Self-anticorrosion for the combustion tower of heat recovered thermal process phosphoric acid production

When a combustion boiler is used to recover heat released from yellow phosphorus combustion for phosphoric acid production, serious corrosion of the inner wall of the combustion tower caused by high temperature acid substances becomes a very critical problem. Based on pilot experiments, we found that a layer of anti-corrosion protective coating can be generated and adhered on the inner wall of the combustion tower by controlling the process parameters, including RH2O - P4O10(the molar ratio of moisture of feeding air to the phosphorus pentoxide produced from reaction) and TA (the temperature of the outlet gas from the combustion tower). This coating can prevent high temperature acid gas from directly contacting the inner wall of the combustion tower, so that the tower can be effectively protected from corrosion. This work innovatively realizes the self-anticorrosion of the combustion tower through controlling the reaction conditions. The main composition and preliminarily conjectured molecular structure of this costing was firstly identified by the analyzing its chemical components, physical and chemical properties, crystal form, and other detection data. Finally, operating conditions for stabilizing this coating were proposed and verified based on an industrialized production process.