Hydrogen production is critical to many modern chemical processes –ammonia synthesis, petroleum refining, direct reduction of iron, and more. Conventional approaches to hydrogen manufacture include steam methane reforming and autothermal reforming, which today account for the lion’s share of hydrogen generation. Without CO 2 capture, these processes emit about 8.7 kg of CO 2 for each kg of H 2 produced. In this study, a molten carbonate fuel cell system with CO 2 capture is proposed to retrofit the flue gas stream of an existing Steam Methane Reforming plant rated at 100,000 Nm 3 h − 1 of 99.5% pure H 2 . The thermodynamic analysis shows direct CO 2 emissions can be reduced by more than 95%, to 0.4 to 0.5 kg CO 2 /kg H 2 , while producing 17% more hydrogen (with an increase in natural gas input of approximately 37%). Because of the additional power and hydrogen generation of the carbonate fuel cell, the efficiency debit associated with CO 2 capture is quite small, reducing the SMR efficiency from 76.6% without capture to 75.6% with capture. In comparison, the use of standard amine technology for CO 2 capture reduces the efficiency below 70%. This demonstrates the synergistic nature of the carbonate fuel cells, which can reform natural gas to H 2 while simultaneously capturing CO 2 from the SMR flue gas and producing electricity, giving rise to a total system with very low emissions yet high efficiency.

Low-carbon hydrogen via integration of steam methane reforming with molten carbonate fuel cells at low fuel utilization

Consonni, Stefano;
2021

Abstract

Hydrogen production is critical to many modern chemical processes –ammonia synthesis, petroleum refining, direct reduction of iron, and more. Conventional approaches to hydrogen manufacture include steam methane reforming and autothermal reforming, which today account for the lion’s share of hydrogen generation. Without CO 2 capture, these processes emit about 8.7 kg of CO 2 for each kg of H 2 produced. In this study, a molten carbonate fuel cell system with CO 2 capture is proposed to retrofit the flue gas stream of an existing Steam Methane Reforming plant rated at 100,000 Nm 3 h − 1 of 99.5% pure H 2 . The thermodynamic analysis shows direct CO 2 emissions can be reduced by more than 95%, to 0.4 to 0.5 kg CO 2 /kg H 2 , while producing 17% more hydrogen (with an increase in natural gas input of approximately 37%). Because of the additional power and hydrogen generation of the carbonate fuel cell, the efficiency debit associated with CO 2 capture is quite small, reducing the SMR efficiency from 76.6% without capture to 75.6% with capture. In comparison, the use of standard amine technology for CO 2 capture reduces the efficiency below 70%. This demonstrates the synergistic nature of the carbonate fuel cells, which can reform natural gas to H 2 while simultaneously capturing CO 2 from the SMR flue gas and producing electricity, giving rise to a total system with very low emissions yet high efficiency.
Molten carbonate fuel cell
Steam methane reforming
Retrofit
Carbon capture and storage
Hydrogen
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1208460
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