جستجوی مقالات مرتبط با کلیدواژه "pellet" در نشریات گروه "مکانیزاسیون کشاورزی"

Agricultural residues and wastes are the main source of biomass for use in bioenergy production and animal and poultry feed production industries. These biomasses in their original form have a large volume and low energy (per unit volume) and require a lot of space and extensive movement. Therefore, one of the methods of optimal use of these biomasses is to transform them into pellets, which have more mass and energy per unit volume and enable their easier use and transportation. Currently, biomass has the fourth place in energy supply after oil, natural gas and coal and provides approximately 14% of the world's energy needs. The use of biomass, especially in European Union countries, as an attractive source for replacing fossil fuels is developing and expanding. The use of biomass as fuel has significantly reduced the amount of environmental pollutants, so that the amount of CO2 absorbed from the atmosphere during biomass growth is similar to the amount produced during combustion, followed by a net cycle of production.

 The raw materials for making pellets were prepared from spruce wood sawdust (collected from a sawmill in Sari) as well as corn stalk and soybean residues in the fields of Dasht Naz in Sari. The desired materials were transferred to the laboratory in the necessary amount and kept at ambient temperature until the experiments. The samples were first crushed into 20 mm sizes and then powdered using a grain mill (Mehr Tehiz company, Iran) and passed through 18 mesh sieves in the range of 1 mm to make pellets. A palletization mechanism was used to compress the pellet. This system was designed and built in biosystem mechanics of Sari University of Agricultural Sciences and Natural Resources. The material was placed inside a steel mold with a cylinder inner diameter of 8.05 mm and a height of 150 mm with a blocked end. A piston with a diameter of 8 mm connected to the driving arm of the tension-compression test machine was used to compress the material. Loading by a piston with a quasi-static speed of 5 mm per minute is compressed to a pressure of 1300 N.

In this research, the mechanical and thermal properties of pellets made from the combination of spruce sawdust and corn and soybean residues were evaluated. In the present study, the effect of four combinations of agricultural and forest materials at two moisture levels (12% and 18% based on fresh weight) on the indices of density, compressibility, Hausner ratio, strength and calorific value of the produced pellets were investigated and evaluated. it placed. The results showed that the pellet density at 18% humidity was lower than the density at 12% humidity. The highest density related to the combination of 60% spruce wood sawdust-40% corn stalks was obtained with a value of about 149 kg/m3 and the lowest value related to 100% soybean stalks was about 110 kg/m3. Also, the ratio of Hanser and CI in the combined pellets that have a higher percentage of sawdust and also in the combination of sawdust with corn stalks are within the permissible range. The highest pellet strength was 23.8 N/cm corresponding to 100% sawdust at 18% humidity and the lowest was 15.4 N/cm corresponding to 100% soybean stalk at 12% humidity. The calorific value of the pellets is in the range of 14.37 to 18.52 MJ/kg, which is the minimum value for the pellet made from 100% soybean stalk at 18% humidity and the maximum value for the pellet made from 100% fir wood sawdust and It was obtained at a humidity of 12%. Therefore, the use of agricultural wastes and their proper combination is a good option for the production of biofuels due to their density and strength.

 The type of biological waste and moisture percentage affect the physical and mechanical properties of the produced pellets. In general, the combination of spruce wood sawdust with corn stalks and soybean improved the mechanical and thermal properties of the pellet. Hanser's ratio and compressibility in the combined pellets that have a higher percentage of sawdust and also in the combination of sawdust with corn stalks are within the standard range. Also, in the compositions that have a higher proportion of spruce wood sawdust and lower moisture, the density and strength factors of the pellet increase. The highest and lowest calorific values were obtained in a higher ratio of sawdust and a higher ratio of corn, respectively. Therefore, it is possible to make pellets from the waste of garden and agricultural products that have good density and strength and high calorific value.

One of the best ways to use biomass is to convert them into a pellet that has more mass and energy per unit volume and makes it easier to use and transport. Various factors are involved in the process of pelletizing, which helps to optimize the process. In this study, the effect of temperature, compression force and mixing ratio were investigated on the mechanical properties of pellets made from rice bran and sugar cane molasses. The results showed that, except compression force and the interaction between the compression force and the temperature, other variables and their interactions have significant effect (p < 0.01) on the dependent variables. Mean comparison showed that increasing the amount of molasses in combination increased the compressive strength of the pellet in axial and radial direction. The highest compression strength was obtained at the ratio of 1 to 1.50 (rice bran to molasses) and 1300N compression force. The maximum bending strength of pellets was significant in all three ratios, and increasing sugar cane molasses increased the bending strength. Increasing the mold temperature and compression force increased the strength of the pellets in both axial and radial directions as well as their bending strength. Maximum density and drop resistance of pellet in the ratio of 1 to 1.65 (rice bran to molasses), compression force of 1300 N and temperature of 70 ° C were 1213 kg/m3 and 93.5%, respectively. Generally, in the pelletizing process the mixing ratio, compression force and temperature have an effect on the strength of the pellet.

One of the methods of using livestock exhaust is compressing and pelletting it, which causes facilitation of transportation, reduction of odor and gradual release of nitrogen. For manure pelleting, extruder and disk pelleting are used. Since the stones existing materials in the stored manure cause damage to the pelletting apparatus, so the removal of the stone from the manure before the processing is necessary. In this research, with the aim of separation the rock from the manure, a gravity separator was designed and fabricated. The performance of the device was evaluated by changing the three slope parameters of the material separator plates, manure moisture content and the size of the stone and manure dimensions The changed level was for 10, 15 and 20 ° slopes of separators, 10, 30 and 50% of the moisture content of manure, and for the particle size of less than 10, 10 to 20 and 20 to 50 mm. The maximum device separation efficiency of the stone from the manure was 76.81% at 10 ° slope, 50% moisture content and a particle size less than 10 mm.

Composting livestock manure and municipal solid waste is an appropriate method for waste management in order to stabilize organic wastes. The low specific mass of compost causes problems in transportion and storage activities and increases the costs. In this study some parameters affecting the pellets production was investigated. Parameters considered were: particle size (1 and 2 millimeter), pellet moisture content (25, 35 and 45 percent) and kneading length (1, 2 and 3 meter). Results showed that the specific density of pellets produced under both levels of particle size, increased with increasing the Length of kneading at all levels. Interaction effect of moisture content and kneading length on the rate of fractured pellets showed that, the maximum amount of force was (556.32N) which belonged to treatment with (moisture content of 35% and length of kneading of 3 m). Also the interaction effect of particle density and length of kneading showed that maximum toughness value was (1.03 MJ/m3) which belonged to particle density of 1mm and kneading length 3 m.

Converting the organic wastes and losses into compost is an appropriate technique to stabilize organic materials. One of the limitative factors in transporting and storing the composts is their low specific mass which usually leads to increase costs in their processing. To overcome this limitation, several methods such as pelleting have been proposed especially for efficient processing of powdery materials. In this study, the effects of pellet particle size (in two levels: 1 and 2 mm), pellet’s moisture content (in three levels: 25, 35, and 45%, wet basis), and kneading length (in three levels: 1, 2, and 3 m) have been investigated on some mechanical properties of obtained pellets including fracture energy, fracture force, and toughness. Obtained pellets were produced using a kneading extruder machine. Experimental results showed that the effect of length of kneading on all studied mechanical properties was significant (p

Densification of biomass material that usually has a low density is proper way to increasing density، reduce transportation cost and simplify storage and distribution of these materials. Pellet production using extrusion process is a common method for densification. The goal of this research is optimization of specific energy consumption for extrusion process considering its effect on pellet density. Compost was extruded into cylindrical pellets utilizing open-end dies under axial stress from a vertical piston applied by a hydraulic press. The effects of independent variables، including the raw material moisture content (35، 40 and 45% (w. b.))، particles size (0. 3، 0. 9 and 1. 5 mm)، speed of piston (2، 6 and10 mm/s)، and die length (8، 10 and 12 mm) on specific energy consumption and pellet density، were determined. The experiments were designed using response surface methodology based on Box Behnken design (BBD) in order to optimize. The results revealed that all independent variables have significant effects on studied responses in this research at P<0. 01. The optimum values of the factors for high density and low specific energy consumption were: moisture content between 40-45%، speed of 2 mm/s، particle size from 0. 8 to 1 mm and die lengths of 10 to 12 mm.

Agglomeration followed by pelleting is an efficient method to decrease transport costs and increase economic efficiency of composting municipal waste. The moisture content of compost is the most important parameter of the pellet making process for any type of manufacturing device. The experiments in this study were done at moisture contents of 35%, 45% and 50% at extruder shaft rotational speeds of 100, 150, 200 and 250 rpm. The materials were first processed using a mixer and kneading device then made into pellets using a single screw extruder. The durability of the pellets at different moisture contents were tested to determine the optimum moisture content and its effect on the properties of the pellets. The results showed that moisture content of the compost, rotational speed of extruder screw and the interaction of these parameters significantly affected the durability of the pellets. Durability increased from 35.86% to 78.29% as moisture content increased from 35% to 45% (w.b.). Durability was increased significantly at all rotational speeds as moisture content increased from 35% to 45% (w.b.). Increasing the moisture content produced no significant effect for the strength of the pellets at a rotational speed of 150 rpm. The strength was higher at 35% moisture content than for 45% moisture content.

A field study was conducted at Aboureihan research field of Tehran University in 2009 to find out the effect of nitrogen pellet fertilizer on the grain yield and nitrogen use efficiency of corn (Single Cross 704). The factorial design of the study comprised of randomized complete block with three replications. Factors of this experiment including: first factor was two levels of fertilizer application method (pellet and mixed with soil) and second factor was four levels of nitrogen fertilizer pulse manure (46+600، 92+600، 138+600 and 184+600 kg/ha). In this research، a screw extruder setup was designed and manufactured. Increasing N fertilizer from 46 to 184 kg/ha had significant effect on all yield and yield components traits except number of seed rows per ear. Maximum grain yield was obtained with pellet and 184 N kg/ha treatment. Statistical analysis indicated that NUE، as well as agronomic efficiency (AE) were reduced while physiological efficiency (PE) increased with increasing N (pellet) rates.