Efficient hydrogen production through a novel methanol steam reforming system coupled with a two-stage heat pump and carbon capture: A thermodynamic and thermoeconomic study

A novel methanol steam reforming system is proposed to enhance the utilization efficiency of waste heat in hydrogen production from methanol. The system is integrated with a monoethanolamine carbon capture system and a two-stage compression heat pump system. In this integrated system, the high-temperature products of the methanol steam reforming system exchange heat with the feedstock and undergo gas-liquid separation. The low-temperature gas produced is pre-compressed and utilized for heating the feedstock. Furthermore, a two-stage heat pump uses the low-temperature lean solution from the carbon capture system as a heat source for feedstock heating. The analysis is conducted based on a hydrogen production capacity of 200 kg/h, revealing an enhanced energy and exergy efficiency of 5.4% and 3.5%, respectively, compared to the reference system. Additionally, waste heat utilization efficiency increases from 62.1% to 92.0%. The cost of hydrogen production is reduced from 3.089 $/kg to 2.054 $/kg, which is very close to the cost of hydrogen production without carbon capture. The exergoeconomic analysis indicates that the introduction of energy levels enhances the value of high-temperature steams, and the hydrogen production unit exergy of cost rate is elevated from 3.443 $/kWh to 4.411 $/kWh. The proposed system can readily harness low-grade waste heat and exhibits high thermodynamic efficiency, presenting a promising approach for low-energy-consumption methanol-hydrogen production.