Design computer programs

More recently, the Southern Gas Association s Gas Machinery Research Council and Pipeline and Compressor Research Council cooperated with Southwest Research Institute to develop a software package that enhances reciprocating compressor operation. Several major American and foreign compressor manufacturers (and some other interested companies) have cooperated with Southwest Research Institute or developed their own proprietary pulsation-reduction design computer programs. 

It is possible that metal removal is the result of a mechanical process, with solid (Zn3(As04)2 removed by filtration. To examine this, we modeled mineral stability using a custom designed computer program. 

NMR spectroscopy derives its usefulness, in large measure, from its ability to detect constitutional symmetry. If constitutional symmetry is not taken into account in synthetic design computer programs, a redundancy of pathways may result. 

The similarity judgments are then analyzed by one of a number of specially designed computer programs that have been detailed by Schiffman, Reynolds and Young ( .) Some programs, such as INDSCAL, ALSCAL, and MULTISCALE, not only provide multidimensional arrangements of molecules based on their flavor similarity but provide quantitative measures that delineate the individual differences in response for each subject as well. The... 

Next, enter the data presented above into the Mathcad sieve-tray design computer program of Appendix E. Since the dimensions of the tray are known, the fractional approach to flooding is adjusted until the tray design coincides with the tray dimensions determined in part (a) of this example. Convergence is achieved at a value of/= 0.431. This means that at the bottom of the distillation column the gas velocity is only 43.1% of the flooding velocity. Other important results obtained from the program are as follows ... 

A balance has to be maintained in designing computer programs for implementing computational chemistry methods. On the one hand, sufficient devices should exist to allow a user to obtain results with an acceptable precision on the other, the programs should be as efficient as possible. These desiderata are, to a large extent, mutually exclusive. 

Most distillation and equilibrium parts of process-design computer programs (e.g.. Aspen, ChemCad, ProMax) report A, values for each species in the VLE data for mixtures, and some distillation programs report a. It must be clear from their definitions that they are made up from values of the y, and Xi. The computer programs mostly first compute the y and Xi, by the methods shown in the rest of this chapter and the next, and then compute and report the A, and a values for the convenience of users who prefer that formulation the, x, and y are the basic values. The common hand-calculation methods of estimating VLE are presented in terms of the A values in Section 8.9. 

If we must perform an 5 or V specified flash, the procedure is the same as for an adiabatic (H specified) flash. We guess a final T and P, solve for V/F and then the mol fractions, and compare the computed 5 or V with the specification. If the specification is not met, we adjust the guessed T and P and repeat the calculation until agreement is reached. This is seldom done by hand, but is offered as an option in some process-design computer programs. 

Current process design computer programs mostly calculate high-pressure VLE using cubic EOSs, of which the SRK is one of the most popular. The procedure is as illustrated in Example F.5/10.3. 

So far this chapter has presented a description of the most common (and interesting and important) types of LLE. There are ample LLE data in the literature, and the experiments to determine LLE (of nontoxic liquids at modest T and P) need not be terribly expensive or difficult. So we could simply assume that we will look up or measure any LLE data we need. Current process design computer programs can estimate such LLE data from theory with fair-to-good accuracy much more quickly and cheaply than we could find it in the library or the laboratory. This section shows the fundamentals of that theory and some simplified (hand or spreadsheet calculable) versions of the more complex algorithms in those computer programs. 

We rarely have data on gas phase nonideality, and normally simply use the L-R rule. However modem process design computer programs often compute using equations of state... 

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