Stirred-tank reactors in series

The emulsion process can be modified for the continuous production of latex. One such process (68) uses two stirred-tank reactors in series, followed by insulated hold-tanks. During continuous operation, 60% of the monomers are continuously charged to the first reactor with the remainder going into the second reactor. Surfactant is added only to the first reactor. The residence time is 2.5 h for the first reactor where the temperature is maintained at 65°C for 92% conversion. The second reactor is held at 68°C for a residence time of 2 h and conversion of 95%. 

In the slurry process, the hydrolysis is accompHshed using two stirred-tank reactors in series (266). Solutions of poly(vinyl acetate) and catalyst are continuously added to the first reactor, where 90% of the conversion occur, and then transferred to the second reactor to reach hiU conversion. Alkyl acetate and alcohols are continuously distilled off in order to drive the equiUbrium of the reaction. The resulting poly(vinyl alcohol) particles tend to be very fine, resulting in a dusty product. The process has been modified to yield a less dusty product through process changes (267,268) and the use of additives (269). Partially hydroly2ed products having a narrow hydrolysis distribution cannot be prepared by this method. 

Example 4.5 Derive the state space representation of two continuous flow stirred-tank reactors in series (CSTR-in-series). Chemical reaction is first order in both reactors. The reactor volumes are fixed, but the volumetric flow rate and inlet concentration are functions of time. 

The decomposition reaction A -> B + C occurs in the liquid phase. It has been suggested that your company produce C from a stream containing equimolar concentrations of A and B by using two continuous stirred tank reactors in series. Both reactors have the same volume. The reaction is first-order with respect to A and zero-order with respect to B and C. Each reactor... 

ILLUSTRATION 11.3 USE OF EXPERIMENTAL RESPONSE DATA TO DETERMINE THE NUMBER OF STIRRED TANK REACTORS IN SERIES... 

Use the data of Illustration 11.1 for the response of a reactor network to a pulse input to determine the number of identical stirred tank reactors in series that gives a reasonable fit of the experimental data. Use both the slope and variance methods described above. 

Stirred-tank reactors in series Fig. 3.1 Stirred-tank reactor configurations. 

Consider a system of N continuous flow stirred tank reactors in series as shown in Figure 5-24. Although the concentration is uniform from one tank to another, there is a change in concentration as the fluid traverses between the CFSTRs. This is illustrated in Figure 5-25. The drop in concentration implies that the larger the number of CFSTRs in series, the closer the system would behave as plug flow. 

Continuous emulsion polymerization processes are industrially important for the large-scale production of synthetic polymer latexes, and have been used particularly where the solid polymer is to be recovered by coagulating the polymer latex. St-Bu rubber latex was one of the earliest latex products manufactured using continuous emulsion polymerization processes consisting of a number of stirred-tank reactors in series (CSTRs). Since the 1940s, continuous emulsion polymerization processes have been developed for a variety of products and with different reactor configurations [328]. This is because these continuous reactor systems have several advantages, such as [329] ... 

Graphical methods can be used to obtain the conversion from a series of reactors and have the advantage of displaying the concentration in each reactor. Moreover, no additional complications are introduced when the rate equation is not first order. As an illustration of the procedure consider three stirred-tank reactors in series, each with a different volume, operating as shown in Fig. 4-13<7. The density is constant, so that at steady state the volumetric flow rate to each reactor is the same. The flow rate and reactant concentration of the feed Q and Cq) are known, as are the volumes of each reactor. We construct a graph of the rate of reaction r vs reactant composition. The curved line in Fig. 4- 3b shows how the rate varies with C according to the rate equation, which may be of any order. 

Fig. 4-13 (a) Steady operation of three stirred-tank reactors in series,... 

In the previous example increasing the number of stirred-tank reactors from one to two (with the same total residence time) caused an increase in conversion from 61.2% to 68.8%. Further increase in number of tank reactors in series would lead to a maximum conversion of 79.4%, the value for a tubular-flow reactor with the same residence time. Thus an infinite number of stirred-tank reactors in series is equivalent to a tubular-flow reactor, provided the total residence time is the same. This may be... 

The first-order irreversible exothermic reaction A —> B occurs in the liquid phase of one or more stirred-tank reactors in series. In a series configuration all reactors have the same volume and operate at the same specified temperature. A height- to-diameter ratio of 2 is assumed in the design. The reaction rate is... 

When a much larger reactor volume would be needed to go from batch to continuous operation, the required reactor volume can be considerably reduced by using two or more stirred-tank reactors in series. Much of the... 

ILLUSTRATION 11.3 Use of Experimental Response Data to Determine the Number of Stirred-Tank Reactors in Series... 

Stoichiometry - Conversions Using Balanced Equations http //www.youtube.com/watch v=wySZDEbqbnM Two Continuous Stirred Tank Reactors in Series http //www.youtube.com/watch v=7RLQ9sHkdkk Balances on Multiple Units with Reaction https //www.youtube.com/watch v=tQyrSvll nc Extent of Reaction for Material Balances https //www.youtube.com/watch v=YusSUOjlOUk Three Methods for Solving Reactive Material Balances https //www.youtube.com/watch v=MSzTIRAv5io... 

Other models to characterize residence time distributions are based on fitting the measured distribution to models for a plug flow with axial dispersion or for series of continuously ideally stirred tank reactors in series. For the first model the Peclet number is the characteristic parameter, for the second model the number of ideally stirred tank reactors needed to fit the residence time distribution typifies the distribution. However, these models should be used with care because they assume a standard distribution in residence times. Most distributions in extruders show a distinct scewness, which could lead to erroneous results at very short and very long residence times. The only exception is the co-kneader the high amount of back mixing in this type of machine leads to a nearly perfect normal distribution. 

Emulsion ABS resins produced in continuous stirred-tank reactors in series, are compared in performance with a standard polymer prepared in a conventional batch reactor. Polymer specifications are best met by using a 2-stage CSTR with interstage feed of the faster reacting monomer. 

A flow diagram of the traditional polypropylene suspension ( slurry ) process is shown in Figure 3.13. Propylene, diluent (Cg to saturated hydrocarbons), hydrogen, a catalyst and a cocatalyst are continuously fed to the polymerisation section, which normally consists of one or more stirred tank reactors in series. Polymerisation is carried out at 60 - 80 °C and at pressures below 2 MPa. The polymerised polypropylene forms small powder particles suspended in the diluent. A small amount of atactic polypropylene is formed as a by-product in the polymerisation step and is partly dissolved in the diluent. The slurry is continuously withdrawn from the last reactor after which unreacted propylene is removed from the slurry and recycled to the reactor. 

Reactor type Continuously stirred tank reactors in series... 

Reactor type and size Continuously stirred tank reactors in series, 10 - 100 Continuously stirred tank reactors in series or batch reactors, 10 -100 m Batch or continuously stirred tank reactors in series, 10 - 50 m ... 

Chemical Market Resources [45] has reported that the Dowlex process consists of two stirred tank reactors in series with an isoparaffin (mixture of Cg and C ) solvent operating at 160°C and approximately 320... 

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