|Boykin Jr, James
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2005
Publication Date: 10/1/2005
Citation: Boykin Jr, J.C. 2005. The Effect of Dryer Temperature and Moisture Addition on Ginning Energy and Cotton Properties. Journal of Cotton Science. Vol. 9: 155-165.
Interpretive Summary: U.S. cotton production approaches 20 million bales annually, most of which is exported. It is important that the quality of this cotton keeps up with the changing demands of the industry. Fibers must be long and uniform, as well as strong, to process smoothly in a textile mill. One issue that has been persistently important in the ginning and textile industry is processing problems associated with cotton fiber damage that occurs when the moisture of the cotton is improperly conditioned in the cotton gin. Cotton fibers are weaker when they are dry and more prone to breakage. On the other hand, trash particles are more easily removed from cotton in the gin after some drying. One approach to solving the problem has been to dry cotton for cleaning and restore moisture before ginning. Several different types of cotton were ginned in Stoneville, MS through a typical sequence of machines including a cotton dryer and moisture restoration equipment. This paper reports changes in cotton fiber properties due to moisture conditioning in the gin. Additionally, the gin stand energy consumption was evaluated to help understand the mechanism of cotton fiber breakage. The gin stand was found to break fibers, and a corresponding change in energy consumption was found. This relationship between fiber breakage and energy consumption will be vital to modifying current moisture conditioning processes and reducing fiber damage. Implementation of this knowledge will increase the competitiveness of U.S. cotton.
Technical Abstract: Fiber damage can be reduced during ginning by minimizing dryer temperatures and restoring moisture to over-dried fibers. This paper reports the effects of moisture conditioning on fiber damage and gin energy consumption. Moisture restoration raised bale weights by over 1% (5 pounds) as determined at the gin stand feeder apron, but this amount fell to 0.53% (2.7 pounds) by the time the cotton reached the bale. Reducing dryer temperatures 50 ºC (90 °F) raised bale weights by 0.81% (4.0 pounds). Moisture addition reduced energy consumption by the gin stand by 1.4% (0.08 kWh per bale), regardless of dryer temperature or the moisture content of the cotton. As dryer temperatures were raised and lint moisture dropped to 5%, energy consumption increased. However, energy consumption began to decrease at higher dryer temperatures with lint moisture contents below 5 %. These changes were attributed to changes in fiber strength and cohesive properties of the fiber. Minimizing dryer temperatures and adding humidified air above the gin stand were thought to relieve stresses on the fiber and reduce fiber damage.