Cryogenic system in P4: Possible options

Cryogenic system in P4:Possible options

S. Claudet & U. Wagner

LHC Workshop, “Chamonix XlV”January 2005

(Mostly for RF & beam scrubbing)

LHC Workshop CERN, January 2005

Session 3Cryo/RF Options

Content

Brief recall of present situation Concerns

– Cooling capacity– Pressure stability– Coupling with items operated at higher pressure– Periodic cavity conditioning and developments

Possible alternative cooling schemes Summary



Getting familiar with the subject

LHC Design report, p 134 for description of ACS cryogenics and requirements

Schematic views:– Single cavity module: LHCACSGA0006– QRL sector 3-4: LHCLSQR_0041– QRL sector 4-5: LHCLSQR_0042

Minutes of meetings between RF & Cryo Minutes of LHC Hardware Commissioning

Global overview ?!?

Interface to be further studied & finalised !!!



Layout UX45, top view

ACS

QRL

QUI

QURC



Layout UX45, side view

ACS

QUI

QRL

WRL



Cooling capacity (1/3)

Injection NominalMaximu

m operation

Absolute Maximu

mMV/m 2.75 5.5 8.25 11.0

Static W 150

Margin W 25

Dynamic

W 25 100 225

Total W 200 275 400 950

“LHC Design report”, recently completed by AB/RF




Chamonix XIII 2004 / UW0

2

4

6

8

10

12

14

16

18

Comparing loads and capacities (1)Static

4.5 - 20 K

1.8 K

50 - 75 K20 - 300 K

DynamicCalculated load for Nominal operation compared to installed capacity for sector 8-1

Equivalent capacity [kW]Load calculated1997Load calculated2001Installed capacity

71 % surplus44 % surplus

Chamonix 2004, p 252

Equiv

ale

nt

capaci

ty

[kW

]

Some margin left at

Nominal mode

Nominal mode: no need for capacity upgrade




Chamonix XIII 2004 / UW0

2

4

6

8

10

12

14

16

18

Comparing loads and capacities (2)Static 4.5 - 20 K

1.8 K

50 - 75 K20 - 300 K

Dynamic

Calculated load for Ultimate operation compared to installed capacity for sector 8-1

Equivalent capacity [kW]Load calculated1997Load calculated2001Installed capacity

Load seen by1.8 K ref.24% surplus

Load seen by4.5 K ref.14% missing


Equiv

ale

nt

capaci

ty

[kW

]

Lack of capacityof the 4.5 K

Refrigerators

Ultimate mode: obvious needfor capacity

upgrade



Capacity for beam scrubbing


Equiv

ale

nt

capaci

ty

[kW

]

00.511.522.53

Sector 1-2Sector 2-3Sector 3-4Sector 4-5Sector 5-6Sector 6-7Sector 7-8Sector 8-1Sector 1-2Sector 2-3Sector 3-4Sector 4-5Sector 5-6Sector 6-7Sector 7-8Sector 8-1

Load [W/m/aperture]

BS cooling loop loads (other than e-ecloud)Maximum available capacity for e-ecloudLoss of capacity w/r to local limitationW/o Ex-LEP turbine upgradeWith Ex-LEP turbine upgrade

450 GeV and Nominal Beam IntensityTurbine upgrade decided in 2004, (contract F529)

Cooling capacity in line with hydraulic capacity of beam

screens



Pressure stability (1/2)

1000

1100

1200

1300

1400

1500

1600

21-Sep-04 26-Sep-04 1-Oct-04 6-Oct-04 11-Oct-04 16-Oct-04 21-Oct-04 26-Oct-04 31-Oct-04

0

200

400

600

800

1000

1200

+/- 100 mbar

+/- 5 mbar

with an average of 10 quench per day

line D "equivalent" pressure

cavities pressure

Pre

ssur

e [

mba

r] LHe level [m

m]

SM18



Pressure stability (2/2)Request: 1.350 bar ± 15 mbar

Nota: LHe level control at low possible value will increase GHe volume for intrinsic pressure stability

Pre

ssur

e [

mba

r]

SM18

1340

1345

1350

1355

1360

25-Sep-04 26-Sep-04

+/- 5 mbar

7 quench 15 quench

cavities pressure

Try with Line D (60m3) as buffer and return valve in QUI for Pressure control

If not OK, then use return control valve of module for Pressure control



Coupling via return line D (1/3)

During some operating modes, QRL - Line D will be operated at pressures above Cavities Maximum Allowed Working Pressure

Cool-down:

3.5 B to 1.3 B

Sector quench:

6 to 15 B

Warm-up:

1.3 to 3.5 B

2.0 B Safety device

1.550 B Beam Dump

1.500 B High Voltage off

1.450 B RF off

1.350 B Nominal value




Normal cooldown of a LHC sector

300-4.5 K

Start of ACS and DFBs cooldown

Initial ramp: dTmax* < 75 K

* max temp. difference across magnet


LHC Project Workshop, Session 6 - Chamonix January, 21 2004 G. Riddone, AT Department

+ 2 d to 1.9K

Cool-down of ACS to be started

when QRL- line D pressure is low

enough

Compatible with overall schedule




Industrial cryogenic check-valve installed in refrigerators, DFB’s



Conditioning & tests requirements

Commissioning or conditioning:– After installation before beam:6 months– After yearly warm-up to 300 K: 1

week– After a short stop (T ≤ 50 K): 1-2 hours

Not critical, even if frequent quenches at the beginning

Could be a good idea, but not yet the baseline !!!

Repeated request:– “Need to have the possibility of doing RF

work if machine is down for some time (magnet replacement, …)”



Simplified cooling scheme

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)

Warm recovery line (≤300 K; ≤1.1 bar)

4.5 KRefrigerator

QUI

QRL

SC CavitiesSafety SystemFall-back for

“low intensity”

HP

MP

LP

WarmCompressor

Station

ColdBox

Safety System

Back flow limitation

Open points:• Interface valves located in QRL Service Module• Safety system (control valve, safety valve, bursting disc)

• Back flow limitation



Alternative cooling schemes, why?

To provide the possibility to discharge helium gas at a lower pressure than nominal 1.350 bar, increasing availability of sc cavities operation

To keep availability at least as it is now

While reviewing possible options, why not giving the possibility to operate the sc cavities independently from the sectors



4.5 KRefrigerator

QUI

QRL

SC Cavities

Coupler cooling

HP

MP

LP

WarmCompressor

Station

ColdBox

?

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)


Safety System

Safety System

Option 1: Warm returnAdvantage:• (Cool-down) / Warm-up even if line D > 1.4 bar• Recovery of ACS static losses after sector quench• Allows short period of operation if line D > 1.4 bar

Rather easily implemented



Layout UX45, side view

ACSQRL

WRL

Detailed integration study needed to confirm the concept

Warm Recovery Line (WRL) always along

QRL



Option 2: Cold returnAdvantage:• Cool-down / Warm-up even if line D > 1.4 bar• Recovery of ACS static losses after sector quench• Allows quick re-connection after quench• Allows short period of operation if line D > 1.4 bar• Allows operation independently from QRL / Magnets

4.5 KRefrigerator

QUI

QRL

SC Cavities

Coupler cooling

HP

MP

LP

WarmCompressor

Station

ColdBox

?

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)


Safety System

Safety System

Kept as back-up ?

Disadvantage:• New valve box & lines• Intervention on 2 lines• Not easily implemented

supply &



Layout UX45, top view

ACS

QRL

QUI

QPLB - QULA: Lines between refrigerators & QUI

Additional lines as by-pass of QUI, via a valve boxFeasibility to be confirmedDetailed integration study needed to confirm the concept



Option 3: “Process wish”Advantage:• Cool-down / Warm-up : no limitation• No limitation due to quench•Allows operation independent from QRL / Magnets

4.5 KRefrigerator

QUI

QRL

SC Cavities

Coupler cooling

HP

MP

LP

WarmCompressor

Station

ColdBox

To be defined

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)


Safety System

Safety System

Kept as back-up ?

Disadvantage:• Not likely to be possible



Option 4: Dedicated compressor

Advantage:• Cool-down / Warm-up : no limitation• No limitation due to quench• Operation independent from sector

4.5 KRefrigerator

QUI

QRL

SC Cavities

Coupler cooling

HP

MP

LP

WarmCompressor

Station

ColdBox

DedicatedcompressorCapacity boost

to be defined

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)

Safety System

Safety System

Kept as back-up ?

Disadvantage:• Coupling with 4.5K Ref. not certain if possible



Option 5: Dedicated Ref. (at last!)

Advantage:• Cool-down / Warm-up : no limitation• No limitation due to quench• Operation independent from sector

DedicatedCompressor

DedicatedCold Box

4.5 KRefrigerator

QUI

QRL

SC Cavities

Coupler cooling

HP

MP

LP

WarmCompressor

Station

ColdBox

Kept as back-up ?

C (4.5 K; 3.0 bar)

D (20 K; 1.3 bar)

Safety System

Safety System

Disadvantage:• Where and how to install this now ?



Layout UX45, top view (5)

ACS

QRL

Cooling capacity critical for ultimate beams, something will have to be done !

Integration study needed surface-shaft-cavern



Summary options

Warm Return

Cold sup/ret

“process wish”

Dedicated Compressor

Dedicated Refrigerator

Now 1 2 3 4 5

Pro/consPressure in QRL-D

Minimum decouplin

g

RF more indenp.t Feasibility ?!?

Capacity RF indep.t

Budget (approx.)

100 - 150

kCHF

1 - 2 MCHF

3 - 5 MCHF

Time to install

6 - 10 months

1 - 2 years

2 - 3 years

Data provided as indications, to be further studied if necessary



Summary The reference solution needs to be implemented, with

simple adaptations (control & check valves) to prevent perturbation due to back pressure from line D

A back-up return via the warm recovery line would prevent from major pressure excursions above 1.5 barOption

1

Option

2,3,4, 5

Option5

Any alternative cooling scheme will need a modification of the corresponding cryogenic distribution line (after concerned service module)

Additional capacity will be triggered by needs for ultimate beams or (bad!) operational experience



Acknowledgements

The authors would like to thank all colleagues who contributed to this work:

E. Ciapala, R. Losito, P. Maesen, O. Brunner

Y. MuttoniL. Serio, G. Riddone, L. Tavian

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Cryogenic system in P4: Possible options

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