Fractional consumption

Material costs are conveniently presented in tables that give the following name of material, form and grade, method of dehveiy, unit of measure, cost per unit, source of cost, annual consumption, annual cost, fractional consumption per unit of production, and cost per unit of production. 

The data demand the conclusion that reduction of Fe(Cp2+)surf, can become limited partially by mass transport and partially by ket at some point in the reaction (large fractional consumption of (FeCp2+)surf.) in the dark. This seems reasonable in view of the expected rate law, equation (8), the declining (FeCp2+) surf.] and a constant mass transport rate of fresh solution reductant. 

While the individual reaction rates are the variables that, can be affected in a reacting system, we often express the performance of the reactor in terms of measures derived from the rates. Conversion and yield are such quantities. Conversion refers to the fractional consumption of a reactant in the reactor feed, whereas yield refers to the amount of product made relative to the amount of a key reactant fed to the reactor. In recycle systems the per-pass conversion of the various reactants is a relevant measure. It depends upon the rate of reaction for the specific component but also on the reactor feed. The per-pass conversion of an excess reactant is less than that of a limiting reactant. For example, the per-pass conversion of ethylene in a typical vinyl acetate reactor is only 7 percent whereas the per-pass conversion of oxygen is 36 percent. In Chap. 2 we discussed the plantwide control implications of incomplete conversion. 

Figure 11. Effect of initial epoxy amine stoichiometries on the fractional consumption of epoxy (O) 1.0 1.0, epoxy amine 1.0 2.0, epoxy amine 1.0 3.0,...

Two moles of HCOj are obtained per mole of CO2 absorbed. Depending upon the conditions, all or some of the CO3 Introduced into the system may have reacted. In the amine absorption example, we observed how a chemical reaction increased CO2 absorption. Here we study how much of the chemical absorbent is being utilized in the reactive absorption the fractional consumption f of the chemical absorbent has been defined as the degree of saturation (Astarita et al., 1983). 

Develop a relation between the equilibrium partial pressure of H2S in the gas phase, PhzS> be fractional consumption/of a base B which absorbs H2S in an aqueous solution by the reaction (5.2.21). You are given that Cg is the total molar base concentration to start with is the equilibrium constant for the given reaction in terms of molar concentrations 5 is Henry s law constant for H2S in the solution. 

This is the equation for the operating line, providing a linear relationship between the ordinate jCAg/(l-XAg) and the abscissa /, representing the relation between the fractional consumption of the chemical absorbent C and the gas phase of species A at any location z in the column. This line has been plotted in Figure 8.1.17(a) along with the equilibrium curve (8.1.120) represented as... 

Neither of the above schemes for forming the nitric acidium ion involves water. However, the addition of moderate quantities of water depresses the zeroth-order rate by up to a factor of four, without disturbing the kinetic form. This last fact shows that an inappreciable fraction of the nitronium ions is reacting with water, and therefore to explain the results it is necessary to postulate the existence of a means, involving water, for the consumption of nitric acidium ions ... 

Ordinarily based upon total population, not just adults. A small fraction of the population usually accounts for a major portion of the consumption. ... 

The total world consumption of energy in all forms is only about 300 EJ (300 quads) thus the earth s heat has the potential to supply all energy needs for the foreseeable future (5). Economic considerations, however, may preclude the utilisation of all but a small part of this potential resource. Only a miniscule fraction of this energy supply has been tapped. 

Lubricants. Petroleum lubricants continue to be the mainstay for automotive, industrial, and process lubricants. Synthetic oils are used extensively in industry and for jet engines they, of course, are made from hydrocarbons. Since the viscosity index (a measure of the viscosity behavior of a lubricant with change in temperature) of lube oil fractions from different cmdes may vary from +140 to as low as —300, additional refining steps are needed. To improve the viscosity index (VI), lube oil fractions are subjected to solvent extraction, solvent dewaxing, solvent deasphalting, and hydrogenation. Furthermore, automotive lube oils typically contain about 12—14% additives. These additives maybe oxidation inhibitors to prevent formation of gum and varnish, corrosion inhibitors, or detergent dispersants, and viscosity index improvers. The United States consumption of lubricants is shown in Table 7. 

Mud lubricants and spotting fluids, although not needed for every well, are essential for many deep directional wells. The consumption of these materials is difficult to estimate, and represents a relatively small fraction of the total drilling fluid additive market. 

The HF concentration of the acid catalyst is maintained ia the range of 85—95% by regeneration within the unit s fractionation faciUties. A separate acid regeneration column (not shown ia Figure 2) is also iacluded to provide a means to remove excess acid-soluble oils and water. The regeneration of acid ia the unit accounts for the low consumption of fresh acid by the HF process. 

Table 1 shows the average percentages of scrap and pig iron used in the metallic charges for each of the three principal furnace types. DRI consumption averaged about 2% in electric furnaces and only a fraction of 1% in BOFs and cupolas. These percentages do not include the scrap consumed in blast furnaces and certain other special furnaces which amounted to 1.9 million t in 1994. DRI consumption in blast furnaces totaled 490,000 t in 1994. 

Instant tea is manufactured in the United States, Japan, Kenya, Chile, Sri Lanka, India, and China. Production and consumption in the United States is greater than in the rest of the world. World production capacity of instant teas depends on market demand but is in the range of 8,000 to 11,000 t/yr (3). The basic process for manufacture of instant tea as a soluble powder from dry tea leaf includes extraction, concentration, and drying. In practice, the process is considerably more compHcated because of the need to preserve the volatile aroma fraction, and produce a product which provides color yet is soluble in cold water, all of which are attributes important to iced tea products (88). 

The U.S. titanium market distribution is shown in Table 18. Before 1970, more than 90% of the titanium produced was used for aerospace, which feU to ca 70—80% by 1982. Mihtary use has continually decreased from nearly 100% in the early 1950s to 20% in the 1990s. In contrast to the United States, aerospace uses in Western Europe and Japan account for only 40—50% of the demand (58). The CIS s consumption of titanium metal prior to the breakup was about one-half of the world consumption. In the 1980s, considerable amounts were used for submarine constmction. Since the breakup of the former Soviet Union, the internal consumption of titanium in the CIS is beheved to be a modest fraction of its former capacity, thus leaving a large capacity available for export. The world production faciUties for titanium metal and extraction are given in Table 19. 

So, Sulfolane and Carom, ca 1997, are two current rival processes. Sulfolane has a slight advantage over Carom ia energy consumption, while Carom has 6—8% less capital for the same capacity Sulfolane unit. In 1995, Exxon (37) commercialized the most recent technology for aromatics recovery when it used copolymer hoUow-fiber membrane ia concentration-driven processes, pervaporation and perstraction, for aromatic—paraffin separation. Once the non aromatic paraffins and cycloparaffins are removed, fractionation to separate the C to C aromatics is relatively simple. 

Polymers account for about 3—4% of the total butylene consumption and about 30% of nonfuels use. Homopolymerization of butylene isomers is relatively unimportant commercially. Only stereoregular poly(l-butene) [9003-29-6] and a small volume of polyisobutylene [25038-49-7] are produced in this manner. High molecular weight polyisobutylenes have found limited use because they cannot be vulcanized. To overcome this deficiency a butyl mbber copolymer of isobutylene with isoprene has been developed. Low molecular weight viscous Hquid polymers of isobutylene are not manufactured because of the high price of purified isobutylene. Copolymerization from relatively inexpensive refinery butane—butylene fractions containing all the butylene isomers yields a range of viscous polymers that satisfy most commercial needs (see Olefin polymers Elastomers, synthetic-butylrubber). 

The annual production of diamond by this process is only a small fraction of total industrial diamond consumption. 

Polychloroprene consumption woddwide, except for eastern European countries and China, has plateaued at about 250,000 metric tons per year with some continued slow growth expected. Annual production averaged 307,000 metric tons during the 1980s with at least part of the difference being exported to formerly SociaUst countries. Production in Armenia has been limited to a fraction of its capacity of 60 metric tons by environmental problems and, in fact, is currendy shut down. The People s RepubHc of China has three plants with a combined capacity of 20 metric tons (2). 

In concentrated electrolytes the electric current appHed to a stack is limited by economic considerations, the higher the current I the greater the power consumption W in accordance with the equation W = P where is the electrical resistance of the stack. In relatively dilute electrolytes the electric current that can be appHed is limited by the abflity of ions to diffuse to the membranes. This is illustrated in Eigure 4 for the case of an AX membrane. When a direct current is passed, a fraction (t 0.85-0.95) is carried by anions passing out of the membrane—solution interface region and... 

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