Dispersion stirred, CSTR

During the manufacturing process, if the grafting increases during early stages of the reaction, the phase volume will also increase, but the size of the particles will remain constant [146-148]. Furthermore, reactor choice plays a decisive role. If the continuous stirred tank reactor (CSTR) is used, little grafting takes place and the occlusion is poor and, consequently, the rubber efficiency is poor. However, in processes akin to the discontinuous system(e.g., tower/cascade reactors), the dispersed phase contains a large number of big inclusions. 

Based on the kinetic mechanism and using the parameter values, one can analyze the continuous stirred tank reactor (CSTR) as well as the dispersed plug flow reactor (PFR) in which the reaction between ethylene and cyclopentadiene takes place. The steady state mass balance equations maybe expressed by using the usual notation as follows ... 

The physical situation in a fluidized bed reactor is obviously too complicated to be modeled by an ideal plug flow reactor or an ideal stirred tank reactor although, under certain conditions, either of these ideal models may provide a fair representation of the behavior of a fluidized bed reactor. In other cases, the behavior of the system can be characterized as plug flow modified by longitudinal dispersion, and the unidimensional pseudo homogeneous model (Section 12.7.2.1) can be employed to describe the fluidized bed reactor. As an alternative, a cascade of CSTR s (Section 11.1.3.2) may be used to model the fluidized bed reactor. Unfortunately, none of these models provides an adequate representation of reaction behavior in fluidized beds, particularly when there is appreciable bubble formation within the bed. This situation arises mainly because a knowledge of the residence time distribution of the gas in the bed is insuf-... 

In this chapter, we develop the basis for design and performance analysis for a CSTR (continuous stirred-tank reactor). The general features of a CSTR are outlined in Section 2.3.1, and are illustrated schematically in Figure 2.3 for both a single-stage CSTR and a two-stage CSTR. The essential features, as applied to complete dispersion at the microscopic level, i.e., nonsegregated flow, are recapitulated as follows ... 

Pertinent examples of the value of dimensional analysis have been reported in a series of papers by Maa and Hsu (19,37,63). In their first report, they successfully established the scale-up requirements for microspheres produced by an emulsification process in continuously stirred tank reactors (CSTRs) (63). Their initial assumption was that the diameter of the microspheres, <7ms, is a function of phase quantities, physical properties of the dispersion and dispersed phases, and processing equipment parameters ... 

In this chapter some effects of segregation on the kinetics of a chemical reaction between two liquid phases carried out in a continuous stirred tank reactor (CSTR) will be discussed. In the derivations of these effects it will be assumed that during the reaction the dispersed phase is maintained (e.g., in the case of extraction combined with chemical reaction) and that all dispersed drops have the same size. This means that when there is segregation it is only the age distribution which causes a concentration distribution in the dispersed phase. 

Continuous Stirred Tank Reactors. Biesenberger (8) solved for the MWD with condensation polymerization in a CSTR, analogous to the treatment Denbigh (14) provided for the other two mechanisms. In this case, the variable residence time distribution leads to an extremely broad MWD with even the maximum weight fraction at the lowest molecular weight (monomer). The dispersion index approaches infinity as the condensation is driven to completion in a stirred tank reactor. A sequential analytical solution of the algebraic equations was obtained with a numerical evaluation of the consecutive equations. 

Ideal continuously stirred reactor (CSTR) for which a volume element entering the CSTR will become uniform dispersed with all the other volume elements in the reactor. The initial outlet will be equal to the ratio of the tracer volume divided by the reactor volume times the initial tracer concentration, and would then exponential decay in time. 

CRE Chemical Reaction (or Reactor) Engineering CSF Continuous Surface Force CSS Continuous Surface Stress CSTR Continuous Stirred Tank Reactor model DCS Deferred Correction Source DM Dispersion Model... 

In the fixed bed fluid/solid CSTR and BR, the recirculation rate must be increased until the measured rate of reaction stops being dependent on this factor. However, if the solid is dispersed in the fluid of the CSTR or BR, consideration must also be given to the problem of slip, which governs the relative velocity between the suspended solid and the suspending fluid. Does additional stirring increase the relative velocity between solid and fluid or does it simply move both of them more vigorously, with minimal effect on the relative velocity ... 

The nonlinearity of chemical processes received considerable attention in the chemical engineering literature. A large number of articles deal with stand-alone chemical reactors, as for example continuously stirred tank reactor (CSTR), tubular reactor with axial dispersion, and packed-bed reactor. The steady state and dynamic behaviour of these systems includes state multiplicity, isolated solutions, instability, sustained oscillations, and exotic phenomena as strange attractors and chaos. In all cases, the main source of nonlinearity is the positive feedback due to the recycle of heat, coupled with the dependence of the reaction rate versus temperature. 

Residence time distribution studies by these researchers indicated that for a tube packed with 3-mm glass beads, an appropriate n-CSTR model to use involves a number of stirred tanks that is in the high teens. Consequently, the authors concluded that the extent of longitudinal dispersion was relatively small. Indeed, it is not umeasonable to assume that a PFBR model might provide good estimates of the conversion to be expected in packed beds of this type. If a similar packed bed is... 

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