Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 1 ATLAS FCal Upgrade for sLHC: Modifications to the
Calorimeter Cryogenic System a Preliminary Study (cf. Eng.Note:
ATL-AE-EN-0017) ATLAS FCal Upgrade for sLHC: Modifications to the
Calorimeter Cryogenic System a Preliminary Study (cf. Eng.Note:
ATL-AE-EN-0017)
Slide 2
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 2 Cool-down time of one end-cap from room
temperature down to 90 K is about 9 weeks Cryo system designed to
cool-down one cryostat at a time Optimize scheduling modify cryo
system to be able to cool- down both end-caps in parallel How to
cool-down both end-caps in parallel? (1)
Slide 3
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 3 2.1 bar End-cap LAr Tanks LN 2 tank LN 2 pump
Expansion vessel 1.25 bar 5.3 bar Barrel End-Caps LN 2 phase
separator Cooling principles, a reminder How to cool-down both
end-caps in parallel? (2) Procedures : 1.Rinsing cycles 2.Gas
cooling: forced convection of GN 2 in heat exchangers inlet T
decreased on a ramp 3.Liquid cooling: circulation of vaporizing LN
2 4.Filling: Condensing of argon Cool-down rate limited by an
interlock triggered by the cooling criteria Cooling criteria:T must
be kept within strict limits to avoid excessive stresses or
displacements (< 645 K)
Slide 4
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 4 How to cool-down both end-caps in parallel? (3)
Limitations of the existing cryogenic system and proposed
modifications Nitrogen flow necessary in gas & liquid cooling
phases exceeds design flow of: The water heater used to warm-up the
gas to be vented above ground The water evaporator used to vaporize
liquid for the gas cooling phase The electrical heater used to
control the nitrogen gas temperature The distribution valve and
some foam insulated piping has to be replaced to accommodate these
changes. The stand-alone computer station and associated PVSS
software used to trigger the interlock is obsolete and need to be
re-built and integrated in DCS To be replaced
Slide 5
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 5 How to warm-up both end-caps in parallel? As for
the cool-down sequence, the warm-up time of one end-cap to room
temperature being about 8 weeks, in order to optimize the
scheduling of the FCal sLHC upgrade tasks it may be required to
warm-up both end-caps in parallel. The same PVSS software as for
the cool-down sequence is used leading to the same requirement to
rebuilt this system. No other cryogenics hardware modification is
in principle required.
Slide 6
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 6 How to bring extra cooling power to the FCal? (1)
At sLHC 400 W to 800 W additional beam induced heat load expected
in the FCal detector argon bubbling ? Absence of detailed
information about cooling requirements for the new FCal only
preliminary feasibility description of the modifications which
would be required to the existing cryogenic system How to bring an
extra cooling loop to the Fcal? 1. Option 1: 2 FCal extra cooling
loops coupled to the existing heat exchangers insert one FCal
cooling loop in series to each of the existing heat exchangers,
sticking to the same pipe diameter (20/22 mm) so as to preserve the
symmetry of these heat exchangers, to be able to control the flow
through them and to limit the pressure drop. going to a smaller
pipe diameter in the FCal volume would require careful study to
ensure that enough flow can be passed through the heat
exchangers.
Slide 7
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 7 Pipes routed from bayonets to FCal small cover
through vacuum space on cryostat cold cover surface How to bring
extra cooling power to the FCal? (2) Clearance between cold and
warm cover is 42 mm, superinsulation thickness is approximatively
12 mm which leaves about 30 mm to route the pipes along the cold
cover and final 8 mm clearance between superinsulation and warm
cover. Possible place to insert new cooling loop in series with
existing piping LN2 bayonet transition through vacuum space heat
exchanger return
Slide 8
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 8 How to bring extra cooling power to the FCal? (3)
Clearance is too small to route the piping. Can the design of the
new FCal cold cover be adjusted to allow routing of the pipes? 4 SS
pipes have to go through the FCal aluminum cold cover via
bi-metallic transitions to be included in new FCal cold cover
design detailed study required Bi-metallic transition used for the
existing LN2 heat exchangers through the cryostat cold shell FCal
cold cover
Slide 9
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 9 How to bring extra cooling power to the FCal? (4)
Theoretical clearance of 22mm, 12 mm superinsulation routing not
possible unless a local groove can be machined in the warm cover
Large omega weld details
Slide 10
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 10 How to bring extra cooling power to the FCal?
(5) 2. Option 2: 1 FCal dedicated cooling loop Adding a dedicated
cooling loop to the FCal, which could be controlled independently
from the existing heat exchangers would require much heavier
interventions: Manufacturing and installation of a new
heat-echangers regulation valve box (1/4VBN8) Manufacturing and
installation in the ATLAS chains of 2 new flexible transfer- lines
Modification of feed-though 8 (non equipped) or of warm shell in
the vicinity of the existing LN2 bayonet connections to accommodate
2 new bayonnet transitions through warm shell Installation of 2
pipes along the cold cover in the vacuum space to be welded to
bimetallic transitions prepared in the new FCal cold cover
Slide 11
Fcal upgrade for sLHC: Cryogenics modifications 01-03-2010 -
TE-CRG/ C.Fabre 11 Modifications to the cryogenic systemPreliminary
cost estimate 1. Parallel cool-down option Cool-down/warm-up
interlock software: 1 project associate for 6 months 30000 CHF
Modification of cryogenic hardware installation55000 CHF
Manufacturing of new vent water heater15500 CHF Manufacturing of
new evaporator water heater15500 CHF Manufacturing of a second GN2
electrical heater12000 CHF Installation + upgrade of existing
piping and valve12000 CHF 2. Parallel warm-up option (included in
the parallel cool-down option) Cool-down/warm-up interlock
software: 1 project associate for 6 months 30000 CHF 3. Option 1
for FCal extra cooling loop (for both end-caps)60000 CHF For 1
end-cap: manufacturing, installation and welding of 4 compensated
pipes including bimetallic transitions (manufacturing,
qualification and welding to FCal cover), 100% radiographic
control, tests and qualifications 30000 CHF 4. Option 2 for FCal
dedicated cooling loop (for both end- caps) In progress... Summary
of the modifications to the cryogenic system and associated
preliminary cost estimate Nota: Cost estimate based on a very
preliminary study, does not include any costing for access nor for
eventual radioprotection equipment.
