Feed characterization

Crude oil is a mixture of enormous variety of hydrocarbons derived from multiple sources and it contains hundreds of thousands of different molecules. As a result, we generally do not deal with crude in terms of molecular composition, especially in the case of the crude fractionation. We indicate the composition of crude (and refined hydrocarbon products) in terms of bulk properties and distillation-based properties. 

Brdk properties refer to properties measured while taking the whole crude into account. These properties are typically density, viscosity, refractive index, etc. and are useful but do not sufficiently define the crude or a cut from this crude. DistiUation-based properties refer to the bulk properties measured for small amounts of crude based on that small amount s boiling point Typically, we present these properties as a function of these small amounts as density distributions, boiling points distributions (TBP, D-86, D-2887), etc. When a refiner considers particular crude for use, the collection of bulk and distillation based properties form particular crude s assay. This assay indicates how much of a given cut (or product) we can produce from a given crude. Tables 2.5 to 2.8 show crude assays for Arab Heavy and Arab Light crude. 

---

An important part of any cat crackings correlations package is an accurate feed characterization technique. Feed characterization is vital since it quantifies... 

Feed characterization is the process of determining the physical and chemical properties of the feed. Two feeds with similar boiling point ranges may exhibit dramatic differences in cracking performance and product yields. 

FCC feed characterization is one of the most important activities in monitoring cat cracking operation. Understanding feed properties and knowing their impact on unit performance are essential. Troubleshooting, catalyst selection, unit optimization, and subsequent process evaluation all depend on the feedstock. 

Feed characterization relates product yields and qualities to feed quality. Knowing the effects of a feedstock on unit yields, a refiner can purchase the feedstock that maximizes profitability. It is not uncommon for refiners to purchase raw crude oils or FCC feedstocks without knowing their impact on unit operations. This lack of knowledge can be expensive. 

The feed characterization correlations discussed in Chapter 2 should be used to determine the composition of fresh feed. 

In the previous examples, the feed characterizing correlations in Chapter 2 are used to determine composition of the feedstock. The results show that the feedstock is predominantly paraffinic (i.e., 61.6% paraffins. 19.9% naphthenes, and 18.5% aromatics). Paraffinic feedstocks normally yield the most gasoline with the least octane. This confirms the relatively high FCC gasoline yield and low octane observed in the test run. This is the kind of information that should be included in the report. Of course, the effects of other factors, such as catalyst and operating parameters, will also affect the yield structure and will be discussed. 

Pet foods Ruminant feeds Feedback control, purpose of, 20 666 Feedback controllers, 20 666-667 tuning and stability of, 20 694 Feedback control systems, 20 691-695 Feedback loops, between science and technology, 21 615 Feed-back system, closed loop fuel metering system, 10 56 Feed characterization, in reverse osmosis, 21 666... 

X = Feed characterization factor X2 = Liquid volume percent conversion X3 = Feed API X4 = Feed sulfur content... 

Chesson, A. (2000) Feed characterization. In Theodorou, M.K. and France, J. (eds) Feeding Systems and Feed Fvaluation Models. CAB International, Wallingford, UK, pp. 11-33. 

Application of H-NMR for Fluid Catalytic Cracking Feed Characterization... 

Some of the feed characterization procedures were conducted in the Resonance Magnetic Nuclear Laboratory at the National University in Colombia. In particular, the authors would like to thank Dr. Ricardo Fierro and Eliseo Abella for performing H-NMR analyses, and Dr. Carlos A. Trujillo for the UV-Vis analyses of the feeds. 

Feed characterization, particularly for nondesalination applications, should be the first and foremost objective in the design of a reverse osmosis plant. This involves the determination of the type and concentration of the main solutes and foulants in the stream, temperature, pH, osmotic pressure, etc. Once the feed has been characterized, a realistic process objective can be defined. In most cases, some level of pretreatment is needed to reduce the number and concentration of foulants present in the feed stream. Pretreatment necessitates the design of processes other than the RO module, thus the overall process design should use the minimum pretreatment necessary to meet the process objective. Once the pretreatment steps have been determined and the final feed stream defined, the RO module can be selected. 

Saraf, A. V., Silerman, M. A., and Ross, J. L. FCC Modeling Based on Advanced Feed Characterization Techniques, in Circulating Fluidized Bed Technology IV (Amos A. Avidan, ed.), pp. 559-564. Somerset, Pennsylvania (1993). 

At this point, the yield model can be used to represent the pyrolysis behavior of specific feedstocks. To generalize the model, the effect of feed properties must be incorporated. Naphthas are complex mixtures of hydrocarbons. Feed characterization is needed to condense a detailed naphtha description into a manageable set of parameters, which uniquely defines feed-dependent conversion and yield effects. 

---