Aspen process simulator

The local composition model (LCM) is an excess Gibbs energy model for electrolyte systems from which activity coefficients can be derived. Chen and co-workers (17-19) presented the original LCM activity coefficient equations for binary and multicomponent systems. The LCM equations were subsequently modified (1, 2) and used in the ASPEN process simulator (Aspen Technology Inc.) as a means of handling chemical processes with electrolytes. The LCM activity coefficient equations are explicit functions, and require computational methods. Due to length and complexity, only the salient features of the LCM equations will be reviewed in this paper. The Aspen Plus Electrolyte Manual (1) and Taylor (21) present the final form of the LCM binary and multicomponent equations used in this work. 

Under the processing agreement with the Crown, NZSFC is required to predict the operating efficiency of the complex for varying feedstock compositions. This is achieved using the Aspen Process Simulator which has been jointly developed by NZSFC and Davy McKee for this purpose. 

Example 11.7 hints at the complications that are possible in reactive gas absorption. Gas absorption is an important unit operation that has been the subject of extensive research and development. Large, proprietary computer codes are available for purchase, and process simulation tools such as Aspen can do the job. However, as shown in Example 11.8, simple but useful approximations are sometimes possible. 

Databases in process simulators such as Aspen (1998), HYSYS (1998), and ProII (1998). 

Process simulation ASPEN Nanomaterid processing Trained Free... 

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. 

Aspen Plus Steady-state process simulation www.aspentec.com... 

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. 

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. 

As a consequence, corporations operating PUREX plants have been using sophisticated process simulation codes, including the PAREX code in France (45-47), SpeedUp (Aspen Plus) in the UK (48), and SIMPSEX code in India (49-51). Argonne Model for Universal Solvent Extraction (AMUSE) code in the United States was contrived not only for PUREX, but for UREX+ processes (52), which will be mentioned later. In Japan, similar efforts have also been made (53-55). 

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. 

The process simulation code Aspen-HYSYS 3.2 has been used for residential PEM fuel cell system calculations. Natural gas has been simulated as three different sources for hydrogen production. The chemical compositions of the natural gas fuel are summarized in Table 1. The average molecular weight of natural gas is around 16.6 kg/kmol. All simulation studies are performed based on this composition. 

S 2] With the steady-state process simulator Aspen Plus , thermodynamic models for the sulfur-iodine cycle given in [132] are combined with chemistry models which describe the dissociation and precipitation reactions. 

These examples underline the fact that macro-scale process simulation tools such as Aspen Plus will have to be supplemented by micro-type unit operations as introduced by the FAMOS initiative which consider the location of a fluidic cell in the device and does not assume a perfect mixing, piston flow or uniform heat transfer coefficient [13]. 

To conclude our examples of Aspen Dynamics simulation of tubular reactor systems, we study a very important industrial process for the production of methanol from synthesis... 

Several authors have already developed methodologies for the simulation of hybrid distillation-pervaporation processes. Short-cut methods were developed by Moganti et al. [95] and Stephan et al. [96]. Due to simplifications such as the use of constant relative volatility, one-phase sidestreams, perfect mixing on feed and permeate sides of the membrane, and simple membrane transport models, the results obtained should only be considered qualitative in nature. Verhoef et al. [97] used a quantitative approach for simulation, based on simplified calculations in Aspen Plus/Excel VBA. Hommerich and Rautenbach [98] describe the design and optimization of combined pervaporation-distillation processes, incorporating a user-written routine for pervaporation into the Aspen Plus simulation software. This is an improvement over most approaches with respect to accuracy, although the membrane model itself is still quite... 

Although ASPEN-Plus is widely used to simulate petrochemical processes, its uses for modeling biomass processes are limited owing to the limited availability of physical properties that best describe biomass components such as cellulose, xylan, and lignin. For example, Lynd et al. (1) used conventional methods to calculate the economic viability of a biom-ass-to-ethanol process. However, with the development by the National Renewable Energy Laboratory (NREL) of an ASPEN-Plus physical property database for biofuels components, modified versions of ASPEN-Plus software can now be used to model biomass processes (2). Wooley et al. (3) used ASPEN-Plus simulation software to calculate equipment and energy costs for an entire biomass-to-ethanol process that made use of dilute-H2S04 acid pretreatment. 

In 2006, GA participated in a study conducted by the Savannah River National Laboratory (Summers, 2006). The S-I process was coupled to a VHTR with a required helium return temperature near 600°C. To efficiently match temperature requirements with available heat, a design was developed to supply HI decomposition section energy with recovered heat from the sulphuric acid decomposition section. For the purposes of comparison and analysis in this paper, the GA flow sheets will refer to this design, and CEA flow sheets will refer to a design in which helium supplies heat to both acid decomposition sections. CEA uses ProSimPlus for flow sheet analysis, and GA uses Aspen Plus . A previous study (Buckingham, 2008) showed that the two process simulators give similar calculated results when the same unit operations and stream compositions are modelled, although different thermodynamic models are used for the calculations. 

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,... 

In many process simulations, the user is responsible for structuring all computations and the computational sequence directly. In ASPEN the system is capable of complete automatic determination of the computational sequence. Alternatively, the user can select certain tear streams and can, in fact, easily specify the entire sequence. 

Although the ASPEN process models can be put together to simulate many types of processes, it may still be necessary to use specialized or proprietary models. Such would be the case, perhaps, for a specific type of a coal gasification reactor. 

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... 

VSA processes were simulated using the Aspen ADSIM, a commercial adsorption process simulator from AspenTech Co., with the following governing equations ... 

Use a commercial flowchart simulation program such as HYSYS or ASPEN to simulate the ammonium nitrate manufacturing process described in Example 10.3-3. 

Throughout this book, we have seen that when more than one species is involved in a process or when energy balances are required, several balance equations must be derived and solved simultaneously. For steady-state systems the equations are algebraic, but when the systems are transient, simultaneous differential equations must be solved. For the simplest systems, analytical solutions may be obtained by hand, but more commonly numerical solutions are required. Software packages that solve general systems of ordinary differential equations— such as Mathematica , Maple , Matlab , TK-Solver , Polymath , and EZ-Solve —are readily obtained for most computers. Other software packages have been designed specifically to simulate transient chemical processes. Some of these dynamic process simulators run in conjunction with the steady-state flowsheet simulators mentioned in Chapter 10 (e.g.. SPEEDUP, which runs with Aspen Plus, and a dynamic component of HYSYS ) and so have access to physical property databases and thermodynamic correlations. 

Process simulators are used as an aid in the formulation and solution of material and energy balances. The larger simulators can handle up to 40 components and 50 or more processing units when their outputs are specified. ASPEN, PROSYS, DESIGN II, and HYSIM are examples of such process simulators. 

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