Modeling of Ultra Superheated Steam Gasification in Integrated Gasification Combined Cycle Power Plant With Carbon Dioxide Capture

Abstract

Integrated Gasification Combined Cycle (IGCC) is believed to be one of the most promising technologies to offer electricity and other de-carbon fuels with carbon capture requirement as well as to meet other emission regulations at a relatively low cost. As one of the most important parts, different gasification technologies can greatly influence the performance of the system. This paper develops a model to examine the feasibilities and advantages of using Ultra Superheated Steam (USS) gasification technology in IGCC power plant with carbon dioxide capture and storage (CCS). USS gasification technology converts coal into syngas by the endothermic steam reforming reaction, and the heat required for this reaction is provided by the sensible heat in the ultra superheated steam. A burner utilizes synthetic air (21% O2 and 79% H2O) to burn fuel gas to produce the USS flame for the gasification process. The syngas generated from USS gasification has a higher hydrogen fraction (more than 50%) then other gasification processes. This high ratio of hydrogen is considered to be desired for a “capture-ready” IGCC plant. After gas cleanup and water gas shift reaction, the syngas goes to the Selexol process for carbon dioxide removal. Detailed calculations and analysis are performed to test the performance of USS gasification technology used in IGCC generation systems. Final results such as net output, efficiency penalty for CO2 capture part, and net thermal efficiency are calculated and compared when three different coal types are used. This paper uses published data of USS gasification from previous research at the University of North Dakota. The model also tries to treat the IGCC with carbon dioxide capture system as a whole thermal system, the superheated steam used in USS gasification can be provided by extracting steam from the lower pressure turbine in the Rankine Cycle. The model will make reasonable use of various waste energies and steams for both mechanical and chemical processes to improve the performance of the plant, and incorporate CO2 capture system into the design concept of the power plant.