Process for air separation

The concept is to use frister cycle times (seconds) than those used by the conventional PSA cycles (minutes) in order to obtain a step change in the productivity of the process (volume of product/volume of adsorbent our). Some of these designs use a conventional PSA cycle but they are operated faster by appropriate changes in the mechanical designs [6]. Others, propose novel process schemes in order to accommodate t cycle times [7-9]. An example of the second case is a RPSA process for air separation where a single adsorber vessel is packed with two or more (even numbers) shallow layers of small zeolite particles (-0.5 mm). The layers are separated... 

Krypton and Xenon are valuable gases present in very low concentrations in air. U.S. 6,662,593 assigned to Air Products describes a cryogenic distillation process for air separation with recovery of a stream concentrated in Kypton and Xenon. What would be the cost of producing purified Krypton and Xenon by this method Consider reactive methods for separating Krypton and Xenon from the concentrated stream as well as the methods suggested in the patent. 

Thermal coupling of columns is often used in industrial processes since it effectively reduces the energy demand by multiple use of the external heat supplied. An interesting example is the Linde Process for air separation (Fig. 11.2-18). In this... 

Fig. 11.2-18 Simplified Linde process for air separation and argon recovery...

Nine different PSA processes for air separation using zeolites are reviewed and their process performances are compared. These processes can be designed to produce low (23-50 mole%) and medium purity (90-95 mole%) 02-enriched air and high purity (98+ mole%) N2-enriched air. Processes can be tailor made to match the adsorptive properties of the zeolite for a given separation need or vice versa. 

PSA processes for air separation differ by (a) the type of zeolite used,... 

The above-described (idealized and simplified) effects of zeolite N2 capacity and selectivity on the adsorption and desorption processes for air separation clearly demonstrate that the selection of the optimum zeolite for a given PSA process or designing an optimum process for a given zeolite can be fairly complex. 

Consequently, water must be removed from the ambient air before the zeolite can carry out the N2-O2 separation. This is typically done by using a water selective desiccant like activated alumina or NaX zeolite for selectively removing the water from air. The desiccant generally forms an integral part of the zeolite PSA process for air separation (a layer of the desiccant followed by the zeolite layer in the same column or in two separate columns). The ratio of the... 

Figure 6.36. Combined measurements of the gas pressure and the (real part of the) dielectric capacitance at v = 10 MHz of a capacitor filled with MSNal3X (UOP) inside a commercially operating VSA-process for air separation (Mahler AG) [6.15]. Changes in the gas pressure and the capacitance are due to ad- and desorption of nitrogen (N2) on the sorbent.

Figure 6.2.5 Unde process for air separation by distillation with a double column. Adapted from Stichimair and Fair (1998) and Baerns eta/. (2006) E heat exchanger, C column.

Figure 7.1 Basic plant layout of two-bed PSA process for air separation.

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