3 _ Pass_ Internal_Furnace_Packaged_Steam_Boilers Description: Intech (3 passes Internal Furnace Packaged Type Boiler) Boiler is the conventional three pass smoke-tube design coal / wood fired steam boiler having the internal furnace. This packaged Type Boiler comes in dry back , semi-wet back and fully wet-back options and is most suitable for manual firing of Solid Fuel likes coal, wood or briquettes . The furnace is totally submerged in water and the grate bars are fixed inside the furnace. The fuel of Packaged type Boilers is fired on the grate and the flue gases travel inside the smoke tubes of a second and third pass. A Water pre-heater may be provided of shell and tube design to enhance the efficiency of the systems by recovering waste heat from flue gases going ...