Investigation on Effect of Phosphorus and Calcium on Ash Transformation and Agglomeration Behavior of Inorganic Potassium Salts in Biomass Using Coal Fly Ash as Additive during Gasification

Abstract

How the two major inorganic elements of biomass, calcium (Ca) and phosphorus (P), affect the transformation of ash and the agglomeration behavior of several common inorganic potassium (K) salts in biomass using coal fly ash as the additive was investigated under a steam gasification atmosphere in a lab-scale fixed-bed reactor. For KCl-loaded pine wood, the addition of calcite reduces the generation of KAlSiO₄ in ash while decreasing the presence of agglomerates coated with a K-silicate layer. In contrast, the contrary can be found for K₂CO₃-loaded and K₂SO₄-loaded pine wood. With the addition of KH₂PO₄ to K₂CO₃-loaded, K₂SO₄-loaded, and KCl-loaded pine wood, the ash is still dominant with KAlSiO₄. However, the presence of both calcite and KH₂PO₄ significantly inhibits the generation of silica sand particles coated with K-silicate for K₂CO₃-loaded, K₂SO₄-loaded, and KCl-loaded pine wood, thus mitigating bed agglomeration.