Presentation on theme: "Chapter 2: Refinery Products Over 2000 individual products distributed in 17 classes as shown in table below:"— Presentation transcript:
Chapter 2: Refinery Products Over 2000 individual products distributed in 17 classes as shown in table below:
2.1 Low boiling Products The compounds which are in the gas phase at ambient temperatures and pressures: methane, ethane, propane, butane, and the corresponding oleﬁns. Methane (C1) is usually used as a reﬁnery fuel, but can be used as a feed- stock for hydrogen production by pyrolytic cracking and reaction with steam Ethane (C2) can be used as reﬁnery fuel or as a feedstock to produce hydro- gen or ethylene, which are used in petrochemical processes. Ethylene and hydro- gen are sometimes recovered in the reﬁnery and sold to petrochemical plants.
Continued….. Propane (C3) is frequently used as a reﬁnery fuel but is also sold as a liquiﬁed petroleum gas (LPG), whose properties are speciﬁed by the Gas Processors Association (GPA). In some locations, propylene is separated for sale to polypropylene manufacturers.
Continued ……. The butanes present in crude oils and produced by reﬁnery processes are used as components of gasoline and in reﬁnery processing as well as in LPG: Normal butane (nC4) has a lower vapor pressure than isobutane (iC4), and is usually preferred for blending into gasoline to regulate its vapor pressure and promote better starting in cold weather. Normal butane has a Reid vapor pressure (RVP) of 52 psi (358 kPa) as compared with the 71 psi (490 kPa) RVP of isobutane, and more nC4 can be added to gasoline without exceeding the RVP of the gasoline product Normal butane is also used as a feedstock to isomerization units to form isobutane. N-butane has a blending octane in the 90s and is a low-cost octane improver of gasoline
Continued….. Isobutane has its greatest value when used as a feedstock to alkylation units, where it is reacted with unsaturated materials (propenes, butenes, and pentenes) to form high-octane isoparafﬁn compounds in the gasoline boiling range Although isobutane is present in crude oils, its principal sources of supply are from ﬂuid catalytic cracking (FCC) and hydrocracking (HC) units in the reﬁnery and from natural gas processing plants. Isobutane not used for alkylation unit feed can be sold as LPG or used as a feedstock for propylene (propene) manufacture A signiﬁcant amount of isobutane is converted to isobutylene which is reacted with methanol to produce methyl tertiary butyl ether (MTBE). Butane–propane mixtures are also sold as LPG, and their properties and standard test procedures are also speciﬁed by the GPA
2.2 Gasoline 40 types of gasolines are made by reﬁneries, about 90% of the total gasoline produced in the United States is used as fuel in automobiles. Most reﬁners produce gasoline in two or three grades, un- leaded regular, premium, and super-premium, and in addition supply a regular gasoline to meet the needs of farm equipment and pre-1972 automobiles The principal difference between the regular and premium fuels is the antiknock performance. (PON) Posted octane numbers are arithmetic averages of the motor octane number (MON) and research octane number (RON) and average four to six numbers below the RON.
MON: the antiknock performance during loading and drive with acceleration RON: The antiknock performance during city drive
Gasolines are complex mixtures of hydrocarbons having typical boiling ranges from 100 to 400°F (38 to 205°C) Components are blended to promote high antiknock quality, ease of starting, quick warm-up, low tendency to vapor lock, and low engine deposits Components are: o Light straight-run (LSR) gasoline consists of the C5-190°F(C- 88°C) fraction of the naphtha cuts from the atmospheric crude still o Catalytic reformate is the C5 gasoline product of the catalytic reformer. The processing conditions of the catalytic reformer are controlled to give the desired product antiknock properties in the range of 90 to 104 RON (85 to 98 PON) clear (lead-free)
o The FCC and HC gasolines are generally used directly as gasoline blending stocks o Polymer gasoline is manufactured by polymerizing oleﬁnic hydrocarbons to produce higher molecular weight oleﬁns in the gasoline boiling range o Alkylate gasoline is the product of the reaction of isobutane with propylene, butylene, or pentylene to produce branched- chain hydrocarbons in the gasoline boiling range Reﬁnery technology favors alkylation processes rather than polymerization for two reasons: one is that larger quantities of higher octane product can be made from the light oleﬁns available, and the other is that the alkylation product is parafﬁnic rather than oleﬁnic
Alkylation of a given quantity of oleﬁns produces twice the volume of high octane motor fuel as can be produced by polymerization In addition, the blending octane (PON) of alkylate is higher and the sensitivity (RON MON) is signiﬁcantly lower than that of polymer gasoline. o Normal butane is blended into gasoline to give the desired vapor pressure. o MTBE (methyl tertiary butyl ether), ETBE (ethyl tertiary butyl ether), TAME (tertiary amyl methyl ether) and ethanol.
Field tests indicate that it is desirable to have gasoline sulfur contents of less than 300 ppm (0.03 wt%) For a given reﬁnery crude oil charge, to meet the 300 ppm sulfur speciﬁcation, with no octane penalty, it is necessary to hydrotreat the FCC feedstock to reduce the sulfur level sufﬁciently to produce FCC naphthas with acceptable sulfur contents. The alternative is to hydrotreat the FCC naphtha, but this saturates the oleﬁns in the naphtha and results in a blending octane reduction of two to three numbers
Some aromatics and most oleﬁns react with components of the atmosphere to produce visual pollutants. The activities of these gasoline components are ex- pressed in terms of reactivity with (OH) radicals in the atmosphere
GASOLINE SPECIFICATIONS Reid vapor pressure, boiling range, and antiknock characteristics. The Reid vapor pressure (RVP) and boiling range of gasoline governs ease of starting, engine warm-up, rate of acceleration, loss by crankcase dilution, mile- age economy, and tendency toward vapor lock Warm-up is expressed in terms of the distance operated to develop full power without excessive use of the choke. A two- to four-mile (3- to 7-km) warm-up is considered satisfactory
DISTILLATE FUELS JET AND TURBINE FUELS Jet fuel is blended for use by both commercial aviation and military aircraft For most reﬁneries the primary source of jet fuel blending stocks is the straight-run kerosine fraction from the atmospheric crude unit be cause stringent total aromatic and naphthalene content and smoke point speciﬁcations limit the amount of cracked stocks which can be included For reﬁneries with a hydrocracker, kerosine boiling range hydrocarbons from this unit can also meet jet fuel speciﬁcations and is a major contributor to jet fuel production
Commercial jet fuel is a material in the kerosine boiling range and must be clean burning Naphtha jet fuel is produced primarily for the military and is a wide- boiling-range stock which extends through the gasoline and kerosine boiling ranges.
AUTOMOTIVE DIESEL FUELS Volatility, ignition quality (expressed as cetane number or cetane index), viscosity, sulfur content, percent aromatics, and cloud point are the important properties of automotive diesel fuels No. 1 diesel fuel (sometimes called super-diesel) is generally made from virgin or hydrocracked stocks having cetane numbers above 45. It is has a boiling range from 360 to 600°F (182 to 316°C) and is used in high-speed engines in automobiles, trucks, and buses No. 2 diesel fuel is very similar to No. 2 fuel oil, and has a wider boiling range than No. 1. It usually contains cracked stocks and may be blended from naphtha, kerosine, and light cracked oils from the coker and the ﬂuid catalytic cracking unit. Limiting speciﬁcations are ﬂash point [125°F (52°C)], sulfur content (0.05% max.), distillation range, cetane number or cetane index (40 min.), percent aromatics, and cloud point
The ignition properties of diesel fuels are expressed in terms of cetane number or cetane index. These are very similar to the octane number (except the opposite) and the cetane number expresses the volume percent of cetane (C 16 H 34, high-ignition quality) in a mixture with alpha- methyl-naphthalene (C 11 H 10, low- ignition quality)
RAILROAD DIESEL FUELS Railroad diesel fuels are similar to the heavier automotive diesel fuels but have higher boiling ranges [up to 750°F (400°C) end point] and lower cetane numbers (30 min.). HEATING OILS
RESIDUAL FUEL OILS Composed of the heaviest parts of the crude and generally the fractionating tower bottoms from vacuum distillation. It sells for a very low price (historically about 70% of the price of crude from which it is produced) and is considered a by-product. Critical speciﬁcations are viscosity and sulfur content