Stirred vessel reactors

Gas-phase processes commercialized in the late 1960s offer much simpler operation. Since they eliminate solvent, solvent separation, recovery, and purification are unnecessary. Polymerization is carried out in stirred-vessel reactors or in fluidized beds. A very successful fluidized-bed process is Union Carbide s UNIPOL technology444 designed originally for producing HDPE and extended later to LLDPE. Ethylene is polymerized by injecting the fine catalyst powder (organotitanium or... 

The group of Schuth has developed a number of reactors close to conventional testing methods with different degrees of sample integration. For multiphase reactions a 25-fold stirred vessel reactor has been developed [31] and for heterogeneous gas-phase reactions a 16-fold fixed-bed reactor has been presented [32],... 

In Figure 5 the predictions of the second model are compared against the experimental data published in (2) and obtained in a small, well stirred, vessel reactor with 1 It total volume. The various initiators were tested under conditions representative of polymerization in commercial units, that is with 20 60 seconds residence time and an operating pressure between 1278 and 2352 atm. For the sake of convenience we will use here the same nomenclature and dimensions as in (2). The kinetic parameters used were those given in Table I. The relative size of the two small volumes and the recirculation rates were estimated once and for all cases from equations (13) and (15). The other parameter values, determined independently, were not changed in order to obtain a better fit with the data. As can be seen, the imperfectly mixed model is in excellent agreement with the experimental data, and accurately accounts for the effect of initiator type (Figure 5). 

Effective engineering design of the cracking reactor for waste plastic processing is very important since the carbonaceous solid residue is one of the cracking products (levels up to 10% or more) and its continuous removal from the reactor is necessary to ensure profitable running. Stirred vessel reactors which have augers in the bases to facilitate continuous char removal are presented. 

Weng, H.-S. Wang, C.-M. Wang, D.-H., A Preliminary Study on a Continuous Flow Stirred Vessel Reactor for Tri-Liquid-Phase Phase Transfer Catalysis. Ind. Eng. Chem. Res. 1997, 36,3613. 

Scaling up of bubble columns is generally based on the requirement of keeping kiA constant. Since A is proportional to, this imphes keeping the superflcial gas velocity constant. Some design aspects of bubble reactors will be illustrated in an example following the section on stirred vessel reactors. 

The shape of the response curve for an impulse function f t) is shown in Fig. 3.3b for various residence time distribution functions. Figure 3.4c, shows the response curves F t) for a step function. The limiting cases of an ideal stirred vessel and an ideal tubular reactor are shown in both b and c. To quantify RTD curves, two fundamentally different models are used (a) the so-called one-dimensional dispersion model, primarily used for tubular reactors with low backmixing, and (2) the so-called cell model ( tanks in series model ) which was primarily intended for stirred vessel reactors but is of general validity. 

Greaves M, Barigou M. (1988) Estimation of gas hold up and impeller power in a stirred vessel reactor. Fluid Mixing III. Chem. Eng. Symp. Series No. 108, p 235-256. 

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