(100a) Controllability Study of Gas-Expanded Liquid Phase Ethylene Oxide Plant Via Dynamic Simulation | AIChE

(100a) Controllability Study of Gas-Expanded Liquid Phase Ethylene Oxide Plant Via Dynamic Simulation

Authors 

Xu, Q., Lamar University
Abou Shama, M. A., Lamar University
The direct oxidation of ethylene method is widely used as an industrial synthesis of the ethylene oxide (C2H4O). The conventional way to produce C2H4O is through an epoxidation reaction where ethylene is epoxidized to C2H4O using oxygen as an oxidant, However, this process is considered as one of the most hazardous chemical operating plants due to the presence of very flammable gas like C2H4O and oxygen in high pressure and temperature reactor. Also, about 3.4 million tons of carbon dioxide (CO2) is generated through this process every year. An alternative synthesis to produce C2H4O in the gas-expanded liquid phase by methyltrioxorhenium (MTO) catalyst will dispel those concerns. Unlike the conventional gas epoxidation reaction with oxygen, this reaction takes place in the (ethylene) gas-expanded liquid solvent phase (methanol) while the reaction oxidant is hydrogen peroxide, this process will generate zero CO2 emission and it is safer and more secure than the old conventional gas-phase process.
Abou Shama and Xu (2018) has improved and optimized this gas-expanded liquid phase process via plant-wide steady-state simulation, however, this work still stays at the very early design stage with just PFD (process flow diagram), since the dynamic safety, controllability, and operational flexibility of the process still need to be concerned. To further move on this process design, a plant-wide dynamic simulation is employed to update the P&ID (piping and instrumentation diagram) for this process. The object of this work will develop a control strategy that can reject 10% feed flowrate disturbances and 10% setpoint changes for this process. Also, the controllers must reject all disturbances within 5% deviation of their setpoint. The final design enrolls cascade and ratio control, besides, new pumps, heat exchangers, and buffer drums are added to respond to flowrate disturbances and utility shortage, which has made the gas-expanded liquid phase ethylene oxide process be more close to real industrial production.

Abou Shama, M.A., Xu, Q., 2018. Optimal Design of Gas-Expanded Liquid Ethylene Oxide Production with Zero Carbon Dioxide Byproduct. Industrial & Engineering Chemistry Research 57, 5351-5358.