Reactors static mixers

Five different types of reactors, including tube reactors, static mixers and a microstructured reactor, were tested for the synthesis of an intermediate to 3deld a quinolone antibiotic drug, named Gemifloxacin (FACTIVE ) [13,14]. 

Figure 7.4c shows an in-line static mixer. Dispersion is usually promoted by repeatedly changing the direction of flow locally within the mixing device as the liquids are pumped through. This will give a good approximation to plug-flow in both phases in cocurrent flow. As with gas-liquid reactors, static mixers are particularly suitable when a short residence time is required. 

Bubble column bioreactors, 1 740-742 Bubble column reactors, static mixers in, 15 708-709... 

Tubular reactors are also used to carry out some multiphase reactions. Wamecke et al. (1999) reported use of a computational flow model to simulate an industrial tubular reactor carrying out a gas-liquid reaction (propylene oxide manufacturing process). In this process, liquid is a dispersed phase and gas is a continuous phase. The two-fluid model discussed earlier may be used to carry out simulations of gas-liquid flow through a tubular reactor. Warnecke et al. (1999) applied such a model to evaluate the influence of bends etc. on flow distribution and reactor performance. The model may be used to evolve better reactor configurations. In many tubular reactors, static mixers are employed to enhance mixing and other transport processes. Computational flow models can also make significant contributions to understanding the role of static mixers and for their optimization. Visser et al. (1999) reported CFD... 

Spinning disk reactor Static mixer reactor Monolithic reactors Microreactors HEX reactors... 

Bubble column, packed bubble column, sectionalized bubble column, plate column, external- and internal-loop air-lift reactors, static mixer, venturi scrubbers... 

Technologies Reactors spinning disk reactor, static mixer reactor, microreactors, heat exchange reactors, monolithic reactors, oscillatory flow reactors, trickle bed reactors... 

Wetox uses a single-reactor vessel that is baffled to simulate multiple stages. The design allows for higher destmction efficiency at lower power input and reduced temperature. Its commercial use has been limited to one faciHty in Canada for treatment of a complex industrial waste stream. Kenox Corp. (North York, Ontario, Canada) has developed a wet oxidation reactor design (28). The system operates at 4.1—4.7 MPa (600 to 680 psi) with air, using a static mixer to achieve good dispersion of Hquid and air bubbles. 

Air is compressed to modest pressures, typically 100 to 200 kPa ( 15-30 psig) with either a centrifugal or radial compressor, and mixed with superheated vaporized butane. Static mixers are normally employed to ensure good mixing. Butane concentrations are often limited to less than 1.7 mol 1 to stay below the lower flammable limit of butane (144). Operation of the reactor at butane concentrations below the flammable limit does not eliminate the requirement for combustion venting, and consequendy most processes use mpture disks on both the inlet and exit reactor heads. A dow diagram of the Huntsman fixed-bed maleic anhydride process is shown in Figure 1. 

In the adiabatic process, the reactants are mixed rapidly ia a smaH-volume, high throughput static mixer without cooling (65). The hot product is used direcdy. A 250-mL reactor of this type can produce 8 t/d of peroxomonosulfuric acid. 

Reaction Conditions. Typical iadustrial practice of this reaction involves mixing vapor-phase propylene and vapor-phase chlorine in a static mixer, foEowed immediately by passing the admixed reactants into a reactor vessel that operates at 69—240 kPa (10—35 psig) and permits virtual complete chlorine conversion, which requires 1—4 s residence time. The overaE reactions are aE highly exothermic and as the reaction proceeds, usuaEy adiabaticaEy, the temperature rises. OptimaEy, the reaction temperature should not exceed 510°C since, above this temperature, pyrolysis of the chlorinated hydrocarbons results in decreased yield and excessive coke formation (27). 

When it is deleterious, laminar flow can be avoided by mixing over the cross section. For this purpose static mixers in line can be provided. For very viscous materi s and pastes, screws of the type used for pumping and extrusion are used as reactors. 

Bubble Reactors In bubble columns the gas is dispersed by nozzles or spargers without mechanical agitation. In order to improve the operation, redispersion at intei vals may be effected by static mixers, such as perforated plates. The liquid may be clear or be a slurry. 

The models of Chapter 9 contain at least one empirical parameter. This parameter is used to account for complex flow fields that are not deterministic, time-invariant, and calculable. We are specifically concerned with packed-bed reactors, turbulent-flow reactors, and static mixers (also known as motionless mixers). We begin with packed-bed reactors because they are ubiquitous within the petrochemical industry and because their mathematical treatment closely parallels that of the laminar flow reactors in Chapter 8. 

Spinning disc reactor Supercritical fluids Static mixer reactor Reactor... 

To improve the mixing quality in the tubular reactor, Kenics type in-line static mixer reactor was employed. The in-line static mixers were designed to mix two or more fluids efficiently since an improved treinsport process such as flow division, radial eddying, flow constriction, and shear reversal eliminated the gradients in concentration, velocity and temperature. However, only 70 % conversion was achieved with one Kenics mixer unit. As shown in Table 2, five mixer units were required to achieve the maximum conversion. 

Table 2. Production of B0C2-AMP with Kenics in-line static mixer reactor...

Continuous cyclopentenone synthesis with static mixer reactor... 

The high pressure continuous reactor consists of five Kenics type in-line static mixers, that were connected in series [3]. Each reactor unit has 27 Kenics elements and dimensions of 19 cm tube length and 3.3 mm inner diameter. Acetonylacetone and 1 % NaOH aqueous solution were pumped into the in-line static mixer reactor using two independent HPLC pumps. The in-line static mixer reactors were immersed in a constant temperature controlled oil bath at 200 °C so that the reaction mixture was heated to the reaction temperature. When the reaction was completed, the fluid was cooled down rapidly in a constant temperature cold bath at 0 °C. At the end of the cooling line, a backpressure regulator was placed to allow experiments to be run at 34 bar. 

In contrast to this result, polymer samples taken from processing without a micro mixer displayed a small but significant fraction of high-molecular weight polymer with a mass > 10 [126]. Here, in some cases, heavy precipitation occurred, resulting even in plugging of the static-mixer internals of the tube reactors [125]. 

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