Research And Design On Control System Based On PLC For Liduid Ammonina Treatment Equipment

With the increasing standard of living, apparel made of natural fabrics, such as cotton and flax fiber, are more and more popular with the people. Liquid ammonia treatment technology plays an important role in the finishing and processing of the high-grade garments because of the natural and environment friendly features. The research and development of liquid ammonia-treatment equipment is very significant to enforce the international competitiveness of Chinese textile industry chain and promote the industrial upgrading.On the basis of analysis and calculation on the liquid ammonia treatment process, considering flexible amendment and extensibility upon the scale of production and processes adjustment, a hybrid control systems was designed with field-bus, configuration technology and PLC combined. By making full use of these three characteristics in order to complement each others, Concentrate management and distributed control could be achieved.Corresponding control strategies were designed according the analysis of various characteristics of different subsystem. Then under the guide of those strategies, the structure and implementations of the two levels net control system, Ethernet and deviceNet, based on CSl PLC provided by OMRON were studied and designed. PLC program in the control system was designed with modular method, the core subsystem, pressure controlling of adjust-pressure tank, control of ammonia compressor units and so on were realized in this way.Since the process of ammonia being removed by microwave is difficult to establish accurate mathematical model and involves nonlinear, long time delay and parameter time-varying characteristics, 2 independent fuzzy controllers were designed with the temperature difference, the rate of temperature difference of yarn and the pressure difference, the rate of pressure difference of treatment tank as inputs, while the shift of microwave heater as the output. The structure and parameter were modified and optimized with the expert’s knowledge and the experience summarized form field. On the basis of analysis of fuzzy basic theory and its classifications, the designing process of fuzzy control system for liquid ammonia removed by microwave was traversed and described. The query tables of the two independent fuzzy control systems of yarn temperature and treatment tank pressure were worked out with the fuzzy logic tool box provided by MATLAB, and ultimately the fuzzy control strategies stated above were implemented inside the PLC by programmable method.Configuration software, MCGS, was used to simulate those controlling objects in ammonia treatment system in order to debug and validate the PLC program. The result of study shows that control system based on PLC net for the liquid ammonia treatment is necessary and feasible, and the control system incarnates the unification of advancement and practicability.