A cyclone furnace is a type of

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

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, burner can, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion ...

commonly used in large industrial

boilers A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central ...

Background

Developed in the early 1942 by

Babcock & Wilcox Babcock & Wilcox Enterprises, Inc. is an American energy technology and service provider that is active and has operations in many international markets with its headquarters in Akron, Ohio. Historically, the company is best known for their stea ...

to take advantage of coal grades not suitable for pulverized coal combustion, cyclone furnaces feed coal in a spiral manner into a combustion chamber for maximum

combustion efficiency Combustion efficiency refers to the effectiveness of the burning process in converting fuel into heat energy. It is measured by the proportion of fuel that is efficiently burned and converted into useful heat, while minimizing the emissions of po ...

. During coal combustion in a furnace, volatile 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 In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between ...

to provide fresh air to surfaces of the coal particles. Cyclone furnaces were originally designed to take advantage of four things #Lower fuel preparation time and costs #Smaller more compact furnaces #Less

fly ash Coal combustion products (CCPs), also called coal combustion wastes (CCWs) or coal combustion residuals (CCRs), are byproducts of burning coal. They are categorized in four groups, each based on physical and chemical forms derived from coal combust ...

and convective pass slagging #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 to the outside of the tubes. The studs are coated with a refractory material, usually

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

based, that allows the cyclone to operate at a high enough temperature to keep the

slag The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be c ...

in a molten state and allow removal through the tap. 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 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, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the coal seam, ...

lignite coal Lignite (derived from Latin ''lignum'' meaning 'wood'), often referred to as brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35% and is considered the lowest ...

, mineral rich anthracitic coal,

wood chips Woodchips are small- to medium-sized pieces of wood formed by cutting or chipping larger pieces of wood such as trees, branches, logging residues, stumps, roots, and wood waste. Woodchips may be used as a biomass solid fuel and are raw materia ...

petroleum coke Petroleum coke, abbreviated coke, pet coke or petcoke, is a final carbon-rich solid material that derives from oil refinery, oil refining, and is one type of the group of fuels referred to as Coke (fuel), cokes. Petcoke is the coke that, in parti ...

, and old

tires A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over w ...

can and have all been used in cyclones. The crushed coal is fed into the cyclone burner and fired with high rates of heat release. Before the hot gases enter in the boiler furnace the combustion of coal is completed. The crushed coal is fed into cyclone burners. The coal is Burned by centrifugal action which is imparted by the primary air which enters tangentially and secondary Air which also enters in the top tangentially at high speed and tertiary air is admitted in the centre. Due to Whirling action of coal and air, a large amount of heat is generated (1500–1600 °C) and that covered the surface of cyclone and ashes are transformed into molten slag. The molten slag drained from the boiler furnace through a slag tap.

References

{{DEFAULTSORT:Cyclone Furnace Power station technology Boilers Energy conversion Industrial furnaces