Counter purge

When the dryer is seen as a heat exchanger, the obvious perspective is to cut down on the enthalpy of the air purged with the evaporated water. Minimum enthalpy is achieved by using the minimum amount of air and cooling as low as possible. A simple heat balance shows that for a given heat input, minimum air means a high inlet temperature. However, this often presents problems with heat-sensitive material and sometimes with materials of constmction, heat source, or other process needs. AH can be countered somewhat by exhaust-air recirculation. 

In these gas-flow proportional counters, the windows are exceedingly thin, fragile,. and unavoidably leaky. Such a window is satisfactory only if a steady flow of. the filling gas is maintained at minimum pressure differential against the helium atmosphere in the optical path. The purging of impurities from the counter is an incidental benefit derived from the gas flow. Hendee, Fine, and Brown20 look upon the gas-flow proportional counter as a steppingstone on the road toward a windowless counter. 

A schematic representation of the lower half of an EQCM cell is shown in Figure 2.109. The crystal is clipped or glued to the bottom of the electrochemical cell. Within the cell are the reference and counter electrodes, and a purging device to allow N2-saturation of the electrolyte. 

After the third extraction, we measure the radon and its yield by adding several cc STP of carrier Ar to the melt water with He to 1.3-atm pressure and allow the radon to build up for 4 days. We also replace the spiral glass C02 trap with a charcoal trap to insure the collection of the carrier Ar with the radon. We then He-purge the water and collect the Rn with the carrier Ar on the charcoal at liquid air temperature. The Ar plus Rn is recovered from the charcoal at 300 °C purified over hot Ti and counted in a proportional counter. 

The outlet of the supply point is opened and purged for 5 min. Adjust to a volume flow of about 30 1/min. The particle counter is connected to the outlet at the maintained flow a minimum volume of 90 liters is monitored. Each supply point should be investigated in the same way. 

Anthraquinone glycosides are coloured substances, and are the active components in a number of crude drugs, especially with laxative and purgative properties. Anthraquinone aglycone increases peristaltic action of large intestine. A number of over the counter laxative preparations contain anthraquinone glycosides. The use of anthraquinone drugs, however,... 

The cell consists typically of a 10-20 mL vessel and an electrode holder made of plastic or Teflon with holes for the working (W), reference (R) and counter (C) electrodes. In addition, there is an inlet for an inert gas, usually nitrogen or argon, by which the solution is purged before the measurements are made. Usually also, a gentle stream of the inert gas is maintained over the surface of the solution during the electroanalytical measurements. 

The effect of feed composition on enrichment at maximum recovery is shown in Table 2. Both high enrichment and good recovery are obtainable with the leaner feed composition, a result tfiich is counter to intuition. The explanation lies in the fact that light gas losses in the purge and blowdown gas decrease as the feed becomes leaner in the light gas. 

Zikovsky, L. and N. Roireau. 1990. Determination of radon in water by argon purging and alpha counting with a proportional counter. Appl. Radiat. Isot. 41 679-681. 

Fig. 15.25. Schematic for a laboratory-scale packed-bed electrode, a, Bed of particles b, current collector c, Luggin capillary d, thermometer e, purging gas in f, gas out g, bubbler h, gas collector i, Luggin capillary j, reference electrode k, Nation film I, counter-electrode m, septum for gas analysis and n, solution flow-in or flow-out. (Reprinted from J, O M. Bockris and J. Kim, J. Appl. Electrochem. 27 625, copyright 1997.)...

For some samples, the gas was allowed to decay for two half-lives, the residual gas removed by purging with a hot air stream, and the remaining short-lived daughter activities observed. The time required for handling, separation and transport to the counter for regular gas samples was 20-30 seconds. ... 

Fig. 13. Vh20, measured in aq. saturated or molten NaOH, at 1 atm.90 CO2 is excluded by argon purge. The molten electrolyte is prepared from heated, solid NaOH with steam injection. O2 anode is 0.6-cm2 Pt foil. IR and polarization losses are minimized by sandwiching 5 mm from each side of the anode, two interconnected Pt gauze (200 mesh, 50 cm2 = 5 cm x 5 cm x 2 sides) cathodes. Inset At 25 °C, 3 electrode values at 5 mV/s versus Ag/AgCl, with either 0.6-cm2 Pt or Ni foil, and again separated 5 mm from two 50-cm2 Pt gauze acting as counter electrodes.

The ZLC method offers advantages of speed and simplicity and requires only a very small adsorbent sample thus making it useful for characterization of new materials. The basic experiment using an inert carrier (usually He) measures the limiting transport difiiisivity (Do) at low concentration. A variant of the technique using isotopically labeled tracers (TZLC) yields the tracer diffiisivity and counter diffusion in a binary system may also be studied by this method. To obtain reliable results a number of preliminary experiments are needed, e.g. varying sample quality, nature of the purge gas, the flow rate and, if possible, particle size to confirm intracrystalline diffusion control. 

Psia, (b) co-current CO2 rinse at that pressure with recycle of effluent gas as feed, (c) counter-current evacuation to - 2.5 Psia with simultaneous steam pui e, and (d) counter-current pressurization with a part of CO2 depleted product gas from step (a). The effluent gas from step (c) is partly used as the purge gas in step (b) after recompression, and the balance is withdrawn as the recovered CO2 product gas. The inert gas and CO2 recoveries from the feed gas are, respectively, - 100 and 78% [21]. This application may be attractive for green house gas emission control (CO2 sequestration from a hot flue gas or CO2 removal from combustion gases for power generation). 

Figure 1 Flowsheet of hybrid membrane-PSA process. Steps pressurization (PR = PRi + PR2). high-pressure adsorption (HPA), co- and counter-current blowdown (CD, BD), Purge (PG) A stream enriched in less adsorbed component, B-. stream enriched in strongly adsorbed component. Pressure histories of the integrated cycle at CSS.

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