Modares Mechanical Engineering

Modares Mechanical Engineering

Techno-Economic Assessment of Sulfur Dioxide Recovery and Liquefaction from Sulfur Recovery Unit Flue Gases: A Gas Refinery Case Study

Document Type : Original Article

Authors
Mahdi Pourafshari Chenar 1
Ali Farzaneh 2
1 Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
2 Department of Energy Engineering, Faculty of Advanced Technologies, Quchan University of Technology, Quchan, Iran
10.48311/mme.2026.120210.83025
Abstract
Sulfur dioxide (SO₂) is one of the major pollutants emitted from industrial flue gases and its release is associated with significant environmental impacts. In this study, the technical and economic feasibility of SO₂ recovery and liquefaction from sulfur recovery unit flue gases of a gas refinery was investigated. The Cansolv process was selected owing to its high recovery efficiency, compatibility with sulfur recovery unit flue gases, and industrial maturity. The SO₂ recovery unit was designed based on licensor data, while the dehydration and liquefaction sections were designed using Aspen HYSYS V8.6. Economic assessment was conducted using the factorial method and discounted cash flow analysis. For the selected case study, an SO₂ recovery and liquefaction unit with a production capacity of 337,000 t/y and a product purity of 99.95 wt.% was designed. The total capital investment and annual production cost were estimated at USD 103.4 million and USD 31.3 million per year, respectively. At the design capacity and an SO₂ selling price of USD 400/t, the economic indicators including ROI, NR, NPW, and PBP were estimated at 57.9%, USD 45.5 million, USD 229.5 million, and 1.3 years, respectively. Moreover, the economic break-even production capacity was determined as 37,000 t/y, substantially lower than the nominal design capacity. The results indicate that SO₂ recovery and liquefaction, besides mitigating acidic pollutant emissions, can represent an economically attractive pathway for value-added product generation. Furthermore, environmental penalties, pollutant pricing policies, and green financing mechanisms could further enhance the economic attractiveness of such projects.
Keywords
Sulfur dioxide
Flue gas
SO₂ recovery
Techno-economic assessment
Gas refinery
Subjects
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Modares Mechanical Engineering
Volume 27, Issue 2
February 2027
Pages 103-114