Stirred tank experiments

The styrene conversion for the continuous flow stirred tank experiments was determined utilizing the concentration of the polymer in the feed and the number average degrees of polymerization... 

Arve and Liapis [34] suggest estimating the parameters characterizing the intraparticle diffusion and the adsorption-desorption step mechanisms of affinity chromatography from the experimental data obtained in a batch system. The numerical simulations of the chromatographic process will use the values of the parameters of the adsorption isotherm and those of the effective pore diffusion as determined from stirred tank experiments together with the film mass transfer coefficients calculated from chemical engineering expressions found in the literature. 

Horstmann and Chase [35] have used the mass transfer parameters determined in stirred tank experiments to simulate the breakthrough curves of affinity chromatography experiments. Numerical methods using different computer packages were carried out to solve the differential equations of the stirred tank adsorption and to predict the performances of a packed bed chromatographic column. 

As illustrated in Fig. i+, a catalyst will reach Tg/yj when the effectiveness for metal removal has dropped to 0.5 In Fig. U we have plotted the values of rim at Tgyyj for various catalysts and tests conditions as a function of experimentally estimated Tg from the desulfurization performance. On the basis of these observations we used rim = 0.5 as a new definition of TgAp simulated stirred-tank experiments the following expression can then be derived, which allows us to calculate for desulfurization,... 

Various experimental methods to evaluate the kinetics of flow processes existed even in the last centuty. They developed gradually with the expansion of the petrochemical industry. In the 1940s, conversion versus residence time measurement in tubular reactors was the basic tool for rate evaluations. In the 1950s, differential reactor experiments became popular. Only in the 1960s did the use of Continuous-flow Stirred Tank Reactors (CSTRs) start to spread for kinetic studies. A large variety of CSTRs was used to study heterogeneous (contact) catalytic reactions. These included spinning basket CSTRs as well as many kinds of fixed bed reactors with external or internal recycle pumps (Jankowski 1978, Berty 1984.)... 

Guichardon etal. (1994) studied the energy dissipation in liquid-solid suspensions and did not observe any effect of the particles on micromixing for solids concentrations up to 5 per cent. Precipitation experiments in research are often carried out at solids concentrations in the range from 0.1 to 5 per cent. Therefore, the stirred tank can then be modelled as a single-phase isothermal system, i.e. only the hydrodynamics of the reactor are simulated. At higher slurry densities, however, the interaction of the solids with the flow must be taken into account. 

Perfectly mixed stirred tank reactors have no spatial variations in composition or physical properties within the reactor or in the exit from it. Everything inside the system is uniform except at the very entrance. Molecules experience a step change in environment immediately upon entering. A perfectly mixed CSTR has only two environments one at the inlet and one inside the reactor and at the outlet. These environments are specifled by a set of compositions and operating conditions that have only two values either bi ,..., Ti or Uout, bout, , Pout, Tout- When the reactor is at a steady state, the inlet and outlet properties are related by algebraic equations. The piston flow reactors and real flow reactors show a more gradual change from inlet to outlet, and the inlet and outlet properties are related by differential equations. 

An nth-order reaction is run in a continuous stirred-tank reactor. The model and program are written in both dimensional and dimensionless forms. This example provides experience in the use of dimensionless equations. 

Drawing heavily from prior experience in hydrogenation of nitriles (7-10) and of ADN to ACN and/or HMD (11), in particular, we decided to restrict the scope of this investigation to Raney Ni 2400 and Raney Co 2724 catalysts. The hydrogenation reactions were initially carried out in a semi-batch reactor, followed by continuous stirred tank reactor to study the activity, selectivity, and life of the catalyst. 

Enzymatic degradation was tested with commercial LAC from M. thermophila (2,000 U L ). E2 and EE2 were completely degraded even in the absence of mediators after 3 and 5 h, respectively, and after 1 h in the presence of some mediators. For El total removal was achieved in 8 h in the presence of VA and >70% for the other mediators after 24 h, whereas elimination reached 65% in the absence of mediators [8]. The immobilization of this enzyme by encapsulation in a sol-gel matrix [58] was employed for the treatment of a mixture of El, E2, and EE2 both in a batch stirred tank reactor (BSTR) operating in cycles and a continuous PBR. Removal of estrogens was >85% in the BSTR and 55%, 75%, and 60% for El, E2, and EE2, respectively, in the PBR. Both systems were able to reduce the estrogenic activity of the mixture in 63%. Likewise, the immobilization of VP in the form of CLEAs completely removed E2 and EE2 within 10 min from batch experiments, with a concomitant reduction of estrogenic activity, higher than 60% for both compounds [44]. 

Stimulus-response experiments were used to evaluate the operation of a 1.465L laboratory stirred-tank reactor as a CSTR. The response curves were obtained (a) by using acetic acid (A, ca = 0.85 mol L-1) as a tracer chasing water in step-change experiments, and (b) by using a small pulse of glacial acetic acid (density = 1.05 g cm-3, M = 60 g mol-1) on a... 

The accompanying table gives values of trace height at various times as read from a recorder for a pulse-tracer experiment (Thurier, 1977). In this experiment 1.5 cm3 of N2 was injected into a stream of He flowing steadily at 150 cm 3 s-1 through a stirred-tank reactor of volume 605 cm3. A thermal conductivity detector was used to compare the outlet stream (N2 + He) with the He feed stream, and the output fiom this as a trace on a recorder is a measure of the concentration of N2 in the outlet stream. 

The main features of the copper catalyzed autoxidation of ascorbic acid were summarized in detail in Section III. Recently, Strizhak and coworkers demonstrated that in a continuously stirred tank reactor (CSTR) as well as in a batch reactor, the reaction shows various non-linear phenomena, such as bi-stability, oscillations and stochastic resonance (161). The results from the batch experiments can be suitably illustrated with a two-dimensional parameter diagram shown in Pig. 5. 

CSTRPULSE - Continuous Stirred-Tank Cascade Tracer Experiment System... 

A system of N continuous stirred-tank reactors is used to carry out a first-order isothermal reaction. A simulated pulse tracer experiment can be made on the reactor system, and the results can be used to evaluate the steady state conversion from the residence time distribution function (E-curve). A comparison can be made between reactor performance and that calculated from the simulated tracer data. 

Experiment with the influence of recycle flow rate and show by simulation that the model has the limits of a well-stirred tank and a plug flow reactor. 

Isothermal Reactor with Complex Reaction 265 Continuous Stirred-Tanks, Tracer Experiment 273 Deactivating Catalyst in a CSTR 268 Distribution of an Insecticide in an Aquatic Ecosystem 581... 

Fig. 5.2.2. Continuous stirred tank reactors experiment (different test periods A and B). Reactor fed with sludge spiked with C12-LAS, the concentration of which in the influent (filled symbols) was increased approximately from 100 to 268mgLT1 the effluent concentration (empty diamonds). (Figure taken from Ref. [47].)...

The types of equipment used, which range from stirred tanks and mixer-settlers to centrifugal contactors and various types of columns, affect both capital and operating costs [9]. In the decision to build a plant, the choice of the most suitable contactor for the specific situation is most important. In some systems, because of the chemistry and mass transfer rates involved, several alternative designs of contacting equipment are available. In the selection of a contactor, one must consider the capacity and stage requirements solvent type and residence time phase flow ratio physical properties direction of mass transfer phase dispersion and coalescence holdup kinetics equilibrium presence of solids overall performance and maintenance as a function of contactor complexity. This may appear very complicated, but with some experience, the choice is relatively simple. 

Attempts have been made to expand the technique to include the analysis of soil biotransformations f23.29V While the hydrodynamic nature and physical structure of soil systems vary widely and are difficult to establish with certainty, two limiting conditions may be specified. The first is where the soil particles are suspended and all phases are well-mixed. This case is not typically found in nature, but is found in various types of engineered soil-slurry reactors. The reactors currently used in our systems experiments include continuous stirred tank reactors (CSTRs) operated to minimize soil washout. 

A glass stirred tank crystallizer with 350 ml volume was used, which had a marine type propeller located near the bottom. The rotational speed was 200 rpm throughout the experiments. The crystallizer had a filter at the center of the bottom to quickly separate the solution... 

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