(255cc) Online Monitor and Control of the Real-Time Composition of Ternary Gas Mixture in Batch Reactor By Three Cascade Flow Meters during Propene Polymerization

Abstract: The batch polymerization of propene is still widely applied in many industrial practice for production of polypropylene resins. However, since different monomers present different reactivities, composition drifting will take place in the copolymerization process, which in turn affects the properties of the copolymer products. Therefore, how to monitor and control the composition of monomers in batch reactor is of great significance.

In current work, we have developed a method for online monitoring and controlling the real-time composition of ternary gas mixture in batch reactor by three flow meters, a differential pressure volumetric flow meter, a thermal mass flow meter, and a Coriolis mass flowmeter in series.

We applied this technology to ternary copolymerization of ethylene/propene/1-butene and binary copolymerization of propene/1-butene with little H₂ as the chain transfer agent in a gas-phase batch reactor. We found that this technology could reliably monitor and control the real-time composition of ternary gas mixture in reactors as well as conveniently measure the consumption rates of different monomers, which enabled us to easily obtain some basic kinetic parameters such as chain propagation rate constants, reactivity ratios and so on.

Key words: propene batch copolymerization; composition monitoring and controlling; polymer kinetics