DCS control system in the rectification of the successful application
Vinyl chloride monomer is indispensable for the production of PVC raw materials, at present, most enterprises is the use of calcium carbide was prepared by vinyl chloride monomer. In the process of preparation of vinyl chloride monomer, vinyl chloride is essential to the process of distillation, its heat and mass transfer process is very complex, distillation load requirements often change because of production, resulting in distillation system pressure is highly difficult operation, easily exceeding the purity of monomer, seriously affecting the quality of a large number of resins. Address the above problems, and in order with the implementation of technology projects expansion of vinyl chloride, the company adopted SUPCON JX-300X DCS Control system and corresponding control program, and was put into operation in May 2003 and achieved good results.
1 process Crude vinyl chloride into the whole by the first condenser compressor, to use of industrial water cooling, condensing the crude liquid vinyl chloride. Liquid vinyl chloride into the water separator by potentiometer, and then by continuous density stratification into low-boiling tower. All condenser into the exhaust gas is not cooling the condenser, as reflux liquid return to the top of the low boiling tower. Low boiling kettle heating tower through the bottom of the converter loop hot water heating to the liquid along the plate downstream of low boiling distillation. Bent along the upward flow of air and Tray Tray liquid to heat and mass exchange, and finally by the tower condenser to -10 frozen brine to the cooling tower as a reflux liquid, non-condensing gas condensate from top of the tower by the whole pass into the exhaust gas processing device, a low boiling bottom of the column to remove low boiling through the middle of vinyl chloride with potentiometer slot into the high boiling tower after tower of high boiling heat, the low boiling point distilled vinyl composition, by the product condenser were condensed into the single tank, the high boiling discharged from the bottom of the column of the two valves.
2 the system and the control of program implementation
2.1 System Components Rectification of DCS control system consists of hardware and software systems composed of two parts. Hardware configuration, according to the actual situation, the configuration of the two operating stations, a control station. Operating station selected Advantech P4 IPC By Scne process control networks and controllers to communicate. From the control station Power supply , Master card, data cards and forwarding cards and other hardware input and output composition. In addition, configure the printer 1 set, UPS UPS 1.
Software configuration, JX-300X system includes monitoring software and the configuration software of two parts, the configuration software includes the basic configuration software (SCKey), flow chart production software (SCDraw), report creation software (SCForm), programming Language (SCLang) and so on. The configuration software is very easy to implement various image editing and complex control structure. Monitoring software is mainly used for the operator to operate and history inquiries.
2.2 Control implementation Vinyl chloride distillation process is characterized by the existence of the great physical relevance, and vinyl chloride into the crude distillation system components, flow, temperature changes in the control tower a great impact. In response, through the establishment of multi-variable decoupling control system, the relevant variables as the introduction of feed-forward signal, to eliminate the disturbance, and the lag correlation. According to the above situation, control can be divided into low-boiling distillation tower, high-boiling two parts of the control tower. Low boiling tower control by the end of row pressure control (PIRC-103), Passing control (LIRC101), low-boiling kettle temperature control (TIRC102) and low boiling reflux control tower (TIRC101) 4 loop and low tower temperature, pressure, etc. test dots. Detection of high-boiling tower control tower by the high-boiling liquid level control (LIRC201), high boiling tower reflux control (TIRC201), finished pressure control (PIRC201) 3 loop and the tower section and stripping section of distillation temperature and pressure test points composition. The PIRC-103, TIRC102, TIRC101, TIRC201, PIRC201 by a single loop.
Specific analysis are too low boiling material control tower (LIRC101) and high boiling liquid level control tower
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