Towards a DFX Design Concept through - PowerPoint Presentation

Slide1

Towards a DFX Design Concept through Iteration of Ideas

Wendell Bailey, Iole Falorio, Yifeng Yang @ SouthamptonYann Leclercq, Vittorio Parma @ CERN

WP6a

1

Liquid He level

DFX Concept Based on a Horizontal Integration

Presented in April/June 2017

S

ingle continuous 90

o

bend from vertical entry at the shaft to horizontal

DFX divided into sections for sequential assembly while the SC-Link is installed

A large

GHe

space continuous into the inner vessel of SC-Link flexible cryostat

SC-Link bending and insertion handled by special tooling

MgB2

Concrete

Shaft

NbTi

Instru

. wire

Safety relief

Heater

Level gauge

Plug to D1

Possible TS cooling line

Cryo

connection:

Return to SD

Inlet

LHe

Return TS E’H

Liquid level

MgB2-NbTi splices

Integration reservation

DFX Concept Based on a Horizontal Integration

Presented in April/June 2017

Angled entry, 90 degree total bend –

Tooling

Insertion into the a short fulling open end section of DFX

The final bend inside the DFX is achieved by sliding down a straight slope and then swing in to desired shape by articulating the tooling

Necessary

conditionsThe inserted SC-Link section is housed in the flexible inner continuously but without the outer. A temporary cover for integration in the shaft must be removed before insertion.The inner flexible must be pre-perforated at designed location

The extraction of the SC-Link after the system test shall be performed

Reopen/disassemble DFXUsing the tooling and the reverse procedure of insertion

Others ???

Question R

aised :Inserting Rigid of SC-Link Section without Cable Handling:

Alternative Integration?

6

Amalia, 19/07/2018

LHC shaft/core

Components of

SC Link

DFX below LHC Shaft



1.3-1.6

m

DFX Concept

Based on a Vertical Integration

Main Considerations:

Fit within the space constraints

Cryogenic considerations:

Level control

GHe

flow

Cryogenic interfacesEasy assembly within the vertical space under the shaftLTS/LTS splices with a minimum LTS length ahead of the SC-LinkMaintainability

1. DFX in position and fully open, SC-Link lowered from the shaft

2. SC-Link rigid section fixed/welded to DFX lower He vessel

3. LTS/LTS splices completed and DFX lower He vessel closed

4. DFX/SC-Link vacuum barrier in position

5. DFX lower vacuum vessel in position, DFX/SC-Link vacuum membrane welded to the SC-Link rigid top

6. DFX upper vacuum vessel, heater, blow-off/instrumentation outer jackets closed

2. LTS/LTS splices completed and DFX lower He vessel closed

1.5 W/m

↑

0.7 g/s

1.6

m

Reduced

vapour space in the range for level control

A height of 250mm with a diameter of < 300mm

Level control within ±125mm

Additional vapour spaces bluff-off/heater extension

cryolines

(50-100mm ID)

Total cross-section ~ 600cm

2

At a continuous liquid He filling rate of 42ml/s for a nominal SC-Link

GHe

mass flow rate of 5g/s

Takes 180s or 3min to overfill to the 125mm high margin if filled at constant rate if the heater went off

The same length of time required to recover from the overfill or reach the underfill limit if the filling is off

A higher filling rate is needed to recover from underfill

The reduced vapour space seems still sufficient for a reasonable control dynamics even in on/off mode

GHe

flow in the vicinity of MgB2/

NbTi

splices to pass from main bath to the vapour space above

Mitigated by an annulus

Impedance into the splice region needs to be optimised

Disturbance to the liquid level stability: bubbles exit at an effective velocity of ~3.6cm/s at 50% quality

Line SD pressure and the management of excess vapour in DFX

Baseline control strategy for level and

GHe

flow, dynamic characteristics (time constant,

alarms, auxiliary instrumentations

suc

as pressure, etc), and their interplays

MgB2

NbTi

Instru

. wires

Safety relief

Heater

Level gauge

Plug to D1

Possible TS cooling line

Cryo

connection:

Return to SD

Inlet

Lhe

CS

Return TS E’H

2

Liquid level

MgB2-NbTi splices

Integration reservation

Concrete

Shaft

Cryogenic Considerations and Initial Feedback from Cryogenics Group

Points raised by Cryogenics Group

Increase the cross-section of

GHe

and

LHe

interface by factor of 4

Avoid

LHe

volume below the sub-cooled region at D1 plug

1.3 m

A

modest vapour space in the range for level control

A height of 250mm and a diameter of 500mm

Level control within ±125mm

Additional vapour spaces bluff-off/heater extension

cryolines

(50-100mm ID)

Total cross-section ~ 2000cm

2 At a continuous liquid He filling rate of 42ml/s for a nominal SC-Link GHe mass flow rate of 5g/sTakes 595s or ~10min to overfill to the 125mm high margin if filled at constant rate if the heater went offThe same length of time required to recover from the overfill or reach the underfill limit if the filling is offA higher filling rate is needed to recover from underfillThe increased vapour space gives a better control dynamics even in on/off mode GHe flow in the vicinity of MgB2/NbTi splices to pass from main bath to the vapour space aboveMitigated by a large annulus for 228ml/s for GHe generated by the heater withinImpedance into the splice region needs to be optimisedDisturbance to the liquid level stability: bubbles exit at an effective velocity of ~1cm/s at 14% qualityMgB2Plug to D1Liquid levelIntegration reservationConcrete

Shaft

1.6 m

With SC-LINK led by ~

2m

LTS cables for LTS/LTS splice horizontally, it is possible to remove large vertical splice section

Enlarge to SC-Link/LTS annulus to 500mm od to increase the

LHe

volume near the liquid level

Possible to limit the 500mm od section of the annulus to about 500m high if necessary

MgB2-NbTi splices

Iterations to Accommodate Points Raised by Cryogenic Group

14

Revised DFX Concept Based on a Vertical Integration

Points raised by Cryogenics Group

The sacrifice of short LTS cables leads to further simplification for assembly

Only two small welds for the vertical sections in the LHC tunnel

Remove of separate chimneys for heater, instrumentation and burst device

15

Weld 1

Weld 2

Meeting our Android

18

That’s for now, more to do…, but have decide on which concept soon (less than a week?)Thank you for listening