Lump composition

Delumper Converts lumped composition into set of pseudocomponents based on true boiling point (TBP) suitable for fractionation Carries chemical information about the kinetic lumps as an attribute of the pseudocomponent Additional delumping of light gas into C1-C4 components using known kinetics [43]... 

We can obtain the lump composition of the feedstock directly via GC/MS, H NMR, NMR, HPLC and ASTM methods. However, this is infeasible on a regular basis for refineries, given the changing nature of the feedstock. Aspen HYSYS Petroleum Refining includes a method that uses existing feed analysis to infer feed composition using routinely collected data. However, we have developed an alternative scheme to infer feed composition. We detail this method in Section 4.8. 

Aspen HYSYS Petroleum Refining includes a method to convert limited feed information (distillation curve, density, viscosity, refractive index, etc.) into kinetic lumps for use in the unit-level FCC model. In this section, we present an alternative method based on data and methods available in the public literature. We extend the work by Bollas et al. [52] to infer the kinetic lump composition from limited process data. This method uses techniques to normalize the distillation curve, cut the distillation curve into boiling-point lumps, and infer the composition of the each of these boiling-point lumps. We have developed all of these techniques into spreadsheets using Microsoft Excel. These spreadsheets are available in the DVD accompanying this text... 

We can now use the two methods we have developed to propose a technique to use limited feed information to infer lumped composition. This technique is similar to the one given by Hollas et al. [52]. However, we make several changes to account for limited data sets. We outline the technique in the following steps (Changes from the procedure of Hollas et al. [52] are indicated with a ( ) ... 

We have found that this technique can provide reasonable estimates of kinetic lump composition. It is difficult to justify a more sophisticated scheme given the limited amount data available. Some refiners also make bulk chemical composition measurement of the feed which includes a measurement of the total aromatic content The sum of the aromatic kinetic lumps generated from the above technique generally agrees with the measured aromatic content... 

When we import the feed type, Aspen HYSYS shows the details of the feed type as shown in Figure 4.57. The Kinetic Lump Weight Percents indicate the starting composition of the kinetic lumps and the Methyls and Biases indicate how various bulk properties affect the final lump composition. Aspen HYSYS uses the biases to calculate actual kinetic lumps with the bias vectors. The bias vectors essentially correct the kinetic lump composition for the measured bulk properties (which we will enter) from the reference bulk properties in the feed type. We will not modify any information in this window and simply close it to continue the feed configuration process. 

Compute the bulk property information using the candidate lump compositions. 

Figure 5.14 shows the optimized distribution of PNA for this feed. As the distribution function predicts an A5 lump (a physically impossible solution), we ignore this component when calculating the lump composition. We note that each of the distributions has a different shape that reflects the different nature of a specific component class. If we use a simple normal distribution function, it is unlikely that we would be able to represent many different types of feed. 

Once we solve the model using the bulk property information, we can obtain the feed lump composition from the Feed Blend Section of the Results Tab as shown in Figure 5.70. The composition in mole fraction represents Aspen HYSYS best estimate of the composition from the bulk information and chosen feed Type. In our example, we also have the detailed compositional analysis by PNA and carbon number. We show these measured compositions in the Sample Data section of this chapter. 

Figure 5.73 Kinetic lump composition entry window.

Figure 5.72 shows the Feed Data Tab. We select Kinetic Lumps instead of Bulk Properties. Aspen HYSYS will now prompt to indicate that we have discarded the bulk property information. We confirm this change and edit the Kinetic lumps directly. We copy the results from Column U of the spreadsheet into the Edit Lumps dialog as shown in Figure 5.73. We enter the new feed lump composition by weight and normalize to make sure the sum of all the lump compositions is 1. The solver will automatically resolve the model using the new feed lump composition. In general, the initial residual should be on the order of le3 to le4, which indicates that only changes to the model are the feed lump compositions.

Figure 5.75 Enter lump composition (After normalization).

The difference between life cycle costs and the traditional accounting cost is that traditional costs are fairly easy to quantify, whereas life cycle costs are usually difficult to quantify and are usually either lumped iato general overhead costs or ignored altogether. They are very real, however, and when examined ia detail and fully quantified, the economics of composites allow them to displace the traditional materials. 

The Lurgi fixed-bed gasifier operates using lump coal of a noncaking type with an ash composition chosen to avoid a sticky, partly fused ash in the reactor. A slagging version of this gasifier has been tested in Westfield, Scotland. Other fixed-bed gasifiers have similar coal requirements. 

What we don t know is how the lumps of (Sn) and (Pb) are sized or shaped. And we can only find that out by cutting the alloy open and looking at it with a microscope." Now let s try a few other alloy compositions at 170°C. Using Figs 3.2(b) and 3.2(c) you should be able to convince yourself that the following equilibrium constitutions are consistent. 

Also in relumped form, single-event microkinetics account for all reactions at molecular level [2,3,13], This requires a molecular composition of the lumps considered. The definition of the lumps in hydrocracking is such that thermodynamic equilibrium can be assumed within the lumps. Per carbon number 12 lumps are considered, i.e., normal, mono-, di- and tribranched alkanes, mono-, di-, tri- and tetracycloalkanes and mono-, di-, tri- and tetra-aromatic components. 

When different portions of a mixture have different compositions, the mixture is said to be heterogeneous. For example, quartz is a pure chemical compound made from silicon and oxygen, and gold is a pure element, but the lump of quartz containing a vein of gold that appears in Figure 1-lla is a heterogeneous mixture because different parts of the lump have different compositions. 

Equilibrium data are thus necessary to estimate compositions of both extract and raffinate when the time of extraction is sufficiently long. Phase equilibria have been studied for many ternary systems and the data can be found in the open literature. However, the position of the envelope can be strongly affected by other components of the feed. Furthermore, the envelope line and the tie lines are a function of temperature. Therefore, they should be determined experimentally. The other shapes of the equilibrium line can be found in literature. Equilibria in multi-component mixtures cannot be presented in planar graphs. To deal with such systems lumping of consolutes has been done to describe the system as pseudo-ternary. This can, however, lead to considerable errors in the estimation of the composition of the phases. A more rigorous thermodynamic approach is needed to regress the experimental data on equilibria in these systems. 

If you mix sulfur and iron filings in a certain proportion and then heat the mixture, you can see a red glow spread through the mixture. After it cools, the black solid lump which has been produced, even if crushed into a powder, does not dissolve in carbon disulfide and is not attracted by a magnet. The material has a new set of properties it is a compound, called iron(II) sulfide. It has a definite composition, and if, for example, you had mixed more iron with the sulfur originally, some iron(II) sulfide and some leftover iron would have resulted. The extra iron would not have become part of the compound. 

Some samples may change on standing. For example, the cream separates out from milk samples and the buttery lumps have to be broken up before the analysis. The composition of other samples may change due to, for example, fermentation. 

Bloomery The earliest process for making iron from iron ore, operated from around 1500 BC until the blast furnace was invented around 1500 AD. The ore is heated with charcoal in a furnace blown by bellows the product, known as bloom, is a composite of iron particles and slag. When this is hammered, the slag is expelled to the surface and a lump of relatively pure iron remains. See also Catalan. 

When a very large number of reactants occurs, as in the treatment of petroleum fractions with a virtually continuous spectrum of boiling points, the problem is made more tractable by lumping the composition. The lumps are made up of pseudo components with limited boiling ranges and of partcular chemical types such as aromatics, paraffins, naphthenes, olefins and so on. 

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