Presentation on theme: "Measures of solid hydrogen contamination problem in the liquid helium"— Presentation transcript:
1Measures of solid hydrogen contamination problem in the liquid helium 6th International Workshop on Cryogenics Operations on November 2014Measures of solid hydrogen contamination problem in the liquid heliumHiroshi Ikedaa,*, Yutaka. Kondoa Research Facility Center for Science and Technology Cryogenics Division,University of Tsukuba, Tsukuba, Ibaraki , Japan
2CONTENT Introduction History of L280 in University of Tsukuba The trouble with solid hydrogenPurity measurement and state understanding of internal purifier (New method !)Improving method the purity of the regeneration gasGas chromatograph mass spectrometer impurity analysis of helium liquefaction machineConsideration of decreased purity (Changes in Linde helium Liqufier）Conclusions
3Introduction・In recent years, several universities that renewed their helium liquefier system have reported that solid hydrogen was mixed within the liquid helium produced by a helium liquefier. ・The University of Tsukuba has also installed a Linde L280 helium liquefier system in October Similar to other universities, cases where the helium flow of cryogenic equipment with flow impedance was blocked began to be reported around March ・In this work we focused on the internal purifier of the helium liquefier for the problem where solid hydrogen is mixed in the liquid helium produced by a helium liquefier.
11The trouble with solid hydrogen Flow impedance blocked by solid hydrogenQuantum Design MPMSPPMS(equipment to control temperature while limiting the flow of helium by a filter and capillary)
12Trouble Instrument Worldwide！ Japan Korea China India Spain France GermanyWorldwide！
13Purity measurement and state understanding of internal purifier New method！
14Gas bag purity is reduced to 95% by the regeneration gas, introduction into the internal purifier, differential pressure occurs.‣ For gas purity measurement discharged from the internal purifier was installed simple helium purity monitor immediately after the flow meter.
15Simple purity monitor installation flow diagram Gas BagCV3415CV3401V3410CV3430CV3420FlowMeterCold Gas FlowImpurer Helium GasCV3435TI3475TI3465HeaterPI3401PI3445HP LineLP LineLiqid Air１００％Purity MonterCV3410Atmospheric release
16Simple helium gas purity monitor New Method！Ulvac WP-01Pirany type SKD-20
17A result of the purity measurement The purity of the regeneration gas was reduced to 33% at maximumInitial setting valu・Purification operation stateCold end temperature TI3475 = 32.5 KInternal pressure PI3445 = 2.5 MPa・ Regeneration during operation Exit flow meter flow rate = 120 L/min Regeneration completion temperature TI3465 = 140 K Heater control temperature TI3475 = 95 K Warming heater output R3470 = 18 ％
18Improving method the purity of the regeneration gas
19Comparison with the liquefier Internal purifier Cold end temperatureInternal purifier Exit flow rateTCF50L280２７．５ K２００ L/min３２．５ K１２０ L/minHigh temperature! Low flow rate!
20Setting changes 120L/min⇒190L/min CV3415 CV3401 V3410 CV3430 CV3420 Down fromD32.5KGas BagCV3415CV3401V3410CV3430CV3420FlowMeterCold Gas FlowImpurer Helium GasCV3435TI3475TI3465HeaterPI3401PI3445HP LineLP LineLiqid Air１００％Purity MonterCV3410Atmospheric release
21Internal purifier regeneration gas purity measurement results 32.5K120L/min
22Internal purifier regeneration gas purity measurement results 29.0K190L/min26.0K190L/min32.5K120L/min
23Trend graph of the regeneration gas purity after improvement 26.0K190L/minΔP＝0.039MPa
25Gas chromatograph mass spectrometer impurity analysis of helium liquefaction machine
26Gas chromatograph mass spectrometer SHIMADZU GC-2014O
27Gas chromatograph mass spectrometer impurity analysis of helium liquefaction machine
28Improvement result The purity of the regeneration gas, 33% ⇒ 99% Cold end temperature change, the regeneration gas flow rate increase The purity of the regeneration gas, 33% ⇒ 99%Pressure difference is reduced. Purification operation has stabilized
29Consideration of decreased purity (Changes in Linde helium Liqufier）
301996 TCF50 Flow diagrams Adosorber 3 point ! 80K 20K LHe GHe LN2 Gas BagInPur GHeAdosorber3 point !
312010 L280 Flow diagrams Adsober Only One 20K LN2 LHe GHe Gas Bag InPur GHeGas Bag
322014 L140 New Flow diagrams Adosober Revival ! 20K LN2 LHe GHe Gas Bag InPur GHe
33ConclusionsRegeneration gas purity was improved from 33% to 99% by the setting change of internal purifier. Purification operation has stabilized generation of the differential pressure is reduced.By monitoring established the purity helium simple monitor, it can insight into the operating state of the internal purifier at a low cost.As the cause of differential pressure and decreased purity of the regeneration gas occurred, in addition to the incorrect setting, it is considered as the cause did not have the adsorber inside purifier.