الفهرس 
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Abstract
Cryogenic air separation is used to provide high purity products. In the present work,design and simulation of acrogenic air separation and liquefaction plant were donewithout using cold box before first column and all feed air separated to nitrogen with99.3% mole purity, 100% oxygen and 99.6% argon in liquid form.Process was simulated by using ASPEN HYSYS simulating tool and the total electricenergy consumption per kilogram of liquid products was 0.657 kw.hr/kg liq.Cryogenic air separation is the process with high energy consumption. So exergy analysiswas done to improve the second low efficiency of the process. The exergy efficiency isdefined as the desired change in exergy contents of the ASP products divided by the netamount of added work. The exergy analysis of the cryogenic air distillation plant haspinpointed and quantified the exergy loss in the different plant sections. Most of the exergydestruction is located in the compressor after-coolers. Also exergy analysis shows that57.3% of exergy destruction locate in auxiliary liquefaction cycles (especially in O2ARcycle), and 34.6% in distillation section. The exergy loss can be reduced by 15% at least ifwe increase the compressors polytropic efficiency by 87% and use high efficiencyintercoolers. Also if we duplicate the number of compressors stages with inter coolers,power consumption will reduced by 10%. If we take all these recommendation intoconsideration the total energy consumption will be 0.59 kw.hr/kg liq.