双重控制算法在复烤回潮生产线的应用
Application of Dual Control Algorithm in Conditioning Section of Redryer
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摘要: 为解决复烤回潮生产线出口含水率控制过程中,高压水泵变频、混合水流量、混合蒸汽3种调节方式相互独立而存在控制精度不足的问题,在预测PI控制算法的基础上,提出了含水率双重控制方案。高压水泵变频调节对含水率的影响最直接,调节速度快,作为主控制器;混合水流量调节和混合蒸汽调节用于改变回潮区的湿度场,调节速度较慢,作为副控制器。运行效果表明,以预测PI算法为主体,以改进的双重控制算法为框架的回潮区控制算法,有效提高了复烤出口含水率的控制精度,95%的时间控制在设定值的±0.2%,能够及时协调高压水泵、混合水、混合蒸汽之间的关系,避免了高压水泵变频调节达到饱和而没有调节余地的问题,消除了操作人员的人工干预,提高了复烤设备的自动化水平。Abstract: The regulation of high pressure water pump, mixed water flow and mixed steam in redryer's conditioning section was independent of each other, which resulted in low control accuracy of moisture content in output redried tobacco. Therefore, a dual control means was proposed on the basis of predictive PI control algorithm. The controller for frequency conversion of the water pump motor was used as a main controller because of its direct and quick effects on tobacco moisture content, and the controllers for mixed water flow and mixed steam were taken as subsidiary controllers to change the humidity in conditioning section due to their slow regulation speeds. The results of practical running showed that the control algorithm combining predictive PI algorithm with improved dual control algorithm effectively improved the control precision of moisture content in output redried tobacco, which was controlled within the range of ±0.2% of the setting value in 95% of processing time. The relationships between high pressure water pump, mixed water and mixed steam were timely coordinated, the regulation of pump motor's frequency conversion beyond its limits was avoided, operator's interference was also eliminated, and the automation level of redrying equipment was improved.
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