Derek P. Whitelock

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.

EFFECTS OF CYCLONE DIAMETER ON PERFORMANCE OF 1D3D CYCLONES : CUTPOINT AND SLOPE

Cyclones are a commonly used air pollution abatement device for separating particulate matter (PM) from air streams in industrial processes. Several mathematical models have been proposed to predict the cutpoint of cyclones as cyclone diameter varies. The objective of this research was to determine the relationship between cyclone diameter, cutpoint, and slope of the fractional efficiency curve (FEC) based on empirical data. Tests were performed comparing cutpoints and FEC slopes of 15.24, 30.48, 60.96, and 91.44 cm (6, 12, 24, and 36 in.) diameter cyclones with poly-disperse PM having an aerodynamic mass median diameter near 10 µm. The mass of PM collected by the cyclones and the mass and particle size distributions of PM that penetrated the cyclones were used to determine each cyclones FEC, characterized by a cutpoint and slope. The cutpoints of cyclones showed no relationship to cyclone diameter, while the slope of the cyclone FECs increased as cyclone diameter increased. Statistically different collection efficiencies were observed among the 30.48, 60.96, and 91.44 cm (12, 24, and 36 in.) diameter cyclones. None of the previously published mathematical models analyzed in this article accurately predicted cyclone cutpoint.

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.

Formation of Neps in Pima Cotton during Mechanical Harvesting

Neps are a major concern as American Pima cotton competes with other extra-long staple (ELS) cotton at the textile mills. A nep is defined as a tight knot-like mass of unorganized fibers. Research has showed that 27% of the total increase in nep counts from the boll to the bale press occurs during spindle-harvesting of ELS cotton. The objective of this research was to determine the contribution of the spindle action and doffing action to nep counts in mechanically harvested Pima cotton. This paper details the background, and methods and procedures used for the research. Fiber analyses have not been completed. Therefore, no results are available at this time.

Preliminary Results of a Series Cyclone Test

Cyclones are commonly used in the processing industry as primary particulate emissions abatement devices. A study was conducted to evaluate the effectiveness of one, two, three, or four 1D3D cyclones, in series, on airstreams heavily loaded (236 g/m3) with fine particulate (mass median diameter <10 µm). The overall efficiency of a single cyclone (91%) was significantly lower than that of the series cyclone configurations (98%). Also, a single cyclone was consistently less efficient (91%) and had a higher static pressure loss (1356 Pa[5.4 in. w.g.]) than the No. 1 cyclone in the series configurations (94% efficiency and 881 Pa [3.5 in. w.g.] static pressure loss). Particle size distributions showed that there was a significant shift toward smaller sized particles in dust captured by the cyclones (8.78 to 1.86 µm) as the number of series cyclones increased from one to four. A secondary cyclone increased overall efficiency significantly with an insignificant rise in static pressure loss, while additional cyclones raised efficiency only about 1% more and increased pressure losses by 150%.

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.

Cyclone Energy: Impact of Inlet Velocity and Outlet Évasé Designs

Abstract. Because electricity generation produces emissions, reducing cyclone pressure drop has the potential to benefit the environment. Enhanced 1D3D cyclones common in the cotton ginning industry were tested with various A©vasA©s, over a range of inlet velocities. With A©vasA©s it was possible to reduce the cyclone portion of energy consumption by 5%. It was possible to reduce the cyclone portion of energy consumption by 50% by reducing inlet velocity 28%. Particle size distribution analysis of cyclone emissions showed little change in PM 10 and PM 2.5 over this range of inlet velocities. If emissions at power generating facilities is balanced against emissions at rural agricultural processing facilities, then it is probable that increasing regulatory flexibility would benefit the environment more than more stringent regulations.

Manual Fractionation of MDTA-3 Trash Samples from Cotton Lint

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.

Effects of Cyclone Diameter on Performance of 1D3D Cyclones: Collection Efficiency

Cyclones are the most commonly used air pollution abatement device for separating particulate matter (PM) from air streams in agricultural processes, such as cotton gins. Several mathematical models have been proposed to predict the performance of cyclones as cyclone diameter varies. The objective of this research was to determine the relationship between cyclone diameter and collection efficiency based on empirical data. Tests were performed comparing cyclone collection efficiency of 15.24-, 30.48-, 60.96-, and 91.44-cm (6-, 12-, 24-, and 36-in.) diameter cyclones with poly-disperse PM having an aerodynamic mass median diameter near 10 im. The mass of PM collected by the cyclones and the mass of PM that penetrated the cyclones was used to determine the collection efficiency of each cyclone. The collection efficiency of cyclones decreased nonlinearly as cyclone diameter increased with statistically different collection efficiencies observed among the 30.48-, 60.96-, and 91.44-cm (6-, 12-, 24-, and 36-in.) diameter cyclones. None of the mathematical models analyzed in this paper accurately predicted cyclone performance.