Yield pattern

Yield Pattern. Table XI presents a feed/product summary for a naphtha based billion lb/yr ethylene plant at various severities of 23, 25, and 27 wt % ethylene (once-through basis). The naphtha feed is the same one as referred to earlier (see Table III). It is immediately apparent that feed requirements are increased at lower severities for a given ethylene production rate. Also, production of olefin by-products increases as severity decreases. Note especially the 36% increase in propylene production as severity is dropped from 27% ethylene to 23% ethylene. Butadiene production goes up somewhat, while butylenes production jumps by over 100% going from 27 to 23% ethylene. 

Table V. Hydrocracking Mid-Distillate COED Oil Yield Patterns (Wt % of Feed)...

The addition of a MaxEne process to the flow scheme provides several benefits, beginning with an increase in throughput of 18%. With this higher feed rate, the MaxEne extract stream matches the capacity of the cracker, 34.1 weight units. However, the MaxEne extract is a preferable feed for the cracker because of its high normal paraffin content. Consequently, the yield pattern from the cracker, in Table 4.12, is improved. Olefins increase by 15%, with ethylene increasing by almost 50%. In addition, LPG increases by 32%. 

Application Upgrade natural gas condensate and other contaminated streams to higher-value ethylene plant feedstocks. Mercury, arsenic and lead contamination in potential ethylene plant feedstocks precludes their use, despite attractive yield patterns. The contaminants poison catalysts, cause corrosion in equipment and have undesirable environmental implications. For example, mercury compounds poison hydrotreating catalysts and, if present in the steam-cracker feed, are distributed in the C2-C5+ cuts. A condensate containing mercury may have negative added-value as a gas field product. 

Recently, mass-dependent isotopic variation for molybdenum has surfaced as a tool of high paleo-environmental potential (Barling et al, 2001 Barling and Anbar, submitted). Specifically, relatively inefficient scavenging of molybdenum from seawater by oxide phases under oxic marine conditions—compared to efficient removal under anoxic settings—yields patterns of molybdenum isotope variabihty in seawater (recorded in the black shales) that may track the global proportion of oceanic anoxia over geological time. 

The yield-shift reactor overcomes some of the drawbacks of the other reactor models by allowing the designer to specify a yield pattern. Yield-shift reactors can be used when there is no model of the kinetics, but some laboratory or pilot plant data are available, from which a yield correlation can be established. 

An additional significant difference in the product distribution of MCM-41, Si-VPI-5 and the equilibrium catalyst was observed in the n-paraffin yield pattern (Figure 6). While the equilibrium catalyst produces predominantly C3 and C4 n-paraffms, the major product of Si-VPI-5 and especially of MCM-41 is propane. This result was intensified on a proton ion-exchanged sample of MCM-41 (called H-MCM-41), which additionally increases the activity of the MCM-41 catalyst from 47% before the exchange to about 60 %. 

Their stability in aromatization was also examined in the same way stated above. Zn-Al-silicate (C), having a smaller intensity of the TPD peak showed far greater stability than Zn-Al-silicate (A) as is shown in Fig. 4. The analysis of the amount of coke deposited on the catalyst showed 28 wt% for Zn-Al-silicate (A) after the experiment of 170 h and 44 wt% for Zn-Al-silicate (C) after 2000 h of experiment, indicating lower coke-forming rate of the latter catalyst. This indicates the importance of acid-property control in order to prepare the catalyst with a long-term stability. Typical yield pattern of Zn-Al-silicate (C) is also shown in Table 3. 

The second stage of development is typically aimed at mimicking commercial operations by employing recycle streams to achieve realistic simulations of the integrated process. Isothermal conditions are usually maintained in the reactor, but if heat release is a concern, such as residuum hydrotreating, then it is wise to run adiabatically so that the adiabatic reaction temperature can be established and also how much heat must be removed in the final commercial design. Defining catalyst deactivation, yield patterns, and how various feed types influence the process are typical aspects to explore. 

Fig. 3.7 Yield pattern for various reactor types, for the selective hydrogenation ofcyclododecatriene to the mono-olefin. (Adapted from Refs. [46, 47[.)...

For the polar fraction, the combined n-alkane + 1-alkene yield increased up to 60 min stress time, then reversed (Figure 4). The yield of the larger molecules - 15 carbons and above -was drastically reduced at 180 min. Even at 16 min the products obtained in largest yield were on the low end of the JP-5 distillation range. This was consistent with the lower value found by nmr for the average unbranched alkyl chain length. The aromatic yield pattern fell between that for the saturate and polar fractions. The maximum yield for the aromatic fraction always fell at 10 or 11 carbons with a fairly sharp maximum. 

In many cases it is necessary to synthesize porous materials in a well-defined preordered shape or within confined geometries, which introduces a pathway to fabricate hierarchically ordered porous materials. The techniques mentioned above have been shown to be capable of producing structured and well-ordered templates [61] within capillaries [50], thin plates [62], micromolds [63], or photoresist patterns [64,65]. Spatial adjustment of the surface functionality on the substrate and its wetting properties can yield patterned colloidal films [66,67]. Finally, confining the particle dispersion itself by printing techniques produces micropatterned arrays [68]. This was also shown to work without the necessity of preceding surface patterning steps [69]. 

Whereas the lift-off-based method can in principle yield patterns down to the tens of nanometers range, microcontact printing of initiators (Figure 3.IB) results in larger patterns in the micrometer range. A soft... 

Computer modelling has explored the yield pattern in the polymer matrix. The two-dimensional model in Fig. 4.13a has cylindrical rubber particles at random positions in a box, under tensile strain in the horizontal direction. The rubber particles are assumed to be pre-cavitated. Figure 4.13b shows contours of hydrostatic pressure, for an axisymmetric approximation of a BCC array of rubber spheres. Cavitation relieves high hydrostatic tensions at the pole of the rubber particles. Consequently, well bonded, pre-cavitated inclusions stabilise the matrix yielding. 

It is important at the outset to clearly define ones basic goals in the scientific study of living systems. Indeed, these objectives are often difficult to discern from research methodology textbooks. Simply put, this enterprise is primarily concerned with the detection of systematic relationships amidst the morass of variability in biobehavioral responses. This task calls for the partitioning of observed variability into systematic and random components, which in turn will yield patterns of associations such that events can be described, predicted, controlled, and ultimately understood. In the simplest case, a research question or hypothesis is tested by an investigation of the existence, direction, and magnitude of a relationship between an independent or predictor variable (IV) and a DV or criterion variable. 

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