coke (redirected from cokes)

coke, substance obtained by the destructive distillation of bituminous coal. Coke bears the same relation to coal as does charcoal to wood. A hard, gray, massive, porous fuel, coke is the solid residue remaining after bituminous coal is heated to a high temperature out of contact with air until substantially all components that easily vaporize have been driven off. The residue is chiefly carbon, with minor amounts of hydrogen, nitrogen, sulfur, and oxygen. Also present in coke is the mineral matter in the original coal, chemically altered and decomposed.

Since the vapor-producing constituents are driven off during coke production, coke is an ideal fuel for stoves and furnaces in which the environment is unsuitable for the complete burning of bituminous coal itself. In the form of oven coke it is primarily used when a porous fuel with few impurities and high carbon content is desired, as in the blast furnace to make iron. Coke is also used in other metallurgical processes, such as the manufacture of ferro-alloys, lead, and zinc, and in kilns to make lime and magnesium. Exceptionally large strong coke is known as foundry coke and is used in foundry cupolas to smelt iron ores. The smallest sizes of coke are used to heat buildings.

The majority of coke produced in the United States comes from byproduct coke ovens. The coke is prepared in retorts or furnaces of silica brick, and the byproducts (chiefly ammonia, coal tar, and gaseous compounds) are saved. These volatile gases are collected and sent to the byproduct plant where various byproducts are recovered. In nonrecovery coke plants, originally referred to as beehive ovens, the coal is carbonized in large oven chambers; the partially combusted gases collect in a common tunnel and exit via a stack. In recovery coke plants the waste gas exits into a waste heat recovery boiler which converts the excess heat into steam for power generation.

Petroleum coke is the solid residue left by the cracking process of oil refining. Natural coke, or carbonite, is formed by metamorphism from bituminous coal when intrusive igneous rock cuts across a vein of coal.

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coke

Solid residue remaining after certain types of coals are heated to a high temperature out of contact with air until substantially all components that easily vaporize have been driven off. The residue is chiefly carbon, with minor amounts of hydrogen, nitrogen, sulfur, and oxygen. Also present in coke is the mineral matter in the original coal, chemically altered and decomposed. The gradual exhaustion of timber in England had led first to prohibitions on cutting of wood for charcoal and eventually to the introduction of coke. Thereafter the iron industry expanded rapidly and Britain became the world's greatest iron producer (see Abraham Darby). The crucible process (1740) resulted in the first reliable steel made by a melting process. Oven coke (about 1.5–4 in., or 40–100 mm, in size) is used in blast furnaces to make iron. Smaller quantities of coke are used in other metallurgical processes (see metallurgy), such as the manufacture of certain alloys. Large, strong coke, known as foundry coke, is used in smelting. Smaller sizes of coke (0.6–1.2 in., or 15–30 mm) are used to heat buildings.

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coke

1. a solid-fuel product containing about 80 per cent of carbon produced by distillation of coal to drive off its volatile constituents: used as a fuel and in metallurgy as a reducing agent for converting metal oxides into metals

2. any similar material, such as the layer formed in the cylinders of a car engine by incomplete combustion of the fuel

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Coke

1. Sir Edward. 1552--1634, English jurist, noted for his defence of the common law against encroachment from the Crown: the Petition of Right (1628) was largely his work

2. Thomas William, 1st Earl of Leicester, known as Coke of Holkham. 1752--1842, English agriculturist: pioneered agricultural improvement and considerably improved productivity at his Holkham estate in Norfolk