Components, feed

The hterature consists of patents, books, journals, and trade Hterature. The examples in patents may be especially valuable. The primary Hterature provides much catalyst performance data, but there is a lack of quantitative results characterizing the performance of industrial catalysts under industrially reaHstic conditions. Characterizations of industrial catalysts are often restricted to physical characterizations and perhaps activity measurements with pure component feeds, but it is extremely rare to find data characterizing long-term catalyst performance with impure, multicomponent industrial feedstocks. Catalyst regeneration procedures are scarcely reported. Those who have proprietary technology are normally reluctant to make it known. Readers should be critical in assessing published work that claims a relevance to technology. 

Often the catalysts described in the Hterature are not quite the same as those used in industrial processes, and often the reported performance is for pure single-component feeds. Sometimes the best quantitative approximations that can be made from the available Hterature are those based on reported kinetics of reactions with pure feeds and catalysts that are similar to but not the same as those used in practice. As a first approximation, one may use the pubHshed results and scale the activity on the basis of a few laboratory results obtained with reaHstic feeds and commercially available catalysts. 

The agitated flash dryer (Fig. 12-106) consists of four major components feed system, drying chamber, heater, and exhaust air system. 

Component Feed composition Distillation composition Bottoms composition ... 

Component Feed, moles Over- head, moles Bottoms, moles Equilibrium K s Top tray Reboiler ... 

Component Feed Mols/hr Overhead Mols/hr Bottoms Mols/hr... 

More recently, there have been attempts to study band patterns as they are affected by shock layers in nonlinear chromatography.42 Shock layers are steep boundaries that develop when the boundary front of an elution band becomes very steep and self-sharpening at high concentrations. While comparison of predicted and experimental data was promising, this study, like the others mentioned above, was done with single-component samples and awaits further analysis with the kinds of multi-component feeds more frequently encountered in process purifications. 

Component feed vapour air air feed outlet outlet gas acid air feed gas feed acid acid ... 

Component Feed Vapour Air Air Feed Outlet Outlet Gas Acid Air Feed Gas Feed Acid Acid... 

From the topographical viewpoint illustrated in Figure El4.6a the process comprises a set of reactor-separator sections that connect a set of component feeds (specified as source nodes) to component products (specified as destination nodes). Each section is a prescribed sequence of reactors and associated separation units, and sev-... 

Component Feed Product Bottoms Relative volatility... 

Component feed liquid gas feed liquid gas feed liquid gas... 

This example is taken from Floudas and Paules (1988) and consists of a three-component feed stream to be separated into pure component products. Two types of hot utilities are available along with one cold utility. The data for this example are shown in Table 9.1. 

The nonsharp separation superstructure for a four-component feed stream to be separated into two products Pi and P2 is shown in Figure 9.4. Since the feed stream consists of four components (i.e., A, B, C, D) then there are three separation breakpoints (i.e., AIBCD,AB/CD, and ABC ID) and hence we postulate in the superstructure shown in Figure 9.4 the following three separation tasks ... 

In Figure 9.4, letters within parentheses stand for the components that will be present if nonsharp separation takes place. For example, stream 7 will consist of component B only if the recovery of this component in column I is incomplete (which means that column I is a nonsharp separator. The bottom product of column I (stream 10) can, in principle, contain all four components. If the feed to column I, stream 6, contains all four components, then stream 10 would contain all four components for non-sharp separation and only B, C, and D for sharp separation. Sharp separation is taken to mean recoveries greater than 99%. If stream 6 consists of only A and B, then stream 10 would contain A and B or B only, depending on whether the separation is nonsharp or sharp. The operation of columns II and III can be described in a similar fashion. This shows that the superstructure consists of both options for each column - sharp or nonsharp separation. The main steps in the derivation of the superstructure for a four-component feed stream are as follows ... 

The example considered here is taken from Aggarwal and Floudas (1990) and consists of a three-component feed stream to be separated into two products, Pi and P2, which are also three-component streams. The data for this problem is shown in Table 9.2. Since the feed stream features three components, there are two separation breakpoints (i.e., A/BC and AB/C) and hence the superstructure has two columns. The nonsharp superstructure for this example is shown in Figure 9.5. Note that all streams are numbered so as to define the required variables which are... 

Equation (2.37) and the equivalent expression for component 7 give the water flux and the salt flux across the reverse osmosis membrane in terms of the pressure and concentration difference across the membrane. There is an analytical expression for Equation (2.37) for a two-component feed mixture that allows the performance of the membrane to be calculated for known permeabilities, DtK 11 and DjK /l, and feed concentrations, cio and cjo. However, more commonly... 

Component Feed, mol/h Overhead product, mol/h Bottoms product, mol/h... 

Membrane process Main components, feed Main components, permeate Relevance... 

Often model systems are used in mechanistic studies. Use of a single-component feed rather than a broad boiling range greatly simplifies analysis schemes. However, part-per-million quantities of impurities in real feedstocks can sometimes severely complicate catalyst usage, selectivity, and life. 

Component Feed Mole % distillate Bottoms Moles per 100 moles or Teed Distillate Bottoms ... 

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