Firing of coal and biomass and their mixtures in 50 kW and 12 MW circulating fluidized beds - Phenomenon study and comparison of scales

H. Nevalainen*, M. Jegoroff, J. Saastamoinen, A. Tourunen, T. Jäntti, A. Kettunen, F. Johnsson, F. Niklasson

*Corresponding author for this work

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The combustion dynamics of coal, wood chips and their mixture is investigated. Load change capability and the effect of the individual control variables, for example the mixture ratio of different fuels, on pilot-scale CFB boiler dynamics were also studied. Disturbances in fuel feeding cause fluctuations in the flue gas concentrations. Changes in the heating value are possible due to varying moisture content of the fuel. Both these disturbances affect the instantaneous firing rate in a boiler. Also the characteristics of the fuels have to be taken into consideration when designing boiler control systems. When co-firing two fuels with clearly distinct combustion characteristics, direct assumptions based on each fuel's characteristics cannot be made about combustion behaviour of their mixture. Combustion experiments with coal and wood chips and their co-firing were carried out in a pilot-scale CFB reactor (VTT) and a large-scale CFB boiler (Chalmers). A comparison of the combustion in the two different size reactors, provides information about scaling. The combustion responses due to changes in the fuel feeding of the two circulating fluidized beds are analyzed by a dynamic model.

Original languageEnglish
Pages (from-to)2043-2051
Number of pages9
JournalFuel
Volume86
Issue number14 SPEC. ISS.
DOIs
Publication statusPublished - Sep 2007
Externally publishedYes

Keywords

  • CFBC
  • Dynamics
  • Fuel mixtures

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