Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
권호 표지
DOI QR코드

DOI QR Code

A Study on the Optimal Process Design of Cryogenic Air Separation Unit for Oxy-Fuel Combustion

순산소 연소를 위한 초저온 공기분리장치의 최적공정 설계 연구

  • Choi, Hyeung-Chul (Daesung Cryogenic Research Institute, Daesung Industrial Gases Co., Ltd.) ;
  • Moon, Hung-Man (Daesung Cryogenic Research Institute, Daesung Industrial Gases Co., Ltd.) ;
  • Cho, Jung-ho (Department of Chemical Engineering, University of Kongju)
  • 최형철 (대성산업가스(주) 초저온연구소) ;
  • 문흥만 (대성산업가스(주) 초저온연구소) ;
  • 조정호 (공주대학교 화학공학부)
  • Received : 2018.07.11
  • Accepted : 2018.08.14
  • Published : 2018.10.01
Download PDF
⟨ Previous Next ⟩

Abstract

In order to solve the global warming and reduce greenhouse gas emissions, it has been developed the $CO_2$ capture technology by oxy-fuel combustion. But there is a problem that the economic efficiency is low because the oxygen production cost is high. ASU (Air Separation Unit) is known to be most suitable method for producing large capacity of oxygen (>2,000 tpd). But most of them are optimized for high purity (>99.5%) oxygen production. If the ASU process is optimized for low purity(90~97%) oxygen producing, it is possible to reduce the production cost of oxygen by improving the process efficiency. In this study, the process analysis and comparative evaluation was conducted for developing large capacity ASU for oxy-fuel combustion. The process efficiency was evaluated by calculating the recovery rate and power consumption according to the oxygen purity using the AspenHysys. As a result, it confirmed that the optimal purity of oxygen for oxyfuel combustion is 95%, and the power consumption can be reduced by process optimization to 12~18%.

지구 온난화 문제 해결과 온실가스 감축을 위하여 화력발전소를 중심으로 순산소 연소를 통한 $CO_2$ 포집 기술이 개발되었으나, 산소 생산 비용이 높아 경제성이 떨어지는 문제를 가지고 있다. 순산소 연소에 필요한 대량의 산소(>2,000 tpd)를 생산하는 방법은 초저온 공기분리장치(ASU: Air Separation Unit)가 가장 적합한 것으로 알려져 있으나, 대부분 고순도(>99.5%) 산소 생산에 최적화되어 건설되었다. 이런 초저온 공기분리장치에서 순산소 연소에서 사용이 가능한 낮은 순도(90~97%)의 산소를 생산하고 공정을 최적화할 경우, 공정 효율이 높아져 산소 생산 비용 절감이 가능하다. 본 연구에서는 순산소 연소 발전시스템에 산소를 공급할 수 있는 초대형(>2,000 tpd $O_2$) ASU 개발을 위하여 공정 분석 및 비교 평가를 수행하였다. 상용 프로그램인 AspenHysys를 이용하여 산소 순도에 따른 회수율 및 전력소모량을 계산하고 공정의 효율을 평가하였다. 그 결과 ASU를 통해 순산소 연소에 공급되는 산소는 약 95%가 최적이며, 생산 공정 최적화 시 약 12~18%의 전력소모량 절감이 가능한 것을 확인 할 수 있었다.

Keywords

References

  1. Barron, R. F., "Cryogenic systems., 2nd ed.," Monographs on Cryogenics, New York: Oxford University Press(1985).
  2. Yong, P. S., Moon, H. M., Son, M. R. and Yi, S. Chul., "A Reliability of Equation of State for Nitrogen, Oxygen and Argon," J. of KIGAS 1(1), 41-48(1997).
  3. Yong, P. S., Moon, H. M. and Yi, S. Chul., "A Study on the Development of a Cryogenic Air Separation Unit to produce High purity Nitrogen," J of KIASC, 3(1), 69-73(2001).
  4. IEA Report 2005/9, "Oxy Combustion Processes for $CO_2$ Capture from PowerPlant"(2005).
  5. Harry, C and Williamsville, N. Y., "Side Column Cryogenic Rectification System for Producing Lower Purity Oxygen," U.S Patent, 5,463,871(1995).
  6. Rakesh, A., Zbigniew, E. and Macungie, T. F., "Three Column Cryogenic Cycle for the Production of Impure Oxygen and Pure Nitrogen," U.S Patent, 5,682,764(1997).
  7. Allam, R. J., "Improved Oxygen Production Technologies," Energy Procedia, 1(1), 461-470(2009). https://doi.org/10.1016/j.egypro.2009.01.062
  8. Higginbotham, P., White, V., Fogash, K. and Guvelioglu, G., "Oxygen Supply for Oxycoal $CO_2$ Capture," Energy Procedia, 4, 884-891(2011). https://doi.org/10.1016/j.egypro.2011.01.133
  9. Fu, C. and Gundersen, T., "Using Exergy Analysis to Reduce Power Consumption in Air Separation Units for Oxy-combustion Processes," Energy, 44(1), 60-68(2012). https://doi.org/10.1016/j.energy.2012.01.065
  10. Lee, H. K., Choi, S. M., Moon, H. M., Seo, S. I., "Proposed Process and Design Considerations for Air Separation and $CO_2$ Purification in a 100MWe Oxy-Coal Power Generation System," Energy Technology, 1, 217-225(2013). https://doi.org/10.1002/ente.201200017
  11. Ebrakimi, A., Meratizaman, M., Reyhani, H. A., Pourali, O. and Amidpour, M., "Energetic, Exergeric and Economic Assessment of Oxygen Production from Two Columns Cryogenic Air Separation Unit," Energy., 90, 1298-1316(2015). https://doi.org/10.1016/j.energy.2015.06.083
  12. Aspen Technology, "AspenHysys Thermodynamics V.8.8," (2015).
  13. Hankinson, R. W., Thomson, G. H. and Brobst, K. R., "An Improved Correlation for densities of Compressed Liquids and Liquid Mixtures," AIChE J., 28(4), 671-676(1982). https://doi.org/10.1002/aic.690280420