关键词: 生物质, 燃烧, 氯化钾, 磷酸二氢铵, 脱除

Abstract: Reduction of gaseous KCl producing in biomass combustion can help eliminate corrosion and ash deposition on the heating surface. Reaction characteristics of gaseous KCl and ammonium dihydrogen phosphate (ADP) are studied by using chemical thermal equilibrium analysis,including the effect of temperature and stoichiometric ratio. The simulation results show that gaseous KCl can be effectively transformed into K₂HPO₄ in a temperature range of 700—950℃. The reaction products obtained in the experiment using drop tube furnace system are analyzed by X-ray diffraction to examine the effects of mole ratio of P/K (α), residence time and temperature on KCl removal by ADP. The experimental results show that prolonging reaction time and increasing P/K mole ratio can promote conversion of gaseous KCl. At the experimental conditions: the temperature range of 700—1000℃, mole ratio of P/K of 1, residence time of 3 s, there is no KCl in the products (not detected by XRD). That means that KCl has be effectively transformed into dipotassium hydrogen phosphate (K₂HPO₄), potassium dihydrogen phosphate (KH₂PO₄), potassium metaphosphate[(KPO₃)_n], potassium pyrophosphate (K₄P₂O₇), potassium ammonium phosphate, potassium-ammonium dihydrogen phosphate etc. These results will be helpful for further study removing gaseous alkali metal ions by ammonium dihydrogen phosphate.

Key words: biomass, combustion, KCl, ammonium dihydrogen phosphate, removal