Control of Tobacco Moisture Content in Thin Plate Cylinder Dryer Based on Exhausted Air Volume

To reduce the influences of temperature fluctuation inside cylinder dryer on the aroma of processed cut tobacco, the relative variables influencing moisture content in tobacco during the drying process were analyzed, a control method for moisture content in dried cut tobacco based on exhausted air volume from the cylinder while retaining the thin plates and hot air at constant temperatures was proposed. A control model was developed, the effects of tobacco input rate and its moisture content on the humidity of the exhausted air, and the relationship between the opening of the exhausted valve and exhausted air volume were studied. The self-adapting PID expert control strategy for valve was adopted to implement the control process, and PID value was set to prevent the moisture content in tobacco from over regulation or fluctuation. The results showed that changing exhausted air volume could control the moisture content in dried tobacco, the response time was shorter for valve than that for steam heating' and regulating valve was faster than regulating the temperature of thin plate or hot air. The moisture content in tobacco was controlled and regulated rapidly, which ensure the consistence of cut tobacco aroma during drying and avoid the discrepancyof tobacco quality in production.