Boiler glossary L
|LABOUR -- A vessel is said to labour when she rolls or
LABYRINTH PACKING -- A type of gland, with radial or axial clearance, used e.g., in steam engines and turbines.
LAGGING -- A light gauge steel covering used over a boiler, usually combined with insulation, to provide a low temperature outer surface.
LAMINAR FLOW -- Very smooth flow in which all the molecules are traveling in generally the same direction. For internal flows, it occurs at Reynolds numbers less than 2000.
LAMONT BOILER -- A once-through or semi-flash boiler in which the feedwater is supplied to the upper ends of long closely spaced tubes of mall diameter, from which the water and the steam pass to a separating drum.
The boiler is named after the engineer Navy Lieutenant Commander Walter Douglas Lamont.
LANCASHIRE BOILER -- A cylindrical steam boiler having two longitudinal furnace tubes containing internal grates at the front. After leaving the tubes the gases pass to the front along a bottom flue, and return to the chimney along side or wing flues.
Sir William Fairbairn developed the Lancashire boiler in 1844
LATENT HEAT -- The heat which is required to change the state of a substance from solid to liquid, or from liquid to gas, without change of temperature. The numerical value of the specific latent heat is the amount of heat required to change the state of unit mass. Most substances have a latent heat of fusion (melting) and a latent heat of evaporation. In thermodynamics, heat supplied at constant pressure is called enthalpy, and thus specific latent heat of evaporation is called enthalpy of evaporation.
LIFT-OFF -- This condition occurs when the fuel or fuel/air mixture velocity is too high, thus allowing the fuel to exit the stabilizing zone before it has achieved its ignition temperature.
LINING -- The material used on the side of a furnace wall. It is usually of high grade refractory tile or brick or plastic refractory material.
LINK-MOTION -- A valve gear, invented by Stephenson, for reversing and controlling the cut-off of a steam-engine. It consists of a pair of eccentrics, set for ahead and reverse rotation, connected to the ends of a slotted link carrying a block attached to the valve rod. Variation of the link position makes either eccentric effective, and also varies the cut-off.
LIVE STEAM -- Steam available directly from a boiler under full pressure.
LOW DRAFT SWITCH -- A control to prevent the burner operation if the draft is too low. Used primarily with mechanical draft.
LOW FIRE START -- The firing of a burner with controls in a low-fire position to provide safe operating condition during light off.
LOW LOW WATER LEVEL TRIP -- A device that shuts down the fuel supply when the water level in the boiler drops below its operating level. This prevents burning out of tubes, boiler damage or possible boiler explosion.
LOW Nox BURNER -- A burner designed to reduce Nitrogen oxides emissions.
LOW PRESSURE AIR ATOMIZER -- The fuel is forced to rotate in a fixed cup by means of a forcefully rotating primary airflow.
LOWER HEATING VALUE -- LHV, The theoretical heat the combustion process can release if the fuel and oxidant are converted to 100% efficiency to CO2 and H2O vapor.
LUG -- Any projection, like an ear, used for supporting or grasping.