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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.
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I:
IGNITION
The start of combustion.
IGNITION TEMPERATURE
Lowest temperature of a fuel at which combustion becomes self-sustaining.
ILLUMINANTS
Compounds of light oil or coal that will readily burn with a luminous (bright) flame. Common Illuminants include ethylene, propylene, and benzene.
INCOMPLETE COMBUSTION
A process in which only part of the fuel’s combustible constituents are oxidized.
INDUCED DRAFT FAN
A fan exhausting hot gases from the heat absorbing equipment.
INERT GASEOUS CONSTITUENTS
Gases that will not undergo combustion but which may still be present in a fuel. These include gases such as nitrogen.
INHIBITOR
A device that selectively limits a chemical’s ability to interact. For example, in boilers acid is used to remove scale, but an inhibitor prevents that acid from attacking the boiler’s metal.
INJECTOR
A tool that entrains and delivers feed water into a boiler using a stream jet.
INSULATION
Material with low thermal conductivity that reduces heat loss.
INTEGRAL BLOWER
A blower built as an integral part of a device to supply air thereto.
INTEGRAL-BLOWER BURNER
A burner design that uses a blower as an integral component.
INTERLOCK
A device to prove the physical state of a required condition, and to furnish that proof to the primary safety control circuit.
INTERMITTENT BLOWDOWN
A process whereby boiler water is blown down at intervals.
INTERNAL TREATMENT
The treatment of boiler water by introducing chemicals directly into the boiler. ION - A particle that carries a positive or negative charge. IRI – The acronym for Industrial Risk Insurers.
ION
A particle that carries a positive or negative charge.
IRI
The acronym for Industrial Risk Insurers.
LAGGING
The name for a light gauge steel covering that is used in combination with insulation over a boiler. This combination provides a low temperature outer surface.
LEAKAGE
The uncontrolled quantity of fluid which enters or leaves through the enclosure of air or gas passages.
LIBERATION
Please see Heat Release.
LIMIT CONTROL
A device that is used to complete or break an electrical circuit once specific pressures or temperatures are reached. Also see: Interlock
LINING
The material used on the furnace side of a furnace wall. It is usually of high grade refractory tile or brick or plastic refractory material.
LOAD
A word used to describe the rate of output required and also to describe the weight carried.
LOAD FACTOR
A ratio value that compares the average load at a given time to the maximum load carried during that same period.
LOW GAS PRESSURE CONTROL
A device that inhibits the burner should the gas pressure drop too low.
LOW OIL TEMPERATURE CONTROL
Also known as a Cold Oil Switch, this control prevents the burner from operating once the temperature of the oil drops below a specific point.
LOW WATER CUTOFF
Safety device that shuts off the boiler/burner in the event of low water, preventing pressure vessel failure.
LUG
A projecting item that is used for grasping or supporting.
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M:
MAKE-UP
A name for water that is added to a boiler feed in order to compensate for water lost due to exhaust, blowdown, leakage, etc.
MANHOLE
The opening in a pressure vessel of sufficient size to permit a man to enter.
MANIFOLD
A device (usually a pipe or header) used in the exchange of fluid from a number pipes and tubes.
MANUAL GAS SHUTOFF VALVE
A manually operated valve in a gas line for the purpose of completely turning on or shutting off the gas supply.
MANUFACTURED GAS
Unlike natural gas, this gas is manufactured from coal, oil, or other substances.
MAXIMUM ALLOWABLE WORKING PRESSURE
A value that represents the highest maximum gauge pressure permissible inside a completed boiler. Commonly referred to as the MAWP, this value is less than or equal to the lowest design pressure determined for any of its parts. The pressure setting of the pressure release devices are based on this value.
MAXIMUM CONTINUOUS LOAD
The maximum load which can be maintained for a specified period.
MAXIMUM INSTANTANEOUS DEMAND
A load demand that is placed suddenly on a boiler. Extending beyond this load demand is likey to lead to an unbalanced condition in the boiler’s surface release conditions and/or internal flow pattern.
MECHANICAL ATOMIZING OIL BURNER
A device that uses the pressure of oil to create atomization.
MECHANICAL DRAFT
The negative pressure created by mechanical means.
MICRON
The measurement usually used to describe the diameter of dust. It is a fraction that represents one millionth of a meter, or 0.000039 in. or 1/25400 in.
MINIATURE BOILER
Fire pressure vessels which do not exceed the following limits: 16 in. inside diameter of shell; 42 in., overall length to outside of heads at center; 20 sq ft water heating surface; or 100 psi maximum allowable working pressure.
MMBtu
The representation for Millions of Btus (British Thermal Units).
MOISTURE
Water that is in its liquid or vapor phase.
MOISTURE IN STEAM
the percentage by weight of water particles that are carried in steam.
MOISTURE LOSS
The boiler flue gas loss representing the difference in the heat content of the moisture in the exit gases and that at the temperature of the ambient air.
MULTIFUEL BURNER
A burner that is designed to burn more than one fuel.
MULTIPORT BURNER
The name for boilers that have several nozzles for the discharge of fuel and air.
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NATURAL CIRCULATION
The process whereby water circulates throughout a boiler due to differences in density.
NATURAL GAS
The name for gaseous fuel that occurs in nature.
NET POSITIVE SUCTION HEAT (NPSH)
The liquid pressure that exists at the suction end of a pump. If the NPSH is insufficient, the pump can cavitate.
NOx
An abbreviation that stands for all chemical compounds in the family of nitrogen oxides.
NOZZLE
A device that is connected to a drum or shell and allows for the outlet or inlet of fluids.
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O:
OIL BURNER
A device used to fire oil.
OIL HEATING AND PUMPING SET
A group of apparatus consisting of a heater for raising the temperature of the oil to produce the desired viscosity, and a pump for delivering the oil at the desired pressure.
OPERATING CONTROL
A switch or control that is used to start and stop a burner.
OPERATING PRESSURE
A boiler’s pressure when it is in operation.
ORGANIC MATTER
Compounds that contain carbon. These are generally associated with living organisms.
ORIFICE
(1) The opening from the whirling chamber of a mechanical atomizer or the mixing chamber of a steam atomizer through which the liquid fuel is discharged.
(2) A calibrated opening in a plate, inserted in a gas stream for measure velocity of flow.
ORSAT
A device used in gas—analysis. This apparatus measures certain gaseous constituents by absorption in separate chemical solution.
OVERPRESSURE
Minimum operating pressure of a hot water boiler sufficient to prevent the water from steaming.
OXIDATION
The chemical process whereby a substance reacts in chemical combination with oxygen.
OXIDIZING ATMOSPHERE
An atmosphere which tends to promote the oxidation of immersed materials.
OXYGEN ATTACK
A circumstance in which oxygen creates corrosion or pitting in a boiler.
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PACKAGED BOILER
A boiler that is presented with all of its components including its burner, controls and auxiliary equipment. This boiler designed as a single engineered package and is ready for on-site installation.
PACKAGED STEAM GENERATOR
See Packaged Boiler.
PARTICLE SIZE
The measured size of a dust particle. Usually expressed in microns or the percent that will pass through a standard mesh screen.
PASS
A vessel that operates as a confined passageway. A pass contains heating surfaces and allows water to flow in only one direction.
PERFECT COMBUSTION
The complete oxidation of all the combustible constituents of a fuel, utilizing all the oxygen supplied.
PETROLEUM
A naturally occurring mineral oil that predominately consists of hydrocarbons.
pH
The hydrogen ion concentration of a water to denote Acidity or Alkalinity. A pH of 7 is neutral. A pH above 7 denotes alkalinity while one below 7 denotes acidity. This pH number is the negative exponent of 10 representing hydrogen ion concentration in grams per liter. For instance a pH of 7 represent 10-7 grams per liter.
PILOT
A flame that ignites the fuel at the main burner(s). Also known as an Ignitor.
PITOT TUBE
An instrument which will register total pressure and static pressure in a gas stream, used to determine its velocity.
PITTING
The damage created by an oxygen attack or another corrosive chemical. Pitting creates localized depressions in the boiler’s metal surfaces.
PORT
An opening through which fluid passes.
POST PURGE
A method of scavenging the furnace and boiler passes to remove all combustible gases after flame failure controls have sensed pilot and main burner shutdown and safety shut-off valves are closed.
ppm
An abbreviation for parts per million. This measurement is used in chemical determinations as one part per million parts by weight.
PRECIPITATE
To separate materials from a solution by the formation of insoluble matter by chemical reaction. The material which is removed.
PRECIPITATION
The process of removing solid or liquid particles from a fluid.
PREHEATED AIR
The name for air that measures at a temperature exceeding that of the ambient air.
PRESSURE
A measurement that represents the force per unit of area.
PRESSURE DROP
A situation that occurs when resistance to flow causes a difference in pressure between two points in a system.
PRESSURE VESSEL
A closed vessel or container designed to confine a fluid at a pressure above atmospheric.
PRIMARY AIR
A name for air that has been introduced to the burner at the same time as fuel.
PRIMING
The discharge of steam containing excessive quantities of water in suspension from a boiler, due to violent ebullition.
PROCESS STEAM
A name for steam that is used for industrial purposes, as opposed to for producing power.
PRODUCTS OF COMBUSTION
The vapors, solids, and gases that result from fuel’s combustion.
PULSATION
Rapid fluctuations in pressure.
PURGE
The process whereby air is introduced into a furnace and the boiler flue passages. This air is introduced in such a way that it completely replaces the air or gas-air mixture currently in the vessel.
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R:
RADIATION LOSS
A value that accounts for the heat lost from a boiler to the ambient air through conduction, radiation, and convection.
RATED CAPACITY
The manufacturers stated capacity rating for mechanical equipment; for instance, the maximum continuous capacity in pounds of steam per hour for which a boiler is designed.
RATE OF BLOWDOWN
A rate normally expressed as a percentage of the water fed.
RATING
Please ee "Load."
RAW WATER
Untreated water that is supplied to the plant.
REACTION
A process whereby chemicals change or transform when two substances interact.
REASSOCIATION
The process whereby dissociation products are recombined.
RECIRCULATION
The process whereby part of a flowing fluid is reintroduced into a cycle.
REDUCING ATMOSPHERE
An atmosphere which tends to
1) promote the removal of oxygen from a chemical compound;
2) promote the reduction of immersed materials.
REDUCTION
The process whereby oxygen is removed from a chemical compound.
REFRACTORY
Brickwork or castable used in boilers to protect metal surfaces and for boiler baffles.
RELATIVE HUMIDITY
A ratio comparing the current mass of water vapor in a unit volume to gas to the maximum volume. Temperature and pressure must remain constant.
RELIEF VALVE (Safety Relief Valve)
An automatic pressure relieving device actuated by the pressure upstream of the valve and characterized by opening pop action with further increase in lift with an increase in pressure over popping pressure.
RESIDUAL FUELS
Products remaining from crude petroleum by removal of some of the water and an appreciable percentage of the more volatile hydrocarbons.
RESIN
A bead-like material used in chemical exchange for softeners and dealkalizers.
RESISTANCE
The process whereby gas flow is impeded. For example, a pressure drop or draft loss through a dust collector is considered as resistance. This process is usually measured in inches water column (iwc).
RETURN FLOW OIL BURNER
A burner design in which pat of the oil that is supplied to the atomizer is removed and returned to storage during the mechanical atomizing process.
RINGELMANN CHART
A series of four rectangular grids of black lines of varying widths printed on a white background, and used as a criterion of blackness for determining smoke density in stack gas streams.
ROTARY OIL BURNER
A device used to atomize through feeding oil into a rapidly rotating cup.
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SADDLE
A device used for the purpose of support. Usually a casting, fabricated chair, or other member.
SAFE WORKING PRESSURE
Please see "Design Pressure."
SAFETY VALVE
A spring loaded valve that automatically opens when pressure attains the valve setting. Used to prevent excessive pressure from building up in a boiler.
SAFETY SHUT-OFF VALVE
A valve that can be manually opened and electrically latched. When de-energized, this valve allows for automatic shut off of the fuel.
SAMPLING
The removal of a portion of a material for examination o analysis.
SATURATED AIR
The name for air that contains the maximum amount of water vapor that it can hold at its current pressure and temperature values.
SATURATED STEAM
Steam at the temperature and pressure at which evaporation occurs.
SATURATED TEMPERATURE
The temperature value that represents the evaporation point. Saturated temperature must be associated with a particular pressure value.
SATURATED WATER
Water at its boiling point.
SCALE
The hard coating that can form on the surface of boiler pressure parts.
SECONDARY AIR
Air that is supplied in supplement to the primary air. This air is used for combustion.
SECONDARY TREATMENT
A process whereby boiler feed water is treated. Also refers to the treating of internal boiler water, following its primary treatment.
SEDIMENT
(1) Matter in water which can be removed from suspension by gravity or mechanical means.
(2) A non-combustible solid matter which settles out at bottom of a liquid; a small percentage is present in residual fuel oils.
SEGREGATION
The tendency of refuse of varying compositions to deposit selectively in difference parts of the unit.
SELF-SUPPORTING STEEL STACK
A steel stack that has been designed with enough strength that it can support its own weight without the help of lateral supports.
SERVICE WATER
General purpose water which may or may not have been treated for a special purpose.
SHELL
A pressure vessel’s cylindrical portion.
SLUDGE
Sedimentary deposits that are removed by blowing down. Sludge is water-formed and soft.
SLUG
A large "dose" of chemical treatment applied internally to a steam boiler intermittently. Also used sometimes instead of "priming" to denote a discharge of water out through a boiler steam outlet in relatively large intermittent amounts.
SMOKE
Small gas borne particles of carbon or soot, less than 1 micron in size, resulting from incomplete combustion of carbonaceous materials and of sufficient number to be observable.
SOFTENING
The process through which scale formation is reduced by limiting water’s calcium and magnesium impurities
SOFT WATER
Water which contains little or no calcium or magnesium salts, or water from which scale forming impurities have been removed or reduced.
SOLUTION
A liquid that contains dissolved substances. Example, boiler water.
SOOT
Particles of carbon that are derived from hydrocarbons and remain unburned.
SOOT BLOWER
A mechanical device for discharging steam or air to clean heat absorbing surfaces.
SPALLING
The action whereby internal stress causes refractory material to break off.
SPECIFIC HEAT
The quantity of heat, expressed in Btu, required to raise the temperature of 1 lb of a substance 1°F.
SPECIFIC HUMIDITY
The weight value assigned to water vapor that is in a gas water-vapor mixture. This value is represented per unit weight of the dry gas.
SPRAY ANGLE
The geometric angle formed by liquid fuel when it is discharge from a mechanical rotary atomizer. A spray angle is also sometimes formed by steam or air atomizers.
SPRAY NOZZLE
A nozzle from which a liquid fuel is discharged in the form of a spray.
STACK
A vertical conduit, which due to the difference in density between internal and external gases, creates a draft at its base.
STACK DRAFT
A measure of the draft that occurs at a stack’s inlet.
STACK EFFECT
That portion of a pressure differential resulting from difference in elevation of the points of measurement.
STACK EFFLUENT
The gas and solid products that are discharged from stacks.
STAGNATION
A state of being in which matter is free from movement or lacks circulation.
STANDARD AIR
Dry air weighing 0.075 lb per cu ft at sea level (29.92 in. Barometric Pressure) and 70 °F.
STANDARD FLUE GAS
The name for gas that weighs 0.078 lb per cu ft at sea level (29.92 in.Barometric Pressure) and 70 °F.
STATIC PRESSURE
A value assigned to a fluid’s potential energy.
STEAM
Water that is in its vapor phase and is not mixed with other gases.
STEAM ATOMIZING OIL BURNER
A burner for firing oil which is atomized by steam. It may be of the inside or outside mixing type.
STEAM BINDING
A restriction in circulation due to a steam pocket or a rapid steam formation.
STEAM GAUGE
A measurement tool that indicates the pressure of steam.
STEAM GENERATING UNIT
A unit to which water, fuel, and air are supplied and in which steam is generated. It consists of a boiler furnace, and fuel burning equipment, and may include as component parts water walls, superheater, reheater, economizer, air heater, or any combination thereof.
STEAM PURITY
The degree of contamination that is present in steam, as expressed in ppm.
STEAM QUALITY
A value, given as a percentage, that represents the weight of vapor in a steam and water mixture.
STEAM SEPARATOR
A tool used to remove entrained water from steam.
STRAINER
A tool, such as a filter, that retains solid particles while allowing liquids to pass.
STRATIFICATION
Non-homogeneity existing transversely in a gas stream.
STUD
A pin that serves to support or attach.
SUPERHEATED STEAM
Steam with its temperature raised above that of saturation. The temperature in excess of its saturation temperature is referred to as superheat.
SURFACE BLOWOFF
Removal of water, foam, etc. from the surface at the water level in a boiler. The equipment for such removal.
SURGE
A process of sudden displacement or movement of water in a drum or closed vessel.
SUSPENDED SOLIDS
The name given to boiler water’s undissolved solids.
SWINGING LOAD
A load whose value changes over relatively short intervals.
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TERTIARY AIR
Air that is supplied to a furnace during combustion as a supplement to the primary and secondary air.
THEORETICAL AIR
The amount of air that would be required for perfect, 100% combustion.
THEORETICAL DRAFT
The draft which would be available at the base of a stack if there were no friction or acceleration losses in the stack.
THEORETICAL FLAME TEMPERATURE
Please see "Adiabatic Flame Temperature."
THERM
this unit of heat is usually applied to gas. One therm = 100,000 Btu.
THERMAL EFFICIENCY
A representation of a boiler’s efficiency. The thermal efficiency is based on the ratio of heat absorbed to total heat input. Thermal efficiency does not take heat loss from boiler shell into account.
THERMAL SHOCK
A cycle of temperature swings that result in failure of metal due to expansion and contraction.
THERMOCOUPLE
An instrument used to measure temperature.
TILE
A refractory that is preformed and usually applied to shapes other than standard brick.
TOTAL AIR
The sum of all air supplied to the fuel and combustion products. Also represented as Percent Total Air, which is the ratio of total air to theoretical air.
TOTAL PRESSURE
The total value of velocity and static pressures.
TOTAL SOLIDS CONCENTRATION
The weight of dissolved and suspended impurities in a unit weight of boiler water, usually expressed in ppm.
TRAP
A receptacle in which all undesirable material is collected.
TREATED WATER
Water which has been chemically treated to make it suitable for boiler feed.
TRIM
Ancillary boiler components, like water level controls, pressure controls, and temperature controls.
TUBE
A hollow cylinder that allows for the conveyance of fluid.
TUBE HOLE
A hole in a heater, drum, or tube sheet that is used to accommodate a tube.
TURBULENT BURNER
A burner in which fuel and air are mixed and discharged into the furnace in such a manner as to produce turbulent flow from the burner.
TURNDOWN RATIO
The ratio of maximum fuel or steam input to minimum fuel or steam input. Also used to describe the ratio of maximum boiler output to minimum boiler output.
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ULTIMATE ANALYSIS
Please see "Analysis Ultimate."
UL LISTED
Product certification that indicates the product meets safety standards determined by Underwriters Laboratories. (ULC and cUL indicate Canadian requirements.)
UNACCOUNTED-FOR LOSS
This is an amount of heat that has been unaccounted for in calculations that sum the heat absorbed by the unit and all known losses. It is the difference between 100% and the sum of the other known heat percentages.
UNBURNED COMBUSTIBLE
The combustible portion of the fuel which is not completely oxidized.
UNFIRED PRESSURE VESSEL
A type of vessel design that is constructed to withstand internal pressure.
USE FACTOR
The ratio of hours that a device is in operation compared with the total amount of hours in a given period.
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VA
An acronym for Volt amperes.
VAPOR
Evaporation’s gaseous product.
VAPORIZATION
The process whereby liquid changes to the vapor phase.
VELOCITY PRESSURE
A measurement that represents a fluid’s kinetic energy.
VENT
An opening in a vessel or other enclosed space for the removal of gas or vapor.
VERTICAL FIRING
A burner design in which the air and fuel are discharged into the furnace in a vertical, rather than horizontal, direction.
VISCOSITY
Measure of the internal friction of a fluid or its resistance to flow.
VOLATILE MATTER
The products that are emitted by a material such as gas or vapor.
VOLUME OF AIR
The number of cu ft of air per min expressed at fan outlet conditions.
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WASTE HEAT
The heat discharged from non-combustible gases into the environment.
WATER
A clear liquid that is chemically formed by 2 parts of hydrogen and sixteen parts oxygen by weight.
WATER COLUMN
A vertical tubular member connected at its top and bottom to the steam and water space respectively of a boiler, to which the water gauge, water level controls, and fuel cutoff may be connected.
WATER GAUGE
The name for a gauge glass and those fittings used for attachment.
WATER HAMMER
A sudden increase in water pressure that occurs as the result of an instantaneous conversion of momentum to pressure.
WATER LEVEL
The height of water in a boiler.
WATER SOFTENER
A product used to remove hardness from water. This process occurs due to an ion exchange of sodium with calcium and magnesium.
WATER TUBE
A tube in a boiler having the water and steam on the inside and heat applied to the outside.
WATER VAPOR
Also known as steam, the term water vapor is specifically used for steam that has a low absolute pressure.
WEEP
A term usually applied to a minute leak in a boiler joint which forms droplets (or tears) of water very slowly.
WETBACK BOILER
Firetube boiler design wherein the back portion of the boiler has a water jacket.
WET-BULB TEMPERATURE
This is the temperature value of adiabatic saturation and is often used to measure humidity. It represents the lowest temperature value that a water wetted body can attain when it is exposed to an air current.
WETNESS
A descriptive term that designates the percentage of water present in steam. This term is also used to denote the presence of water on a heating surface
WET STEAM
Steam that contains moisture.
WINDBOX
A chamber below the grate or surrounding a burner, through which air under pressure is supplied for combustion of the fuel.
WINDBOX PRESSURE
A burner or stoker’s static pressure as is present in its windbox.
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