chemical physics of discharges - Argonne National Laboratory

On the other hand, if hydrazine is formed and degraded
ullifolvly in the activating section of tlie discharge this
result is difficult to explain. It is suggested from this
that,under these conditions, the absorption process is no
lolyer the controlling factor since an increase in, the
overall potential absorption rate,tiirou(jh an increase in the
illterfacial area ,produces no corresponaing rise in Warazine
yields. I~ mag be that liquid surface activation phenomena
are t*&ing place and the increased hydrazine yield which is
observed with the use of an absorbent liquid is caused by
hydrazine formed by otlier mechanisms in which the liquid
surface plays an important role. If this were the case the
liquid film, wnich presents a complete barrier to the discharge,
would naturally give naximal yield and tile spray reactor
would only tend to tllis value in tile limit.
It was found experimentally that a decrease in the
residence time of the recictant in the discharge is accompanied
by an increase in energy yield of ivarazine and a corresponding
fall in percent%e conversion. . The results are detailed in
Blg.5 and appear to be in general agreement with those of
kchi (6). When a liquid,absorbent is used the change of
yield and percent conversion is steady but without the use of
an Crbs'orbent the effect becoines very marked at low residence
times. Ouchi (6) has concluded from his results that soae of
the. hyQatinO formed in the diecharge is preserved from
degradation by rapid physical removal out of the discharge.
This would adequately explain, in general terms, the increase
in energy yield with reduced residence time. The degree of
activation of species in the discharge uust fall as the
reactaqt throughput is increased. This would result in a
decrease in percent conversion as residence time was reduced.
Furthermore, as the concentration of hydrazine governs the
rate of the degrading reaction t!ie smaller. percent conversion
achieved at high flow rates will result in a.higher overall
energy yield being achieved. With the use of a liquid
absorbent soize effect on tile yield may well arise beczuse
of changes in the absorbtion rates due to i;.;creased turbulence
and a decrease in the gas liquid cmtact time.
Another point which .mst be borne in mind is that physical
removal of the product or even,for trlat matter, the use of
the pulsed uischarge tec'mique cannot give better convers,ions
,than that dictated by tne equilibrium concentration of
hydrazine for tne basic reactions t?-king place in the discharge.
Tie use of the liquid absorbent, on the other hand, permits
nigner conversion to be achieved because of tile inability of
tne uiscliarge reackion to reach equilibriun as ludraziae is
being continuously renov4 after it is formed in tile discharge.
The negative sloDe of tne ener$y yield-residence the
plot (Pig. 5), yhen liquid absorbent was used, implies that it is
oossible to increase yields Still furtlier by so:ue otiier
suitable LnoGification of technique.. .
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