Overview of the ESS Linac CryogenicDistribution System
Jaroslaw Fydrych
Cryodistribution Project Engineer
ESS Cryogenic Safety Workshop, Lund, February 10, 2016
•Introduction
•Layout of Cryogenic Distribution System
•CDS flow scheme and Valve box PIDs
•Cryogenic Distribution Line (CDL) design
•Specification of the CDS safety devices
•Sizing of the CDS safety devices
•Summary
Outline
ESS cryogenic system block diagram
Cryogenic Distribution Line (310 m)
comprising 43 valve boxes
Endbox
Cryogenic
Transfer
Line (65 m)
Splitting
box
Linac CDS – function and layout
21 High BetaCryomodules(174 m)
9 Medium Beta
Cryomodules
(75 m)
13 Spoke
Cryomodules
(54 m)
Linac
Cryoplant
Superconducting section of the Optimus linac (303 m)
Auxiliary process lines
Cryogenic System of the ESS Linac
Layout
Cryogenic Distribution System for the ESS linear accelerator is intended for deliveringthe cooling power from the linac cryoplant to the cryomodules by means of the constantflows of supercritical and cold gaseous helium, at 4.5 K and 40 K, respectively.
Linac CDS – general flow scheme
Two main cryogenic circuits:
- Cold helium circuit (Helium supply line + VLP line)
- Thermal shield circuit (TS supply line + TS return line)
+ 4 auxiliary process lines:
Helium recovery line (cold) HP line (warm)
SV relief line (cold) Purge line (warm)
30 elliptical cryomodules
13 Spoke cryomodules
CDS-ELValve box PID
The heat exchanger,JT and filling valves arein the cryomodule!
Valve boxfor the elliptical cryomodule
30 elliptical cryomodules
13 spoke cryomodules
The heat exchanger,JT and filling valves arein the valve box!
Valve boxfor the spoke cryomodule
30 elliptical cryomodules
13 spoke cryomodules
CDS-SLValve box PID
CDS isometric view
Valve box
Cryoline
Jumperconnection
Auxiliary process
lines
Interconnection
Interface tocryomodule
Interface to the ACCP
Modular structureof the cryogenic
distribution line!
CDS-EL valve box conceptual design
Valve boxfor the ellipticalcryomodule
Valve boxpiping
Sliding supports
of main processlines
Fixed support
of main processlines
Vacuum
barrier
Side process lines
Interface to thecryomodule
Cryogeniccontrolvalves
VLP line
He supplyline
Thermal shieldsupply line
Thermal shieldreturn line
10 layers of MLIon cold process lines
CDS-EL valve box conceptual design– process lines
Cryoline thermalshield
Valve box
thermal shield
Shield
sliding
supports
Bottom plate
(demountable)
Thermal shield
of cryolineinterconnection(demountable)
Thermal shield
at the cryomoduleinterface(demountable)
Jumper connectionthermal shield
30 layers of MLIon thermal shield
CDS-EL valve box conceptual design– thermal shield
Cryoline vacuumjacket (DN550)
Valve box
vacuum jacket
Cryoline
support
Bottom plate
(demountable)
Cryolineinterconnectionsleeve with axialcompensator (DN600)
Interconnection
sleeve at theinterface to thecryomodule
Jumper connectionvacuum jacket
with lateralcompensators
(vertical: DN350horizontal: DN450 )
Valve box
supports
CDS-EL valve box conceptual design– external envelope
Specification of the CDS safety devices
310 m
65 m
Specification of the CDS safety devices
310 m
65 m
Initial sizing (according to EN4126) given in ESS-0011735 (CDS-EL spec) and ESS-0017178 (CDS-SL spec)In-kind Partners requested for verifying the sizing
Specification of the CDS safety devices
310 m
65 m
Requirements given in the CDS specs (ESS-0011735 and ESS-0017178)
Initial sizing (according to EN4126) given in ESS-0011735 (CDS-EL spec) and ESS-0017178 (CDS-SL spec)In-kind Partners requested for verifying the initial sizing
Sizing of the CDS safety devices
on ACCP cold box
on End box
Two failure scenarios
1. Cold process line ruptures 2. Vacuum vessel breaks
on valve
boxes
Sizing of the CDS safety devices
on ACCP cold box
on End box
•VLP line ruptures (Dh = 273 mm)
•Cold helium flows into the vacuum vessel insulation space
•Cold helium absorbs heat from the radiation shieldand external envelope
•Cold helium temperature and pressure increase
•Safety valves SV71 get open
•Cold helium flows to the ESS tunnel
Cold helium flow rate thought 43 SV71 valves(do = 85 mm)
Evolution of pressure in the vacuum jacket
Two failure scenarios
1. Cold process line ruptures 2. Vacuum vessel breaks
43 safetyvalves SV71
do = 85mm
on valve
boxes
Sizing of the CDS safety devices
on ACCP cold box
on End box
•VLP line ruptures (Dh = 273 mm)
•Cold helium flows into the vacuum vessel insulation space
•Cold helium absorbs heat from the radiation shieldand external envelope
•Cold helium temperature and pressure increase
•Safety valves SV71 get open
•Cold helium flows to the ESS tunnel
Cold helium flow rate thought 43 SV71 valves(do = 85 mm)
Evolution of pressure in the vacuum jacket
Two failure scenarios
1. Cold process line ruptures 2. Vacuum vessel breaks
43 safetyvalves SV71
do = 85mm
on valve
boxes
•Vacuum vessel safety valve is accidentally open (human error)
•Air flows into the vacuum space and condenses/solidifies onthe inner cold surfaces
•Cold helium in the process lines absorbs the heat from air
•Pressure in the process line increases
•Process line safety valves get open
•Cold helium flows to the vent lines at the cold box and end box
Evolution of pressure in the TS return line
Cold helium discharge thought SV14 and SV94(do = 20 mm)
SV11 do = 35 mm (> 25 mm)
SV12 do = 14 mm (= 14 mm)
RD12 do = 45 mm (< 85 mm)
SV13 do = 9 mm (< 11mm)
SV14 do = 20 mm (>11mm)
SV91 do = 35 mm
SV92 do = 14 mm
RD92 do = 45 mm
SV93 do = 9 mm
SV94 do = 20 mm
Summary
•The main parts of the Linac CDS are Cryogenic Transfer Line (65 m)and Cryogenic Distribution Line (310 m).
•The cryolines contain 4 cold process lines (2xDN50, DN65 and DN250)and share one common insulation vacuum (375m, DN550).
•Each process line will be protected against excessive pressure by twopressure safety devices located at the line ends.
•The CDS vacuum jacket will be equipped with 43 safety valves locatedon the CDL external envelope.
•Sizing of the CDS pressure safety devices is well advanced but still inprogress.