Industrial gases are thegaseous materials that aremanufactured for use inindustry. The principal gases provided arenitrogen,oxygen,carbon dioxide,argon,hydrogen,helium andacetylene, although many other gases and mixtures are also available in gas cylinders. The industry producing these gases is also known asindustrial gas, which is seen as also encompassing the supply of equipment and technology to produce and use the gases.[1] Their production is a part of the widerchemical Industry (where industrial gases are often seen as "specialty chemicals").
Industrial gases are used in a wide range of industries, which includeoil and gas,petrochemicals,chemicals,power,mining,steelmaking,metals,environmental protection,medicine,pharmaceuticals,biotechnology,food,water,fertilizers,nuclear power,electronics andaerospace. Industrial gas is sold to other industrial enterprises; typically comprising large orders tocorporate industrial clients, covering a size range from building a process facility or pipeline down to cylinder gas supply.
Sometrade scale business is done, typically through tiedlocal agents who are suppliedwholesale. This business covers thesale orhire of gas cylinders and associated equipment totradesmen and occasionally the general public. This includes products such asballoon helium, dispensing gases forbeer kegs, welding gases and welding equipment, LPG andmedical oxygen.
Retail sales of small scale gas supply are not confined to just the industrial gas companies or their agents. A wide variety of hand-carried small gas containers, which may be called cylinders, bottles, cartridges, capsules or canisters are available to supply LPG, butane, propane, carbon dioxide or nitrous oxide. Examples arewhipped-cream chargers,powerlets,campingaz andsodastream.
The first gas from the natural environment used by humans was almost certainlyair when it was discovered that blowing on or fanning a fire made it burn brighter. Humans also used thewarm gases from a fire tosmoke foods andsteam from boiling water to cook foods.
Carbon dioxide has been known from ancient times as the byproduct offermentation, particularly forbeverages, which was first documented dating from 7000 to 6600 B.C. inJiahu,China.[2]Natural gas was used by the Chinese in about 500 B.C. when they discovered the potential to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to boil sea water.[3]Sulfur dioxide was used by the Romans in winemaking as it had been discovered that burningcandles made of sulfur[4] inside empty wine vessels would keep them fresh and prevent them gaining a vinegar smell.[5]
Early understanding consisted ofempirical evidence and theprotoscience ofalchemy; however with the advent ofscientific method[6] and thescience ofchemistry, these gases became positively identified and understood.
Thehistory of chemistry tells us that a number of gases were identified and either discovered or first made in relatively pure form during theIndustrial Revolution of the 18th and 19th centuries by notablechemists in theirlaboratories. The timeline of attributed discovery for various gases are carbon dioxide (1754),[7] hydrogen (1766),[8][9] nitrogen (1772),[8] nitrous oxide (1772),[10] oxygen (1773),[8][11][12] ammonia (1774),[13] chlorine (1774),[8] methane (1776),[14] hydrogen sulfide (1777),[15] carbon monoxide (1800),[16] hydrogen chloride (1810),[17] acetylene (1836),[18] helium (1868)[8][19] fluorine (1886),[8] argon (1894),[8] krypton, neon and xenon (1898)[8] and radon (1899).[8]
Carbon dioxide, hydrogen, nitrous oxide, oxygen, ammonia, chlorine, sulfur dioxide andmanufactured fuel gas were already being used during the 19th century, and mainly had uses infood,refrigeration,medicine, and forfuel andgas lighting.[20] For example,carbonated water was being made from 1772 and commercially from 1783, chlorine was first used to bleach textiles in 1785[21] andnitrous oxide was first used for dentistry anaesthesia in 1844.[10] At this time gases were often generated for immediate use bychemical reactions. A notable example of a generator isKipps apparatus which was invented in 1844[22] and could be used to generate gases such as hydrogen,hydrogen sulfide, chlorine, acetylene and carbon dioxide by simplegas evolution reactions. Acetylene was manufactured commercially from 1893 and acetylene generators were used from about 1898 to produce gas forgas cooking andgas lighting, however electricity took over as more practical for lighting and once LPG was produced commercially from 1912, the use of acetylene for cooking declined.[20]
Once gases had been discovered and produced in modest quantities, the process ofindustrialisation spurred oninnovation andinvention oftechnology to produce larger quantities of these gases. Notable developments in the industrial production of gases include theelectrolysis of water to produce hydrogen (in 1869) and oxygen (from 1888), theBrin process for oxygen production which was invented in the 1884, thechloralkali process to produce chlorine in 1892 and theHaber Process to produce ammonia in 1908.[23]
The development of uses in refrigeration also enabled advances inair conditioning and the liquefaction of gases. Carbon dioxide was first liquefied in 1823. The firstVapor-compression refrigeration cycle usingether was invented byJacob Perkins in 1834 and a similar cycle usingammonia was invented in 1873 and another with sulfur dioxide in 1876.[20]Liquid oxygen andLiquid nitrogen were both first made in 1883;Liquid hydrogen was first made in 1898 andliquid helium in 1908.LPG was first made in 1910. A patent forLNG was filed in 1914 with the first commercial production in 1917.[24]
Although no one event marks the beginning of the industrial gas industry, many would take it to be the 1880s with the construction of the first high pressuregas cylinders.[20] Initially cylinders were mostly used for carbon dioxide incarbonation or dispensing of beverages. In 1895 refrigeration compression cycles were further developed to enablethe liquefaction of air,[25] most notably byCarl von Linde[26] allowing larger quantities of oxygen production and in 1896 the discovery that large quantities of acetylene could be dissolved inacetone and rendered nonexplosive allowed the safe bottling of acetylene.[27]
A particularly important use was the development ofwelding and metal cutting done with oxygen and acetylene from the early 1900s.As production processes for other gases were developed many more gases came to be sold in cylinders without the need for agas generator.
Air separation plantsrefine air in aseparation process and so allow the bulk production ofnitrogen andargon in addition to oxygen - these three are often also produced ascryogenicliquid. To achieve the required lowdistillation temperatures, an Air Separation Unit (ASU) uses arefrigeration cycle that operates by means of theJoule–Thomson effect. In addition to the main air gases, air separation is also the only practical source for production of therarenoble gasesneon,krypton andxenon.
Cryogenic technologies also allow theliquefaction ofnatural gas,hydrogen andhelium. Innatural-gas processing, cryogenic technologies are used to remove nitrogen from natural gas in aNitrogen Rejection Unit; a process that can also be used to producehelium from natural gas wherenatural gas fields contain sufficient helium to make this economic. The larger industrial gas companies have often invested in extensivepatent libraries in all fields of their business, but particularly in cryogenics.
The other principal productiontechnology in the industry is Reforming.Steam reforming is achemical process used to convert natural gas andsteam into asyngas containinghydrogen andcarbon monoxide withcarbon dioxide as abyproduct.Partial oxidation andautothermal reforming are similar processes but these also require oxygen from an ASU. Synthesis gas is often a precursor to thechemical synthesis of ammonia ormethanol. The carbon dioxide produced is anacid gas and is most commonly removed byamine treating. This separated carbon dioxide can potentially besequestrated to acarbon capturereservoir or used forEnhanced oil recovery.
Air Separation and hydrogen reforming technologies are the cornerstone of the industrial gases industry and also form part of the technologies required for many fuelgasification ( includingIGCC),cogeneration andFischer-Tropschgas to liquids schemes. Hydrogen has manyproduction methods and may be almost acarbon neutralalternative fuel if produced by water electrolysis (assuming the electricity is produced in nuclear or other low carbon footprint power plant instead of reforming natural gas which is by far dominant method). One example of displacing the use of hydrocarbons is Orkney;[28] seehydrogen economy for more information on hydrogen's uses.Liquid hydrogen is used by NASA in theSpace Shuttle as arocket fuel.
Simplergas separation technologies, such asmembranes ormolecular sieves used inpressure swing adsorption orvacuum swing adsorption are also used to produce low purity air gases innitrogen generators andoxygen plants. Other examples producing smaller amounts of gas arechemical oxygen generators oroxygen concentrators.
In addition to the major gases produced by air separation and syngas reforming, the industry provides many other gases. Some gases are simply byproducts from other industries and others are sometimes bought from other larger chemical producers, refined and repackaged; although a few have their own production processes. Examples are hydrogen chloride produced by burning hydrogen in chlorine, nitrous oxide produced bythermal decomposition ofammonium nitrate when gently heated,electrolysis for the production of fluorine, chlorine and hydrogen, and electricalcorona discharge to produceozone from air or oxygen.
Related services and technology can be supplied such asvacuum, which is often provided inhospital gas systems;purifiedcompressed air; orrefrigeration. Another unusual system is theinert gas generator. Some industrial gas companies may also supply relatedchemicals, particularly liquids such asbromine,hydrogen fluoride andethylene oxide.
Most materials that are gaseous at ambient temperature and pressure are supplied as compressed gas. Agas compressor is used to compress the gas into storagepressure vessels (such asgas canisters, gas cylinders ortube trailers) throughpiping systems. Gas cylinders are by far the most common gas storage[29] and large numbers are produced at a"cylinder fill" facility.
However, not all industrial gases are supplied in thegaseous phase. A few gases arevapors that can be liquefied atambient temperature underpressure alone, so they can also be supplied as a liquid in an appropriate container. Thisphase change also makes these gases useful as ambientrefrigerants and the most significant industrial gases with this property areammonia (R717),propane (R290),butane (R600), andsulfur dioxide (R764). Chlorine also has this property but is too toxic, corrosive and reactive to ever have been used as a refrigerant. Some other gases exhibit this phase change if the ambient temperature is low enough; this includesethylene (R1150),carbon dioxide (R744),ethane (R170),nitrous oxide (R744A), andsulfur hexafluoride; however, these can only be liquefied under pressure if kept below theircritical temperatures which are 9 °C for C2H4 ; 31 °C for CO2 ; 32 °C for C2H6 ; 36 °C for N2O ; 45 °C for SF6.[30] All of these substances are also provided as a gas (not a vapor) at the 200bar pressure in a gas cylinder because that pressure is above theircritical pressure.[30]
Permanent gases (those with a critical temperature below ambient) can only be supplied as liquid if they are also cooled. All gases can potentially be used as a refrigerant around the temperatures at which they are liquid; for example nitrogen (R728) and methane (R50) are used as refrigerant at cryogenic temperatures.[25]
Exceptionallycarbon dioxide can be produced as a coldsolid known asdry ice, whichsublimes as it warms in ambient conditions, the properties of carbon dioxide are such that it cannot be liquid at a pressure below itstriple point of 5.1 bar.[30]
Acetylene is also supplied differently. Since it is so unstable and explosive, this is supplied as a gas dissolved in acetone within apacking mass in a cylinder. Acetylene is also the only other common industrial gas that sublimes at atmospheric pressure.[30]
The major industrial gases can be produced in bulk and delivered to customers bypipeline, but can also be packaged and transported.
Most gases are sold ingas cylinders and some sold as liquid in appropriate containers (e.g.Dewars) or asbulk liquid delivered by truck. The industry originally supplied gases in cylinders to avoid the need for local gas generation; but for large customers such assteelworks oroil refineries, a large gas production plant may be built nearby (typically called an "on-site" facility) to avoid using large numbers of cylindersmanifolded together. Alternatively, an industrial gas company may supply theplant and equipment to produce the gas rather than the gas itself. An industrial gas company may also offer to act asplant operator under anoperations and maintenance contract for a gases facility for a customer, since it usually has the experience of running such facilities for the production or handling of gases for itself.
Some materials are dangerous to use as a gas; for example, fluorine is highly reactive and industrial chemistry requiring fluorine often useshydrogen fluoride (orhydrofluoric acid) instead. Another approach to overcoming gas reactivity is to generate the gas as and when required, which is done, for example, withozone.
The delivery options are therefore local gas generation,pipelines, bulk transport (truck,rail,ship), andpackaged gases in gas cylinders or other containers.[1]
Bulk liquid gases are often transferred to end userstorage tanks. Gas cylinders (and liquid gas containing vessels) are often used by end users for their own small scale distribution systems. Toxic or flammable gas cylinders are often stored by end users ingas cabinets for protection from external fire or from any leak.
Despite attempts at standardization to facilitate user and first responders' safety, no universal coding exists for cylinders with industrial gases, therefore several color coding standards are in usage. In mostdeveloped countries of the world, notably countries of European union and United Kingdom, EN 1089-3 is used, with cylinders ofliquefied petroleum gas being an exception.
In United States of America, no official regulation of color coding for gas cylinders exists and none is enforced.[31]
Industrial gas is a group of materials that are specifically manufactured for use inindustry and are also gaseous at ambient temperature and pressure. They arechemicals which can be anelemental gas or achemical compound that is eitherorganic orinorganic, and tend to be lowmolecular weight molecules. They could also be amixture of individual gases. They have value as a chemical; whether as afeedstock, in process enhancement, as a useful end product, or for a particular use; as opposed to having value as a "simple"fuel.
The term “industrial gases”[32] is sometimes narrowly defined as just the major gases sold, which are: nitrogen, oxygen, carbon dioxide, argon, hydrogen, acetylene and helium.[33] Many names are given to gases outside of this main list by the different industrial gas companies, but generally the gases fall into the categories "specialty gases", “medical gases”, “fuel gases” or “refrigerant gases”. However gases can also be known by their uses or industries that they serve, hence "welding gases" or "breathing gases", etc.; or by their source, as in "air gases"; or by their mode of supply as in "packaged gases". The major gases might also be termed "bulk gases" or "tonnage gases".
In principle any gas or gas mixture sold by the "industrial gases industry" probably has some industrial use and might be termed an "industrial gas". In practice, "industrial gases" are likely to be a pure compound or a mixture of precisechemical composition, packaged or in small quantities, but with highpurity or tailored to a specific use (e.g.oxyacetylene).Lists of the more significant gases are listed in "The Gases" below.
There are cases when a gas is not usually termed an "industrial gas"; principally where the gas isprocessed for later use of itsenergy rather thanmanufactured for use as a chemical substance or preparation.
Theoil and gas industry is seen as distinct. So, whilst it is true that natural gas is a "gas" used in "industry" - often as a fuel, sometimes as a feedstock, and in this generic sense is an "industrial gas"; this term is not generally used by industrial enterprises forhydrocarbons produced by thepetroleum industry directly fromnatural resources or in anoil refinery. Materials such as LPG and LNG are complex mixtures often without precise chemical composition that often also changes whilst stored.
Thepetrochemical industry is also seen as distinct. So petrochemicals (chemicals derived frompetroleum) such asethylene are also generally not described as "industrial gases".
Sometimes the chemical industry is thought of as distinct from industrial gases; so materials such as ammonia and chlorine might be considered "chemicals" (especially if supplied as a liquid) instead of or sometimes as well as "industrial gases".
Small scale gas supply of hand-carried containers is sometimes not considered to be industrial gas as the use is considered personal rather than industrial; and suppliers are not always gas specialists.
These demarcations are based on perceived boundaries of these industries (although in practice there is some overlap), and an exact scientific definition is difficult. To illustrate "overlap" between industries:
Manufacturedfuel gas (such astown gas) would historically have been considered an industrial gas.Syngas is often considered to be a petrochemical; although its production is a core industrial gases technology. Similarly, projects harnessingLandfill gas orbiogas,Waste-to-energy schemes, as well as Hydrogen Production all exhibit overlapping technologies.
Helium is an industrial gas, even though its source is fromnatural gas processing.
Any gas is likely to be considered an industrial gas if it is put in a gas cylinder (except perhaps if it is used as a fuel)
Propane would be considered an industrial gas when used as a refrigerant, but not when used as a refrigerant in LNG production, even though this is an overlapping technology.
The knownchemical elements which are, or can be obtained fromnatural resources (withouttransmutation) and which are gaseous are hydrogen, nitrogen, oxygen, fluorine, chlorine, plus the noble gases; and are collectively referred to by chemists as the "elemental gases".[34] These elements are allprimordial apart from the noble gasradon which is atrace radioisotope which occursnaturally since all isotopes areradiogenic nuclides fromradioactive decay. These elements are allnonmetals.
(Synthetic elements have no relevance to the industrial gas industry; however for scientific completeness, note that it has been suggested, but not scientifically proven, that metallic elements 112 (Copernicium) and 114 (Flerovium) are gases.[35])
The elements which are stabletwo atomhomonuclearmolecules atstandard temperature and pressure (STP), are hydrogen (H2), nitrogen (N2) and oxygen (O2), plus thehalogens fluorine (F2) and chlorine (Cl2). Thenoble gases are allmonatomic.
In the industrial gases industry the term "elemental gases" (or sometimes less accurately "molecular gases") is used to distinguish these gases from molecules that are alsochemical compounds.
Radon is chemically stable, but it isradioactive and does not have astable isotope. Its most stableisotope,222Rn, has ahalf-life of 3.8 days. Its uses are due to its radioactivity rather than its chemistry and it requires specialist handling outside of industrial gas industry norms. It can however be produced as a by-product ofuraniferous ores processing. Radon is a tracenaturally occurring radioactive material (NORM) encountered in the air processed in an ASU.
Chlorine is the only elemental gas that is technically avapor since STP is below itscritical temperature; whilstbromine andmercury are liquid at STP, and so their vapor exists in equilibrium with their liquid at STP.
This list shows the other most common gases sold by industrial gas companies.[1]
There are many gas mixtures possible.
This list shows the most important liquefied gases:[1]
The uses of industrial gases are diverse.
The following is a small list of areas of use:
Media related toIndustrial gases at Wikimedia Commons