EP2675752A1 - Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore - Google Patents

Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore

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Publication number
EP2675752A1
EP2675752A1 EP12705829.5A EP12705829A EP2675752A1 EP 2675752 A1 EP2675752 A1 EP 2675752A1 EP 12705829 A EP12705829 A EP 12705829A EP 2675752 A1 EP2675752 A1 EP 2675752A1
Authority
EP
European Patent Office
Prior art keywords
stream
chlorine
hydrogen chloride
column
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12705829.5A
Other languages
German (de)
English (en)
Inventor
Hans-Jürgen PALLASCH
Heiner Schelling
Peter Van Den Abeel
Till EINIG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Priority to EP12705829.5A priority Critical patent/EP2675752A1/fr
Publication of EP2675752A1 publication Critical patent/EP2675752A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C01B7/0743—Purification ; Separation of gaseous or dissolved chlorine
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/03—Preparation from chlorides
    • C01B7/04—Preparation of chlorine from hydrogen chloride
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C01B7/075—Purification ; Separation of liquid chlorine

Definitions

  • the invention relates to a distillation process for the separation of chlorine from a gas stream containing oxygen and chlorine and to a process for the production of chlorine from hydrogen chloride comprising this distillation process.
  • chlorine or chlorine sequential products such as phosgene are used
  • the by-produced hydrogen chloride can be converted back into chlorine by electrolysis or by oxidation with oxygen. The chlorine thus produced can then be used again.
  • EP-A 0 765 838 discloses a process for working up the reaction gas formed from hydrogen chloride, hydrogen chloride, oxygen and water vapor in the hydrogen chloride oxidation, in which the reaction gas leaving the oxidation reactor is cooled to such an extent that water of reaction and hydrogen chloride in the form of concentrated hydrochloric acid condense, the concentrated hydrochloric acid is separated from the reaction gas and discharged, the remaining, essentially freed of water and a portion of the hydrogen chloride reaction gas is dried, the dried reaction gas of chlorine, oxygen and hydrogen chloride compressed to 1 to 30 bar and cooled the compressed reaction gas and is liquefied for the most part, wherein non-condensable components of the reaction gas are at least partially recycled to the oxidation reactor.
  • the dried and compressed reaction gas mixture is liquefied in a so-called chlorine recuperator designed as an expansion cooler, except for a residual proportion of about 10 to 20%.
  • the separated in the chlorine recuperator liquid main stream of chlorine is then cleaned in a distillation column, in which the chlorine is freed of residual dissolved hydrogen chloride, oxygen and inert gases.
  • the withdrawn at the top of the distillation column, consisting essentially of hydrogen chloride, chlorine, oxygen and inert gases gas is returned to the compression stage.
  • the non-condensed at the chlorine recuperator gas components including the residual chlorine content are partially liquefied in a post-cooling stage at a significantly lower temperature.
  • the remaining waste gas from unreacted hydrogen chloride, oxygen and inert gases is recycled to the oxidation reactor. A portion of the recycled gas is separated as a purge gas stream and discharged from the process to prevent accumulation of impurities.
  • WO07134716 and WO07085476 describe the beneficial effect of the presence of HCl in chlorine separation.
  • the condensation stage for water and HCl is operated so that a beneficial amount of hydrogen chloride with the process gas passes through the drying stage in the compressor and the subsequent chlorine separation.
  • a portion of the gaseous hydrogen chloride is taken from the feed stream to the process and fed directly into the chlorine separation, bypassing the other process stages.
  • WO 07085476 describes a process for preparing chlorine from hydrogen chloride by the steps of a) feeding a hydrogen chloride-containing stream a1 and an oxygen-containing stream a2 into an oxidation zone and catalytic oxidation of hydrogen chloride to chlorine, wherein a product gas stream a3 containing chlorine, water, oxygen, Carbon dioxide and inert gases is obtained; b) contacting the product gas stream a3 in a phase contact apparatus with aqueous hydrochloric acid I and partially separating water and hydrogen chloride from the stream a3, wherein a gas stream b containing hydrogen chloride, chlorine, water, oxygen, carbon dioxide and optionally inert gases remains, wherein at least 5 % of the hydrogen chloride contained in the stream a3 remains in the gas stream b; c) drying the gas stream b, leaving a substantially anhydrous gas stream c containing hydrogen chloride, chlorine, oxygen, carbon dioxide and optionally inert gases; d) partial liquefaction of the gas stream c by compression and
  • step d) the dried gas stream c, which consists essentially of chlorine and oxygen and also contains hydrogen chloride and inert gases (carbon dioxide, nitrogen), is compressed in multiple stages to about 10 to 40 bar.
  • the compressed gas is cooled to temperatures of about -10 to -40 ° C.
  • the compressed and partially liquefied, two-phase mixture is finally separated in a mass transfer apparatus.
  • the non-liquefied gas stream in this case in countercurrent or in co-current with the liquid, which consists essentially of chlorine and dissolved carbon dioxide, hydrogen chloride and oxygen, brought into contact.
  • the non-liquefied gases accumulate in the liquid chlorine until the thermodynamic equilibrium is reached, so that a separation of inert gases, in particular of carbon dioxide, via the exhaust gas of the subsequent chlorine distillation can be achieved.
  • the liquefied chlorine with a chlorine content of> 85 wt .-% is subjected to a distillation at about 10 to 40 bar.
  • the bottom temperature is about 30 to 1 10 ° C, see the head temperature depending on the hydrogen chloride content in the liquefied chlorine between about -5 to -8 ° C and about -25 to -30 ° C.
  • HCI reflux achieves almost complete chlorine separation, minimizing chlorine loss.
  • the chlorine taken off at the bottom of the column has a purity of> 99.5% by weight.
  • a significant disadvantage of the aforementioned method is the comparatively high energy consumption for the liquefaction of the chlorine gas stream by either very high operating pressures (15 to 40 bar) or alternatively - at lower operating pressures - very low condensation temperatures (-35 to -80 ° C).
  • the object of the invention is to provide an improved process for the separation of chlorine from a gas stream containing at least chlorine and oxygen. It is in particular an object of the invention to provide such a process for separating off chlorine from a chlorine, hydrogen chloride, oxygen, carbon dioxide and, as appropriate, if further inert gas containing gas stream in the context of a method of catalytic hydrogen chloride oxidation provide.
  • the object is achieved by a method for the separation of chlorine from a gas stream containing oxygen and chlorine I, in which the gas stream in a lower part of a column K1 and a separately provided liquid hydrogen chloride stream II are fed into an upper part of the same column and the ascending gaseous Current I is brought into contact with the descending liquid stream II, whereby gaseous chlorine condenses out of the stream I and liquid hydrogen chloride evaporates from the stream II, whereby a substantially chlorine-free gas stream III containing hydrogen chloride and oxygen and a liquid stream IV containing chlorine are obtained ,
  • a column in the context of the present invention is a multi-stage heat and mass transfer apparatus in which there is heat and mass transfer between a liquid and a gaseous phase.
  • the essentially chlorine-free gas stream III is obtained as the top draw stream and the liquid stream IV as the bottom draw stream.
  • the crude gas stream I is fed into a lower part of a column K1 and the separately provided liquid hydrogen chloride stream II in an upper part of the same column.
  • the crude gas stream I is thus fed in the column K1 below the separately provided liquid hydrogen chloride stream II.
  • the liquid hydrogen chloride stream in the upper half and the gas stream to be separated are added in the lower half of the column.
  • the liquid hydrogen chloride stream II is added at the top of the column.
  • the column K1 is operated at a pressure of 1 to 30 bar, preferably at 3 to 15 bar.
  • the temperature at the bottom of the column is -50 to +90 ° C, preferably -40 to +60 ° C, the temperature at the top of the column is -80 to +10 ° C, preferably -60 to -10 ° C.
  • liquid hydrogen chloride in the chlorine separation of the Deacon process provides the heat required for evaporation of hydrogen chloride from the process gas stream conducted into the chlorine separation and at the same time removes the heat to be dissipated in the chlorine condensation from this process gas stream.
  • This is done according to the invention by direct energy exchange by contacting the two process streams in columns.
  • an indirect energy exchange can take place via heat exchanger surfaces in heat exchangers.
  • the hydrogen chloride stream is provided separately, that is he does not fall in the distillation itself as a reflux stream. Rather, it is provided from an external source and fed at a suitable point of the distillation column in addition to the gas mixture to be separated.
  • the process streams are brought into contact in a countercurrent column having from 2 to 20 theoretical plates.
  • a countercurrent column having from 2 to 20 theoretical plates.
  • internals fillers structured packings or trays can be used.
  • the column is operated at a pressure of 1 to 30 bar.
  • the pressure in the column is above the operating pressure of the hydrogen chloride oxidation reactor.
  • the pressure in the column is 0.5 to 15 bar above the operating pressure of the hydrogen chloride oxidation reactor.
  • the liquid hydrogen chloride stream can be easily prepared by condensation at 10 to 25 bar with a conventional refrigeration system at condensation temperatures of -10 to -40 ° C.
  • this is done in combination with e.g. an isocyanate or polycarbonate plant, since the low inert gas content of less than 10% allows for easy condensation.
  • Particularly advantageous is the composite with a distillative purification of hydrogen chloride, since hydrogen chloride is already obtained with higher purity in the vicinity of the dew point.
  • not all of the amount of HCl used in the HCl oxidation has to be liquefied.
  • hydrogen chloride is used in the process according to the invention, which is obtained in a process as effluent, in which hydrogen chloride is formed as a coupling product.
  • Such methods are for example
  • liquid hydrogen chloride makes the "cold" required for condensation in the low-temperature range (temperature ⁇ 20 ° C.) easy to use.
  • it ensures an increase in the HCl concentration upon direct introduction into the chlorine separation column, as a result of which the content of chlorine in the oxygen-containing recycle stream recycled to the hydrogen chloride oxidation reactor can be kept low.
  • the HCl dissolved in the chlorine during the condensation of the chlorine can be removed in a subsequent chlorine purification by distillation in a column as top product or liquid side draw in the amplifier section of the column.
  • the liquid stream IV is fed into a lower part of a second column K2 and another separately provided liquid hydrogen chloride stream V in an upper part of this second column, and a substantially chlorine-free, hydrogen chloride and oxygen-containing gas stream VI and a liquid stream VII consisting essentially of chlorine.
  • the gas stream VI is generally obtained as a top draw stream and the liquid stream VII generally as a bottom draw stream.
  • the column K2 is operated at a pressure of 1 to 30 bar, preferably at 3 to 15 bar.
  • the temperature at the bottom of the column is -50 to +90 ° C, preferably -40 to +60 ° C, the temperature at the top of the column is -80 to +10 ° C, preferably -60 to -10 ° C.
  • the stream III of the column K1 and, if appropriate, the stream VI of the column K2 are used for precooling the gas stream I containing oxygen and chlorine in a heat exchanger.
  • the liquid stream IV is fed into a second column K2 and separated into a hydrogen chloride and optionally traces of further gases such as C0 2 , N 2 and O 2 containing gas stream VI and a substantially consisting of chlorine liquid stream VII ,
  • the top draw stream VI is fed to the lower part of the column K1, the column K2 being operated at a higher pressure than the column K1.
  • the gas stream VI is obtained as the top draw stream and the liquid stream VII as the bottom draw stream.
  • the column K1 is operated at a pressure of 1 to 30 bar, preferably at 3 to 15 bar.
  • the temperature at the bottom of the column is -50 to + 90 ° C, preferably -40 to +60 ° C, the temperature at the top of the column is -80 to +10 ° C, preferably -60 to -10 ° C.
  • the stream III of the column K1 can be used for the indirect cooling of the gas stream I containing oxygen and chlorine in a heat exchanger.
  • the gas stream I containing oxygen and chlorine is precooled indirectly with liquid hydrogen chloride in a heat exchanger.
  • the gas stream I containing oxygen and chlorine may contain carbon dioxide and optionally further inert gases such as nitrogen and noble gases.
  • the columns K1 and K2 are combined to form a single column K1.
  • This column K1 has a reinforcing part and an output part, wherein the gas stream I in the middle of the column K1 between the rectifying section and stripping section and the separately provided liquid hydrogen chloride stream II are fed to the top of the column, and the ascending gaseous stream I with the descending liquid Stream II is brought into contact in the enrichment section of the column.
  • a substantially chlorine-free gas stream III containing hydrogen chloride and oxygen are obtained as top draw stream and a liquid stream IV consisting essentially of chlorine is obtained as bottom draw stream.
  • the invention further relates to a process for the production of chlorine from hydrogen chloride, comprising the steps of: a) feeding a hydrogen chloride-containing stream a1 and an oxygen-containing stream a2 into an oxidation zone and catalytic oxidation of hydrogen chloride to chlorine, wherein a product gas stream a3 containing chlorine, Water, oxygen, carbon dioxide and inert gases is obtained; b) contacting the product gas stream a3 in a phase contact apparatus with aqueous hydrochloric acid I and at least partially separating water and from
  • a hydrogen chloride-containing stream a1 is fed with an oxygen-containing stream a2 into an oxidation zone and catalytically oxidized.
  • at least part of the hydrogen chloride passed into step a) originates from the separate hydrogen chloride stream e fed into the chlorine separation step e).
  • Suitable catalysts include, for example, ruthenium oxide, ruthenium chloride or other ruthenium compounds on silica, alumina, titania or zirconium dioxide as a carrier. Suitable catalysts can be obtained, for example, by applying ruthenium chloride to the support and then drying or drying and calcining. In addition to or instead of a ruthenium compound, suitable catalysts may also contain compounds of other noble metals, for example gold, palladium, platinum, osmium, iridium, silver, copper or rhenium. Suitable catalysts may further contain chromium (III) oxide.
  • the catalytic hydrogen chloride oxidation may be carried out adiabatically or preferably isothermally or approximately isothermally, batchwise, preferably continuously, as flow or fixed bed processes. Preferably, it is carried out in a fluidized bed reactor at a temperature of 320 to 450 ° C and a pressure of 2 to 10 bar.
  • catalyst body When driving in a fixed bed can also several, ie 2 to 10, preferably 2 to 6, more preferably 2 to 5, in particular 2 to 3 connected in series reactors with additional intermediate cooling can be used.
  • the oxygen can be added either completely together with the hydrogen chloride before the first reactor or distributed over the various reactors.
  • This series connection of individual reactors can also be combined in one apparatus.
  • As a form of catalyst body are any forms, preferably are tablets, rings, cylinders, stars, wagon wheels or balls, particularly preferred are rings, cylinders or star strands.
  • Ruthenium compounds or copper compounds on support materials are particularly suitable as heterogeneous catalysts, preference being given to optionally doped ruthenium catalysts.
  • Suitable support materials are, for example, silicon dioxide, graphite, rutile or anatase titanium dioxide, zirconium dioxide, aluminum oxide or mixtures thereof, preferably titanium dioxide, zirconium dioxide, aluminum oxide or mixtures thereof, particularly preferably gamma or alpha alumina or mixtures thereof.
  • the copper or ruthenium-supported catalysts can be prepared, for example, by impregnating the support material with aqueous solutions of CuCl 2 or RuCl 3 and optionally a promoter for doping, preferably in the form of their chlorides. to be obtained.
  • the shaping of the catalyst can take place after or preferably before the impregnation of the support material.
  • alkali metals such as lithium, sodium, potassium, rubidium and cesium, preferably lithium, sodium and potassium, more preferably potassium, alkaline earth metals such as magnesium, calcium, strontium and barium, preferably magnesium and calcium, more preferably magnesium, rare earth metals such Scandium, yttrium, lanthanum, cerium, praseodymium and neodymium, preferably scandium, yttrium, lanthanum and cerium, more preferably lanthanum and cerium, or mixtures thereof.
  • alkaline earth metals such as magnesium, calcium, strontium and barium, preferably magnesium and calcium, more preferably magnesium, rare earth metals such Scandium, yttrium, lanthanum, cerium, praseodymium and neodymium, preferably scandium, yttrium, lanthanum and cerium, more preferably lanthanum and cerium, or mixtures thereof.
  • Preferred promoters are calcium, silver and nickel. Particularly preferred is the combination of ruthenium with silver and calcium and ruthenium with nickel as a promoter.
  • the support material can be dried after impregnation and doping at temperatures of 100 to 500 ° C, preferably 100 to 400 ° C, for example, under a nitrogen, argon or air atmosphere and optionally calcined. Preference is first dried at 100 to 200 ° C and then calcined at 200 to 400 ° C.
  • the volume ratio of hydrogen chloride to oxygen at the reactor inlet is generally between 1: 1 and 20: 1, preferably between 2: 1 and 8: 1, more preferably between 2: 1 and 5: 1.
  • a step b) the product gas stream a3 is contacted in a phase contact apparatus with aqueous hydrochloric acid I and water and hydrogen chloride partly separated from the stream a3, leaving a gas stream b containing hydrogen chloride, chlorine, water, oxygen, carbon dioxide and optionally inert gases.
  • this step which can also be referred to as quenching and absorption step, the product gas stream a3 is cooled and at least partially water and hydrogen chloride are separated from the product gas stream a3 as aqueous hydrochloric acid.
  • the hot product gas stream a3 is cooled by contacting it with dilute hydrochloric acid I as quenching agent in a suitable phase contactor, for example a packed or tray column, a jet scrubber or a spray tower, absorbing a portion of the hydrogen chloride in the quench medium.
  • a suitable phase contactor for example a packed or tray column, a jet scrubber or a spray tower, absorbing a portion of the hydrogen chloride in the quench medium.
  • Quenching and absorbing agent is hydrochloric acid, which is not saturated with hydrogen chloride.
  • the phase contact apparatus is designed in two stages, the first stage being a whistle quench apparatus and the second stage is a falling film heat exchanger.
  • This embodiment of the phase contact apparatus as a pipe quench has the advantage that no expensive corrosion-resistant material such as tantalum must be used, since the product contacted parts of the quench apparatus come into contact only with cooled hydrochloric acid. It can therefore be used inexpensive materials such as graphite.
  • the phase contact apparatus is operated with circulating hydrochloric acid I.
  • aqueous hydrochloric acid for example, 1 to 20%, taken from the Phas contact point and subsequently distilled, gaseous hydrogen chloride and a hydrogen chloride depleted aqueous hydrochloric acid II are obtained, and wherein the hydrogen chloride in Step a) is returned and at least a portion of the aqueous hydrochloric acid II is returned to the Phasenmindapparat.
  • the hydrochloric acid distillation can be carried out in several stages.
  • a pressure distillation can be carried out, wherein at the top of the column hydrogen chloride and the bottom azeotrope boiling, dilute hydrochloric acid having a hydrogen chloride content in the range of, for example, 15 to 22 wt .-% is obtained.
  • the bottom draw stream of the pressure distillation column is subsequently subjected to a vacuum distillation, wherein at the top of the column of the vacuum distillation column water and at the bottom of a higher concentrated azeotropically boiling hydrochloric acid with a hydrogen chloride content of, for example, 20 to 28 wt .-% is obtained.
  • the hydrochloric acid obtained by pressure and vacuum distillation can each be partially or completely recycled to the phase contact apparatus and combined with the circulating liquid.
  • the gas stream b leaving the phase contact apparatus contains chlorine, hydrogen chloride, water, oxygen, carbon dioxide and in general also inert gases. This can be freed in a subsequent drying step c) by bringing into contact with suitable drying agents of traces of moisture. Suitable drying agents are, for example, concentrated sulfuric acid, molecular sieves or hygroscopic adsorbents. There is obtained a substantially anhydrous gas stream c containing chlorine, oxygen, carbon dioxide and optionally inert gases. Before the drying step c), the gas stream b is generally cooled.
  • the gas stream c is optionally compressed and optionally cooled, whereby a compressed or cooled or compressed and cooled gaseous stream c is obtained.
  • the gas stream c is cooled by cooling with a liquid hydrogen chloride stream in a heat exchanger.
  • the cooled stream generally has a pressure in the range of 2 to 25 bar and a temperature in the range of -50 to 0 ° C.
  • a step e) the stream c is fed into a lower part of a column K1 and a separately provided liquid hydrogen chloride stream e in an upper part of the same column K1 and the ascending gaseous stream c is brought into contact with the descending liquid stream e gaseous chlorine from the stream c condenses and liquid hydrogen chloride evaporated from the stream e, wherein a substantially chlorine-free gas stream e1 containing hydrogen chloride, oxygen, carbon dioxide and optionally inert gases and a liquid stream e2 containing chlorine are obtained.
  • the essentially chlorine-free gas stream e1 is obtained as top draw stream and the liquid, chlorine-containing stream e2 as bottom draw stream.
  • the liquid stream e2 is fed into a lower part of a second column K2 and another separately provided liquid hydrogen chloride stream e3 in an upper part of the same column, and a substantially chlorine-free, hydrogen chloride and oxygen-containing gas stream e4 as a top draw stream and in the Essentially consisting of chlorine existing liquid stream e5 as bottom draw stream.
  • the essentially chlorine-free gas stream e4 is obtained as the top draw stream and the liquid stream e5 consisting essentially of chlorine as the bottom draw stream.
  • the top draw stream e1 of the column K1 and, if appropriate, the top draw stream e4 of the column K2 are used for precooling the gas stream d containing oxygen and chlorine in a heat exchanger.
  • the liquid stream e2 is fed into a second column K2 and separated into a hydrogen chloride and oxygen-containing gaseous top draw stream e4 and an essentially chlorine-comprising liquid bottom draw stream e5, and the top draw stream e4 is fed to the lower part of the column K1 , wherein the column K2 is operated at a higher pressure than the column K1.
  • the stream e4 is obtained as the top draw stream and the stream e5 as the bottom draw stream.
  • the gas stream c containing oxygen and chlorine is precooled in a heat exchanger with liquid hydrogen chloride.
  • the hydrogen chloride-containing top take-off stream e1 and optionally the hydrogen chloride-containing top take-off stream e4 are at least partially fed into the oxidation step a) of the process.
  • a partial stream for the discharge of carbon dioxide and optionally further inert gases is preferably separated before feeding into the oxidation step.
  • the separated Purgegasstrom is subjected to the separation of hydrogen chloride of a wash with water or aqueous hydrochloric acid.
  • the purge gas stream is brought into contact with a solution containing sodium hydrogencarbonate and sodium hydrogen sulfite having a pH of 7 to 9 for the separation of very small amounts of chlorine.
  • the purge gas stream is preferably contacted in a wash column with a recycle stream containing sodium bicarbonate and sodium sulfite having a pH of about 7.0 to 9.0.
  • the pumped circulation is fed to the top of a wash column. Essentially, the following (equilibrium) reactions take place: (1) C0 2 + H 2 0 + NaOH - NaHC0 3 + H 2 0
  • a portion of the bottom draw stream containing NaCl, NaHS0 4 / Na 2 S0 4 , NaHS0 3 / Na 2 S0 3 and NaHC0 3 is discharged.
  • the Umpumpstrom is supplemented by alkaline aqueous sodium sulfite solution. Because of this procedure, only little carbon dioxide is bound results in a relatively low NaOH consumption of the washing step.
  • FIG. 1 shows a design according to the prior art. Special embodiments of the method according to the invention are shown in FIGS. 2 to 4.
  • FIG. 1 shows, by way of example, a conventional separation of chlorine from a crude gas stream containing oxygen, chlorine, hydrogen chloride and inert gases. Also shown by way of example is a heat integration measure.
  • the condensation takes place predominantly in the heat exchanger W2 operated with conventional cooling media.
  • the condensed crude chlorine 2 is fed to purify a distillation column K1 with W3 as an evaporator and W4 as a reflux condenser. In the bottom of the column specification-compliant liquid chlorine is recovered as stream 4.
  • the separated low boilers 5, essentially hydrogen chloride, oxygen, carbon dioxide and nitrogen leave the column in gaseous form via the top or via the condenser W4.
  • the heated gas stream 7 contains HCl, oxygen, carbon dioxide, chlorine and nitrogen and is predominantly recycled to the hydrogen chloride oxidation.
  • FIG. 2 shows by way of example the condensation of chlorine from a gas mixture containing chlorine, hydrogen chloride, oxygen, carbon dioxide and further inert gases according to the present invention. Also exemplified is a heat integration measure.
  • liquid hydrogen chloride 5 is given as reflux. Due to the intensive heat and mass transfer in the column of hydrogen chloride is evaporated and the chlorine condensed out of the gas stream.
  • the gaseous head take-off 10 of the column K1 contains only a small amount of ge amounts of chlorine.
  • the liquid bottom effluent 7 contains predominantly chlorine.
  • This condensed crude chlorine 7 is - fed together with an optionally liquid substream 2 of the crude gas stream - for further purification of a distillation column K2.
  • a distillation column K2 At the bottom of the column specification-compliant liquid chlorine 9 is obtained.
  • the column K2 has no top condenser, but as in column K1, liquid hydrogen chloride 6 is added as reflux to the top of the column.
  • the hydrogen chloride is also vaporized in the column K2 as a result of the intensive heat and mass transfer, and a larger chlorine concentration in the gaseous top takeoff is prevented.
  • the low boilers present in the feed to the column K2-essentially oxygen, hydrogen chloride, carbon dioxide and inert gases -leave the column in gaseous form overhead as stream 11.
  • the gaseous top draw streams 10 and 11 are combined to stream 12 and to precool the raw gas stream 1 via the heat exchanger W1 headed.
  • the heated gas stream 13 is predominantly fed into the hydrogen chloride oxidation.
  • FIG. 3 a shows by way of example a variant of the condensation of chlorine from a crude gas mixture comprising chlorine, hydrogen chloride, oxygen, carbon dioxide and further inert gases according to the present invention.
  • the cooled crude gas stream 3 which may also be two-phase, is fed into the bottom of a countercurrent column K1.
  • a countercurrent column K1 At the top of the column K1 is charged as reflux liquid hydrogen chloride 4. Due to the intensive heat and mass transfer in the column of hydrogen chloride is evaporated and the chlorine condensed out of the gas stream.
  • the liquid bottom effluent 5 contains predominantly chlorine.
  • the condensed crude chlorine is - supplied together with an optionally liquid substream 2 of the crude gas stream - as stream 6 for further purification of a distillation column K2.
  • At the bottom of the column specification-compliant liquid chlorine 8 At the bottom of the column specification-compliant liquid chlorine 8 is obtained.
  • the low boilers present in the feed to the column K2 - essentially oxygen, hydrogen chloride and carbon dioxide and further inert gases - leave the column in gaseous form as stream 7 overhead.
  • FIG. 3b shows a variant of the embodiment according to FIG. 3a, in which both columns K1 and K2 are operated at the same pressure and have been combined to form a column.
  • this single column comprises a reinforcing part and an output part, wherein the cooled crude gas stream 3 and a liquid part stream 2 of the crude gas stream are added in the middle of the column.
  • K1 is given as reflux liquid hydrogen chloride. Due to the intensive heat and mass transfer in the enrichment section of the column, which corresponds to the column K1 according to Figure 3a, hydrogen chloride is evaporated and the chlorine condensed out of the gas stream.
  • the stripping section of the column which corresponds to the column K2 according to FIG.
  • the liquid bottom draw contains essentially pure chlorine.
  • the gaseous top take-off 9 of the column K1 is predominantly chlorine-free. This is used for precooling the crude gas stream in the heat exchanger W1 and passed as stream 10 predominantly in the hydrogen chloride oxidation.
  • Figure 4 shows an example of a variant of the method according to the invention with additional indirect cooling of the crude gas mixture with liquid hydrogen chloride in a heat exchanger.
  • the dried, predominantly chlorine and oxygen and other gases such as HCl, CO2 and nitrogen containing crude gas stream 1, as obtained for example on the pressure side of a compressor, is further cooled in the heat exchanger W1.
  • the cooled crude gas stream which may also be two-phase, is passed into a second heat exchanger W2, where it is further cooled and largely condensed.
  • the amount of heat removed in W2 causes evaporation of liquid hydrogen chloride on the other side of the heat exchanger surface.
  • liquid hydrogen chloride 7 is given as reflux. Due to the intensive heat and mass transfer in the column, the hydrogen chloride is evaporated and further chlorine condensed out of the crude gas stream.
  • the gaseous top draw stream 1 1 of the column contains only small amounts of chlorine.
  • the liquid bottoms 9 contains predominantly chlorine and is combined with the optionally liquid partial stream 2 of Rohchlors from the W2.
  • the combined chlorine stream 10 is fed to a further purification of a distillation column K2. In the bottom of the column specification-compliant liquid chlorine is recovered as stream 12.
  • the column K2 has no top condenser, but it is liquid hydrogen chloride 8 is given as reflux to the top of the column.
  • the gaseous top takeoff streams 1 1 and 13 are combined and as stream 14 for Vorkuhr- the raw gas stream over the Retreated heat exchanger W1.
  • the heated gas stream 15 is driven predominantly into the hydrogen chloride oxidation reactor.
  • Table 1 shows the conditions and composition of the streams in the process of Figure 1 again.
  • Table 2 shows the conditions and composition of the streams in the process of Figure 2 again.
  • Table 3a shows the conditions and composition of the streams in the process according to FIG. 3a.
  • Table 3b shows the conditions and composition of the streams in the process according to FIG. 3b.
  • Table 4 shows the conditions and composition of the streams in the process according to FIG. Table 1
  • ARGON% weight% 2.1% 0.0% 5.0% 0.0% 0.5% 4.7% 4.7%
  • ARGON% weight% 2.1% 0.0% 2.3% 0.0% 0.0% 0.0% 0.0% 0.0%
  • ARGON% weight% 2.1% 0.0% 2.3% 0.0% 0.0%
  • ARGON% weight% 2.1% 0.0% 2.3% 0.0% 0.0% 2.3% 2.3%
  • ARGON% weight% 2.1% 0.0% 4.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

L'invention concerne un procédé pour séparer le chlore présent dans un flux gazeux I contenant de l'oxygène et du chlore, caractérisé en ce que le flux gazeux I est introduit dans une partie inférieure d'une colonne K1 et un flux de chlorure d'hydrogène liquide II préparé séparément est introduit dans une partie supérieure de ladite colonne, et le flux gazeux I ascendant est mis en contact avec le flux liquide II descendant. Le chlore est condensé hors du flux I et le chlorure d'hydrogène est vaporisé hors du flux II. Un flux gazeux III sensiblement exempt de chlore et contenant le chlorure d'hydrogène et l'oxygène ainsi qu'un flux liquide IV contenant le chlore sont obtenus.
EP12705829.5A 2011-02-18 2012-02-16 Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore Withdrawn EP2675752A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP12705829.5A EP2675752A1 (fr) 2011-02-18 2012-02-16 Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP11155077 2011-02-18
EP12705829.5A EP2675752A1 (fr) 2011-02-18 2012-02-16 Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore
PCT/EP2012/052660 WO2012110587A1 (fr) 2011-02-18 2012-02-16 Procédé de distillation pour séparer le chlore présent dans des flux gazeux contenant de l'oxygène et du chlore

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EP2675752A1 true EP2675752A1 (fr) 2013-12-25

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EP (1) EP2675752A1 (fr)
JP (1) JP2014510009A (fr)
KR (1) KR20140010404A (fr)
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WO (1) WO2012110587A1 (fr)

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CN103693620A (zh) * 2013-12-18 2014-04-02 常熟振氟新材料有限公司 从氯气与氯化氢混合气体中分离回收氯气的装置
CN103832975B (zh) * 2014-01-24 2015-10-28 上海方纶新材料科技有限公司 从含氯和氧的混合气中回收氯气和氧气的方法
CN107715491A (zh) * 2017-11-21 2018-02-23 滨化集团股份有限公司 一种氯气精制生产装置
CN108525337B (zh) * 2018-05-29 2023-07-18 杭州东日节能技术有限公司 一种稀盐酸真空浓缩塔及其使用方法
US20240208814A1 (en) * 2021-04-21 2024-06-27 Basf Se Process for preparing chlorine

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GB1139523A (en) * 1966-02-10 1969-01-08 Pullman Inc Recovery of halogens from gaseous mixtures
DE19535716A1 (de) 1995-09-26 1997-03-27 Bayer Ag Verfahren zur Aufarbeitung der Reaktionsgase bei der Oxidation von HCI zu Chlor
AU2003232761A1 (en) * 2002-05-15 2003-12-02 Basf Aktiengesellschaft Methods for producing chlorine from hydrogen chloride
KR101379634B1 (ko) * 2006-01-27 2014-03-28 바스프 에스이 염소의 제조 방법
DE102006023581A1 (de) 2006-05-19 2007-11-22 Bayer Materialscience Ag Verfahren zur Abtrennung von Chlor aus dem Produktgas eines HCI-Oxidationsprozesses
DE102007013964A1 (de) * 2007-03-23 2008-09-25 Bayer Materialscience Ag Prozess zur Entfernung und Rückführung kondensierbarer Komponenten aus chlorhaltigen Gasströmen
DE102007018014A1 (de) * 2007-04-17 2008-10-23 Bayer Materialscience Ag Wärmeintegration in einem Deacon-Prozess

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WO2012110587A1 (fr) 2012-08-23
KR20140010404A (ko) 2014-01-24
CN103380078A (zh) 2013-10-30
JP2014510009A (ja) 2014-04-24
CN103380078B (zh) 2016-01-13

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