Thermodynamic and economic analysis of a synthetic fuel production plant via CO2 hydrogenation using waste heat from an iron-steel facility

Abstract

This study aims to investigate thermodynamic and economic feasibility of utilizing medium temperature waste heat from an iron-steel facility to produce synthetic fuel via captured CO2 hydrogeneration. First, waste heat from reheating and blast furnace of an iron-steel facility is used as heat resource for a regenerative Kalina cycle (KC) to generate electrical power and to heat the reboiler of an amine-based Carbon capture plant (CCP). Later, generated electricity from the KC is used for the PEM electrolyser and other power consuming devices through the plant. Generated hydrogen and captured CO2 are utilized in the methanol production plant (MPP). KC showed highest efficiency at a maximum temperature of 488 K with an ammonia fraction of 65% while the optimal current density of the PEM electrolyser is 2.2 kA/m2. Under optimal conditions, plant fuel production efficiency reached up to 19% with a methanol cost of $532 ton-1 for a daily methanol capacity of 3.69 tons. Present plant is competitive to those of other clean synthetic fuel production facilities. Such configurations can be scaled up for large amounts of carbon capture and utilization.