Hi everyone,
A few days ago I asked the list what knowledge they had on helium recovery
from their NMRs and did some research myself. I've summarized 3 options
which (Wall of text follows)
Option 1:
Conventional cryostat (LHe with LN) combined with a separate direct
recovery/liquefaction by Quantum Designs (ATL80/160)
(
http://www.qdusa.com/products/helium-liquefiers.html)
- Cost of ATL80: $110k, cost of ATL160: $130k
- ATL80: 80L capacity, integral air cooled compressor on cart (not magnet
safe)
- ATL160: 160L capacity, faster liquefaction, separate compressor from
dewar/coldhead (Sumitomo's I believe, various options for cooling) (magnet
safe)
- Liquefaction capacities far exceed normal helium boiloff (liquefaction
capacities of 12 and 22L/day of LHe produced given sufficient gas)
- Purification system not required for direct recovery, however it will
not capture helium losses during LHe transfers. The He line simply needs
to be flushed out with clean gas before reconnecting.
- Can use UHP helium gas from cylinders to produce LHe from clean
feedstock, allowing for independence from a helium shortage
- Can accept industrial helium gas (99.9% vs 99.9995%) via a cryogen free
purifier as a feedstock as well.
- Compressors can apparently throttle down to reduce power usage and
increase service cycles.
- Expandable for ~$40k to medium pressure recovery (crude He gas
compressor to tank, purification, and liquefaction) to allow for 100%
recovery of boiloff in a more compact footprint compared to large gas bags
Option 2:
Bruker Aeon Magnet
- 400/500MHz cost $100k extra (above current magnet costs) and provide 180
day LHe hold times
- 700/800MHz cost ~$200k extra (above current magnet costs) and provide 8
year LHe hold times
- The 400/500MHz Aeon magnets only have a single cryocooler to replace the
LN shield and does not actively cool the helium can. Since the heat shield
is cooler than LN temperatures it does reduce the LHe boil off.
- The 700/800MHz Aeon magnets have two cryocoolers to cool the heat shield
and the helium can (actively reliquefying in-situ) allowing for a 8 year
hold time.
- Both magnets require annual maintenance of the cryocooler(s) for
approximately $12k.
- In the event of a cryocooler failure and shutdown you have approximately
1 week until helium is lost and the magnet quenches (and this I am not
comfortable with)
- The cryocoolers are self contained and air-cooled in a large pedestal
adjacent to the magnet, supposedly Bruker has minimized all interferences
that it might generate by sitting near the magnet and isolated vibrations
from the helium can, but even this I'm a little skeptical of.
Option 3:
High pressure recovery system
- $300-500k as seen in many academic institutions with large helium usage
across multiple cryostats, many physics experiments, etc.
- The most 'conventional' helium recovery system that people seem to be
familiar with already.
Now, given our current price of helium at $11/L, and usage of ~120L/year
with a single magnet I won't be able to justify the costs. In the event of
either a shortage or significant price hike, the ATL160 would be more
reasonably justified. The option to add-on helium recovery at a later date
is more attractive than the Aeon magnets which seem to be a potential
disaster waiting to happen.
Rough estimates (not accounting for compressor/cold head service, or
operating utility costs)
3 year payback if LHe rises to $360/L
5 year payback if LHe rises to $216/L
Thanks & Regards,
Norman Chu
Received on Thu Jun 06 2013 - 05:24:27 MST