摘要：With the development of society and the improvement of people's living standards, tissue paper has become an essential consumer goods in our daily life. However, under the background of the global energy shortage, the fierce competition of market and the strict requirements of environment, it is the inevitable trend for the development of the tissue paper industry to reduce production costs and eliminate backward production. Especially for the medium-sized and small tissue paper companies in operation of low profit, only taking the first to solve the problem of energy consumption for tissue paper machine, the market competitiveness of the enterprises is improved.In this paper, starting from the point of view on the structure and production process of tissue paper machine, combining with the causes and factors that affects energy consumption in press section and dryer section of paper machine, the direction of energy optimization in press section and dryer section is proposed. Then the optimal scheme of energy consumption is obtained. At the same time, based on the optimal scheme of energy consumption, automatic control system of tissue paper machine is designed.
The specific work of this paper can be summarized in several aspects as follows:⑴Analysis on energy consumption of each section in tissue paper machineThrough the analysis of paper machine structure and production process, the energy consumption of each section of paper machine is obtained, and at the same time, it is concluded that the energy consumption of the headbox, forming section and coiling section is fixed in the normal operation of the paper machine. However, the range of energy consumption is large in the press section and dryer section. Besides, both of them have the potential to optimize energy consumption. Finally, the energy optimization of the press section and the dryer section is confirmed as the important content of this paper.⑵Theoretical analysis and optimization of energy consumption in press sectionThrough the analysis of the structure of press section and the theory of pressing dewatering, it is obtained that the paper dryness which has been pressed is used as index of energy consumption in press section. And at the same time, it is confirmed that the nip pressure and the speed of paper machine are the main factors which affects the energy consumption of the press section. Combined with the actual production of paper machine, the data of press dewatering is tested and recorded, the data graph is mapping and the functional relationship between the nip pressure, the speed of the paper machine and the dryness of the paper is fitted. Finally, the best range of nip pressure and the speed of the paper machine are confirmed and optimization of energy consumption in press section is realized.⑶Theoretical analysis and optimization of energy consumption in dryer sectionBased on the drying process of paper and the theory of drying, the dryer section can be divided into steam condensate system, the ventilation system and heat recovery system, and then the characteristics of energy distribution and factors for each system are analyzed. Under the condition of ensuring the stability of the paper sheet, the efficiency of the dryer and the hood, through the controlling of the temperature and humidity of exhaust air in heat recovery system, the capacity of the heat recovery is enhanced and the preheating temperature of fresh air is increased. The consumption of steam that heat the fresh air is saved and the optimization of energy consumption in the dryer section is realized.⑷Design for automatic control system of paper machine based on energy optimization schemeCombined with energy optimization scheme of the press section and dryer section, the control requirements of the paper machine drive control system and DCS (Distributed Control System, DCS) control system are summarized. SIEMENS STEP7 and WinCC7.0 are used as software platform, SIEMENS S7-300PLC (Programmable Logic Controller, PLC) is used as the hardware platform, and industrial Ethernet and Profibus-DP are used as communication mode, then the design of automatic control system for tissue paper machine is completed.Through the analysis of above, the operating parameters in the press section and dryer section of tissue paper machine is controlled reasonably, which is beneficial for saving electrical and thermal energy in the production process of the paper machine. And the energy optimization of the tissue paper machine is realized, cost of production is reduced, the market competitiveness of enterprises is improved.