Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/04—Purification or separation of nitrogen
  • C01B21/0405—Purification or separation processes
  • C01B21/0433—Physical processing only
  • C01B21/0438—Physical processing only by making use of membranes
  • C01B21/0444—Physical processing only by making use of membranes characterised by the membrane
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
  • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
  • F25J3/0685—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases
  • F25J3/069—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases of helium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/08—Separating gaseous impurities from gases or gaseous mixtures or from liquefied gases or liquefied gaseous mixtures
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0029—Obtaining noble gases
  • C01B2210/0031—Helium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/40—Processes or apparatus using other separation and/or other processing means using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/80—Processes or apparatus using other separation and/or other processing means using membrane, i.e. including a permeation step
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2215/00—Processes characterised by the type or other details of the product stream
  • F25J2215/30—Helium

Definitions

• the present invention relates to a process for the purification and recycling of helium and its application to the field of the manufacture of optical fibers.
• Helium which is a rare and expensive gas, is used, pure or in mixture with other gaseous compounds, in many processes, in particular in welding, in the medical field and respiratory gases, as cooling gas or gas marker ...
• optical fibers require several successive operations or steps, namely a deposition step, a consolidation step, a drawing step followed by a coating step, all of which consume variable quantities. helium; the fiber drawing step being the one that consumes the most.
• the deposition step on the fiber can be done using at least four different technologies, namely MCVD, OVD, VAD, PCVD. In most of these techniques, this step is preferably carried out in the presence of high purity helium, generally! purity greater than 99%, often at least 99.5%.
• the consolidation step can also be carried out according to the four aforementioned technologies and, here again, in the presence of helium of high purity, that is to say of a purity comparable to that of the deposition step.
• the optical fiber must be cooled under a gaseous helium atmosphere during a cooling step.
• This cooling step is conventionally carried out in a heat exchanger, often of an elongated cylindrical shape, which the exchanger is crossed by at least one fiber to be cooled which is cooled by contacting with a cold gas, preferably helium.
• a cold gas preferably helium.
• the helium used during this cooling does not need to be as pure as that used in the preceding steps, that is to say that helium with a purity of 80 to 99% is sufficient .
• the fiber is subjected to various treatments, in particular chemical or physicochemical, which take place during the abovementioned stages, which treatment generates a more or less significant pollution of the helium according to the stage considered.
• the cooling gas that is to say the helium
• the helium used is generally polluted in particular by atmospheric impurities, such as in particular nitrogen, oxygen, water vapor and argon, which can enter the cooling system, which is never completely sealed.
• the fiber or pre-fiber undergoes various chemical or physicochemical treatments which generate impurities, such as nitrogen, oxygen or water vapor, or other compounds, such as HCI, H 2 , Si and Ge.
• impurities such as nitrogen, oxygen or water vapor, or other compounds, such as HCI, H 2 , Si and Ge.
• the helium used during the cooling step can be recycled, that is to say recovered and purified, that is to say free of the impurities which it contains, before to be reintroduced into the exchanger used to cool the optical fiber.
• document US-A-5,890,376 describes a process for recycling the helium used in the consolidation step. According to this process, the impure helium is recovered, purified and returned either to the consolidation stage from which it comes, or to another stage of the process, which requires helium of lower purity, for example the stage fiber cooling.
• any fluctuation in the quantity or the quality of the filler can substantially alter the recovery of the desired product, in its purity or in the yield, unless reacting by acting on the adsorption cycle, which is ill conceived on a device installed by a user, such as a fiber optic manufacturer, and, at best, operated remotely
• the object of the invention is to propose a helium purification method which is improved compared to existing methods and which has the following advantages compared to the prior art - significant flexibility with regard to charge fluctuations, in particular quality and quantity,
• the present invention is based on a combination, in a specific order, of two independently known technologies, namely a cryogenic purification step of helium followed by a finishing step or treatment on one or more membranes.
• the present invention therefore relates to a process for the purification of impure helium, in which the impure helium is subjected at least to the following successive stages: (a) cryogenic refrigeration of the impure helium, and (b) permeation of at least one part of the helium from step (a).
• the invention also relates to a process for the purification of impure helium, in which the impure helium is subjected at least to the following successive stages: (a) cryogenic refrigeration of the impure helium so as to eliminate by condensation with at least part of the main impurities it contains and recovery of helium of intermediate purity containing residual impurities, and (b) permeation of at least part of the helium of intermediate purity from step (a) of so as to remove at least part of said residual impurities and recovery of helium having a final purity greater than said intermediate purity.
• optical fiber to designate either a fiber in its final state or in one of these intermediate states, that is to say in the form of a prefiber, for example , not yet or only partially stretched, or partially or completely treated;
• impure helium to designate helium containing impurities in variable quantities, in particular helium having been brought into contact with an optical fiber in a heat exchanger and;
• impurities to designate any compound, generally gaseous, other than helium capable of polluting said helium, for example nitrogen, oxygen, C0 2) water vapor, argon , HCI, H 2 , Si and Ge and their mixtures ....
• a fluid at cryogenic temperature typically at a temperature below about -150 ° C., for example at the temperature of nitrogen in the liquid state
• said contacting can be done by immersion of a coil or other means of heat exchange conveying impure helium in a bath of liquid nitrogen or by cooling said helium via a heat exchanger system of the countercurrent exchange type, in particular with brazed aluminum plates and fins,
• the purification process of the invention may include one or more of the following characteristics:
• cryogenic refrigeration of the impure helium is carried out by means of liquid nitrogen or of a fluid at cryogenic temperature brought into indirect contact with said helium, preferably by means of at least one heat exchanger.
• Helium permeation is carried out by means of one or more membranes, preferably several membranes in cascade.
• It includes at least one helium compression step at a pressure higher than 10 bar, preferably from 20 to 50 bar. - it includes at least one prepurification step, prior to the step
• the CO 2 and / or H 2 0 impurities are removed by adsorption, preferably by means of zeolite particles, this silica gel, of alumina or of their combinations.
• step (a) - helium compression is carried out prior to step (a) and by means of at least one compressor, such as a screw compressor.
• - It includes at least one step of reintroducing part of the helium leaving the retentate side of at least one membrane towards the suction of the compressor or towards an intermediate stage of said compressor.
• - impure helium is helium polluted by ambient air.
• - impure helium is helium containing at least one impurity chosen from the group formed by CO 2 , water vapor (H 2 O), argon, nitrogen and oxygen, preferably several of said impurities.
• step (a) Helium from step (a) at a purity of 75 to 98% by volume, preferably 90 to 95%.
• step (b) Helium from step (b) at a purity of 97 to 99.99%, preferably 99 to 99.9%.
• the invention also relates to a helium purification installation comprising, connected in series: - means for cryogenic refrigeration of helium enabling cryogenic refrigeration of the helium to be purified,
• the helium purification installation of the invention may include one or more of the following characteristics:
• Helium compression means making it possible to compress the helium to be purified are arranged upstream of the cryogenic refrigeration means.
• the helium compression means comprise a compressor and / or the permeation means comprise one or more membranes or membrane modules.
• the retentate output of at least one membrane or membrane module is connected to the input of at least said compressor.
• the invention also relates to a process for manufacturing at least one optical fiber, in which helium purified by a helium purification process according to the invention is used.
• the invention also relates to a method of manufacture of at least one optical fiber comprising at least the steps of:
• the invention also relates to a process for manufacturing at least one optical fiber comprising at least the steps of:
• step (i) recovering impure helium having been brought into contact with said fiber in said enclosure in step (i), (iii) purifying the impure helium originating from (ii) by a helium purification process according to one the invention.
• the method of manufacturing optical fiber of the invention may include one or more of the following characteristics:
• step (iii) includes a step of recycling at least part of the helium purified in step (iii) by re-contacting said purified helium with at least a portion of optical fiber.
• the helium and the optical fiber are brought into contact in at least one cooling enclosure.
• the gas used to cool the optical fiber is helium having a purity of 95 to 99.9999% by volume.
• It includes at least one deposition step, at least one consolidation step and at least one step of drawing the fiber, preferably helium, is used in several of these steps.
• FIG. 1 diagrammatically shows cryogenic refrigeration of impure helium by immersion in a bath of liquid nitrogen
• FIG. 2 shows diagrammatically a cryogenic refrigeration of the impure helium by contacting against the current with cryogenic nitrogen
• FIGS. 3 and 4 diagrammatically show the step of permeation of the residual impurities contained in the helium
• FIG. 5 shows diagrammatically the succession of steps of the method of the invention with reference to the supply of the compressor
• FIG. 6 is a graphic representation of the data recorded in the tables below.
• FIG. 7 shows schematically the application of the method of the invention to the manufacture of optical fibers with prepurification of impure helium.
• helium is polluted with atmospheric air, that is to say essentially impurities of the C0 2 , H 2 O and N 2 , O 2l type and the same references are used to designate the same parts in FIGS. 1 to 5 and 7.
• a prepurification 8 of the helium consisting of a conventional drying and decarbonation step, after compression of the helium at a pressure higher than 10 bars , generally of the order of 20 to 50 bars, intended to remove traces of moisture (H 2 O) and CO 2 present in helium.
• the helium in such a helium / dry air mixture can be purified in two successive stages and taken in this order, namely a cryogenic separation step 1 followed by a membrane permeation step 2, as shown on Figures 1 to 5 and 7.
• the evaluation of the shutdown efficiency is assessed simply from the vapor pressures of the gases at the cold point temperature (which will be taken at 79 K for a liquid nitrogen at 77 K), that is:
• the gas after condensation under a total pressure of, for example, 31 bar absolute (calculation hypothesis), then contains: 1, 22 bar of nitrogen; 0.26 bar of oxygen and 31 - (1, 22 + 0.26) bar of helium.
• a simple condensation step 1 with lost liquid nitrogen as shown diagrammatically in FIG. 1, that is to say by immersion of a coil 6 or the like conveying impure helium 10 in a bath 7 of liquid nitrogen where no refrigeration recovery is provided and the liquid nitrogen supports the entire load of cooling the gases and condensing the air; the condensates 4 being able to be evacuated via a purge line 40, - or a thermodynamically optimized solution, as shown diagrammatically in FIG. 2, using the gas / gas exchanges against the current and the expansions at the cold end that Joule-Thomson teach us, in which liquid nitrogen is only a supplement the cold behavior of the system which could even prove to be auto-thermal for certain pressure conditions.
• the gas 20 resulting from this cryogenic treatment undergoes purification by permeation 2 on one or more membranes, since it is dry, decarbonated and available under pressure equal to or greater than that generally required for treatment 2 permeation.
• each of these passages of helium on the membrane is accompanied by the rejection of a non-permeable part which will be recycled towards the inlet of the compressor.
• helium having these two levels of purity can be reused either on different production lines, or alternatively on the same production line, in particular in the case of fiber optic application, as shown in FIG. 7 .
• a manufacturing installation 25 has been schematized an optical fiber 27 comprising an enclosure 26 serving as a heat exchanger in which an optical fiber 27 is cooled by gaseous helium introduced into the enclosure 26 through an inlet orifice 28, in particular polluted impure helium in atmospheric air inlets, therefore essentially impurities of type N 2 , O 2 , C0 2 and H 2 O, being extracted from the enclosure 26 by an outlet orifice 29.
• the purified helium recovered from the permeate side 22 of the membrane 2 can be stored or returned directly to the inlet orifice 28 of the installation 25 for manufacturing optical fibers. Conversely, the helium recovered on the retentate side 23 of the membrane 2 is returned to line 10, upstream of the compressor 3, or then put into the atmosphere.
• the membrane 2 of the can be replaced.
• the permeate outlet 22 of the first membrane supplies the inlet of the second membrane
• the purified helium being recovered at the permeate outlet 22 of the second membrane before being returned to the inlet 28 of the enclosure 26 of the installation of FIG. 7,
• the gas recovered at the outlets 23 retentate first and second membranes can either be returned, for example in a single combined flow, to the inlet of compressor 3, as explained above, or be discharged to the atmosphere, or even used in another application or another step of process requiring lower purity helium.
• an additional helium can be connected to the inlet orifice 28 of the enclosure 26.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Manufacture, Treatment Of Glass Fibers (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-10-18 FR FR0013342A patent/FR2815399B1/fr not_active Expired - Fee Related
• 2001
  • 2001-10-10 WO PCT/FR2001/003126 patent/WO2002033334A2/fr not_active Ceased
  • 2001-10-10 JP JP2002536479A patent/JP2004518522A/ja not_active Withdrawn
  • 2001-10-10 CN CNA018175775A patent/CN1469986A/zh active Pending
  • 2001-10-10 BR BR0114770-6A patent/BR0114770A/pt not_active Application Discontinuation
  • 2001-10-10 EP EP01980593A patent/EP1336071A2/de not_active Withdrawn
  • 2001-10-10 US US10/399,718 patent/US20040050094A1/en not_active Abandoned
  • 2001-10-10 AU AU2002212406A patent/AU2002212406A1/en not_active Abandoned

Non-Patent Citations (1)

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