Cyclone furnace
Overview
 
A cyclone furnace is a type of coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 combustor
Combustor
A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, the combustor or combustion chamber is fed high pressure air by the compression system. The...

 commonly used in large industrial boilers.
Developed in the early 1942 by Babcock & Wilcox
Babcock and Wilcox
The Babcock & Wilcox Company is a U.S.-based company that provides design, engineering, manufacturing, construction and facilities management services to nuclear, renewable, fossil power, industrial and government customers worldwide. B&W's boilers supply more than 300,000 megawatts of installed...

 to take advantage of coal grades not suitable for pulverized coal combustion
Pulverized coal-fired boiler
A pulverized coal-fired boiler is an industrial or utility boiler that generates thermal energy by burning pulverized coal that is blown into the firebox....

, cyclone furnaces feed coal in a spiral manner into a combustion chamber for maximum combustion efficiency.
During coal combustion in a furnace, volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 components burn without much difficulty. Fuel carbon “char” particles (heavier, less volatile coal constituents) require much higher temperatures and a continuing supply of oxygen.
Encyclopedia
A cyclone furnace is a type of coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 combustor
Combustor
A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, combustion chamber or flame holder. In a gas turbine engine, the combustor or combustion chamber is fed high pressure air by the compression system. The...

 commonly used in large industrial boilers.

Background

Developed in the early 1942 by Babcock & Wilcox
Babcock and Wilcox
The Babcock & Wilcox Company is a U.S.-based company that provides design, engineering, manufacturing, construction and facilities management services to nuclear, renewable, fossil power, industrial and government customers worldwide. B&W's boilers supply more than 300,000 megawatts of installed...

 to take advantage of coal grades not suitable for pulverized coal combustion
Pulverized coal-fired boiler
A pulverized coal-fired boiler is an industrial or utility boiler that generates thermal energy by burning pulverized coal that is blown into the firebox....

, cyclone furnaces feed coal in a spiral manner into a combustion chamber for maximum combustion efficiency.
During coal combustion in a furnace, volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 components burn without much difficulty. Fuel carbon “char” particles (heavier, less volatile coal constituents) require much higher temperatures and a continuing supply of oxygen. Cyclone furnaces are able to provide a thorough mixing of coal particles and air with sufficient turbulence
Turbulence
In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...

 to provide fresh air to surfaces of the coal particles.

Cyclone furnaces were originally designed to take advantage of four things
  1. Lower fuel preparation time and costs
  2. Smaller more compact furnaces
  3. Less fly ash and convective pass slagging
  4. Flexibility in fuel types

Operation

A cyclone furnace consists of a horizontal cylindrical barrel attached through the side of a boiler furnace. The cyclone barrel is constructed with water cooled, tangential oriented, tube construction. Inside the cyclone barrel are short, densely spaced, pin studs welded
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

 to the outside of the tubes. The studs are coated with a refractory material
Refractory
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above...

, usually silica or aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 based, that allows the cyclone to operate at a high enough temperature to keep the slag
Slag
Slag is a partially vitreous by-product of smelting ore to separate the metal fraction from the unwanted fraction. It can usually be considered to be a mixture of metal oxides and silicon dioxide. However, slags can contain metal sulfides and metal atoms in the elemental form...

 in a molten state and allow removal through the trap.

Crushed coal and a small amount of primary air enter from the front of the cyclone into the burner. In the main cyclone burner, secondary air is introduced tangentially, causing a circulating gas flow pattern. The products, flue gas and un-combusted fuel, then leave the burner and pass over the boiler tubes. Tertiary air is then released further downstream to complete combustion of the remaining fuel, greatly reducing NOx
NOx
NOx is a generic term for the mono-nitrogen oxides NO and NO2 . They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures...

 formation. A layer of molten slag coats the burner and flows through traps at the bottom of the burners, reducing the amount of slag that would otherwise form on the boiler tubes.

Cyclone Furnaces can handle a wide range of fuels. Low volatile bituminous coal
Bituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...

s, lignite coal
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

, mineral rich anthracitic coal, wood chips
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...

, petroleum coke
Petroleum coke
Petroleum coke is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Other coke has traditionally been derived from coal....

, and old tires can and have all been used in cyclones.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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