Monomer plug flow reactor with

In the literature many studies on LDPE tubular reactors are found (2-6).All these studies present models of the tubular reactor, able to predict the influence, on monomer conversion and temperature profiles, of selected variables such as initiator concentration and jacket temperature. With the exception of the models of Mullikin, that is an analog computer model of an idealized plug-flow reactor, and of Schoenemann and Thies, for which insufficient details are given, all the other models developed so far appear to have some limitations either in the basic hypotheses or in the fields of application. 

Table 22.8 compares the performance of the SR process for cleaning a 1 MM SCFD (miUion standard cubic feet per day) (0.0283 x lO m /day) air stream containing 260 ppm vinyl chloride monomer (VCM) to a level of 1 ppm with that of a conventional plug-flow reactor using a standard oxidation catalyst at a reaction temperature of 600 K [18]. The adsorbent in the SR process was RB... 

The monomer feed is converted into Polyamide-6 by polycondensation and polyaddition reactions [930]. This reaction step can be realized by a complex reactor which can be modeled as a sequence of stirred tank and plug-flow reactors. An exemplary model flowsheet comprising two reactors (CSTR) with an intermediate water separation (Split) is shown in Fig. 5.20. Such a model of the reaction section can be analyzed by means of Polymers Plus, an extension of Aspen Plus for handling polymer materials [513]. 

In the case of first-order polymerisation (when it is assumed that the concentration of AC is imchangeable during the process) for the plug flow reactor, the monomer concentration varies in accordance with the following equation [1] ... 

In a PFR (plug flow reactor), the polymer composition can be found by integration of the incremental addition to the polymer across the length of the reactor. During the progression of the monomers in a PFR, the composition varies with conversion ... 

Solution, l ree possibilities are sketched in Fig. 12.4. With a semibatch reactor, the more reactive monomer is replenished as the reaction proceeds to maintain/i (and therefore FJ constant. A method for calculating the appropriate rate of addition has been described. In a continuous stirred tank (backmix) reactor, both fi and Fx are constant with time. In a continuous plug-flow reactor, the variation in Fx can be kept small by limiting the conversion per pass in the reactor. Note that the last two techniques require facilities for separating unreacted monomer from the polymer, and in most cases, recycling it. 

MF = 0.01 g/cc-water because the residence times of both reactors are fixed at 0= 20 minutes. From this theoretical and experimental results, therefore, a plug flow type reactor with a divided monomer feed is recommended for the first stage reactor(pre-reactor), because the volume of the reactor can be decreased by decreasing monomer concentration in a feed stream. Nevertheless, the steady state particle number attained in this reactor can be increased. 

Particles of polypropylene are continuously formed at low pressure in the reactor (1) in the presence of catalyst. Evaporated monomer is partially condensed and recycled. The liquid monomer with fresh propylene is sprayed onto the stirred powder bed to provide evaporative cooling. The powder is passed through a gas-lock system (2) to a second reactor (3). This acts in a similar manner to the first, except that ethylene as well as propylene is fed to the system for impact co-polymer production. The horizontal reactor makes the powder residence time distribution approach that of plug-flow. The stirred bed is well suited to handling some high ethylene co-polymers that may not flow or fluidize well. 

This can be explained by the fact that the flow in the CCTVFR became closer to plug flow as the Taylor number was dropped closer to. Therefore, the steady-state particle number and the steady-state monomer conversion could be arbitrarily varied by simply varying the rotational speed of the inner cylinder. Moreover, no oscillations were observed, and the rotational speed of the inner cylinder could be kept low, so that the possibility of shear-induced coagulation could be decreased. Therefore, a CCTVFR with these characteristics is considered to be highly suitable as a pre-reactor for a continuous emulsion polymerization process. In the case of the continuous emulsion polymerization of VAc carried out with the same CCTVFR, however, the situation was quite different [365]. Oscillations in monomer conversion were observed, and almost no appreciable increase in steady-state monomer conversion occurred even when the rotational speed of the inner cylinder was decreased to a value close to. Why the kinetic behavior with VAc is so different to that with St cannot be explained at present. 

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