Computer programs EVAPOR

The occurrence matrix for the evaporator problem was formed and analyzed using the computer program listed in Appendix A. Figure 21 is the... 

In the course of evaporative evolution, it is usually valuable to compare individual solute concentrations to a conservative solute. In general, this is chloride in less concentrated brines, and bromide in waters supersaturated with respect to halite (Eugster and Jones, 1979). Solute behavior plotted this way takes one of the several diagnostic routes as shown in Figure 7. In the later stages of chemical evolution, the ratios with respect to the alkalies and sulfo-chloride become important, and it is advantageous to consider associations within the entire major solute matrix. A useful tool for this purpose is normative analysis (Jones and Bodine, 1987). The computer program SNORM (Bodine and Jones, 1986) calculates the... 

In this paper, I discuss two examples of computer programs that perform calculations that are impossible by hand methods. Both have been published previously but are presented here to illustrate the power of the computer in solving practical problems. Both perform calculations using data from a computerized data file of individual solvent properties. The first predicts evaporation... 

The pyrolysis high resolution mass spectrometry (PyHRMS) technique has been described in detail previously (20). Briefly, the coal sample was placed on a platinum rhodium mesh on the end of a probe as a slurry. After the solvent had evaporated, the probe was inserted into the mass spectrometer and positioned within 5 mm of the source. The probe, which had been previously calibrated with an infra-red thermometer, was computer-controlled to give a temperature profile beginning at 100°C and increasing at 50°C/min to 800 C. The precise masses were matched to their corresponding chemical structures by computer programs developed in-house. This technique results in the relatively slow vacuum pyrolysis of the coal sample. 

In practice, such mirrors are produced by evaporation techniques controlled by a corresponding computer program. In Fig. 6.33 the variation of the refractive index for the different dielectric layers is shown for a mirror with negative GDD, and in Fig. 6.34 the reflectivity and the group delay is plotted as a function of wavelength for mirrors with negatively and positively chirped graded-index profiles. In combi-... 

Table 10.7 lists many of the amine-type solvents in terms of descending evaporation rates where the standard solvent is /i-butyl acetate with an evaporation rate of 1.0. The solvent s boiling points and Hansen solubility parameter values are also listed so as to enable a comparison of both a solvent s relative evaporation rate and solvency for a resin or polymer. This list can also be used to find a substitute solvent with properties similar to a solvent that should be replaced. These comparisons can also be made with one of the computer programs discussed in Chapter 19. 

The Dow Chemical Company has a solvent related computer program, Chemcomp, which simulates evaporation profiles for solvent blends. Other features include the ability to measure the effects of humidity on evaporation, calculation of the Hansen solubility parameters for the solvent blend, and inclusion of data on the relative rate of evaporation of the blend at 90% as compared to a standard n-butyl acetate being equal to 1.0. More information on Chemcomp and related solvent modeling computer programs can be obtained from Dow at 1-800-258-2436... 

The Eastman Chemical Company also has a solvent selection computer program for customer assistance. The data files allow the selection of replacement solvent blends for coatings and ink formulations. The typical evaporation rate profiles and solubility parameter values are available outputs from the program. More information on the solvent selection computer programs are available from the Eastman Chemical representative at 1-800-327-8626. 

Each fraction was evaporated to dryness in 10-ml pear-shaped flasks, redissolved in a small amount of methylene chloride, and gas chromatographed. GC conditions were as follows column, 6 ft X 0.125 in. od stainless steel packed with 3% OV-17 on 100-120 mesh Gas-Chrom Q temperature program, 70-330°C at 12°/min, holding at the flnal temperature for up to 20 min and carrier gas flow rate, 28 ml/min. Fractions containing very little material or with GC patterns very much like adjoining fractions were combined. These fractions were then analyzed on the GC-MS computer system to obtain mass spectral data on the individual components. For certain fractions additional information was gained from ultraviolet spectra. 

The Hewlett-Packard (HP) 7686 PrepStation System workstation allows you to write a program that will condition, load, rinse, and elute your SPE columns (Fig. 10.4, Table 10.4). A dedicated DOS-based ChemStation computer system by HP is required to run the instrument. The software uses a Menu Selectable Approach. The instrument operates in a serial mode and works with HP s disposable SPE cartridges. Individual flow rates for condition, load, rinse, and elute are selected. The workstation may be used to perform volumetric dilutions, sample mixing, bar-code reading, evaporation, and derivatization. When used with an HP 1050 HPLC or HP 5890 GC direct injections are possible. The instrument is also available in a stand-alone... 

A linear programming technique is described which selects mixed solvents based on specifications of the ffo, 8p, end SH solubility parameters, evaporation rates, and other significant parameters of a solvent blend. Suggestions are made for setting the various restrictions and for setting procedures of data processing. For simpler cases of solvent selection, recourse to a computer is not necessary. Use of a solvent improvement cost factor, 8 J cost, then leads to optimum formulations since one can determine which solvents increase solubility at least cost. 8 is given by y/ 8P2 -(- 8H2. 

The properties of the optimized solvent blend generally meet the restrictions of minimum solvency and either a lower or upper limit on average evaporation rate. The use of two equations to place upper and lower bounds on the evaporation rate is recommended. If the evaporation rates are too restrictive, the computer tends to select solvents which are more expensive and of better quality. It is possible to set such stringent or unreasonable restrictions that no solution is acceptable to the computer. It is instructive at times to eliminate the evaporation rate restrictions altogether evaporation rate can be controlled by the solvents the computer is allowed to consider. Our solvent selection programs have operated satisfactorily with the relative evaporation rate system based on n-butyl acetate as 100 although this is an arbitrary choice which has not been evaluated by comparison. 

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