Middle distillate

Middle distillate
other names	straight-run , medium oil, blue oil or green oil, vacuum gas oil
Brief description	Distillates (petroleum), straight-run medium, distillates (petroleum), solvent-processed medium
CAS number	64741-44-2 64741-91-9
properties
Physical state	liquid
viscosity	2–8 mm² / s (20 ° C)
Cetane number	40-60 CZ
Boiling range	240 ° C
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 304 P: 301 + 310-331-405-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Middle distillate is the name given to the products that are obtained from the refining of crude oil in the "medium" boiling range (140 ° C to 370 ° C). They come in two primary fractions as kerosene (petroleum) with a boiling range of 140–250 ° C and gas oil with a boiling range of around 250–350 ° C. These include light heating oil , diesel fuel and Jet A1 .

Components that are obtained from the middle fume cupboards during the rectification of a multi-substance mixture are also referred to as middle distillates (e.g. kerosene , light gas oil, heavy gas oil).

composition

In the middle distillates, the alkanes form the main component with 70–80%, among them the naphthenes with 20–25% and the iso-paraffins. In the aromatic fraction (20–30%) the alkylbenzenes predominate (up to about 15%), followed by the alkylnaphthalenes . The indanes ( benzene nucleus condensed with cyclopentane ) are also clearly represented at 4–6%. In middle distillates one finds alkylbenzenes, alkylnaphthalenes and alkylanthracenes . The symmetrical C distribution around C ₁₈ to C ₂₀ corresponding to the distillation cut of the middle distillates can also be shown from mass spectroscopic investigations . Indane and indene of the same settlement area are present as accompanying substances.

Composition of a middle distillate

links	Weight%
n- and iso-alkanes	50-53
Monocyclic alkanes	10-16
Dicyclic alkanes	6-9
Tetracyclic alkanes	1.5-4
Alkylbenzenes	4-12
Indane, tetraline	4-6
Indene	0.5-1.5
naphthalene	0.1-0.2
Alkyl naphthalenes	7-9
Acenaphthenes	0.5-1.5
Tricyclic aromatics	0.1-0.9

Obtaining the middle distillates in crude oil distillation

Various raw materials are obtained from the distillation of crude oil . The crude oil heated by the tube furnace flows into the distillation tower (also known as the distillation column). This contains a large number of soils in which temperatures drop from bottom to top. As soon as the oil vapors rise, they cool down and condense. Depending on the boiling temperature, this happens on different trays of the column. The middle distillates are drawn off from the distillation column through side draws. Heavy gas oil is drawn off just above the crude oil inlet into the column, light gas oil is drawn off a few floors above, kerosene just below the top of the column. In the subsequent side strippers , slight fractions may be removed from the respective middle distillate fraction. This increases the flash point of the respective component.

Construction of a main separation column in oil refining

(The complete structure is described under the entry Petroleum Refinery.)

• The top fraction is fed into the overpressure separation column, in which refinery gas, liquefied gases and gasoline are obtained.
• The first side draw is fed into the first side stripper, where kerosene is produced.
• The second and third side draws are the middle distillate draws, which are fed into the second and third side strippers. This is where the gas oil fractions are obtained.
• The bottom fraction is either used directly as heavy fuel oil or is separated into bitumen and vacuum gas oil in vacuum distillation .

Individual evidence

1. ↑ Prevention plan for combating hazardous substances accidents : Control manual, Chapter 5.1.2 Viscosity ( Memento of the original from October 9, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. : Viscosities of the main oil products, accessed October 9, 2016. 
2. ↑ ^{a b c} Safety data sheet  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
3. ↑ Rüdiger Düsing: Multidimensional fluorescence spectroscopy in environmental analysis . Herbert Utz Verlag, 2002, ISBN 978-3-8316-0092-2 , p. 5 ( limited preview in Google Book search).
4. ↑ Jochen Latz: Desulfurization of middle distillates for use in mobile fuel cell systems . Forschungszentrum Jülich, 2008, ISBN 978-3-89336-535-7 , p. 7 ( limited preview in Google Book search).
5. ^ ^{A b} Hubert Hellmann: Environmental analysis of hydrocarbons . John Wiley & Sons, 2009, ISBN 3-527-62445-7 , pp. 9 ( limited preview in Google Book search).