Exergy and energy analysis of a load regulation method of CVO of air separation unit

Lige Tong, Aijing Zhang, Yongliang Li, Li Yao, Li Wang, Huazhi Li, Libing Li, Yulong Ding

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Generally in the Chinese iron and steel industry, the electricity consumption of cryogenic air separation unit (ASU) is about 14% of the overall electricity use. To reduce the electricity consumption, the combined variable oxygen (CVO) supply method for ASU is proposed. The exergy calculation program for ASU was developed and the detailed analysis of CVO method was performed. The results show that the general exergy efficiency (GEE) of ASU combined with a liquefaction unit is increased by 11 %–31 %. The consumption of unit oxygen, the total electricity consumption and the overall consumption of unit oxygen (OCUO) was compared. The OCUO is a suitable method to evaluate the energy-saving potential of CVO. Compared with the load regulation method of Automatic Load Control (ALC), the OCUO and the unit consumption of compression of CVO reduced more than 4.47% and 30%, respectively. It means that CO2 emission of every reduction 1% of gaseous oxygen release in a year in Chinese iron and steel industry will contribute approximately 0.75% to the 2020s CO2 emission reduction target of China.
Original languageEnglish
Pages (from-to)413-423
JournalApplied Thermal Engineering
Early online date7 Feb 2015
Publication statusPublished - 5 Apr 2015


  • Air separation unit
  • Variable load
  • Exergy analysis
  • Energy consumption
  • CO2 emission


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