Dry purge

Fig. 9.4b Transient of a three kilowatt SOFC system undergoing a simultaneous loss of fuel and removal of load (emergency stop). Data points are shown at 1-minute intervals. The higher potential achieved here versus that in Figure 9.4a at zero load results from the relatively dry purge gas used. The slightly negative current shown here at zero load is due to a small DC-bias in the experimental...

Most of the other polymers show only limited thermal stability, so it is recommended that they be cleaned by solvent extraction and dry purging with pure nitrogen. 

The use of hydrophobic adsorbents combined with a dry-purge step in which loosely bound water is removed from the adsorbent trap92... 

Figure 13 is a schematic flow diagram for a two column Skarstrom type [36] PSA drier. The process can be used to obtain very dry product gas (< —60 C dew point). The product purity depends on the type of alumina used, feed gas pressure and dry purge gas quantity. Typically a practical PSA drier uses 15-30% of product gas as purge. The typical total cycle time for a PSA process is 2-4 minutes. 

Set the following parameters if the FID detector is used purge with He for 10 minutes flow rate, 40 mL/min trap rest 35 °C dry purge for 2 minutes trap desorb at 250 °C for 2 minutes and bake at 275 C for 4 minutes. 

A Dupont 990/910 DSC cell base was used for studies of cure kinetics. Gel coat sample sizes were limited to between four and six milligrams. Changes in sample enthalpies were recorded as a function of time at a heating rate of 5°C per minute under a dry purge (0.1 std. ft /hr.). Samples were scanned from room temperature to 175 C, cooled, and rerun from approximately -80 C through 200 C. 

After dry purge, the purge gas flow is stopped. The trap is heated to 5°C below the desorb temperature without gas flow. Preheat makes the subsequent desorption of analytes faster and helps prevent peak tailing. 

Dry purge n. In extrusion, preparatory to shutting down operation after the feed hopper has been emptied, running the extruder until no more plastic emerges from the head end. 

FIGURE 11.11. Adiabatic desorption equilibrium curves for (a) 4A sieve and (6) silica gel. Curves arc calculated for a uniformly saturated bed at 25 C at the indicated humidity, assuming bone-dry purge gas at the specified temperature. The 25 isotherm is shown as---------, representa-... 

It is always advisable to adhere closely to the manufacturer s instructions, especially in regard to the use of a dry purge gas. Failure to do this will result in data dominated by the spectrum of water vapor. Photoacoustic measurements are based on thermal processes, which are intrinsically slow, and in order to maximize sensitivity, slow interferometer scan rates are recommended for best performance. Note that the sample size is normally limited to a few millimeters. Always docmnent the purge gas that is used and the scan speed of the instrument because these impact the intensity and quality of the final spectrum. 

Trap Adsorbents Trapping What Purging Dry Dry Purge Time Desorb Preheat Temp. Desorb Temp. Bake Temp. Bake Time Cond. Temp, and Time Common Problems with Trap... 

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