Aspen distribution

The optimization of empirical correlations developed from the ASPEN-PLUS model yielded operating conditions which reduced the steam-to-slurry ratio by 33%, increased throughput by 20% while maintaining the solvent residual at the desired level. While very successful in this industrial application the approach is not without shortcomings. The main disadvantage is the inherent assumption that the data are normally distributed, which may or may not be valid. However, previous experience had shown the efficacy of the assumption in other similar situations. 

Bardet, M. Robert, D. Lundquist, K. von Unge, S. Distribution of erythro and threo forms of different types of P-O-4 structures in aspen lignin by carbon-13 NMR using the 2D inadequate experiment. Magn. Reson. Chem. 1998, 36, 597-600. 

As one can see from distribution of Cd concentration values in deciduous trees, there are three separate sections in this line. The first one amalgamates most wood samples, excepting Aspen tree samples. The second and third parts of the distribution line consist mostly the Aspen tree samples taken from two different... 

The Aspen Properties implementation of the NRLT-SAC method is available as a template. aprbkp file to license holders of Aspen Properties or Aspen Plus release 12.1 or above, by contacting Aspen s support centre or regional sales offices. The template is distributed with an Excel interface to simplify the data regression process and is suitable for non-expert users of Aspen Properties. Numerous Excel templates are available for data analysis and design calculations, based on the NRTL-SAC model. 

Design of extraction processes and equipment is based on mass transfer and thermodynamic data. Among such thermodynamic data, phase equilibrium data for mixtures, that is, the distribution of components between different phases, are among the most important. Equations for the calculations of phase equilibria can be used in process simulation programs like PROCESS and ASPEN. 

Molecular Weight Distribution of Aspen Lignins Estimated by Universal Calibration... 

This study describes the application of differential vis-cometry as a GPC detector to the problem of determining molecular weight distributions of acetylated hardwood lignins in tetrahydrofuran. Molecular weight distributions of ball-milled, organosolv, alkali-extracted/mild acid hydrolyzed, and alkali-extracted/steam exploded aspen lignins were estimated using universal calibration. 

Figure 5. Composite MWD diagram showing the calculated distributions of four of the five master fractions obtained from preparative chromatography of organosolv aspen lignin (fraction number 4 to 1 from left to right). The Mw values for the master fractions from left to right are 1,110, 1,310, 2,420, and 8,050, respectively. The insert shows the elution profile of organosolv aspen lignin from the YMC preparative /z-Styragel column (5 x 200 cm). The 30 fractions collected were pooled into the five master fractions shown.

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Abstract In this paper, we discuss the results of a preliminary systematic process simulation study the effect of operating parameters on the product distribution and conversion efficiency of hydrocarbon fuels in a reforming reactor. The ASPEN One HYSYS-2004 simulation software has been utilized for the simulations and calculations of the fuel-processing reactions. It is desired to produce hydrogen rich reformed gas with as low as possible carbon monoxide (CO) formation, which requires different combinations of reformer, steam to carbon and oxygen to carbon ratios. Fuel properties only slightly affect the general trends. 

All ASPEN models allow solids to be in inlet streams. The user does not need to take special precautions. The solids are normally assumed to be non-distributing in the liquid and vapor phases. That is, the phase equilibria is unaffected by the solid phase. However, the system does allow for the case of solids distributing into other phases. Solids are taken into account in the energy balance around each equipment model. 

Because ASPEN is to be used with coal conversion processes, its streams can be designated to carry an arbitrary number of solids or solid phases. This is done by specifying any number of substreams. In fact, the conventional vapor/liquid stream is normally assumed as a substream and solids can comprise other substreams. For the conventional vapor/liquid substream, process data is carried on component molar flows, total molar flow, temperature pressure, specific enthalpy, specific entropy, density, molar vapor fraction, molar liquid fraction, and molecular weight. For solid substreams, which are called "non-conventional substreams," the characterizing data is not as deterministic. The information associated with these substreams is called "attributes". Such attributes may be particle size distribution, ultimate and proximate analyses, or other material specific information. Another type of substream is an "informa-... 

In summary, ASPEN has many features, discussed earlier in this paper, which qualify it as a third generation process simulator. A flexible executive system allows the user to have unlimited numbers of dimensions in streams, components, models and stages in equipment models. Solids may be handled in as many phases as desired. Arbitrary properties, called attributes, may be given to these phases and streams to allow handling properties such as particle size distributions. An engineer... 

We acknowledge fruitful discussions with J. Heveling and R.D. Forrester. Thanks are given to S. Kauchali, University of the Witwatersrand, for assistance with the calculations of the equilibrium distributions within the C6= isomers using ASPEN procedures. 

Himmel ME, Tatsumoto K, Oh KK, Grohmann KG, Johnson DK, Chum HL (1989) Molecular weight distribution of aspen lignins estimated by universal calibration In Glasser WG, Sarkanen S (eds) Lignin, properties and materials ACS Symp Ser Vol 397, American Chemical Society, Washington, DC, 82-99... 

Many solids-handling operations have an effect on the particle size distribution (PSD) of the solid phase. The particle size distribution can also be an important product property. Aspen Plus allows the user to enter a particle size distribution as an attribute of a solid substream. In UniSim Design, the particle size distribution is entered on the PSD Property tab, which appears under worksheet on the stream editor window for any stream that contains a pure or hypothetical solid component. Unit operations such as yield-shift reactor, crusher, screen, cyclone, electrostatic precipitator, and crystallizer can then be set up to modify the particle size distribution, typically by using a conversion function or a particle capture efficiency in each size range. 

Because phenol will be relatively dilute in both the raffinate and extract phases, appropriate liquid-liquid K values for distribution of water and MIBK between phases at 105 C can be estimated from water-MIBK liquid-liquid equilibrium data [Rehak et al.. Collect. Czech Chem. Commun., 65, pp. 1471-1486 (2000)] to yield Kwaur = 0.0532 and K mibk = 53.8 (mass fraction basis). It is important in Aspen Plus to specify K values for all the components inthe extractor in order to properly model the liquid-liquid equilibria with this approach. 

Figure 7.4. Time-of-flight secondary-ion mass spectroscopy (ToF-SIMS) image of the distribution of Fe on a cross section of a trembling aspen (Populus tremuloi desMmchx ) root embedded in clayey soil material. The Fe values are normalized to the total ion yield of the surface. The bar is 100 (im. (From Martin et al., 2004.)...

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