A Parametric Investigation of Integrated Gasification Combined Cycles with Carbon Capture

摘要

IGCC (Integrated Gasification Combined Cycle) technology is being developed to enable electricity to be generated at high efficiency and low emissions. Continuous improvement is essential to make IGCC reliable and cost-effective. As environmental concerns over carbon emissions escalate, development of a practical carbon capture and storage (CCS) technology has become an important issue. Combining IGCC and CCS has become a promising technology to reduce the cost of CCS. This study investigates the pros and cons of different methods used to put together an approximately 250 MW IGCC plant with and without CCS by using the commercial software Thermoflow. Seven different IGCC plants have been designed with various parameters examined, including: oxygen-blown vs. air-blown, with/without integration, with/without CCS, sour vs. sweet water shift for carbon capture, and dry- vs. slurry-fed. This study is based on technologies that are commercially available or close to commercialization. The results show that (a) integration between the gas turbine and the air separation unit (ASU) can boost the cycle efficiency about 4.5% (1.6 percentage points); (b) dry-feeding increases the CO content, the syngas heating value (19%), and the efficiency about 11% (4.7 percentage points); (c) carbon capture reduces the power output by 2.7% and efficiency by 10% (or 4.5 percentage points) and the slurry-fed system takes a heavier toll on power output and efficiency than the dry-fed system; (d) air-blown systems do away with the ASU, resulting in syngas with a 50% lower heating value and a small reduction in efficiency, but harvesting savings on reduced capital, operating, and maintenance costs; (e) for CO_2, sweet water shift results in 5.5% (2 percentage points) higher cycle efficiency than sour shift.