Training LHC Powering Luigi Serio CRYOGENICS AND POWERING L. Serio AT/ACR

Training LHC Powering Luigi Serio

CRYOGENICS AND POWERING

L. Serio

AT/ACR

2Training LHC Powering Luigi Serio

Contents

• Cryogenic system introduction

• What does the cryogenic system need to do its job?

• Conditions to start powering: CRYO_START

• When do we have to stop powering: CRYO_MAINTAIN

• Quench and quench recovery

• How operators get an overview of the cryo process

• What instrumentation is available to understand quenches?


LHC Cryogenic system operation

• 8 sectors

• 8 refrigerators

• 8 cold compressor systems

• Cold interconnecting boxes (QUI [8], QURC[8])

• 25 km of cryostats in superfluid helium

• 1400 control loops for c.l. control [powering]

• 320 control loops for magnets T control [powering/beam]

• 600 control loops for beam screen T control [beam]

• few 1000’s control loops for cryo operation


LHC cryogenic system layout

UpperCold Box

Cold Box

WarmCompressor

Station

LowerCold Box

Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS

ColdCompressor

box

Sh

aft

Su

rfa

ceC

ave

rnT

un

ne

l

LHC Sector (3.3 km) LHC Sector (3.3 km)

1.8 KRefrigeration

Unit

New4.5 K

Refrigerator

Existing4.5 K

Refrigerator

1.8 KRefrigeration

Unit

WarmCompressor

Station

WarmCompressor

Station

WarmCompressor

Station

ColdCompressor

box

Even pointOdd point Odd point

MP StorageMP Storage MP Storage

UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box

Distribution Line Distribution Line

Magnet Cryostats, DFB, ACS Magnet Cryostats, DFB, ACS

ColdCompressor

box


LHC Cryogenic Components in Tunnel

4 circuits:

• The cooling and filling circuit : Line C and D

• The thermal shield circuit : Line E and F (no control valves for the standard cell, line E pass across the ARC)

• The cold support and beam screen circuit : Line C and D

• The superfluid helium circuit: line C and B


LHC magnets cooling scheme


Tunnel components cooled by the cryogenic system

Q

Q D DQ D DQDFBMH DFBAN Q D DQ D D D DDD D QQD D DDD D QQD

D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD

D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD

D DDD D QQD D DDD D QQD

Q6DFSM

Q7 Q9 Q11 Q13

Q15 Q17 Q19 Q21 Q23 Q25

Q27 Q29 Q31 Q33R Q33L

Q31 Q29 Q27 Q25 Q23 Q21

Q19 Q17 Q15 Q13

QQQ3

QQ1Q2

DFBXGDD1

DQQ4 D2

DFBMAQDFBMC

Q5

QQ6

DFBAO

DFSMDDD QQD

Q11

DDD D QQQ7Q9

D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD

D DDD D QQD D DDD D QQD D DDD D QQD D DDD D QQD

CRYO-CELL 11_13 R7CRYO-CELL 7_9 R7

CRYO-CELL 15_17 R7 CRYO-CELL 19_21 R7 CRYO-CELL 23_25 R7

CRYO-CELL 27_29 R7 CRYO-CELL 31 R7_33 L8

CRYO-CELL 31_29 L8 CRYO-CELL 27_25 L8 CRYO-CELL 23_21 L8

CRYO-CELL 19_17 L8 CRYO-CELL 15_13 L8

CRYO-CELL 11_9 + Q7 L8

Sector 7-8

LHCb

08R7 09R7 10R7 11R7 12R7 13R7 14R7 15R7

16R7 17R7 18R7 19R7 20R7 21R7 22R7 23R7 24R7 25R7 26R7 27R7

28R7 29R7 30R7 31R7 32R7 33R7 34R7 34L8 33L8 32L8

31L8 30L8 29L8 28L8 27L8 26L8 25L8 24L8 23L8 22L8 21L8 20L8

19L8 18L8 17L8 16L8 15L8 14L8 13L8 12L8

11L8 10L8 09L8 08L8 07L8 06L8 05L8 04L8 03L8 02L8

01

L8

07R706R7

VACSEC.A7R7.M VACSEC.A11R7.M

VACSEC.A15R7.M VACSEC.A19R7.M VACSEC.A23R7.M

VACSEC.A27R7.M VACSEC.A31R7.M VACSEC.A31L8.M

VACSEC.A27L8.M VACSEC.A23L8.M VACSEC.A19L8.M

VACSEC.A15L8.M VACSEC.A11L8.M

VACSEC.A7L8.M VACSEC.A1L8.MVACSEC.A5L8.M VACSEC.A4L8.MVACSEC.A6L8.M

VACSEC.A6R7.M

P8

P7

CRYO. :

ELEC. :

MagnetVAC. :


Cooling towers

Compressed air

Vacuum10-3 mbar

Cooling and ventilation600 m3/h of water

Helium and nitrogen15 t of He – 0.5 MCHF

1260 t of LN2 – 0.2 MCHF

Electric powerabout 4 MW; 3 GWh/month

150 kCHF/month

What does each sector cryogenic system need?

CRYO Controls:Networks, fieldbuses, PLC, SCADA


Systemstopped

ColdStand-by

Warm-up4.5 K-300 K

80 Kstand-by

Cool-down1.9 K

LHe FillingMagnet

Emptying

Cool-down300 K-4.5 K

Quenchrecovery

CRYO Start = 1

NormalOperation

Prepare forpowering

Poweringauthorisation

CRYO Maintain = 0

Cool down Mode

State diagram and cryogenic system process

Powering:

Change toTT891=50K


CRYO_START (authorization for powering) considerations

• The CRYO_START is a start interlock. Therefore once the conditions are met the powering is authorised without any further acknowledgement. It requires a manual intervention (operator request) by the cryogenic operator. It will also modify the control temperature of the HTS leads.

• The CRYO_START ensures that the required conditions to power the magnets are met.

• It gives sufficient margins to “safely” operate cryogenic equipment (temperatures, pressures, levels).

• It does not protect equipment (it does not replace the quench protection system, the voltage taps, the beam monitors, etc.).

• If the CRYO_START disappears the machine can still safely run for several minutes.


CRYO_MAINTAIN (request for slow discharge)

• The CRYO_MAINTAIN is a full stop interlock which cause a slow discharge. An operator acknowledgement is therefore needed to be able to power again the magnets.

• Only the conditions that will directly and rapidly provoke a quench (magnets, current leads, bus-bars) will be considered.

• A filtering logic on the sensor used for CRYO_MAINTAIN will be necessary in order to avoid unnecessary downtime due to failing sensors or electrical noise. In principle it will be based on the verification of 2 out of 3 sensors in the cell requesting the discharge or in the case of only 2 sensors both must be out; the conditions must be valid for at least 30 sec. Instrumentation clearly not functioning (open or short circuit) will be flagged out.


Cryogenics conditions for powering

There would be three logic states:

• Conditions to authorize magnet powering

(CRYO_START=TRUE and CRYO_MAINTAIN=TRUE)

• Conditions that do not authorize magnet powering but if there is already current in the magnets there is no request for discharge (the conditions of magnet powering were met at the time of the start of powering but have disappeared meanwhile) (CRYO_START=FALSE and CRYO_MAINTAIN=TRUE)

• Conditions that do not authorise magnet powering and request a slow current discharge

(CRYO_START=FALSE and CRYO_MAINTAIN=FALSE)

Each powering subsector has one CRYO_START and one CRYO_MAINTAIN


CRYO_START (authorization for powering if TRUE)

1. Superconducting magnets OK• Magnets below threshold (1.95 K) and pressure above threshold (1 bar)• Stand alone above threshold (level above threshold)• Beam screen temperature below 25 K

2. Line D (T lowest point above 5 K) and Quench Tanks empty (pressure)

3. DFB’s OK• Liquid helium level between thresholds in DFB (to cover LTS-HTS joint and below

maximum level)• Current leads temperature between threshold (48 K – 52 K)

4. DSL OK: temperature below threshold (5.2 K)

5. Sector refrigerators OK (Cryoplant Ok for powering)• Compressors• Cold compressors• Turbines• Phase separator above 50 %

6. Ethernet communication OK

7. Vacuum OK (Magnets and QRL): pressure below threshold (10-3 mbar)


CRYO_MAINTAIN (request for slow discharge if FALSE)

1. Magnets below temperature threshold or above liquid helium level (2 K or minimum level for stand alone)

2. Liquid helium level inside thresholds in DFB (above LTS-HTS joint or below maximum level)

3. Current leads temperature below threshold (60 K)

4. DSL temperature below threshold (5.6 K)


Quench and helium recovery


Quench propagation within two adjacent cellMore than 14 cells or full sector recovery up to 48 hours

1 2 3

Number of cells [-]

Cooldown 4.5-1.9 K

Filling 70-100 %

Filling 0-70 %

Cooldown 30-4.5 K

Expected performances and limitations: cell quench recovery

1 2 3

0

1

2

3

4

5

6

7

1 2 3

Recovery time [hours]

< 3 kA 9 kA > x > 3 kA > 9 kA




Expected interfaces and interactions

1. Machine setting-up and performance improvement• Strong reciprocal relationship between the magnets powering and cryogenics

• Magnet powering requires accurate preparation of the cryogenic system and constant monitoring during ramping to avoid operational quenches

2. Machine reliability and availability• Monitoring, control, recovery actions coordinated with magnet powering for reciprocal

optimization and increased availability• Monitoring, control, recovery actions coordinated with technical infrastructures for start-up and

recovery optimization

Cryogenics

InsulationVacuum

Cryostat Insulation

Network

controls

Technical utilities(water, compressed air, electricity)

Compressors, turbines, valves,

instrumentation …

Magnet powering and protection

Quenches

Ramping Losses

Resistive Splices

Temperature control

BeamVacuum

Cryo-pumping

E-cloud losses

Beam

Particle Losses

Image Currents

Synchrotron radiation


Available instrumentation

Cryo CellCryo CellStandard CellStandard CellStandard CellStandard Cell

LTTT TT TT TT TT TT TT TT TT TT TT TT

PT

TT TT

LT

TT PT

TT PT

TT

TTTT TT TT

Positive Slope

PT

Mid Sector


Documentation / informations

LHC Design Report – Chapter 11 - Cryogenics

LHC-Q-ES-0004 (EDMS 710799): The circuit of the LHC cryogenic system

LHC-Q-ES-0003 (EDMS 710797): Functional analysis of the LHC cryogenic system process

http://lhc-cfawg.web.cern.ch/lhc-cfawg/

http://hcc.web.cern.ch/hcc/cryogenics/cryo_systems.php

http://hcc.web.cern.ch/hcc/cryogenics/cryo_magnets.php

http://hcc.web.cern.ch/hcc/cryogenics/cryo_dfbs.php

Documents

Training LHC Powering Luigi Serio CRYOGENICS AND POWERING L. Serio AT/ACR