Abstract. Because of the Federal Clean Air Act Amendments of 1990, the San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) began defining Best Available Control Technology (BACT) for NOx emissions from cotton gin drying system gas-fired burners in its jurisdiction. The NOx emission levels of conventionally used, direct-fired burners were unknown, as was how direct-fired burners would compare against newer lo-NOx burners or against the proposed SJVUAPCD NOx emission standard of 60 ppm or less. Replicated laboratory studies were designed to determine the emissions and fuel efficiency of both direct-fired and lo-NOx burner designs. NOx emission levels during the test averaged from 3 ppm for one of the lo-NOx designs to 36 ppm for a direct-fired burner when tested over four firing rates. An economic analysis of the specific cost of NOx reduction achieved by substituting a lo-NOx burner for a direct-fired burner showed an annual capitalized cost of $13,945/tonne ($12,648/T) of NOx reduction. The SJVUAPCD has an upper limit of $10,670/tonne ($9700/T) of NOx reduction to qualify for definition as BACT. Using this economic criterion, lo-NOx burners do not meet the definition of BACT for cotton gins for the SJVUAPCD, and, based upon conferring with industry and environmental specialists, would not for the rest of the United States.
The saw gin stand is the heart of the saw ginning system. From the initial filing of patents for the spiked tooth gin and the saw gin in 1794 and 1796 by Whitney and then Holmes respectively, the saw gin stand has predominated over early roller-type gins in the U.S. cotton ginning industry. These early saw gin stands were small, simple, that were manually fed hand-picked seed cotton and processed only a few hundred pounds of fiber per day. However, at this early stage, it was recognized that the gin stand had a huge impact on fiber quality and textile utility. These early saw gins tended to be single stand installations that consisted of a gin stand and a bale press. The basic operating principle of separating fiber and seed by pulling the cotton fiber through narrow slots that blocked the passage of the cottonseed in these early saw gins has not changed. However, the size and complexity of the saw gin stand and the ginning system, of which the saw gin is the heart, has changed by orders of magnitude. The most recent Cotton Ginners Handbook documented all of the manufacturers and specifications of U.S. saw gins that were being used in the cotton industry at that time. Subsequently, the saw gin has continued to evolve and some gin manufacturers are no longer in business whereas others have entered the field. This document provides the U.S. ginning industry the most recent information available on saw gin stands currently operating in the U.S.
Genetic diversity in modern upland cotton cultivars ( Gossypium hirsutum L.) is thought to be narrow, thus limiting genetic advance. Robust information on the genetic relatedness among currently grown cotton cultivars is lacking. The objectives of the present study were to field test a sample of elite commercial cotton cultivars, including many transgenic cultivars representing the major cottonseed companies, and to evaluate their genetic divergence using simple sequence repeat (SSR) markers. Eighty‐eight SSR primer pairs were chosen for genotyping that provided 177 SSRs. Jaccard's genetic similarity coefficients among 24 genotypes ranged from 0.694 to 0.936, with an average of 0.772, indicating that sufficient genetic diversity does exist within our sample of commercial upland cotton. Genetic similarities among cultivars from the same seed companies were generally higher than the mean of all cultivars and grouped into six major groups: two Deltapine (DP), one Stoneville (ST), one FiberMax (FM), and two New Mexico (NM) Acalas. One California Acala cultivar of New Mexico origin, developed by Phytogen (PHY), did not group with New Mexico Acala germplasm. Texas High Plains stripper type cultivars were distant from picker types and formed independent groups. Under New Mexico growing conditions, DP and ST cultivars yielded higher but produced lower fiber quality, while NM Acala cotton had lower yield but higher fiber quality. The PHY and FM cultivars were intermediate in cotton yield and fiber quality. Six SSR markers were identified to be significantly correlated with fiber yield or quality among the cultivars tested, providing impetus to validate the marker–trait associations.
Cotton always has trash associated with its fibers, which is known to affect processing efficiency. Rotor spinning is more sensitive to trash levels in cotton compared with ring spinning, the other major spinning system. Trash trapped in the rotor grove is typically pulverized cotton fiber and trash particles whose origins cannot be visually determined (e.g. leaf, fiber, bark, seed coat, etc.). New techniques or instruments are necessary to reliably provide rapid, consistent, and quantitative identification of cotton trash sources. The goal of this research was to identify the origins and to understand the impact of each type of pulverized substance on textile processing. Research has been done with infrared microscopy in order to confirm the utility of infrared mapping of cotton biological components. The mid-infrared region is between the wave numbers 4000 and 650 cm-1 and can be evaluated with Fourier-transform infrared (FT-IR) as a qualitative and quantitative analytical tool for organic substances. This study demonstrated the utility mid-infrared fingerprinting for qualitative identification of cotton contaminants. Mid-infrared spectroscopy was used to compare fiber and trash particles or dust with a spectral database of authentic samples to more accurately determine the source of spinning problems. Mid-infrared spectroscopy was able to predict the type of trash and demonstrated that the rotor dust accumulating in open-end spinning rotors appears to be hull and shale rather than seed coat fragments. This technique offers potential to study the influence of various types of trash on spinning efficiency.
Three cotton varieties were grown under furrow-irrigated conditions in southern New Mexico and hand-harvested so that individual bolls remained intact. The cotton bolls were conditioned in a controlled atmosphere and then subjected to a single cotton picker spindle operating at a speed of 1000 to 3000 rpm. Two spindle designs were studied: a 12.7-mm (-in.) round, tapered, barbed spindle and a 4.8-mm (3/16-in.) square spindle that was straight and smooth. Mass measurements were taken to determine the portion of seed cotton not picked and the portion that would be ejected from the spindle (fly-off). A force gauge was used to determine the peak force that was needed to pull the seed cotton from the spindle. Moisture content of the bolls used in the test ranged from 9% to 10% d.b. Results showed that the smaller, straight spindle was more aggressive in removing cotton from the boll. There was approximately twice as much fly-off from the barbed spindle than from the smaller straight spindle at any given speed. Fly-off also increased exponentially for each spindle type as the speed was increased. The peak force required to remove the seed cotton from the spindle ranged from 50% to 100% more for the smaller straight spindle than from the barbed spindle. For both spindles, the peak force requirement was approximately doubled each time the speed was increased by 1000 rpm, indicating an exponential relationship between speed and wrap tightness. Additionally, field tests were conducted for the 2005 and 2006 crop years by the USDA, Agricultural Research Service, Southwestern Cotton Ginning Research Laboratory in Mesilla Park, New Mexico.
