HC review - 12 May 2005Luigi SERIO - AT/ACR/OP1 SECTOR COOL DOWN AND CRYOGENIC COMMISSIONING L. Serio

HC review - 12 May 2005 Luigi SERIO - AT/ACR/OP 1

SECTOR COOL DOWN AND CRYOGENIC COMMISSIONING

L. Serio


Outline

IntroductionWhat are the requirements and constraints before and during the tests

Utilities, fluids, resources, organization, safety

Test program and technical challenges to be addressedOr what we could not test during individual sub-system commissioning and string tests

The expected performances and limitationSteady state, transients and recovery

What happens afterwards …Conclusions


introduction

LHC Test String 1 (45-m long): 1994 – 199812’000 hours operation, 170 quenches, 5 C/WCooldown and commissioning: 2 - 3 months and 2 FTE (+ 4 IS)

QRV and cryogenics flow scheme simplification

LHC Test String 2 (100-m long): 2001 - 20038’000 hours operation, 42 quenches, 3 C/WCooldown and commissioning: 2 months with 2 FTE (+4 IS)

Quench propagation/recovery, superfluid and supercritical helium loop validation

LHC sectors commissioning (2 x 3000-m long): 2006-2007Overall more than 2000 hours/sector, ?, 1 CCooldown and commissioning: 2-3 months with 12 FTE (+18 IS)

Cool down time and cooling flow distribution optimization, superfluid helium loop commissioning and optimization with adjacent cells cooling, cooling power distribution and transient disturbance between individual cooling loops, quench propagation and recovery for more than one cell


ConstraintsPhysics and available cooling power:

cannot cooldown in less than 14.2 days

Safety:Cryogenic fluids

Cold burns – negligible risk (all discharges away from personnel) Asphyxia – negligible risk

Need oxygen deficiency monitoring installed and commissioned

Radiation (activation of dust, impurities, helium [tritium]) No concern for sector test and machine start-up but radiation protection monitoring and

sampling system should be installed for long term assessment prior to first injection test Missing equipments/systems

Avoid cooldown with missing components, otherwise: Always ensure buffer and inert volume between process and air

Access No access during pressure tests No access (restricted?) during first cooldown (SG constraint?) Restricted access during subsequent cooldown and magnets filling No access with magnet powering above 3 kA ?


Cooling towers

Compressed air

Vacuum10-3 mbar

Cooling and ventilation600 m3/h of water

Helium and nitrogen12 t of He; extra storage by end of 2006!

1300 t of LN2 (a 20 t cont. every 4 hours)

Electric powerabout 4 MW; 25 GWh/year

Requirements (per sector)

CRYO Controls&instr.:

Networks, fieldbuses, PLC, SCADA, process control software, instrumentation

CRYO OK

Total peak power up to 18 MW


Equipment to be monitored/controlled (per cryogenic island [2 sectors]):2 x 4.5 K refrigerator; 2 x 1.8 K refrigeration unit; 1 interconnection box2 x 3 km cryogenic distribution line; about 50 cryo systems

(this is comparable in size to the all LEP cryo system but more complex)Resources:

Conditioning/leak/pressure testing: 1 x 8; assistance vacuum group1 Technical responsible; 2 operators (IS)

Cooldown and cryogenic commissioning: 1 x 8; on-call service1 Engineer in Charge; 2 Techn. resp.; 4 operators (IS)

Powering: 2 x 8 shift; on-call service on 3rd shift1 EiC; 4 Techn. Resp.; 8 operators (IS)

Total for 13 months planning: 3 EiC; 9 Techn. Resp.; 18 operators (IS)

Resources for cryo commissioning

!!! 2 x 8 shift for powering does not correspond to 2 x 8 shift for cryo !!!

10 weeks from start of cooldown to CRYO OK for powering 2 weeks in parallel with powering tests for fine tuning with

current and quench recovery

!!! Time for conditioning/cleaning QRL and magnets not taken into account !!!


Preparatory (ongoing) work (Cryogenic Functional Analysis WG): SCOPE: Define the functional analysis of the LHC cryogenic

system and establish the corresponding logic and documentationThe FA must be defined to first maximize the system availability and secondly minimize the operating cost

Establish detailed and global Process and Flow diagramsDefine the cryogenic system overall processIdentify possible flaws in global processProduce global process control logicSpecify supervision and monitoring viewProduce functional analysis of the cryogenic system for the LHC sectors commissioning and operation


Cryo sub-systems commissioning strategy

Individual components and sub-systems are manufactured in industryPreliminary qualification is performed – for some sub-systems - in dedicated tests facilitiesAfter delivery and installation at CERN each sub-systems is individually commissioned and qualified for operationThe commissioned and qualified sub-systems are then used in a cascade way to commission dependent sub-systemsEach sub-systems is individually controlled and it exchanges main status parameters for connection disconnection with slave and master sub-systems for interlock and start-upThe collective behavior of the cryogenic sub-systems is progressively tested and the overall process established


Cryogenic subsystems commissioning

“New 4.5K” refrigerators: all commissioned ready for operation

“Ex-LEP” refrigerators:major overhauling and adaptation for LHC in 2005-06commissioningready for operation

QUI:installation and commissioning 2005consolidations required (filter system, heater, controls)ready for operation

1.8 K refrigeration units: installation and commissioning 2005-06ready for operation

Cryogenic distribution line:installation and partial commissioning (first 1.2 sectors)no functional tests at working temperature on components and instrumentationpressure and leak testswould require commissioning and flushing of circuits to avoid contamination (1 additional week needed)

Arc magnets, DFB’s, RF cavities, DSL, standalone magnets, inner tripletspressure and leak testswould require commissioning and flushing of circuits to avoid contamination (1 additional week needed)

Global systemOverall collective behavior assessment and validationControl loops fine tuning and sub-system information exchange for start/stop/interlockControl process logic commissioning and validation


Technical challenges still to be addressed: Overall cryogenic commissioning

Magnets string and DFB’s instrumentation commissioningMagnets string, DFB’s and RF cavities commissioningQRL commissioningLogistics for fluids (liquid nitrogen and helium) for a full sectorOverall collective behavior of systems (new from string):

Cool down time and cooling flow distribution optimizationSuperfluid helium loop commissioning and optimization with adjacent cells coolingCooling power distribution and transient disturbance between individual cooling loopsQuench propagation and recovery for more than one cell

Establish and validate interlocks and process for sub-systems collective behavior

String experience + Cryogenic Functional Analysis WG


90 K

commissioning of cryogenics

1 Tests at warm

3 Cooldown 300 K to 90 K

4 Cooldown 90 K to 4.5 K and filling

5 Cooldown 4.5 K to 1.9 K

Conditioning of cryogenic circuits

B1

Leak and pressure tests of all the cryogenic circuits

A2check consistency of PLC and supervision database, verify instrument chain from supervision to sensor

Verification of sector instrumentation and controls

Verification of cryoplant instrumentation and controls

A1

Nominal conditions on thermal screens

Start 1.9 K refrigeratorsPumpdown of line B

Operation at nominal temperature (1.9 K) 6

Tuning of all active control loopsFlow distribution and cooldown optimization

E

Verification of nominal temperatures, pressures and flows –tuning of individual loops dynamics – verification of process control logic and stability

H

D Wait 10-2 mbar

2 Pumping of insulation vacuum

Start compressor station

B2C

Open JT-valves for cooldown

F

293 K

4.5 K

CRYO OK

G


Theoretical cooldown of a LHC sector

Start of ACS and DFBs cooldown

300-4.5 K


Final cooldown to 1.9 K

1.5

2

2.5

3

3.5

4

4.5

5

0 10 20 30 40

Time [hour]

Cold

-mass t

em

pera

ture

[K

]

Normal operation

Fast operation

Once at 4.5 K and after verification of equipments, systems and process control logic, launch the final steps:

•start of 1.8 K refrigeration unit, •pumpdown of line B, •filling and cooldown 4.5-1.9 K

Theoretically 2 additional days once cooling flow distribution, PID tuning, sensors troubleshooting, process control logic, collective system behaviour, are assessed and validated.

Filling

Cooldown4.5-1.9K


1.7

1.75

1.8

1.85

1.9

1.95

2

10:50 11:00 11:10 11:20 11:30 11:40

0

2

4

6

8

10

12[kA], W/m[K]

0.4 W/m 0.5 W/m - 0.6 nOhm

1.7

1.75

1.8

1.85

1.9

1.95

2

04:48 09:36 14:24 19:12 00:00 04:48 09:36 14:24

0

2000

4000

6000

8000

10000

12000

magnets temperatures (inlet/outlet)

current all circuits [A]

saturation temperature

change in control setpoint

Expected performances and limitations:Magnets temperature control (more than 30 control loops/sector)


temperature control of current leads

0

10

20

30

40

50

60

70

9:07

9:21

9:36

9:50

10:0

410

:19

10:3

310

:48

time

Te

mp

era

ture

(K)

op

en

ing

(%)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Cu

rre

ntx

10

kA,

flow

(g

/s)

Pre

ssu

re (

ba

r)

Valve opening

Flow

Inlet Pressure

Current12-05-2003

Expected performances and limitations: Operation of HTS current leads and DFB’s

(more than 150 control loops per sector)


Quench propagation limited to 1 cell; several cells or full sector 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:quench recovery

1 2 3

0

1

2

3

4

5

6

7

1 2 3

Recovery time [hours]

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


What could go wrong In principle, the production side of the cryogenic system should have a

low impact (except on sector 2-3) on the commissioning time: Redundancy of systems Available spare cooling capacity Proven reliability with better than 98 % availability on systems

commissioned so far

However, failure of sub-systems and components can not be ruled out completely and could result in few days delays to switch to redundant system or component and to adapt to new configuration

The distribution system (QRL) and the tunnel components would certainly have lower availability as they will be tested for the first time

Worst failure would be the loss of insulation vacuum on the QUI or QRL as well as the refrigerator in point 2 or DFB’s for magnet powering (time to investigate, repair, + recovery time)

Most likely failure would be filters blockage on the QUI during or after the first cool down and magnets quench due to accumulation of impurities (1 day + recovery time) (consolidations under study – allow time for circuits conditioning before cooldown)


Recovery time to nominal operation after a

failure

The cryogenic recovery acts as a time amplifier - utility stop: rec. time=6 hours + 3 x “utility stop length”- bad insulation vacuum or leaking QRV: rec. time = 15 x “utility stop length”

Controls :? Complete new control system ? Ethernet dependent (control loops, PLC

communication) Required performances, reliability and

robustness of the control system is not “yet” up to requirements

Utilities:? Water, compressed air, electricity, … might have

a « big » impact on commissioning time


How time can be saved

Preparation work: documentation, procedures, risk analysis, process control logic definition and

verification prior to cooldown, instrumentation verification at warm, maintenance of equipments and spare parts availability, etc.

It REQUIRES RESOURCES!!!

Extensive testing of subsystems prior to global commissioning (i.e. QRL, DFB)

Ensure that the “experts” that have designed and built the systems are available during commissioning for support and consolidation work

Ensure that the trained IS operators on the ALLS contract are not “disappearing” (physically and mentally) towards the end of their contract (it happens to coincide with the end of the HC!)

Reduce the number of control loops / circuits to be commissioned to the minimum necessary for the first year machine operation (it would have to be done afterwards!)


What happens afterwards

How to leave the sectors:Baseline is: stop cooling and natural warm-up

anyway minimum standard preventive maintenance would be required during SD

If active warm-up at 300 K:additional IS operators and technical staff

If cold standby at 75 K:110 kChF/sector/month (elec. Power) + additional IS operator + fluids, maint., etc. (about 200 kChF/month)

If at nominal temperatures150 kChF/sector/month (elec. Power) + additional IS operator + fluids, maint., etc. (about 400 kChF/month) and 2 CERN Technical staff

PLUS the requirements of additional helium and storage


Conclusions

Cryogenic system overall performances and reliability have been checked during dedicated individual sub-systems and String tests and are under commissioning prior to sectors tests (except for tunnel/sectors components)

Shortcuts during sub-systems and sector commissioning is increasing Commissioning and start-up time

(equipments ready for operation) Reliability of the cryogenic system Training time for operation and maintenance crews

Overall process and collective behavior as well as the process control system performance and robustness need to be assessed and optimized during sectors test

Cryogenic fluids logistics and in particular helium inventory storage needs to be put in place and assessed

Resources: IS operators – use present contract (end 7/2007 !) + up to 11 op Staff – 3 missing

Due to the system complexity and shortcuts on individual systems tests, the validation of commissioning time and required resources estimates can only happen after first sector test

Documents

HC review - 12 May 2005Luigi SERIO - AT/ACR/OP1 SECTOR COOL DOWN AND CRYOGENIC COMMISSIONING L. Serio