ESS Cryogenic System Design

Philipp ArnoldSection Leader Cryogenics

www.europeanspallationsource.se6th Internation Workshop on Cryogenic Operations

November 10-12, 2014

2

View of the Southwest in 2025

• Max IV – a national research facility, under construction, opens up in 2015

• Science City – a new part of town

Lund(113 500)

Malmö(309 000) Copenhagen

(1 200 000)

MAX IV

ESS

3

Outline

1) System Overview

2) Cryogenic Design Choices

– Plant and process arrangement– Cryomodule cooling at 2K– ACCP plant staging– LN2 pre-cooling– Helium storage– Heat recovery– Control system

3) Procurement and Tender Evaluation

(1) ESS Cryogenic System

Pure Helium Gas Storage 1

20 m3 LHe Tank

Standalone Helium Purifier

Helium Recovery System

Pure Helium Gas Storage 2

AcceleratorCryoplant

Test & Instrument Cryoplant

5 m3 LHe Tank

Target ModeratorCryoplant

LHe Mobile Dewars

Test Stand Distribution

System

Instruments & Experiments

LN2 Storage Tanks

LN2 Mobile Dewars

Cryogenic Distribution

System

Cryomodules Cryomodule Test Stand

Target Distribution

System

Hydrogen Circulation Box

Hydrogen Moderator

5

(2.1) Plant and process arrangement

Combination of warm and cold sub-atmospheric compression for ACCP

- High flexibility for load adaption- Optimal overall efficiency

1 coldbox building, 1 compressor building,1 plant per job

- Highest space and CAPEX savings- Schedule, budgeting and technical requirements- Maintainability

Only warm sub-atmospheric compression for TICP

6

(2.2) Cryomodule cooling at 2K

Production of 2 K helium in 2 K heat exchanger and a sub-sequent Joule-Thomson valve in each of the cryomodule–valve box assemblies

- Heat load on CDS only on 4.5K, not 2K helium

- independent warm-up / maintenance / cool-down of single cryomodules while the rest of the system is maintained in cold condition

7

(2.3) ACCP plant staging

Total heat load stage 1

Total heat load stage 2

Static heat load stage 1

Static heat load stage 2

0

500

1000

1500

2000

2500

3000

3500

excl. margin incl. margin

2K H

eat L

oad

[W]

Two sets of flow parts for cold rotating equipment

- turbine expanders

- cold turbo compressors

Variable frequency drive(s) in the warm LP compressor system

8

(2.4) LN2 pre-cooling

TICPWITH LN2 PRE-COOLING

- CM testing: “constant level liquefaction w/o internal freeze-out purification”

- Liquefaction for LHe consumers: “rising level liquefaction w/ internal purification”

- Turbo-expanders can be optimized to perform efficiently in both operation

- Much better plant fit with easy adapting when higher rate needed (switch pre-cooling on)

ACCP WITHOUT LN2 PRE-COOLING

- ~80% of the load is at 2K with cold compression translated to 4-20K refrigeration

- ~20 tons of cold mass max do not impose tough cool-down requirements

- No substantial CAPEX impact

- Downsides of LN2 usage like dependency on regular supply and increased traffic at ESS more severe

9

(2.5) Helium Storage

12

3

(1) Helium inventory in CMs and CDS ~ 2 tons during normal operation

(2) 20 m3 LHe tank as second fill– Speed up re-cool-down

– Facilitate helium management in transient modes

(3) 16 x 60 m3 warm tanks – Store helium when accelerator warm

– A little more required for warm parts of ACCP and higher helium inventory during 4.5K standby mode / cool-down

NO CD0

500

1000

1500

2000

2500

Helium mass in CMs & CDS w/o shield[kg]

Vapour He-lium

Liquid He-lium

10

(2.6) Heat Recovery

• No elevated oil or helium temperatures out of compressor suppliers specs

• Dedicated cooling water circuit for cryoplant (quality constraints of available cooling water in the building)

• Slow temperature control on cooling water side, fast temperature control on oil side

• Cooler design state of the art e.g. for Kaeser compressors

• Cooling function has priority over heat recovery return

Compr. motor

Middle temperature

Return

Middle temperature

Supply

Oil vessel

Helium compressor

Helium cooler

Oil cooler

He to fine oil removal

He from cold box

High temperature

Return

Middle temperature

Return

25C

25C

27C

27C

27C

39C

85C

85C90C

32C

90C

32C

83C

37C

11

(2.7) Control System

Safe operation even in case the EPICS IOC shuts down

ACCP control system is compatible with the other linac control

Advantages of an open control system

Functional split between local PLCs and EPICS IOC

• Deterministic control loops • Time critical and internal functions• Safety functions

• Supervisory controls • High level batch operations• HMI incl. local SCADA• Alarm handling • Data archiving

12

(3) How do we get what we want?

Procurement procedures open, restricted, negotiated, competitive dialogue

Scope split clear interfaces (also during different phases of installation)

complex systems (rather one integrator) vs. simple systems

Small yet relevant qualitative part in the tender evaluation verifiable with proposal

Thorough acceptance testing Possibly incentive part for consumption

Sincere and transparent procurement process

Thank you for your attention