Research On Control Strategy Of Large-scale Cryogenic Treatment Equipment

Cryogenic treatment is a new type of material treatment technology, it can significantly improve the mechanical properties and service life, and it has been widely used in the equipment manufacturing, processing and other fields. How to get a inexpensive, reliable and controllabled low-temperature environment conveniently and quickly is one of the key technologies of Cryogenic treatment. The mechanical structure manufacturing technology has been quite mature and tended to standardization. Compared with this situation, the research of control strategy and the related algorithm is lagging behind, and can not be well used in the actual equipment. Under this background, this paper is with the large-scale cryogenic treatment equipment for research object. And conducted a research in control strategy and algorithm of temperature measuring accuracy, temperature field uniformity, energy saving control, stability of and accuracy control system. Main completed work as follows:Discussed the development and present research status of cryogenic treatment technology at home and abroad. Analyzed the cryogenic treatment equipment technical status and trends. Analyzed the structure and work principle of SLX-3500R large-scale cryogenic treatment equipment, and discussed the key technology of the control system. Established the cooling capacity control model of SLX-3500R large-scale cryogenic treatment equipment and proposed the concept of'subcooling capacity'in cryogenic treatment. To achieve the target of saving control, designed the'best subcooling capacity control algorithm'and the'the heat transfer efficiency regulation method'. To achieve the target of temperature measuring accuracy, proposed the'Multi-point temperature measurement, Weighted summation'measurement method. To achieve the target of temperature field uniformity, proposed the'Divide temperature area, Multi-point control'control strategy. The improved Smith-PID controller was disposed for every cooling capacity auxiliary adjusting terminal in each temperature area. Designed PID parameters tuning module and model parameters identification module by the principles of Z-N algorithm and Relay recognition. Developed a set of cryogenic processing measure and control system by the technology of LabVIEW and PLC. Realized the control strategy and algorithm which designed by this paper. Analyzed the result of Off-line simulation and Real-time control at last. The result shows that the design of the control system meet the requirements.The research work of this paper is mainly for the liquid nitrogen refrigeration type cryogenic treatment equipment with a super large volume working chamber. The research results of this paper provide a certain reference for relevant technical personnel in cryogenic control technology field.