Integrating hydrogen liquefaction with steam methane reforming and CO2 liquefaction processes using techno-economic perspectives

초록

The increasing demand for liquid hydrogen as an environmentally friendly energy source necessitates developing an effective hydrogen liquefaction process. In this study, hydrogen production (steam methane reforming), hydrogen liquefaction, and CO2 liquefaction processes were successfully integrated by conducting several parametric studies involving three small-scale models and six scaled-up models. The enhanced liquefaction process included a modified Claude cycle that reduced the specific energy consumption to 6.15 kWh/kgLH(2), 47% lower than that of a reference process. Three different refrigerants (nitrogen, liquified natural gas, and hydrogen) were utilized in the integrated process, and an interactive genetic algorithm-based multi-objective optimization model was developed using the MATLAB-Aspen HYSYS interface to minimize the energy consumption and CO2 generation. In addition, a hybrid non-isothermal ortho-para hydrogen cooling heat exchanger was designed by performing an H-2 specific heat correction to enhance the robustness of the developed model. Techno-economic analysis of the designed process indicated that the integrated system considerably improved the main economic indicators (Levelized cost of hydrogen) and environmental friendliness of the hydrogen production process by approximately 51% and 95%, respectively. Moreover, CO2 liquefaction was performed most efficiently at a pressure of 120 bar with a reduced overall process cost. In addition, the LOCH (Levelized cost of hydrogen) of all the design integrated processes is less than $3/kg in market accessibility compared to the reference process. The sensitivity analysis results conducted by varying the costs of refrigerants, power (electricity), the selling price of liquid hydrogen, and carbon price revealed that the proposed integrated process had a higher application po-tential than other commonly used processes. In particular, under conditions of 45 tonne/day or more of carbon prices, the integrated process is environmentally and economically advantageous over the CO2 emission process with a reduced PBP of at least 10%.

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