Automatic metering feeder control
In chemical fiber production, it is often required that solid, powdered raw materials be fed into the process equipment at constant pots. If the charge is intermittent (eg PVA dissolution in PVA production, dissolution of nylon basin in nylon production, etc.), the dosing is done automatically or manually by means of a weigh scale. If the dosing is continuous (eg washing of vinylon production Section to the dissolution machine delivery PVA), in order to feed a balanced feeder, the unit of time the amount of material should be kept constant, for which the amount of feed required for the implementation of automatic control. Here, a specific example of the automatic feeding controller controlling the feeding of the PVA to the dissolver is as follows.
The PVA, which is planted on the basin conveyor from the center of the PVA, has a unit weight of Q (kg / m). Obviously, the weight of this unit length t is related to the pick level in PVA. When the material level is high, the blanking material will be more, the material thickness will be larger, and Q will be larger. On the contrary, Q will be smaller. From Figure 2-13 we can see that the speed of the middle tank feeding is synchronous with that of the metering conveyor. When the conveyor speed is two (two / min) That the conveyor belt thickness, that is, the unit length of the weight basin Q, from the speed of the conveyor belt speed.
When Q fluctuates (the system is superior), as long as the change of feed speed v, you can make the feed torque W constant. PVA automatic feeder control is based on this basic principle. Therefore, changing the feed rate library, that is, as a system of control.
When △ Q is positive (weight per unit length increase), to reduce or eliminate the change of feeding basin W, we must reduce the conveyor speed, that is, Take what can be positive.
Second, commissioning tw test of Automatic metering feeder
In order to form a closed-loop control system, must first measure the controlled variable W, use it as a feedback signal into the regulator, the regulator output signal and then through the speed controller to change the speed of the drag conveyor motor to change the conveyor speed ,, The controlled variable (feed egg) W is kept constant.