Hybrid processing

Hybrid Crystallization/Adsorption Process. In 1994, IFP and Chevron announced the development of a hybrid process that reportedly combines the best features of adsorption and crystallization (59,99). In this option of the Eluxyl process, the adsorbent bed is used to initially produce PX of 90—95% purity. The PX product from the adsorption section is then further purified in a small single-stage crystallizer and the filtrate is recycled back to the adsorption section. It is reported that ultrahigh (99.9+%) purity PX can be produced easily and economically with this scheme for both retrofits of existing crystallization units as well as grass-roots units. A demonstration plant was built at Chevron s Pascagoula refinery in 1994. 

Advances in fundamental knowledge of adsorption equihbrium and mass transfer will enable further optimization of the performance of existing adsorbent types. Continuing discoveries of new molecular sieve materials will also provide adsorbents with new combinations of useflil properties. New adsorbents and adsorption processes will be developed to provide needed improvements in pollution control, energy conservation, and the separation of high value chemicals. New process cycles and new hybrid processes linking adsorption with other unit operations will continue to be developed. 

Paper technology-based nonwoven processes provide the least product versatitity and require a high investment at the outset, but yield outstandingly uniform products at exceptional speeds. Hybrid processes provide combined technological advantages for specific apptications. 

Hybrid Processes. There are also hybrid processes that have evolved to meet specific product needs. As an example, automotive leaf springs utilize a filament winding system to prepare impregnated fiber bundles that are then compression molded to final configuration. 

RO is also used to produce ultrapure water for many laboratory uses (90) as weU as in the medical and pharmaceutical industries (91). As for the electronics industry, purity is achieved using a combination of processes. A typical hybrid process for the production of ultrapure water is shown in Figure 11. The order in which the various steps take place may vary from case to case. 

Fig. 11. Schematic of membrane-based hybrid process for ultrapure water production.

Hybrid Processes. A number of processes have been developed which use both chemical and physical absorption solvents to offer high purity treat gas and low energy solvent regeneration. The operation of these processes is usually similar to that of the individual chemical or physical absorption processes. The solvent composition is typically customized to meet the requirements of individual appHcations. 

Trends in ED appear to be reduction in pumping and direct ED energy, increase in electric current density, and the use of EDR and hybrid processes in plants in which the manufacturer of the demineralisation plant owns and operates the plant, selling water to the user or water distributor. 

Leading Examples Electrodialysis has its greatest use in removing salts from brackish water, where feed salinity is around 0.05-0.5 percent. For producing high-purity water, ED can economically reduce solute levels to extremely low levels as a hybrid process in combination with an ion-exchange bed. ED is not economical for the produc tion of potable water from seawater. Paradoxically, it is also used for the concentration of seawater from 3.5 to 20 percent salt. The concentration of monovalent ions and selective removal of divalent ions from seawater uses special membranes. This process is unique to Japan, where by law it is used to produce essentially all of its domestic table salt. ED is very widely used for deashing whey, where the desalted product is a useful food additive, especially for baby food. 

After the hybridization process, intensity signals from the hybridized RNA/cDNA samples are usually detected by phospho-imaging or fluorescence scanning and independent images are generated. 

A CVD reaction can occur in one of two basic systems the closed reactor or the open reactor (also known as close or open tube). The closed-reactor system, also known as chemical transport, was the first typetobeusedforthe purification of metals. It is a hybrid process which combines vapor-phase transfer with solid-state diffusion. As the name implies, the chemicals are loaded in a container which is then tightly closed. A temperature differential is then applied which provides the driving force for the reaction. 

Fig. 1 Integral hybrid process flow diagram MFAJV/NF for regeneration of WWTP effluents...

Table 4 summarizes the efficiency of membrane filtration as preliminary treatment in the hybrid process to obtain regenerated water for industrial reuse. Working with the adequate cleaning cycle to avoid fouling and to keep a constant flux (10 1 min ) important reduction in suspended solids (90%) and turbidity (60%) of the wastewaters is achieved but there is no significant reduction of other chemical or physical parameters, e.g., conductivity, alkalinity or TDS, or inactivation of E. coli. 

Table 5 Membrane specifications and operation conditions for UF stage in WWTP hybrid process for industrial reuse water reclamation...

The number of valence orbitals generated by the hybridization process equals the number of valence atomic orbitals participating in hybridization. 

Hammer, Th., Kappes, Th. and Baldauf, M. (2004) Plasma catalytic hybrid processes gas discharge initiation and plasma activation of catalytic processes, Catal. Today 89, 5-14. 

Lee, Y.H., Chung, J.W., Choi, Y.R. et al. (2004) NOx removal characteristics in plasma plus catalyst hybrid process, Plasma Chem. Plasma Process 24, 137-54. 

The desulfurization process reported by the authors was a hybrid process, with a biooxidation step followed by a FCC step. The desulfurization apparently occurs in the second step. Thus, the process seems of no value, since it does not remove sulfur prior to the FCC step, but only oxidizes it to sulfoxides, sulfones, or sulfonic acids. The benefit of such an approach is not clearly outlined. The benefit of sulfur conversion can be realized only after its removal, and not via a partial oxidation. Most of the hydrotreatment is carried out prior to the FCC units, partially due to the detrimental effect that sulfur compounds exert on the cracking catalyst. It is widely accepted that the presence of sulfur, during the regeneration stage of the FCC units, causes catalyst deactivation associated with zeolite decay. In general terms, the subject matter of this document has apparent drawbacks. 

Their activities in desulfurization lead to a hybrid process, protected under the title of Method for electrobiologically desulfurizing petroleum [143], awarded to the Marine Biotechnology Institute by the Japanese Patent Office [143], This method is based on contacting anaerobic sulfur-oxidizing bacteria with petroleum under anaerobic condition or microaerophilic conditions. The bacteria used belonged to Proteobacteria or Thiomicrospira bacteria. 

Hybridization Process of joining two complementary strands of DNA or one each of DNA and RNA to form a double-stranded molecule. 

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