Effect of Additives on Potassium Distribution during Rice Straw Combustion

In order to provide references and bases for solving slag, agglomeration and corrosion problems that occurred during straw combustion, experiments on combustion of pure pulverized rice straw and mixture of pulverized rice straw with additives were carried out in a pilot plant. The additives included CaO, Al₂(SO₄)₃18H₂O, CaSO₄, and (NH₄)H₂PO₄. Ion chromatography as well as XRD analysis have been conducted to measure the potassium content in gas and deposit, water-soluble potassium in bottom ash and phase of bottom ashes. The mechanism of additives on potassium distribution during rice straw combustion has been investigated in detail. The result shows that Al₂(SO₄)₃18H₂O, CaSO₄, and (NH₄)H₂PO₄ can make potassium in raw straw be fixed in components that have high melting points. CaO has not been directly involved in the reaction with alkali metals, but can react to other elements in the system, which enable potassium in the straw to be separated from bottom ash.