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The process of rubbing, grinding or wearing away by friction.

Absolute pressure

Pressure above conditions of a perfect vacuum or zero pressure.


Tower absorbers, or a column, were gases or vapors are brought into intimate contact with a heavy absorbing liquid in which the vapors are to be retained. The absorbing fluid is sprayed from the top of the tower to that its extended surface permits the gases or vapors to enter the solution more quickly. The tower is usually packed with inert material (rings) or contains either sieve or bubble cap trays.


An operation where a soluble component of a gas stream is dissolved in a liquid.


A vertical or horizontal drum utilized to accumulate liquid so a sure supply of stock is available at a pump suction, or to a lower pressure vessel.


A chemical compound whose molecular structure includes one or more atoms of hydrogen which, on contact with certain metals, with certain compounds of these metals, or with some organic compounds, may be replaced by a quantity of the metal or by a hydrocarbon group, liberating hydrogen gas or forming water or a salt. An acid turns a blue litmus solution red.

Activated sludge

An aerobic biological process for conversion of soluble organic matter to solid biomass, removable by gravity or filtration.


A measure of the effectiveness of a catalyst for speeding up a chemical reaction. A catalyst with high activity is more effective than a catalyst with low activity. In general, catalyst activity decreases with catalyst age, so that older catalysts are less active than new catalysts.


Device which accepts the output from a control system and moves a final control element (usually a value) to change a process condition.

Adaptive control

Method of control whereby tuning (response) of the control system is varied with process condition, unlike other control systems where response times are set manually and remain constant.


Physical adhesion of molecules or colloids to the surfaces of solids without chemical reaction.

Aerobic organism

An organism that require oxygen for its metabolic processes.


A colloidal system involving liquid or solid particulates dispersed in air.

After cooler

A heat exchanger in which a stream is cooled, usually by water. Often used to describe the exchanger on a compressor discharge system.


To gather fine particles together into a larger mass.


An apparatus for mixing fluids and/or solids either by mechanical stirring or by forcing a number of jets of compressed air or steam into the mixture.

Air compressor

A machine designed for pumping air from a lower pressure to a higher pressure.

Air separation

A standard cryogenic technology liquefies air and separates it into its main constituents of oxygen, nitrogen and krypton-xenon. Oxygen is used in gasification. Nitrogen is used for other process and purging requirements. Nitrogen and krypton-xenon are sold as byproducts.


A group of organic compounds containing a hydroxyl group.


Simple plants containing chlorophyll. Many are microscopic, but under conditions favorable for their growth, they grow in colonies and produce mats and similar nuisance masses.


A chemical compound capable of neutralizing an acid.


By definition, total alkalinity (also called "M" alkalinity) is that which will react with acid as the pH of the sample is reduced to the methyl orange endpoint-about pH 4.2. Another significant expression is "P" alkalinity, which reacts with acid as the pH of the sample is reduced to 8.2.


Having the properties of an alkali; opposite to acidic. Total alkalinity (also called "M" alkalinity) is that which will react with acid as the pH of the sample is reduced to the methyl orange endpoint – about pH 4.2. Another significant expression is "P" alkalinity, which exists above pH 8.2 and is that which reacts with acid as the pH of the sample is reduced to 8.2.


A colorless, pungent, gaseous compound of nitrogen and hydrogen, possessing strong alkaline properties when in solution. It is soluble in water to an unusual degree, one part of water absorbing 600 parts of the gas. It is used as a refrigeration gas because of the ease with which it is liquefied at moderately low temperatures by means of high pressure.

Ammonia recovery

Ammonia in the gas liquor is absorbed by an aqueous solution of diammonium phosphate. Ammonia is recovered from the phosphate solution and purified to a high-grade anhydrous ammonia.

Ammonia sulfide water

A stream containing water, H2S and NH3.

Ammonium sulfate

Granular fertilizer used for direct application to crop land.

Anaerobic organism

An organism that thrives in the absence of oxygen, and dies in the presence of oxygen.


Of or relating to data in the form of measureable quantities, such as millivolts or milliamps.


Devoid of water.

Anhydrous ammonia

Fertilizer used for direct application to crop land.

Anhydrous ammonia plant

Part of the gas stream is diverted here to produce anhydrous ammonia.

Antelope Valley Station (AVS)

Basin Electric’s two-unit, coal-based generating station that has a 900-megawatt capacity. AVS is located near Beulah, ND, and shares resources and facilities with Dakota Gasification Company’s Synfuels Plant.

Anti-foam additive

An additive which suppresses foaming.


To protect against surge in a compressor by recycling gas from the discharge to suction to always stay above the minimum flow requirements of the machine.

Arc welding

A group of welding processes that produce coalescence of metals by heating them with an arc, with or without the application of pressure of the use of filler metal.

Aromatic ring

A cyclic structure containing carbon atoms (usually six) equally spaced. There are no double bonds in aromatic rings. The simplest representative compound is benzene.

Atmospheric pressure

The pressure of the air on a body, which is exerted equally in all directions. It is equivalent to about 14.7 pounds per square inch at sea level.

Atmospheric tower

A column which is operated at or near atmospheric pressure.


The smallest unit of an element.

Atomizer (fuel oil atomizer)

A nozzle device used to break up fuel oil into a fine spray so the oil may be brought into more intimate contact with the air in the combustion chamber. The combustion will be more efficient and rapid than with a solid stream of oil. The atomization may be caused by forcing oil under high pressure through a whirling, perforated nozzle tip, or by directing the stream against a jet of air or steam.

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Microscopic single-cell plants which reproduce by fission or by spores, identified by their shapes: coccus, spherical, bacillus, rod-shaped; and spirillum, curved.


An air cleaning device consisting of one or many bag shaped fabric filters. Dirty air passes through the bag. When the filter plugs with solids, air is blown through the bag, dislodging solids from the bag. Solids fall to the bottom of the baghouse and are removed.

Basin Cooperative Services (BCS)

A not-for-profit subsidiary of Basin Electric since 1981 that acquires resources and services for electric plant generation.

Basin Telecommunications Inc. (BTInet)

A for-profit subsidiary of Basin Electric that offers commercial Internet service and Internet-based business solutions.


Billion cubic feet.


Catalyst or filter media contained in a vessel.

Blanket gas

Gas introduced above a liquid or slid in a vessel to keep out air to prevent oxidation of the material, or to prevent foaming or explosive mixtures.


To depressure or drain a line.


The process of reducing gas pressure by releasing such pressure to the atmosphere. Withdrawal of water from boilers and cooling towers to prevent buildup or high concentration of unwanted material.

Boiler feed water

Condensate and make up demineralized water, deaerated and inhibited for corrosion control and scaling.

Bosman’s skirt

Gasifier internals which replace the mechanical coal distributor. It is a tube extending downward from the coal lock. Coal flows down the skirt, gas collects in the annular space between the skirt and the gasifier jacket.

British Thermal Unit (Btu)

A measure of heat value. One Btu is the quantity of heat energy required to cause a pound of pure water to rise in temperature one degree Fahrenheit at or near its point of maximum density (39.1 degrees Fahrenheit). On average, there are approximately 1,000 Btu in a cubic foot of natural gas.


Useful materials recovered incidental to the principal objective of gasification.

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A compound of carbon with one or more metallic elements.


A chemical element occurring in the natural state as diamond, graphite or black lead; also, in compounds forming coal, petroleum, asphalt, limestone, other minerals, and all organic compounds. Its importance is largely due to its ability to form long series of complex compounds of chain-like or ring-like molecular structure with other elements. Its chemical symbol is C, its atomic weight is 12, and its specific gravity varies from 1.7 to 3.6.

Carbon capture and storage (CCS)

The technical process of separating carbon dioxide gas from power plant emissions (primarily coal- or natural gas-fired generation); compressing it; pumping it down into spent oil and natural gas wells, saline reservoirs, or inaccessible coal seams; and entombing it there forever.

Carbon dioxide

A colorless gas that makes up about 0.03 percent of the atmosphere. Also, a byproduct of the Synfuels Plant.


The conversion of an organic compound into char or coke by heating in the absence of air.

Carbon sequestration

The permanent removal of carbon dioxide from (or before it enters) the atmosphere by both natural (crops, forests, oceans, soil, and vegetation) and man-made means. Synonymous with the "storage" part of carbon capture and storage.


A material which increases the rate of a chemical reaction but does not react itself.

Cathodic protection

A method employing electrolysis to control corrosion or deterioration of steel pipe and connected metallic equipment.


A rotating instrument for separating liquids or liquids and solids of different specific gravity by use of centrifugal force. The heavier liquids will have the greater tendency to fly away from the center, and hence will be driven to the outer portions of the centrifuge casing.


An apparatus for analyzing mixtures of compounds by separating them into individual compounds which can be indentified by color or other means.


Coal ash which has melted and solidified in large chunks.

Coal gasification

The conversion of coal into methane, carbon oxides and other related compounds by the addition of steam and oxygen under high temperature and pressure.

Cold Box

Insulated container in the oxygen plant in which cryogenic separation of N2 and O2 is performed.


A chemical combination of two or more elements having specific identifying characteristics; it may be separated into its component parts only by chemical means.

Compressed natural gas (CNG)

Natural gas which is comprised primarily of methane, compressed to a pressure at or above 2,400 pounds per square inch and stored in special high-pressure containers. It is used as a fuel for natural gas powered vehicles.


A mechanical device which draws in gas, compresses it and discharges it at a higher pressure.


The process of increasing the dissolved solids per unit volume or solution usually by evaporation of the liquid; also, the amount of material dissolved in a unit volume of solution.


The liquid resulting when a vapor is subjected to cooling and pressure reduction. The condensable portion or the part of a vapor which has been condensed to the liquid state. For purposes of this manual, condensed steam.


An apparatus for liquefying vapors by cooling them to a temperature below their normal boiling point. The principle employed is that of conducting away the heat absorbed from the vapors through a cooling medium; e.g., of air, water, or some other liquid.


The flow of heat through a solid.


To program the control system interconnections and controller algorithms.


Device which receives a measurement of the process variable, compares that measurement with another representing the desired control point, and adjusts its output based on the selected control algorithm to minimize error between the two measurements.


The transfer and diffusion of heat by its absorption in the particles of matter which are in constant movement about the heat-producing body.


The degree of formation of products from feeds in a chemical reaction. For example, in shift conversion, the products are hydrogen and carbon dioxide; the feeds are carbon monoxide and steam. Changes in the amount of a feed, the process conditions, or catalyst activity changes the amount of conversion from feed to products.


A heat exchanger in which a process stream passes through pipes immersed in water to obtain a cooling effect on the stream.

Cooling tower water

Water circulated for process heat removal and cooled by passing through (over) a cooling tower. Treated to inhibit corrosion and algae growth.


The eating away of a metal surface as a result of a chemical reaction. It is usually caused by acidic materials; for example, acid gas (CO2 and H2S) corrosion may be a problem.

Coteau Freedom Mine

Coal mine adjacent to Synfuels Plant that supplies coal to facility.


The breaking down of a hydrocarbon molecule into two or more smaller molecules, or elements, by the use of heat, pressure and catalyst.

Cresylic acid

A flammable, colorless, yellowish, brownish-yellow or pinkish oily liquid used in antioxidants, pesticides, lubricants and plastics. It is a Synfuels Plant byproduct.

Cyclone Separator

Equipment used to separate entrained liquid or solid from gases. The gases enter the separator tangentially. Entrained particulates strike the circumference of the separator and fall to the bottom. Gases exit from the top.

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Dakota Coal Company (Dakota Coal or DCC)

A wholly owned for-profit subsidiary of Basin Electric formed in 1988 to provide financing for and market lignite from the Freedom Mine near Beulah, ND. The Freedom Mine supplies lignite for Dakota Gasification Company and Basin Electric’s Antelope Valley and Leland Olds stations. It has a division and a subsidiary. (See Montana Limestone Company and Wyoming Lime Producers.)

Dakota Gasification Company (DGC)

A wholly owned, for-profit subsidiary of Basin Electric founded in 1988 to own and operate the Great Plains Synfuels Plant near Beulah, ND. The plant produces natural gas from coal and byproducts of the coal gasification process.


Separation of entrained liquids out of the gas stream by chemical or adsorption methods to produce a relatively dry gas.


A unit of heating value equivalent to 10 therms or 1,000,000 Btu.


Any process used to remove minerals from water; however, commonly the term is restricted to ion exchange processes.


The weight of a given volume or a substance, usually expressed as pounds per cubic feet or grams per cubic centimeter.

Dew Point

Temperature at which a mixture of gases reaches saturation conditions for one or more of the components and condensation begins.


A program contained within a control system to troubleshoot itself.


A separation process depending on differences in diffusion rates of solutes across a permeable membrane.

Differential pressure

The pressure difference between to points.


Application of energy or chemicals to kill pathogenic organisms.


A liquid that has been vaporized and subsequently condensed in a container entirely apart from the vessel holding the unvaporized residue.


Vaporizing a liquid and subsequently condensing it in a different chamber. The separation of one constituent from another by means of volatilization in some form of closed apparatus, such as a still, by the aid of directly or indirectly applied heat. The vaporization of distinct groups of hydrocarbons takes place over different temperature ranges, so that by maintaining the fractionating tower at successively increasing temperature levels from the top down, the various groups of constituents evaporate away from the less volatile groups and are condensed and run into segregated tanks.


A mechanical device for distributing liquid flow evenly over tower packing or filter material.


Equipment charged with substances which will absorb or adsorb moisture from gas, or equipment which dries material with use of heat.


Water lost from a water cooling tower as liquid droplets entrained in the exhaust air. Units: pounds per hour or percent of circulating water flow.

Drift eliminator

Baffling installed in a cooling tower to remove entrained water droplets from the air stream.

Dry Fork Mine

Dry Fork Mine was developed to be a fuel supply source for the Laramie River Station (LRS). Dry Fork is a 7,000-acre mine located five miles northeast of Gillette. Three million tons of coal per year is shipped by rail to LRS near Wheatland, WY, which is approximately 100 miles from Dry Fork. Western Fuels Association operates the mine through its affiliates. Basin Electric is a member of Western Fuels.

Dry Fork Station

Projected to be operational by 2011, Basin Electric is constructing the Dry Fork Station, a coal-based power plant in the Gillette, WY, area to meet the growing electricity demand by its member systems. Dry Fork Station will have a 385-megawatt generating capacity.

Dry gas

The total of all components in a gas mixture except water (steam).

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A heat exchanger in a furnace stack that transfers heat from the stack gas to the boiler feedwater.


Liquid flowing from or leaving a process unit.


A substance that dissociates into two or more ions when dissolved in water, and allows the passage of an electric current.

Electrostatic precipitator

A device to remove entrained particles from a gas stream by electrically charging the particles and attracting them to oppositely charged collecting surfaces.


A substance which cannot be broken down into a simpler form; cannot be decomposed by ordinary chemical means.


A dispersion of fine particles of one liquid in another. A liquid dispersed in a normally immiscible liquid, such as oil in water. Emulsions do not separate well, and may cause problems in gas liquor separation.


A substance produced by living cells having the ability to reduce large organic molecules to units small enough to diffuse through the cell membrane.


The process of making things equal. Minimization of variations in flow and composition by means of a storage reservoir.


As used here, it means "equilibrium mixture." This is a mixture of components (feeds and products) of a reversible reaction. The components of an equilibrium mixture are always the same quantities of feeds at the same temperature and pressure. Changing one of these (e.g., adding an excess of steam) shifts the equilibrium.

Equivalent weight

The weight in grams of a substance which combines with or displaces one gram of hydrogen; usually obtained by dividing the formula weight by the valence.


Destruction of materials by the abrasive action of moving fluids, usually accelerated by the presence of solid particles or matter in suspension.


A vessel in which separation into liquid and vapor occurs, by applying heat.


One of the products of a solvent extraction operation. The extract is that portion of the feed which is dissolved in the solvent.

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Federal Energy Regulatory Commission (FERC)

An agency of the government of the United States created by an Act of Congress, the Department of Energy Organization Act, in 1977. This Act transferred to the FERC most of the former Federal Power Commission’s interstate regulatory functions over the electric power and natural gas industries.


The process of separating solids from a liquid by means of a porous substance through which only the liquid passes.


A high stack with a pilot flame used to burn excessive or waste gases. Also to allow the controlled burning of gases caused by overpressuring a vessel to the point where the relief valve opens.


The portion of a superheated fluid converted to vapor when its pressure is reduced.


A passage for air, gas or smoke.

Flue gas

Gas in the flue or stack of a furnace which results from burning the fuel in the furnace.

Flue gas desulfurization

This scrubber removes up to 97 percent of the sulfur dioxide emissions from the main stack’s flue gases. Because anhydrous ammonia is used as the reagent, this unique facility produces a valuable fertilizer, ammonium sulfate, instead of a waste product.


Easily crumbled or pulverized.


An aerosol with solids as the dispersed colloids.


That portion of a refinery heater that contains the firing equipment.

Freedom Mine

Located north of Beulah, ND, it is owned and operated by The Coteau Properties Company, a wholly owned subsidiary of The North American Coal Corporation. Dakota Coal Company provides financing for and markets the lignite from the Freedom Mine.

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Gas compression

Clean gas is cooled, dried and compressed into a pipeline leading to market.

Gas cooling

Converted gas and raw gas are cooled before purification in Rectisol.

Gas detector

An instrument for determining the explosivity of a gas-air mixture. It is used as a safety device in refinery operations and it is also known as an explosimeter.


A group of processes that turn coal into combustible gas by breaking apart the coal using heat and pressure and, in many cases, with hot steam.


Intense heat from combustion in gasifier vessels breaks the molecular structure of the coal and releases compounds to form the raw gas stream. There are 14 gasifier vessels.

Gas liquor

Primarily water which has been used to scrub the gasifier raw gas stream and contains tars, oils, ammonia, phenol and dust.

Gas liquor separation

The gas liquor stream contains tar, tar oils, phenols, ammonia and dissolved gases such as carbon dioxide and hydrogen sulfide.

Gauge pressure

Pressure above existing atmospheric pressure. (Atmospheric pressure is about 14.7 PSI at sea level).


The specific gravity or density relative to water.

Glenharold Mine

Lignite mine owned by Basin Cooperative Services, located near Stanton, ND, that use to provide lignite to fuel Basin Electric’s Leland Olds Station. Mining operations ceased at Glenharold in June 1993.

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A fire fighting system which floods an area with non combustible halogenated hydrocarbons, preventing air from reaching and sustaining a fire. Some control rooms are provided with a Halon system. Should the system engage, all personnel must evacuate as air will be displaced. Self-contained breathing apparatus are necessary for re-entry.

Heat exchanger

A piece of equipment having a tubular piping arrangement which effects the transfer of heat from a hot to a relatively cool material by conduction through the tube walls; having a countercurrent or concurrent flow of hot and cold materials.


A compound containing only hydrogen and carbon. They form the principal constituents of petroleum. The simplest hydrocarbons are gases at ordinary temperatures; but, with increasing molecular weight, they change to the liquid form and finally the solid state. Their boiling and melting points are, in general, proportional to their molecular weight.


A gaseous element, colorless, odorless, tasteless, flammable, and lighter than any other isolated element. Its symbol is H, and in conjunction with carbon it forms many long series of compounds which are the most important constituents of petroleum.

Hydrostatic testing

A means by which the strength of a section of pipe can be checked by filling it with water under pressure and then shutting in that section and monitoring the pressure.

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Ignition point

The combination of temperature, presence of oxygen, and fuel source that will cause self sustained burning.

Inert gas

A gas which has no reactive properties, commonly nitrogen. Sometimes used as a blanketing gas.


The unwanted entry of a liquid or gas into an enclosed system, e.g., the leakage of groundwater into sewage piping, or air into the negative pressure zone of a fired heater.


A particular type of jet pump which uses a condensable gas to entrain a liquid and discharge against a pressure higher than either motive or suction pressure. Principally a boiler injector.

Integrated gasification combined cycle (IGCC)

Coal, oxygen and steam are combined at high pressures to produce syngas. This resulting gas is burned in a combustion turbine to produce power. Exhaust gases are then run through a heat recovery system generator, which generates steam to run a steam turbine-generator. It's generally a more efficient process that enables easier pollutant and carbon dioxide capture. Modern designs have only been demonstrated with Eastern coals.


The boundary between two systems, oil and water, water and air, etc.


Di-isopropyl ether. Extraction solvent used to absorb phenol in the phenosolvan process.

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Knock-out drum

A drum of vessel, either open or constructed with baffles, through which a mixture of gas and liquid passes to disengage gas from the liquid. This occurs because of a reduction in velocity upon entering the knock-out drum, and is also due to the difference in density between the gas and liquid.


Rare gases used in specialty lighting, such as halogen headlights, lasers, and projector bulbs.

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Laramie River Station (LRS)

Located near Wheatland, WY, LRS is a three-unit, coal-based generating station with a 1,650-megawatt capacity. LRS and its associated facilities are owned by the six consumer-owned participants in the Missouri Basin Power Project. Basin Electric has a 42.27 percent interest in the project and is the operating agent.

Leland Olds Station (LOS)

A two-unit, coal-based generating station with a 656-megawatt capacity. LOS, located near Stanton, ND, is Basin Electric’s oldest generating plant.


The process by which soluble components of a solid mixture are removed by a solvent flowing through the solids. The liquid stream leaving containing soluble components is the leachate.


The presence in the effluent of a species of ions in the feed to an ion exchanger that should have een adsorbed. Due to either exceeding the capacity of the ion exchange resin, or the ion exchange resin suffering a loss of capacity.


A brownish black coal intermediate between peat and bituminous coal.

Liquefied natural gas (LNG)

Methane that has been cooled and liquefied for easier long-distance transport.

Liquefied Petroleum Gas (LPG)

Liquid propane and/or butane sold for home heating.

Liquid nitrogen

Used in food processing refrigeration.


A process stream having a high concentration of organic and inorganic soluble compounds.


Process or electrical system where the start point and end point come back together and interreact to a function.

Lurgi process

A coal gasification process which produces gas in a reactor through the controlled reaction of coal and oxygen in the presence of excess steam at elevated temperatures and pressures.

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A piping arrangement which allows one stream of liquid or gas to be divided into two or more streams.


A barrier, usually thin, that permits the passage only of particles up to a certain size or of special nature.


Sulfur compounds, analogous to alcohols, in which sulfur has replaced oxygen. They are colorless, flammable liquids with a strong, repulsive odor. There is a long series of organic mercaptans, many of which occur naturally in crude oil. Some types of mercaptans are added to natural gas to indicate gas leaks by odor detection.


An instrument, apparatus, or machine for measuring flow of fluids, gases, electric currents, etc.


The initial member (CH4) of the paraffin CnH (2n + 2) series of hydrocarbons. It is an odorless, flammable gas.


A flammable colorless liquid infinitely soluble in water (CH3OH). The simplest possible alcohol.


A process of converting carbon monoxide and carbon dioxide present in synthetic gas to methane, using hydrogen, steam, heat and appropriate catalysts. This process increases the Btu content of SNG.


Organisms (microbes) observable only through a microscope; larger, visible types are called macroorganisms.

Missouri Basin Power Project (MBPP)

A power supply project that owns the Laramie River Station. Its participants include Wyoming Municipal Power Agency, Lusk, WY; Tri-State Generation and Transmission Association, Denver, CO; Missouri River Energy Services of Sioux Falls, SD; Heartland Consumers Power District, Madison, SD; Lincoln Electric System, Lincoln, NE; and Basin Electric. Basin Electric has a 42.27 percent interest in the project and is the operating agent.

Mixed gas

The combined converted shifted gas and raw gas received by the Rectisol Unit from the gas cooling unit.


The smallest part of a substance that can exist separately and still retain its composition and characteristic properties. The smallest combination of atoms that will form a distinct chemical substance.

Molecular seal

A gaseous seal to prevent air from entering a flare. Generally it is an inverted bucket with a baffled seal arrangement. Natural gas, which is lighter than air forms a pocket under the bucket, preventing air ingress.

Molecular sieve

A synthetic zeolite mineral having pores of uniform size, it is capable of separating molecules on the basis of their size, structure, or both, by adsorption or sieving. Often used to remove water from gas.

Molecular weight

The sum of the weights of the atoms in a molecule.

Montana Limestone Company (MLC)

A subsidiary of Dakota Coal company, acquired in 2001. Located near Warren, MT, the MLC quarry supplies raw limestone to Wyoming Lime Producer’s kiln near Frannie, WY. It also markets limestone for commercial applications.

Multiple effect evaporators

 A series of evaporator vessels arranged so that the vapor generated in one body is the heat source for the next. Each evaporator is at a lower pressure than the preceding.

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Can be used for motor gasoline blending and can supply other petrochemical feedstocks. It’s a byproduct of the Synfuels Plant’s coal gasification process.


Refined or partly refined light distillates with an approximate boiling point range of 27 degrees to 221 degrees Centigrade. Blended further or mixed with other materials, they make high-grade motor gasoline or jet fuel. Also, used as solvents, petrochemical feedstocks, or as raw materials for the production of town gas.

Natural gas

A gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, propane, butane, and pentane used for electric generation, heating, cooking, and public transportation. Natural gas, most commonly used as a fuel for peaking plants rather than baseload generation, accounts for about 7 percent of the power produced by generation and transmission cooperatives and 11 percent of all electric cooperative power requirements nationwide.


To make chemically neutral, specifically the addition of an acid to a base or vice versa such that the resultant solution is neither acidic nor basic.


Readily vaporizes in air to a colorless, odorless gas that is used as a cryogenic refrigerant. Liquid nitrogen removes heat from its surroundings as it vaporizes. It is a Synfuels Plant byproduct.

Nitrogen oxides

Compounds of nitrogen and oxygen formed when fossil fuels burn and a leading contributor to smog.

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The percentage of light not transmitted through a plume. Commonly measured by the Ringlemann scale.


The passage of water through a permeable membrane separating two solutions of different concentrations; the water passes into the more concentrated solution.


The loss of electrons by a chemical or chemical compound. The oxidizer may be oxygen but does not have to be.

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A Synfuels Plant byproduct that is a flammable, colorless, oily liquid used for the manufacture of adhesives such as plywood glue. Phenol resins are also used for laminates and molding compounds.

Phenol recovery

Phenolic compounds are removed from the gas liquor and upgraded to pure phenol and cresylic acid.


Any of various organic compounds which are hydroxyl derivatives of aromatic hydrocarbons.


Process using solvent (IPE) to extract phenol from gas liquor.


The process of converting carbon dioxide and water to carbohydrates, activated by sunlight in the presence of chlorophyll, liberating oxygen.


A device used to clean the internal surface of a pipeline. They are inserted into the pipeline by means of a device called a pig-trap and pushed through the line by pressure. The forward movement of the pig, together with its rotation, cleans the rust, liquids and other undesired substances from the pipeline; also called a go-devil.

Pilot plant

A small scale plant, slightly larger than a laboratory model, but smaller than a commercial size plant, used in experimental work.


A contaminant at a concentration high enough to endanger the aquatic environment or the public health.

Potable water

Drinking water.


Any form or apparatus in which heat is applied to a material prior to its introduction into a main heating apparatus. The application of heat is usually affected by means of hot bodies which have to be cooled, and whose heat would otherwise be wasted.

Pressure vessel

An enclosed vessel which is maintained at a pressure greater than atmospheric.

Process variable

The process parameter that is being controlled, such as temperature, flow, pressure, etc.


The third member of the octane series, C3H8. It is a colorless, flammable gas found in crude petroleum and natural gas.


The displacement of one material with another in process equipment; frequently displacement of hydrocarbon vapor with steam or inert gas.

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The transfer of heat through space in all directions without affecting the intervening space.

Rate of flow

The volume or units of material passing a given point in a system per unit of time.

Raw gas

Crude gas that has been cooled in the gas cooling unit.


A vessel in which hydrocarbons are reacted with chemicals or other hydrocarbons to obtain the desired end products.


An auxiliary of a distillation tower designed to supply additional heat to the lower portion.

Recirculating cooling water

Closed loop cooling water system (cooled by air exchangers rather than cooling tower) for heat removal from blowers, pumps, compressors, etc., inhibitors added.


Term applied to the practice of returning one of the end products to the reaction section for additional processing.

Recovered energy

Technology used to recover the heat energy that is released as an unused byproduct from an existing industrial process. An example is the recovered energy projects recently commissioned for Basin Electric. These projects involve the capture of the hot exhaust gases released by combustion turbines as they drive compressors to propel natural gas down the pipeline. Also known as waste heat recovery, these projects capture and use heat that would otherwise be lost, if not recovered through this process.


Processing section which removes carbon dioxide, naphtha, sulfur compounds and hydrocarbons from the mixed gas sent from gas cooling by contacting with cold methanol.


Any material not easily affected by heat, such as firebrick; also, a refractory hydrocarbon which is difficult to crack further.


A restoration of activity to enable reuse of the substance. In a catalytic process, the reactivation of the catalyst, sometimes done by burning off the coke deposits under carefully controlled conditions of temperature and oxygen content of the regeneration gas stream.


A valve which directly controls the flow of liquid or gas through a line; usually actuated by an instrument to control pressure, temperature or flow conditions.


A heat exchanger located in a furnace to increase the temperature of steam extracted from a turbine for reinjection.


The solid or liquid matter remaining after the extraction of certain constituents of a mixture or solution. That portion of the crude material which remains after the separation of any of its parts.

Reverse osmosis

A process that reverses (by the application of pressure) the flow of water in the natural process of osmosis so that it passes from the more concentrated to the more dilute solution.

Reaction rate

The speed at which a reaction takes place.


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Safety valve

A special valve on the top of a vessel or in the vapor line, set to open a certain pressure. It prevents damage to equipment and injury.


Equipment that removes sulfur dioxide from combustion gases using a chemical reaction. Whether a scrubber is "wet" or "dry" depends on the amount of water used in the process and the state of the new compound formed from the chemical reaction.


Purification of a gas or liquid by washing it in a tower or agitator.


A vessel used to separate vapors from liquid; e.g. steam from condensate, or settling basin used to separate oil from water.

Shift conversion

The reaction of carbon monoxide and steam to form hydrogen and carbon dioxide.

Shift gas

The process gas from the shift reactor.


A solid waste containing a high percentage of water.


A water containing a high concentration of suspended solids, usually over 5,000 mg/l.


A substance, usually a liquid, capable of absorbing another liquid, gas or solid, to form a homogeneous mixture.

Souris Valley Pipeline Limited

A wholly owned, for-profit Canadian subsidiary of Dakota Gasification Company formed to own and maintain 35 miles of carbon dioxide pipeline in Canada.

Spirit Mound Station (SMS)

Basin Electric’s two-unit, oil-fired generating station for peak- and emergency-demand periods. Located near Vermillion, SD, Spirit Mound has a 104-megawatt capacity.

Standard cubic feet (SCF)

Measurement of the volume of gas. Standard conditions in a petroleum and natural gas usage refer to a pressure base of 14.696 psi and a temperature base of 60 degrees Fahrenheit.

Static pressure

Acting by mere weight without motion; bodies or forces at rest or in equilibrium.

Steam generation

Steam used in gasification and for other requirements is produced on site by three multi-fuel boilers. They are fired with tar oil, naphtha/phenol, off-gas from sulfur recovery, lock gas, raw gas and natural gas. The process steam generation system is designed to produce steam, superheat steam generated in process areas, and incinerate and recover heat from waste gas streams.


The removal of the light fraction from a liquid in a drum or tower with the aid of steam admitted to the bottom of the drum or tower.

Superheated steam

Steam which is heated above the boiling temperature of water at that pressure.


A vessel in which a vapor is heated to a temperature higher than the condensing temperature at the same pressure.


The combined action of two or more chemicals which produces an effect greater than the additive effects of each acting individually.


Any gaseous mixture generated by the gasification of a carbon-containing fuel, such as coal, or municipal waste. Also includes the steam reforming of natural gas or oil to produce hydrogen.

Synthesis gas

The materials from which product compounds are made synthetically.

Synthetic fuel

Combustible liquid obtained from coal, natural gas, biomass, or other solids such as oil shale, tar sand, and waste plastics.

Synthetic natural gas

Fuel in the form of liquid or gas (synthetic natural gas) manufactured from coal using a conversion process.

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The hotness or coldness or matter; in petroleum refining plant operations in the United States, almost all temperatures are reported in degrees Fahrenheit.

Tie in

To make a connection to an existing pipeline or piping.


A device which measures the process variable and converts that measurement to a signal usable by the control system.

Trip shutdown

An example is equipment that malfunctions and as a result shuts down other equipment causing a trip in the system.


Work period necessary to clean and make minor repairs on equipment after a normal run. It is usually the elapsed time between shutting the unit down and placing the unit on stream again.

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Ultrasonic testing

A nondestructive test applied to sound conductive materials having elastic properties for the purpose of locating nonhomogenities or structural discontinuities within a material by means of ultrasonic impulses (inaudible high frequency sound waves). Also useful in measuring thicknesses of metal where access is available to only one side.

U.S. Department of Energy (DOE)

The federal cabinet-level department responsible for implementing national energy policy.

U.S. Environmental Protection Agency (EPA)

A federal bureau with cabinet-level status that oversees the nation’s environmental science, research, education, and assessment efforts. One of its primary duties involves developing and enforcing rules and regulations for environmental protection.

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The condition which exists in a vessel when the pressure is less than the outside atmospheric pressure.


Gaseous substance which can be at least partly condensed by cooling or compression.


Converts liquid to gas.

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Water scrubber

An apparatus in which gases are bubbled through water to wash out the last traces of any gas soluble in water.

Water treatment

Feedwater consists of primary treated water from Antelope Valley Station (AVS). Reverse osmosis is used to produce high-quality boiler feedwater for the plan’s steam generators. This unit also contains facilities for maintaining water quality.

William J. Neal Station(WJN)

A former coal-based generating station with a 47-megawatt capacity that Basin Electric owned. The William J. Neal Station was located near Velva, ND. It has been dismantled.

Wyoming Distributed Generation Project (WDG)

Located in Wyoming's Powder River Basin, the WDG Project, consisting of nine natural gas fired combustion turbine generators (CTGs), supplies energy and voltage support to Basin Electric’s largest member, Powder River Energy Corporation (PRECorp). The CTGs are remotely operated on an as-needed basis from the Antelope Valley Station near Beulah, ND.

Wyoming Lime Producers (WLP)

A division of Dakota Coal Company that owns a lime kiln near Frannie, WY, that began operating in 1993.

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A Synfuels plant byproduct used in high intensity lamps such as projector bulbs and in laser applications.

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