EVALUATION OF ENERGETIC AND EXERGETIC PERFORMANCE OF A CRYOGENIC AIR SEPARATION PLANT FOR GENERATING LIQUID OXYGEN : A CASE STUDY

Abstract

A case study is performed for an air separation process. Energy and Exergy analysis are performed to evaluate its parameters and to find out its performance. Energy and exergy methods are employed which enable us to develop a systematic approach that can be used to identify the sites of the real destructions/losses of valuable energy in process. The effect of several design parameters were observed on energy and exergy analysis of the process. The conclusions of the present analysis can be summarized as follows:  The lowest energy efficiency component is the compreesor, which have only 17.9 % efficiency. There are lots of opportunity to increase its efficiency and to use its heat.  The highest energy improvement potenitial is 266.47 KW, which is also for compressor.  Compressor exergy efficiency is also low, which is 67.2 %. This figure shows that there is a large scope to improve its performance.  Maximum exergy destruction has been taken place Compressor , Expansion Engine and Air Separating Column. The total exergy destruction in these three components is 245.35 KW, while the total exergy destruction is 322.02 KW. It is clear from this result that these three components have highest irreversibility in the system which can be improved. From the above results shown, it is possible to find out the component, which needs the development to make the system more effective and more efficient. Energy and Exergy related parameters in the given system have good values. In addition, except the few components Energetic Improvement Potential and Exergetic Improvement Potential of the components are very low. Besides the results shown it is not possible to make larger changes in the Air Separation System. More insulation can be add to minimize the energy loss. Some components can be changed with the more reliable and more efficient components. Another option is to design the Air Separation plant keeping in mind the above results and by simulating it on software such as Aspen Plus to optimize the results.