TM-1180
1670.000
March
1983
CRYOGENIC
SYSTEM
FOR
PRODUCTION
TESTING
AND
MEASUREMENT
OF
FERMILAB
ENERGY
SAVER
SUPERCONDUCTING
MAGNETS
W.E.
Cooper,
A.J.
Bianchi,
R.K.
Barger,
F.B.
Johnson,
K.J.
McGuire,
K.D.
Pinyan,
F.R.
Wilson
Fermi
National
Accelerator
Laboratoryr;
Batavia,
Illinois
60510
Summary
The
cryogenic
system
of
the
Fermilab
Magnet
Test
Facility
has
been
used
to
provide
cooling
for
the
test-
ting
of
approximately
1200
Energy
Saver
supercnnducting
magnets.
The
system
provides
liquid
helium,
liquid
nitrogen,
gas
purification,
and
vacuum
support
for
six
magnet
test
stands.
It
provides
for
simultaneous
high
'Current
testing
of
two
superconducting
magnets
and
non~
high
current
cold
testing
of
two
additional
magnets.
The
cryogenic
system
has
been
in
operation
for
about
32000
hours.
The 1200
magnets
have
taken
slightly
more
than
three
years
to
test.
System
Layout
The
major
components
of
the
cryogenic
system
are
shown
in
Figure
1.
Liquid
helium
for
cool~ng
the
mag-
nets
is
supplied
by
a
CTi/Sulzer
1500
Watt
refrigera-
tor.
Liquid
nitrogen
is
obtained
directly
from
trail-
ers.
The
helium
compressors
which
supply
the
refri-
gerator
also
provide
high
pressure
helium
gas
for
purg-
ing
magnets
before
cooldown
and
for
warming them
after
measurement.
Nitrogen
warm-up
gas
is
obtained
from
the
LN2
trailer
boil-off.
For
convenience
in
mounting
mea-
'surement
instrumentation,
the
test
stands
are
staggered
on
either
side
of
an
overhead
cryogen/gas
distribution
system.
Figure
1
Major
components
of
Cryogenic
System
I.
I-
I.
I-
c:::cJ-
L.ESEt-JD:
A.
HEl...IUM
GAS
'STORAGE
e.
Hl!.1...IUM
TUB!!.
TRAll...ER"S
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-!
-1
C:.
1...IQUID
IJITROCOEl-J
Ti:1All..litR"S
I.
I...
I...
0.
HEl...IUN\
C:0111PR6SSOR
BUll
..
01"-IG
AlJO
WATER
PUMP'S
E.
C.001...llJG
TOWER5
F.
AIR
COMPRE~'SOR
BUll...OllJ<O
Al.JO
WATER
PUM"'"S
G.
HEl...IUNI
PURIFIER'!>
H.
14El...IUWI
QUElo.ICl-1
TAlJIC."S
J:.
l-IEl...IU"1
REFRIGERATOR
COl...C
eox
.J.
l...IQUIC
HEl...IUM
OEWAl=I
K.
'!>UB·C.001..ER'S
At.IC
OIS"TRIBUTIOt.J
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1....
TEST
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Al
..
*
Operated
by
University
Research
Association,
Inc.
under
contract
with
the
U.S.
Department
of
Energy
(1)
Helium
System
Liquid
helium
is
provided
to
the
magnets
with
a
closed
cycle
refrigerator
system.
The
refrigerator
is
a
joint
CTi/Sulzer
design;
it
employs
two
Sulzer
TGL-22
gas
bearing
turbines
wf.th
magnetic
thrust
pre-
load.
Table
1
gives
typical
operating
parameters
for
the
turbines.
Helium
is
liqufied
through
a
J-T
valve
after
the
second
turbine
to
avoid
possibly
destructive
cavitation
in
the
turbine.
The
liquid
helium
inven-
tory
is
stored
in
a
10000
liter
dewar.
In
order
to
provide
forced
flow
through
the
magnets,
the
dewar
pressure
is
maintained
at
1.8
to
1.9
atm.
and
the
re-
turn
flow
from
the
magnets
is
routed
through
the
re-
frigerator
to
a
point
controlled
at
1.05
atm.
Table
1.
Typical
Turbine
Operating
Parameters
Turb±ne
Tl
T2
Inlet
press11re
(Atm)
8
to
14
10
to
14.5
Expansion
ratio
3.1
to
5.4
3.3
to
4.7
Flow
(g/s}
75
to
C)O
75
to
90
Inlet
temperature
(K}
16
to
22
7
to
9
Speed
(rps}
2900
to
3400 1800
to
2700
Helium
flow
for
the
refrigerator
is
provided
by
two
Sullair
C25L
oil
injected
screw
compressors.
A
multi-stage
oil
removal
system
recovers
oil
from
the
helfum
before
the
helium
passes
to
the
refrigerator.
Helium
gas
is
stored
in
a 4000
cubic
foot
buffer
tank
at
pressures
ranging
from
4
to
12
atmospheres.
Make-
up
helium
is
supplied
from
tube
trailers.
The
maxi-
mum
high
pressure
flow
of
the
compressor
system
is
about
210
g/s;
the
maximum low
pressure
flow
is
about
100
g/s,
This
maximum low
pressure
flow
limits
total
flow
to
the
test
stands
to
below
100
g/s.
Compressor
discharge
pressure
is
regulated
between
10
and
15
at-
mospheres
as
one
means
of
controlling
total
ref
riger-
a
tion.
Figure
2
gives
diagrams
of
the
compressor
and
refrigerator
systems.
Figure
2a
Helium
Compressor
IOOOHl:O
MOTOR
011...
REMOVAL
CHARCOAi..
AOSOR9ER
HEL.IUWt
!'"ROM
c.01..oeo'><
(2.(o
AT"1.)
'SUl...1..AIR
CZSL
C.ON1PRESSO<'l'S
l.OSA•M
2001-ll"
l'l\OTOR
I.OW
Pllll!l'SUR!!
HELIUNl
FR.OM
COLD
eox
I
l"U<'llFIER'S
10-l(o
A•M
GoAT~-~
WAlll<IUP
~
PURGIE
HEl..IUl<I
TO•ES•
5T,..lJO'S
"""lGH
PRe'S'SuRE
1-<El..IUM
•OCOl..0
Bol(
Figure
2b
Helium
Refrigerator
COLD
BOX
Tl
TC:
1-f)(
I,
H)(.2.
HX:I
1-11<4•
IA
'!5
10000
UTEl'I'
"-~~~~~~~~~~~-+-'
OE'NAR
Helium
gas
is
purified
with
two
activated
char-
coal
adsorbers
operated
at
LN2
temperature.
These
purifiers
have
manifolding
so
that
they
can
be
used
to
clean
system
gas,
tube
trailer
gas,
buffer
tank
gas,
quench
tank
gas,
or
return
gas
from
magnets
being
purged.
They
can
also
be
used
to
provide
high
purity
helium
for
decontamination
of
various
portions
of
the
system.
The
use
of
two
purifiers
allows
one
to
be
nsed
while
the
other
is
being
decontaminated.
Two
1000
gallon
tanks
are
used
for
temporary
stor-
age
of
helium
gas
recovered
from
quenching
magnets
and
serve
the
important
function
of
minimizing
system
dis-
ruption
from
the
quenching
of
magnets.
The
pressure
rise
in
these
tanks
during
a
severe
quench
is
less
than
2
atm.
The
tanks
limit
the
rise
in
the
low
pres-
sure
compressor
line
to
about
3
psi
during
severe
quenches.
Nitrogen
System
Nitrogen
is
supplied
to
the
system
from two
li-
quid
nitrogen
trailers.
Typically,
one
trailer
is
used
to
supply
liquid
and
the
second
to
supply
gas
from
boil
off
although
interconnections
permit
either
trailer
to
supply
both
liquid
and
gas.
Liquid
nitro-
gen
is
supplied
to
the
test
stands,
to
the
first
re-
frigerator
heat
exchanger
for
pre-cooling
the,
helium,
to
the
dewar
shield,
and
to
the
purifiers.
Nitrogen
gas
is
supplied
to
the
test
stands
for
warming
magnets
and
to
the
puri
Fiers
to
aid
in
war.m-up
for
dt"contamot-
nation.
Nitrogen
and
helium
systems
are
totally
se-
parated.
Distribution
System
and
Test
Stands
Liquid
helium
and
nitrogen
are
supplied
to
the
test
stands
through
a vacuum
insulated
distribution
box.
Connections
on
the
distribution
box
permit
warm
helium
and
nitrogen
gas
to
be
supplied
as
well.
A
diagram
of
the
box
is
given
in
Figure
3.
Helium
and
nitrogen
subcoolers
lower
the
incoming
liquid
tempera-
ture
and
help
ensure
that
the
liquid
is
bubble
free.
Valves
on
the
distribution
box
control
the
supply
of
liquid
helium,
liquid
nitrogert,
gaseous
helium,
and
gaseous
nitrogen
to
each
test
stand.
The
return
of
helium
liquid/gas
mixture
from
the
test
stands
can
also
be
controlled.
Connections
between
the
distribution
box
and
test
stands
are
made
through
vacuum
insulated
transfer
lines.
(?)
Figure
3
Distribution
Box
"
..
l:
I
"6
'6_
:
"'
I -
----+--+---
----
--~
I- ..
2 2
~
..J
2.1'
Me
I
MEl..IUM
NITROGl!!:IJ
'_'S_u_e_c_oo
__
:-e:R
'SUBC:o~1..1!R
I
WA"Wl·UP
-----
~A"!>
TM-1180
A
Diagram
of
the
stand
flow
system
is
given
in
Figure
4.
Figure
4
TEST
STANO
FL.OW
'S''('!ffEM
It
10
He
1"1
SU"'"''-"
E!:>JO
901(
.;
J
SUPPL.V
BQ'X
C~
E
J
1-
2
•
>
Each
stand
has
vacuum
insulated
supply
and
turn-
around
boxes
which
interface
the
magnet
under
test
with
cryogenic,
gas,
vacuum,
and
electrical
system.
Liquid
flow
is
from
the
downstream
to
the
upstream
end
o.f
the
magnet,
i.e.,
in
the
opposite
direction
from
the
proton
beam
in
the
ring.
Liquid
nitrogen
passes
through
the
magnet
in
only
one
d:l.rect:ton and :ts
vented
after
it
reaches
the
turn-around
box.
Liqu:td
helium
expands
through
a
J-T
valve
:tn
the
turn-around
box
and
returns
through
"2~"
magnet
passages
as
a
l:tquid/
gas
mixture.
Heat
exchange
in
the
magnet
between
this
mixture
and
the
liquid
in
the
"lf'
magnet
passages
lowers
the
1~
temperature.
l~
connections
between
the
magnet and endboxeA
use
Conoseal
f:tttings.
2~
and
LN2
connections
use
C-seal
fittings.
The magnet
insulating
vacuum commun-
icates
directly
w:tth
endbox
vacuum.
Unlike
the
instal-
lation
in
the
ring,
the
magnet beam
tube
vacuum com-
municates
with
the
magnet
insulating
vacuum on
the
test
stand.
A
double-walled
vacuum
insulated
tube
is
inAertecl
thro11p;h
the
en<lboxes
:Into
the
mnp;net
bore.
Th"li:i
tuhe
11lJnws room t·prnpl'rnt11rr• tn11trumrntnl: Ion
to
hi~
inserted
into
the
mngnet
bore
while
the
magnet
is
nt
cryn?,en
Ir
trmprrn
t11rrR.
~rn
IR
hrt·wr('n
t·h<'
011t<•r
wn
11
of
this
tube
and
the
endboxes
establish
vacuum
inte-
grity.
Stand/magnet
vacuum
is
provided
with
a
Sar-
gent-Welch
3106G (400
liter/second)
turbo-molecular
pump
backed
by
a
Sargent-Welch
1397
roughing
pump.
On
each
stand,
connections
are
made
to
each
end
box
using
6
inch
piping
from
the
pumping
station
located
centrally
below
the
magnet
position.
Magnet
coil
and
bus
superconducting
leads
are
brought
out
of
the
magnet
through
the
1+
passages.
At
the
turn-around
box,
the
magnet
coil
and
bus
leads
are
spliced
directly
together;
no
external
connection
is
made. At
the
supply
end
box
the
magnet
leads
are
spliced
to
superconductor
leads
which
are
part
of
the
end
box.
Modified
American
Magnetics
L-5000
gas
cooled
power
leads
are
used
to
connect
these
superconductors
to
external
power
buswork.
The
connections
between
the
American
Magnetic
leads
and
the
end
box
supercon-
ductors
are
made
using
copper
transition
pieces.
These
connections
are
made
in
an
internal
supply
box
can
through
which
the
supply
liquid
helium
flow
is
directed.
A
small
portion
of
the
flow
is
brought
out
of
the
top
to
the
internal
can
through
the
L-5000
leads
to
cool
them. At
the
turn-around
box,
the
coil-
bus
splice
is
made
in
the
1~
piping
at
the
interface
between
the
magnet
and
endbox.
A
J-T
valve
in
the
turn-around
box
allows
1~
liquid
to
expand
and
flow
as
a
liquid/gas
mixture
back
through
the
magnet
2f
pass-
ages.
Bypass
valving
is
connected
to
the
1~
piping
at
the
turn-around
box
and
to
the
2~
piping
at
the
turn
-around
and
supply
end
boxes.
This
bypass
valving
is
used
to
circumvent
effects
of
the
magnet
l~-2~
heat
exchange
during
magnet
cooldown. The same
lines
can
be
used
to
evacuate
the
magnet
helium
passages
for
decontamination
prior
to
cooldown.
The
relief
of
quench
gases
is
provided
through
4
paths.
At
the
supply
box,
1~
relief
is
provided
through
piloted
Fermilab
design
"Walker
valves"
and
parallel
pneumatically
operated
1~
inch
Whitey
valves.
Both
of
these
valves
are
opened
on
the
detection
of
a
quench.
The Walker
valve
will
also
open when
1~
pres-
sure
exceeds
30
psig.
Fermilab
design
"Kautzky
valves"
are
mounted on
the
magnet
l~
relief
port.
These
valves
are
set
to
open
at
a magnet
l~
pressure
of
32
psig.
Circle
Seal
lli;
inch
relief
valves
are
mounted
in
the
turn-around
box
l~
bypass
piping.
These
relieve
at
20
psig.
Each
relief
valve
is
connected
through
manifold-
ing
and
piping
to
the
quench
tanks
for
recovery
of
quench
gas.
Instrumentation
Except
for
on
the
test
stands,
hel:lum eyRtem
instrumentation
employs
Lakeshore
silicon
diodes
for
temperature
measurement,
Dynisco
transducers
for
pressure
measurement,
American
Magnetics
liquid
level
gauges,
venturi!!
:For
flow
measurement,
and
Televac
thermocouple
and col<l
cathode
gauges
for
vacuum
measurement.
Fisher
controllers
are
used
for
process
control.
Valve
control
and
additional
pres-
sure
monitoring
uses
equipment
from a
variety
of
man-
ufacturers
including
Fairchild,
Fisher,
Foxboro,
Moore, Rosemount, Dwyer,
Penn,
and
United
Electric.
A
Texas
Instrument
ST!
system
is
used
for
overall
process
control
and
system
interlocks,
Helium
pur-
ity
:l:s
monitored
with
a
"chromatograph"
syF1·tem
de-
veloped
by
R,
Walker.
2
Magnet
l~
and
2~
pressure
and
temperatures
are
measured
at
each
endbox
using
pressure
taps
and
conventional
presm1re
gauges
for
pressure
measurement
and
helium
vapor
pressure
thermometers
.for
tempera-
ture
measurement.
Venturi
gauges
in
the
It
transfer
line
to
each
stand
monitor
liquid
flow
to
the
stand.
Stand
temperatures,
pressures,
and
flows
are
manually
recorded
wtth
accurncies
nf
O.OlK,
0.25
psf,
nnd J.O
gram/second
respectiyely.
Interlocked
liquid
level
probes
in
the
endhox
internal
leA.d
can
emrnre
that
TM-1180
the
can
is
adequately
filled
during
testing.
Similar
instrumentation
is
used
to
monitor
the
helium
subcool-
er
on
the
distribution
box
and
the
overall
distribution
system
perfonnance.
Electrical
connections
are
made
through
the
supply
box
internal
can
and
the
1~
passage
to
the
magnet
to
the
endbox/magnet
splices.
Additional
connections
to
the
L-5000
leads
where
they
exit
the
endbox
are
used
to
protect
the
power
lead/magnet
combination.
Performance
The
helium
refrigerator
provides
alternatively
1900
Watts
of
refrigeration
or
250
liter/hour
of
liquification
under
normal
operating
conditions.
The
flexibility
of
the
compressor/refrigerator
controls
permits
this
capacity
to
be
reduced
by a
factor
of
approximately
10
so
that
changing
loads
are
easily
accollllllodated.
The
magnet
installation
time,
which
includes
magnet
positioning
and
levelling,
making
electrical
and
cryogenic
connections,
leak
checking,
and
perform-
ing
an
initial
decontamination
of
helium
passages,
takes
about
2
hours.
"Scrubbing"
to
further
clean
the
magnet
takes
an
additional
1
to
2
hours.
A
di-
pole
magnet
takes
about
4~
hours
to
cool
to
measure-
ment
temperature
and 5
to
6
hours
to
warm
for
removal
from
the
test
stand.
Quadrupole
magnets
take
2~
to
3
hours
to
cool
and
4
to
5
hours
to
warm.
Typical
para-
meters
for
a
cold
magnet
are
given
in
Table
2.
Table
2
Typical
Magnet
Cooling
Parameters
In
Out
1.j>
pressure
(psig)
8.5
to
10.0.
8.5
to
10.0
lp
temperature
(K)
4.62
to
4.74
4.63
to
4.75
2.p
pressure
(psig}
4.0
to
5.0
4.0
to
5.0
2.,,
temperature
(K)
4.49
to
4.55
4.49
to
4.55
Flow
(g/s)
23
to
29
23
to
29
Helium
lead
flow
per
power
lead
(g/s)
0.30
to
0.40
Nitrogen
shield
flow
(g/s)
3.5
to
4.2
The
careful
design
of
cryogenic
system
controls
has
permitted
the
system
to
be
staffed
by
only
5
re-
frigerator
operators.
The
system
is
routinely
run
24
hours/day
7
days/week.
It
has
been
operated
during
approximately
90%
of
calendar
time
during
the
past
3
years.
Maintenance,
repairs,
and
vacations
have
contributed
roughly
equally
to
the
10%
off
time.
This
high
duty
factor
of
the
cryogenic
system
has
been
an
important
factor
in
the
expeditious
measure-
ment
of
Energy
Saver
magnets.
Acknowledgements
3
Personnel
from
CTi ,
Sulzer
Brothers
Limited,
Sullair
Refrigeration,
CCI, nnd
CVI
were
particularly
helpful
f.n
contr1butln~
to
the
d1>s"f.gn
nf
the
system
and
bringing
it
into
operation.
We
wish
to
thank
the
rnumerous Fermi.lab
personnel
who
contributed
to
the
system,
especially
W.B.
Fowler,
R.
Walk~r,
M.E.
Stone,
.W.
Zimmerman, R. Yamada
and
D.A.
Gross.4
Reference
1.
W.E. Cooper
et
al.
A<lvances
in
Cryogen:l.c
Engineer-
ing,
Vol.
27,
(1982)
p.
617,
2.
R.
Walker,
Fermilab
Report
TM-742
(1977).
3.
Now
Koch
Process
Systems.
4.
Presently
at
General
Electric,
Inc.
Schenctady,
NY.
(3)
