Author
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Hardin Iv, Robert |
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Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings Publication Acceptance Date: 1/4/2014 Publication Date: 3/6/2014 Citation: Hardin IV, R.G. 2014. Effect of Seed Cotton Cleaner Speeds on Machine Performance. National Cotton Council Beltwide Cotton Conference.January 6-8, 2014. New Orleans, LA. 584-589. Interpretive Summary: Cotton gins use several different types of machines to remove foreign matter from the cotton. This foreign matter consists primarily of parts of the cotton plant such as leaves, sticks, carpels (commonly referred to as burrs or hulls), and immature seeds (motes). Seed cotton cleaners are used before the gin stand, where the fiber is removed from the seed, and include cylinder cleaners and stick machines. Cylinder cleaners have rotating spiked cylinders that convey the seed cotton across bars with small gaps between them. Smaller particles, such as leaves and soil, fall through the gaps, generally aided by air flow. Stick machines have rotating cylinders with saw teeth attached. The seed cotton attaches to the saw teeth, while larger foreign matter particles are thrown off by centrifugal force and removed from the seed cotton. Gins also use lint cleaners after the gin stand to remove the remaining small particles of foreign matter. Most gins have two stages of lint cleaning installed, but often only use one, as lint cleaners remove some good fiber with the foreign matter and reduce fiber quality. The desired level of cleaning depends on the color grade of the fiber. Further cleaning does not significantly increase the value of the cotton per pound, but will often decrease the total value due to the additional good fiber removed. Significant economic penalties are incurred if the desired level of cleaning is not achieved. In a commercial gin, usually the only way to adjust the level of cleaning during operation is to use or bypass the stick machine or second lint cleaner. These options may provide more or less cleaning than is optimum. Furthermore, gins often process cotton that can not be cleaned to the desired level using all cleaning than equipment in the gin. The penalty varies with other quality parameters, but can be more than $10/bale. Additional cleaning machines could be installed, but cost over $70,000 each. A potential solution to this lack of adjustability of cleaning machines and need for occasional additional cleaning is to vary the speed of the spiked cylinders on a cylinder cleaner or the saw cylinders on a stick machine. The cost of a variable-speed drive for the electric motor on a cylinder cleaner or stick machine has decreased significantly in recent years. A seed cotton cleaner could be retrofit with variable speed capability for less than $2500. Past research has indicated that improved cleaning may occur when seed cotton cleaners are operated at higher speeds; however, a greater range of machine speeds need to be tested and the amount of fiber lost when the machines are operated at higher speeds needs to be evaluated. Five cylinder cleaner speeds and five stick machine saw speeds, ranging from the recommended factory setting to double that speed, were tested with four cotton varieties. Compared to the standard speed, the highest cylinder cleaner speed resulted in 70% more material removed from the first stage cylinder cleaner and more than twice the material removed from the second stage cylinder cleaner. However, the combined fiber loss from both cylinder cleaners increased from 0.66 lb/bale to 6.6 lb/bale. Doubling the stick machine saw speed only increased material removal by 20%, and fiber loss samples from the stick machine have not yet been analyzed. Seed cotton cleaner speeds did not affect the lint turnout (mass of lint produced divided by initial mass of seed cotton) or any of the quality parameters used by USDA-AMS classing offices to determine the value of the fiber. A primary explanation for this result was that even a minimal amount of cleaning produced optimal leaf grades (classing office measure of foreign matter content). This study will be repeated with cotton that is harder to clean or contains more foreign matter to more closely simulate scenarios where adjustable parameters on a cleaning Technical Abstract: Past research has shown that increasing seed cotton cleaner speeds can improve cleaning efficiency. Advances in process control may make cleaner speed control feasible; however, an improved understanding of seed cotton cleaner performance at higher operating speeds is needed. The objectives of this study were to determine the effect of cylinder cleaner speed and stick machine saw speed on cleaning performance and fiber loss and to evaluate how cleaner speeds affect fiber quality and turnout. Seed cotton was processed through the minimum recommended sequence of ginning machinery. Four cultivars were processed at five cylinder cleaner speeds and five stick machine speeds. Samples were collected from the seed cotton for determining moisture and foreign matter content. The material removed by the seed cotton cleaners was also sampled to determine fiber loss. HVI and AFIS samples were collected before and after the lint cleaner to evaluate fiber quality. Weights of all process streams were recorded to determine the proportion of material removed by each cleaner and lint turnout. Higher cleaner speeds increased material removal by the cleaner. Cylinder cleaner fiber loss was increased at higher speeds. Samples for determining fiber loss from the stick machine have not been analyzed. Leaf grades were not affected by cleaner speed; however, all speeds produced desirable leaf grades, with average leaf grades of 2.1 before and 1.2 after the lint cleaner. Higher cylinder cleaner speeds reduced AFIS dust and trash measurements, but other HVI and AFIS fiber quality parameters were not significantly affected by cleaner speed. Turnout and loan value were also not affected by cleaner speed. Further research is needed with cotton that is more difficult to clean or contains higher levels of foreign matter. |
