Boiler glossary

Boiler glossary B


BABCOCK & WILCOX BOILER -- A water tube boiler consisting of a horizontal drum from which is suspended a pair of headers carrying between them an inclined bank of straight tubes.
BACKWASH -- A stage in the regeneration cycle of a softener or other ion-exchanger equipment during which water-flow through the unit is directed upwards through the resin bed. This is done to clean and reclassify the bed following exhaustion.
BAFFLE -- A plate used to prevent the movement of gases or liquids in the direction that it would normally follow, and to direct it into the desired path.
BALANCED DRAUGHT -- A system of air-supply to a boiler furnace, in which one fan forces air through the grate, while a second, situated in the uptake, exhausts the flue gas. The pressure in the furnace is thus kept atmospheric, i.e., balanced.
BAROMETRIC DRAFT CONTROL -- A damper, mounted on the vent stack of a furnace or boiler that maintains the draft at a constant level.
BARRING GEAR -- Arrangement for moving the engine by manpower, used to turn the engine slowly for adjustment or inspection.
BARRING MOTOR -- Motor connected to the barring gear in large engines.
BELLEVILLE BOILER -- An old water tube boiler.
BENSON BOILER -- A high-pressure boiler of the once-through type in which water is pumped through the successive elements of the heating surface, fired by oil or gas.
BENT-TUBE-BOILERS -- Bent-tube design characterized by tubes entering the steam and water drums at right angles to the drum surface. Advantages: more tubes in any given area, ease of rolling and expanding tubes in tube sheets, accelerated circulation and greater steaming capacities.
BEVEL GEAR -- A system of toothed wheels connecting shafts whose axes are at an angel to one other but in the same plane.
BIMETALLIC ELEMENT -- A device consisting of two different metals fastened together which bends in a certain direction depending on the temperature. Commonly used in thermostats.
BILGES -- The lowest part of the interior of a vessel's hull where any internal water collects.
BLAST PIPE -- The exhaust steam pipe in the smoke box of an locomotive-boiler, which terminals in a nozzle to provide draught by entraining the flue gases in the steam-jet and exhausting them through the chimney.
BLOWDOWN VALVE -- Blow-down valves are fitted on the mud drum and should the testing of boiler water indicate the need for blowing down, the blow-down valves should be opened wide quickly for successive short periods in order to remove any deposit and to prevent the choking of the valve or cutting the valve plug or zeat. Boilers above 20 bar, at the superheater outlet are fitted with double blow-down valves and the valve attached to the boiler must be treated as a shut-off valve and is to be full open during blowing.
IMPORTANT. When boilers have water cooled furnace walls, the drain valves on the water wall headers must never be opened when the boilers are steaming.
BLOWER -- A fan used to force air under pressure.
BLOW-OFF VALVE -- Also called bottom blowdown valve.
BLUE FLAME BURNER -- Some of the hot gases from the flame are recirculated back to the inlet where they mix with and heat the combustion air.
BOILER CAPACITY -- The weight of steam, usually expressed in kg or lb/hr, which a boiler can evaporate when steaming at full load output.
BOILER COMPOSITIONS -- Chemicals introduced into boiler feed-water to inhibit scale-formation and corrosion, or to prevent priming or foaming. Examples are sodium compounds (such as soda ash), organic matter, and barium compounds.
BOILER CRADLES -- The wrought-iron saddles or standards that support cylindrical boilers of the Scotch marine type. Also called Keelson.
BOILER CROWN -- The upper rounded plates of a boiler of the shell type.
BOILER FEED WATER PUMP -- Two pumps are normally installed, one for operation and the other for stand-by purpose. The stand-by pump has to start upon low pressure in the feed water line to the boiler.
BOILER HEATING SURFACE -- The area of the heat transmitting surfaces in contact with the water or the steam in the boiler on one side and the fire or hot gases on the other.
BOILER HORSEPOWER -- One boiler horse power is equal to an evaporation rate of 34.5 pounds (15.649kg) of water per hour from and at 212°F (100°C).
That is 33471.403...BTU/h (9.8095...kW).
Boilers in ships were not customarily rated in boiler horsepower.
BOILER SCALE -- A hard coating, chiefly calcium sulphate, deposed on the surfaces of plates and tubes in contact with water in a steam-boiler. If excessive, it leads to overheating of the metal and ultimate failure.
BOILER SHELL -- The outer cylindrical portion of a pressure vessel.
BOILING OUT -- The boiling of highly alkaline water in boiler pressure parts for the removal of oils, greases, etc.
BOILERS -- Boilers are usually classified as water-tube boilers or fire-tube boilers. In the fire-tube boiler the combustion occurs in heavy duty tubes and the flue gases carries off through smoke tubes. In the water-tubes boiler the water flows in tubes surrounded by the combustion gases.
BOTTOM BLOW VALVE -- A valve located near the bottom of the boiler for the purpose of blowing off the mud and sediment.
BRACING -- The stay rods, stay bolts and stay tubes used in supporting the flat surfaces in a boiler.
BRIDGEWALL -- A wall in a furnace over which the products of combustion pass.
BTU -- British Thermal Unit, the amount of energy required to raise one pound of water by one degree Fahrenheit.
BUCK PLATES -- Steel plates used to tie together with tie-rods the brickwork of a furnace.
BUCKSTAY -- A structural member placed against a furnace or boiler wall to restrain the motion of the wall.
BULKHEAD -- A partition within a ship's hull or superstructure. It may be transverse or longitudinal, watertight, oiltight, gastight, or partially open. It may form part of the ship's subdivision for seaworthiness or otherwise.
BURNER WINDBOX -- A plenum chamber around a burner that maintains an air pressure sufficient for proper distribution and discharge of combustion air.
BUSBAR -- A heavy, rigid conductor used as a common connection for two or more electrical circuits.