• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • Tagged with
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Korečkový elevátor / Bucked elevator

Kunert, Tomáš January 2008 (has links)
The goal of this master’s thesis is design of belt bucket elevator for wheat transportation. The first part of this thesis is focused on drive’s design with slightly marked bond to surrounding facilitie and structure. The following part is focused on design solution of the head and bottom unit of bucket elevator and other constructive details like type of bucket pouring, belt tensioning, driving shaft mounting in head unit, connection of drum with shaft, the way of attaching buckets etc.
2

Projekt linky pro moření obilnin / Project of transport line for dressing corn

Klíma, Petr January 2009 (has links)
Subject of this work is a project of transport line for corn dressing. In the document component parts of the transport line are described. As the submitter asked, some existing devices were retained and supplied with missing parts. Some of the missing parts are bucket elevators which transport corn to the cleaner and dressing device. At the end of the transport line there is a frame for easing sack filling and a weighing device.
3

Quality changes, dust generation, and commingling during grain elevator handling

Boac, Josephine Mina January 1900 (has links)
Doctor of Philosophy / Department of Biological & Agricultural Engineering / Mark E. Casada / Ronaldo G. Maghirang / The United States grain handling infrastructure is facing major challenges to meet worldwide customer demands for wholesome, quality, and safe grains and oilseeds for food and feed. Several challenges are maintaining grain quality during handling; reducing dust emissions for safety and health issues; growing shift from commodity-based to specialty (trait-specific) markets; proliferation of genetically modified crops for food, feed, fuel, pharmaceutical, and industrial uses; and threats from biological and chemical attacks. This study was conducted to characterize the quality of grain and feed during bucket elevator handling to meet customer demand for high quality and safe products. Specific objectives were to (1) determine the effect of repeated handling on the quality of feed pellets and corn; (2) characterize the dust generated during corn and wheat handling; (3) develop and evaluate particle models for simulating the flow of grain during elevator handling; and (4) accurately simulate grain commingling in elevator boots with discrete element method (DEM). Experiments were conducted at the research elevator of the USDA-ARS Center for Grain and Animal Health Research (CGAHR) to determine the effect of repeated handling on the quality of corn-based feed pellets and corn. Repeated handling did not significantly influence the durability indices of feed pellets and corn. The feed pellets, however, had significantly greater breakage (3.83% per transfer) than the corn (0.382% per transfer). The mass of particulate matter < 125 μm was less for feed pellets than for corn. These corn-based feed pellets can be an alternative to corn in view of their handling characteristics. Another series of experiments was conducted in the same elevator to characterize the dust generated during corn and wheat handling. Dust samples were collected from the lower and upper ducts upstream of the cyclones in the elevator. Handling corn produced more than twice as much total dust than handling wheat (185 g/t vs. 64.6 g/t). Analysis of dust samples with a laser diffraction analyzer showed that the corn samples produced smaller dust particles, and a greater proportion of small particles, than the wheat samples. Published data on material and interaction properties of selected grains and oilseeds that are relevant to DEM modeling were reviewed. Using these material and interaction properties and soybeans as the test material, the DEM fundamentals were validated by modeling the flow of soybean during handling with a commercial software package (EDEM). Soybean kernels were simulated with single- and multi-sphere particle shapes. A single-sphere particle model best simulated soybean kernels in the bulk property tests. The best particle model had a particle coefficient of restitution of 0.6; particle static friction of 0.45 for soybean-soybean contact (0.30 for soybean-steel interaction); particle rolling friction of 0.05; normal particle size distribution with standard deviation factor of 0.4; and particle shear modulus of 1.04 MPa. The single-sphere particle model for soybeans was implemented in EDEM to simulate grain commingling in a pilot-scale bucket elevator boot using 3D and quasi-2D models. Pilot-scale boot experiments of soybean commingling were performed to validate these models. Commingling was initially simulated with a full 3D model. Of the four quasi-2D boot models with reduced control volumes (4d, 5d, 6d, and 7d; i.e., control volume widths from 4 to 7 times the mean particle diameter) considered, the quasi-2D (6d) model predictions best matched those of the initial 3D model. Introduction of realistic vibration motion during the onset of clear soybeans improved the prediction capability of the quasi-2D (6d) model. The physics of the model was refined by accounting for the initial surge of particles and reducing the gap between the bucket cups and the boot wall. Inclusion of the particle surge flow and reduced gap gave the best predictions of commingling of all the tested models. This study showed that grain commingling in a bucket elevator boot system can be simulated in 3D and quasi-2D DEM models and gave results that generally agreed with experimental data. The quasi-2D (6d) models reduced simulation run time by 29% compared to the 3D model. Results of this study will be used to accurately predict impurity levels and improve grain handling, which can help farmers and grain handlers reduce costs during transport and export of grains and make the U.S. grain more competitive in the world market.

Page generated in 0.0677 seconds