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Glossary of TermsDefinitionsASTM — The American Society for Testing and Materials
Ash — The inorganic, non-combustible component in coal that remains after complete combustion has taken place. It has no heating value and typically is expressed in percent by weight.
Ash fusion temperatures — The ash of a coal is formed into a cone and heated under prescribed conditions in a testing laboratory. These temperature points are usually observed: Softening temperature — The temperature at which the ash cone has fused down to a spherical lump at which point the height is equal to the width of the base. Fluid temperature — The temperature at which the ash cone has fused down and spread out to nearly a flat layer at which point the maximum height is 1/16 inch.
Barrel (petroleum) — A unit of volume equal to 42 U.S. gallons.
British thermal unit (Btu) — The quantity of heat needed to raise the temperature of one pound of water by one degree F at or near 39.2 F.
BTU (as received) — An expression used to indicate the heating value of fuel in the condition the fuel is received at the location of consumption.
BTU (dry basis) — The method of reporting fuel analyses whereby the moisture is eliminated and the other constituents are recalculated to total 100 percent. BTU (dry, ash free/"daf") — The method of reporting fuel analyses whereby the moisture and ash are eliminated and the remaining constituents are recalculated to total 100 percent.
Bug dust — The coal fines resulting from cutting the coal seam with a machine. The term is sometimes used to indicate any small sized coal.
Coal — A brown-to-black, organic, combustible, sedimentary rock. It is formed through a progressive alteration known as coalification in which plant remains are physically and chemically altered by pressure, heat and time. Coals are classified by the degree of coalification. (See rank)
Cogenerator — A generating facility that produces electricity and other forms of useful thermal energy (such as heat or steam) used for industrial, commercial, heating and cooling purposes.
Coke — The solid carbonaceous residue produced by the thermal decomposition of coal. It is used both as a fuel and as a reducing agent in smelting iron ore in a blast furnace.
Coke breeze — The smallest fraction from the screening of coke; the residue that passes through a half-inch or three-quarter-inch screen opening.
Coke button (See FSI) — A button-shaped piece of coke resulting from a standard laboratory test that indicates the coking or free-swelling characteristics of coal. A coke button is usually expressed in numbers from one to nine. This represents the size of the coke as compared to a standard. The more a coal swells and cokes, the higher the number assigned to it.
Crude oil — Oil removed from the ground before it is processed.
Cubic foot (natural gas) — A unit of volume equal to 1 cubic foot at a pressure base of 14.73 pounds standard per square inch absolute and a temperature base of 60 F.
Dew point — The temperature at which condensation starts.
Distillate fuel oil — A general classification for one of the petroleum fractions produced in conventional distillation operations. Included are products known as No. 1, No. 2 and No. 4 fuel oils and No. 1, No. 2 and No. 4 diesel fuels. It is used primarily for space heating, on- and off-highway diesel engine fuel (including railroad engine fuel and fuel for agricultural machinery) and electric power generation.
Expansion/contraction — As coal is coked, it contracts and expands to a certain degree. The pressure exerted on oven walls due to expansion may be great enough to cause damage to the walls. The expansion/contraction properties can be determined in laboratory tests.
Fixed carbon — The solid combustible residue left after the moisture and volatile matter have been driven off by heating. In the proximate analysis, it is calculated by subtracting the sum of moisture, ash and volatile matter from 100 percent. (See proximate analysis)
Fluidity — As a coking coal is heated, it passes through a stage in which the coal becomes plastic or fluid. The properties of the coal during this stage (such as the temperature range or plasticity, and the temperature of maximum fluidity) can be determined by laboratory tests.
Fly ash — The fine particles of ash that are carried through the various passes in the furnace by the products of combustion and are usually collected in the last pass of boiler by a precipitator or dust collector.
Fossil fuel — Any naturally occurring organic fuel such as petroleum, coal and natural gas.
Free swelling index (FSI) — A measure of the tendency of a coal to swell when heated under controlled conditions. It is used as an indication of the caking characteristics of coal when burned as a fuel. It is not recommended for determining the expansion properties of coals in a coke oven.
Friability — The tendency of a coal to crumble or break into small pieces.
Fusibility — This test measures the temperatures at which coal ash softens and becomes fluid when heated according to prescribed conditions. (See ash fusion temperatures)
Gasohol — A blend of finished motor gasoline (leaded or unleaded) and alcohol (generally ethanol but sometimes methanol) limited to 10 percent by volume of alcohol. Gasohol is included in finished leaded and unleaded motor gasoline.
Grindability — (See Hardgrove Grindability Index)
Hardgrove Grindability Index (HGI) — A measurement of the relative ease of pulverizing a coal in comparison with a standard coal chosen as 100 grindability. The higher the grindability index, the easier the coal is to grind.
Hydroelectric power — The production of electricity from the kinetic energy of falling water.
Liquefied natural gas (LNG) — Natural gas (primarily methane) that has been liquefied by reducing its temperature to -260 F at atmospheric pressure.
Liquefied petroleum gases (LPG) — Ethane, ethylene, propane, propylene, normal butane, butylene and isobutane produced at refineries or natural gas processing plants, including plants that fractionate new natural gas plant liquids.
Liquefied refinery gases (LRG) — Liquefied petroleum gases fractionated from refinery or still gases. Through compression and/or refrigeration, they are retained in the liquid state. The reported categories are ethane/ethylene, propane/propylene, normal butane/butylene and isobutane. Excludes still gas.
Metallurgical coal — Coal that meets the requirements for making coke. It must be low in ash and sulfur and form a coke that is capable of supporting the charge of iron ore and limestone in a blast furnace.
Moisture —
Natural gas — A mixture of hydrocarbons (principally methane) and small quantities of various non-hydrocarbons existing in the gaseous phase or in solution with crude oil in underground reservoirs.
Non-caking coal — Coal that does not fuse together or cake when heated but burns freely.
Oxidized coal — When subject to continued weathering, some coals have a tendency to combine chemically with oxygen in the atmosphere more than others. When this takes place, coal loses some of its heating value. Low rank coals tend to oxidize at a faster rate than high rank coals. When oxidation takes place, coal takes on a brownish color and tends to lose its coking qualities.
Petroleum coke — A residue that is the final product of the condensation process in cracking. The product is either marketable petroleum coke or catalyst petroleum coke.
Proximate analysis — The determination of moisture, ash, volatile matter and fixed carbon by prescribed methods. Expressed in percentages by weight.
Rank — A classification of coal that indicates the degree of coalification or alteration from lignite to anthracite.
Reflectant — A measure of a coal's rank determined by the amount of light reflected from a sample under specified conditions and procedures.
Screenings — The undersized coal from a screening process, usually a half-inch or smaller.
Short ton (coal) — A unit of weight equal to 2,000 pounds.
Slack — Screenings of fine coal, usually a half-inch or smaller of bituminous coal.
Slag — As related to coal, ash that is or has been in a molten state.
Spontaneous combustion — An ignition caused by the accumulation of heat generated by the slow oxidation of coal in an air supply sufficient to support oxidation but insufficient to dissipate the heat. An example of where this can occur is a storage pile. The tendency of a coal to spontaneously combust or self-heat increases with increasing amounts of sulfur and moisture. Sulfur — Sulfur in coal usually occurs in three forms:
Surface mining — A method of mining that employs large equipment to remove the overburden (rock, dirt, etc.) thereby exposing the coal seam. Includes methods such as mountain-top removal, contour strip, area (or strip) mining and auger mining.
Synthetic natural gas (SNG) — A manufactured product chemically similar in most respects to natural gas, resulting from the conversion or reforming of petroleum hydrocarbons. It may easily be substituted for, or interchanged with, pipeline quality natural gas. Also referred to as substitute natural gas.
Ultimate analysis — The determination of carbon, hydrogen, nitrogen, oxygen, ash and sulfur. Expressed in percentages by weight.
Underground mining — Also called "deep mining." A method of mining in which the coal is extracted from beneath the earth's surface. Types of underground mines include drift, slope and shaft. Methods include room and pillar using conventional or continuous mining equipment, shortwall and longwall.
Volatile matter — The products, excluding moisture, that are given off in a gaseous or vaporous form when a coal is heated according to prescribed methods. Volatile matter is mainly composed of combustible gases. |
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