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Burnoff

Figure 9. Effect of burnoff on surface oxygen content natural graphite NG7 [391. Figure 9. Effect of burnoff on surface oxygen content natural graphite NG7 [391.
The oxygen peak maximum shifted monotonically with burnoff time, rising from 531.05 eV for pristine NG7 to 534.0... [Pg.438]

The writers have found in their laboratory that invariably after a certain burnoff (depending upon the reactor, temperature, and sample), a subsequent extended period of constant reaction rate, expressed in grams of carbon reacting per unit time, is attained. In this bumoff region, there obviously is equilibrium between the rate of formation of the surface-oxygen complex and its removal with a carbon atom. It is felt that this is the reaction rate most characteristic of a given temperature and should be used in kinetic calculations. In principle, Wicke (31) concurs with this reasoning and reports reactivity data only after the sample has attained a total surface area which is virtually constant. [Pg.161]

Experimental evidence, presented in Sec. VI and elsewhere 31,106), suggests that after a relatively small burnoff ca. 5%) the surface area available for reaction and the over-all reaction rate remains virtually constant over a... [Pg.167]

The most accurate way to obtain the rate of reaction at any radius in the rod would be to react a series of identical rods under identical conditions to different burnoffs, followed by the cutting of each rod as described. The... [Pg.179]

Fig. 11. Plot of weight loss vs. time for reaction of spectroscopic carbon rod with carbon dioxide at 1305° (Zone II) to 11% burnoff. Fig. 11. Plot of weight loss vs. time for reaction of spectroscopic carbon rod with carbon dioxide at 1305° (Zone II) to 11% burnoff.
At temperatures below Zone II, equilibrium burning (as illustrated in Fig. 10) obviously is not obtained. It is found, however, that after some bumoff (usually less than 5 %) the reaction rate is essentially constant over a wide burnoff range. A typical reactivity plot is shown in Fig. 12. If it is assumed that the porosity measured at the close of the run is derived from uniform burning over time Af, then... [Pg.182]

Fio. 13. Porosity profiles through spectroscopic carbon rods before and after ca. 11% burnoff at different temperatures. [Pg.184]

The reaction is carried out at a bed temperature of 400-500 °C and a gas contact time of 1-15 s [76] or 5-20 s [2]. Figure 17 is a schematic of the reactor. Air is fed to the bottom of the fluidized-bed vessel. The reactants ammonia and propene are fed in through a separate distributor (b). Catalyst regeneration by carbon burnoff occurs in the space between the air distributor and the feed-gas distributor. The heat of reaction is removed by bundles of vertical tubes (a) inside the bed (horizontal tubes are used in other designs [77]). [Pg.462]

Air oxidations of the 1273 K chars were performed over the temperature range of 773 K to 873 K at atmospheric pressure. In these experiments, two grams of char were placed in a quartz tube reactor held vertically in a fluidized bed sandbath. Preheated air, at a flow rate of 1.7 1/m, was passed upward through the sample. The char was oxidized to the desired burnoff and the residual char was examined to determine changes in the concentration of C, H, and N as a... [Pg.302]

Figure 1. Retention of Acridine Char Nitrogen as a Function of Burnoff in Air at 773 K... Figure 1. Retention of Acridine Char Nitrogen as a Function of Burnoff in Air at 773 K...
Char nitrogen enrichment which occurs at low burnoff at 773 K, has been observed during the partial combustion of shale particles (4). The results at 798 and 823 K are in agreement with the results of Song 05) for the oxidation of a 1750 K lignite char at 1250 K. It appears that the rates of oxidation of char carbon and nitrogen are equal at the temperatures of interest in practical combustors. [Pg.306]

Acridine char nitrogen, retention as function of burnoff, 307/, 308/ Advection fluxes, calculation, 41-43 Aerosol particle size distribution, molecular clusters, 317 Aerosol scavenging pathway, acetic and formic acid formation, 223 Aerosol species, transformation over the western Atlantic, 52 Aerosol sulfate airborne determination, 298 See also Sulfate... [Pg.322]


See other pages where Burnoff is mentioned: [Pg.437]    [Pg.437]    [Pg.438]    [Pg.438]    [Pg.429]    [Pg.63]    [Pg.161]    [Pg.161]    [Pg.168]    [Pg.180]    [Pg.188]    [Pg.188]    [Pg.189]    [Pg.189]    [Pg.315]    [Pg.289]    [Pg.301]    [Pg.303]    [Pg.303]    [Pg.306]    [Pg.308]    [Pg.309]    [Pg.312]    [Pg.312]    [Pg.1373]    [Pg.297]    [Pg.299]    [Pg.1250]    [Pg.1255]   
See also in sourсe #XX -- [ Pg.5 , Pg.39 , Pg.40 , Pg.44 ]




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Carbon burnoff

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