Airflow through Granular Beds packed with Cottonseeds

The study is concerned with local exhaust ventilation systems for dust control in the hulling-separation process in cottonseed oil mills. Experiments were carried out to study the parameters that influence the pressure drop and mean velocity of airflow through a packed bed of cottonseeds, both bare and fuzzy. The experimental facility included a blower, ducts, and a granular bed filter filled with cottonseeds connected to the ducts. An orifice flowmeter and a Pitot tube were installed in the duct and connected to electronic pressure transducers. A transducer was also used for measurements of the pressure drop across the packed bed filters. The pressure transducers were connected to a computer with data acquisition software. The parameters varied during the experiments were the presence and absence of cottonseed fuzziness, the layer thickness of the packed cottonseeds, and the airflow rate. The measured data showed that pressure drop increases with increasing airflow rate, presence of fuzziness of the cottonseeds and thickness of the bed layer. An equation that relates the pressure drop to the airflow rate is proposed based on the Carman equation and coefficients obtained by regression analysis. Graphs plotted in accordance with this correlation equation compare favourably with most of the measured data.