Liquid feeds, characterization

X = Feed characterization factor X2 = Liquid volume percent conversion X3 = Feed API X4 = Feed sulfur content... 

For some liquid feedstocks such as naphthas, the componential composition is often obtained by gas chromatography (GC) and/or mass spectrometry (MS). For gas oils or heavier feedstocks, it is impossible to obtain the desired analysis. Paraffins, olefins, naphthenes, aromatics (PONA) grouping is sometimes used as a means of feed characterization. For gas oils. Bureau of Mines Correlation Index (BMCI) has been used as a parameter for feed characterization. Since the 1980s, nuclear magnetic resonance (NMR) spectroscopy has been used to characterize heavy feedstocks. 

Often, the process is characterized by conversion of a liquid feed (solution, suspension, or melt) into a granular product whereby the liquid is sprayed on or into a fluidized layer of primary particles. Sometimes the liquid is only a binder and, therefore, is introduced in small amounts together with or without finely divided solids. While in the first case growth occurs chiefly by layering, random agglomeration by coalescence prevails in the second. 

A unit operation is any single step in an overall process that can be isolated and that also tends to appear frequently in other processes. For example, a car s carburetor is a single unit operation of the engine, just as the heart is a unit operation of the human body. The concept of a unit operation is based on the idea that general analysis will be the same for all systems because individual operations have common techniques and are based on the same scientific principles. In separations, a unit operation is any process that uses the same separation mechanism. For example, adsorption is a technique in which a solid sorbent material removes speciflc components, called solutes, from either gas- or liquid-feed streams because the solute has a higher affinity for the solid sorbent than it does for the fluid. The mathematical characterization of any adsorption column is the same regardless... 

Azurdia JA, Marchal J, Laine RM. Synthesis and characterization of mixed-metal oxide nanopowder along the CoO t-Al203 tie line using liquid feed flame spray pyrolysis. J Am Ceram Soc 2006 89(9) 2749-56. 

For the liquid feed, two different feed lines were applied. The primary feed line was used to introduce a steady liquid feed to the column while the secondary feed line provided an additional liquid feed for a certain time interval. In this manner a square-wave cycled liquid feed was achieved. The cycled Uquid feed is characterized by four parameters, schematically shown in Fig. 1. A magnetic valve in the secondary feed line activated by an electronic timer was used to regulate the feed times of respectively the high and low liquid feeds. High and low liquid feed rates were controlled by calibrated rotameters. 

Solvent power characterizes the miscibility of solute and solvent. This concept covers two types of uses dissolving a solid or reducing the viscosity of a liquid. The solvent power should be as high as possible. However, a solvent used as an extractant should also be selective, i.e., extract certain substances preferentially from the feed being treated. 

Considering that the separation system is fully characterized, i.e., adsorbent and mobile phases, column dimensions, SMB configuration and feed concentration, the optimization of the TMB operating conditions consists in setting the liquid flow rates in each section and also the solid flow rate. The resulting optimization problem with five variables will be certainly tedious and difficult to implement. Fortunately, the... 

Products from coking processes vary considerably with feed type and process conditions. These products are hydrocarbon gases, cracked naphtha, middle distillates, and coke. The gas and liquid products are characterized by a high percentage of unsaturation. Hydrotreatment is usually required to saturate olefinic compounds and to desulfurize products from coking units. 

Adsorption chromatography relies on the different affinity of components of a mixture for a liquid moving phase and a solid stationary phase. The separation mechanism depends upon differences in polarity between the different feed components. The more polar a molecule, the more strongly it will be adsorbed by a polar stationary phase (Varki et al. 1999). Similarly, the more nonpolar a molecule, the more strongly it will be adsorbed by nonpolar stationary phase. It is often employed for relatively nonpolar, hydrophobic materials so that the solvent tends to be nonpolar while the stationary phase is polar. Proteins have a high affinity to polar chromatographic media and the recovery of the sample is usually difficult. Therefore, this method is not commonly used to purify and characterize proteins. 

When simple liquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

Homogeneous catalysts are structurally well-defined complexes and because they are soluble in the reaction mix are not subject to pore diffusion limitations as are heterogeneous catalytic materials. They are almost always highly selective towards desired products. The main consideration is that the complex be stable and reactor conditions chosen such that all the gaseous reactants are adequately dissolved and mixed in the liquid phase. Homogeneous catalysts are easily characterized by standard instrumental methods for compound identification such as XRD or spectroscopy. Deactivation is associated with attack by traces of carboxylic acidic byproducts and impurities in the feed such as 02 and chlorides that attack the ligand groups. 

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