Stability naphtha

The solvent contained in the asphalt and deasphalted oil is condensed in the fractionator overhead condensers, where it can be recovered and used as lean oil for a propane/butane recovery in the absorber, eliminating the need for lean oil recirculation from the naphtha stabilizer. The solvent introduced in the coker heater and coke drums results in a significant reduction in the partial pressure of asphalt feed, compared with a regular delayed coking unit. The low asphalt partial pressure results in low coke and high liquid yields in the coking reaction. 

Clearly, hydrocracking is a complex process. To simplify the overall task of defining key indicators for the whole unit, we can divide it into three sections reaction, product fractionation, and debutanizer or naphtha stabihzer. The naphtha stabilizer section is not shown in Figure 4.1. The goal is to define a set of key indicators for each section, which can be used for monitoring and optimization. 

The main equipment in the naphtha stabilizer section is the debutanizer. Similar to the previous discussions, we can identify key indicators for the debutanizer column ... 

Actual partial condensers usually operate somewhere between Cases 1 and 2. For an absorption naphtha stabilizer, Gunness (Ref. 6) (see page 116) found good agreement with Case 2. In actual design calculation, the conservative assumption is to assume operation as in Case 1, and any fractionation that does occur will act as a factor of safety with ordinary condenser design, with the most optimistic assumption,... 

Figure 5.1. Whole naphtha stabilizer with vapor distillate.

The procedure applies to stabilized, i.e., debutanized, crudes, but can be applied to any petroleum mixture with the exception of liquefied petroleum gas, very light naphtha, and those fractions having boiling points over 400°C. 

Most catalyst supports are simply nearly inert platforms that help stabilize the dispersion of the catalyticaHy active phase. Sometimes, however, the supports play a direct catalytic role, as exemplified by the alumina used in supported Pt and RePt catalysts for naphtha reforming. 

A broad range of solvents can be used in solvent-borne BR and PIB adhesives. Hydrocarbon (hexane, heptane, naphtha) and chlorinated solvents (perchloroethy-lene) can be used they provide higher viscosities. The presence of small amounts of stabilizer may cause cloudy solutions and settling is rarely produced. There is a logarithmic relationship between viscosity and solids content. In fact, a small... 

Gas plants are integrated tower systems intended to recover LPG range material and separate it from naphtha products. This stabilizes the naphtha and reduces its vapor pressure. The LPG material may either be saturate gases going to LPG or unsaturates going to further processing. Gas plants on preflash and atmospheric crude processing units are saturate gas plants. Gas plants on FCC units are unsaturate gas plants. Coker and visbreaker gas plants are somewhere between the two. 

On cracked naphthas. Hydrofining provides not only desulfurization, but also improvements in gum, stability, and engine cleanliness characteristics. 

Hydrofining is employed to desulfurize high sulfur diesel stocks, both virgin and cracked. The stability of cracked diesel stocks is also improved. In the diesel range, operating conditions become more severe. Compared to naphthas, temperatures are increased from the 550-600°F level to 700°F. 

The virgin naphtha feed after having been hydrofined over a cobalt molybdenum catalyst to remove sulftir compounds passes through the Powerformer. After stabilization, the aromatics are recovered by extracdon with... 

Naphthas obtained from cracking units generally contain variable amounts of olefins, higher ratios of aromatics, and branched paraffins. Due to presence of unsaturated compounds, they are less stable than straight-mn naphthas. On the other hand, the absence of olefins increases the stability of naphthas produced by hydrocracking units. In refining operations, however, it is customary to blend one type of naphtha with another to obtain a required product or feedstock. 

The petroleum ether solvents are a specific-boiling-range naphtha, as is ligroin. Thus, the term petroleum solvent describes a special liquid hydrocarbon fraction obtained from naphtha and used in industrial processes and formulations (Weissermel and Arpe, 1978). These fractions are also referred to as industrial naphtha. Other solvents include white spirit, which is subdivided into industrial spirit [distilling between 30 and 200°C (86 to 392°F)] and white spirit [light oil with a distillation range of 135 to 200°C (275 to 392°F)]. The special value of naphtha as a solvent lies in its stability and purity. 

The demonstrated performance of ZSM-5 in over 35 cracking units is reviewed. The main features of ZSM-5 are its high activity and stability, favorable selectivity, metals tolerance and flexibility, particularly when used as an additive catalyst. ZSM-5 cracks and isomerizes low octane components in the naphtha produced by the faujasite cracking catalyst. As a result and olefins are produced and gasoline compositional changes occur which explain its increased research and motor octanes. A model was developed which predicts ZSM-5 performance in an FCC unit. 

Benzene, 50 parts may be gelled by adding potassium tridecylxanthate 3 parts naphtha 50 parts will further stabilize the gel. Possible uses are solid fuels, lubricants, military incendiaries hydraulic fractaring fluids. Addition of w, 3—5 S, will liquefy the gel... 

Two undesirable aspects of FCC naphtha quality are that it may contain unacceptably high amounts of foul smelling mercaptans, and that its thermal stability may be too low. Mercaptans are usually found in the light FCC naphtha and may be removed or converted to sulfides and disulfides by a sweetening process such as Merox, developed by UOP. Thermal stability is improved in sweetening processes through removal of cresylic and naphthenic acids. It may be further improved by clay treating and by addition of oxidation inhibitors such as phenylene diamine. 

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