Model Aspen HYSYS

A related problem is the conversion of kinetic lumps back to fractionation lumps required to build rigorous fractionation models. For our models. Aspen HYSYS gives a method to transition the kinetic lumps to pseudocomponents based on boiling points typically used to model the petroleum fractionation. We also propose an alternative technique that can provide similar results using methods developed in earlier in this section. Essentially, we must convert the kinetic lumps back into a TBP curve. The key steps in converting the kinetic lumps to pseudocomponents based on boiling point are ... 

Figure 5.54 shows the Feed Data tab from the Reformer sub-model. The Feed Type is a basic set of relationships and initial values for the all kinetic lumps in the reactor model. Aspen HYSYS uses bulk property information such as density, distillation curves and total PNA content in conjunction with the feed type to predict the composition of feed lumps to the model. The Default type is sufficient for hght-to-heavy naphtha. However, there is no guarantee that a particular feed type represents the actual feed accurately. Aspen HYSYS will attempt to manipulate the feed composition to satisfy bulk property measures given. In general, we advise users to develop a few sets of compositional analysis to verify the kinetics lumps calculated by Aspen HYSYS. We discuss a process to verify these lumps later. 

Nowadays, several process simulators such as Aspen Plus and Aspen HYSYS are commercially available for simulating complete chemical processes. Common process units and a property database for numerous chemicals are available in such simulators. However, models for less common and/or new process units (for example, membrane separation) are not readily available in the simulators, but they may be available in the literature or can be developed from first principles. Mathematical model for a new process unit can be implemented in Aspen Custom Modeler (ACM), and then it can be exported to (included in) Aspen Plus or Aspen HYSYS for simulating processes having a new process unit besides common process units such as heat exchangers, compressors, reactors and columns. Process simulators for simulation and ACM for implementing models of new process units are... 

As mentioned earlier, some process models are not available in the simulators such as Aspen Plus. In such situations, ACM can be used to implement models available in the literature or newly developed models. Subsequently, these ACM models can be included in Aspen Plus and/or Aspen HYSYS for use like built-in models in any process. The above model for gas separation using membrane (Section 4.2.3) can be implemented and solved in ACM see Appendix 4A for more details on the ACM model for no permeate mixing membrane module. In order to implement the membrane model in ACM, all chemicals are defined from the component list in the Aspen Properties User Interface program, and then... 

For using the model in Aspen Plus, the membrane model in ACM has to be saved as a. msi file using the export wizard (right click on the NGSep in All Items pane). For this, Microsoft C++ compiler is required (ACM V7.3 requires Professional/Premium/ Ultimate edition of Microsoft Visual Studio 2008, whereas ACM V8.0-8.6 requires Professional/Premium/Ultimate edition of Microsoft Visual Studio 2010). After this, the. msi file can be installed in Aspen Plus and/or Aspen Hysys library for use like built-in models in simulating chemical processes... 

The membrane module used for the simulation of the HMD process in Aspen HYSYS is developed using Aspen Custom Modeler (ACM) v8.4, and then compiled using Microsoft Visual Studio 2010. 

Here, F, Zf and h are, respectively, the molar flow rate, mole fraction of component of i and total enthalpy, all in cell k their subscripts, ret and perm, refer to retentate and permeate streams. Equations (10.4) and (10.5) are mass balances and mass-transfer equations for each of the components present in the membrane feed. The cross-flow model [Equations (10.3)-(10.7)] was implemented in ACM v8.4 and validated against the experimental data in Pan (1986) and the predicted values of Davis (2002). The Joule-Thompson effect was validated by simulating adiabatic throttling of permeate gas through a valve in Aspen Hysys. Both these validations are described in detail in Appendix lOA. 

The developed membrane model/ACM module was also validated against the results of Davis (2002). In his study, a mathematical model of a hollow-fiber membrane was developed in Aspen HYSYS for air separation. Parameters used in the simulation of this separation are given in Table 10.A.2. As can be seen in Table 10.A.3, the ACM model predictions are very close to the simulation results of Davis (2002), with a maximum difference of 0.41% in permeate O2 concentration. 

This chapter introduces the use of Aspen HYSYS to model a continuous gas absorption process in a packed column. The only imit operation contained in the Absorber is the Tray Section, and the only streams are the overhead vapor and bottom liquid products. There are no available specifications for the Absorber, which is the base case for all tower configurations. The conditions and composition of the column feed stream, as well as the operating pressure, define the resulting converged solution. The converged solution includes the conditions and composition of the vapor and liquid product streams. 

Oi, L. Aspen HYSYS Simulation of CO2 Removal by Amine Absorption from a Gas Based Power Plant, Proceedings of SIMS2007 Conference, The 48 Scandinavian Conference on Simulation and Modeling, pp. 73 - 81, Goteborg, October 2007. 

Tutorial Example of Modelling CO2 Capture Using Aspen HYSYS. 206... 

It should be noted that in ProMax, the TS WEET model can be used for MEA using a similar approach to that shown in Section 2.2. In Aspen HYSYS, MEA can be modelled using the DBR amine package (see Section 3.3). 

TUTORIAL EXAMPLE OF MODELLING CO2 CAPTURE USING ASPEN HYSYS... 

The ability to model Selexol-based unit operations in Aspen Plus or Aspen HYSYS was recently made possible by the inclusion of the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) physical property model. As in Aspen HYSYS (see Section 6.1.1), a single chemical DEPG be used as a proxy for the mixture. Simple example files for using PC-SAFT with Selexol for one- or two-unit operations are included with the Aspen Plus distributiOTi, and an example for using PC-SAFT in Aspen HYSYS is available for download to subscribers of the Aspen Technology support website. 

The information flow in the mathematical model coincides with the material flow in the process (the process simulator Aspen HYSYS is a ranarkable exception). This assumption allows us to gather the variables associated with the streams entering the unit and define the functions that calculate the variables for the output streams. 

The COSTALD correlation is quite accurate even at high reduced temperatures and pressures. Predicted liquid densities generally agree with measured values within 1-2% provided the errors in the critical property predictions are low. A potential problem can occur if the reduced temperature is greater than 1. There can be discontinuity from the Spencer-Danner equation in the density prediction which may cause some process models to fad. However, at a reduced temperature greater than 1, the equation of state becomes more accurate and can be used directly. Aspen HYSYS includes a smoothing approach (using the Chueh and Prausnitz correlation [16]) to ensure a smooth transition from the COSTALD densities to equation-of-state-based densities. 

Illustration of representative CDU data for modeling purposes (Section 2.7) Building a model based on collected data using Aspen HYSYS (Sections 2.8.1 to 2.8.3)... 

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