(16d) Synthesis, Design and Thermodynamic Analysis of Hybrid Processes Gasifying Biomass and Smelting Iron

Emerging research has revealed tremendous benefits in hybridizing the processes of iron ore reduction and biomass gasification. The iron ore acts as both an oxidant and a catalyst for the biomass gasification, while the biomass in turn replaces coking coal as the reducing agent for iron ore. The result is a carbon neutral iron ore reduction process co-producing synthesis gas.

This research presents detailed thermodynamic analysis of this system of chemical reactions to develop process targets and offer a starting point for design and optimization, as well as a basis for economic evaluation. Also presented is a sensitivity analysis to determine the effect of silica content on process performance.

It has been found that there is an inverse linear proportionality between iron reduction capacity and synthesis gas production and that the best economic performance under present market conditions is achieved by maximizing iron smelting and producing little or no synthesis gas.

However, the capacity for co-production allows for the operational flexibility to operate at maximum capacity during periods of reduced iron throughput, by transitioning to the production of synthesis gas. Once an iron deposit is depleted, a smelter capable of biomass gasification need not be scrapped; it can instead transition to full-time fuel production. In this way, iron/synthesis gas co-production can be thought of as a stepping stone to long-term renewable fuel production.