W-shaped flame boiler

The utility model relates to a W-shaped flame boiler which comprises a burner, a coal supplying system, a coal pulverizing system and a hearth, wherein the burner is used for providing primary air powder flow for the hearth, the coal pulverizing system is used for grinding coal provided by the coal supplying system and providing manufactured pulverized coal for the burner, and the coal supplying system is used for providing coal needed by the coal pulverizing system; and the W-shaped flame boiler is characterized in that at least one part of the burner is designed to be an internal combustion type burner used for ignition and stable combustion for the hearth, and the rest of the burner is designed to be an external combustion type burner; furthermore, the coal supplying system of the boiler comprises at least two parts, one part of the coal supplying system is used for providing coal needed by the coal pulverizing system first and then the internal combustion type burner, the other part of the coal supplying system is used for providing coal needed by the coal pulverizing system first and then the external combustion type burner. By using the W-shaped flame boiler, a great deal of fuel oil consumed during the starting, stopping and underload stably-burning processes of the traditional W-shaped flame boiler can be saved.