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Naphtha (pronounced /ˈnæfθə/ or /ˈnæpθə/) normally refers to a number of different flammable liquid mixtures of hydrocarbons, i.e. a distillation product from petroleum or coal tar boiling in a certain range and containing certain hydrocarbons, a broad term encompassing any volatile, flammable liquid hydrocarbon mixture.

Naphtha is used primarily as feedstock for producing a high octane gasoline component (via the catalytic reforming process). It is also used in the petrochemical industry for producing olefins in steam crackers and in the chemical industry for solvent (cleaning) applications.

Etymology

The word naphtha came from Latin and Greek. It is an Ancient Greek word that was used to refer to any sort of petroleum or pitch. It appears in Arabic as "nafţ" (نَفْط) ("petroleum"), and in Hebrew as "neft" (נֵפְט). Arabs and Persians have used and distilled petroleum for tar and fuel from ancient times, as attested in local Greek and Roman histories of the region.

Naphtha is the root of the word naphthalene. The second syllable of "naphtha" can also be recognised in phthalate.

It also enters the word napalm from "naphthenic acid and palmitic acid", as the first napalm was made from a mixture of naphthenic acid with aluminium and magnesium salts of palmitic acid.

In older usage, "naphtha" simply meant crude oil, but this usage is now obsolete.

The ukrainian word нафта (lit. nafta) and the russian word нефть (lit. neft') mean exactly "crude oil". Also, in Italy nafta is colloquially used to indicate diesel fuel.

There is a conjecture that the word "naphtha" came (via Greek, where it meant any sort of petroleum) from the Vedic god name Apam Napat; the name Apam Napat is also found in Avestic.[1]

Health and safety considerations

Forms of naphtha may be carcinogenic, and frequently products sold as naphtha contain some impurities which may also have deleterious properties of their own. [2][3] Like many hydrocarbon products, they are products of a refining process in which a complex soup of chemicals is broken into another range of chemicals, which are then graded and isolated mainly by their specific gravity and volatility. There is, therefore, a range of distinct chemicals included in each product. This makes rigorous comparisons and identification of specific carcinogens difficult, especially in our modern environment where exposure to a great number of such products occurs on a daily basis, and is further complicated by exposure to a significant range of other known and potential carcinogens (e.g., see[4]).

Below are linked some Material Safety Data Sheet (MSDS) specifications for different "naphtha" products containing varying degrees of naphtha, as well as various other chemicals. As well as giving health guidelines, these are some of the few ways to determine what a given product contains.

  • JT Baker VM&P Naphtha MSDS.
  • Diggers Shellite MSDS
  • Shell Ronsonol MSDS source1 source2formula developed for Ronson
  • Links to more MSDS for various camping-stove fuels including several that include naphtha

Benzene in particular is a known high-risk carcinogen, so benzene content is typically specified in the MSDS when it is present in the mixture due to the specifics of the feedstock and distilling process used. Specific detailing of other hydrocarbon species is less common.

Properties

Physical

Molecular weight range is 100-215 g/mol; specific gravity range is 0.75-0.85 g/cm3; boiling point range is 160-220 °C (320-430 °F); vapor pressure is < 5 torr (5 mm Hg). Naphthas are insoluble in water; colorless (kerosene odor) or red-brown (aromatic odor) liquid; incompatible with strong oxidizers.

Production in refineries

Naphtha is obtained in petroleum refineries as one of the intermediate products from the distillation of crude oil. It is a liquid intermediate between the light gases in the crude oil and the heavier liquid kerosene. Naphthas are volatile, flammable and have a specific gravity of about 0.7. The generic name 'naphtha' describes a range of different refinery intermediate products used in different applications. To complicate the matter further, similar naphtha types are often referred to by different names.

The different naphthas are distinguished by:

  • Density (g/ml or specific gravity)
  • PONA, PIONA or PIANO analysis, which measures (usually in volume percent but can also be in weight percent):

Different types

Paraffinic

Generally speaking, less dense ("lighter") naphthas will have a higher paraffin content. These are therefore also referred to as paraffinic naphtha. The main application for these naphthas is as a feedstock in the petrochemical production of olefins. This is also the reason they are sometimes referred to as "light distillate feedstock" or LDF (These naphtha types can also be called "straight run gasoline"/SRG or "light virgin naphtha"/LVN).

When used as feedstock in petrochemical steam crackers, naphtha is heated in the presence of water vapour and the absence of oxygen or air until the hydrocarbon molecules fall apart. The primary products of the cracking process are olefins (ethylene / ethene, propylene / propene and butadiene). When naphtha is used as a feedstock in catalytic reforming the primary products are aromatics including benzene, xylene, and toluene. The olefins are used as feedstocks for derivative units that produce plastics (polyethylene and polypropylene for example), synthetic fiber precursors (acrylonitrile), industrial chemicals (glycols for instance) while the aromatics are used for octane boosting in fuel blending as well as polyethylene terphthalate PET feedstock and paint and coating solvents.

Heavy

White gas, exemplified by Coleman Camp Fuel, is a common naphtha fuel used in many lanterns and torches

The "heavier" or rather denser types are usually richer in naphthenes and aromatics and therefore also referred to as N&A's. These can also be used in the petrochemical industry but more often are used as a feedstock for refinery catalytic reformers where they convert the lower octane naphtha to a higher octane product called reformate. Alternative names for these types are Straight Run Benzene (SRB) or Heavy Virgin Naphtha (HVN).

Other applications

Naphthas are also used in other applications such as:

  • An unprocessed component (in contrast to reforming above) in the production of petrol/motor gasoline;
  • Industrial solvents and cleaning fluids;
  • A commonly available general purpose solvent designated as "VM&P" naphtha, which stands for "varnish makers' and painters'";
  • An oil painting medium;
  • The sole ingredient in the home cleaning fluid Energine, which has been discontinued;
  • An ingredient in shoe polish;
  • An ingredient in some lighter fluids for wick type lighters such as Zippo lighters;
  • An adulterant to petrol;
  • A fuel for portable stoves and lanterns, sold in North America as white gas, camp fuel or Coleman fuel;
  • Historically, as a probable ingredient in Greek fire (together with grease, oil, sulfur, and naturally occurring saltpeter from the desert);
  • A fuel for fire spinning, fire juggling, or other fire performance equipment which creates a brighter and cleaner yet shorter burn;
  • To lightly wear the finish (polish) off guitars when preparing "relic" instruments;
  • To remove from the aperture blades of camera lenses any oil which, if present, could slow the movement of the blades, leading to overexposure;
  • As a coating for elemental lithium metal, to prevent oxidation (mineral oil is also used for this purpose);
  • As a fuel in gas turbine unit;
  • As the working fluid (and sometimes, fuel) in the naphtha (external combustion) engine.

In medieval times, pots containing naphtha were used in battle as a form of primitive grenade. In Ancient China, monks used forms of Naphtha to prepare in religious ceremonies such as Chimbohduh.

Naphtha is used in the furniture industry on "works in progress" to see temporarily (until the naphtha evaporates) how the patina will look when the piece is oiled and/or aged. It is useful in matching adjacent boards for a join, primarily with tabletops, panels and shelves.

Health hazards

"Light naphtha, a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from five to nine carbon atoms per molecule. Heavy naphtha, a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from seven to nine carbons per molecule."[5] "Almost all volatile, lipid-soluble organic chemicals cause general, nonspecific depression of the central nervous system or general anesthesia."[6] The OSHA PEL TWA = 100 parts-per-million (ppm); Health Hazards/Target Organs = eyes, skin, RS, CNS, liver, kidney. Symptoms of acute exposure are dizziness and narcosis with loss of consciousness. The World Health Organization categorizes health effects into three groups: reversible symptoms (Type 1), mild chronic encephalopathy (Type 2) and severe chronic toxic encephalopathy (Type 3).

Topical exposure to naphtha can cause a burning sensation on the skin within a period of minutes to an hour, followed by contact dermatitis—a rash—that can last for days to weeks.

Examples in daily life

Shellite (Australia), also known as white gas (North America), white spirit (outside the UK) or Coleman fuel, is a white liquid with a hydrocarbon odour. Shellite has a freeze point lower than −30 °C (−22 °F), and a boiling point of 47 °C (117 °F). The composition of shellite is 95% paraffins and naphthenes, less than 5% aromatic hydrocarbons and less than 0.5% benzene. It is highly flammable and due to its low flashpoint is used in many low pressure camping stoves. Shellite is also a fast drying solvent used for cleaning metal, hard plastic and painted surfaces. Ronsonol is a brand name used in North America, for a product marketed principally as a refill fluid for cigarette lighters and having a flashpoint of about 6 °C (43 °F).

See also

References

  1. ^ Studies in ancient technology by R. J. Forbes (page 12)
  2. ^ http://nafaa.pbwiki.com/Naphtha
  3. ^ http://monographs.iarc.fr/ENG/Monographs/vol47/volume47.pdf
  4. ^ http://www.defence.gov.au/dpe/dhs/research/shoamp/Mortality_Final_report_Sept_2003.pdf
  5. ^ "Chemistry of Hazardous Materials, Third Edition", Meyer, E., Prentice Hall, 1998, page 458.
  6. ^ "Occupational and Environmental Medicine, Third Edition", LaDou, J. , MS., MD. Lange Medical Books, McGraw Hill, 2004, page 508.

External links

Additional sources

  • McDermott, Henry J. (2004). Air Monitoring for Toxic Exposures (Second Edition) John Wiley & Sons, Inc.

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

NAPHTHA, a word originally applied to the more fluid kinds of petroleum, issuing from the ground in the Baku district of Russia and in Persia. It is the vacOa of Dioscorides, and the naphtha, or bitumen liquidum candidum of Pliny. By the alchemists the word was used principally to distinguish various highly volatile, mobile and inflammable liquids, such as the ethers, sulphuric ether and acetic ether having been known respectively as naphtha sulphurici and naphtha aceti. The term is now seldom used, either in commerce or in science, without a distinctive prefix, and we thus have the following: I. Coal-tar Naphtha. - A volatile commercial product obtained by the distillation of coal-tar (see Coal-Tar).

2. Shale Naphtha. - Obtained by distillation from the oil produced by the destructive distillation of bituminous shale (see Paraffin).

3. Petroleum Naphtha

A name sometimes given (e.g. in the United States) to a portion of the more volatile hydrocarbons distilled from petroleum (see Petroleum).

4. Wood Naphtha. - Methyl alcohol.

5. Bone Naphtha

Known also as bone oil orDippel's oil. A volatile product of offensive odour obtained in the carbonization of bones for the manufacture of animal charcoal.

6. Caoutchouc Naphtha

A volatile product obtained by the destructive distillation of rubber. (B. R.)


<< Naphtali

Naphthalene >>


Simple English

Naphtha (not to be confused with Naphthalene) is the name for a number of intermediary products that occur when refining crude oil. They are liquid hydrocarbons. They are used to produce high octane gasoline products. The petrochemical industry also uses them to make olefins and solvents.

Typical naphtas are used for

  • Solvents in cleaning fluid
  • As an ingredient of Shoe polish
  • As an ingredient for some of the fuels used in lighters
  • Possibly one of the things in Greek fire.








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