Thermodynamic and economic analysis of a new methanol steam reforming system integrated with CO2 heat pump and cryogenic separation system

A novel design has been developed to optimize the performance of the methanol steam reforming (MSR) system by integration with a CO2 heat pump (HP) and a cryogenic separation system. In the integrated system, the cryogenic separation system separates most of the CO2 from the MSR byproducts in liquid phase and the rest chemical energy of CO is recycled to MSR after combustion. Besides, the CO2 HP system organically connects the MSR process and the cryogenic separation system, which is capable to absorb the waste energy from MSR and also provides cryogenic energy to cryogenic separation system and mid-temperature heat to MSR preheating process. By such incorporation, the waste heat and the energy of CO can be fully utilized and the CO2 from MSR can be exported in liquid phase as a secondary product. Based on a 20,000 ton/year MSR plant, the energy and exergy analyses reveal that the energy and exergy efficiency are promoted by 5.57% and 5.15%, respectively. Besides, the profit of the integrated design is 139.6 M$ higher than that of the conventional system over the lifespan. Furthermore, sensitivity evaluation shows that the optimal reaction temperature is approximately 250 °C and the higher reaction pressure is favorable.