A novel cryogenic-thermochemical approach for clean hydrogen production from industrial flue gas streams with carbon capture and storage

The present work aims to develop a novel integrated energy system for clean hydrogen production from the industrial flue gas stream. The particular system incorporates a cryogenic distillation unit for H₂S and CO₂ separation and a thermochemical cycle for hydrogen production. The industrial flue gaseous mixture is considered a major feedstock for the present system. H₂S is retrieved from the waste gaseous stream and fed to the two-step sulfur looping thermochemical cycle to perform clean hydrogen production. In this way, clean hydrogen production, elemental sulfur production, carbon capture, and storage are achieved. The entire integrated energy system is simulated in the Aspen Plus process simulator and is investigated thermodynamically in terms of energy and exergy performances. Various parametric studies are conducted to assess the significance of operating parameters on the system performance. The H₂S and CO₂ removal rates from the waste feed stream are found to be 85.55 % and 84.62 %. The H₂S conversion into hydrogen is determined to be 66.67 %. The energy and exergy efficiencies of the two-step thermochemical cycle are found to be 53.93 % and 23.69 %, respectively. The parametric studies show that the hydrogen production rates of 3.63 kmol/h, 2.46 kmol/h, and 1.78 kmol/h are achieved at sulfurization temperatures of 200 °C, 300 °C, and 500 °C, respectively. The study further concludes that 44.60 % of the total input exergy is lost due to the presence of irreversibilities within the system. The overall energy and exergy efficiencies of the integrated energy system are found to be 82.99 % and 55.39 %, respectively.