Abstract
This paper aims to present efficient efforts to optimize the proportional-integral-differential (PID) controller of clinker cooling in grate coolers, which have a fixed grate and at least two moving ones. The process model contains three transfer functions between the speed of the moving grate and the pressures of the static and moving grates. The developed software achieves the identification of the model parameters using industrial data and by implementing non-linear regression methods. The design of the PID controller follows a loop-shaping technique, imposing as a constraint the maximum sensitivity, Ms, of the open-loop transfer function and providing a set of PIDs that satisfy a range of Ms. A simulator determines the optimal PID sets among those calculated at the design step using the integral of absolute error (IAE) as a performance criterion. The combination of a robustness constraint with a performance criterion, Ms and IAE respectively, leads to an area of controllers with Ms belonging to the range of 1.2 to 1.35. The IAE is between 4.2% and 4.8%, depending on the set-point value. PID sets located near the middle of this area can be chosen and implemented in the cooler’s routine operation.
Highlights
This paper aims to present efficient efforts to optimize the proportional-integral-differential (PID) controller of clinker cooling in grate coolers, which have a fixed grate and at least two moving ones
The effectiveness of clinker cooling is linked to two factors: (a) the recovery of heat from the material entering the cooler and (b) its cooling rate, because rapid cooling helps to increase the quality of the product [1]
The results show that dynamic matrix control (DMC) can forecast the changes in grate pressure and allow the operator to adjust the grate speed
Summary
The operating system of the cooler is PCS7, Version 6.1, by Siemens AG (Munich, Germany). The software extracting data from the plant process server is PI, Version 3.2.0.0, by OSIsoft (San Leandro, CA, USA). The PI client acquires the process data with a sampling period of 5 s and stores them on the PI server. The data saved in this server constitute the plant database. The developed software, in C#, extracts from the PI server, using specific queries, specified data of the cooler with a 20 s period, and stores them in a Structured. Afterwards, it processes the SQL data, attempting to determine the optimal PID sets constituting a PID optimizer. Data extraction from PI and storing to SQL; Data extraction from SQL and determination of the best models; PID design; Simulation of the process to find the optimal PID gains
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