Combustion of pulverized pre-dried brown coal: A chance for improving power plant efficiency and reducing CO{sub 2} emission
The high moisture and ash content in brown coal (lignite with low calorific value) requires drying of the fuel prior to combustion. In the brown-coal-fired power plants in operation today, this is done in a combined grinding and drying process. After the combustion process the evaporated water is released into the atmosphere together with the flue gas. In order to limit the resulting efficiency loss, various possibilities are being investigated which aim at generating electricity from lignite more efficiently by modifying the drying process and integrating it into the overall cycle. One option to improve efficiency is the development of the pre-dried brown-coal power plant with a separate low-exergy-loss drying system and a dry-brown-coal-fired steam boiler. Based on the idea of integrated drying and in connection with a pre-dried brown-coal-fired steam generator, efficiency improvements of up to 5 percentage points are possible compared to the drying method used today. An essential prerequisite for this type of brown-coal-fired power plant is the availability of a drying method that is technically and economically mature. In the new concept, low level heat from the power plant process is used to dry the raw brown coal, which results in improved fuel utilization. In addition to developing and testing methods for brown coal drying and coal water treatment, new technical solutions for the firing and steam generation process must be developed when operating power plants with pre-dried brown coal. This is basically due to the fact that the higher calorific values of pre-dried brown coal and the lack of vapor in the flue gas have an effect on the combustion, emission and slagging behavior.
- Research Organization:
- RWE Energie AG, Essen (DE)
- OSTI ID:
- 20082318
- Country of Publication:
- United States
- Language:
- English
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