The effect of green hydrogen feed rate variations on e-methanol synthesis by dynamic simulation

Abstract

Methanol is a promising fuel and important intermediate chemical in the transformation of renewable power to chemical products since it can be directly synthesized from captured CO₂ and electrolytic H₂. However, the intermittency of renewable power generation poses challenges to green methanol production process design and operation, necessitating high operational flexibility to facilitate coupling with intermittent renewable power. In this study, a green crude methanol (a mixture of methanol and water from methanol synthesis) production process was dynamically modeled. The results show that the minimum load of the model is 20 %, with maximum allowable ramping rates of 3.25 %/minute for ramp-down and 2.10 %/minute for ramp-up between full and minimum load. The introduction of a standby mode, in which a make-up H₂ stream is supplied when electrolytic H₂ is unavailable, allows continuous operation of the process at the minimum load. With the constructed control structure, the model demonstrates that the process can effectively handle continuous variations of electrolytic H₂ input.