Патент USA US2108976код для вставки
Feb. 22., 1938. ’n 2,108,976 G. P. VINCENT PRODUCTION OF CHLORINE DIOXIDE Filed Aug. 15, 1934 ÈtâûÈcqë e @W ,È yv e „mm JA.l?my,‘mEm m 6. o e E f n w n Patented Feb. 22, 1938 y Y l I _ . l 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..