Feedstock selection

Cmde selection is extremely important for the profitable production of lubes. Only a limited number of crudes contain a sufficient quantity of lubes quality molecules. Downstream unit operability is affected by crude selection, as are rates and yields. Typically, manufacturers would prefer operating at maximum throughput, thereby spreading costs over a larger volume. Poor crude selection can result in downstream bottlenecks reducing overall throughput. 

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Olefin Feedstock Selection. The selection of feedstock and severity of the cracking process are economic choices, given that the specific plant has flexibiUty to accommodate alternative feedstocks. The feedstock prices are driven primarily by energy markets and secondarily by supply and demand conditions ia the olefins feedstock markets. The prices of iadividual feedstocks vary widely from time to time as shown ia Figure 2, which presents quarterly prices of the various feedstocks ia the United States from 1978 through 1991 ia dollars per metric ton (1000 kg) (4). 

Both processes have advantages and disadvantages. Currently, they have about an equal share of the global market. The initial investment cost in the irradiation equipment is high, but it is considerably more productive than chemical cross-linking, having the additional advantage of uniform product quality and flexibility of feedstock selection. The product from radiation cross-linked polyolefins is thin, with fine cells and smooth white surfaces. The comparison of chemical and radiation processes is in Table 8.8. ... 

Perhaps the most important of these factors involves the raw material employed for this purpose and the by-product volumes and prices. In this connection we discuss the product distributions from potential various feedstocks and current trends in feedstock selection, illustrating the significant role feedstocks play in the ethylene commercial picture. In addition, the effects on production economics of the factors of plant size and severity of operation are investigated. 

The light hydrocarbons produce only minor amounts of by-products, while naphtha and heavier feeds produce substantial quantities of propylene, butadiene, and aromatics. Thus, while in the United States these products are obtained generally from other routes at present, in Europe and Japan ethylene production serves as a major source of these chemicals. As discussed in greater detail later, by-product outlet considerations can play an important role in feedstock selection, and by-product realizations can have a major effect on the ethylene production economics. 

In view of the predicted tight worldwide propylene supply/demand situation (3) the yield of propylene as well as that of ethylene will be an important consideration in feedstock selection. 

The feedstock selected as the most applicable for the pilot facility was pelletized MSW. The pellets, obtained from the Teledyne National Company, had been preprocessed to remove metal and most of the moisture before pelletizing. A representative analysis based on an average of several analyses is presented in Tables I and II. The pellets were preferred over shredded MSW due to the relative ease of handling in the 10 cm diameter screw feeder used in the pilot facility. A larger combustor system would not be limited to the use of a pelletized feed. 

Coal substances have complex chemical structures and their compositions are highly variable. For example a carbon/hydrogcn composition in bituminous coal may be represented as about one atom of hydrogen per atom of carbon. For a generic gasification process based on the above coal feedstock, selected as reference carbonaceous fuel, the following (not balanced) overall chemical equation can be written as ... 

Kellogg Brown Root LLC Ethylene, SUPERELEX Hydrocarbon feedstock Selective Cracking Optimum Recovery (SCORE) pyrolysis furnace cracks the feed hydrocarbon in the presence of dilution steam into large amounts of ethylene, propylene and byproducts. Furnace effluent is cooled by generating steam and quenched further to remove heavy gasoline, fuel oil and dilution steam 172 NA... 

In the wider context of conceptual process design, sustainability issues like feedstock selection, (re-)use of catalyst and (re-)use of solvents are of key importance. In our perspective of life span (c/. explanatory caveat in section 1.4), we do not cover those aspects as we focus exclusively on the minimization of loss of resources in the operational phase. 

With LCA the feedstock selection for defined products and the decision of how to produce the feedstock and the product are set on a factual basis. 

Today s refineries often have multiple sources of feed. Feed optimization is typically done using linear programming, where models are used to determine feedstock selection based upon the greatest economic benefit. 

Feedstock selection largely dictates the reactions and conditions that are employed in a chemical synthesis and is, therefore, of utmost importance in the practice of green chemistry. A feedstock should be as safe as possible. The source of a feedstock can largely determine its environmental impact, and the acquisition of the feedstock should not strain Earth s resources. The process of isolating and concentrating a feedstock can add to the potential harm of otherwise safe materials. This is true of some metal ores in which corrosive and toxic reagents (in the case of gold, e.g., cyanide see Section 16.4) are used to isolate the desired material. 

Methanol production economics highly depend on the feedstock selection and feedstock prices. Methanol can be manufactured from any hydrocarbon source naphtha, oil, coal, wood, biomass, LPG, etc. The naphtha, fraction of crude oil... 

The feedstock selection will be the most important challenge for three reasons ... 

Conventionally, woody trees were broadly classified as softwood or gymnosperm and hardwood or angiosperm. Hardwood comes from angiosperms, such as oak, eucalyptus, and alder, which are dicots (Octave and Thomas, 2009). Softwood usually comes from evergreen conifer trees like pine or spruce. Other classifications of forest-based plants are broad-leaved trees and pine-leaved trees. Almost 46% of biorefinery prefers raw materials from conifer species, mainly spruce, pine, etc., and 31% of broad-leaves such as eucalyptus. Mostly stem wood is preferred as a suitable feedstock for the biorefinery process. Approximately 8% of the known biorefinery processes utilize all parts of the tree (Fitzpatrick et al., 2010). Thus the consensus in the biorefinery industry is that the feedstock selection should be based on the main constituents of the wood (cellulose, hemicellulose, and lignin) and not on specific chemicals (glucose, xylose, etc.) generally considered in conventional fermentation processes. 

This is referred to as N+A or N+2A indicator for the feed. Many correlations for reformer yield exist on the basis of these indicators. However, Little [6] indicates that these correlations often have included strong assumptions such as catalyst type and operating conditions. While it may serve for simple feedstock selection, it is not the only significant indicator of unit performance. 

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