Carbon capture from advanced integrated gasification combined-cycle (IGCC) processes should outperform conventional coal combustion with subsequent CO2 separation in terms of efficiency and CO2 capture rates. This paper provides a thermodynamic assessment, using an exergy analysis of a syngas redox (SGR) process for generating electricity. The power island of the proposed process uses syngas produced by coal gasification and is then cleaned through a high-temperature gas desulfurization (HGD) process. Hematite (Fe2O3) is used as an oxygen carrier to oxidize the syngas. To achieve a closed-cycle operation, the reduced iron particles are first partially re-oxidized with steam and then fully re-oxidized with pressurized air. One advantage of this design is that the resulting hydrogen (using steam in the re-oxidation section) can be utilized within the same plant or be sold as a secondary product. In the proposed process, diluted hydrogen is combusted in a gas turbine. Heat integration is central to the design. Thus far, the SGR process and the HGD unit are not commercially availiable. To establish a benchmark, the rate of exergy destruction within the SGR process was compared to a coal-fed Shell gasification IGCC design with Selexol-based precombustion carbon capture. Some thermodynamic inefficiencies were found to shift from the gas turbine to the steam cycle and redox system, while the net efficiency remained almost the same. A process simulation was undertaken, using Aspen Plus and the engineering equation solver (EES).
Exergetic Assessment of a Syngas-Redox-Based IGCC Plant for Generating Electricity
Contributed by the Cycle Innovations Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received May 8, 2013; final manuscript received October 15, 2013; published online November 22, 2013. Assoc. Editor: Paolo Chiesa.
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Sorgenfrei, M., and Tsatsaronis, G. (November 22, 2013). "Exergetic Assessment of a Syngas-Redox-Based IGCC Plant for Generating Electricity." ASME. J. Eng. Gas Turbines Power. March 2014; 136(3): 031702. https://doi.org/10.1115/1.4025885
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