TAPPI TIP1101-02

The overwhelming majority of controllers used in the pulp and paper industry are simple PID controllers. For most control applications, a well designed and properly tuned PID control loop is all that is needed to achieve the control objectives. The majority of the PID control loops are tuned by a trial and error procedure. Some people actually develop a knack for tuning using this procedure. Unfortunately, most people do not. Until recently, if they used a tuning procedure at all, it was likely to be a quarter-amplitude-damping method such as the Ziegler-Nichols Method (1). However, many technicians engineers refrain from using this method because of the oscillations (cycling) that occur and the poor stability margin.This Technical Information Paper (TIP) describes a more applicable tuning method called Lambda Tuning which has been adopted s the preferred controller tuning method in the pulp and paper industry (2). It is based on simple process models that can be obtained by a sequence of simple bump tests while the loops are in manual mode.The step by step tuning procedures covered in this TIP were developed by the author as part of committee assignment for the System Design Subcommittee of the Process Control Committee.

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