Biomethane and CO₂-Based Biorefinery: Process Concept and Operability Analysis

The climate crisis, along with the need to improve human living standards and preserve the environment, is driving the demand for processes that are sustainable in terms of emissions, heat demand, electricity sources, water usage, and food supply. Developing such processes requires renewable and sufficient raw materials, heat, power, and complex mass and heat integration schemes. In this context, a process for synthetic hydrocarbon production from biomethane with power cogeneration is proposed. Biomethane is used as a raw material for the process and for the power plant, while CO2 is fed to the process in similar mass proportions to biomethane. By this process, including steam methane reforming, reverse water–gas shift, and Fischer–Tropsch synthesis (FTS) reactions, it is possible to obtain 29.3 tons/h (1048 m3/day) of synthetic liquid fuels. The process is self-sufficient in terms of water and power, and it provides a considerable amount of excess heat for byproduct generation, showing itself as a promising alternative for sustainable fuel production. Operability analyses are performed for the first time in the literature on simulations of FTS plants to assess the effect of key process input variables on the simulation convergence and process output regions. A set of 26 inequality constraints that describe the feasible input region for the process is obtained, which can be used for future optimization. The proposed approach enhances the process understanding and represents an important step forward to allow hard-to-converge flowsheet optimizations of complex and highly integrated process models.