Feedstock availability

Simple conventional refining is based essentially on atmospheric distillation. The residue from the distillation constitutes heavy fuel, the quantity and qualities of which are mainly determined by the crude feedstock available without many ways to improve it. Manufacture of products like asphalt and lubricant bases requires supplementary operations, in particular separation operations and is possible only with a relatively narrow selection of crudes (crudes for lube oils, crudes for asphalts). The distillates are not normally directly usable processing must be done to improve them, either mild treatment such as hydrodesulfurization of middle distillates at low pressure, or deep treatment usually with partial conversion such as catalytic reforming. The conventional refinery thereby has rather limited flexibility and makes products the quality of which is closely linked to the nature of the crude oil used. 

ElexibiHty allows the operator to pick and choose the most attractive feedstock available at a given point in time. The steam-cracking process produces not only ethylene, but other products as weU, such as propylene, butadiene, butylenes (a mixture of monounsaturated C-4 hydrocarbons), aromatics, etc. With ethane feedstock, only minimal quantities of other products ate produced. As the feedstocks become heavier (ie, as measured by higher molecular weights and boiling points), increasing quantities of other products are produced. The values of these other coproduced products affect the economic attractiveness and hence the choice of feedstock. 

Fatty acid methyl esters (FAME) are currently manufactured mainly by trans-esterification with an alcohol, using a homogeneous base catalyst (NaOH/KOH). Methanol is more suitable for biodiesel manufacturing, but other alcohols can in principle also be used, depending on the feedstock available. The... 

Project economics, feedstock availability, regulation, and product integration... 

The focus in this chapter is on CO2 reduction and feedstock availability, rather than on fuel quality and composition and related local emissions. 

Fuel Feedstock availability Supply security/ supply potential Handling Volumetric energy density... 

Feedstock availability, or what alternatives exist to nonrenewable fossil feedstock. 

There are four alternative fuels that can be relatively easily used in conventional compression ignition (Cl) engines vegetable oil, biodiesel, Fischer-Tropsch (FT), and dimethyl ether (DME). Both FT and DME can be manufactured from natural gas and are therefore not limited by feedstock availability. Biodiesel on the other hand, is produced from vegetable (and some waste animal) oils whose supply for non-nutritional uses is presently quite limited. 

From the refinery side, the proposed model will provide the optimal network integration between the refineries, process expansion requirements, operating policy based on different feedstock combination alternatives, process levels and operating modes. On the petrochemical side, the model will establish the design of an optimal petrochemical process network for the production of PVC from the range of process technologies and feedstocks available to satisfy a given demand. 

The mechanism for bacterial synthesis of PHA is not the simple dehydration reaction between alcohol and carboxyl groups. It is more complicated and involves the coenzyme A thioester derivative of the hydroxyalkanoic acid monomer (produced from the organic feedstock available to the bacteria) [Kamachi et al., 2001], Growth involves an acyl transfer reaction catalyzed by the enzyme PHA synthase (also called a polymerase) [Blei and Odian,... 

Improvements in feed preparation and pretreatment have made important contributions to the advances in alkylation technology (12, 17). The ability to design better fractionators has made higher quality feedstocks available, and feed pretreatment facilities have been developed to remove water, mercaptans, sulfides, and diolefins effectively. The benefits of these advances have been realized as higher alkylate yields and octanes, lower acid consumption, and reduced corrosion. 

Earlier we showed that variations in the prices for feedstocks could have an important influence in determining the best ethylene route. Now we quantify these effects and tie this into current trends regarding feedstock availabilities which would influence the question. 

Synthesis-Gas-Production Processes. These processes were improved and developed as a result of changes in feedstock availability and economics. Before World War II, most NH3 plants obtained H2 by reacting coal or coke with steam in the water-gas process, A small number of plants... 

There seems to be little direction in terms of stability of supply or any measure of self-sufficiency in liquid fuels precursors, other than resorting to military action. This is particularly important for the United States refineries since a disruption in supply could cause major shortfalls in feedstock availability. 

Feedstock Feedstock requirement (t/yr) Feedstock available (t/yr) Proportion of supply (%) Ethanol (gal/t)... 

Bioremediation processes constitute a class by itself, which can often be cost-effective. The primary advantage of bioremediation is that it can be used in situ. The negatives of the process are that it is time-consuming and is very sensitive to the feedstock available, temperature, and moisture. Bioremediation works well for materials such as explosives, but is ineffective for materials like PCBs, particularly more highly chlorinated PCBs. Bioremediation, when performed in situ, may work well in one region of the strata but completely fail a short distance away. 

Clearly, the number of chemicals produced from coal-derived synthesis gas can expand as new technologies are developed and favorable economics exist. The most likely such chemicals are those for which processes have been demonstrated but which presently are uneconomic. Relatively small improvements in technology, shifts in feedstock availability and/or... 

The activation of C-H bonds for direct C C bond formation reactions has the potential to become very important especially if it can be accomplished for sp C-H bonds, in methane or alkanes as these are the major feedstocks available. In addition, C-H bond activation of functionalized organic compounds for selective C-C bond formation has been and will continue to be a very important goal of organometallic catalysis. So far the use of transition metal complexes has led to interesting results which however are not yet industrially relevant. 

Looking ahead, the future of large scale cross metathesis will be dictated by feedstock availability and market pulls. Additional sources of Fischer-Tropsch-derived olefins may be available from future gas-to-liquids (GTL) and... 

As a rule, the operating conditions must be adapted to the type of feedstock available and the desired product Table 1.8 gives the results of various primary steam reforming operations in different conditions of feed, temperature, pressure, quantity of water etc... 

In prindpie, phj-sical absorption is inapplicable to feedstocks available at very low pressures, because the amount of gas absorbed is proportional to the partial pressure of the gas. For the same reason, it is also necessary for the concentration of the component to be separated to be lugh, to make the operation ccononiically interesting. These operating conditions constitute a decisive vantage due to the reduction in the rate of solvent, and hence of its recirculation, and accordingly of capital investment and operating costs. 

Reaction-equilibrium calculations may be useful for estimation of the compositions of hydrocarbon feedstocks. A particular feedstock, available as a low-pressure gas at 500 K, is identified as "aromatic C8. ft could in principle contain the CgHio isomers o-xylene (OX), nr-xylene (MX), p-xylene (PX), and ethylbenzene (EB). Estimate how nrueh of each species is present, assuming the gas mixture has come to equilibrium at 500 K and low pressure. The following is a set of indepeirdent reactions (why ) ... 

Table VI shows a hydrocarbon material balance for operation of a neohexane unit. This operation is typical in that pentane and hexane are isomerized together and the recycle ratio is set by the amount of feedstock available and the capacity of the equipment.

---