Naphtha reformers atmospheres

The previous example was a rather unique application and not a typical case for fluidization. Although some fluidized bed reactions are executed at elevated pressure, like the naphtha reforming, most are used at atmospheric or at low pressures. The proceeding conceptual sketch. Figure 8.2.4, gives the most important features of a fluid-bed, cataljdic reactor. 

A combination unit is a special type of unit that was developed to reduce the investment for a small refinery. In effect, one main distillation unit serves as a crude fi-actionator as well as the cat unit primary fractionator. This same tower also serves the naphtha reformer and visbreaker. A schematic diagram of a combination unit is shown in Figure 2. Crude oil is topped (material boiling below 650°F is removed) in the atmospheric tower, and the topped crude is sent to the combination tower along with cat products and naphtha reformer products. These latter streams provide heat to distill the topped crude and also, being more volatile than topped crude, provide a lifting effect which assists in vaporizing more of the crude. 

Liquid feedstocks for olefin production are light naphtha, full range naphtha, reformer raffinate, atmospheric gas oil, vacuum gas oil, residues, and crude oils. The ratio of olefins produced from steam cracking of these feeds depends mainly on the feed type and, to a lesser extent, on the operation variables. For example, steam cracking light naphtha produces about twice the amount of ethylene obtained from steam cracking vacuum gas oil under nearly similar conditions. Liquid feeds are usually... 

As seen in Figure 2.2 and from the corresponding discussion, dehydrocyclization is a key reaction in forming aromatic compounds.307 A study comparing dehydrocyclization over mono- and bifiinctional catalysts at atmospheric pressure and high pressure representative of naphtha reforming conditions concludes that primary aromatic products at all pressures are formed by direct six-carbon ring formation.313 Over bifunctional catalysts the acid-catalyzed cyclization is more rapid... 

The new developments in catalyst improvements and in process optimization have brought new opportunities to directly process virgin naphtha from atmospheric distillation along with benzene and benzene precursors extracted from reformer feeds. This can eliminate the need for a separate naphtha hydrotreater as well as sepa-... 

The studies reviewed here focus on Sn/Pt because of the opportunity afforded by the ordered alloys formed in this system for improving our basic understanding, as well as the commercial importance of Pt-Sn catalysts in naphtha reforming and their potential for other selective hydrogenation and dehydrogenation reactions. These studies combined detailed structural characterization of the alloy surfaces with UHV studies of adsorption and reaction of hydrocarbons and other small molecules, and measurements of the rate and selectivity of catalytic reactions at atmospheric pressure over these model catalysts. 

Naphtha reformers operate in a hydrogen-rich atmosphere at temperatures around 535°C (1000°F) and at pressures up to 2 MPa (300 psi). Figure 10 is a cross... 

The feed to a catalytic reformer is normally a heavy naphtha fraction produced from atmospheric distillation units. Naphtha from other sources such as those produced from cracking and delayed coking may also be used. Before using naphtha as feed for a catalytic reforming unit, it must be hydrotreated to saturate the olefins and to hydrodesulfurize... 

A unique steam reforming process [495]-[497] has been developed in Japan to the pilot-plant stage. It reportedly can operate without upstream desulfurization and should be able to gasify naphtha, crude oil, and atmospheric or vacuum residues. 

Hydrotreating is being employed extensively in the petroleum industry for processing a variety of feedstocks. Both straight-run and cracked petroleum products such as naphthas, kerosenes, middle distillates, gas oils (atmospheric and heavy vacuum types), cycle stocks, residues, asphalts, crudes, and shale oils may be so treated. The process primarily is employed as a pretreat previous to catalytic reforming or catal3d ic cracking. 

Heavy straight-run (HSR) naphtha gained from atmospheric distillation and from vacuum distillation, followed by thermal, catalytic, or hydrocracking, is fed into a catalytic reformer to become reformate. 

Atmospheric distillation also yields lower-boiling heavy straight-run (HSR) gasoline (or HSR naphtha). Often after hydrotreating, this fraction is processed further at the catalytic reformer. 

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