Coke (fuel)

Coke (fuel)

Overview
Coke is the solid carbonaceous
Carbonaceous
Carbonaceous is the defining attribute of a substance rich in carbon. Particularly, carbonaceous hydrocarbons are very unsaturated, high-molecular-weight hydrocarbons, having an elevated carbon:hydrogen ratio....

 material derived from destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 of low-ash, low-sulfur 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...

. Cokes from 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...

 are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.


The Chinese first used coke for heating and cooking no later than the ninth century AD. By the first decades of the eleventh century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke, solving their fuel problem in that tree-sparse region.

In 1603, Hugh Plat
Hugh Plat
-Life:He was baptised at St. James's, Garlickhythe, on 3 May 1552, he was third son of Richard Plat or Platt, a London brewer; his father owned property in St. Pancras, London, bequeathed much of it to the foundation and endowment of a free school and six almshouses at Aldenham, Hertfordshire, and...

 suggested that coal might be charred in a manner analogous to the way charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 is produced from wood.
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Encyclopedia
Coke is the solid carbonaceous
Carbonaceous
Carbonaceous is the defining attribute of a substance rich in carbon. Particularly, carbonaceous hydrocarbons are very unsaturated, high-molecular-weight hydrocarbons, having an elevated carbon:hydrogen ratio....

 material derived from destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents,...

 of low-ash, low-sulfur 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...

. Cokes from 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...

 are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.

History



The Chinese first used coke for heating and cooking no later than the ninth century AD. By the first decades of the eleventh century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke, solving their fuel problem in that tree-sparse region.

In 1603, Hugh Plat
Hugh Plat
-Life:He was baptised at St. James's, Garlickhythe, on 3 May 1552, he was third son of Richard Plat or Platt, a London brewer; his father owned property in St. Pancras, London, bequeathed much of it to the foundation and endowment of a free school and six almshouses at Aldenham, Hertfordshire, and...

 suggested that coal might be charred in a manner analogous to the way charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 is produced from wood. This process was not put into practice until 1642, when coke was used for roasting malt
Malt
Malt is germinated cereal grains that have been dried in a process known as "malting". The grains are made to germinate by soaking in water, and are then halted from germinating further by drying with hot air...

 in Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...

. Coal cannot be used in brewing because its sulfurous fumes would impart a foul taste to the beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...

.

In 1709, Abraham Darby I
Abraham Darby I
Abraham Darby I was the first, and most famous, of three generations with that name in an English Quaker family that played an important role in the Industrial Revolution. He developed a method of producing pig iron in a blast furnace fuelled by coke rather than charcoal...

 established a coke-fired blast furnace
Blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...

 to produce cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

. Coke's superior crushing strength allowed blast furnaces to become taller and larger. The ensuing availability of inexpensive iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 was one of the factors leading to the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

.

In England in the first years of steam railway locomotives, coke was the normal fuel. This resulted from an early piece of environmental legislation; any proposed locomotive had to "consume its own smoke". This was not technically possible to achieve until the firebox arch came into use, but burning coke, with its low smoke emissions, was considered to meet the requirement. However, this rule was quietly dropped and cheaper coal became the normal fuel, as railways gained acceptance among the general public.

In the late 19th century, the coalfield
Coalfield
A coalfield is an area of certain uniform characteristics where coal is mined. The criteria for determining the approximate boundary of a coalfield are geographical and cultural, in addition to geological...

s of western Pennsylvania
Western Pennsylvania
Western Pennsylvania consists of the western third of the state of Pennsylvania in the United States. Pittsburgh is the largest city in the region, with a metropolitan area population of about 2.4 million people, and serves as its economic and cultural center. Erie, Altoona, and Johnstown are its...

 provided a rich source of raw material for coking. In 1885, the Rochester and Pittsburgh Coal and Iron Company constructed the world's longest string of coke ovens in Walston, Pennsylvania, with 475 ovens over a length of one and a quarter miles. Their output reached 22,000 tons per month. The Minersville Coke Ovens
Minersville Coke Ovens
Minersville Coke Ovens is a historic set of coke oven site located at Carbon Township in Huntingdon County, Pennsylvania. The property includes the remains of beehive and Mitchell coke ovens, the pillars and remains of the tipple, the foundation remains of the supply house, engine and power house,...

 in Huntingdon County, Pennsylvania
Huntingdon County, Pennsylvania
Huntingdon County is a county located in the U.S. state of Pennsylvania. In 2010, its population was 45,913.Huntingdon County was created on September 20, 1787, from part of Bedford County. Its county seat is Huntingdon.-Geography:According to the U.S...

 were listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...

 in 1990.

Production




Volatile constituents of the 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...

—including water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

, coal-gas, and coal-tar—are driven off by baking in an airless furnace or oven at temperatures as high as 2,000 degrees Celsius (3632 degrees Fahrenheit). This fuses together the fixed carbon
Carbon fixation
In biology, carbon fixation is the reduction of carbon dioxide to organic compounds by living organisms. The obvious example is photosynthesis. Carbon fixation requires both a source of energy such as sunlight, and an electron donor such as water. All life depends on fixed carbon. Organisms that...

 and residual ash. Most modern facilities have "by-product" coking ovens. Today, the volatile hydrocarbons are mainly used, after purification, in a separate combustion process to generate energy. Non by-product coking furnaces or coke furnaces (ovens) burn the hydrocarbon gases produced by the coke-making process to drive the carbonization
Carbonization
Carbonization or carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal...

 process.

Bituminous coal must meet a set of criteria for use as coking coal, determined by particular coal assay
Coal assay
Coal Analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.-Chemical...

 techniques. These include moisture content, ash content, sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 content, volatile content, tar
Tar
Tar is modified pitch produced primarily from the wood and roots of pine by destructive distillation under pyrolysis. Production and trade in tar was a major contributor in the economies of Northern Europe and Colonial America. Its main use was in preserving wooden vessels against rot. The largest...

, and plasticity
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the...

. This blending is targeted at producing a coke of appropriate strength (generally measured by coke strength after reaction
Coke strength after reaction
Coke Strength after Reaction refers to coke "hot" strength, generally a quality reference in a simulated reaction condition in an industrial blast furnace. The test is based on a procedure developed by Nippon Steel Corp in the 1970s as an attempt to get an indication of coke performance and is...

 (CSR), while losing an appropriate amount of mass. Other blending considerations include ensuring the coke doesn't swell too much during production and destroy the coke oven through excessive wall pressures.

The greater the volatile matter in coal, the more by-product can be produced. It is generally considered that levels of 26-29 percent of volatile matter in the coal blend are good for coking purposes. Thus different types of coal are proportionally blended to reach acceptable levels of volatility before the coking process begins.

Natural coke is formed when a coal seam is intersected by a volcanic intrusion. These intrusions heat the surrounding coal in an anoxic atmosphere producing coke in a zone (usually several meters) around the intrusion. However, the coke is of wildly varying strength and ash content and is generally considered unsaleable except in some cases as a thermal product—as it has lost its volatile matter it has lost the ability to be coked again.

Uses


Coke is used as a fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 and as a reducing agent
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

 in smelting
Smelting
Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction from iron ore, and copper extraction and other base metals from their ores...

 iron ore in a blast furnace
Blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...

. It is there to reduce the iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...

 (haematite) in order to collect iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

.

Since smoke
Smoke
Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires , but may also be used for pest...

-producing constituents are driven off during the coking of coal, coke forms a desirable fuel for stove
Stove
A stove is an enclosed heated space. The term is commonly taken to mean an enclosed space in which fuel is burned to provide heating, either to heat the space in which the stove is situated or to heat the stove itself, and items placed on it...

s and furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...

s in which conditions are not suitable for the complete burning of 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...

 itself. Coke may be burned with little or no smoke under combustion conditions, while bituminous coal would produce much smoke.

Discovered by accident to have superior heat shield
Heat shield
A heat shield is designed to shield a substance from absorbing excessive heat from an outside source by either dissipating, reflecting or simply absorbing the heat...

ing properties when combined with other materials, coke was one of the materials used in the heat shielding on NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Apollo program space vehicles. In its final form, this material was called AVCOAT 5026-39
AVCOAT 5026-39
AVCOAT 5026-39 is a NASA code for a specific ablative heat shield created by Avco .It is an epoxy novolac resin with special additives in a fiberglass honeycomb matrix...

. This material has been used most recently as the heat shielding on the Mars Pathfinder
Mars Pathfinder
Mars Pathfinder was an American spacecraft that landed a base station with roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight wheeled robotic rover named Sojourner.Launched on December 4, 1996 by NASA aboard a Delta II booster a...

 vehicle. Although not used for modern day space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

s, NASA had been planning to utilize coke and other materials for the heat shield for its next generation space craft, named Orion
Orion (spacecraft)
Orion is a spacecraft designed by Lockheed Martin for NASA, the space agency of the United States. Orion development began in 2005 as part of the Constellation program, where Orion would fulfill the function of a Crew Exploration Vehicle....

, before that project's cancellation.

Coke was widely used as a substitute for coal in domestic heating following the creation of Smokeless zones in the United Kingdom when the government paid for new grates suitable for the fuel. Ironically the grates required the use of a gas fired poker to light the fuel so the new installation included installation of a gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

 line adjacent to the fireplace. Most consumers converted to a gas fire designed to work with an existing chimney within a few years.

Highland Park
Highland Park Single Malt
Highland Park Single Malt is a Scotch whisky distilled by Highland Park Distillery, Kirkwall in Orkney, the most northerly whisky distillery in Scotland, half a mile north of that at Scapa. Blackwood Distillery in Shetland presently produces only gin and vodka .Highland Park has performed well at...

 distillery in Orkney malt barley for use in their Scotch
Scotch whisky
Scotch whisky is whisky made in Scotland.Scotch whisky is divided into five distinct categories: Single Malt Scotch Whisky, Single Grain Scotch Whisky, Blended Malt Scotch Whisky , Blended Grain Scotch Whisky, and Blended Scotch Whisky.All Scotch whisky must be aged in oak barrels for at least three...

 whisky
Whisky
Whisky or whiskey is a type of distilled alcoholic beverage made from fermented grain mash. Different grains are used for different varieties, including barley, malted barley, rye, malted rye, wheat, and corn...

 in kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...

s burning a mixture of coke and peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

. The peat is burned for the initial stage of roasting the barley - while the barley can still absorb the particular desired aromas of the peat - lasting for approximately 12 hours; then for the final 36 hours the barley is roasted under the heat of the burning coke.

Gas byproducts


Coke may be used to make synthesis gas, a mixture of carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

.
  • Syngas
    Syngas
    Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

    ; Water gas
    Water gas
    Water gas is a synthesis gas, containing carbon monoxide and hydrogen. It is a useful product but requires careful handling because of the risk of carbon monoxide poisoning. The gas is made by passing steam over a red-hot hydrocarbon fuel such as coke:...

    : a mixture of carbon monoxide
    Carbon monoxide
    Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

     and hydrogen
    Hydrogen
    Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

    , made by passing steam over red-hot coke (or any carbon based char)
  • Producer gas
    Producer gas
    -USA:Producer Gas is a generic term referring to:* Wood gas: produced in a gasifier to power cars with ordinary internal combustion engines.* Town gas: manufactured gas, originally produced from coal, for sale to consumers and municipalities....

    ; wood gas
    Wood gas
    Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of petrol, diesel or other fuels. During the production process biomass or other carbon-containing materials is gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen...

    ; generator gas; synthetic gas; suction gas: a mixture of carbon monoxide
    Carbon monoxide
    Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

    , hydrogen
    Hydrogen
    Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

     and nitrogen
    Nitrogen
    Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

    , made by passing air over red-hot coke (or any carbon based char)

Properties



The bulk specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 of coke is typically around 0.77. It is highly porous.

The most important properties of coke are ash and sulfur content, which are linearly dependent on the coal used for production. Coke with less ash and sulfur content is highly priced on the market. Other important characteristics are the M10, M25, and M40 test crush indexes, which convey the strength of coke during transportation into the blast furnaces; depending on blast furnaces size, finely crushed coke pieces must not be allowed into the blast furnaces because they would impede gas dynamics. A related characteristic is the Coke strength after reaction
Coke strength after reaction
Coke Strength after Reaction refers to coke "hot" strength, generally a quality reference in a simulated reaction condition in an industrial blast furnace. The test is based on a procedure developed by Nippon Steel Corp in the 1970s as an attempt to get an indication of coke performance and is...

 (CSR) index; it represents coke's ability to withstand the violent conditions inside the blast furnace before turning into fine particles.

The water content in coke is practically zero at the end of the coking process, but coke is often water quenched to reduce its temperature so that it can be transported inside the blast furnaces. The porous structure of coke absorbs some water, usually 3-6 % of its mass. In some more modern coke plants an advanced method of coke cooling is by air quenching.

Bituminous coal must meet a set of criteria for use as coking coal, determined by particular coal assay
Coal assay
Coal Analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.-Chemical...

 techniques. See Section "Production".

The volatility of coke reaches minimum levels at the end of the coking process.

Other processes



The solid residue remaining from refinement of petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 by the "cracking
Cracking (chemistry)
In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products...

" process is also a form of coke. 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....

 has many uses besides being a fuel, such as the manufacture of dry cell
Dry Cell
-Dry Cell's formation:Part of the band formed in 1998 when guitarist Danny Hartwell and drummer Brandon Brown met at the Ratt Show on the Sunset Strip. They later met up with then-vocalist Judd Gruenbaum. The original name of the band was "Beyond Control"....

s and electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

s. Gas works manufacturing syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

 also produce coke as an end product, called gas house coke.

Fluid coking is a process which converts heavy residual crude into lighter products such as naphtha
Naphtha
Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e., a component of natural gas condensate or a distillation product from petroleum, coal tar or peat boiling in a certain range and containing certain hydrocarbons. It is a broad term covering among the...

, kerosene
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

, heating oil
Heating oil
Heating oil, or oil heat, is a low viscosity, flammable liquid petroleum product used as a fuel for furnaces or boilers in buildings. Home heating oil is often abbreviated as HHO...

, and hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

gases. The "fluid" term refers to the fact that coke particles are in a continuous system versus older batch-coking technology.