Steam Calculators Glossary

Blowdown
Blowdown is saturated liquid continuously and/or routinely drained from a boiler to control the concentration of dissolved solids. These solids have no other way of leaving the boiler and can be harmful to the boiler at excessive concentrations.
Boiler Combustion Efficiency
The % of fuel energy that is directly added to the feedwater. Commonly 78% to 84%.
Condensate
Condensed steam that is collected and, if suitable, returned the boiler.
Contact Steam
Steam that comes in direct contact with the process materials. This cannot be collected and reused as it can potentially contain contaminants that can harm the system.
Critical-Point
The temperature and pressure at which the phase boundaries no longer exists.
[ 3,185.4 psig, 373.9 °C ]
Additional Info: http://en.wikipedia.org/wiki/Critical_point_(thermodynamics)
Deaerator
Removes dissolved gases from boiler feedwater by increasing the temperature to almost boiling.
Additional Info: http://en.wikipedia.org/wiki/Deaerator
Enthalpy
A measurement of the total energy of a thermodynamic system.
Specific Enthalpy [btu/lbm] A measurement of energy per unit mass.
Additional Info: http://en.wikipedia.org/wiki/Enthalpy
Entropy
A measure of the tendency of a process to be entropically favored, or to proceed in a particular direction.
Specific Entropy [kJ/kg/K] A measurement of entropy per unit mass.
Additional Info: http://en.wikipedia.org/wiki/Entropy
Feedwater
Water that is fed into the boiler after having been filtered, chemically treated, heated, and/or pressurized.
Flash
The process involving the reduction in pressure of a liquid causing a portion to vaporize (Flash). A flash tank allows for the separation of the resulting liquid and gas.
Additional Info: http://en.wikipedia.org/wiki/Flash_evaporation
Isenthalpic Process
A process that proceeds without any change in enthalpy.
Additional Info: http://en.wikipedia.org/wiki/Isenthalpic
Isentropic Efficiency
The energy actually removed as a percent (%) of the energy removed if the turbine were an isentropic process.
Additional Info: http://en.wikipedia.org/wiki/Steam_turbine#Isentropic_turbine_efficiency
Isentropic Process
A process that proceeds without any change in entropy.
Additional Info: http://en.wikipedia.org/wiki/Isentropic
Make up Water
Water added to the system to make-up for steam and water losses.
Quality
The ratio of Saturated Gas/Vapor to total mass.
Additional Info: http://en.wikipedia.org/wiki/Vapor_quality
Saturated Fluid (Liquid or Gas)
A substance that is at the vapor-liquid equilibrium which occurs at the pressure-dependent boiling point. The liquid and vapor components are individually referred to as Saturated Liquid and Saturated Gas/Vapor. If the substance is entirely one or the other, the individual component term can be used to describe the whole. Related: Quality
Additional Info: http://en.wikipedia.org/wiki/Vapor-liquid_equilibrium
Steam Turbine
A device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft.
Additional Info: http://en.wikipedia.org/wiki/Steam_turbine
Subcooled Liquid
Water with a temperature below the boiling point for its pressure.
Superheated Steam
Steam with a temperature above the boiling point for its pressure.
Triple-Point
The temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.
[ -14.6 psig, 0.0 °C ]
Additional Info: http://en.wikipedia.org/wiki/Triple_point