techniques and diagnostics for the reliability, maintainability and ...€¦ · luigi serio cern 4...

Techniques and diagnostics for the reliability, maintainability and safety of large cryogenic systems:

state-of-the-art and perspectivesLuigi SERIO

14th IMEKO TC10 WorkshopMilan, June 2016Technology Department

Outline

Luigi SERIO CERN 3

IntroductionCryogenics and superconductivityDevices and technologiesReliability, availability and safetyFurther developmentsConclusions

14th IMEKO TC10 Workshop, Milan, June 2016

Outline

Luigi SERIO CERN 4



Introduction

14th IMEKO TC10 Workshop, Milan, June 2016 Luigi SERIO CERN 5

Cryogenic systems for particle physics and thermonuclearfusion superconducting applications are: Large Distribution of kWs of cooling power over several km

Complex Millions of components to monitor and control

Continuous processes Running 24h/24h – 365 day year uninterrupted

Operation requires adequate techniques, diagnostics andinstrumentation to achieve the highest levels of availabilityrequired by multibillion investment research programs

Outline

Luigi SERIO CERN 6



7

cryogenics, that branch of physics whichdeals with the production of very lowtemperatures and their effects on matter

Oxford English Dictionary

2nd edition, Oxford University Press (1989)

cryogenics, the science and technology oftemperatures below 120 K

New International Dictionary of Refrigeration

3rd edition, IIF-IIR Paris (1975)

Temperature in Celsius (C): unit defined with 0 C (ice) and 100 C (vapour)

Temperature in Kelvin (K): 1 K = 1 C, but 0 K = -273.15 C (absolut zero)

14th IMEKO TC10 Workshop, Milan, June 2016 Luigi SERIO CERN

8

Useful range of cryogens, and potential applications

0 20 40 60 80 100 120 140 160 180

Oxygen

Argon

Nitrogen

Neon

Hydrogen

Helium

T [K]

Below PatmAbove Patm

Low temperature sc (LTS)

Nb-Ti Nb3Sn MgB2 YBCO Bi-2223

High temperature sc (HTS)


The “Claude” or “Von Linde” cycle



H. KammerlighOnnes liquefiesOxygen (1894) Helium (1908)

Karol Olszewski and Zygmunt Wróblewskiair, nitrogen, oxygen liquefaction in 1883


1845-1888

1846-1915

Jagiellonian University, Cracow, Poland

~102 of components

Equipment of H. Kamerlingh Onnes (1908)first liquefaction of Helium


Leiden « cascade » to produce liquid hydrogen

Helium liquefaction stage

~103 of components

First HeliumLiquefier

Onnes and van der Waals (1913)

LHC and ITER cryogenic systems


106 - 107 of components

Complex processes requiring high levels of reliability, availability, maintanability and safety

Development of techniques, diagnostics and instrumentation

14

Cooling of superconducting devices

LHC Accelerator

ITER Reactor

Power cables

medical imaging


Basic components of particle acceleratorsand fusion devices


Role of superconductivity and cryogenics in accelerators and fusion devices

Compactness and high fields Superconducting magnets and acceleration cavities

Saving Energy Power consumption (only cryogenics) independent of the magnetic field

Electrical consumption per unit length reduced by a factor 10

Transport current efficiently over long distances High Temperature Superconductor with low thermal conductivity

Power consumption (inclusive of cryogenics) reduced by a factor 3

Efficient vacuum insulation Cryoabsorption and cryocondensation / machinery free devices


Outline

Luigi SERIO CERN 17



Particle accelerators



The CERN Flagship: The Large Hadron Collider (LHC)

LHC accelerator(24 km of superconducting magnets operating at 1.9 K)

ATLAS detector

CMS detector


Highlights of a Remarkable Year : 2012 30 fb-1


The specifications of manysystems were over the state ofthe art. Long R&D programswith many institutes andindustries worldwide werenecessary.

The technological challenges of the LHC

the largest superconducting magnet system ~10’000 magnets

the highest field dipole accelerator magnets 8.3 T

the largest 1.9 K cryogenics installation

superfluid helium, 150 tons of LHe to cool down 37’000 tons ofStSt

ultra-high cryogenic vacuum for the particle beams

10-13 atm, ten times lower than on the Moon

the highest currents controlled with high precision up to 13 kA

the highest precision ever demanded from the power converters

ppm level over several orders of magnitude

a sophisticated and ultra-reliable quench detection and magnet protection system

energy stored in the magnets ~10 GJ,

energy stored in the beams > 700 MJ


Pt 3

Pt 4

Pt 5

Pt 6

Pt 7

Pt 8

Pt 1

Pt 2

Pt 1.8

Cryoplant DistributionPresent Version

Cryogenic plant

LHC cryogenic system

LHC

8 sectorsUpper

Cold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box

Distribution Line Distribution Line

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

ColdCompressor

box

Shaf

tSu

rface

Cav

ern

Tunn

el

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

UnitWarm

CompressorStation

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



ColdCompressor

box

UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



ColdCompressor

box

Shaf

tSu

rface

Cav

ern

Tunn

el


1.8 KRefrigeration

Unit

New4.5 K

Refrigerator

Existing4.5 K

Refrigerator

1.8 KRefrigeration

UnitWarm

CompressorStation

WarmCompressor

Station

WarmCompressor

Station

ColdCompressor

box



UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



ColdCompressor

box

UpperCold Box

Cold Box

WarmCompressor

Station

LowerCold Box


ColdCompressor

box

Shaf

tSu

rface

Cav

ern

Tunn

el


1.8 KRefrigeration

Unit

New4.5 K

Refrigerator

Existing4.5 K

Refrigerator

1.8 KRefrigeration

UnitWarm

CompressorStation

WarmCompressor

Station

WarmCompressor

Station

ColdCompressor

box



UpperCold Box

Interconnection Box

Cold Box

WarmCompressor

Station

LowerCold Box



ColdCompressor

box

Total 8 sectors:Warm Compressors: 64Turbines: 74Cold Comp.: 28Leads: 1’200I/O signals: 60’000PID loops: 4’000

23

Compressor stationof LHC 18 kW@ 4.5 K helium refrigerator

MotorsOil/Helium Coolers Compressors

4.2MW input powerBldg: 15m x 25m


24

LHC 18 kW @ 4.5 K helium cryoplants

Diameter: 4 mLength: 20 mWeigth: 100 tons600 Input/Output signals

Air Liquide Linde

33 kW @ 50 K to 75 K, 23 kW @ 4.6 K to 20 K, 41 g/s liquefaction


Centre: 15,000,000º CSurface:

6,000º C

The sun fuel compressed by G Hydrogen is "burned" to form He

Thermonuclear Fusion reactors

1026 W, 10 mW/m3

5.108 W, 500 kW/m3

neutronfusionD

T He

Lithium (laptop battery) plus a bathtub of water produces 200’000 kWh of electricity45 liters of water + 0.5 kg of Lithium = 40 t of coal

neutron + Li T + He

14.1 MeV

3.5 MeV


The Core of ITER

Toroidal Field CoilNb3Sn, 18, wedged

Central SolenoidNb3Sn, 6 modules

Poloidal Field CoilNb-Ti, 6

Vacuum Vessel9 sectors

Port Plugheating/current drive,

test blanketslimiters/RHdiagnostics

Cryostat24 m high x 28 m dia.

Blanket440 modules

Torus Cryopumps, 8

Major plasma radius 6.2 m

Plasma Volume: 840 m3

Plasma Current: 15 MA

Typical Density: 1020 m-3

Typical Temperature: 20 keV

Fusion Power: 500 MWMachine mass: 23350 t (cryostat + VV + magnets)

- shielding, divertor and manifolds: 7945 t + 1060 port plugs- magnet systems: 10150 t; cryostat: 820 t

Divertor54 cassettes


Plant bridge

Tokamak (11)

The Cryogenic system


Cryogenic instrumentation


Courtesy Ch Balle.

Complexity of flow distribution: e.g the LHC


Beam tube 1Beam tube 2

(4.6 K, 3 bar)

(20 K, 1.3 bar)

(75 K, 19 bar)

(4 K, 16 mbar)

(50 K, 20 bar)

D Q DD D Q DD D Q

Header C

Header D

Header B

Header F

Header E

Line N, Bus-Bars

T

T

T

T

T

T T

X

T

TY Y

T

T

T

L

T

T

X

T

PP

PP

T

T T

P

X

P

T

TT T T T T T T T T

YY Y Y Y Y Y Y Y Y

Beam screen

Support Posts

Warm Instrumentation

Under Evaluation

Cryogenic Instrumentation, vacuum type

X Cryogenic Instrumentation, insertion type

MAGNETSCryogenic Distribution Line

L: Liquid Helim LevelP: PressureT: TemperatureY: Electrical Heater

Type "A" Service Module Type "B" Service Module

L L

HX HX

FT: Flowmeter

FT FT


Instrumentation: Turn-key procurementSensors, actuators, electronics, etc. what is available from industry

Courtesy J Casas.


Instrumentation: Requirements

• Most measurement requirements can be satisfied by standard industrial apparatus

• However some applications require specific developments:• Modified instrument for cryo-operation (e.g.: Coriolis mass flowmeters)• Temperature measurement concerns:

• Platinum thermometers without an “official” conversion below 72 KClass A ± 0.3 K @ 73 KSensors with little literature concerning accuracy (e.g.: CLTS)

• Long term drift

• Specificity of radiation environment and remote diagnostics

• Actual measurement performance difficult to assess


Instrumentation: LHC thermometry

LHC temperature readout is of “laboratory” quality in spite:• Very hostile environment, worse than typical industrial installation• Sheer quantity of measuring channels (9’000) • Individual calibration => require QA during manufacturing• Once installed difficult/impossible to exchange

Cross-check possible for superfluid pressurized bath => dispersion within ± 0.005 K

Courtesy J Casas.


Instrumentation: CERN thermal anchoringMost challenging LHC measurement channel is temperature:

• Superconducting magnet temperature is a key control parameter• Accuracy has a direct impact in regulation band

• Accuracy budget is 0.01 K split in the sensor & electronics

Temperature sensors followed a very strict selection and QA procedureThermal anchoring compatible with large series production was designed to provide

calibration in “final” conditions & provide reliable measurement under vacuum.

Courtesy J Casas.

Temperature sensors


Courtesy Ch Balle.

Pressure sensors


Courtesy Ch Balle.

Level sensors


Courtesy Ch Balle.

Flow sensors


Pressure drop

Thermal

CoriolisPositive displacement Other flow properties

Venturi flow rate meter Designed and constructed following ISO 5167 Measuring pressure drop with a DP-10 Valydine cold

pressure sensor (diaphragm) Accuracies below 3 % with calibration at exact operating

conditions Issues: Zeroing and drift Maintanace Reliability


Courtesy Rivetti et al.

Turbine magnetically levitated Rotor made of YBCO and magnetically levitated below 100 K (Meissner effect)

Stronger forces are obtained permitting high angular speed

A highly axi-symmetric magnet and accurate positioning are required

Angular speed measured by the passive distortion of the originally toroidal shape of themagnetic field generated by the rotor.


A positioning system hold the rotorin the right position untilsuperconductive

Eliminating contact and thereforefriction, the K factor of the turbineis much more stable Higher repeatability and accuracy

In industrial conditions it proved tobe unreliable Courtesy Rivetti et al.

Coriolis flowmeter

Two electromagnetic sensor

Manifold that splits the flowinto two parallel tubes

Transmitter (up to 1 km distance)outside the cryostat

Sensing element (inside the cryostat)


Coriolis flowmeter principle of operation Start the flow and observe the twisting of the tube The fluid momentum coupled with the oscillatory motion created by the

vibration induces a Coriolis force The higher the flow, the greater the twist due to the Coriolis effect


Coriolis performances

CMF025 (6 mm size, 140 g/s f.s.) Coriolis flowmeter:

relative deviation and calculated pressure drop vs. mass flow



Instrumentation: Radiation DesignRadiation maps required to set experimental qualification dosesLHC case:• Cold devices need to be rad-hard• Electronics can be “radtol” (< 1 kGy) if placed at centre & below the dipoles.• Long straight areas: radiation far too high => electronics in protected areas=> Use as much radtol electronics to save cable cost

44

4 x 30 PLC’s4 x 15’000 I/O

8 x 500 PID loops



Dynamic process simulationsModel each cryo

component individually + fluid properties

Build your complete model by assembling elementary components

+ Parametrize each component with your specifications (pipe diameter, valve size, etc.)

Simulate

Include basic control in model OR: couple it to real control system

Define boundary conditions over timeEach refrigeration system10’000 Algebraic equations1’000 Differential EquationsSimulation speed: x3 – x80

Courtesy B. Bradu


CERN: Control improvements Control improvements using simulations Rotating machinery

Control loops regulations Linear and non linear

Comparison of different control techniques for the LHC beam screen temperature control during beam injection (B. Bradu, ICEC, 2016)

Slow PI Fast PI + FF IMC+FF

Comparison of different control techniques for the LHC P6 warm compression station pressures (B. Bradu, Aussois 2012) Comparison of different PID tunings for the output temperature regulation of GreC


ITER: handling of large pulsed loads

Cryoplants + Distribution + Magnets cooling Cryoplant validation under pulsed heat loads

Analysis of parallel cryoplants operation

Evolution of the refrigeration power provided by the three refrigerators(L. Gomez, ICEC, 2014)

Variation of heat load to Cryoplant in the case of plasma disruption (R . Maekawa, Cryogenics, 2014)

Outline

Luigi SERIO CERN 48




Criticality analysis of the Cryogenic System

Courtesy J Martin.


Functional analysis of the Cryogenic System

Courtesy J Martin.


Criticality analysis of the Cryogenic Process

Courtesy J Martin.


Criticality determination

Courtesy J Martin.

Availability improvement by design/operation mitigation

Initial criticality matrix Revised criticality matrix

He turbines

He circulatorsHe CompressorsOil circulators

N2 turboexpenders

(86 failure modes)

Initial criticality matrix Revised criticality matrix Ball bearings, AMB

coils, AMB controllers, statoriccoils, rotor & binding band and VFD electronics.

CRM shaft failure. Erroneous design

or manufacturing of cryolines.

(141 failure modes)

C = O x S


Effective maintenance program Computer Aided Maintenance Management System Infor EAM™ Assets inventory and management Maintenance Procedures and documentation management Spare parts analysis and management Work management, control and optimization via KPIs

Partnership with industry to perform the preventive and corrective maintenance



Preliminary

Overall availability

Courtesy G Ferlin.

56

Safety

Major risks associated with cryogenic fluids at low temperatures:

Asphyxia: Oxygen is replaced by helium Cold burns: in case of contact with cold surfaces Explosion: pressure rise in case of warm-up at

constant volume (1l Liq≈ 700 l gas) Confinement: pressure rise in case of warm-up at

constant volume (1l Liq≈ 700 l gas) make itdifficult to contain a potentially contaminated fluid

Embrittlement: Thermal contractions, potentialfragile at cold


Definition, identification and location of the process nodes

Analysis of the potential failures and hazards

Determination of credible incidents

Analysis of potential causes and consequences

Remedial actions and/or mitigation of consequences

Main stages of the risk and safety analysis


Main cryogenic transfer lines

Helium and nitrogen liquefiersin the cryoplant buildings

Cryodistributionlines and boxes in the tokamak building

Criticality rate of the failure

failure occurence rate(based on probability data and

numer of components)

PM SEVSEVOCCCRT 2

severity rate to the machine(based on the location of defected element)

severity rate to the personnel(based on oxygen deficiency hazard)


Personnel access restrictions

Outline

Luigi SERIO CERN 59



Caloric measurement


Courtesy of Weka AG and KIT

Virtual flow rate meters Infer mass flow from the on-line measurement of valve opening, pressure drop, density measurement

Tested, calibrated and validated on CERN installations Used in the LHC for on-line measurement with about 20 % accuracy Improvement of the metrological performance (presently

RMSE ~ 7 %) by means of uncertainty analysis.



Superconducting radio frequency cavities - imperfections

- Loss of superconductivity by exceeding critical surface: temperature, current, magnetic field,- The ac electromagnetic field causes heat dissipation at the normal conducting spot (defect),

=> can lead to a propagating quench.

Pictures courtesy of: S. Horvath-Mikulas, CERN BE/RF-SRF

1 mm 1 mm

- Stored energy of an acceleration cavity is in the range of 100 J.- Duration of a quench is typically in the range of milliseconds.- Typical defects are usually significantly smaller than 1 mm.

Q>10 kW/cm2.

Courtesy Torsten Koettig


He II – Oscillating Superleak Transducers (OST)

Detection and localization of quench spots on superconductingRF cavities by the measurement of the second sound propagation

OST 1

OST 2

time

time

20 m

m

Courtesy Torsten Koettig


Dynamic simulations During the design phase Validation of dynamic behaviour

Setup of control schemes

During the commissioning phase Virtual commissioning

Tuning of control loops

During the operation phase Operator training

Control improvements

Cryoplant optimization


Root cause analysis and systems dependencies Review topology of intersystem networks Identify clearly and univocally functional dependencies Simulate the global functional network and physical interconnection Provide tools to easily identify interdependencies to assess technical interventions

feasibility and extent Improve availability for machine operation time by Adapting the topology Reducing intervention time Optimizating the protection parameters

Impact on Physics

Duration of No Beam

Fault Duration

Fault Root Cause

System

Sub‐System

Equipment Code

Failure Mode

Equipment Viewpoint

Operations Viewpoint

Cause1

Cause3

Cause5

Cause7

Cause2

Cause4

Cause6

Cause8Cause9Cause10

0 5 10 15 20 25 30Time [hours]

Outline

Luigi SERIO CERN 66



Conclusions


Significant efforts have been made over the years to develop instrumentationand techniques for large & complex cryogenic systems

This has lead to the improvement of the reliability, maintainability and safety ofthe systems and the increase in performances

Today large and complex systems are running at or above design target atCERN and are planned to operate in the coming years at ITER

The LHC cryogenic system istargeting an all inclusive 98%availability goal to ensure recordluminosity for the physics program

Techniques and instrumentationdeveloped for basic scienceapplications are now available forindustrial applications


Something went bump in the nightBy ATLAS Collaboration, 16th June 2016

The observed and expected 95% confidence level (CL) limits on the cross-section times branching ratio to diboson final states for the Heavy Vector Triplet (W', Z') scenario, compared to the theoretical predictions for the HVT model-A (red line) and model-B (purple line). (Image: ATLAS Experiment/CERN)

With many valuable contributions from colleagues at CERN and ITER Organizations

techniques and diagnostics for the reliability, maintainability and ...€¦ · luigi serio cern 4...

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