Gas enrichment

An enrichment is defined as a separation process that results in the increase in concentration of one or mote species in one product stream and the depletion of the same species in the other product stream. Neither high purity not high recovery of any components is achieved. Gas enrichment can be accompHshed with a wide variety of separation methods including, for example, physical absorption, molecular sieve adsorption, equiHbrium adsorption, cryogenic distillation, condensation, and membrane permeation. 

Britton, L. G. 1996. Operating Atmospheric Vent Collection Headers Using Methane Gas Enrichment. Process Safety Progress, 15(4), 194-212. 

Gas Enrichment The addition of another flammable gas to a gas-air mixture to raise the concentration above the upper flammable limit. 

Several observations show that saturated solutions are at dynamic equilibrium. For example, if O2 gas enriched in the oxygen-18 isotope is introduced into the gas phase above water that is saturated with oxygen gas, the gas in the solution eventually also becomes enriched in the heavier isotope. As another example, if finely divided ciystalline salt is in contact with a saturated solution of the salt, the small crystals slowly disappear and are replaced by larger crystals. Each of these observations shows that molecules are moving between the two phases, yet the concentrations of the saturated solutions remain constant. 

Table 1 lists our abundances of Fe, C, O and a-elements for the observed clusters. An overall excess of a-elements is shared by all the clusters up to solar metallicity, consistent with SNell being responsible for the gas enrichment. Our findings are also in good agreement both with all previous high resolution studies (see [2], [3], [6]) and with recent abundance determinations for field stars in the Galactic Bulge (see [10]). 

Hammel, J. J., W. P. Marshall, W. J. Robertson and H. W. Barch. 1987. Porous siliceous-containing gas enriching material and process of manufacture and use. European Patent Appl. 0,248,931. 

Fig. 26. The production of heavy water is based upon the behavior of deuterium in a mixture of water and hydrogen sulfide. When liquid H2O and gaseous H2S are thoroughly mixed, the deuterium atoms exchange freely between die gas and file liquid. At high temperatures, file deuterium atoms tend to migrate toward file gas, while they concentrate in file liquid at lower temperatures. In the first and second stages of production, file towers of a heavy water plant are operated with the top section cold and file lower section hot. Hydrogen sulfide gas is circulated from bottom to top and water is circulated from top to bottom through the tower. In the cold section, the deuterium atoms move toward file water and are carried downward, while in file hot section, they move toward the gas and are carried upward. The result is that, both gas and liquid are enriched in deuterium at the middle of the tower. A series of perforated trays are used to promote mixing between the gas and water in the towers. A portion of the HjS gas, enriched in deuterium, is removed from file tower at the juncture of file hot and cold sections and is fed to a similar tower for the second stage of enrichment...

A cell model is presented for the description of the separation of two-component gas mixtures by pressure swing adsorption processes. Local equilibrium is assumed with linear, independent isotherms. The model is used to determine the light gas enrichment and recovery performance of a single-column recovery process and a two-column recovery and purification process. The results are discussed in general terms and with reference to the separation of helium and methane. 

Figure k. Light gas enrichment and recovery in product as a function of product cut in single-column PSA process. 

Britton, L.G., Operating atmospheric vent collection headers using methane gas enrichment, Process Safety Progress, 15, No. 4, 1996. 

FukunagaK.,MatsudaJ. i., NagaoK., MiyamotoM., andltoK. (1987) Noble-gas enrichment in vapour-growth diamonds and the origin of diamonds in ureilites. Nature 328(6126), 141-143. 

Use Organic synthesis, household and industrial fuel, manufacture of ethylene, extractant, solvent, refrigerant, gas enricher, aerosol propellant, mixture for bubble chambers. 

Table 4.3 below summarizes the different reservoirs thought to be present in the modern silicate Earth. However, of these, only the depleted mantle and buried eclogitic slabs have compositions which make them directly complementary to the composition of the continental crust. It is suggested here that Archaean SCLM is not closely related in a geochemical sense to Archaean felsic crust but is the product of basalt extraction, basalt which now is emplaced within the Archaean crust. In contrast, Phanerozoic SCLM may be the restite-complement of the basaltic precursor to modern crust. The proposal that there was an early-formed (pre 3.7 Ga), enriched, basaltic crust (Section 4.5.1.2.2), if confirmed, has important implications for the balance between the major Earth reservoirs, not least because the primitive mantle and the bulk silicate Earth can no longer be regarded as com-positionally identical. 

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