Article Index

Circulation- The movement of water and steam within a steam generating unit.

Circulation ratio- The ratio of water entering a circuit to the steam generated by that passes that circuit in a unit of time.

Circulating tube- A Boiler tube used to connect water spaces of two drums or the pressure parts of a boiler.

Circulator- Pipe or tube for steam or water to pass between upper boiler drums usually located where the heat absorption is low. Circulator is also used to apply tubes connecting headers of horizontal water tube boilers to drums.

Closing-in-line- The sealing with plastic refractory between boiler shell or head and firebrick wall; is used to prevent hot gases from making contact to the boiler above the lowest waterline.

CO- Carbon monoxide.

CO2- Carbon dioxide.

Collector- Device used in the removal of gas solids from flue gas.

Colloid- Organic substance divided fine which tends to inhibit the formation of dense scale and results in deposition of sludge, can cause it to remain in suspension, then it may be blown from the boiler.

Combined feedwater cutoff- Regulating device for makeup boiler water combined with the low water fuel cut off.

Combustion loss- Loss representing the unliberated thermal energy caused by complete oxidation failure to some of the combustible matter in the fuel.

Combustibles- Constituents of a fuel that produce heat.

Combustion- When oxygen is combined with the combustible elements of a fuel and results in a rapid chemical combination that releases heat.

Combustion air- Out door fresh air that is brought in through a furnace duct and/or hot water heater.

Combustion chamber- See Furnace.

Combustion efficiency- The burner’s ability to completely burn the fuel effectively.

Complete combustion- The complete oxidation of all the combustible materials of a fuel.

Concentration- Abundance of a constituent that’s divided by the total volume of a mixture.

Condensate- The liquid phase produced by the condensation of steam or any other gas.

Conduction- Heat transmission through and by means of matter unaccompanied by any obvious motion of the matter.

Conductivity- Is the measure of the ease at which an electric charge or heat can pass through a material.

Continuous blowdown- Uninterrupted removal of concentrated water from a boiler in to control an amount of suspended solid concentration in the remaining water. Blowdown amount depends on the rate of evaporation and the amount of sludge that’s forming material in the feedwater.

Control- Any manual or automatic device that regulates a machine to keep it in normal operation. Automatic devices are driven by changes in temperature, pressure, water level, time, light, or other forces.

Control- A valve used to control air, gas, water, steam or other substance flows.

Control limit- Automatic safety control responding to changes in pressure, liquids or temperature levels that are set normally beyond the operating ranges to limit the operation of controlled equipment.

Control operate- A control that starts or regulates input according to demand and to stop or regulate input on satisfaction of demand. This is not an interlock or safety control.

Convection- The circulatory transfer motion of heat or mass by large fluid movements.

Convection section- Part of a furnace between the radiant and the stack, filled with tubes or pipes that carry process steam that absorb heat by convection heat transfer from the hot gases passing through the area on the way out of the stack.

Corrosion- It is the gradual destruction of metal materials by chemical reaction with their environment. Usually caused by the presence of O2, CO2, or an acid inside a boiler.

Corrosion fatigue- Fatigue in a corrosive environment. It is the mechanical degradation of a material under the joint action of corrosion and cyclic loading. Cracks can be produced by the combined action of repeated or fluctuating stress and a corrosive environment.

Crimping- Reducing the diameter of the end of a boiler tube to remove it to from a boiler.

Crown sheet- The upper sheet of the inner firebox boiler, the plate forming the top of the furnace.