateral and head are (11.96 and 12.14 %) and( 2.55 and 2.57 %) respectively.

The Effect of Hammermill Screen Hole Diameter and Hammer Tip Speed on Particle Size and Flowability of Ground Corn

The Effect of Hammermill Screen Hole Diameter and Hammer Tip Speed on Particle Size and Flowability of Ground Corn

PERFORMANCE EVALUATION OF TWO DIFFERENT HAMMER MILLS FOR GRINDING CORN COBS

The grinding operations of corn cobs using two different local manufactured hammer mills namely: Aamagro (mill A), and El-Gohary (mill E) were evaluated and compared to be used as an ingredient in feedstuffs for animal and poultry farms. The field experiments were carried out at Sakha Agricultural Research Station, Kafrelsheikh Governorate, Egypt during the year of 2015. These experiments were deduced to evaluate and compare the performance of the investigated hammer mills under the effects of three feeding rate levels (0.2, 0.4 and 0.6ton/h), four rotor speed levels (1200, 1500, 1800 and 2100rpm), and two screen hole diameter levels (9 and 14mm) using corn cobs. The performances of both machines were evaluated in terms of: fineness degree (particle size distribution), machine productivity, power requirements, specific energy consumption, and machinery unit cost. The results revealed that, the optimum operating conditions for both A and E mills were obtained at rotor speed of 2100rpm, cobs feed rate of 0.2 ton/h and 9mm screen hole diameter. Whereas, under these conditions the maximum percentages of fine milled cobs (1.7-≤1.18mm) of were 63.71 and 53.16% for A and E mills, respectively. Also, mill productivity of 0.185 and 0.146ton/h, power requirements of 2.245 and 3.076kW and specific energy consumption of 12.134 and 21.065kW.h/ton were determined under the optimal operating conditions for A and E mills, respectively. Moreover, the estimated machinery unit cost for mill E was about 1.124 times that of mill A.

Particle segregation in a screen baffle packed fluidized bed

The segregation of binary particle mixtures was investigated in a horizontal screen baffle packed fluidized bed, which was operated continuously. In this study, the effects of the gas velocity, baffle spacing, screen size, feeding location, feeding rate, and bed height on particle segregation were examined. The results showed that the efficiency of particle segregation increases as the gas velocity, baffle spacing, and screen hole diameter decrease.

Extrusion-Spheronization of Blends of Carbopol 934 and Microcrystalline Cellulose

We evaluated the effects of several process variables on the pharmaceutical and drug release properties of extrusion-spheronization pellets of blends of Carbopol 934 and microcrystalline cellulose (MCC) containing a high proportion of Carbopol. The model drug was theophylline. Rheological monitoring during mixing was by mixer torque rheometry. Carbopol:MCC blends wetted with a CaCl2 solution showed different rheological behavior compared to blends with a high proportion of MCC wetted with water only. In contrast to previous suggestions, the optimal wetting point for extrusion did not coincide with the point of peak torque, but occurred just beyond this point, at much lower torque. The influence of process variables on blend properties was investigated with a three-variable factorial design (Carbopol:MCC ratio, wetting liquid proportion, CaCl2 :Carbopol ratio), and the influence of process variables on pellet properties with a four-variable design (the variables listed plus extrusion screen hole diameter). Blend torque values were strongly influenced by CaCl2 proportion, while mean pellet diameter was influenced by Carbopol:MCC ratio. Mean pellet diameter also differed depending on whether the pellets contained theophylline. The observed among-formulation differences in theophylline release kinetics were largely explained by differences in pellet size and theophylline hydration state. Compaction of pellets to form tablets markedly modified the drug release profile, making it biphasic.

押出造粒法による打錠用か粒の調製と製錠

The objective of the present study is to verify that tablets, which are superior in physical properties, dissolution characteristics, and drug content uniformity, can be manufactured directly from granules prepared by an extrusion granulation process. First, granules were experimentally produced by extrusion, by changing the hole diameter and thickness of screen of granulator, the binder content, and the binder adding method. A fraction of the extruded granules were crushed and then sized. Tablets were manufactured from both extruded and crashed granules. As a result, it is possible to manufacture tablets which meet the targeted properties: tablet hardness ≥40N; disintegration time≥300s directly from the extruded granules without crushing and sizing. The tablets showed superior dissolution characteristic despite their high hardness. In addition, the drug content is uniform over the tablets even when the model drug content is extremely small (1wt%). The targeted physical properties can be obtained by adding 0.5wt% powder binder when the screen hole diameter (0.5mm) is smaller than the screen thickness (0.6mm), or by adding 1.5wt% powder binder when the screen hole diameter (0.5mm) is larger than the screen thickness (0.4mm).

Ion Beamlet Divergence Characteristics of Two-Grid Multiple-Hole Ion-Accelerator Systems

An experimental investigation was performed to determine the divergence characteristics (distortion factor, divergence angle, and divergence factor ) of ion beamlets that were commonly formed using multiple-hole, ionaccelerator systems of ion thrusters. An isolated ion beamlet was observed three dimensionally using arrayed Faraday probes, and its divergence characteristics were determined as a function of geometrical grid parameters and grid voltages. Because xenon was used as a propellant and the grid voltages were chosen being conscious of a recent ion-thruster technology trend, the results can be used for designing ion thrusters by simply translating geometrical grid parameters. The results did not contradict those in previous studies that used argon and one- or two-dimensional beam diagnostics. Nomenclature da = accelerator-hole diameter, mm ds = screen-hole diameter, mm dsp = beamlet-separator-hole diameter, mm Fd = distortion factor, s/ S fD = divergence factor Jb = beamlet current, A Ji = ith probe current, A L = axial distance between accelerator grid and probes, cm lcc = hole center-to-center distance, mm le = effective acceleration length, mm lg = screen-to-accelerator-grid separation, mm lsp = accelerator-grid-to-separator separation, mm NP/H = normalized perveance per hole, A/V 3/2 R = net-to-total voltage ratio, Vn/ Vt Ri = ith probe radial location measured from beamlet

Ion extraction capabilities of two-grid accelerator systems

An experimental investigation into the ion extraction capabilities of two-grid accelerator systems common to electrostatic ion thrusters is described. This work resulted in a large body of experimental data which facilitates the selection of the accelerator system geometries and operating parameters necessary to maximize the extracted ion current. Results suggest that the impingement-limited perveance is not dramatically affected by reductions in screen hole diameter to 0.5 mm. Impingement-limited performance is shown to depend most strongly on grid separation distance, accelerator hole diameter ratio, the discharge-to-total accelerating voltage ratio, and the net-to-total accelerating voltage ratio. Results obtained at small grid separation ratios suggest a new grid operating condition where high beam current per hole levels are achieved at a specified net accelerating voltage. It is shown that this operating condition is realized at an optimum ratio of net-to-total accelerating voltage ratio which is typically quite high. The apparatus developed for this study is also shown to be well suited measuring the electron backstreaming and electrical breakdown characteristics of two-grid accelerator systems.

Ion extraction from a plasma

An experimental investigation of the physical processes governing ion extraction from a plasma is presented. The screen hole plasma sheath of a multiaperture ion accelerator system is defined by equipotential plots for a variety of accelerator system geometries and operating conditions. A sheath thickness of at least 15 Debye lengths is shown to be typical. The electron density variation within the sheath satisfies a Maxwell-Boltzmann density distribution at an effective electron temperature dependent on the discharge plasma primary-to-Maxwellian electron density ratio. Plasma ion flow up to and through the sheath is predominately one dimensional and the ions enter the sheath with a modified Bohm velocity. Low values of the screen grid thickness to screen hole diameter ratio give good ion focusing and high extracted ion currents because of the effect of screen webbing on ion focusing.