Vertical tank reactors

The productivity of algae consortium with respect to changes in pH, temperature, and light penetration depth in raceways, vertical tank reactors, and polybags [83,84],... 

The melted dehydrochlorinated plastic is then sent to a vertical tank pyrolyzer, fitted with a scraper for removing carbonaceons material on the reactor wall. Energy for pyrolysis is fed from a jacket heater and a high-temperatnre gas heater in a circulating fnmace, and blown into the bottom of the reactor, holding the temperature at 420°C. 

Reactors used in ethylene polymerizations range from simple autoclaves and steel piping to continuous stirred tank reactors (CSTR) and vertical fluidized beds. Since the 1990s, a trend has emerged wherein combinations of processes are used with transition metal catalysts. These combinations allow manufacturers to produce polyethylene with bimodal or broadened molecular weight distributions (see section 7.6). 

The stirred-tank reactor consists of a box or tank with a stirrer in it. The solid medium in the tank is stirred in batch or continuous mode to facilitate oxygen mass transfer. Figure 8 shows the rectangular pilot reactor (2 x 0.8 x 2.3 m) designed by Durand and Chereau [70] to culture T. viride with sugar beet pulp as raw material. The thickness of the substrate layer in the reactor is 1 m. Three vertical screws are bound to a conveyor with dual direction movement. The linear movement speed of the conveyor and the rotating rate of the screws are... 

Fig. 7.23. Simulated velocity in a vertical plane of stirred tank 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... 

Figure 8.2 Types of continuous-flow stirred-tank reactors (a) three-stage cascade of stirred-tank reactors (b) vertically staged cascade of three stirred tanks. Compartmented versions of a battery of stirred tanks in a single horizontal shell may also be employed. (Adapted from J. R. Couper, W. R. Penney, J. R. Fair, and S. M. Walas. Chemical Process Equipment Selection and Design. Copyright 2010. Used with permission of Elsevier.)...

Vertical and horizontal capacitive apparatus appointed by mechanical mixers of impeller, turbine, ribbon, disk, extrusion type including stirring rod for high viscosity mediums mixing are referred to stirring reactors or cascade of flow reactors [3-5, 10]. However, application of apparatus with mechanical mixing for polymers synthesis is limited by maximum limit of viscosity 10-10 Pa-sec. Nevertheless, about 90% of plastics and synthetic rubbers, and 70% of fibers are produced in stirred tank reactors [10]. 

The method of suspension receipt by mixing of initial homogeneous reagents in turbulent regime realized by rotary pumps arms is prevalent at conditions of industrial production for carrying out of fast chemical reactions. With the aim of comparison of effectiveness of work of tubular turbulent apparatus and tank reactors (rotary pumps) mechanical mixer of "turnip" type was chosen that woriced by rotary pump principle. In combination with intensive circulating movement in vertical direction (Fig. 5.18) high speed at mixer s end leads I... 

In most exothermic processes carried out in a stirred tank reactor the bulk of the heat of reaction is carried away by external cooling, either via the wall of the reactor, or by means of an internal or extenal heat exchanger. Internal heat exchangers are usually vertical tube bundles or coils (spirals), mounted coaxially with the impeller shaft. When external heat exchangers are used, the reactor contents are pumped through it and back into the reactor. We consider here the CSTR the semi-batch reactor is treated in section 8.4.4. The steady-state heat balance for a first order reactor in a cooled CSTR can be written as follows ... 

ILLUSTRATIVE EXAMPLE 7.5 A vertical tank 1.4 m in diameter and 1.9 m high, contains coolant water for a reactor at a height of 1.5 m. Water flows into the tank through a 9 cm pipe with a velocity of 4 m/s. Water leaves the tank through a 4 cm pipe at a velocity of 3 m/s. Is the level in the tank rising or falling ... 

The oldest example of this procedure is the manufacture of high-impact polypropylene, as already described (see Section 8.1.2). Other applications have become more popular lately, especially for the production of bimodal resins. Figure 8.36 illustrates a tandem process using two gas-phase vertical stirred-tank reactors. Several other reactor combinations are used industrially [65]. For heterogeneous processes, the first reactor(s) in the series can be either slurry or gas-phase, but commonly the second reactor (or set of reactors) is a gas-phase reactor. This is especially important when the production of polymers with lower crystallinity... 

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