Extraction systems

As small droplets of liquid are usually still present in the gas phase, demisting secWons are required to recover the liquid mist before it is carried over" in the gas stream out of the separator. The largest liquid droplets fall out of the gas quickly under the action of gravity but smaller droplets (less than 200 microns) require more sophisticated extraction systems. 

Miscellaneous Pharmaceutical Processes. Solvent extraction is used for the preparation of many products that ate either isolated from naturally occurring materials or purified during synthesis. Among these are sulfa dmgs, methaqualone [72-44-6] phenobarbital [50-06-6] antihistamines, cortisone [53-06-5] estrogens and other hormones (qv), and reserpine [50-55-5] and alkaloids (qv). Common solvents for these appHcations are chloroform, isoamyl alcohol, diethyl ether, and methylene chloride. Distribution coefficient data for dmg species are important for the design of solvent extraction procedures. These can be determined with a laboratory continuous extraction system (AKUEVE) (244). 

Immersion extraction systems are usefiil in handling finely ground material or when the percolation rate through the material to be extracted is too rapid to aUow effective diffusion from the soHds. These systems are appHed extensively in the sugar industry, in extraction from oilseeds having a high oil... 

Larch Gum. Larch gum [37320-79-9] (larch arabinogalactan) is obtained by water extraction of the western larch tree, iLarix occidentalism the heartwood of which contains 5—35% on a dry wood basis. In the early 1960s, a countercurrent hot water extraction system was developed, and the gum was produced commercially by the St. Regis Paper Co. under the trade name Stractan. The potential production capacity of this gum is 10,000 t/yr based on the wood residues from the lumber industry. However, the product could not compete with gum arabic, and commercial production is now limited to small batches for a specific medical appHcation. 

Another characteristic of the solvent extraction system is the high solute concentration in both aqueous and organic phases, which influences greatly the size of the required installation. Concentrations of rare-earth oxides (REO) higher than 100 g/L are often reached in both phases. The process therefore requires only relatively small equipment. 

S. B. Watson md R. H. Rmney, Modfcations of the SEPHIS Computer Code for Calculating the Purex Solvent Extraction System, ORNL/TM-5123, Oak Ridge National Laboratory, Oak Ridge, Term., 1975. 

Nuclear Waste. NRC defines high level radioactive waste to include (/) irradiated (spent) reactor fuel (2) Hquid waste resulting from the operation of the first cycle solvent extraction system, and the concentrated wastes from subsequent extraction cycles, in a faciHty for reprocessing irradiated reactor fuel and (3) soHds into which such Hquid wastes have been converted. Approximately 23,000 metric tons of spent nuclear fuel has been stored at commercial nuclear reactors as of 1991. This amount is expected to double by the year 2001. 

Organ oselenium compounds, such as phosphine selenides, are being evaluated in solvent extraction systems for silver and gold (63). Also, potential pharmaceuticals containing selenium have been prepared (64). 

Slater, Rate Coefficients in Liquid-Liquid Extraction Systems in Godfrey and Slater, Liquid-Liquid Extraction Equipment, Wiley, 1994, pp. 45-94. 

The overall stage efficiency of a staged extraction system is simply the number of theoretical stages divided by the number of actual stages times 100 [Eq. (15-28)]. 

In the liquid-hquid extraction area, in the mining industry, coming out of the leach tanks is normally a slurry, in which the desired mineral is dissolved in the liquid phase. To save the expense of separation, usually by filtration or centrifugation, attempts have been made to use a resident pump extraction system in which the organic material is contacted directly with the slurry. The main economic disadvantage to this proposed system is the fact that considerable amounts of organic liquid are entrained in the aqueous slurry system, which, after the extraction is complete, is discarded. In many systems this has caused an economic loss of solvent into this waste stream. 

However, it is possible to use two-dimensional spectra in spectrophotometry as an alternative. In this case, the pH value of the water phase in extracting systems is used as a supplementary coordinate. 

Strkcttire inflkence. The specificity of interphase transfer in the micellar-extraction systems is the independent and cooperative influence of the substrate molecular structure - the first-order molecular connectivity indexes) and hydrophobicity (log P - the distribution coefficient value in the water-octanole system) on its distribution between the water and the surfactant-rich phases. The possibility of substrates distribution and their D-values prediction in the cloud point extraction systems using regressions, which consider the log P and values was shown. Here the specificity of the micellar extraction is determined by the appearance of the host-guest phenomenon at molecular level and the high level of stmctural organization of the micellar phase itself. 

Separation of Am(III) and Cm(III) from aqueous acidic nitrate media by CCC using two different extraction systems have been studied ... 

Dionex Corporation - Manufacturers of liquid chromatography systems (IC and HPLC), chromatography software data systems, reversed-phase and ion-exchange columns, and accelerated solvent extraction systems... http //www.dionex.com. 

Fixed cost of extraction system associated with S2, = 120,000 (Rowrate of wastewater,... 

The Brio refining site is approximately 58 acres in size and is the location of a former chemical production, recovery, refinery, and regeneration facility. The site includes closed impoundments into which hazardous substances were disposed in bulk, storage tanks, and approximately 1,750 drums of hazardous substances. Remediation activities included the excavation and incineration of contaminated soil, installation of protective liners around selected pits, and the installation of a groundwater extraction system adjacent to a gully. 

These include, for example, smoke extraction systems. In ventilation and air conditioning systems certain equipment can also require special safety measures (e.g., due to explosion risks). 

Feed-forward (compensating) of air or water temperature from outdoor temperature or for input or extract systems... 

The materials of construction, from the cupboard to the fan, should be inorganic and resistant to attack by perchloric acid. For the cupboard itself suitable materials include stainless steel of types, 316 or 317, solid epoxy resin, and rigid PVC. Stainless steel has been popular for this application as it is easy to form, weld, and polish. It is, however, attacked by the acid, which causes discoloration of the metal surface and the formation of iron(III) perchlorate, which can be explosive. Ductwork, separate from other extract systems, is usually made from stainless steel or plastic materials. Fire regulations may preclude the use of plastic ductwork or require it to be sheathed in an outer casing of metal or GRP. The fan casing and impeller can both be made of plastic. 

Conditions Downstream of the Cupboard Variations in conditions downstream of the cupboard may affect the performance of the cupboard. The variations can arise from three causes atmospheric conditions, multi-extract systems, and VAV controls. 

F. F. L. Morgan. Dust extraction systems for surface grinding wheels. U.S. Patent no, 2 819 571. W ashington, DC Patent Office, 1958. 

The influence of parameter variation is to be investigated (e.g., to optimize a local extract system). 

VOCs are released during chemical cleaning of bonding surfaces. The extract system is designed on the basis of the steady-state concentration determined for maximum source strength and considering the mechanical extract ventilation only and no air-exchange with the assembly hail. Ehis concentration must be kept below the threshold concentration (TVL) which is set to 300 mg/kg in this example. 

FIOURE M.43 The fectory buMdmg with the two haJmechanical extract system. 

Flux, J.H. Modelling Studies of Roof Extraction Systems for Arc Furnace Melting Shops. To. x-eraboLirg E.S.C. (Sept. 1974). 

Grease A filter used in kitchen air extraction systems to prevent the contamination of the ductwork system with grease, which would be a fire hazard. 

Hood entry loss The pressure drop (energy loss) that occurs due to turbulence at the entrance to the extraction system. 

Initial Extraction Technique Continuous extraction apparatus was employed, including an extractor designed to contain the starting plant materials, a distillation flask to hold the solvent mixture, the flask being equipped with a reflux condenser, a drip device to facilitate the removal of the volatilized mixture from the condenser and to percolate it through the continuous extractor, and a Soxhiet type return. Means for heating the continuous extraction system were provided. 

Industrial ventilation A term used to cover any ventilation system designed to remove contaminants. Its use is sometimes restricted to local extract systems. Infiltration Movement of air through a space with no specific ventilation openings by natural forces. 

This falls into two basic groupings supply air systems and extract systems. The equipment used for both is similar, comprising, as a minimum, a fan and weatherproof cowl, plus ducting, air-treatment equipment and grilles as required. 

Local extract systems are designed specifically to remove fumes, dust, mists, heat, etc. at source from machinery and fume cupboards. The main design considerations are capture of the contaminant, which will normally involve special hoods or cabins, and extract at sufficient velocity... 

It is generally only practical to ventilate office spaces by means of a ducted system. If sufficient opening window area is available, either an inlet or extract system alone may be satisfactory, but if optimum control of conditions is required, then both mechanical inlet and extract should be provided. 

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