FBD双回路控制系统的设计应用

Design of Double Loop Control System in FBD

梗丝干燥流化床FBD(Fluid Bed Dryer)含水率控制系统中3个区的温度控制是纯滞后大惯性环节,存在系统响应速度慢、受到扰动时波动大、达到稳定时间长等问题。为此,设计了以风量控制为主、温度控制为辅的双回路含水率控制方式,含水率波动较小时采用风量调节,含水率偏差较大时采用热风温度调节,有效改善了"干头"和"干尾"时间长、纯温度控制系统滞后大、易扰动的现象,加快了系统的响应速度,提高了系统的稳定性。梗丝含水率的平均合格率由改造前的83.88%提高到95.56%,保证了梗丝的工艺质量。

The fluidized bed cut stem dryer is a system of large thermal inertia, the control system which controls the moisture content of dried cut stem by regulating the temperature in the 3 drying sections of the dryer has the disadvantages of slow response and large fuctuation to disturbance. Therefore, a double loop moisture content control system based on air volume regulation and aided by temperature regulation was designed, whereby, air volume was regulated when moisture content fluctuated within a limited range, while air temperature was regulated when moisture content fluctuated beyond that limited range. After improving, the over-dried tobacco during start-up and run-down was reduced, the resistance to disturbance, response speed and stability of control system were improved effectively, and the average rate of cut stem up to the standard of moisture content increased from 83.88% to 95.56%.