Combined cycles allow the most efficient utilisation of fuel energy for power generation and their design allows easy CO2 concentration and subsequent removal.
The overall objective of the present project is to explore the use of CO2, Steam and Argon mixtures as working agent in power cycles, and as gasification agent in coal/lignite gasification. The incentive for the use of such mixtures is the possibility to capture CO2 in a way which is believed to be competitive with other options such as CO2 recovery from stacks, fuel reforming or application of the shift reaction.
The use of semi-closed cycles running on CO2 rather than on steam or gas is not new, but it never reached any realisation phase. This is mainly due to i) the cost of separating oxygen, ii) the need for specially developed oxyfuel burners and gasifiers and iii) the need for specially designed turbo machines. The actual CO2 mitigation problem is however a strong incentive to reexamine the idea of the CO2 cycle, since a CO2-rich excess gas can easily be captured.
The present project analyses Combined, Steam injected (STIG) and Evaporative gas turbine cycles (HAT) in which Nitrogen is replaced by CO2 in a semi-closed cycle, and compares these options with the other potential routes such as the CO2 capture from stacks. Both direct firing (natural gas) and gasification (peat/coal) are considered.
Different cycle lay outs are proposed and analyzed for efficiency and techno-economical feasibility. Adapted oxyfuel burners are designed and tested on a 100 kWth scale. The adaptations required for CO2 gas turbines are assessed. Thermogravimetric analysis of coal/lignite gasification in different CO2/steam/argon mixtures are performed. Fluidized bed gasification in such mixtures is realized on lab scale. Problems of gas cleaning and CO2 purification are analyzed.
Funding SchemeCSC - Cost-sharing contracts
MK43 0AL Cranfield - Bedfordshire
100 44 Stockholm