Aspen Split

Aspen Split , Aspen Technology Inc., Cambridge/MA, USA, release 12... 

Aspen Split conceptual design of azeotropic systems Aspen Water minimize water usage... 

Aspen Split synthesis and design of non-ideal separation systems. 

Hence, the BV method can be used for the design of the distillation columns dealing with the separation of non-ideal mixtures. The method is implemented in some software, as Aspen Split (AspenTech) and Distil (Hyprotech). 

Aspen Engineering Suite 11.1 (includes ASPEN PLUS, ASPEN DYNAMICS, ASPEN PINCH, ASPEN SPLIT, BATCH PLUS, etc.) and HYSYS.Plant... 

To generate ternary plots and to use them for design. Aspen Split is used. This software is imbedded in Aspen Plus and can be accessed by going to the toolbar and clicking Library and References. The window shown in Figure 8.11 opens in which the Aspen Split box should be checked. A new page tab will appear at the bottom of the process flow diagram next to those of the standard unit operation models, which is shown in... 

Aspen Technology, Inc. Aspen Plus, Aspen Custom Modeler, Dynaplus, Split, Advent, Adsim. Cambridge, MA (1998). 

The next action is to estimate the separation targets and allocate the components in products. For the assessment of a separation a good practice is by setting up a recovery matrix as shown in Table 3.6. This expresses the split of a component between feed and products. Note that this information is available in Aspen Plus when simulating separators. 

An interesting aspect is the relation between the design of units and the quality specifications. The path of each impurity can be traced by paying attention to generation, exit points and accumulation in recycles. In this respect the component split matrix available in Aspen Plus [23] gives very useful information and is highly recommended. 

The simulation of a multi-component system was done with the flow sheeting program Aspen+. An external routine replaced the internal Kj-calculation with a fit function through the experimental Revalues as given in figure 4. The multistage column was split into a cascade of flash modules. Each module is connected to two other... 

The next simulation is for the same column, but using the RadFrac block in Aspen Plus. The feed is the same, the pressure is 138 psia, and the Refinery/Chao-Seader property method is used. This example uses 26 stages, and you run Aspen Plus to see what the split is. (Notice that you cannot easily set the split and find the number of stages or reflux ratio needed to achieve it.) Set the reflux ratio to 3.44 and enter the feed on the thirteenth stage. 

Use Aspen Plus and model each distillation column using the DSTWU model as shown in Figure 6.9. First, specify the split of key components for the light component you want 99 percent out of the top and for the heavy component you want 1 percent out of the top. The other components will be split according to the Fenske equation [Eq. (6.3)]. 

The monomer feed is converted into Polyamide-6 by polycondensation and polyaddition reactions [930]. This reaction step can be realized by a complex reactor which can be modeled as a sequence of stirred tank and plug-flow reactors. An exemplary model flowsheet comprising two reactors (CSTR) with an intermediate water separation (Split) is shown in Fig. 5.20. Such a model of the reaction section can be analyzed by means of Polymers Plus, an extension of Aspen Plus for handling polymer materials [513]. 

The steady state simulations (QUIKBAL and ASPEN) comprise a number of flashes exchangers, splits, compressors, towers and tailor-made fortran subroutines which are structured in sequential modular form. 

Solution. We present results of regression obtained in ASPEN Plus with NRTL model. Experimental data comes from Landolt-Bomstein. Fig. 6.21 displays the comparison of data at 1.033 at when both VLE and LLE data have been combined. The accuracy is excellent. Both immiscible region and position of the azeotrope are correctly described. Fig. 6.22 displays at the split temperature of 73.2 C. The characteristic concave shape is reproduced. As before, the variation is sharper at the water-rich zone limit. 

Computer simulation gives more insights. Table 9.2 presents some results obtained with ASPEN Plus. The direct sequence is more difficult, particularly the first split, where about 80 stages are necessary to get 99.8% purity acetone. 

As illustrated throughout this section, process simulators have extensive facilities for preparing phase-equilibrium diagrams T-x-y, P-x-y, x-y,... ), and residue curve maps and binodal curves for ternary systems. In addition, related but independent packages have been developed for the synthesis and evaluation of distillation trains involving azeotropic mixtures. These include SPLIT by Aspen Technology, Inc., and DISTIL by Hyprotech (now Aspen Technology, Inc., which contains MAYFLOWER developed by M.F. Doherty and M.F. Malone at the University of Massachusetts). 

The total feed of 2300 lb mol/h of a binary mixture of 80 mol% methanol and 20 mol% water is split between the two columns to exactly balance the heat duties in high-pressure column condenser (QChp) and the low-pressure reboiler (QRlp)- Both columns produce 99.9 mol% methanol distillate streams and 99.9 mol% water bottoms streams. The required reflux ratios are 1.1 and 1.5 in the low- and high-pressure columns, respectively. Column diameters are 6.5 and 5.2 ft in the low- and high-pressure columns, respectively. Temperature profiles are given in Figure 8.27. The NRTL physical properties are used in the Aspen simulations. 

Decanter Models in Aspen. Up to this point, we have been using the Decanter model in the simulations. It assumes that there are only two phases, both liquid, and that the decanter pressure is fixed at the specified design value (pressure does not change with temperature or composition). These assumptions do not reflect reality but appear to suffice for steady-state design. In a real decanter, there is a vapor space above the two liquid phases, and pressure will vary with compositions and temperatures unless an inert gas is used to keep a constant pressure via a vent-bleed split-ranged valve setup. 

II. Pressure effects—Changing split. Suppose we want to split between the C2 and the C3 conpounds (ethane and ethylene are in distillate and ever54hing else in bottoms). Change the value for distillate flow rate in Aspen Plus to achieve this. Operate at pressure of 15 atmospheres. Use the same settings as previously. Run Aspen Plus. Compare the temperature in the condenser to the tenperature in run I.c. (also at 15 atm). What can you conclude Report distillate and bottoms mole fractions and temperatures. 

Design Azeotrope Search in the Aspen Plus menu bar. In this dialog box, all components are selected for the search, the operating pressure is selected as 1 atm, and the property method of NRTL is also selected. Because liquid-liquid splitting is observed in this system, valid phases of VAP-LIQ-LIQ should be selected. The selection is shown in Figure 2.13. 

Aspen 5,600 460 Relatively free from splitting when nailed ... 

---