Potassium capture by coal fly ash K2CO3, KCl and K2SO4

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The potassium capture behavior of two coal fly ashes at well-controlled suspension-fired conditions was investigated through entrained flow reactor (EFR) experiments and chemical equilibrium calculations. The impact of local reaction conditions, i.e., the type of K-salts (K2CO3, KCl or K2SO4), K-concentration in flue gas (molar K/(Al + Si) ratio in reactants), reaction temperature, and coal ash type on the reaction was studied. The results show that the K-capture level of coal fly ash at a K-concentration of 500 ppmv (K/(Si + Al) = 0.481) was considerably lower than the equilibrium data as well as the measured K-capture level of kaolin. However, at 50 ppmv K (with a molar K/(Si + Al) ration of 0.048), no obvious difference between kaolin and coal fly ash was observed in this work. Comparison of results for different K-species showed that coal fly ash captured KOH and K2CO3 more effectively than KCl and K2SO4. Additionally, a coal fly ash with higher content of Si and a lower melting point captured KCl more effectively than the reference coal fly ash.

Original languageEnglish
Article number106115
JournalFuel Processing Technology
Number of pages11
Publication statusPublished - 2019


  • Additive
  • Biomass combustion
  • Coal fly ash
  • K2CO3
  • KCl
  • Potassium capture

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