It is the Ⅱ-arrangement,free-circulation,single-cylinder,water-tube boiler.Combustion unit is the clockwise scaled coal-leakage prevention grate or horizontal-beam grate. There are suspension water screens around the hearth.Convection superheater is mounted in the horizontal flue and coal economizer and pre-heater in the tail flue.Wide range of coals is applicable.Boiler features sensitive adjustment,stable operation under 30% load full load,compact size and simple operation.