WATER-TUBE BOILER Russian patent published in 1999 - IPC

FIELD: heating systems. SUBSTANCE: boiler has water supply and discharge headers located above parallel tube bundles; dispensing tubes are laid coaxially inside uptake blind tubes; multisectional (multipassage) gas duct is also provided; each passage of gas duct is equipped with controllable dampers on one of respective sides over periphery of heated tubes; dampers are used for parallel and/or series connection of respective passages with furnace chamber. Load of boiler may be increased by two times with fan in operation and by several times during operation by chimney effect which is achieved through change of damper position. EFFECT: increased productivity; extended range of effective operation; reduction of thermal stresses; ease in cleaning and maintenance. 4 dwg