| Energy consumption reduction is currently becoming focus in papermaking industry.The energy consumption of dryer section accounts for more than half of the whole papermaking process and it comes from inside of dryer(steam condensate thermodynamic system)and outside of dryer(hood ventilation thermodynamic system).For a long time,most of the research is to optimize the energy consumption of two systems separately.To further reduce energy consumption and increase energy efficiency of paper machine dryer section,the cooperation system of the two parts is put out.The energy consumption of steam condensate system and hood ventilation system are counted together to recycle the secondary thermal energy.This thesis takes the dryer section of high strength fluting paper machine paper line as controlled object,and is funded by the project of key science and technology innovation team in Shaanxi province.The study of technology application for prediction model and optimal control strategy of dryer section energy consumption is carried out.The main work is presented as follows.Ⅰ.Design of cooperation system for dryer section energy consumption of multi-dryer paper machine.Thermodynamic system of paper machine dryer section is reviewed.Through comparative analysis,the different steam supply schemes of steam condensate system and hood ventilation system are introduced and their merits and demerits are given.For increasing the energy efficiency,the rest of secondary steam and condensate of steam condensate system is used to heat the supply air of hood ventilation system,and the energy consumption cooperation system for multi-dryer paper machine dryer section is built.Ⅱ.Modelling of energy consumption prediction of cooperation systemEnergy consumption cooperation system of high strength fluting paper machine is built based on the drying process of high strength fluting paper andthe energy consumption cooperation system of multi-dryer paper machine.The system is divided into the calorifier,each dryer sections and ventilation system according to thermodynamic process.Their thermodynamic process is modeled on the basis of heat conversation and mass conversation.Then,the whole energy consumption prediction model is derived.By comparing with the actual steam consumption in paper mill,the error of model calculation is under 10%,which indicates that the model calculation is consistent with the actual situation.Ⅲ.Research on energy consumption optimization of cooperation system.With the lowest energy consumption cost as optimization object,the parameter requirements of paper drying process as the constraint conditions,energy consumption optimization model of high strength fluting paper machine dryer section is built based on energy consumption prediction model and nonlinear programming in operation research.The model is solved by genetic algorithm to get the optimal value of main setting parameter which have great influences on energy consumption,like the dryer inlet pressures,the dew point temperature and ventilation etc.After optimization,the energy consumption cost of dryer section can be reduced by 9.63%,and the saving effect is obvious.Ⅳ.Implement of energy consumption cooperation control system based on S7-300 PLCControl strategies are designed according to the characteristics of control loops of each optimal setting value.Based on the hardware of Siemens S7-300 PLC and software of WinCC & Step7,the DCS of cooperation control system for energy consumption of high strength fluting paper machine dryer section is implemented to optimize the energy consumption.The cooperation system for energy consumption of high strength fluting paper machine dryer section and the optimization of control strategy in this paper has been applied in a high strength fluting papermaking production line in Zhejiang.The application results show that the energy consumption prediction model,optimization model and control system have a better effect,and the energy consumption cost can be reduced effectively. |
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