To miniaturize heat recovery equipment by reducing the burning out time of pulverized coal.

A burner is formed by arranging at least a pair of heat exchangers 16 provided with thermal storage bodies 16b made of honeycomb ceramic on the furnace walls 1a of combustion furnaces 1, connecting combustion air supply and combustion gas exhaust pipes 15 on the upstream side of these heat exchangers 16, and connecting combustion air and combustion gas exhaust paths 3A surrounding the burner inner cylinder 3B on the down stream side of the heat exchangers 16. A pulverized coal supply pipe 14 is connected to the burner inner cylinder 3B, a combustion air supply pipe 15a and a combustion gas exhaust pipe 15b are connected to the other end of the combustion air supply and combustion gas exhaust pipe 15b through a four-way valve 17, combustion air 11 heated through the heat exchanger 16 and pulverized coal 19 from the burner inner cylinder 3B are fed to one burner 3a and burned by switching the four-way valve 17 periodically, and the heat exchanger 16 is heated and the combustion gas 13 is cooled by feeding the combustion gas 13 reversely flown from the other burner 3b to the heat exchanger 16 while switching between the one burner 3a and the other burner 3b.