Gasoline or petrol is a petroleum-derived liquid mixture consisting mostly of hydrocarbons and enhanced with benzene or iso-octane to increase octane ratings, primarily used as fuel in internal combustion engines. Most Commonwealth countries or former Commonwealth countries, with the exception of Canada, use the term "petrol" (abbreviated from petroleum spirit). The term "gasoline" is commonly used in North America where it is often shortened in colloquial usage to "gas". This should be distinguished in usage from genuinely gaseous fuels used in internal combustion engines such as liquified petroleum gas (which is stored pressurised as a liquid but is allowed to return naturally to a gaseous state before combustion). The term mogas, short for motor gasoline, distinguished automobile fuel from aviation gasoline, or avgas. The word "gasoline" can also be used in British English to refer to a different petroleum derivative historically used in lamps; however, this use is now uncommon. In some countries (most notably Scandinavian countries and Northern Europe, the former Soviet Union, Bulgaria, and Israel), the term benzine is used to refer to what Americans call gasoline.
History
Before internal-combustion engines were invented in the mid 19th century, gasoline was sold in small bottles as a treatment against lice and their eggs. At that time, the word Petrol was a trade name. This treatment method is no longer common, because of the inherent fire hazard and the risk of dermatitis.
In the U.S., gasoline was also sold as a cleaning fluid to remove grease stains from clothing. Before dedicated filling stations were established, early motorists would buy gasoline in cans to fill their tanks.
The name gasoline is similar to that of other petroleum products of the day, most notably petroleum jelly, a highly purified heavy distillate, which was branded Vaseline. The trademark Gasoline, however, was never registered, and thus became generic.
Gasoline was also used in kitchen ranges and for lighting, and is still available in a highly purified form, known as camping fuel or white gas, for use in lanterns and portable stoves.
During the Franco-Prussian War (1870–1871), pétrole was stockpiled in Paris for use against a possible German-Prussian attack on the city. Later in 1871, during the revolutionary Paris Commune, rumours spread around the city of pétroleuses, women using bottles of petrol to commit arson against city buildings.
Early uses
The word "gasolene" was coined in 1865 from the word gas and the chemical suffix -ine/-ene. The modern spelling was first used in 1871. The shortened form "gas" was first recorded in American English in 1905.
In Germany and some other European countries, gasoline is called Benzin. The usage does not derive from Bertha Benz, who used chemist shops to purchase the gasoline for her famous drive from Mannheim to Pforzheim in 1888, but from the chemical benzene.
Etymology
Gasoline is produced in oil refineries. Material that is separated from crude oil via distillation, called virgin or straight-run gasoline, does not meet the required specifications for modern engines (in particular octane rating; see below), but will form part of the blend.
The bulk of a typical gasoline consists of hydrocarbons with between 5 and 12 carbon atoms per molecule.
Many of these hydrocarbons are considered hazardous substances and are regulated in the United States by OSHA. The MSDS (Material Safety Data Sheet) for unleaded gasoline shows at least fifteen hazardous chemicals occurring in various amounts from 5% to 35% by volume of gasoline. These include benzene (up to 5% by volume), toluene (up to 35% by volume), naphthalene (up to 1% by volume), trimethylbenzene (up to 7% by volume), MTBE (up to 18% by volume) and about 10 others. Ref: (Tesoro Petroleum Companies, Inc.)
The various refinery streams blended together to make gasoline all have different characteristics. Some important streams are:
(The terms used here are not always the correct chemical terms. They are the jargon normally used in the oil industry. The exact terminology for these streams varies by refinery and by country.)
Overall a typical gasoline is predominantly a mixture of paraffins (alkanes), naphthenes (cycloalkanes), aromatics and olefins (alkenes). The exact ratios can depend on
Currently many countries set tight limits on gasoline aromatics in general, benzene in particular, and olefins (alkene) content. This is increasing the demand for high octane pure paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing units to reduce the benzene content.
Gasoline can also contain some other organic compounds: such as organic ethers (deliberately added), plus small levels of contaminants, in particular sulfur compounds such as disulfides and thiophenes. Some contaminants, in particular thiols and hydrogen sulfide, must be removed because they cause corrosion in engines.
Reformate, produced in a catalytic reformer with a high octane rating and high aromatic content, and very low olefins (alkenes).
Cat Cracked Gasoline or Cat Cracked Naphtha, produced from a catalytic cracker, with a moderate octane rating, high olefins (alkene) content, and moderate aromatics level. Here, "cat" is short for "catalyst".
Hydrocrackate (Heavy, Mid, and Light), produced from a hydrocracker, with medium to low octane rating and moderate aromatic levels.
Virgin or Straight-run Naphtha (has many names), directly from crude oil with low octane rating, low aromatics (depending on the crude oil), some naphthenes (cycloalkanes) and no olefins (alkenes).
Alkylate, produced in an alkylation unit, with a high octane rating and which is pure paraffin (alkane), mainly branched chains.
Isomerate (various names) which is obtained by isomerising the pentane and hexane in light virgin naphthas to yield their higher octane isomers.
the oil refinery that makes the gasoline, as not all refineries have the same set of processing units.
the crude oil used by the refinery on a particular day.
the grade of gasoline, in particular the octane rating. Volatility
For more details on this topic, see octane rating. Octane rating
World War II Germany received much of its oil from Romania. From 2.8 million barrels in 1938, Romania's exports to Germany increased to 13 million barrels by 1941, a level that was essentially maintained through 1942 and 1943, before dropping by half, due to Allied bombing and mining of the Danube. Although these exports were almost half of Romania's total production, they were considerably less than what the Germans expected. Even with the addition of the Romanian deliveries, overland oil imports after 1939 could not make up for the loss of overseas shipments. In order to become less dependent on outside sources, the Germans undertook a sizable expansion program of their own meager domestic oil pumping. After 1938, the Austrian oil fields were made available and the expansion of Nazi crude oil output was chiefly concentrated there. Primarily as a result of this expansion, the Reich's domestic output of crude oil increased from approximately 3.8 million barrels in 1938 to almost 12 million barrels in 1944. Even this was not enough.
Instead, Germany had developed a synthetic fuel capacity that was intended to replace imported or captured oil. Fuels were generated from Coal, using either the Bergius process or the Fischer-Tropsch process. Between 1938 and 1943, synthetic fuel output underwent a respectable growth from 10 million barrels to 36 million. The percentage of synthetic fuels compared with the yield from all sources grew from 22 percent to more than 50 percent by 1943. The total oil supplies available from all sources for the same period rose from 45 million barrels in 1938 to 71 million barrels in 1943.
By the early 1930s, automobile gasoline had an octane reading of 40 and aviation gasoline of 75-80. Aviation gasoline with such high octane numbers could only be refined through a process of distillation of high-grade petroleum. Germany's domestic oil was not of this quality. Only the additive tetra-ethyl lead could raise the octane to a maximum of 87. The license for the production of this additive was acquired in 1935 from the American holder of the patents, but without high-grade Romanian oil even this additive was not very effective.
In the US the oil was not "as good" and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits: the US industry started delivering fuels of increasing octane ratings by adding more of the boosting agents and the infrastructure was in place for a post-war octane agents additive industry. Good crude oil was no longer a factor during wartime and by war's end, American aviation fuel was commonly 130 to 150 octane. This high octane could easily be used in existing engines to deliver much more power by increasing the pressure delivered by the superchargers. The Germans, relying entirely on "good" gasoline, had no such industry, and instead had to rely on ever-larger engines to deliver more power.
However, German aviation engines were of the direct fuel injection type and could use methanol-water injection and nitrous oxide injection, which gave 50% more engine power for five minutes of dogfight. This could be done only five times or after 40 hours run-time and then the engine would have to be rebuilt. Most German aero engines used 87 octane fuel (called B4), while some high-powered engines used 100 octane (C2/C3) fuel.
This historical "issue" is based on a very common misapprehension about wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being always greater. So, for example, a common British aviation fuel of the later part of the war was 100/125. The misapprehension that German fuels have a lower octane number (and thus a poorer quality) arises because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number for their fuels. Standard German high-grade aviation fuel used in the later part of the war (given the designation C3) had lean/rich octane numbers of 100/130. The Germans would list this as a 100 octane fuel while the Allies would list it as 130 octane.
After the war the US Navy sent a Technical Mission to Germany to interview German petrochemists and examine German fuel quality. Their report entitled Technical Report 145-45 Manufacture of Aviation Gasoline in Germany chemically analyzed the different fuels and concluded that "Toward the end of the war the quality of fuel being used by the German fighter planes was quite similar to that being used by the Allies".
World War II and octane ratings
Gasoline contains about 34.6 megajoules per litre (MJ/l) or 131 MJ/US gallon. This is an average, gasoline blends differ, therefore actual energy content varies from season to season and from batch to batch, as much as 4% more or less than the average, according to the US EPA.
Volumetric energy density of some fuels compared with gasoline:.
Different countries have some variation in what RON (Research Octane Number) is standard for gasoline, or petrol. In the UK, ordinary regular unleaded petrol is 91 RON (not commonly available), premium unleaded petrol is always 95 RON, and super unleaded is usually 97-98 RON. However both Shell and BP produce fuel at 102 RON for cars with hi-performance engines, and the supermarket chain Tesco began in 2006 to sell super unleaded petrol rated at 99 RON. In the US, octane ratings in fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 (94-95) for mid-grade (European Premium), up to 90-94 (RON 95-99) for premium unleaded or E10 (Super in Europe)
Energy content
The U.S. used about 521 billion litres (137 billion gallons) of gasoline in 2006, of which 5.6% was mid-grade and 9.5% was premium grade.
Usage
World War II Germany received much of its oil from Romania. From 2.8 million barrels in 1938, Romania's exports to Germany increased to 13 million barrels by 1941, a level that was essentially maintained through 1942 and 1943, before dropping by half, due to Allied bombing and mining of the Danube. Although these exports were almost half of Romania's total production, they were considerably less than what the Germans expected. Even with the addition of the Romanian deliveries, overland oil imports after 1939 could not make up for the loss of overseas shipments. In order to become less dependent on outside sources, the Germans undertook a sizable expansion program of their own meager domestic oil pumping. After 1938, the Austrian oil fields were made available and the expansion of Nazi crude oil output was chiefly concentrated there. Primarily as a result of this expansion, the Reich's domestic output of crude oil increased from approximately 3.8 million barrels in 1938 to almost 12 million barrels in 1944. Even this was not enough.
Instead, Germany had developed a synthetic fuel capacity that was intended to replace imported or captured oil. Fuels were generated from Coal, using either the Bergius process or the Fischer-Tropsch process. Between 1938 and 1943, synthetic fuel output underwent a respectable growth from 10 million barrels to 36 million. The percentage of synthetic fuels compared with the yield from all sources grew from 22 percent to more than 50 percent by 1943. The total oil supplies available from all sources for the same period rose from 45 million barrels in 1938 to 71 million barrels in 1943.
By the early 1930s, automobile gasoline had an octane reading of 40 and aviation gasoline of 75-80. Aviation gasoline with such high octane numbers could only be refined through a process of distillation of high-grade petroleum. Germany's domestic oil was not of this quality. Only the additive tetra-ethyl lead could raise the octane to a maximum of 87. The license for the production of this additive was acquired in 1935 from the American holder of the patents, but without high-grade Romanian oil even this additive was not very effective.
In the US the oil was not "as good" and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits: the US industry started delivering fuels of increasing octane ratings by adding more of the boosting agents and the infrastructure was in place for a post-war octane agents additive industry. Good crude oil was no longer a factor during wartime and by war's end, American aviation fuel was commonly 130 to 150 octane. This high octane could easily be used in existing engines to deliver much more power by increasing the pressure delivered by the superchargers. The Germans, relying entirely on "good" gasoline, had no such industry, and instead had to rely on ever-larger engines to deliver more power.
However, German aviation engines were of the direct fuel injection type and could use methanol-water injection and nitrous oxide injection, which gave 50% more engine power for five minutes of dogfight. This could be done only five times or after 40 hours run-time and then the engine would have to be rebuilt. Most German aero engines used 87 octane fuel (called B4), while some high-powered engines used 100 octane (C2/C3) fuel.
This historical "issue" is based on a very common misapprehension about wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being always greater. So, for example, a common British aviation fuel of the later part of the war was 100/125. The misapprehension that German fuels have a lower octane number (and thus a poorer quality) arises because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number for their fuels. Standard German high-grade aviation fuel used in the later part of the war (given the designation C3) had lean/rich octane numbers of 100/130. The Germans would list this as a 100 octane fuel while the Allies would list it as 130 octane.
After the war the US Navy sent a Technical Mission to Germany to interview German petrochemists and examine German fuel quality. Their report entitled Technical Report 145-45 Manufacture of Aviation Gasoline in Germany chemically analyzed the different fuels and concluded that "Toward the end of the war the quality of fuel being used by the German fighter planes was quite similar to that being used by the Allies".
World War II and octane ratings
Gasoline contains about 34.6 megajoules per litre (MJ/l) or 131 MJ/US gallon. This is an average, gasoline blends differ, therefore actual energy content varies from season to season and from batch to batch, as much as 4% more or less than the average, according to the US EPA.
Volumetric energy density of some fuels compared with gasoline:.
Different countries have some variation in what RON (Research Octane Number) is standard for gasoline, or petrol. In the UK, ordinary regular unleaded petrol is 91 RON (not commonly available), premium unleaded petrol is always 95 RON, and super unleaded is usually 97-98 RON. However both Shell and BP produce fuel at 102 RON for cars with hi-performance engines, and the supermarket chain Tesco began in 2006 to sell super unleaded petrol rated at 99 RON. In the US, octane ratings in fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 (94-95) for mid-grade (European Premium), up to 90-94 (RON 95-99) for premium unleaded or E10 (Super in Europe)
Energy content
The U.S. used about 521 billion litres (137 billion gallons) of gasoline in 2006, of which 5.6% was mid-grade and 9.5% was premium grade.
Usage
Stability
No comments:
Post a Comment