Design And Realization Of The Measurement And Control System For DME Synthesis

In 21centry, China faces challenges in energy supply, especially the liquid fuels. as a new kind of fuels, that the synthesis of dimethyl ether from biomss syngas is a very important way to overcome the challenges. Therefore, the process control of the synthesis of dimethyl ether is been studied in this paper, and then give the basics for industrial scale applications.The synthesis process of dimethyl ether demands that the temperature is 280℃and the pressure is from 3MPa to 5 MPa. The reaction is accomplished in two different reactors, one is reaction vessel, and the other one is fixed bed bubble reactor.According to that the same reaction was accomplished in two different reactors, we got two different yield rate, so we can determine which reactor is better for the synthesis of dimethyl ether.Our tasks were provided necessary technological conditions for the synthesis of dimethyl ether, such as temperature, pressure and flow etc.In order to be convenient for development, we chose the core developing platform based on Advantech industrial control computer and cards. The type of the industrial control computer is IPC610BP, and we chose three cards, they are PCL-813B,PCL-727and PCL-730.The three cards were used to collect signals, and control algorithm was run in the industrial control computer.First, the signals of field sensors and transmitters entered the digital display instruments, and then according to the Transducer terminals of the digital display instruments, the field signals were connected to terminal boards of the cards, so the signals entered the industrial computer through the cards.The actuator of the control system included two electromagnetic valves and two electric regulating valves. One electromagnetic valve and one electric regulating valve were in one group, the two groups accomplished the temperature regulating and the pressure regulating.We mainly used the proportion control algorithm and normal PID control algorithm. Frist, we discretized the continuous PID formula, and then wrote relevant computer program. At last, we accomplished the tuning of the system technological parameters and the system testing and commissioning.The main methods of parameter tuning include theoretical calculation method,empirical formula method and try and error method etc. After debugging and adjusting the system, automatical control of system pressure is realized.