Boiler glossary

Boiler glossary E

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ECCENTRIC SHEAVE -- The sheave of an eccentric, often formed intergral with the shaft. (Reciprocating steam engine)
ECCENTRIC STRAP -- A narrow split bearing, fitting on to an eccentric sheave and bolted to the end of a valve rod, ect.; corresponds to the "big end" of the connecting-rod.
ECONOMIZER -- A heat exchanger that transfers heat from the gases of the combustion to the Boiler Feedwater.
EDUCTER -- A device to draw air out.
EJECTOR -- A device for exhausting a fluid by entraining it by a high-velocity steam or air jet.
ELECTRIC BOILER -- A boiler in which electric energy is used as the source of heat.
Low voltage boilers are mainly heated by means of electric elements.
High voltage boilers are always heated by means of electrodes directly in the water.
Element boilers often range from 20 to 3000 kW for a standard voltage of 400 Volt (3-phase). Electrode boilers range from 100kW to 1500kW for 400Volt and 1 to 60MW for a standard voltage of 10kV (3-phase).
EMERGENCY 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.
ENDOTHERMIC -- A process that absorbs heat.
ENTHALPY -- Thermodynamic property of a working substance defined as H = U+PV, where U = internal energy, P = pressure and V = volume of system. Useful in studying flow process, replacing total heat.
ENTRAINMENT -- Transport of small liquid particles in vapor, e.g., when drops of water are carried over in steam.
EVAPORATIVE CAPACITY -- The mass of steam at a stated temperature and pressure produced in on hour from a unit area of heating surface from feedwater at a stated temerarure, when steaming at the most economical rate. Measured in kg/m² h (or lb/ft² h).
Also called evaporation rate.
EXCESS AIR -- Air supplied for combustion in excess of the air theoretically required for complete combustion of the fuel.
EXHAUST GAS BOILERS -- A water tube boiler.
EXHAUST GAS DAMPER -- Used to control the pressure in an exhaust gas boiler. It bypasses the heat exhaust gases to reduce the steam production in the exhaust gas boiler.
Nowadays a control valve normally dumps the excess steam to a dump condenser.
EXOTHERMAL -- A process that gives out heat.
EXPANSION JOINT-- A junction that allows for expansion and contraction.
EXPRESS BOILER -- In these boilers the tubes are made of smaller diameter than those used in other boilers. The Yarrow express boilers are of similar construction as the large tube Yarrow boilers with the exception that the tubes are smaller in diameter and much more closely arranged.
EXTERNAL MIX STEAM ATOMIZER -- Is designed to make full use of pressure jet atomization at high outputs and full use of blast atomization at low outputs.