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B:

BAFFLE
A wall or plate that deflects gases or liquids

BAFFLE TILE
A tile that deflects gases.

BAFFLE-TYPE COLLECTOR
A baffle device used to deflect dust particles out of the gas stream.

BAG FILTER
This device recovers particles from dust-laden gas or air. This is achieved when the gas or air is pushed through the devices one or more bags.

BAG-TYPE COLLECTOR
A bag filter in which cylindrical bags are used as the cloth-filtering medium.

BAROMETRIC PRESSURE
Usually expressed in inches of mercury, barometric pressure is atmospheric pressure that has been determined using a barometer.

BASE LOAD
The portion of a station or boiler load that is constant for long periods of time.

BEADED TUBE END
When a tube of metal is formed, the rounded exposed end is referred to as the beaded tube end.

BLIND NIPPLE
A short piece of pipe or tube that is closed at one end.

BLOWDOWN
When boiler water is removed from the boiler, this water is called the “blowdown”. Blowdown is usually removed to maintain the desired concentration levels of suspended and dissolved solids, and also to remove any sludge.

BLOWDOWN SAFETY VALVE
This is the difference in pressure between when a safety valve is open and when it is closed.

BLOWDOWN VALVE
This valve regulates the concentration of solids in the boiler. It is not a drain valve.

BLOW-OFF VALVE
This valve is manually operated to reduce the concentration of solids in the boiler. It can also be used for draining purposes.

BLOWER
A fan that is used to force pressured air.

BOILER
Boilers are closed vessels that heat water, generate steam, superheat steam, or do a combination of all three. These processes occur under pressure or vacuum that is created by the application of heat from combustible fuels, electricity, or nuclear energy.

BOILER EFFICIENCY
This term technically applies to a measure of the fuel-to-steam efficiency. However, it is also often used to refer to the boiler’s combustion or thermal efficiency.

BOILER HORSEPOWER
The evaporation of 34-1/2 lbs of water per hour from a temperature of 212 °F into dry saturated steam at the same temperature. Equivalent to 33,475 Btu/hr.

BOILER RATING
This refers to the maximum heat output of the boiler and is measured in Kw.

BOILER SHELL
The outermost portion of the boiler’s cylinder.

BOILER WATER
Boiler water describes the circulating water in the boiler as it exists after the generated steam is separated and before the incoming feed water or chemicals are added.

BOILING
The change of state whereby a liquid becomes a vapor with the formation of bubbles.

BOILING OUT
A process to remove oils, greases, etc. by boiling highly alkaline water in boiler pressure parts.

BOOSTER FAN
Equipment that increases the flow or pressure of a gas.

BREECHING
A duct that connects a steam generating units to the stack. This duct transports the products of combustion.

BRIDGEWALL
The products of combustion pass over this wall that is located within a furnace.

BRITISH THERMAL UNIT (Btu)
A Btu is equal to approximately 252 calories. 1 Btu represents 1/180 of the heat required to raise 1 lb of water from 32 °F to 212 °F.

BUCKSTAY
A furnace or boiler wall is reinforced with this structural device to prevent motion of the wall.

BUNKER C OIL
High viscosity residual fuel oil that is commonly used in marine and stationary steam power plants.

BURNER
A device that introduces fuel and air into a furnace. This device controls the fuel or air’s velocity, turbulence, and concentration.

BURNER WINDBOX
This plenum chamber is located around the burner. Its role is to maintain the air at a pressure sufficient for proper distribution and discharge of secondary air.

BURNER WINDBOX PRESSURE
The pressure of air in the windbox or plenum chamber. This measures above atmospheric pressure.

BY-PASS
A route for fluid that permits a portion of the fluid to flow around the normal pass flow channel.

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C:

C
The symbol representation of the Carbon element, which is the main combustible constituent of all fuels.

CaCO3
They symbol representation of Calcium Carbonate.

CALORIE
A value that is about equal to the quantity of heat required to raise one gram of water 1 °C. A calorie can also be described as 1/100 of the heat required to raise the temperature of 1 gram of water from 0 °C to 100 °C at a constant atmospheric pressure. Another definition is: A calorie is 3600/860 joules.

CALORIMETER
A devise that determines the calorific value of a fuel.

CAPACITY FACTOR
A ratio of the average load that has been carried to the maximum design capacity.

CARBON
An organic element that is the principal combustible constituent of all fuels.

CARRYOVER
The solid and liquid chemicals that are entrained with the steam from a boiler.

CASING
A steam generating unit is either fully enclosed or partially enclosed by a casing. A casing is usually made of sheets of metal or other fire resistant material, such as fire resistant composition board.

CENTRAL STATION
Heat or steam are generated at this power or steam heating plant.

CENTRIFUGAL FAN
A device consisting of a fan rotor or wheel. The fan or wheel is contained within housing that discharges air a right angel to the wheel’s axis.+

CHEMICAL FEED PIPE
A pipe used to introduce treatment chemicals into the boiler water. It is generally fitted inside the boiler drum.

CHIMNEY
A stack made from metal, brick, or concrete.

CIRCULATION
Movement of steam and water within a unit that generates steam.

CIRCULATION RATIO
The ratio of water to steam in a circuit during a specific unit of time.

CIRCULATOR
This pipe or tube is usually located where the heat absorption is low. It is used to pass steam or water between the upper boiler drums and is also used to apply to the tubes that connect the headers of the horizontal water tube boilers with the drums.

CLEANOUT DOOR
A door that is used to access a boiler setting so that accumulated refuse can be removed.

CO
The chemical symbol for Carbon monoxide.

CO2
The chemical symbol for Carbon dioxide.

COLLECTOR
Gas borne solids are removed from flue gas using this device.

COLLOID
A colloid is a finely divided organic substance. This substance is used to inhibit dense scale from forming. Instead the sludge or suspended solids form which can be removed from the boiler.

COMBUSTIBLE LOSS
An amount of energy lost due to unliberated thermal energy. This occurs when it is not possible to completely oxidize 100% of the combustible matter in fuel.

COMBUSTIBLES
The constituents of fuel that will produce heat.

COMBUSTION
A chemical reaction in which oxygen combines with combustible elements of fuel. The product of this reaction is heat.

COMBUSTION AIR
Air, containing oxygen, which is used in combustion.

COMBUSTION CHAMBER
See Furnace.

COMBUSTION EFFICIENCY
A measurement of a burner’s effectiveness in terms of how well it burns the fuel. This value is significantly affected by the volume of excess air.

COMPLETE COMBUSTION
Full oxidation of a fuels combustible constituents.

CONCENTRATION
This term can refer to the weight of solids in a unit of boiler or feed water. It can also apply to the number of times dissolved solids have increased from the amount in the feedwater. This increase occurs as the result of water evaporation in the generation of steam.

CONDENSATE
Water that is condensed due to the production of steam.

CONDUCTION
A process whereby heat is transmitted through matter without any obvious motion of that matter.

CONDUCTIVITY
This term applies to a property of matter that relates heat flux to a temperature difference. It can also apply to the property of a water sample whereby electric currents are transmitted under a set of standard conditions.

CONTINUOUS BLOWDOWN
Removal of concentrated boiler water in an uninterrupted process. Occurs to control the total concentration of solids in the remaining water.

CONTROL
This term refers to a broad range of devices that are used in the manual or automatic regulation of a machine. If a control is automatic, its activity is usually triggered by a variation to normal conditions, such as a change in temperature, pressure, water level, or light.

CONTROL VALVE
The flow of materials such as air, gas, water, or steam are controlled using this device.

CONVECTION
The transmission of heat by the circulation of a liquid or gas. It may be natural, with the circulation caused by buoyancy affects due to temperature differences, or forced with circulation caused by a mechanical device such as a fan or pump.

CORROSION
A process in which metal is eroded due to chemical reactions occurring at its surface. In boilers, corrosion is usually the result of excess oxygen, CO2, or an acid.

CROWN SHEET
These are found in firebox boilers and are the plates forming the top of the furnace.

CRUDE OIL
A name that refers to unrefined petroleum.

CSD-1
An abbreviation used to refer to the ASME standard for Controls and Safety Devices.

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D:

DAMPER
Used to introduce a variable pressure drop in a system, this device helps regulate the flow of gases, such as air.

DAVIT
Found on large firetube boilers, this structure supports the front and rear boiler doors when they are open.

DEAERATION
The process whereby air and gases are removed from boiler feed water before it is introduced into a boiler.

DEGASIFICATION
The process whereby gases are removed from samples of steam. This is part of the purity test.

DELAYED COMBUSTION
Combustion that continues beyond the furnace. This process is also referred to as Secondary Combustion.

DESIGN LOAD
This is the maximum load that the steam generating unit has been designed for.

DESIGN PRESSURE
This is the pressure value that was used during the design of the boiler. This value contributes the minimum permissible thickness or physical characteristics of the boiler’s many parts.

DESIGN STEAM TEMPERATURE
This is the temperature value that the boiler has been designed to produce through steam.

DEW POINT
A determined temperature value at which condensation begins to occur.

DISENGAGING SURFACE
Steam is released from the surface of the boiler water, this surface is called the disengaging surface.

DISSOCIATION
A chemical reaction in which a chemical compound breaks down into its simpler parts. This often occurs when the temperature is increased beyond a certain point.

DISSOLVED SOLID
A name that refers to matter which was formerly solid but is now dissolved into the water’s solution.

DISTILLATE FUELS
The liquid fuel product that results from distilling crude petroleum.

DISTILLATION
The process whereby a substance is vaporized and then subsequently recovered through condensation. This usually results in a higher purity product.

DISTILLED WATER
Water that has undergone the distillation process (it has been vaporized and then condensed.

DOWNCOMER
The boiler or waterwall’s tube through which the circulating system’s fluid flows downward.

DOWNTIME
Refers to the amount of time in which a piece of equipment is not operational.

DRAFT
In a furnace stack or gas passage of a steam generating unit this term refers to a difference between atmospheric pressure and some lower pressure.

DRAFT DIFFERENTIAL
A term referring to a difference in static pressure between two areas.

DRAFT GAUGE
A tool used to measure draft, usually in inches of water.

DRAIN
Used to remove all water from the pressure parts, this valved connection is found at the lowest point.

DRUM
A cylindrical shell closed at both ends designed to withstand internal pressure.

DRY AIR
A name for air that does not contain water vapor, or that contains less water vapor than another compared substance.

DRYBACK BOILER
Firetube boiler with a refractory lined back door. Door opens to allow maintenance and/or inspection.

DRY GAS
A name for gas that does not contain water vapor.

DRY-GAS LOSS
The loss representing the difference between the heat content of the dry exhaust gases and their heat content at the temperature of ambient air.

DRY STEAM
Steam that does not contain moisture. If it is commercial dry steam then it does not contain more than 0.5% moisture.

DUCT
A passage which allows air or gas flow to flow through.

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E:

ECONOMIZER
A device that conserves wasted heat by transferring heat from flue gases to incoming feedwater.

EDR
Equivalent direct radiation is the rate of heat transfer from a radiator or convector. It is equivalent to the square feet of surface area necessary to transfer heat at the same rate at which it is produced by a generator. A single boiler horsepower equals 140 ft2 EDR.

EFFICIENCY
The ratio of output to input. See also Combustion, Fuel-to-Steam and Thermal Efficiency.

EJECTOR
A device that uses a jet of water or other fluid in order to remove a fluid from hoppers or tanks.

ELECTRIC BOILER
A boiler design that uses electric energy as the source of heat.

ELECTROSTATIC PRECIPITATOR
A device for collecting dust, mist or fume from a gas stream, by placing an electrical charge on the particle and removing that particle onto a collecting electrode.

ENTRAINMENT
The process whereby steam conveys particles of water or solids fro the boiler water.

EQUALIZER
The name for connections that exist between parts of a boiler and serve to equalize pressures.

EQUIVALENT EVAPORATION
Evaporation expressed in pounds of water evaporated from a temperature of 212 °F to dry saturated steam at 212 °F.

EVAPORATION
The physical change of state that occurs when a

EVAPORATION RATE
The quanity of water that evaporates in a given amount of time, usually expressed in pounds of water.

EXCESS AIR
Air supplied for combustion in excess of that theoretically required for complete oxidation.

EXPANSION JOINT
A joint that permits expansion movement and prevents the creation of stress.

EXPLOSION DOOR
A furnace or boiler setting door that will open once a pre-determined gas pressure is reached.

EXTERNAL TREATMENT
A process to treat boiler feed water before it is introduced into the boiler.

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F:

FAN
A device that consists of a rotor and a housing unit. Fans move air or gases at low pressure differentials.

FAN PERFORMANCE
A measure of fan operation in terms of volume, total pressures, static pressures, speed, power input, mechanical and static efficiency, at a stated air density.

FAN PERFORMANCE CURVES
The graphical presentation of total pressure, static pressure, power input, mechanical and static efficiency as ordinates and the range of volumes as abscissa, all at constant speed and air density.

FEED PUMP
A device that pumps water into a boiler

FEEDWATER
Water introduced into a boiler during operation. It includes make-up and return condensate.

FEEDWATER TREATMENT
The treatment of boiler feed water by the addition of chemicals to prevent the formation of scale or to eliminate other objectionable characteristics.

FGR
An acronym for Flue Gas Recirculation. This is the recirculation of flue gas with combustion air. The purpose of FGR is to reduce NOx emissions.

FILTER
A porous material that allows fluid to pass through but traps matter that was being held in suspension.

FIN
An extended surface that experiences energy transfer through conduction within its boundaries. Fins also transfer energy with their surroundings by convection and/or radiation. They are used principally to enhance heat transfer because they increase surface area.

FIN TUBE
A tube that has fins.

FIRED PRESSURE VESSEL
A vessel that contains a pressurized fluid which is exposed to heat. The heat comes from the combustion of fuel.

FIRETUBE
A type of boiler design in which combustion gases flow inside the tubes and water flows outside the tubes.

FIRING RATE CONTROL
A pressure temperature or flow controller which controls the firing rate of a burner according to the deviation from pressure or temperature set point. The system may be arranged to operate the burner on-off, high-low or in proportion to load demand.

FIXED CARBON
The carbonaceous residue less the ash remaining in the test container after the volatile matter has been driven off in making the proximate analysis of a solid fuel.

FLAME
The name for a body of burning gas or vapor.

FLAME DETECTOR
A device which indicates if a fuel (liquid, gaseous, or pulverized) is burning, or if ignition has been lost. The indication may be transmitted to a signal or to a control system.

FLAME PROPAGATION RATE
The speed at which an ignition can travel through a combustible mixture.

FLAME SAFEGUARD
A control that sequences the burner through several stages of operation to provide proper air purge, ignition, normal operation, and shutdown for safe operation.

FLAMMABILITY
The state of being susceptible to combustion.

FLASHING
A process whereby steam is produced when water is discharged inot a region where the pressure is lower than the saturation pressure that corresponds to the water’s temperature

FLASH POINT
The lowest temperature at which, under specified conditions, fuel oil gives off enough vapor to flash into a momentary flame when ignited.

FLUE
A passage for products of combustion.

FLUE GAS
The gas that is produced when combustion occurs in the flue.

FOAMING
The continuous formation of bubbles which have sufficiently high surface tension to remain as bubbles beyond the disengaging surface.

FORCED CIRCULATION
The process of circulating a boiler’s water by means that are external to the device.

FORCED-DRAFT FAN
A device that supplies air under pressure to the fuel burning equipment.

FOULING
The accumulation of refuse in gas passages or on heat absorbing surfaces which results in undesirable restriction to the flow of gas or heat.

FM
An acronym for Factory Mutual.

FREE ASH
Ash that is not included in the fixed ash.

FUEL
A substance containing combustible material. It is used for generating heat.

FUEL-AIR MIXTURE
A name that applies to a combination of air and fuel.

FUEL-AIR RATIO
A value that represents the ration of fuel to air, based on their weight or volume.

FUEL OIL
Liquid fuel that is derived from coal or petroleum.

FUEL-TO-STEAM EFFICIENCY
The ratio of heat added to boiler feedwater to produce the output steam to the amount of energy inputted with fuel.

FURNACE
A cavity or enclosed space in which combustion of fuel occurs.

FURNACE PRESSURE
Pressure occurring inside the combustion chamber; positive if greater than atmospheric, negative if less than atmospheric, and neutral if equal to atmospheric.

FURNACE VOLUME
The cubic contents of the furnace or combustion chamber.

FUSIBLE PLUG
A plug that is hollowed and contains a material with a low melting point.

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G:

GAS ANALYSIS
A process that determines the components in a gaseous mixture.

GAS BURNER
A burner that uses gas or fuel.

GAS PRESSURE REGULATOR
A spring loaded, dead weighted or pressure balanced device which will maintain the gas pressure to the burner supply line.

GAUGE COCK
A valve that is attached to a water column or drum. This valve is used to check the column or drum’s water level.

GAUGE GLASS
The transparent part of a water gauge assembly connected directly or through a water column to the boiler, below and above the water line, to indicate the water level in a boiler.

GAUGE PRESSURE
The pressure above atmospheric pressure.

GRADE
A classification given to oil, which represents its quality. Oil’s grade is usually based on ASTM specifications.

GRAINS PER CU-FT
The term for expressing dust loading in weight per unit of gas volume (7000 grains equals one pound).

GRAINS (WATER)
The name for a unit of measure that is used in water analysis. This unit measures impurities in water and 17.1 grains = 1 part per million – ppm.

GRAVITY
Weight index of fuels: liquid, petroleum products expressed either as specific, Baume or A.P.I. (American Petroleum Institute) gravity; weight index of gaseous fuels as specific gravity related to air under specified conditions; or weight index of solid fuels as specific gravity related to water under specified conditions.

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H:

HANDHOLE
A opening that provides access to a pressure part. These openings usually do not exceed 6 inches at their widest point.

HANDHOLE COVER
A handhole closure.

HARDNESS
The measure of how much calcium and magnesium salts are in a given amount of water. Hardness is usually expressed as grains per gallon or ppm as CaCO3.

HARD WATER
Water which contains calcium or magnesium in an amount which require an excessive amount of soap to form a lather.

HEAT AVAILABLE
The amount of thermal energy that is capable of being absorbed for useful work.

HEAT BALANCE
An accounting of the distribution of the heat input, output and losses.

HEAT EXCHANGER
A device, usually a vessel, in which heat can be transferred from one substance or medium to another.

HEAT RELEASE RATE
Rate that describes the heat available per square foot of heat-absorbing surface in the furnace or per cubic foot of volume.

HEATING SURFACE
Surfaces that come in contact with the products of combustion on one side and water on another side. These surfaces are measured based on the side that receives the heat.

HEATING VALUE
The quantity of heat released by a fuel through complete combustion. It is commonly expressed in Btu per lb, per gallon, or cu-ft.

HIGH GAS PRESSURE CONTROL
A control that will stop the burner once the gas pressure reaches a specific point.

HIGH OIL TEMPERATURE CONTROL
A control that allows for the stop or control of a burner should the oil temperature climb too high.

HYDROCARBON
A chemical compound of hydrogen and carbon.

HYDROSTATIC TEST
A test used to measure the strength and tightness of a closed pressure vessel using water pressure.