Process for the production of sulphite liquor

Oct. 6, 1931.
M. G. T. SCHROEDER
4
PROCESS FOR THE PRODUCTION OF SULPHITE LIQUOR
Filed Feb. 29, 1928
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1,826,028
Patented Oct. 6, 1931
sire STATES;
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IYIA-X GEORG- THEODOR SCHBOEDER, 0F BER-‘LIN, GEB-IJZAI‘IY
PROCESS FOR THE PRODUCTION OF SULPHI'EE LEQUOR
Application ?led February 29, 1928, Serial No. 258,118, and in Germany August 16, 1%2'7.
My invention refers to the production of are not caused to act directly on the carbon
waste sulphite liquor and more especially to ates, but that at ?rst a watery solution of sul
'means whereby in this production pure car— phur dioxide is prepared, the percentage of
bon dioxide can be recovered as a by-product.
which sut?ces for furnishing after dissolu
Hitherto sulphite liquor for use in the tion of lime stone or other carbonates in this Cir
treatment of cellulose is produced in such solution under development of carbonic acid
manner that the gases of combustion of sul a sulphite liquor of sutlicient strength or at
phur or burner gases, being products of cal least a liquor which is strong enough to allow
cination of pyrit s, after having been cooled being subsequently brought to the required
down, are conducted through towers in coun percentage of $02 by the sulphur dioxide gas
' it
tercurrent- to water trickling down in these escaping from the boilers.
Inasmuch as the sulphite liquors for the
towers, which are moreover ?lled with pieces
of lime stone or dolomite. The towers have treatment of cellulose must have a total con
also been replaced by troughs. Now in view tent of d to 5 per cent of sulphur dioxide, and
1"‘ of the fact that the burner gases only con as he carbon dioxide gas on being developed
tain about 8 to 10 per cent per volume $03, still carries away a considerable percentage
the gases of combustion of sulphur not more of S02, the manufacture of full-grade sul
than 15 to 18 per cent, and that in producing phite liquors requires a watery solution con
, the ovor~acid sulphite liquors, 3 volumes sul~ taining about 5 to 6 per cent sulphur dioxide.
3" phur dioxide correspond to only 1 volume Now this percentage cannot be obtained by
"arbon dioxide produced, the contents of car simply absorbing the burner or sulphur coin
bonic acid in the waste gases is so low as not bustion gases in water. For obtaining a solu
to allow a commercial extraction. Therefore tion having such a high percentage of sul
_ the large quantity of carbonic acid, which phur dioxide, either the gases must be ab
might be recovered in pure state as a cheap sorbed under pressi re or SO2 must ?rst be
by-product in the manufacture of sulplii‘te produced in any suitable manner and the gas
liquor, is lost altogether. In those cases, must then be caused to be absorbed in water.
The pressure to be used for the absorption
where the carbonic acid is extracted from the
gas mixture by absorption in water under in order to obtain a sufficiently strong solu
5 high pressure, the use of carbonic acid con tion is inversely proportional to the contents
tained in lime kiln gases, which contain about oil SOg in the gases to be operated upon and
30 per cent per volume 002, is far more pref to the temperature of the absorption water.
erable.
,
It is the lower, the higher the S92 contents
In order to recover carbonic acid in the of the gases and the lower the temperature of
sulphite liquor production in a commercial the water. lVhen operating with gases of
manner, the process must berso conducted combustion of sulphur rich in S0: and with
that the carbon dioxide is not separated ‘from cold water, a pressure of 2 to 3 atins. will
40
the exhaust gases, but the sulphur dioxide sultice, while with burner gases of pyrites
must already be separated from the other about 1i to 5 atms. are required.
In compensation for this expenditure in
gases accompanying same in the beginning
of the operations. Inasmuch as the solubil energy not only the sulphite liquor produc—
such is greatly simplified, but also a
ity of sulphur dioxide in water is more than tion
40 times greater than that of carbon dioxide carbon dioxide substantially free from other
the absorption of sulphur dioxide and sepa gases is obtained. Instead of the very high
ration i’rom the other gases only requires a lime stone towers at present in use the pro
little part of the expenditure which would duction of sulphite liquor according to the
be required ‘for the separation of carbon di present invention only requires very simple
oxide. Therefore the new method based on and. comparatively small apparatus, ,u'ih as
r , these facts is distinguished from the methods illustrated diagrammatically by way of ex
Mo
U ' hitherto used in that the gases containing S02 ample in the drawing, this apparatus being
2
1,826,028
adapted for use in carrying out a continuous er consumption can be limited to a minimum,
for the pressure of the exhaust gases is uti
Referring to the drawing, l 1 and A; are lized again for the compression, n'iore, espe
two iron reservoirs, the inner walls of which cially, it these gases are reh rated before ex
are covered with lead, and o, and GJ are man panding in the engine, for instance by the 70
holes for ?llingr in pieces of lime stone, which heat of the sulphur burners or by some, other
rest on the perforated double bottoms 7L; and exhaust heat, which is a 'ailablc tree of cost.
operation.
7:2. (11, (I: are pipes provided with valves,
\Vhen manutzurturing a sulphitc liquor
through which the solution of SO: from the, such as required for use and having a con
absorption under pressure 'ran be admitted tent of‘ lime between 1 and 1.2 per cent about 75
either in the reservoir A‘ or reservoir A2. 7 to S kgs. pure carbon dioxide can be re.
Pipes 0,’ and c: serve for <‘lraining the reser
covered as a by-product per cubic meter oi’
voirs and for coiulucting thy finished liquor liquor. This carbon dioxide can either be
.
to the tanks such as l‘.
i
(ln the solution of utilized for special purposes, ‘For instance for
16
sulphur dioxide entering a reser'ioir, a vigor
25
paratively small absorben which has to pro
Various changes may be made in the de
vide room only ‘tor l/Qtlth to l/é-ltlth of the tails disclosed in the foregoing specification
gas volume which had hitherto to be accom without departing from the invention or.
modated in the absorption towers may either sacri?cing the advantages thereof.
be tilled with pieces of lime stone or, it it is
1' claim :~-90
30
desired to avoid the retillingr, with colic or
some acid~proot material. ‘Water
sup
plied to the absorber B by means of the
sprinkler pipe r/ and all the sulphur di '
is here extracted ‘from the carbon (ll( xirle egas.
a precipitation of bicarbonate in the manu- 80
ous i'levelopiuent of carbon dioxide gas will tacture of soda according to the ammonia
take place, this gas being carried throug proce:~:s, which does not require any energy
pipes f, or f; to an absorber B which serves and does not i'urnish : ny exhaust gases, or it
for absorbing any 5th, vhich may be 'ar~ can be lique?ed or solidified by compression
85
20 ried away by the tarbon dioxide. This com and can be sold in this condition.
l. The method oi’ producing~ sulphite lili
uor and pure carbon dioxide comprising ex
tracting a gas containing sulphur dioxide
with water under pressure for the recovery
o‘l" Ht), from said gas, acting with the S0,,
The pure ‘arbou dioxide (‘817215195 through solution thus obtained on a decomposable ar
pipe h into a '\ ‘amber in, tilled with a solution bouate and collecting the carbon dioxide gas.
of bicarbonate, escapingr l’ixn the washer
through pipe 0 into a
someter p.
In order to produce the carbon dioxide in
an uninterrupted stream, the preparation of
the sulphite liquor is carried out in the reser
voirs A, and A: alternately. lvhile one of
the reservoirs is in operation, sulphite liquor
40
45
The method of producing sulphite liq
uor and pure 'arbon dioxide comprising ex
tracting! a gas containing sulphur dioxide 100
with water under pressure "for the recovery
of SO: from said gas, acting‘ with. the SO:
solution thus' obtained on a decomposable
carbonate, collecting the *arbon dioxide gas
is exhausted ‘from the other one, ‘fresh lime and washing same to remove the sulphur di- Jo;
stone being" tilled in, if l'itPt'OHL-‘Zli‘l’. 'l‘he solu— oxide still admixed to it.
tion escaping from the absorber B can be
3. The method of producing sulphite lid
conducted either to the rez-ieryoir A, or to the uo ' and carbon dioxide which comprises ah
reservoir A: as desired through pipes fl or sorbing sulphur dioxide in \ tater under pres
f,. respectively.
sure to ‘term a concentrated solution oii sul- 11o
Instead of producingr a solution oi’ sulphur phurous acid, subjectingr a decomposable car
dioxide sullicientiy strong tor the preparation bonate to the action of the l'e?lllilillg solution,
of the sulphite licpiors, I may also use pure and collecting the resultingr gaseous and liq—
St)2 gas for the production of pure carbon uid reaction products.
‘
dioxide, the 5103 being introduced into an
4. The method of producing sulphite liq~ 115
apparatus tilled with a suitable carbonate nor and carbon dioxide which comprises dis
and water or beincr <r'onducted in eountercur solving: sulphur dioxide from a mixture of
H
rent to water tric l'ufr
down a tower tilled gases with water under pressure to term a
with lime stone. To this end the sulphur comrentrated solution of sniplmrous acid, sub
dioxide must first be expelled from its watery iectinir a deerni'iposable carbonate to the ac- 125'
solution or must be prodiu'ed in pure state tion of the resulting solutioin and collecting
in some other way. Such process can be car the resulting gaseous and liquid 1' aictii n
ried through in a commercial manner only products.
where fresh or exhaust st 2am
ayailable at
In testimony whereoi’ I allix my signature.
low cost. ()n the other hand the process
MAX ozone raronoa 'scaiioanni.
12:
with solutions rich in Lit 2 and obtained di
rectly by absorption merely requires power
for compression, which
frequently avail
able in natural sources of energy without re
quiring any expenditure for coal. The pow

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