Mapping the effects of potassium on fuel conversion in industrial-scale fluidized bed gasifiers and combustors
Journal article, 2021

Potassium (K) is a notorious villain among the ash components found in the biomass, being the cause of bed agglomeration and contributing to fouling and corrosion. At the same time, K is known to have catalytic properties towards fuel conversion in combustion and gasification environments. Olivine (MgFe silicate) used as gasifier bed material has a higher propensity to form catalytically active K species than traditional silica sand beds, which tend to react with K to form stable and inactive silicates. In a dual fluidized bed (DFB) gasifier, many of those catalytic effects are expected to be relevant, given that the bed material becomes naturally enriched with ash elements from the fuel. However, a comprehensive overview of how enrichment of the bed with alkali affects fuel conversion in both parts of the DFB system is lacking. In this work, the effects of ash-enriched olivine on fuel conversion in the gasification and combustion parts of the process are mapped. The work is based on a dedicated experimental campaign in a Chalmers DFB gasifier, wherein enrichment of the bed material with K is promoted by the addition of a reaction partner, i.e., sulfur, which ensures K retention in the bed in forms other than inactive silicates. The choice of sulfur is based on its affinity for K under combustion conditions. The addition of sulfur proved to be an efficient strategy for capturing catalytic K in olivine particles. In the gasification part, K-loaded olivine enhanced the char gasification rate, decreased the tar concentration, and promoted the WGS equilibrium. In the combustion part, K prevented full oxidation of CO, which could be mitigated by the addition of sulfur to the cyclone outlet.




Combustion emissions

Dual fluidized bed






Teresa Berdugo Vilches

Chalmers, Space, Earth and Environment, Energy Technology

Jelena Maric

Chalmers, Space, Earth and Environment, Energy Technology

Henrik Thunman

Chalmers, Space, Earth and Environment, Energy Technology

Martin Seemann

Chalmers, Space, Earth and Environment, Energy Technology


20734344 (eISSN)

Vol. 11 11 1380

Subject Categories

Chemical Process Engineering

Other Chemical Engineering




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