Stirred-tank reactors single

Fio. 1.26. Continuous stirred-tank reactor single tank, reactions in series, A - P - Q... 

The polymeric material produced in a single stirred-tank reactor will, except for stochastic variations, be of uniform composition. This polymer composition can be significantly different from the composition in the monomer feed mixture unless the conversion is high. If several tanks are connected in series the composition of the polymer produced in each reactor can be quite different. Since most particles are formed in the first reactor this change in composition in the following reactors can yield polymer particles in which composition varies with radius within the particles. 

Nomura and Fujita (12), Dougherty (13-14), and Storti et al. (12). Space does not permit a review of each of these papers. This paper presents the development of a more extensive model in terms of particle formation mechanism, copolymer kinetic mechanism, applicability to intervals I, II and III, and the capability to simulate batch, semibatch, or continuous stirred tank reactors (CSTR). Our aim has been to combine into a single coherent model the best aspects of previous models together with the coagulative nucleation theory of Feeney et al. (8-9) in order to enhance our understanding of... 

Figure 15.2 Bubble coalescence measured in a stirred tank reactor at 1000 Hz with a single 10-bit monochrome camera (From [8]).

Consider a simple first-order exothermie reaction, A —> B, carried out in a single, constant-volume, continuous stirred-tank reactor (Fig. 3.12), with constant jacket coolant temperature, where r = - k Ca,. 

This analysis is limited, since it is based on a steady-state criterion. The linearisation approach, outlined above, also fails in that its analysis is restricted to variations, which are very close to the steady state. While this provides excellent information on the dynamic stability, it cannot predict the actual trajectory of the reaction, once this departs from the near steady state. A full dynamic analysis is, therefore, best considered in terms of the full dynamic model equations and this is easily effected, using digital simulation. The above case of the single CSTR, with a single exothermic reaction, is covered by the simulation examples, THERMPLOT and THERM. Other simulation examples, covering aspects of stirred-tank reactor stability are COOL, OSCIL, REFRIG and STABIL. 

Continuous Flow Reactors—Stirred Tanks. The continuous flow stirred tank reactor is used extensively in chemical process industries. Both single tanks and batteries of tanks connected in series are used. In many respects the mechanical and heat transfer aspects of these reactors closely resemble the stirred tank batch reactors treated in the previous subsection. However, in the present case, one must also provide for continuous addition of reactants and continuous withdrawal of the product stream. 

If the operating conditions used in that illustration are again employed, determine the volume of a single continuous stirred tank reactor which will give 40% conversion of the butadiene when the liquid flow rate is 0.500 m3/ksec. 

ILLUSTRATION 9.3 QUANTITATIVE DEVELOPMENT OF SERIES REACTION RELATIONSHIPS FOR A SINGLE CONTINUOUS STIRRED TANK REACTOR... 

When reactions 9.3.3 and 9.3.4 take place in a single continuous stirred tank reactor, the route to a quantitative relation describing the product distribution involves writing the design equations for species V and A. 

ILLUSTRATION 10.2 DETERMINATION OF HEAT TRANSFER AND VOLUME REQUIREMENTS FOR SINGLE AND MULTIPLE CONTINUOUS STIRRED TANK REACTORS... 

Thus, for a single continuous stirred tank reactor, the required reactor volume will be... 

The responses of a single ideal stirred tank reactor to ideal step and pulse inputs are shown in Figure 11.4. Note that any change in the reactor inlet stream shows up immediately at the reactor outlet in these systems. This fact is used to advantage in the design of automatic control systems for stirred tank reactors. 

Acylation of aromatic ethers in the presence of a variety of metal chlorides and oxides [52]. The rate enhancement was probably caused by large temperature gradients but was not evaluated quantitatively. Reaction conditions a single-mode stirred tank reactor, fourfold excess of anisole, no solvent. 

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 ... 

The kinetics of a liquid-phase chemical reaction are investigated in a laboratory-scale continuous stirred-tank reactor. The stoichiometric equation for the reaction is A 2P and it is irreversible. The reactor is a single vessel which contains 3.25 x 10 3 m3 of liquid when it is filled just to the level of the outflow. In operation, the contents of the reactor are well stirred and uniform in composition. The concentration of the reactant A in the feed stream is 0.5 kmol/m3. Results of three steady-state runs are ... 

A reaction A + B P, which is first-order with respect to each of the reactants, with a rate constant of 1.5 x 10-5 m3/kmols, is carried out in a single continuous flow stirred-tank reactor. This reaction is accompanied by a side reaction 2B Q, where Q is a waste product, the side reaction being second-order with respect to B, with a rate constant of 11 x 10-5 m3/kmols. 

A single continuous stirred tank reactor is used for these reactions. A and B are mixed in equimolar proportions such that each has the concentration C0 in the combined stream fed at a volumetric flowrate v to the reactor. If the rate constants above are kP = kQ = k and the total conversion of B is 0.95, that is the concentration of B in the outflow is 0.05C0, show that the volume of the reactor will be 69 v/kC0 and that the relative yield of P will be 0.82, as for case a in Figure 1.24, Volume 3. 

A batch reactor and a single continuous stirred-tank reactor are compared in relation to their performance in carrying out the simple liquid phase reaction A + B —> products. The reaction is first order with respect to each of the reactants, that is second order overall. If the initial concentrations of the reactants are equal, show that the volume of the continuous reactor must be 1/(1 — a) times the volume of the batch reactor for the same rate of production from each, where a is the fractional conversion. Assume that there is no change in density associated with the reaction and neglect the shutdown period between batches for the batch reactor. 

In continuous reactor systems, all reactants are continuously fed to the reactor, and the products are continuously withdrawn. Typical continuous reactors are stirred tanks (either single or in cascades) and plug flow tubes. Continuous reactors are characterized by stationary conditions in that both heat generation and composition profiles remain constant during operation (provided that operating conditions remain unchanged ). 

Reaction times of fermentation range from a few hours to several days. Batch processes are common, but continuous stirred tanks also are used either singly or in stages. A continuous stirred tank reactor (CSTR) also is called a chemostat. Figure 8.4 is a schematic of a fermentor with representative dimensions from the literature. 

The system mostly applied in practice for supply of ozone is the bubble column and the stirred tank reactor. With these reactor systems it is always possible to set up the complete reactor modification as a plug flow reactor, a continuous flow single stirred tank reactor or a cascade of stirred tank reactors. 

N. Watanabe, H. Kurimoto, M. Matsubara, and K. Onogi. Periodic control of continuous stirred tank reactor II Case of a nonisothermal single reactor. Chem. Eng. Sci., 37 745-752, 1982. 

The solutions of the nonsteady-state expression, Eq. (164), both for single tanks and chains of tanks have been made by Acton and Lapidus (Al), Mason and Piret (M5, M6), and Standart (S22). Aris and Amundson (A15, A16), Bilous and Amundson (B7), Bilous et al. (B9), and Gilles and Hofmann (G3) have studied the stability, control, and response of a stirred tank reactor. 

Laboratory studies of the rearrangement process began with semi-continuous operation in a single, 200-mL, glass reactor, feeding 1 as a liquid and simultaneous distillation of 2,5-DHF, crotonaldehyde and unreacted 1. Catalyst recovery was performed as needed in a separatory funnel with n-octane as the extraction solvent. Further laboratory development was performed with one or more 1000-mL continuous reactors in series and catalyst recovery used a laboratory-scale, reciprocating-plate, counter-current, continuous extractor (Karr extractor). Final scale-up was to a semiworks plant (capacity ca. 4500 kg/day) using three, stainless steel, continuous stirred tank reactors (CSTR). 

The autoclave reactors used today in the high-pressure polymerization of ethylene are single stirred-tank reactors, cascades of stirred autoclaves, and multi-chamber autoclaves. 

Single stirred-tank reactors were run in the first industrial scale processes to manufacture LDPE. Today they are used only for plants having lower capacities. The design of a single autoclave is shown in Fig. 5.1-6. It consists of a thick-walled forged-, or two-layer shrunk mantle. The ratio of inside length to inner diameter is typically in the range of one to two, and the volume is 1 - 2 m3. 

Figure 17.9. Stirred tank reactors, batch and continuous, (a) With agitator and internal heat transfer surface, batch or continuous, (b) With pumparound mixing and external heat transfer surface, batch or continuous, (c) Three-stage continuous stirred tank reactor battery, (d) Three-stage continuous stirred tank battery in a single shell.

Watanabe, N., Kurimoto, H., Matsubara, M. Onogi, K. 1982 Periodic control of continuous stirred tank reactors. II. Cases of a non-isothermal single reactor. Chem. Engng ScL 37, 745-752. 

---