Development of online method to characterize char loading in fluidized bed combustion

Antti Tourunen, Andriy Ivannikov, Jaakko Saastamoinen, Tommi Kärkkäinen, Heidi Nevalainen, Mykola Pechenizkiy

Research output: Contribution to journalArticleScientificpeer-review


One important characteristic of the burning process in a CFB boiler is the char load, for which we need to have a quantitative estimate. Direct measurement of char inventory from the commercial-scale fluidized bed boiler is difficult and time consuming due to sampling of solid material and chemical analysis in laboratory and it cannot be used to monitor the char inventory online. A method to determine char loading and its variation in fluidized bed combustion depending on process conditions was developed and validated with the laboratory-scale measurements. We found that the standard deviation of high-frequency fluctuations of the O2 concentration signals correlates to the char load. Char inventory depends on char residence time and reactivity which all are important parameters for process monitoring and control. The developed method which is based on analysis of vibration of flue gas oxygen concentration can be applied to combustion control system to estimate fuel reactivity in existing process conditions. Fuel reactivity is an important parameter in load changes, of CFB boilers. Especially, if feed forward control is used during the load change the description of combustion dynamics must be known. CFB boilers based on once-through steam cycle need feed forward controls in order to meet the requirements of power network.
Original languageEnglish
Pages (from-to)191-203
JournalInternational Journal of Materials Engineering and Technology
Issue number2
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed


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