Photoreactor annular

Shen et al. (1995) investigated the effect of light absorbance on the decomposition of aqueous chlorophenols (CPs) by UV/H202. The photoreaction system was batch annular photoreactors with 254-nm, low-pressure UV lamps at 25°C. The light absorbance and photolytic properties of chlorophenols and H202 were found to be highly dependent on the solution pH and can be adequately described with the linear summation of the light absorbance of undissociated and dissociated species of chlorophenols ... 

The obtained results have shown that the configuration where the recirculation tank was irradiated and the catalyst was used in suspension appeared to be the most interesting for industrial applications [73]. Moreover, it was observed that the degradation rate was higher when an immersed lamp was used compared to a system with an external lamp [81]. Therefore, actually the studies in progress are realized in the system described elsewhere [39] consisting of a Pyrex annular photoreactor with a 125-W medium-pressure Hg lamp axially positioned inside the reactor. The separation module containing the flat-sheet membrane was connected to the photoreactor in a recirculation loop. 

Equation (45) can be solved by applying different photoreactor models. The literature reports several photochemical reactor models for both homogeneous and heterogeneous reactors [11,108,109]. In practice, annular photoreactors are often used (see Fig. 5) therefore, models for this type of reactor are considered here. For other types of reactors, attention should be given to other publications [109]. 

Fig. 8.3 Cross-sectional view and top-view of various photoreactor types with different arrangement of the lamps. A Continuous flow annular photoreactor with coaxial lamp position, B external lamp position with reflector (R), C perpendicular lamp position D contact-free photoreactor types. The possible ar-...

Fig. 8.4 Continuous flow annular photoreactor with external spiral shaped lamp position reproduced by permission of UMEX GmbH (Dresden, Germany).

Annular photoreactor H2O2-UV UV fluence rate distribution Bolton (2000)... 

Annular photoreactor uv Radiation intensity models Suidan and Severin (1986)... 

Irazoqui HA, Cerda J, Cassano AE (1973) Radiation Profiles in an Empty Annular Photoreactor with a Source of finite Spatial Dimensions, AIChE J. 19, No. 3 460-467. 

Photocatalytic reactions are promoted by solid photocatalyst particles that usually constitute the discrete phase distributed within a continuous fluid phase in the reactor. Therefore, at least two phases, that is, liquid and solid, are present in the reactor. The solid phase could be dispersed (SPD) or stationary (SPS) within the reactor. SPD photoreactors may be operated with the catalyst particles and the fluid phase(s) agitated by mechanical or other means. Depending on the means of agitation, the photoreactor resembles that of slurry or fluidized bed reactors. In numerous investigations, an aqueous suspension of the catalyst particles in immersion or annular-type photo reactors has been used. However, the use of suspensions requires the... 

Figure 6.1 Geometry of the continuous flow, annular photoreactor. Adapted from Cassano...

A pilot plant scale, tubular (annular configuration) photoreactor for the direct photolysis of 2,4-D was modeled (Martin etal, 1997). A tubular germicidal lamp was placed at the reactor centerline. This reactor can be used to test, with a very different reactor geometry, the kinetic expression previously developed in the cylindrical, batch laboratory reactor irradiated from its bottom and to validate the annular reactor modeling for the 2,4-D photolysis. Note that the radiation distribution and consequently the field of reaction rates in one and the other system are very different. 

Irazoqui H.A., Cerda J. and Cassano A.E. 1973. Radiation profiles in an empty annular photoreactor with a source of finite spatial dimensions, AIChE J., 19, 460-467. 

Romero R.L., Alfano O.M., Marchetti J.L. and Cassano A.E. 1983. Modelling and parametric sensitivity of an annular photoreactor with complex kinetics, Chem. Eng. Sci., 38, 1593-1605. 

Figure 26.1 Examples of basic photochemical reactors (some adapted from Cassano et al., 1995). (a) tubular photoreactor inside a cylindrical reflector of elliptical cross section (b) annular photoreactor (c) film-type photoreactor (d) single-lamp multitube continuous photoreactor (e) perfectly-mixed semibatch cylindrical photoreactor irradiated from the bottom by a tubular source and a parabolic reflector...

The experimental plant consisted of an annular photoreactor with an immersed UV lamp connected with the permeation cell in which a pressurized flat sheet membrane or a submerged membrane module was located. 

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