Gas oil yields

The yields and product distribution obtained in delayed coking are functions of the character of the feed stock and the operating conditions. Gas oil yields of 60 to 85 volume % with coke yields of 10 to 30 weight % of the feed are reasonably representative 5). 

Table VIL Hydrocracking of Heavy Gas Oil. Yield Structure for the 3.1% Pd Omega Catalyst ...

Z 2. =L ft P lys 3 1 r ft -s 0 i l RUN NO. Monarch (Lower Bench, 74-53) Effect of Reaction Time on Conversion and Oil Yield with CONTACT TIME, TEMPERATURE, CONVERSION, MINUTES °C PRESSURE, osle PERCENT Synthesis Gas OIL YIELD, PERCENT VISCOSITY AT 60°C CD... 

The overhead oil is fractionated into fuel gas (ethane and lower-molecular-weight gases), propane-propylene, butane-butene, naphtha, light gas oil, and heavy gas oil. Yields and product quality vary widely because of the broad range of feedstock types charged to delayed coking. The function of the coke drum is to provide the residence time required for the coking reactions and to accumulate the coke. Hydraulic cutters are used to remove coke from the drum. 

This section reviews examples of results obtained from the catalytic cracking runs conducted in the Riser Simulator. These runs show the ability of the Riser Simulator to assess catalyst performance. First, the trends in conversion of gas oils, yields of products and gasoline research octane numbers will be discussed for both the commercial feedstocks and for the pure light oil mixtures used. Then the kinetic parameters obtained from the 3-lump model and an 8-lump model using various decay functions are presented. Additional details about product distribution are provided in Kraemer (1991). 

Gas 0/7-all distillates heavier than heavy distillate. Gas oil yielded from the atmospheric tower will have ASTM end points of approximately 800 degrees F. Vacuum gas oils will have ASTM end points as high as 1,100 degrees F. Depending upon the operation being practiced, vacuum gas oils can have various boiling ranges. This subject is covered in detail in Chapter 3. 

Heavy cycle oil has the same general ASTM boiling range—say, 700 to 900 degrees F—as the combined atmospheric and vacuum gas oils yielded from a crude unit. This stream is almost invariably recycled to the reactor and cracked to extinction. Hence, facilities for cutting HCO into separate fractions are seldom required. 

For a single stage separator i.e. only one separator vessel, there is an optimum pressure which yields the maximum amount of oil and minimises the carry over of heavy components into the gas phase (a phenomenon called stripping). By adding additional separators to the process line the yield of oil can be increased, but with each additional separator the incremental oil yield will decrease. 

The feedstocks used ia the production of petroleum resias are obtaiaed mainly from the low pressure vapor-phase cracking (steam cracking) and subsequent fractionation of petroleum distillates ranging from light naphthas to gas oil fractions, which typically boil ia the 20—450°C range (16). Obtaiaed from this process are feedstreams composed of atiphatic, aromatic, and cycloatiphatic olefins and diolefins, which are subsequently polymerized to yield resias of various compositioas and physical properties. Typically, feedstocks are divided iato atiphatic, cycloatiphatic, and aromatic streams. Table 2 illustrates the predominant olefinic hydrocarbons obtained from steam cracking processes for petroleum resia synthesis (18). 

The principal route for production of isoprene monomer outside of the CIS is recovery from ethylene by-product C streams. This route is most viable where ethylene is produced from naphtha or gas oil and where several ethylene plants are located in relatively close proximity to the isoprene plant. Although the yield of isoprene per mass of ethylene is quite low, there is enough ethylene produced to provide a large portion of demand. Because of the presence of / -pentane in these streams which a2eotropes with isoprene, extractive distillation must be used to recover pure isoprene. Acetonitrile is the most common solvent, but dimethylformamide is also used commercially. 

Temperature and Product Yields. Most oil shale retorting processes are carried out at ca 480°C to maximize liquid product yield. The effect of increasing retort temperature on product type from 480 to 870°C has been studied using an entrained bed retort (17). The oil yield decreased and the retort gas increased with increased retorting temperature the oil became more aromatic as temperature increased, and maximum yields of olefinic gases occurred at about 760°C. Effects of retorting temperatures on a distillate fraction (to 300°C) are given in Table 6. 

As is indicated in Figure 4, saturates contribute less to the vacuum gas oil (VGO) than the aromatics, but more than the polars present at percentage, rather than trace, levels. VGO itself is occasionally used as a heating oil but most commonly it is processed by catalytic cracking to produce naphtha or by extraction to yield lubricant oils. 

Conrad Industries, Inc. (CentraUa, Washington) and Clean Air Products Company (Pordand, Oregon) have jointiy built a tire pyrolysis demonstration machine which allows recovery of combustible gases, oils, and other by-products. The equipment can also handle other carbonaceous material. It is designed to process 0.9 t/h of tires the entire system is estimated to cost about 2.3 x 10 . The feedstock consists of 5-cm tires chips which produce pyrolytic filler, a vapor gas yielding 11.5 kj/m (1000 Btu/ft ), and medium and light oils yielding about 42 MJ/kg (18,000 Btu/lb) (32). 

Both alkanes and gas oil can be used as carbon and energy sources. Commercially, Candida tropicalis and Candida lipolytica have been used (35,36). The fermentation contains two immiscible Hquid phases (the alkane and the water) the semisoHd yeast and the gaseous air phase. In contrast to yeasts grown on carbohydrates, where maximum yields are 50%, yeasts grown on alkanes generally give yields of 95—105% based on the weight of the alkane. 

A large amount of BTX is obtained as a by-product of ethylene manufacture (see Ethylene). The amount produced strongly depends on the feed to the ethylene plant. This is illustrated in Table 3 for various feeds to a typical large scale plant producing 450,000 t/yr of ethylene (16). Note that only about 1—2% of the ethane/propane feeds end up as BTX and it is almost completely benzene and toluene. As the feed goes up in molecular weight, the yield of BTX increases from 4% with butane feed to about 10% with gas oils, and the BTX proportions go from 72 20 8 respectively, to 44 34 22 respectively. 

Butylene yield Gas oil Residue Delayed coking Elexicoking Steam cracking of naphtha... 

Significant products from a typical steam cracker are ethylene, propylene, butadiene, and pyrolysis gasoline. Typical wt % yields for butylenes from a steam cracker for different feedstocks are ethane, 0.3 propane, 1.2 50% ethane/50% propane mixture, 0.8 butane, 2.8 hill-range naphtha, 7.3 light gas oil, 4.3. A typical steam cracking plant cracks a mixture of feedstocks that results in butylenes yields of about 1% to 4%. These yields can be increased by almost 50% if cracking severity is lowered to maximize propylene production instead of ethylene. 

Butadiene yields ranging from 2 to 7 weight percent on feed (usually 4 to 5j are expected in the steam cracking of naphthas and gas oils. This is generally 35 to 45 percent of the total yield of C4 s. 

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