Location: Cotton Production and Processing Research2021 Annual Report
OBJECTIVE 1: Develop commercially viable methods and technologies for use before ginning that reduce harvest costs, preserve fiber/seed quality, enhance the utilization of production/harvest/gin data, and prevent/minimize contamination of upland cotton. Subobjective 1A: Assessing the influence of seed cotton storage in round modules on lint and seed quality. Subobjective 1B: Improving the cleanliness and quality of stripper-harvested cotton through improved field cleaning systems. Subobjective 1C: Development of equipment to detect and remove contaminants from cotton during the harvesting process. OBJECTIVE 2: Enable commercially preferred technologies/methods/strategies for use in ginning upland cotton that improve cleanliness of seed cotton and lint, detect/remove contamination, preserve fiber quality, and reduce financial costs. Subobjective 2A: Development of equipment to detect and remove contaminants from cotton in the harvest and ginning processes. Subobjective 2B: Improving cotton fiber length distribution through novel lint cleaner design. OBJECTIVE 3: Develop commercially viable post-ginning technologies/techniques that enhance the storage and utilization of upland cotton products/coproducts/byproducts and reduce the environmental footprint of cotton production/processing. Subobjective 3A: Development of a commercially viable mechanical cottonseed delinting system to remove cotton linters and produce planting quality seed, without the use of chemicals. Subobjective 3B: Reducing particulate emissions from cotton ginning through improved pollution abatement device design using computational fluid dynamics (CFD) and laboratory testing. Subobjective 3C: Develop and evaluate the use of cotton plant constituents and other natural fibers in the manufacture of composite materials.
This five-year project plan addresses critical pre-ginning, ginning and post-ginning issues facing cotton producers and processors in the United States. Our plan of work is based on an interactive research approach which is focused on the development of processes and systems for preserving cotton quality during infield storage and ginning, removing foreign material and contaminants from seed cotton during harvesting and ginning, reducing particulate emissions from ag operations, reducing the environmental impact of acid cottonseed delinting, and increasing the value of cotton byproducts though composite materials. The research plan detailed herein addresses the development of new technologies, methods, and strategies for reducing the economic and environmental costs of cotton harvest, ginning, and post-gin processing of upland cotton and cotton by-products. Commercial viability of the research is a key component of any problem solution.
Objective 1, Subobjective 1A: A review of the existing literature related to moisture content and foreign matter effects on post-storage cotton fiber and seed quality was conducted. The available literature focused on seed cotton storage in storage houses, ricks, trailers, and rectangular modules. Limited published information is available on seed cotton storage in plastic wrapped cylindrical modules, and that which is available, did not investigate the effects of high initial moisture content on post-storage lint and seed quality. The information obtained from the literature review was used to develop a protocol for evaluating the effects of seed cotton moisture content on the quality of cotton fiber and seed after storage in cylindrical modules. Protocols have been developed to investigate these effects under small-scale laboratory and large-scale commercial conditions. Cooperative research in the United States and Australia has been planned. Subobjective 1B: Testing was conducted to simulate the operation of a new field cleaner design under laboratory conditions using a current production-model field cleaner. The performance observed under laboratory conditions indicated substantial improvements in foreign matter removal efficiency while reducing the amount of seed cotton loss relative to the current production-model machine. The simulation experiments led to the design and construction of several prototype field cleaners that were installed and tested on cotton strippers under field conditions. Experiments were designed and conducted under field conditions to evaluate the performance of the new field cleaner relative to the current production-model machine. The results of the field experiments indicated an improvement of cleaning efficiency of 20% over the current field cleaner design with equal or slightly less seed cotton loss. Subobjective 1C: One of the key impediments in the development of a machine-vision classifier for outdoor use is that natural outdoor lighting is continuously variable and ranges from a color temperature of 3,000 Kelvin (K) to 30,000 K. This lighting variation has a significant detrimental impact on the ability for a classifier to detect objects. Further it is known that the human visual system is much more adept at being able to detect objects of interest against like colored backgrounds. In efforts to develop a lighting independent classifier, a literature review was conducted on machine vision algorithms designed for color agnostic detection of objects using texture metrics. The classifiers under consideration have shown the ability to provide classification based upon use of different characterizations of texture variation. The most promising approaches that were found in the literature are adaptive thresholding, Gabor filter banks, pixel-local entropy (disorder) metrics, and deep-learning convolutional-neural-networks (CNN) models. Experiments were planned and are underway to test various texture-based classifiers for use in detection of plastic contamination against like colored backgrounds as well as when plastic is embedded in cotton, similar to the situations that occur during harvest and ginning. Objective 2, Subobjective 2A: A literature review was conducted on machine-vision classifier algorithms that could be used to detect plastic contamination in cotton. Literature has also been searched for extraction methods that have potential for use in removing embedded plastic from freshly harvested seed-cotton. The most promising of the approaches suggested by the literature are high-speed robotics and pneumatic ejection using blow-off nozzles and air-knives. Based upon the most promising approaches suggested in the literature, experiments have been designed, software was written to test classification algorithms, and laboratory testing has begun to examine performance efficiency for machine-vision algorithms and plastic contamination extraction methods. Subobjective 2B: Lint cleaning using saw-type lint cleaners is an aggressive process that leads to fiber breakage and reduced staple length. The cleaning mechanism used by air-type lint cleaners has been shown to be a much gentler method of removing foreign material from cotton fiber although much less efficient than the mechanism used by saw-type lint cleaners. A multi-stage air type lint cleaner prototype was designed and tested under small scale conditions. Testing results of the prototype machine indicated that combining up to three stages of air lint cleaning removed significantly more foreign material than only one stage alone while having minimal to no effect on fiber length characteristics. Additional development is planned to scale up the prototype for testing under commercial ginning conditions. Objective 3, Subobjective 3A: The mechanical cotton seed delinting system was evaluated, and the results have been presented at stakeholder meetings and conferences. Testing of the prototype system revealed a balance between higher conveyor speeds and seed damage. The higher speeds improved residual lint removal but also resulted in higher visible mechanical damage (VMD) to the cottonseed. Likewise, the addition of “kickers” (strips of wire brush inserted between the auger flights of the conveyor) improved lint removal but also increased VMD. It is believed that a balance between VMD and maximum lint removal can be achieved with some additional adjustments of the distance between auger flights and the brushes along the bottom of the conveyor. These and a few other items will be evaluated in future testing as soon as all staff is able to return to the offices/lab. Subobjective 3B: Baffle type pre-separators are used in cotton gin particulate matter abatement systems to balance air flows and reduce the loading rate of large foreign material from multiple cleaning system lines before final control devices (cyclones) are implemented. Reducing the loading rate of large foreign material from pneumatic lines conveying trash from various cleaning processes in the gin reduces wear on more expensive final control devices. A literature review revealed minimal published work on the design and predicted performance of baffle-type pre-separators and no work was found that discussed potential design improvements to enhance collection efficiency for particulate matter. Computational fluid dynamics modeling of a baffle type pre-separator was conducted and indicated that the use of an internal skimmer plate positioned along the back wall of a device may help increase collection efficiency for small diameter particles while maintaining the ability for a pre-separator to remove large foreign material from the air stream. The positioning of this plate is a critical design element and additional modeling and testing is needed to refine and confirm these results. Testing on a prototype baffle-type pre-separator has been planned. Subobjective 3C: Review and evaluation of natural fibers was completed with assistance from a cooperator from Montana State University. The review revealed that the best option is for fibers to be layered onto existing composites if they are being added after the composite has been formed due to the cost associated with modifications needed for insertion of fibers. Ideally, fibers should be incorporated into a composite matrix ahead of time when manufacturing but when adding fibers to improve physio-mechanical properties, overlaying onto the composite is currently the most viable alternative. The next question is which fiber or fiber blend would be the most efficacious to improve the desired physio-mechanical property being sought.
1. A new field cleaner to enable the next generation of cotton harvesters. Stripper-type cotton harvesters are used to harvest about 7 to 10 million bales, or half of the cotton crop produced in the U.S. annually. Recent design changes to incorporate the capability to form seed cotton modules on the harvester have increased the purchase cost of stripper harvesters from about $250,000 to around $800,000. To allow stripper harvesting to remain as an economically viable option for U.S. cotton growers, increased machine purchase costs must be offset by increased harvest productivity and reduced harvest-time labor and supplemental equipment requirements. In response to the need for greater harvest productivity, ARS engineers in Lubbock, Texas, worked with engineers under a cooperative research and development agreement (CRADA) to develop and evaluate the performance of a new field cleaner for use on stripper harvesters. The new machine increased material processing capacity by 25% while improving cleaning efficiency by 20%. In addition to meeting new processing capacity goals, the new machine increased the value of cotton harvested by over $5 per bale compared to the current production model machine resulting in an expected $35 to $50 million of additional annual revenue for U.S. cotton growers.
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Pelletier, M.G., Holt, G.A., Wanjura, J.D. 2021. Cotton gin stand machine-vision inspection and removal system for plastic contamination: software design. AgriEngineering. 3(3):494-518. https://doi.org/10.3390/agriengineering3030033.
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