Numerical investigation of screw design influence on screw feeding in a roller compactor

Roller compaction refers to a dry granulation process where fine particulate feed is fed to the counter rotating rolls of a roller compactor to form ribbons which are further milled to produce free flowing agglomerates. For the continuous production of ribbons, there needs to be an adequate supply of powder by the screw to the rolls without any interruptions. In general, screws used in roller compactors are designed to convey powders of all types (cohesive, bulky, compressible, etc.), whereby usage of different screw designs for different powder types may be avoided. However, using such single screw type roller compactors for poor flowing powders may be challenging. On the other hand, the selection of the right screw for a given powder can only be done based on a combination of prior experience and trial-and-error experimentation. Empirical correlations exist to predict the draw down rate of screw feeders depending on their design, however, these correlations assume that there is continuous supply of powder by the screw, which limits its application to free-flowing powders only. To address this, in this study numerical simulations are performed based on discrete element method (DEM) to investigate the impact of screw design on the powder supply to rolls for cohesive and poorly flowing powders. The geometry considered includes a hopper, horizontal feeding screw below the hopper, and two counter-rotating rolls at the end of the screw. Two different screw designs are investigated where the main difference between them is the pitch length. The influence of scraper speed is investigated. Additionally, the influence of material attribute such as cohesion is studied. For both designs, the simulation results calculated include the rate of powder supply by the screw, velocity of particles in the screw etc. The simulation results of powder supply rate are also compared with results obtained based on empirical correlation. Overall, this simulation approach helps in selecting appropriate screw design for the given cohesive powder

Integrated Pest Management (IPM) for Reducing Pesticide Residues in Crops and Natural Resources

Investigation on the pesticide residues during 2006–2009 in various crops and natural resources (soil and water) in the study village (Kothapally, Telangana State (TS)) indicated the presence of a wide range of insecticidal residues. Pooled data of the 80 food crop and cotton samples, two rice grain samples (3 %) showed beta endosulfan residues, and two (3 %) soil samples showed alpha and beta endosulfan residues. In vegetables of the 75 tomato samples, 26 (35 %) were found contaminated with residues of which 4 % had residues above MRLs. Among the 80 brinjal samples, 46 (56 %) had residues, of these 4 % samples had residues above MRLs. Only 13 soil samples from vegetable fields were found contaminated. The frequency of contamination in brinjal fields was high and none of the pulses and cotton samples revealed any pesticide contamination. IPM fields showed substantial reduction sprays which in-turn reflected in lower residues. Initial studies on water analysis indicated the presence of residues in all water sources with higher in bore wells compared to open wells, however, by 2009 the water bodies reflected no residues above the detectable level

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Not AvailableBy the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed. View Full-Text Keywords: macronutrients; mechanisms; micronutrients; beneficial nutrients; abiotic stress ▼ Show Figures Figure 1 This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Not Availabl