MACS PACK

Before diseussing the turbomaehinery management attributes of digital systems, it is helpful to review the hardware, software, and MACS PACK eomponents. 

The hydrodynamic theory of the penetration of targets by lined cavity jets was developed, according to Cook (Ref 7, p 252), independently by Pugh (Birkhoff s et al Ref 2) and by Hill et al (Ref 1). Pack Evans (Refs 3 4) discussed the steady-state theory of penetration in which the jet-velocity. distribution was ignored and the penetration velocity was assumed constant. Pugh, 8t Eichelberger (Refs 5 6) discussed the nonsteady-state of jet penetration in which, the actual velocity distribution in the jet was taken into account as well as the variation of the velocity of penetration with.depth These theories are discussed by Cook (Ref 7) Refs 1) R. Hill, N.F. Mott D.C. Pack, Unpublished "Ministry of Supply Report, January 1944 2) G. Birkhoff, D.P. Mac-... 

Gow-Mac has recently marketed a refractometer which is based on the Christiansen effect . The system consists of a sample flow cell which is packed with a solid material having the same refractive index as the mobile phase. Visible light is therefore transmitted directly through the cell. When a solute enters the cell, the refractive index of the mobile phase alters, causing a change in the quantity of transmitted light which reaches the detector. A variety of solid materials is available for use with a large number of solvent systems. 

HcKp (Fig. 8.3e). This packing is a modified Pall ring with a mac open structure and an enhanced arrangement of internal drip tabs (8m. 

This device has been manufactured by GOW-MAC Inc., who claimed it had a sensitivity of 1 x 10 refractive index units. This would be equivalent to a sensitivity of 9 x 10 g/ml of benzene (refractive index 1.501) eluted in w-heptane (refractive index 1.388). The cell volume was kept to 8 pi, a little large for modern sensors but small enough to work well with normal 4.6 mm I.D. columns. Different cells packed with appropriate materials were necessary to cover the refractive index range of 1.31 to 1.60. A diagram of the Christiansen detector is shown in figure 5. 

Another possibility for modeling packed-bed reactors involves the use of a so-called unit cell approach where a suitable periodic structure in the packing is identified and subsequently used to define the boundaries of the computational domain. Due to the geometrical complexity the fluid flow (and other relevant equations have to be formulated and solved in curvilinear coordinates. In fact this approach has been followed for example, by Guj and De Matteis (1986) who used a MAC-like scheme (Welch et ai, 1965) to solve the Navier-Stokes equations. For random packings the unit cell approach becomes much more difficult due to the fact that a suitable periodic structure is difficult to define. 

Figure 16.22 Breakthrough curve normalized to the inlet concentration of CH4 and C)2 carried by helium through a 1 x 30 cm column packed with a microporous carbon (Kureha MAC). Dimensionless time, t = tug/L. Symbols show experimental results, the lines the calculated profiles with the models indicated. The variation of the gas velocity along the column was accounted for. Reproduced with permission from L.. P. van den Broeke, R. Krishna, Chem. Eng. Sci., 50 (1995) 2507 (Fig 12).

Isopropanol dehydration over AI2O3 calcined at different temperatures was studied in a pyrex glass steady state system. The fixed bed (50 mg) tubular reactor was operated at differential regime (% conversion<10), in the 423temperature range and atmospheric pressure. The feed was composed of a N2 (Praxair) stream saturated with isopropanol at room temperature. The analysis of effluents from the reactor was carried out by gas chromatography with a Gow-Mac Series 750 apparatus equipped with a thermal conductivity detector and a Porapak Q packed column. 

Larger scale chromatography was run on a J.Y. Chromatospac Prep 100 (J.Y. Instruments) or a Waters Prep-500A equipped with a Whatman Magnum 40 (4.8 X 50 cm) column dry packed with Whatman Partisil Prep 40 ODS-3 (37-60 urn) and mounted in place of the radial compression chambers. Injections were carried out by pumping on dilute solutions of samples in a solvent of lower eluting power. Detection was by the Gow Mac model 80-850 U.V. detector at 210 or 254 nm. 

During the field studies a simpler isothermal Gow-Mac gas chromatograph equipped with a hydrogen flame ionization detector was used. A 12-rt X i-in. column packed with 5% OV-17 substrate on Chromosorb W-HP was used for separation at 80 °C and 20 mL/min flow of carrier gas. 

Manufacturers or suppliers of silica-based packings for SEC are Beckman (UltraSi ierogel), ffio-Raid (Bio-Sil SEC), Mac-Mod (Zorbax PSM and GF), Merck (Lkhrospher), Syncbrom (SynChropak GPQ, Showa Denko (Protein KW), Tosoh (TSKgel SW), and Waters (Protein-Pak). 

Mackowiak (73a, 736) derived a new flood correlation. Like the Billet and Schultes correlation, it is based on the drop entrainment model and takes liquid holdup into account. Unlike Billet and Schultes, Mac wiak uses a different set of premises and e q>re8sion8. Madio-wiak 8 correlation applies for both random and structured paddngs, has a good theoretic basis and was shown (73a, 736) to predict a laige number of flood data to within 8 percent. On the debit side, the correlation Is complex and requires the availability of four constants for each packing. Ma owiak also states (73a) that for high liquid rates, Mersmann s film model is more suitable than his drop model. 

Pyrolysis gas chromatograms (PGC) were obtained on a model AIOOC Wilkens Aerograph gas chromatograph equipped with a Leeds and Northrup Speedomax G Recorder. The copper chromatography column was packed with acid washed chromosorb W and 20% SE-20. Pyrolysis was accomplished by placing a small, dry sample of polymer on a Rh-W, code 13-002, Gow-Mac coil and pyrolyzing for a predetermined time. 

You need to adjust your gas chromatograph to the proper conditions for the analysis. We recommend that you prepare and analyze the reference mixture listed in the Procedure section. Most chromatographs will be able to separate this mixture cleanly with the possible exception of the xylenes. One possible set of conditions for a Gow-Mac model 69-350 chromatograph is the following coliunn temperature, 110-115°C injection port temperature, 110-115°C carrier gas flow rate, 40-50 mL/min column length, approximately 12 ft. The column should be packed with a nonpolar stationary phase similar to silicone oil (SE-30) on Chromosorb W or with some other stationary phase that separates components principally according to boiling point. 

Reagents and Equipment The procedure involves injecting a 25-gL mixture of heptanal-cyclohexanol 1 1 (v/v) into a -in. x 8-ft stainless-steel column packed with 10% Carbowax 80/100 20M PAW-DMS. Experimental conditions (GOW-MAC series No. 350) are He flow rafe, 50 mL/min chart speed, 1 cm/min oven temperature, 155 °C. 

Fig. 105. Gas-liquid chromatogram of chlorination of germanite ore with CC1 (6 min, 575°C). Chromatographic conditions glass column length = 183 cm, o.d. =6 mm, i.d. = 4 mm. Packing material silicon oil DC 550 20% w/w on celite 545, Carrier gas flow rate 14 ml/min N2 Detector TCD (Gow-Mac 4 tungsten filaments), bridge current 150 mA. Temperatures C capsule chamber, 120 inj. port, 110 column, 80 detector, 100.

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