Design Of Polypropylene Process Control System Based On DeltaV System

Based on existing problem of polypropylene process control such ascomplex system, non-linearity, quick change by time, big lag, compliacate modelbuilding, make detailed design of dosing process control, reaction processcontrol and recover process control for the PP equipments of Sinopec YangZhouusing DeltaV process control system. The totalizer of dosing control is notaccuracy in the old system of Sinopec YangZhou PP equipments, that impact thecontrollable for polymerization reaction. There has some problems such astemperature rising is too slow and inflexion point control is not good because ofthe big lag of reactor temperature in temperature rising process of polymerizationreaction. There also have some problems such as the tuning result for disturb isnot good that make the temperature and pressure are not controllable in keepingtemperature and pressure process. It is not good for reaction process.Based on above problems, Firstly I design hardware control system withredundant and high reliability by DeltaV plant web structure application. That isnessesary for plant safty and effective production.Secondly, design analog input/output and descrete input/output classmodules and PID cascade control modules, Expert PID logics, master PIDcontrol loop selection, PID split control by DeltaV standard function blocks.Automatic dosing program is designed for dosing system to implement onaccuracy in dosing process. Implement fast response and stability in reactingprocess through Expert PID cascade control loop design. There are2phases inreacting process. They are reacting temperature rising phase and reacting keeping pressure and temperature phase. Simulate reactor temperature singlecontrol loop, temperature cascade control loop(reactor temperature mastercontrol loop and jacket temperature slave control loop), Expert PID cascadecontrol loop(reactor temperature master control loop and jacket temperatureslave control loop) and compare these simulation results in the reactingtemperature rising phase. And analyze the response time and overcome disturbby the formulas and formula development for the3type loops. Simulate reactortemperature single control loop, pressure-temperature cascade controlloop(reactor pressure master control loop and jacket temperature slave controlloop), Expert PID cascade control loop(reactor pressure master control loop andjacket temperature slave control loop) and compare these simulation results inthe reacting keeping pressure and temperature phase.Finally, design split control from the output of the jacket temperature slavecontrol for the2cooling water valves. Implement fast response and equality ofjacket cooling water by different positions of the2cooling water valves onjacket cooling water input pipes. Additionally, design the process safty interlockduring whole process to implement on safety production.