Stirred tank reactor , practical considerations

Continuous-Flow Stirred-Tank Reactor. In a continuous-flow stirred-tank reactor (CSTR), reactants and products are continuously added and withdrawn. In practice, mechanical or hydrauHc agitation is required to achieve uniform composition and temperature, a choice strongly influenced by process considerations, ie, multiple specialty product requirements and mechanical seal pressure limitations. The CSTR is the idealized opposite of the weU-stirred batch and tubular plug-flow reactors. Analysis of selected combinations of these reactor types can be useful in quantitatively evaluating more complex gas-, Hquid-, and soHd-flow behaviors. 

STIRRED TANK REACTOR SOME PRACTICAL CONSIDERATIONS... 

In practice, the continuous mass polymerization is rather complicated. Because of the high viscosity of the copolymerizing mixture, complex machinery is required to handle mixing, heat transfer, melt transport, and devolatilization. In addition, considerable time is required to establish steady-state conditions in both a stirred-tank reactor and a linear-flow reactor. Thus, system start-up and product grade changes produce some off-grade or intermediate grade products. Copolymerization is normally carried out between 100 and 200°C. Solvents are used to reduce viscosity or the conversion is kept to 40-70%, followed by devolatilization to remove solvents and monomers. Devolatilization is carried out from 120 to 260° C... 

Stirred tank reactor Some practical considerations... 

Industrial manufacture of LLDPE, based on slurry polymerization in hexane, in a series of continuous stirred tank reactors using 1-butene as the comonomer is known. Solution polymerization of LLDPE in cyclohexane under elevated temperature and pressure using 1-octene has also been practiced industrially. In all these manufacturing processes, residence time of the reactants in the reactors is an important consideration. 

---