Practical Airflow Rates in Shelf Dryers for Seed Cotton: In Cooperation with the Mississippi Agricultural and Forestry Experiment Station

A study conducted to evaluate the effect of heated-air velocity and air-to-cotton ratio on the amount of moisture evaporated from seed cotton in cotton gin dryers established minimum practical airflow rates for the dryers. The results can be used to reduce energy requirements in the transport and drying of cotton at gins and in setting guidelines for gin-dryer designs. Machine-picked seed cotton at moisture contents ranging from 9 to 20 percent was conveyed through a two-tower dryer shelf system using a drying temperature of 230 0 to 240°F, air velocities of 742 to 1,497 ft/min, and air-to-corton ratios of 8.4 to 36.2 ft3 air/lb seed cotton. Results showed that an air velocity of 1,200 ft/min in the dryer at a ratio of 13.2 ft3 air/1b seed cotton is sufficient to convey the dampest cotton expected at the gin through tower dryers. A velocity of 1,000 ft/min at a ratio of 11.4 ft3/lb can be used on normal cottons. Limiting the airflow to that required to convey seed cotton did not significantly affect the moisture evaporation rate.