IVAN Workshop Helium Recovery Systems in NMR Lab

IVAN Workshop Helium Recovery Systems in NMR Lab Cryomech LHe. P 22 with Atmospheric Recovery and Medium Pressure Gas Storage Kz Shein Master Scientific Research Technologist University Of Arkansas Chemistry/Biochemistry Department Fayetteville, AR 72701 Email: kshein@uark. edu, ph: 479 -575 -4589 (office), 479 -966 -6184 (cell)

Vendor Choice • Three vendor to choose from Quantum Design, Quantum Technologies and Cryomech. • Cryomech system cost between the other two vendors • Reasons of choosing Cryomech are: 1. Shorter delivery time after placing order 2. Recovery Bag requirement because of long magnet fill 3. Water cooled Recovery Compressor 4. More medium pressure gas storage(~75 L liquid equivalent) 5. lower Long-term maintenance cost Funding Source Initially, bring up estimated cost to spend on Liquid Helium, and Department Chair, Dr. Stites planned to borrow from higher administration. Install the system and pay back slowly. However, right place at the right time, internal funding available.

Cost of the System $ 203, 320 Installation Cost ~ $ 80 K Total Phase 1 and Phase 2 installation and parts Phase 1, ~$ 30 K (7 NMR Magnets ) • ~ $ 20 K, Parts include 200 ft of 2” Copper pipe, 1” copper pipe, S. S. Flex line, Heat exchangers, flow meters, pipe fittings • ~10 K, contractor to hang 2” pipe and Heat Exchanger assembly; using Sil-Fos Brazing Phase 2, ~$ 50 K (Adding 7 T MS and Recovery line extension into two building) • ~$ 10 K, Parts include 400 ft of 3” Copper pipe and fittings • ~$40 K, University Facility installation by Sil-Fos Brazing

Brief System Description • • • • Helium Gas Recovery (Bag, Compressor, 4 medium Pressure storage) Liquefier 22 Liters per day, with 150 Liters storage capacity Purifier with spare Liquid Nitrogen Cold Trap, spare absorbers for Purifier and Recovery Compressor, Heat Blankets 250 Liters Liquid Helium Storage with electronic level meter Liquid Helium Transfer Line Recover Magnet fills and normal Boil-off from 8 Magnets Daily Boil-off from 8 Magnets is ~6 Liters per day, Boil-off from Liquid storage is ~2 Liters per day. Liquefier running hour ~13 K hours, with ~65% Duty Cycle. Every 4 weeks Liquid Helium magnet fill with storage tank, ~ 160 Liters. Magnet fill is done by using 99. 999% Helium gas as push gas. Loss is ~6%, 99. 999% Helium gas to make up losses Make up Helium gas cost is estimated ~ $5 K per year. Medium pressure storage pressure maximum is 400 psi. Magnet fill must be managed not to reach maximum pressure. Maintain record of how much volume Liquid Helium fill in each magnet using electronic level meter equipped at storage tank. Magnet holding pressure set 0. 2 psi with Back Pressure Regulator, Recovery Bag and main line set at 0. 15 psi

Chemistry/Biochemistry NMR Lab Helium Recovery Layout Plan (Phase 1)

Chemistry/Biochemistry NMR Lab Helium Recovery Layout Plan (Phase 2)

NMR Lab Helium Recovery System Helium Purifier Helium Gas Recovery Bag Liquid Helium Plant

NMR Lab Helium Recovery connection to magnet Magnet fill Flow monitor Heat Exchanger Assembly for magnet fill

Maintenance Cost $2 K per year projected not including liquid Nitrogen cost of ~50 Liters per week • Liquefier Cold Head exchange 25 K-40 K hours, $6. 8 K (every 4 -5 years) • Liquefier Absorber replacement 25 K-40 K hours, $2. 3 K (every 4 -5 years) Regular Maintenance • Drain water form Recovery Compressor (daily if possible) • Liquid Helium transfer from Helium Liquefier tank to Storage tank (weekly) • Exchange Recovery Compressor Absorber and Regeneration (every 8 weeks or as needed per moisture indicator) • Purifier Liquid Nitrogen fill (~50 Liters weekly) • Purifier Cold Trap exchange and Regeneration (yearly or as needed per Helium Purity Sensor) • Leak test, water sensor(monthly)

Unexpected Events and Surprises • Intermittent Recover Compressor issue. When the bag full, compressor did not start. Issue was solved by Cryomech under warranty • Transfer line issue. liquid Helium was not transferred form Liquefier tank to Storage. Cryomech replaced transfer line under warranty • Purifier did not start automatically sometime. Problem solved by replacing lower control cabinet with nonconductive cover • Communication issue between Liquefier compressor and control computer, Restart application normally solve the issue 4 problems in 2. 5 years • Gas leak at Recovery Line and fitting after installation. Pressure hold 2 psi for Phase 1, and 1. 1 psi for phase 2 Recovery Line Leak Test Data Pressure Test (pressure hold at 1. 1 psi) Vacuum Test (115 microns)