Cylindrical batch reactors

In chemical laboratories, small flasks and beakers are used for liquid phase reactions. Here, a charge of reactants is added and brought to reaction temperature. The reaction may be held at this condition for a predetermined time before the product is discharged. This batch reactor is characterized by the varying extent of reaction and properties of the reaction mixture with time. In contrast to the flasks are large cylindrical tubes used in the petrochemical industry for the cracking of hydrocarbons. This process is continuous with reactants in the tubes and the products obtained from the exit. The extent of reaction and properties, such as composition and temperature, depend on the position along the tube and does not depend on the time. 

The pyrolysis of the plastics was carried out in a semi-batch reactor which was made of cylindrical stainless steel tube with 80mm in internal diameter and 135mm in height. A schematic diagram of the experimental apparatus is shown in Fig. 1, which includes the main reactor, temperature controller, agitator, condenser and analyzers. 

Figure 2.4. Schematic drawings of a cylindrical flow reactor and a batch reactor. In the ideal case the flow reactor operates as a plug-flow reactor in which the gas moves as a piston down through the tube, whereas the ideal batch reactor is a well-mixed Tank Reactor...

The interpretation of cA(t) comes from the realization that each cylindrical shell passes through the vessel as an independent batch. Thus, cA(/) is obtained by integration of the material balance for a batch reactor (BR). Accordingly, we may rewrite equation 16.2-11, in terms of either cA(x) or fA(x), as... 

The performance of a reactor for a gas-solid reaction (A(g) + bB(s) -> products) is to be analyzed based on the following model solids in BMF, uniform gas composition, and no overhead loss of solid as a result of entrainment. Calculate the fractional conversion of B (fB) based on the following information and assumptions T = 800 K, pA = 2 bar the particles are cylindrical with a radius of 0.5 mm from a batch-reactor study, the time for 100% conversion of 2-mm particles is 40 min at 600 K and pA = 1 bar. Compare results for /b assuming (a) gas-film (mass-transfer) control (b) surface-reaction control and (c) ash-layer diffusion control. The solid flow rate is 1000 kg min-1, and the solid holdup (WB) in the reactor is 20,000 kg. Assume also that the SCM is valid, and the surface reaction is first-order with respect to A. 

The conversion concept of Rogers PBC system was overfired, updraft, fixed horizontal grate, and cylindrical batch reactor (see Figure 1). 

They used a vertical cylindrical pot furnace of batch type, like Rogers. Two conversion concepts were simulated (a) overfired, updraft, fixed horizontal grate, and batch reactor and (b) underfired, updraft, fixed horizontal grate, and batch reactor. The diameter was 178 mm and primary air was supplied under the grate (Figure 7). A mirror was placed above the overbed section to be able to observe the combustion behaviour. 

The experiments were carried out in the commonly used cylindrical vertical pot furnace (Figure 8). The conversion concept was overfired, updraft, fixed horizontal grate, and batch reactor. The furnace dimensions were 250 mm i.d. and 300 mm in height. The furnace was constructed in two sections, here called conversion system and combustion chamber. This was one simple solution to be able to weigh the mass loss of the packed bed. 

Gort applied a typical pot reactor with vertical cylindrical shape. The conversion concept of Gort s conversion reactor was updraft, over-fired, fixed horizontal grate, and batch reactor. The reactor casing had a inner diameter of 0.3 m and a height of 0.8 m. The design of Gort s pot furnace is very similar to Koistinen et al s. 

The over-fired updraft conversion system has a vertical cylindrical (Figure 11 A) design with an inner diameter of 0.2 m and a height of 0.45 m. The under-fired downdraft batch reactor has a rectangular cross section with the dimensions 0.52x0.48 m and a height of 0.7 m. 

Lichtin and Avudaithai (1996) compared the photocatalytic oxidation of methanol in both aqueous and gas phases. Photocatalytic efficiencies for the two phases were analyzed. Differences in the chemistry of photocatalytic oxidation for the two phases were also studied. Batch reactors were used for both aqueous- and gas-phase reactions. The reactor was a 450-mL, magnetically stirred, cylindrical vessel with an axially aligned 6-W fluorescent lamp emitting light at 360 nm. 02 was bubbled into the reactor at 35 mL/min. Samples were irradiated for 140 min, and product concentrations were determined using gas chromatography. 

Numerous reactions are performed by feeding the reactants continuously to cylindrical tubes, either empty or packed with catalyst, with a length which is 10 to 1000 times larger than the diameter. The mixture of unconverted reactants and reaction products is continuously withdrawn at the reactor exit. Hence, constant concentration profiles of reactants and products, as well as a temperature profile are established between the inlet and the outlet of the tubular reactor, see Fig. 7.1. This requires, in contrast to the batch reactor, the application of the law of conservation of mass over an infinitesimal volume element, dV, of the reactor. In contrast to a batch reactor the existence of a temperature profile does not allow us to consider the mass balances for the reacting components and the energy balance separately. Such a separation can only be performed for isothermal tubular reactors. 

Chemical reactors basically come in the form of tanks, such as for batch reactors or back-mix flow reactors, large cylinders, such as for fluidized-bed or plug-flow reactors, or multiple tubes inside a cylindrical container, such as for plug-flow reactors when special needs exist for temperature control. High pressure and extremes of temperature as well as corrosive action of the materials involved can introduce complications in the design which must be handled by the design engineer. 

In addition to the CSTR and batch reactors, another type of reactor commonly used in industry is the tubular reactor. It consists of a cylindrical pipe and is normally operated at steady state, as is the CSTR. For the purposes of the material presented here, we consider systems in which the flow is highly turbulent and the flow field may be modeled by that of plug flow. That is, there is no radial variation in concentration and the reactor is referred to as a plug-flow reactor (PFR). (The laminar flow reactor is discussed in Chapter 13.)... 

P3-18b Consider a cylindrical batch reactor that has one end fitted with a ftictionless piston attached to a spring (Figure P3-18). The reaction... 

We also discussed the choice of the reactor. A batch reactor has a much larger volume per unit of reaction product and tank like pressure vessels are much more expensive than cylindrical vessels. This combined with the difficulties of handling catalyst slurries and above all of preventing losses of the often rather expensive catalysts made us consider continuously operating reactors with fixed catalyst beds too. We eventually chose for the packed bubble column as a well suited reactor. 

Batch reactors are nsnally cylindrical tanks and the orientation of such tanks is nsnally vertical. Cylindrical vessels are employed becanse they are easier to fabricate and clean than other geometries and becanse the construction costs for high-pressnre nnits are considerably less than for alternative confignrations. For simple stirred vertical batch reactors, the depth of liqnid is nsnally comparable to the diameter of the reactor. For greater liqnid height/diameter ratios, more complex agitation eqnipment is necessary. Agitation can be supplied by stirrer blades of various shapes or by forced circulation with an external or built-in pump. Where more gas-liquid interfacial area is required for evaporation or gas absorption, or where it is necessary... 

The component balance for a commercial-sized circular, cylindrical batch reactor reduces to... 

Batch fermentations are usually subject to substrate and product inhibitions, yielding low hydrogen gas productivities. Hence, typical batch reactors are cylindrical (Katsuda et al., 2000) and flat-plate solar bioreactors (Evens, Chapman, Robbins, D Asaro, 2000 Lehr Posten, 2009) to control hght penetration and, thus, improving H2 conversion. 

Figure 6.17.11 shows experimental results of the epimerization at three different temperatures for a small particle size (0.5-1 mm), which represent the intrinsic kinetics, and for the original 6 x 6 mm cylindrical catalyst pellets, where pore diffusion limitations lead to a decrease of the effective reaction rate. The experiments were conducted in the well-mixed batch reactor. As expected, the influence of mass transfer increases with increasing temperature and becomes strong at 200°C. Note that for clarity Figure 6.17.11 only shows the change of menthol concentration and not of the other two stereoisomers (as in Figure 6.17.5). In addition, note that the initial menthol concentration is not zero as an industrially relevant feed was used. The dashed and solid lines in Figure 6.17.11 represent the results of the calculation by the method described before, showing a good agreement with the experimental data.

Such deviation of the reaction progress from the course described by the collision term developed by [1] can be observed if particle counting devices are used to follow the reaction. Figure 7 (after [7]) describes such reactions in stirred cylindrical batch reactors where for identical stirrer speed the reaction progress should be the same in all systems. The observed reaction progress, however, is different in each system. One would conclude that the so-called turbine-type stirrer is the most effective in generating a reaction-favorable environment, while the... 

Because hydrolytic reactions are reversible, they are seldom carried out in batch wise processes [26,28,36,70]. The reactor is usually a double jacket cylindrical flask fitted with a reflux condenser, magnetic stirrer, and thermometer connected with an ultrathermostat. The catalyst is added to the reaction mixture when the desired temperature has been reached [71,72]. A nitrogen atmosphere is used when the reactants are sensitive to atmospheric oxygen [36]. Dynamic methods require more complicated, but they have been widely used in preparative work as well as in kinetic studies of hydrolysis [72-74]. The reaction usually consists of a column packed with a layer of the resin and carrying a continuous flow of the reaction mixture. The equilibrium can... 

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