CASCADE AIR SUPPLY SYSTEM FOR FIRST PREHEATING SECTION OF GRATE AND AIR SUPPLY METHOD

The present invention relates to a cascade air supply system for a first preheating section of a grate and an air supply method. The system comprises a grate, wherein the grate is sequentially divided into a forced air drying section, an exhaust drying section, a first preheating section and a second preheating section in a material flow direction. The system is characterized by further comprising a two-cooling-section waste gas pipeline, combustion chambers and a regulating valve, wherein a two-cooling-section waste gas main pipe is connected to an upper cover of the first preheating section of the grate by means of waste gas branch pipes, the regulating valve is provided on a waste gas branch pipe I, a combustion chamber I is provided on a waste gas branch pipe II, a combustion chamber II is provided on a waste gas branch pipe III, a combustion chamber III is provided on a waste gas branch pipe IV, and a temperature measurement device I, a temperature measurement device II, a temperature measurement device