MINIMIZATION OF PAPER MACHINE DRYING COSTS THROUGHT THE USE OF ADVANCED PROCESS CONTROLS, PaperCon 2010 Conference

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This paper describes opportunities found and model predictive control (MPC) application implemented at the Longview Fibre paper mill in Longview, Washington to reduce the energy consumption in paper making processes. Results achieved with MPC are described in the paper.

After mechanical dewatering of the stock in the paper machine wet end, the rest of the water to be removed from the paper produced is typically done in the drying section of the paper machine using thermal energy available from steam. The drying section is divided in multiple sub sections and today’s paper machine operators have many handles at their disposal to achieve final paper dryness produced in the drying sections. Examples of these handles include dryer pressures, hood temperatures, blow through rates and fan speeds. Each of these handles has different operating/efficiency curve, i.e. quantity of water evaporated per unit of energy used. Even for most experienced operators it is very difficult to optimize economically the total energy use in the drying section.