Gasoline stabilization

Reid vapor pressure, bar Vapor pressure crude oil, bar Vapor pressure gasoline, bar R crude oil R stabilized gasoline... 

Oxidation stability (gasoline) (induction period) NFM 07-012 ISO/DlS 7536 ASTM D 525 Time necessary for a sample bomb under oxygen pressure to reach the critical induction point... 

The fat oil is fed to a splitter or stripping tower, where the absorbed tight constituents are separated from the oil by distillation. Usually the lean oil is the same material as the heavier part of the absorber feed, so that the bottoms from the stripper are split into lean oil, which is recycled to the absorber, and a stabilized gasoline product, which is passed on to subsequent processing operations. 

The debutanizer separates the feed into two products. The overhead product contains a mixture of C3 s and C4 s. The bottoms product is the stabilized gasoline. Heat for separating these products comes from an external reboiler. The heating source is usually the main fractionator heavy cycle oil or slurry. Steam can also be used. 

Gasoline-stabilization Example. As a further illustration of the use of these methods, a gasoline-stabilization operation will be considered. The feed composition is given in the table on this page and the tower is to operate at 250 p.s.i.g. A reflux ratio of 2 will be used in the upper portion of the tower, and the feed will enter such that below the feed will be 1.5. It is desired to recover 96 per cent of the normal butane with the stabilized gasoline, but this bottoms product is to contain not over 0.25 mol per cent propane. 

Liquids. The general composition of raw and stabilized gasolines, bottle gases, and distillates (or condensates) is drown in Table 22-6 and of pressure distillates in Table 7-2. Similar information about crude oils is shown in Table 4-5. The compositions of distillates or condensates from cycling plants (items 21 to 25, Table 22-6) are of little significance because of the wide range of pressure and temperature maintained, and because the liquid recovery is often reported as several products such as hydrocarbon liquids, distillate, and even kerosene. 

Figure 5.102 shows the stream configuration for the primary gasoline stabilizer. The overhead gas contains mostly light C1-C2 components that did not leave the Net H2 stream. The overhead liquid draw is mostly C3-C4 components which form an LPG like stream. The bottoms stream represents the stabilized gasoline or aromatic enriched liquid product from the reformer. 

Applied to atmospheric residue, its purpose is to produce maximum diesel oil and gasoline cuts while meeting viscosity and thermal stability specifications for industrial fuels. 

Detergent Additives. Diesel engine deposits ate most troublesome in the fuel dehvery system, ie, the fuel pump and both fuel side and combustion side of the injectors. Small clearances and high pressures mean that even small amounts of deposits have the potential to cause maldistribution and poor atomization in the combustion chamber. The same types of additives used in gasoline ate used in diesel fuel. Low molecular weight amines can also provide some corrosion inhibition as well as some color stabilization. Whereas detergents have been shown to be effective in certain tests, the benefit in widespread use is not fully agreed upon (77). 

Naphthalenol also is used ia the preparation of azo, iadigoid, and nitro, eg, 2,4-dinitro-l-naphthol, dyes, and ia making dye iatermediates, eg, naphtholsulfonic acids, 4-chloro-1-naphthalenol, and l-hydroxy-2-naphthoic acid. 1-Naphthalenol is an antioxidant for gasoline, and some of its alkylated derivatives are stabilizers for plastics and mbber (68). 

Stabilization of Fuels and Lubricants. Gasoline and jet engine fuels contain unsaturated compounds that oxidize on storage, darken, and form gums and deposits. Radical scavengers such as 2,4-dimethyl-6-/ f2 butylphenol [1879-09-0] 2,6-di-/ f2 -butyl-/)-cresol (1), 2,6-di-/ f2 -butylphenol [128-39-2], and alkylated paraphenylene diamines ate used in concentrations of about 5—10 ppm as stabilizers. 

Cresylic acid is mainly used as degreasing agent and as a disinfectant of a stabilized emulsion in a soap solution. Cresols are used as flotation agents and as wire enamel solvents. Tricresyl phosphates are produced from a mixture of cresols and phosphorous oxychloride. The esters are plasticizers for vinyl chloride polymers. They are also gasoline additives for reducing carbon deposits in the combustion chamber. 

Sodium decreases the hydrothermal stability of the zeolite. It also reacts with the zeolite acid sites to reduce catalyst activity. In the regenerator, sodium is mobile. Sodium ions tend to neutralize the strongest acid sites. In a dealuminated zeolite, where the UCS is low (24.22°A to 24.25°A), the sodium can have an adverse affect on the gasoline octane (Figure 3-7). The loss of octane is attributed to the drop in the number of strong acid sites. 

Hydrogen transfer reactions usually increase gasoline yield and stability. The reactivity of the gasoline is reduced because hydrogen transfer produces fewer olefins. 

The overhead stream from the debutanizer or stabilizer is a mix of C, s and C4 s, usually referred to as LPG (liquefied petroleum gas). It is rich in olefins, propylene, and butylene. These light olefins play an important role in the manufacture of reformulated gasoline (RFG). Depending on the refinery s configuration, the cat cracker s LPG is used in the following areas ... 

Rare Earth is a generic name used for the 14 metallic elements of the lanthanide series used in the manufacturing of FCC catalyst to improve stability, activity, and gasoline selectivity of the zeolite. 

The polyether imides show much better hydrolytic stability with little change in tensile strength after exposure to water at 100°C for 1 year. These materials also show exceptional resistance to mineral acids, and are unharmed by most hydrocarbons including gasoline (petrol) and oils. 

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