**7. Findings**

The most important findings from the research can be summarized as follows:


Co-Combustion of Coal and Alternative Fuels 89

with the technical parameters until they started operation. The first operation hours of the most of these boilers were affected by the typical characteristics of Czech coal. Highly abrasive ash matter, high humidity, clay impurity of the fuel and higher content of other elements in the raw fuel (stone, wood, metal) made it necessary to modify fuel feed channels, crushers, separating plants and fuel intake to fluid channels. Many times before, these problems resulted in total unit reconstruction or even replacement. Frequent fuel supply discharges led to reduction of durability of heavy linings of the combustion chamber, especially cyclone bricking and chutes under the cyclones. Some problems were caused by ash extraction from fluidized layer, its cooling down, granulometrics finishing and further manipulation. Other problems occured in sintering fluidized particles when combustion temperatures were well below 900 oC. In spite of this mass sintering happens in various parts of the boiler. Last but not least, there is a trend to reduce desulphurization costs if the molar ratio Ca/S is in the range of / from 2.5 to 3, which means higher operation

A quite new area of fluidized bed boilers is the combined combustion of coal and alternative fuels or the co-combustion of assorted fuels from renewable sources. Despite some slowdown in the expansion of activities in energetics, there are further projects in the area of applied research focused on operation process optimization, efficiency improvements and operation costs minimization. These are the areas where the information obtained from

The author would like to express their acknowledgements to the National Program of Research *ENET* – energy units for utilization of non-traditional energy sources

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costs compared to wet tailings.

**9. Acknowledgments** 

**10. References** 

measurement results in various boiler types can be used.

cz.1.05/2.1.00/03.0069 for the financial support of this work.

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Earthscan, ISBN 978-1-84407-249-1, London, UK

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comparable to those of sewage sludge, wood, peat and coal. The K2O content of the fuel ashes on their melting points is well demonstrated.

