Software, simulations

Lott, D. H-, Simulation Software as an Aid to Process Synthesis, IChemE Symposium Series No. 109, IChemE, 1988. 

AIR-1 and PS-4 are used on-site for recording of A-scan data during the on-site inspection. UltraSIM is used for initial ultrasonic simulation, scan path generation and robot simulation (together with the ROBCAD robot simulation software), online control and monitoring of the real AIR-1 robot and finally for 3D reconstruction of ultrasonic A-scan data. 

The MathWorks Inc. (1993) SIMULINK Numerical Simulation Software - Reference Guide, The MathWorks Inc., Natick, Mass. 

There are commercially available clarifier simulation software for comprehensive (2D) analyzes of wastewater treatment processes in circular and rectangular clarifiers. With these software, you can predict processes like ... 

Bakker, A., Fasano, J., and Leung, D. E., Pinpoint mixing problems with lasers and simulation software, Chem. Eng., pp. 94-100, January 1994. 

Cost If simulation software is in place and trained staff available, computation is considered faster and less expensive than measurement. 

The above conditions are not robust because they are at the limit of the complete separation zone. The equilibrium theory neglects the dispersion phenomena and therefore the purity obtained under these flowrate conditions would be less than 100 % on a TMB system. Complex simulation software, which takes into account the dispersion phenomena, gives a more robust system with higher purities [57]. 

Using simulation software (essentially solving the mass balance equation in the transitory regime), one can show that the internal profiles of the products in the system are given by the profiles presented in Figure 10.6. Samples were taken between columns at half periods. 

Preparative chromatography has been used for chiral separations for years, but examples of multi-kg separations (and hence larger ones) were rare until recently. The development of SMB techniques (both hardware and simulation software) has made major breakthroughs in this field. The ability of SMB as a development tool has allowed the pharmaceutical manufacturer to obtain kilo grams quantities of enantiopure drug substances as well benefit from the economics of large-scale production. 

Process validation is the procedure that allows one to establish the critical operating parameters of a manufacturing process. Hence, the constraints imposed by the FDA as part of process control and validation of an SMB process. The total industrial SMB system, as described, is a continuous closed-loop chromatographic process, from the chromatographic to recycling unit and, with the use of numerical simulation software allows the pharmaceutical manufacturer rapidly to design and develop worst-case studies. 

The GEMM software on the ST-100 is not a stand-alone package, and it requires a front-end simulation software package that runs on the host to provide data and to send command requests. It was designed and written with CHARMM (Chemistry at HARvard Macro-molecular Mechanics) (14) as the primary front-end, but additional software packages, such as AMBER (15), have subsequently been modified to drive GEMM. 

In Section 42.2 we have discussed that queuing theory may provide a good qualitative picture of the behaviour of queues in an analytical laboratory. However the analytical process is too complex to obtain good quantitative predictions. As this was also true for queuing problems in other fields, another branch of Operations Research, called Discrete Event Simulation emerged. The basic principle of discrete event simulation is to generate sample arrivals. Each sample is characterized by a number of descriptors, e.g. one of those descriptors is the analysis time. In the jargon of simulation software, a sample is an object, with a number of attributes (e.g. analysis time) and associated values (e.g. 30 min). Other objects are e.g. instruments and analysts. A possible attribute is a list of the analytical... 

Often it is possible to consider the process or plant, as a system of independent sub-sets or modules, which are then modelled individually and combined to form a description of the complete system. This technique is also used in the large scale commercial simulation software, in which various library sub-routines or modules for the differing plant elements, are combined into a composite simulation program. 

Optimisation may be used, for example, to minimise the cost of reactor operation or to maximise conversion. Having set up a mathematical model of a reactor system, it is only necessary to define a cost or profit functionOptimisation and then to minimise or maximise this by variation of the operational parameters, such as temperature, feed flow rate or coolant flow rate. The extremum can then be found either manually by trial and error or by the use of a numerical optimisation algorithms. The first method is easily applied with ISIM, or with any other simulation software, if only one operational parameter is allowed to vary at any one time. If two or more parameters are to be optimised this method however becomes extremely cumbersome. 

A number of design calculations require a knowledge of thermodynamic properties and phase equilibrium. In practice, the designer most often uses a commercial physical property or a simulation software package to access such data. However, the designer must understand the basis of the methods for thermodynamic properties and phase equilibrium, so that the most appropriate methods can be chosen and their limitations fully understood. 

To calculate the enthalpy of liquid or gas at temperature T and pressure P, the enthalpy departure function (Equation 4.78) is evaluated from an equation of state2. The ideal gas enthalpy is calculated at temperature T from Equation 4.81. The enthalpy departure is then added to the ideal gas enthalpy to obtain the required enthalpy. Note that the enthalpy departure function calculated from Equation 4.78 will have a negative value. This is illustrated in Figure 4.9. The calculations are complex and usually carried out using physical property or simulation software packages. However, it is important to understand the basis of the calculations and their limitations. 

The calculation in this example can be conveniently carried out in spreadsheet software. However, many implementations are available in commercial flowsheet simulation software. 

Unfortunately, the analysis of chemical absorption is far more complex than physical absorption. The vapor-liquid equilibrium behavior cannot be approximated by Henry s Law or any of the methods described in Chapter 4. Also, different chemical compounds in the gas mixture can become involved in competing reactions. This means that simple methods like the Kremser equation no longer apply and complex simulation software is required to model chemical absorption systems such as the absorption of H2S and C02 in monoethanolamine. This is outside the scope of this text. 

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