Process design and comprehensive analysis of CO2 liquefaction followed by carbon capture from steam methane reforming

Abstract

Hydrogen (H2) is widely utilized as a reactant for various materials and its demand is predicted to be grown further to utilize it as an energy source in the future. However, most of H2 is produced through steam methane reforming which emits a huge CO2. To address this, blue-H2, H2 production incorporating CO2 capture, has been proposed and evaluated considering the process system engineering aspects for its practical assessment, and captured CO2 is subsequently liquefied to enable efficient transportation and storage for high volumetric density of CO2. Therefore, this study conducts case study on the integrated CO2 capture-liquefaction process using various single and mixed-refrigerants to quantify energy consumption, and further optimize the process to improve energy efficiency. As a result, process models containing mixed-refrigerants show superior performance than the single-refrigerant cases with savings in specific energy demand of 3.58-4.54 %. Moreover, economic and environmental feasibilities were assessed. Mixed-refrigerant based integrated process showed promising figure of unit costs $26.62-26.68 kgLCO2-1 with 0.590-0.591 kgCO2-eq tonLCO2-1 while single refrigerant-based liquefaction processes emit less CO2 at a rate of 0.584 kgCO2-eq tonLCO2-1 with high total cost. Even if the trend of technical, economic, and environmental performance is different, the process based on the HFO-1234yf and isobutane mixed-refrigerant is determined as the best cases through analytic hierarchy process. Consequently, mixed-refrigerant-based integrated processes showed optimum solution as it has minimal sensitivity to the weight of each factor. The outcome of proposed research provides directions and critical consideration for the bulk removal and handling of CO2 in advancement of low-carbon technology. Also, it contributes to selecting favorable operating conditions and refrigerants for the development of energy-efficient integrated CO2 capture-liquefaction process.