Helium Separations

Like hydrogen, hehum has high selectivity against most other components present in its mixtures for a wide variety of polymers. The primary source of hehum is natural gas reservoirs usually in concentrations below 1%. Considering that the low concentrations translate to low partial pressures, it can be seen that membranes find hmited appHcation in helium production since multiple stages would be required to reach even crude helium purity levels. 

Membranes have found appHcation in helium gas recovery. Deep-diving gases employ helium mixtures that become contaminated. A combination of membranes and adsorbents are employed in purification of these gases for reuse. Small membrane systems are also employed in the purification of helium used in blimps. With time, the hehum gas that inflates these hghter-than-air craft becomes contaminated with atmospheric gases. These contaminants are readily rejected by operating a small compressor and membrane unit to reject the contaminants and return purified helium to the craft. 

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I eon—Helium Separation and Purification. As indicated eadier, neon, heHum, and hydrogen do not Hquefy in the high pressure (nitrogen) column because these condense at much lower temperatures than nitrogen. As withdrawn, the noncondensable stream has a neon—helium content that varies 1—12% in nitrogen, depending on the rate of withdrawal and elements of condenser design and plant operation. 

The polyphenol oxidase was obtained from extracts of the pressed grape juice sediment by acetone precipitation, purified on Sephadex G 25 and DEAE-Sephadex A 25, and further concentrated by ultrafiltration. Model experiments were done in a Warburg apparatus (10). The grape skin waxes were extracted with pentane. The resulting extracts were analyzed by a GLC (Varian Aerograph, model 1201) which was coupled via a helium separator according to Watson and Bieman (19) to a mass-... 

An example of the effect of pressure on the performance of the single column process for the methane-helium separation is shown in Table 1. Using Figure 4(b) and 4(d), the cuts corresponding to 80 percent recovery of helium were determined as a function of yF and Pr L Then the enrichments and in... 

Plate-fin exchangers provide a very large heat transfer surface per unit volume and are relatively inexpensive per unit area. They are not mechanically cleanable and are ordinarily used only with very clean fluids. This combination of properties fits them very well for a wide variety of cryogenic applications, such as air separation helium separation, purification, and liquefaction liquefied natural gas production and separation of light hydrocarbons. They are also used in higher-temperature gas-to-gas services. 

K.V. Peinemann, K. Fink, P. Witt, Asymmetric Polyetherimide Membranes for Helium Separation, Journal of Membrane Science 27 (1986) 215. 

Helium sealing oil 4 Air oil storage tank 7 Helium separation tank 10 Helium/bearing oil... 

Fig. 6.39. Schematic diagram of a United States Bureau of Mines helium separation plant.

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