Carlos B. Armijo

Using Cyclones Effectively at Cotton Gins

Cyclones are the most common type of emissions control device used in agricultural processing operations. Cyclones are efficient, reliable, low-cost, and require little maintenance. When used properly, cyclones effectively separate particulate matter from air streams, allowing compliance with state and federal air pollution regulations. Guidelines and techniques intended to help gin plant managers and operators determine if existing cyclones are correctly sized, properly constructed, and adequately maintained are reviewed. Methods presented are such that measurements can be made with minimal equipment and operating parameters determined with simple or no calculations.

Technical Note: Particulate Emission Profile of a Cotton Gin

Particulate matter (PM) is one of six criteria pollutants regulated by the Environmental Protection Agency (EPA) with National Ambient Air Quality Standards (NAAQS). In general, PM is the only air pollutant of concern emitted from cotton gins. The EPA has NAAQS for PM10 (particles with an aerodynamic diameter less than or equal to a nominal 10 µm) and PM2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 µm).

Collection Efficiency Evaluation of Baffle-Type Pre-Separator Configurations: Effects of Baffle Location and Inlet Velocities

Some cotton gins across the Cotton Belt use an abatement system consisting of a baffle-type pre-separator followed by cyclones to control the emissions from the cotton gins various exhausts. Very limited information exists in the literature which discusses the effects of baffle location and critical velocity on the pre-separators collection efficiency. In this study, a range of critical air velocities and loading rates were evaluated to determine the effect of baffle location of the pre-separators collection efficiency when using cotton gin waste. None of the treatments significantly affected the over-sized cyclone or over-all collection efficiency. The pre-separator collection efficiency was higher (81%) when the baffle placed at one-third the overall width of the pre-separator from the inlet than when placed at one-half (78%) or two-thirds (75%). The pre-separator collection efficiency was 79.4% at 18.3-m s-1 (3600-fpm) inlet velocity which was significantly higher than 78.2% at 20.3 m s-1 (4000 fpm) and 78.5% at 22.4 m s-1 (4400 fpm). Loading rate did significantly affect the pre-separator efficiency, but not to the extent of inlet velocity. The sieve analysis indicated that the pre-separator removed the majority of material larger than 180 µm; however, the pre-separator did allow a substantial amount of lint to pass through to the cyclone. The baffle-type pre-separator performed well in reducing the course material loading rate entering the cyclone.

Evaluating a Pneumatic Fractionator for Cleaning Ginned Lint

Abstract. The pneumatic fractionator has long been used to determine foreign matter content of seed cotton at the USDA-ARS cotton ginning laboratories. An experiment was conducted to evaluate the pneumatic fractionator as a device to remove foreign matter from ginned lint. No modifications were made to the standard device, except that air pressure to internal jets was reduced to 276 kPa (40 psi) from 517 kPa (70 psi). Three lint cleaning treatments after normal saw ginning were used: no lint cleaning, one standard controlled-batt saw lint cleaner, and cleaning with the pneumatic fractionator. Process times in the pneumatic fractionator were varied from 5 to 30 s. Foreign matter content (2.0 leaf grade and 253 counts g -1 AFIS total foreign matter) and color measurements (78.69 Rd and 10.20 +b) for the pneumatic fractionator were not statistically different from the saw lint cleaner (2.0 leaf grade, 257 counts g -1 AFIS total foreign matter, 79.08 Rd, and 10.18 +b). Length measurements of pneumatic fractionator cleaned lint were similar to or better than those of lint with no lint cleaning and, in most cases, better than lint cleaned with a saw lint cleaner. For example, upper- half mean length for pneumatic fractionator cleaned, no lint cleaning, and saw lint cleaner fiber was 29.7, 30.0, and 29.2 mm (1.17, 1.18, and 1.15 in), respectively. Also, the pneumatic fractionator produced about the same number of fiber entanglements as the saw lint cleaner. Processing time in the pneumatic fractionator had very little effect on fiber quality parameters with the exception that the 5 s processing time had the highest levels of foreign matter. These results showed that the pneumatic fractionator cleaned lint about as well as a saw lint cleaner, but maintained fiber length better.

Emissions from Gas-Fired Agricultural Burners

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

Manual Fractionation of MDTA-3 Trash Samples from Cotton Lint

13,945/tonne (

Efficiency of Current Seed-Cotton and Lint Cleaning Machinery at US Roller Gins

12,648/T) of NOx reduction. The SJVUAPCD has an upper limit of

Thermal Defoliation of Cotton

10,670/tonne (

Ginning a Cotton with a Fragile Seed Coat

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.

Harvesting and seed cotton cleaning of a cotton variety with a fragile seed coat.

One goal of lint cleaning at a cotton gin is to reduce the non-lint material to an acceptable level with minimal fiber damage. In an effort to improve lint cleaner performance, an initial study was conducted on lint collected before and after lint cleaning from 9 commercial gins across the cotton belt to characterize non-lint content. Samples from this study were first processed with a MDTA-3 (Micro Dust and Trash Analyzer 3, SDL Atlas, Stockport, England) to separate lint, trash, fiber fragments, and dust to determine the fractional composition of the original sample. The trash portion was retained for additional manual fractionation to determine the percent of material classified as seed coat fragments (SCF), motes, funiculi, sticks, leaf, bark, lint, and “other” material. Leaf, SCF, and sticks were the largest fractions accounting for 81% of the total trash sample. Overall, total trash decreased by 57% due to lint cleaning, and trash fractions remained consistent in samples before and after lint cleaning. Lint cleaning efficiency in terms of SCF was less than the overall cleaning efficiency, and lint cleaning efficiency for bark, mote, and other (all minor components) was higher than the overall cleaning efficiency. The lint cleaning efficiency for SCF was increased significantly when higher SCF levels were found before the lint cleaner, but this trend was not found for other fractions. Results of this experiment will help direct future studies to improve lint cleaning.