Helical speed reduction gearbox H3 acoples flender H3-CH-8B

Flender/Flender Gear Units/Helical speed reduction gearbox H3

d by disturbances. In dryingprocess the most important controlled variable is the product moisture content. 2.3 Dryer Control System Principles There are several principles that can be applied successfully to set up dryer control system for drying processes. Manual, feedback, feedforward, model-based, and computer-based direct digital control are considered. 2.3.1 Manual Control In practice in some cases there is no way to apply automatic control solutions to maintain the drying process. In such cases manual control is necessary. In manual control, expertjudgment of the operator is relied on for judging the end point and setting the initialthroughput of the drying process (Fig. . The dryer manual control schedule may be described by the following sequence (1,2,: 1. Turn on the dryer. 2. Set the initial throughput.3. Measure the output moisture content and compare the measurement with the desired value. 4. On the basis of the difference between the desired and the measured moisture content values, make adjustments to the manipulated variable() (.., energy input, feed rate) to maintain the desired moisture content. Manual control is simpler and less expensive and requires less expertise than automatic control. It can be applied to small-scale plants (mainly batch systems) and to easy-to-drymaterials. It is also labor-intensive. 2.3.2 Feedback Control The principle of feedback control is one of the most commonly used control strategies in drying process control. The main function of dryer feedback controller is to hold thecontrolled variable at desired value or set point. Fig. 2 Scheme of manual control of the drying process. Control Aspects 8 Fig. 3 Scheme of feedback control of the drying process. The control system receives measured signal of the controlled output variable (.., moisture content) and compares it with the set point value, which generates an error signal.On the basis of the error signal, the controller changes the value of the manipulated vari