Characterization gravity

It has also been proposed to classify heavy oils according to characterization gravity. This is defined as the arithmetic average of the instantaneous specific gravity of the distillates boiling at 177°C (350°F), 232°C (450°F), and 288°C (550°F) vapor line temperature at 25 mm pressure in a true boiling-point distillation. 

Numerous other constants are more limited in usefulness (see Table 4-1) as (1) aniline point (D611), (2) Parachor, which involves surface tension and gravity, (3) carbon-hydrogen ratio, (4) characterization gravity, which is used in judging stocks for thermal cracking, (5) Diesel ... 

In this manner, the KuQp of a petroieum cut can be calcuiated quickly from readily avkilable data, i. e., the specific gravity and the distillation curve. The A //np value is between 10 and 13 and defines the chemical nature of the cut as it will for the pure components. The characterization factor is extremely Va luable and widely used in refining although the discriminatory character of the Kuqp is less than that obtained by more modern physical methods described in 3.2 and 3.3. 

It is common that a mixture of hydrocarbons whose boiling points are far enough apart petroleum cut) is characterized by a distillation curve and an average standard specific gravity. It is then necessary to calculate the standard specific gravity of each fraction composing the cut by using the relation below [4.8] ... 

K y = Watson characterization factor 5 = standard specific gravity... 

The nature of these paraffins and their concentration in diesel fuel affect the three temperatures that characterize the cold behavior. The cloud point is the temperature at which crystals of paraffins appear when the temperature is lowered. The cold filter pluming point is defined as the temperature under which a suspension no ionger flows through a standard filter. Finally, the pour point is the temperature below which the diesel fuel no longer flows by simple gravity in a standard tube. These three temperatures are defined by regulations and the refiner has three types of additives to improve the quality of the diesel fuel of winter. 

Iodine vapor is characterized by the familiar violet color and by its unusually high specific gravity, approximately nine times that of air. The vapor is made up of diatomic molecules at low temperatures at moderately elevated temperatures, dissociation becomes appreciable. The concentration of monoatomic molecules, for example, is 1.4% at 600°C and 101.3 kPa (1 atm) total pressure. Iodine is fluorescent at low pressures and rotates the plane of polarized light when placed in a magnetic field. It is also thermoluminescent, emitting visible light when heated at 500°C or higher. 

Three frequently specified properties are density—specific gravity—API gravity, characterization factor, and sulfur content (2,6,7). The API (American Petroleum Institute) gravity is a measure of density or specific gravity (sp gr) ... 

Evidence of the appHcation of computers and expert systems to instmmental data interpretation is found in the new discipline of chemometrics (qv) where the relationship between data and information sought is explored as a problem of mathematics and statistics (7—10). One of the most useful insights provided by chemometrics is the realization that a cluster of measurements of quantities only remotely related to the actual information sought can be used in combination to determine the information desired by inference. Thus, for example, a combination of viscosity, boiling point, and specific gravity data can be used to a characterize the chemical composition of a mixture of solvents (11). The complexity of such a procedure is accommodated by performing a multivariate data analysis. 

The American Society for Testing and Materials (ASTM) and the American Oil Chemists Society (AOCS) provide standard methods for determining properties that are important in characterization of dimer acids. Characterization of dimer acids for acid and saponification values, unsaponiftables, and specific gravity are done by AOCS standard methods ... 

When simple Hquids 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... 

Mi ellaneous Characterizing Constants The radius of gyration (R) is a simultaneous size-shape fac tor varying with the manner in which mass is distributed about the center of gravity of the molecule. For planar molecules, the radius of gyration is... 

Parameters As a way of characterizing probabihty functions and densities, certain types of quantities called parameters can be defined. For example, the center or gravity of the distribution is defined to be the population mean, which is designated as [L. For the coin toss [L =. 5, which corresponds to the average value of x i.e., for half of the time X will take on a value 0 and for the other half a value 1. The average would be. 5. For the spinning wheel, the average value would also be. 5. 

The innovative features, such as passive, gravity-driven ECCS, simplified RCS, digital I C, optimized plant arrangement, and modular construction methods, characterize the AP600 design. These changes result in fewer systems, equipment, operations, inspections, maintenance, and QA requirements (Table 6.1-7). Features of the AP-6(K) are as follows ... 

Another relationship used to indicate the crude type is the Watson characterization factor. The factor also relates the mid-boiling point of the crude or a fraction to the specific gravity. 

The simple API gravity test provides valuable information about the quality of a feed. But the shift in API usually signals changes in other feed properties, such as carbon residue and aniline point. Addi tional tests are needed to fully characterize the feed. 

Most theoretical studies of heat or mass transfer in dispersions have been limited to studies of a single spherical bubble moving steadily under the influence of gravity in a clean system. It is clear, however, that swarms of suspended bubbles, usually entrained by turbulent eddies, have local relative velocities with respect to the continuous phase different from that derived for the case of a steady rise of a single bubble. This is mainly due to the fact that in an ensemble of bubbles the distributions of velocities, temperatures, and concentrations in the vicinity of one bubble are influenced by its neighbors. It is therefore logical to assume that in the case of dispersions the relative velocities and transfer rates depend on quantities characterizing an ensemble of bubbles. For the case of uniformly distributed bubbles, the dispersed-phase volume fraction O, particle-size distribution, and residence-time distribution are such quantities. 

Time scales of transport can also be applied to situations when no well-defined reservoirs can be defined. If the dominant transport process is advection by mean flow or sedimentation by gravity, the time scale characterizing the transport between two places is simply tadv = L/V where L is the distance and V the transport velocity. Given a t)q)ical wind speed of 20 m/s in the mid-latitude tropospheric westerlies, the time of transport around the globe would be about 2 weeks. 

Reactors with a packed bed of catalyst are identical to those for gas-liquid reactions filled with inert packing. Trickle-bed reactors are probably the most commonly used reactors with a fixed bed of catalyst. A draft-tube reactor (loop reactor) can contain a catalytic packing (see Fig. 5.4-9) inside the central tube. Stmctured catalysts similar to structural packings in distillation and absorption columns or in static mixers, which are characterized by a low pressure drop, can also be inserted into the draft tube. Recently, a monolithic reactor (Fig. 5.4-11) has been developed, which is an alternative to the trickle-bed reactor. The monolith catalyst has the shape of a block with straight narrow channels on the walls of which catalytic species are deposited. The already extremely low pressure drop by friction is compensated by gravity forces. Consequently, the pressure in the gas phase is constant over the whole height of the reactor. If needed, the gas can be recirculated internally without the necessity of using an external pump. 

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