Calculated results conform to the expected boiler life of 30 years,and the method can be used for the strength and life calculation of the boiler tee at elevated temperature.

The application of ratio integration and calculus regulation in furnace temperature;

The control result of the rotary reheating furnace is proved well in mathematic model optimizing control system,through on-line piecewise furnace temperature optimization based on the optimal heating-up curve of steel tube.

In order to ensure smooth conditions in furnace and achieve fine smelting indices, scientific operating methods and policy should be adopted, such as controlling furnace temperature and slag basicity, improving blast momentum, strengthening chargeable materials and using high quality coke, etc.