Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Techno-economic Analysis and Environmental Impact Assessment of a Green Ammonia Synthesis Process Under Various Ammonia Liquefaction Scenarios

암모니아 액화 시나리오에 따른 그린암모니아 합성 공정의 경제성 및 환경 영향도 평가

  • Gunyoung Kim (School of Chemical Engineering, Chonnam National University) ;
  • Yinseo Song (School of Chemical Engineering, Chonnam National University) ;
  • Boram Gu (School of Chemical Engineering, Chonnam National University) ;
  • Kiho Park (Department of Chemical Engineering, Hanyang University)
  • 김건영 (전남대학교 화학공학부) ;
  • 송인서 (전남대학교 화학공학부) ;
  • 구보람 (전남대학교 화학공학부) ;
  • 박기호 (한양대학교 화학공학과)
  • Received : 2024.01.09
  • Accepted : 2024.04.03
  • Published : 2024.05.01
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Abstract

In this study, two different scenarios for ammonia liquefaction in the green ammonia manufacturing process were proposed, and the economic-feasibility and environmental impact of each scenario were analyzed. The two liquefaction processes involved gas-liquid separation before cooling at high pressure (high pressure cooling process) or after decompression without the gas-liquid separation (low pressure cooling process). The high-pressure cooling process requires higher capital costs due to the required installation of separation units and heat exchangers, but it offers relatively lower total utility costs of 91.03 $/hr and a reduced duty of 2.81 Gcal/hr. In contrast, although the low-pressure cooling process is simpler and cost-effective, it may encounter operational instability due to rapid pressure drops in the system. Environmental impact assessment revealed that the high-pressure cooling process is more environmentally friendly than the low-pressure cooling process, with an emission factor of 0.83 tCO2eq less than the low-pressure cooling process, calculated based on power usage. Consequently, the outcomes of this study provide relevant scenario and a database for green ammonia synthesis process adaptable to various process conditions.

본 연구에서는 이산화탄소를 배출하지 않고 수소를 운반할 수 있는 그린 암모니아 공정의 효율적인 설계를 위해 암모니아 액화 시나리오를 다르게 설계하고 이에 대한 경제성 및 환경 영향도 평가를 수행하였다. 순도 99.9 mol%의 148 kmol/hr 액화 암모니아를 생산물로 얻는 것을 목표로 설정하였고 후처리 단계에서 냉각단계 전 기-액분리를 통해 일정량의 액화 암모니아를 분리하고 고압에서 냉각하는 고압 냉각 공정과 기-액분리 과정 없이 바로 감압 후 냉각하여 기-액분리를 시켜 최종생산물을 얻는 저압 냉각 공정의 두 가지 케이스를 설정했다. 이에 대한 타당성 평가를 위해 Aspen Plus를 활용한 시뮬레이션을 수행하였다. 고압 냉각 공정은 많은 기-액분리 공정과 열교환기를 사용하여 초기장치 비용이 부담되지만 상대적으로 총 유틸리티 비용이 91.03 $/hr, duty가 2.81 Gcal/hr 낮아 유지비용이 적게 든다. 저압 냉각 공정은 초기 장치 비용이 낮고 운전이 용이하지만 급격한 압력 강하로 운전이 불안정한 것을 확인 하였다. 환경 영향도 평가 결과 고압 냉각 공정이 저압 냉각 공정보다 전력 사용량을 기준으로 산출한 이산화탄소 환산톤 배출 계수가 0.83 tCO2eq 더 낮아 환경친화적 임을 확인할 수 있었다. 본 연구 결과를 통해 향후 그린 암모니아 합성 공정에서 여러 상황에 적절한 설계안을 도출할 수 있는 데이터베이스를 확보할 수 있다.

Keywords

Acknowledgement

본 연구는 전남대학교 화학물질 안전관리 특성화대학원((사)한국화학물질관리협회) 연구비 지원으로 수행되었으며, 지원에 감사를 드립니다.

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