Several tasks related to the use of xenon (Xe) and neon (Ne) isotopes were formulated at the end of the 20th century [1]. Xe has nine stable isotopes ( 124 Xe, 126 Xe, 128 Xe, 129 Xe, 130 Xe, 131 Xe, 132 Xe, 134 Xe, 136 Xe); Ne, three ( 20 Ne, 21 Ne, 22 Ne) [1, 2].The separation coeffi cient can be used to evaluate technical and economic factors of the process for separating a binary gas mixture [1, 3] and is approximated for diffusion separation of a mixture (through a porous diaphragm) as [1,4] (1)where M h and M l are the molecular masses of the heavy and light components, respectively.Equation (1) is valid for Knudsen fl ow through a porous diaphragm. The separation coeffi cients for the binary mixtures 20 Ne-21 Ne, 20 Ne-22 Ne, and 21 Ne-22 Ne are k s 20-21 ≅ 1.0247, k s 20-22 ≅ 1.0488, k s 21-22 ≅ 1.0235, respectively. The separation in one stage is miniscule; however, it can be increased by combining diffusion cells [5]. The mole ratio 20 Ne: 22 Ne ≈ 9.8:1.0 or y 22 Ne ≈ 0.092 is used for estimating the number of diffusion cells (number of contact stages) for separating the 20 Ne-22 Ne mixture. The separation coeffi cient of the mixture is set to k s 20-22 ≅ 1.0488 = const whereas k s 20-22 ≅ 1.0200 for comparison. Figure 1 shows the required number of diffusion cells (calculated by the literature method [6]). Stable Xe isotopes are produced in Russia mainly by centrifuge technology [1]. The separation coeffi cient for a binary mixture of ideal gases by centrifuge technology (at constant temperature) is [1](2) where ϖ is the angular velocity; a, the rotor radius; T, the temperature; and R, the gas constant.
The possibility of a change in the desorption kinetics of an adsorbate from an adsorbent granule is demonstrated with the use of solid-electrolyte cells. A description of the experimental bench created for measurement of kinetic curves is given for adsorbate adsorption from an adsorbent granule. Results of test changes in the kinetic curves are presented for oxygen desorption from a granule of a carbon-molecular sieve (UMS-1).Intensified utilization of adsorption plants for cleaning and separation of gaseous mixtures is closely associated with the appearance of a heat-free procedure for regeneration of PAS adsorbent [1]. This is dictated by the relative simplicity of the process flow diagrams of these plants, and, accordingly, the relative simplicity of their operation.In PSA plants, the duration of the adsorption-equipment cycle is small (several seconds and less) [2]; these short cycles are possible owing to low sluggishness of the unheated procedure for regeneration of the layer of adsorbent (as compared with the heated procedure). The kinetics of the adsorption and desorption processes is critical for practical realization of short-duration adsorption. Primary experimental information allowing for estimation of mass-transfer coefficients is required for reliable analysis of these processes and equipment.The numerical value of the coefficient of internal mass-transfer (within a granule of the adsorbent) determines the form of the sorption-kinetics equation that enters into the system of equations for calculation of parameters of the adsorption equipment. This study is conducted within the framework of systematic investigation of the air-separation process by the method of adsorption.It should be pointed out that in PSA plants the duration of adsorbate desorption (at a temperature T ≅ const) is equal to or exceeds the duration of absorption of the absorptive by the adsorbent [3,4]. A pilot study of the kinetics of adsorbate desorption for various adsorption systems, including for nitrogen-oxygen-carbon-molecular-sieves (UMS) systems, is extremely urgent.Experimental methods of investigating adsorption kinetics are well known. Conversely, there are essentially no methods for investigation of the desorption kinetics of adsorbate from a granule of adsorbent, and the experimental equipment required for their realization [5,6].Type UMS adsorbents for which the separation of a nitrogen-oxygen mixture due to the high diffusion rate of oxygen in granules of adsorbent as compared with diffusion of nitrogen, are used in adsorption air-separation plants for the produc-
The method of separation of a Ne-He mixture on a membrane made from quartz glass with the goal of obtaining a high-concentration of He is an alternative to the cryogenic method and has advantages such as relatively low production cost per unit product; simple separator module design; does not require cooling down to cryogenic temperatures.The basic problems in studies of this method are: determination of the effect of external parameters (the flow rate of
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