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Патент USA US2108976

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Feb. 22., 1938.
’n 2,108,976
G. P. VINCENT
PRODUCTION OF CHLORINE DIOXIDE
Filed Aug. 15, 1934
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Patented Feb. 22, 1938
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AUNITED STATES PATENT OFFICE'. '
PRODUCTION OF CHLORINE- DIOXIBE`
George Paul Vincent, Niagara. Falls, >N. Y., as- .
signor to The Mathieson Alkali Works, Inc.,
yNew York, N. Y., a corporation of )'irginia
'
a
Application August 15, 1934, serial No. 739,888
1o claims. (cies-¿152)
production
This invention
of chlorine
relates dioxide.
to improvements
More particu-v
in the the
the'> Chlorine
absorption
dioxide
medium
diluted
by -With
aeration,
al1', by.
to heating
recover
larly, the invention relates to a method for selec-
the charged absorberitmedillm Olïby 9L COmbîna-
tively separating chlorine dioxide from a'gas mlx-
tion Of 'heating and aeration.
_
~
'
5 ture including chlorine and chlorine dioxide, such ' As previously noted, while the aqueous absorp- 5
as gas mixtures produced by reaction between tion medium need be chemically inert With`re-'
chlorates and acids,
_
_. - spect to chlorine dioxide only, it is ¿preferably
According to this invention, chlorine dioxide
is separated from such gas mixtures by selective
l0 absorption of the chlorin'e dioxide in an aqueous
' medium chemically inert with respect to chlorine
dioxide. Preferably the aqueous absorption medium `is chemically inert with respect to both
chlorine dioxide and chlorine. The absorption is
chemicalli1 inert With respect to both Chlorine
dioxide end_chlorîne. The use of __such a medium
is advantageous, for example, in that the'Chlo- lo
rine may be more readily recovered, itsjrecovery
cost being much less than-in those cases Where
the chlorine reacts to any substantial extent with
l5 with advantage carried out at low temperatures,
the absorption medium.`
Aqueous media chem- _
_
lcally inert. aS that term iS used herein, vwith re- 15
between about 10°_ C. and the temperature at
spect to both chlorine dioxide and’chlorine in
Whioh the aqueous medium freezes. It may, how-
clude water, aqueous solutions or mixtures of the
ever, be carried out at higher temperatures. BY chlorides and ClllOTateS'OÍ Sodium, Calcium and
the use of the low temperatures, the volume of »magnesìum, andaqueous 'sulfuric acid, advanta
29 aqueous medium to be handled'is reduced. While geOl-lSlY 0f a cûneenti‘ation approximating ’40%- 20
the use oi’ a low temperature reduces the volume
of aqueous medium to be handled and results in
decreasing the cost of circulation and absorption, .
Whether or not a low temperature should be used
es in making the separation will depend on whether
the savings which can be effected by the use of
alow temperature will be offset by the cost of
producing the ~low temperature. In practical operation, therefore, the exact temperature to be
:zo used will depend on local conditions in regard to
96% H2SO4.
'
'
"
vIn carrying out the invention. the aqueous ab
Sorptíon medium iS With advantagel maintained
in CyClie CirCUletiOn from?. Stripping >ZOIle t0 and
through an absorption zone and back tothe strip- 25
ping Zone, the sas mixture including chlorine andv
Chlorine dioxide being COIiteCted illîth the absorp
tion medium in the absorptif‘n Z‘ ne and the ab
Sol’loeflY chlorine _di ide beim st. ipped fl‘Om the 30
absorption medium 1n the strlppin r Zone.
.
power, iuel and labor.
The aqueous media useful in carrying out the
The invention will be further illustrated by the
following examples of operations embodying the
invention
inventiom. n
include
water,
aqueous
solutions
of
salts chemically inert with respect to chlorine.v
35 dioxide or mixtures of such salts, such as the
chlorides and chlorates ofA sodium, calcium and
magnesium, and aqueous 'sulfuric acid, advantargeously of a concentration approximating 40%-'
96% HzSOi. While effective separations can be
_
Y
_
_
»
'
`
EIGmPle 1--A gas mìXtllI'e Consisting 0f ap
prOXîmately 'equal PI'OPOI'tîOnS of Chlorine and 35
chlorine dioxide diluted With‘air to an'ïextent
such that the partial pressure of the chlorine
vdioxide approximated 200 mm. of mercury (at
standard conditions) `was scrubbed with water
40 obtained using `Water as the absorption meduim, jat a temperature just above 0° C. 92% of the 40
solutions of salts chemically inert with respect chlorine dioxide originally present but only 14% '
to chlorine dioxide appear to be particularly advantageous. Effective separations can be obtained using aqueous sulfuric acid' as >the absorp45 tion medium but recovery'of the absorbed chlorine dioxide from water or salt solutions is effected with greater ease. Completeness of separation o_f _the chlorine dioxide from such gas '
l mixtures is promoted by carrying out the ab-
50 sorption .under conditions such, that the partial
of the chlorine originally present 'were absorbed
by the water, the eilluent gas mixture including
86% of the chlorine and only 8% ,of the chlorine
dioxide originally present.
45
Example 2.--"I'heA same gasv mixture was
scrubbed with 'an aqueous solution of sodium
chloride containing 26% (by weight) NaCl at a
temperature of 0° C. `_32l parts (byvweight) of
_
chlorine dioxidewerea sorbed by thesaline ab- 50
pressure of the chlorine dioxide approximates ' sorption medium forY every part of chlorine ab- Y
mercury
10-500 mm.
in of
themercury
gas mixture
or better
as supplied
50-350 mm.
to the
of
sorbed.
Example
absorption zone. Following absorption, the ab-
scrubbed with aqueous sulfuric acid containingi
55 sorbed chlorine dioxide can be recovered from
3.*-The
. same
_
Y
' gas
`
mixture
`
was
as supplied to the scrubbing operation, 76% 55
____
. 2
2,108,976
_
1. In the vproduction of chlorine dioxide,vthe
H2504 at a temperature of 3° C. 98% of the
chlorine dioxide and substantially none of the
chlorine originally present were absorbed _by the
improvement which comprises separatingchlo
_rine dioxide from a gas mixture including chlo
rine and chlorine dioxide by selective absorption
of the chlorine dioxide in aqueous sulfuric acid, 5
Example 4.-A gas mixture consisting of ' ap
proximately equal proportions of chlorine and and recovering chlorine dioxide from the absorp
absorption medium.
' 5
., y
chlorine dioxide diluted with air to an extent that
tion medium.
the partial pressure of. the chlorine dioxidel ap
,fproximated 35mm. of mercury (at standard con
improvement which comprises separating chlo
sodium chlorldecontainlng 26% (by weight) NaCl
, rine and chlorine dioxide by selective absorption
ain the production of chlorine dioxide, the `
10 ditions) was scrubbed with an aqueous solution oi - rine dioxide from> a gas mixture including chlo
`of the chlorine dioxide in aqueous sulfuric acid
at a temperature of 24° C. The aqueous solution
of'sodium chloride containing absorbed chlorine@ at a temperature below about 10° C., and recover
dioxide was subjected to aeration yand chlorine ing chlorine dioxide from the absorption medium. '
3._In the 'production of chlorine dioxide, the 15
v15 dioxide 93.9% pure with'v respect to chlorine
obtainecb Ii the gas mixture be cooled to about" improvement'` which comprises separating chlo
¿_
"\
rine dioxide `from a gas mixture including chlo
3° C. before scrubbing with the laqueous salt solu'
tion and the resultant solution be heated, `by
means of steamor hot water, for example, to a
20 _temperature of 50°C. or 60° C. immediately prior
to the strippingoperation a greater yield of. chlo-`
rine and chlorine _dioxide by selective absorption
of the chlorine dioxide in an aqueous solution
containing' a chloride and a chlorate of one or 20
more elements of the group consisting of sodium,
rine dioxide per unit of timecan be obtainedthan calcium and magnesium, and recovering chlorine
Awhere the operation is conducted as above.
1 dioxide from the absorption solution. 1
4. InV the production of chlorine dioxide, the
25 grammatically and conventionally, forms of ap--- improvement which comprises separating tchlo-v
rine dioxidefrom a gas mixture including chlo
_paratus appropriate for lcarrying out the inven
'The accompanying drawing illustrates, dia
rine and chlorine dioxide by selective absorption
tion. The apparatus illustrated in Figure 1 pro
videsfor recovery of absorbed chlorine. dioxide
of the chlorine _dioxide in an aqueous solution ’
containing a chloride of an element ofthe group
30 apparatusillustrated in Figure 2 providesfor. consisting of sodium, ,calcium andv magnesium,
recovery of the absorbed .chlorine dioxide b_y a 'and recovering chlorine dioxide _from the absorp
combination of heating and aeration of the-ab
5. In the production oi chlorine dioxide. the ‘
sorption medium.'
'
`
. by aeration of the absorption mediumand the ~
Referring to Figure 1; the tower 3 isthe -ab- - improvement which comprises separating chlorine
35 vsorption zone and the tower A4 is -the stripping dioxide from a gas ' mixture including chlorine 35
zone.
'I'hese two towers'xnay be of any conven
„tial type' promoting gas and liquid contact, for
and chlorine dioxideby selective absorption'of
the chlorine dioxide in an aqueous solution' con
,example they Ymay be packed Awith distributing ,. tainingachlorate of an element of the group con
Yelements or they may be of so-called ."bubble’.’ .sisting of` sodium, calciumgand magnesium, and I
40 tower construction. The stripped absorption recovering chlorine dioxide from the absorption
medium _from Vtower 4 is supplied to tower 3. solution. .
k Y A, _ through connections I and 6 by means of pump 1.
'I'he gas‘mixture, including chlorine >and chlorine
4dioxide and diluting air for example, is supplied
` to tower 3 through- connection 8.' ’I'he gasvmix
50
ture'remaining after absorption Yot chlorine dl
oxide _in tower 3 is discharged throughy connection- 9. The absorption medium vcharged with
absorbed chlorine dioxide is conveyed from tower
3 to tower 4 through connection I 0. In tower 4
the >charged absorption medium is stripped of
absorbed chlorine dioxide by air supplied through
connection II. The recovered chlorine dioxide,
i» s » in a mixture with the'air supplied for aeration, is
__ 55 discharged fromtow'er 4 through connection I2.
' Referring to Figure 2,' the same or correspond
afin the' production of ohiorine dioxide, ooeA ,
improvement which comprises separatingchlo
rine dioxide from a gas mixture including chlo
» rine and chlorine dioxide by selective absorption
ofthe chlorine dioxide in anaqueous' solution
454
f containing a chloride and a c_hlor'ate of one o_r
more elements of the group consisting of sodium,
calcium> and magnesium ata temperature below
about 10° C., and recovering chlorine dioxide
from the absorption solution. I'
'7. In the production of chlorine dioxide, the -
improvement which comprises separating ~chlo
rine dioxide from a -gas mixturexî-including chlo
rine and chlorine dioxide by'selective absorption 55
of the chlorine dioxideinf an ¿aqueous solutionV
` ' ing parts ‘are designated by the sameîreference. `containing a chloride of an element of the group
charactersv used in Figure 1 withv the letter “a”
consisting of sodium, calciuinand magnesium at
appended. iThe stripped absorption medium sup- . a temperature below about l0"v C., and recovering ' '
50 plied from. the tower 4a to the tower 3a by means . chlorine dioxide from the absorption solution. '
8. In'the production of chlorine dioxide, the
of pump ‘Iais cooled, before entering the tower
improvement whichv comprises separating chlo
3a, by passage successively through the heat ex
changers I3 and I4.> The absorption medium rine dioxide from a gas mixture including chlo
charged with chlorine dioxide flowing from tower rine and chlorine dioxideby selective absorption
y
"so
3a to tower4a is heatedv by passage Asuccessively Y of the chlorine dioxide in an aqueoussolution con 65
through the heat exchangers `4I3 and I5. In the taining a chlorate of an element of the group con
heat exchanger I3 _ the charged 'absorption sisting of sodium, calcium and magnesium at a
medium is heated and the'stripped absorption
medium »is cooled by heat exchange between the
70 two. A refrigerating'medium, chilled brine for
temperature below about 10° C., and recovering
chlorine dioxide froml the absorption solution.
_ 9. In the production oi chlorine dioxide,ïthe“
example, is supplied to heat exchanger I4 through . improvement which comprises separating chlo
connection I6 and a heating medium, steam for . rine dioxide from a gas mixture including chlo
example, is ,_ supplied to heat exchanger I5 rineand chlorine dioxide by selective absorption
through connection -I 1.
'
of the Vchlorine dioxide in an aqueous solution of
75 Iclaim:
4‘
,a salt of one or more elements of the group con
2,108,676
sisting of sodium, calcium and magnesium, which
salt is chemically inert with respect to chlorine
dioxide and chlorine, and recovering chlorine di
oxide from the absorption solution.
l0. In the production of chlorine dioxide, the
improvement which comprises separating chlo
rine dioxide from a gas mixture including chlo
rine and chlorine dioxide by selective absorption
3
of the chlorine dioxide in an aqueous solution
containing a material chemically inert with re
spcct to chlorine and chlorine dioxide of the class
consisting of sulphuric acid and salts of the
' _elements of the group consisting of'sodium, cal- ì
cium and magnesium, and recovering chlorine di
oxide from the absorption solution.
GEORGE PAUL-VINCENT..
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