Transcript Inert Gas Purification Systems

Inert Gas Purification
Systems
Why do we need them???
• Many of the materials used in research and
development today are extremely air
sensitive, and can be dangerous in the
presence of air.
• Purifiers are designed to remove oxygen,
moisture and nitrogen from an inert gas to
one part per million.
• Safety is also a critical issue in experiments
and research today.
Purifier Components
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Circulation blower
Copper catalyst
Molecular Sieve
Vacuum pump
Solenoid Assembly
Pressure control
Regeneration control
Manual footswitch
• Isolation valves
(automatic or manual)
• Solvent removal
systems
• Titanium reactor (in
the case of N2
removal)
• Exhaust traps
Purifier theory
The purpose of a purifier is to remove
oxygen and moisture from an inert
gas flowing through a controlled
atmosphere system such as a glovebox.
The typical purifier contains two
purification agents. One agent is a
molecular sieve which removes H2O
by process of molecular
adsorption.The other agent is called
Q5 and is an O2 absorbent material.
Oxygen removal
• Oxygen removal from Argon, Helium, or
Nitrogen is accomplished with a
reactant/catalyst known as Q5, a material
consisting of finely divided copper on an
Alumina Matrix. The copper reacts with
oxygen to form cupric oxide.
Moisture removal
• Moisture is removed by a molecular sieve
enclosed in the same container as the
Oxygen reactant. Also removed by the
molecular sieve at ambient temperatures are
carbon dioxide, nitrogen dioxide, hydrogen
sulfide, carbon monoxide and many organic
compounds including: Alcohol's, aromatics,
amines, halogenated compounds,
oxygenated compounds, hydrocarbons and
organic acids.
Regeneration Theory
• To restore the purification capability of the
material two reactions must take place.
• The H2O trapped by the sieve must be
removed completely.
• The O2 must be removed from the Cu and
returned to essentially pure form.
Regeneration theory (cont.)
• The restoration of the sieve is accomplished
by heating the material which vaporizes the
water. A dry gas is passed over the sieve
which carries the H2O off and out of the
column. The restoration of the the Q5 is
accomplished by passing a H2 rich gas
through the reactant. The H2 reacts with the
O2 and the reactant is reduced to pure Cu
with H20 as the by product which is then
pumped off.
Materials that can damage the
purifier
• Sulfur and Sulfur compounds such as H2S,
COS, SO2, SO3, These materials will
poison the reactant material in the purifier.
• Also, large quantities of Halides, Chlorides,
Halogens (Freon), Alchohols, Hydrazine,
Phosphene, Arsine, Arsinate, Mercury and
saturation with water may also deactivate
the Oxygen reactant. If any of these
materials are to be used, a suitable trap
should be installed.
Selecting a purifier
• Consider !
• The size of the Glove-box
• Determine the leak rates if applicable
• Calculate the frequency of ante chamber
operation
• Determine the desired purity level
Circulating Vs Purging
• When purging a glove-box the atmosphere
in the box can only achieve an O2 and H2O
level that is present in the source gas.
• Purging a box can be very expensive
depending on the gas and the volume of the
box to be purged.
• When using a closed loop circulation
purifier the supply gas does not need be
pure, it is the purifiers job to remove H2O
and O2 in the gas to the 1ppm level.
• The system only uses gas when transferring
in and out of the box.
Purifier options
• Purifiers can be configured with dual
columns for continuous operation.
• They can be configured for different flow
rates.
• In addition to standard configurations
custom solvent traps can be supplied for
removal of harmful materials that can
damage catalyst.
• Nitrogen removal systems are also
available.
Utilities required
• Two separate gases are required for standard
purifiers.
• One is your choice of inert gas. Argon,
Nitrogen or Helium with a delivery pressure
of approx. 35psi
• The other is your choice of inert gas with a
4-5% mixture of H2.(Regeneration gas)
• Electrical service. (varies depending on
configuration) typically 115vac/20 amps.
• Venting (application specific)
Instrumentation
• In order to determine the conditions of the
atmosphere in the glove-box the following
analyzers are available.
• Moisture
• Oxygen
• Nitrogen
• Other custom systems are available I.e.
GC/MS