Process simulation software

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Because most thermoset composites cure by a thermally activated reaction, a complicated heat transfer process occurs during solidification, the result of an exothermic cross linking reaction in the resin. The complications of thermoset resin curing are compounded by the competing mechanisms of 

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Two extremes are encountered in process simulator software. At one extreme the process model comprises a set of equations (and inequalities) so that the process model equations form die constraints for optimization, exactly the same as described in previous chapters in this book. This representation is known as an equation-... 

At the core of many of these algorithms for solvent substitution is a method for predicting the properties of proposed molecules, given only the molecular structure. Much work has been done in this area alone, and several programs have been developed to guide this process. Some of these programs are listed in table 9.1. Additionally, process simulation software such as Aspen Plus contain several different approaches for the prediction of properties from molecular structure. 

Process simulation is a key tool in computer-assisted solvent substitution. More complicated than the prediction of physical and chemical properties is the prediction of more loosely defined molecular characteristics such as toxicity. These properties are not traditionally included in process simulation software, so special attention must be paid to their prediction. 

As with mass balances, energy balances for complex design problems are most easily set up and solved using commercial process simulation software, as described in Chapter 4. 

Process simulation software can also be used to help build simple energy balances in spreadsheet models, for example, by entering stream data to calculate mixture heat capacities, to calculate stream enthalpies, or to estimate heats of reaction. 

How to use commercial process simulation software to build a process heat and material balance model... 

If a flowsheet is not converged, or if the process simulation software runs and gives a statement converged with errors, then the results cannot be used for design. The designer must take steps to improve the simulation so that a converged solution can be found. 

Note This problem can be solved without using process simulation software. Start the mass balance at the reactor inlet (after the recycle streams have been added) and assume 100 kgmol/h of benzene at this point. 

Outline an overall process flow sheet and material balance including solvent recovery and recycle. This should be done with the aid of process simulation software. [See Seider, Seader, and Lewin, Product and Process Design Principles Synthesis, Analysis, and Evaluation, 2d ed. (Wiley, 2004) and Turton et ah. Analysis, Synthesis, and Design of Chemical Processes, 2d ed. (Prentice-Hall, 2002)]. In the flow sheet include methods needed for controlling emissions and managing wastes. Carefully consider the possibility that impurities may accumulate in the recycled solvent, and devise methods for purging these impurities, if needed. 

C, a typical residence time is 15 seconds. For a pipe reactor operating at 600°C, a typical residence time is 60 seconds. Given a target residence time, the approximate process volume required for a SCWO reactor may be calculated if the process fluid density is known. Density of the SCWO reactor fluid may be estimated by adding the densities of the gas and liquid at reactor temperature and at their respective partial pressures. When process simulator software is used, recommended equations of state are Redlich-Kwong-Soave (RKS, generally available) and SR-POLAR (for ASPEN). ... 

The CAPE-OPEN project may serve for illustration [566]. This project has been funded by the EU in parallel to the IMPROVE project with participation of two IMPROVE research teams. The project successfully defined open interfaces for the major modules of process simulation software. Despite the fairly narrow scope, the financial effort has been substantial. The project could only be successful because of an active participation of the relevant software vendors and their clients who had to sort out not only the technical but also the commercial issues. The academic partners role has been of an advisory and quality assurance type. Today, a few years after completion of the project, significant efforts are spent by a Co-LaN, a non-for-profit interest group which maintains and extends the standard [997]. Only due to continued efforts of Co-LaN, the CAPE-OPEN standard is implemented readily by the smaller software companies and only reluctantly by the major vendors. 

Bofh EOS and activity-coefficient methods require binary interaction parameters. In process simulation software, the necessary parameters may already be built into a data bank. Sometimes, parameters for the system of interest may be found in the literature. If not, however, the parameters must be fitted to mixture data. 

In this section, a pilot-scale process that has been developed specifically for the production and purification of AdVs for gene therapy [80] is analyzed and evaluated for large-scale manufacturing with the use of the process simulator software SuperPro Designer (Intelligen, Inc., Scotch Plains, NJ). The major objective of the... 

The phase behavior predictions for the reaction mixture were made via the Peng-Robinson equation of state and ChemCAD process simulation software. The calculation method was shown to be accurate to within 10% compared to data from Schneider [20], Olds et al. [21], and Poetmann and Katz [22], Table 1 shows the estimated critical properties for various systems. 

The value of the binary interaction parameter k(j must be estimated or found by fitting mixture data. Our brief introduction to this approach has been based on the Redlich-Kwong equation, but the procedure can be implemented with any PvTx equation. More generally, the approach discussed here can provide accurate predictions of fluid properties at high T and P using model parameters fit at low T and P. The procedure is now routinely used in process simulation software. 

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