| With the development of our country's pharmaceutical industry, 7ACA as the most important pharmaceutical intermediates, which can be used to produce more than 300 kinds of downstream antibiotics products, have become the direction of development of domestic pharmaceutical enterprises. The production of 7ACA needs a chemical cleavage reaction, temperature from -75℃ to 45℃. The chemical reaction is very complex and will last 12 hours. The original LuKang Group adopted artificial liquid nitrogen to cool down the temperature and control the accuracy, which consumed high energy. As a national giant pharmacy enterprise, it is very necessary for LuKang Group to design an Automatic Control System of chiller to control drug quality and reduce energy consumption.The construction of chiller is a dual set. The refrigeration system is composed of high-temperature side R22 and low-temperature side R13, and refrigerant R11 is delivered to the reaction sites by the Process Piping .The chiller automatic control system has complex structure, in order to meet 7ACA production complex chemical reaction process, precise control is needed in the various stages of the cold supply and appropriate pressure, flow, temperature, liquid level and time parameters. As designing this control system, we decided to ensure the stability for the process needs. We select PROFIBUS-DP as the base of the control system. The main station is composed of S7-300 CPU 315-2DP and Siemens touch screen TP270. CPU315 core deals with various data and flow of technique. TP270 can be achievable and convenient for the operator to operate and control. The secondary station uses ET200M and Frequency Control System MICROMASTER440, immediate response to orders issued by the main station and instrumentation and control meters unit to form a complete chiller network control system.PLC of chiller Control System used STEP7-300. We not only use the STEP7 software to program PLC but also use the construct scheme to design this control system. After programming, the PLC SIM software is used to adjust and examine the control units. Take PROFIBUS interface characteristics into account, we choose SPC3 as interface chip to program.As 7ACA chemical reaction time is very long, the process is complex, the load is easy for a drastic change, Refrigerant evaporation and heat transfer process is non -linear, it's difficult to set a mathematical model. In order to achieve the conversion of Mixed State and Single State between heat and cool, and ensure the flow of the system R11. We use fuzzy control technology to achieve R11 flow requirements. 7ACA syntheses in working conditions changes ranges. There is a greater need to adapt to the changes in various parameters. In the process, constantly measuring the input and the state, or output parameters is needed. It is difficult for the electronic expansion valve in accordance with the general feedback control to turn the PID parameters. We use adaptive control system to control the electronic expansion valve.When the control system design and installation is completed, we conducted a careful debugging process from single units with the technology to test system and sum up a lot of experience. Phase based on the principle of combining theory with practice, analysis the problems of the control system in practical use, improve my own ability to solve practical technical problems, and enhance the independence of the project design and debugging capabilities. |
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