350MW supercritical variable pressure operation coal burning boiler

The invention provides a 350MW supercritical variable pressure operation coal burning boiler. The boil is a direct-current boiler with single medium reheat and supercritical variable pressure operation and comprises a single hearth and a chimney flue; the lower part of the hearth is a spiral tube coil water wall structure of a rifled pipe; the water walls at the middle part and the lower part of the hearth adopt a spiral tube coil; the water wall at the upper part of the heart adopts an ascending vertical pipe platen in sequence; the water walls at the middle part and the lower part of the hearth are connected with each other by a transitional header tank; a rotary air preheater is arranged at the lower part of the boiler; a flue gas temperature adjusting baffle is arranged in the chimneyflue above the air preheater; an economizer is arranged above the flue gas temperature adjusting baffle; a low temperature reheater and a low temperature superheater are respectively arranged above the economizer; a low NOX coal dust combustor is arranged at the lower part of the hearth; and burnaway air is arranged above the low NOX coal dust combustor. The invention provides a boiler which has single hearth, balances ventilation, discharges slag in solid state, has entire steel frame structure, and can solves the problem that the previous constant pressure operation type boiler is unmatchedwith parameters of a stream turbine.