ASPEN program system

A major development effort has been underway at M.I.T. from 1976 to 1979 to develop a next-generation process simulator and economic evaluation system named ASPEN (Advanced System for Process ENgineering). The 150,000-line computer program will simulate the flowsheet of a proposed or operating plant. In addition to calculating detailed heat and material balances,... 

The ASPEN system is on schedule for a working version to be completed October, 1979. The program system will be comprised of about 150,000 lines of FORTRAN code and data for physical... 

Merson, H., Black, R. E., Mills, A. J. (Eds.). (2006). Complex humanitarian emergencies. In International public health Diseases, programs, systems, andpolicies (pp. 439-510). Gaithersburg, MD Aspen. 

This is the fun (and frustration) of chemical reaction engineering. While thermodynamics, mass and heat transfer, and separations can be said to be finished subjects for many engineering apphcations, we have to reexamine every new reaction system from first principles. You can find data and construct process flowsheets for separation units using sophisticated computer programs such as ASPEN, but for the chemical reactors in a process these programs are not much help unless you give the program the kinetics or assume equihhrium yields. 

To study different operating conditions in the pilot plant, a steady-state process simulator was used. Process simulators solve material- and energy-balance, but they do not generally integrate the equations of motion. The commercially-available program, Aspen Plus Tm, was used in this example. Other steady-state process simulators could be used as well. To describe the C02-solvent system, the predictive PSRK model [11,12], which was found suitable to treat this mixture, was applied. To obtain more reliable information, a model with parameters regressed from experimental data is required. 

Several important types of reactions are considered in the following sections. The equations describing each of these systems are developed. The steady-state design of CSTRs with these reactions are discussed, using Matlab programs for hypothetical chemical examples and the commercial software Aspen Plus for a real chemical example. 

The dynamics and control of a number of tubular reactor systems have been studied in this chapter. Both adiabatic and cooled tubular reactors have been explored in both isolation and a plantwide environment. Ideal systems have been studied using Matlab programs. Real chemical systems have been studied using Aspen Dynamics. 

Another potential advancement is permitted in the ASPEN system. Tear streams can be designated as desired, so that a user might define blocks or series of blocks and simulate these sets as quasi-linear blocks. The convergence method could utilize this information and solve the material (and energy) balances explicitly. In this way, a simultaneous modular architecture could be utilized. Implementation of these programs will be for later enhancements of ASPEN, not the initial version. 

As with the rest of ASPEN, the cost estimation and economic evaluation system will be modular in design there will be one program module for each equipment class, and it will be easy for users to add their own costing modules. 

Akashah et al. optimum feed, 118.119 Albright random cells, 542 AMSYM program, 171,192 ASPEN system, 163 ASPENPlus system, 163, 177,179 187 192... 

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 CASST/CC system has been modelled within the process flow simulation program ASPEN , "Hie major assumptions made for the CASST process are given in table 4. For the combined cycle the assumptions described by Faay et. al. (6) have been used. 

As in Example 4, the EXTRACT block in the Aspen Plus process simulation program (version 12.1) is used to model this problem, but any of a number of process simulation programs such as mentioned earlier may be used for this purpose. The first task is to obtain an accurate fit of the liquid-liquid equilibrium (LLE) data with an appropriate model, realizing that liquid-liquid extraction simulations are very sensitive to the quality of the LLE data fit. The NRTL liquid activity-coefficient model [Eq. (15-27)] is utilized for this purpose since it can represent a wide range of LLE systems accurately. The regression of the NRTL binary interaction parameters is performed with the Aspen Plus Data Regression System (DRS) to ensure that the resulting parameters are consistent with the form of the NRTL model equations used within Aspen Plus. 

The tools used in CAPE could be specified as solvers, simulators, databases, equipment designers, and decision support systems. Several tools, such as simulators, databases, and decision supporting systems, are often embedded as one computing environment, e.g., ASPEN or ICAS. A few examples of the existing programs and environments are given in Table 1. 

In recent years, property information systems have become widely available in computer packages. Some are available on a stand-alone basis, such as PPDS2 (1997), while others are available within the chemical process simulators, such as ASPEN PLUS, HYSYS.Plant, PRO/n, CHEMCAD, BATCH PLUS, and SUPERPRO DESIGNER. Commonly, constants and parameters are stored for a few thousand chemical species, with programs provided to estimate the property values of mixtures, and determine the constants and parameters for species that are not in the data bank using estimation methods or the regression of experimental data. Virtually all of the property systems estimate the properties of mixtures of organic chemicals in the vapor and liquid phases. Methods are also provided for electrolytes and some solids, but these are less predictive and less accurate. 

Any of the commercially available chemical engineering programs (e.g. Aspen , Chemcad , and PROII ) can be used for calculation and simulation of hybrid system. An additional modulus has to be introduced into the program that in rather simple terms describes the membrane system. In a first approach it is necessary only to check the relation between feed flow and concentration on the membrane area, and the product quality and amount. Even a modified version of Eq. (21), relating feed flow and concentration, product flow and concentration, and membrane area would be sufficient for a first design. 

Aspen Plus provides feature called Conceptual Design that offers another approach to the problem (a design approach). In this method, the product specifications are set at both ends of the column, as is a reflux ratio. Then, the program performs tray-to-tray calculations, both up and down the column, creating composition profiles for both the rectifying and stripping sections. If these two composition profile intersect, the reflux ratio selected is above the minimum, and the number of trays in both sections is now known. The method is applicable to ternary systems with a single feed stream. 

We saw in Section 15.6 that a Fickian mass-transfer analysis can lead to logical inconsistencies when extended to three or more conponents. Thus, a fundamental rate analysis of multiconponent distillation must be based on the Maxwell-Stefan mass-transfer model extended to nonideal multiconponent systems fSection 15.7.7T Since the significant detail required for these calculations is beyond the scope of an introductory textbook, the methods are summarized in enough detail to explain what the commercial simulator does (Lab 13 in appendix to Chapter 161 but not in enough detail to write a program of your own. Readers interested in the conplete details are referred to Taylor and Krishna (1993) and Aspen Plus r2QlQT... 

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