Utilization of blast furnace flue gas: Opportunities and challenges for polymeric membrane gas separation processes

- Concentration tuning function of membrane process for multicomponent mixtures.
- Combined CO2 capture and CO recovery is achievable.
- CO/N2 separation bottleneck for CO concentration.
- Vacuum operation more economical for moderate CO2 purity.
- Membrane cost dominates for vacuum operation.

New programs seeking to improve energy efficiency and reduce GHG emissions from the steelmaking industry are studying alternative uses for blast furnace gas such as the VALORCO project in France. One promising alternative is CO2 and CO utilization in which emissions are used for the production of valuable products, like industrial intermediates and fuels synthetized from CO or CO2 or both. A gas separation and concentration technology is necessary to recover industry emissions and produce gas stream(s) suitable for carbon utilization technologies. This paper describes the application of commercially available polymeric gas separation membranes to blast furnace gas. Data for two commercially available membranes, a H2 selective glassy polyimide membrane from UBE industries and a CO2 selective rubbery composite membrane from MTR Inc. along with a process economic modelling have been used for the calculation of product composition paths and associated costs depending on product purity and recovery. Relatively low separation costs, from 15 to 33 EUR/Ton separated CO2, seem promising for the use of membrane technology as a concentration tuning box prior to carbon utilization technologies, notably for mid to high CO2 purity requirements, and allow to simultaneously achieve CO2 capture and CO recovery.