Feedstock physical properties

Sulfur Content. Another important feedstock physical property related to delayed coking is the sulfur content. The sulfur present in the feedstock tends to concentrate in the coke, where the sulfur level is usually equal to or higher than that of the feedstock. Sulfur levels as high as 4 weight % in today s feedstocks can cause unacceptably high levels of sulfur in the coke product. The resulting coke may not be acceptable for metallurgical use and may be a problem when burned as fuel. 

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). 

Purification. The method used to recover the desired alkylphenol product from the reactor output is highly dependent on the downstream use of the product and the physical properties of the alkylphenol. The downstream uses vary enormously some require no refining of the alkylphenol feedstock others require very high purity materials. Physical property differences affect both the basic type of process used for recovery and the operating conditions used within that process. 

Characterizing an FCC feedstock involves determining both its chemical and physical properties. Because sophisticated analytical techniques, such as mass spectrometry, are not practical on a daily basis, physical properties are used. They provide qualitative measurement of the feed s composition. The refinery laboratory is usually equipped to carry out these physical property tests on a routine basis. The most widely used properties are ... 

Despite their flaws, batch processes have stood the test of time for a number of reasons, the most important of which is the flexibihty it brings to the manufacturer in terms of the range of products that the plant can produce, the feedstocks used to produce them, and the speed at which they can be brought to market with very limited information on physical properties, reaction kinetics, and so on (very few, if any, Michelin-starred chefs have ever measured the rheology or kinetics of their latest culinary creation). This flexibility, however, has a price which comes in the form of lower efficiencies in terms of production, energy, labor, and so on, and ultimately efficiency equates to cost However, one should never underestimate the pull of flexibility particularly, as discussed earlier in the examples of fermentation, where control of important parameters is difficult to achieve. 

Methylamines, 12 112 16 355-370 chemical properties of, 16 357-360 commercial, 16 356t economic aspects, specifications, and uses for, 16 364-368 end uses of, 16 365 exposure limits for, 16 3641 as feedstocks, 16 357-359 health, safety, and toxicology of, 16 364 manufacture of, 16 360-363 manufacturing data for, 16 367t physical properties of, 16 356-357 production of, 16 300 products manufactured using, 16 366-367t... 

The evaluation of petroleum must of necessity involve a study of composition because of the interrelationship of the physical properties and composition as part of the overall evaluation of different feedstocks. There are several ASTM procedures for feedstock/product evaluation ... 

Olefins plants, for the most part, all have the same basic technology, but the process flows differ with the varied feedstocks that can be used. This chapter will cover in some depth the feeds, the hardware, the reactions, and the variables that can be manipulated to change the amount and mix of products. The physical properties of ethylene and propylene, which present some unique handling problems, will be covered also. 

End uses. Its a little curious that the two major end uses for EG are so different. One is -a consumer product the other is a feedstock for more complicated chemistry. The reasons have to do with two separate properties of EG, one physical property, one chemical property. Because of EG s low freezing point, it is the main ingredient in automotive antifreeze. Because it is so chemically reactive, it is used as a monomer in making polyester polymers and PET, the plastic in the ubiquitous water and drink bottles. 

Feedstock Characterization. The feedstocks studied in this effort were a Wilmington vacuum gas oil and two hydrotreated products of this gas oil. The specific samples considered were sample No. 1693, an untreated Wilmington vacuum gas oil, a low severity hydrotreated product from sample No. 1693 (sample No. WM-2-2R, hydrotreated at 375° C, 1.5 LHSV, and 1500 psig), and a high severity hydrotreated product (sample No. WM-2-9, hydrotreated at 425° C, 0.5 LHSV, 1500 psig). The available physical properties for each of these feedstocks are given in Table I. 

During the last decade, there has been a definite trend towards heavier hydrocracker feedstocks (2). Recognition of the interactions between feed molecular weight and catalyst chemical and physical properties has been necessary to support this trend. 

Thus, initial inspection of the feedstock (conventional examination of the physical properties) is necessary. From this, it is possible to make deductions about the most logical means of refining. In fact, evaluation of crude oils from physical property data as to which refining sequences should be employed for any particular crude oil is a predominant part of the initial examination of any material that is destined for use as a refinery feedstock. 

Speight, 1999). Indeed, careful evaluation from physical property data is a major part of the initial study of any refinery feedstock. Proper interpretation of the data resulting from the inspection of crude oil requires an understanding of their... 

Of the data that are available, the proportions of the elements in petroleum vary only slightly over narrow limits (Chapter 1). And yet, there is a wide variation in physical properties from the lighter more mobile crude oils at one extreme to the heavier asphaltic crude oils at the other extreme. The majority of the more aromatic species and the heteroatoms occur in the higher boiling fractions of feedstocks. The heavier feedstocks are relatively rich in these higher boiling fractions. 

It must be emphasized that to proceed from the raw evaluation data to full-scale production is not the preferred step. Further evaluation of the processability of the feedstock is usually necessary through the use of a pilot-scale operation. To take the evaluation of a feedstock one step further, it may then be possible to correlate the data obtained from the actual plant operations (as well as the pilot plant data) with one or more of the physical properties determined as part of the initial feedstock evaluation. 

Standard analyses on whole heavy crude oil or residua, such as determinations of elemental compositions and various physical property tests (Chapter 2) have served to provide some indications of processability and may give an indication of the feedstock behavior. However, there is some question of the reliability of the tests when applied to the heavier feedstocks. For example, it might be wondered if the carbon residue tests (ASTM D-189, ASTM D-524, and ASTM D-4530) are really indicative of the yields of coke formed under process conditions. And, for the heavier feedstocks, it must be emphasized that to proceed from the raw evaluation data to full-scale production, insofar as the heavy feedstock is immediately used in the rehnery, is to proceed without caution. The thermal chemistry of the feedstock constituents will remain an unknown until the feedstock is used on-stream and the compatibility of the feedstock and the products with other feedstocks and products will also be unknown. Further evaluation of the processability of the feedstock is usually necessary. 

Residua and heavy oils contain impurities other than sulfur, nitrogen, and oxygen, and the most troublesome of these impurities are the organometallic compounds of nickel and vanadium. The metal content of a residuum or heavy oil can vary from several parts per million (ppm) to more than 1000 parts per million (Table 6-15), and there does seem to be more than a chance relationship between the metals content of a feedstock and its physical properties (Reynolds, 1997 Speight, 1999). In the hydrodesulfurization of the heavier feedstocks the metals (nickel plus vanadium) are an important factor since large amounts (over 150 ppm) will cause rapid deterioration of the catalyst. The free metals, or the sulfides, deposit on the surface of the catalyst and within the pores of the catalyst, thereby... 

Characterization of Feedstock and Catalysts. The elemental analysis and physical properties of various feedstocks used in this study are given in Table I. The data show that the virgin bitumen contains... 

As crudes become heavier with higher levels of sulfur and metals, it becomes more difficult to produce acceptable marketable coke quality while maximizing desirable liquid product yield. This mandates that refiners and designers scrutinize physical properties, upstream processing and downstream requirements when selecting a feedstock. 

The physical properties of a certain feedstock that determine the yields and product qualities include gravity, characterization factor, carbon residue, sulfur content and metals content. The last three properties are of specific importance. 

These feedstocks were tested in a number of carbon black furnace reactors employing different geometries and different operating conditions. The experiments were designed to develop data for correlation between feedstock composition, yield, production rate, and properties of carbon black produced. The physical properties of the carbon blacks were measured as were the properties of uncured rubber compounds and vulcanizates in standard test recipes. 

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