Packed beds supports

Packed-bed supports. A simple support for a bed of lVfc-in pall rings might consist of a bar grid, with Vi-in-thick bars, set on 1 inch center. The grid itself (see Fig. 7.7) would be supported by two 6-in-wide I-beams. The open area of each component is... 

Leaving tray support rings in towers revamped with packed beds. Poor separation. Premature flooding. Installation error. There are too many examples of this for us to continue to make this one. If you are not confident enough to remove the tray support rings, don t pack the tower. 

Overall distributor height is approximately 24". The distributor is leveled from a supporting grid, which normally restson the top of the packed bed. The vessel manway is usually located at or above the header elevation. 

The typical packed column has one or more beds, each consisting of packing, a support plate, a hold-down support plate, and a liquid distributor. 

Minimum Fluidization Velocity (Umf). The lowest velocity at which the full weight of catalyst is supported by the fluidization gas. It is the minimum gas velocity at which a packed bed of solid particles will begin to expand and behave as a fluid. For an FCC catalyst, the minimum fluidization velocity is about 0.02 ft/sec. 

As well as being active, the immobilised enzyme also needs to be stable (active for a long period) and the support must promote this. The support must also have appropriate mechanical characteristics it should not disintegrate if used in a stirred tank reactor it should produce even flow (without channelling) in a packed bed reactor. Hie cost of the support is also important. 

A further thirty years were to pass before Kuhn and his co-workers (3) successfully repeated Tswetf s original work and separated lutein and xanthine from a plant extract. Nevertheless, despite the success of Kuhn et al and the validation of Tswett s experiments, the new technique attracted little interest and progress continued to be slow and desultory. In 1941 Martin and Synge (4) introduced liquid-liquid chromatography by supporting the stationary phase, in this case water, on silica in the form of a packed bed and used it to separate some acetyl amino acids. 

A commercial pectinase, immobilised on appropriately functionalised y-alumina spheres, was loaded in a packed bed reactor and employed to depolymerise the pectin contained in a model solution and in the apple juice. The activity of the immobilized enzyme was tested in several batch reactions and compared with the one of the free enzyme. A successful apple juice depectinisation was obtained using the pectinase immobilised system. In addition, an endopolygalacturonase from Kluyveromyces marxianus, previously purified in a single-step process with coreshell microspheres specifically prepared, was immobilised on the same active support and the efficiency of the resulting catalyst was tested. 

P 16] An ethanol slurry of activated carbon-supported palladium catalyst particles was introduced into a packed-bed micro reactor [36]. The fraction of 50-75 pm sized particles was used. The reaction was carried out with 1 atm hydrogen at 50 °C. 

Where u, is the mobile phase velocity at the column outlet, Fg the column volumetric flow rate, and Ag the column cross-sectional area available to the mobile phase. In a packed bed only a fraction of the column geometric cross-sectional area is available to the mobile phase, the rest is occupied by the solid (support) particles. The flow of mobile phase in a packed bed occurs predominantly through the interstitial spaces the mobile phase trapped within the porous particles is largely stagnant (37-40). 

The liquid hydrocarbon stream to be treated may be a crude oil, heavy crude oil, bitumen, or a refined fraction of the crude oil. The hydrogen gas stream is added to the mixture of the hydrocarbon stream with the organic solvent. The reactor, which is fed upflow, is a packed bed of biocatalyst dispersed on a support and is operated at about 74°C. Alternatively, the reactor can also be a batch reactor under stirring conditions. 

Grishin, S. I., and Tuovinen, O. H., Scanning Electron Microscopic Examination of Thiobacillus ferrooxidans on Different Support Matrix Materials in Packed Bed and Fluidized Bed Bioreactors, Appl. Microbiol. Biotechnol., 31 505 (1989)... 

Resmi et al. [59] used laterite stones for the immobilization of Pseudomonas putida (MTCC 1194). The amount of bacterial biomass attached to the support was 8.64 g/100 g of stones on dry weight basis. Packed bed reactor was used for treating mixture of seven azo dyes. With the help of immobilized bacterial strain, dye mixture was degraded to nontoxic smaller molecules. It was reported that even after 2 months, bacteria-coated pebbles were stable and suitable for the aerobic degradation of azo dyes. With the help of TLC and HPLC, 61.7% degradation was reported at the concentration of 50 pg/mL of dye. 

---