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2K Cryogenic System Design for cERL at KEK Contents: • Background and Goal • 2 K Super-fluid Helium • Liquefier vs. Refrigerator • JT-Heat Exchager • High Performance Transfer Line • 2K Cryogenic System for cERL • Summary
KEK Kenji. Hosoyama
scale (cm)
0 5 10 15
Aluminum 80K Shield
Polyester Callor
G-10 Support Plate
G-10 Support Block
Stainless Steel ClipStainless Steel
Stainless Steel
Stainless Steel
Stainless Steel
φ 34
φ14
φ14
φ14
φ14
Screw
LN2 Flow
LN2 Flow
He Flow
He Flow
LN2 Return
LN2 Return
He Return
He Return
φ17.3
φ17.3
φ 28a
b
c
Background and Goal
• We had an old helium refrigerator (TCF200 500W at 4.4K or 250L/h ) got from NIMS (National Institute for Material Science).
• Design, construction and operation of 2K 40W cryogenic system for ILC prototype cryomodule was successfully completed.
For base line design of cERL 2K system, we adopted this. • High performance transfer line system and JT heat exchanger have
been developed by our group at KEK. • cERL 2K cryogenic system; Two 2K refrigerators for injector and main linac. Cooling power of each 2K ref. can increase up to 80W by addition of pump units. Total cooling power can upgrade by adding a new liquefier.
Helium Ref. System for cERL
Injector Linac Main Linac 2K Ref. #1 2K Ref. #2
Multi-transfer Line
Liq. Helium Dewar 3000L Helium Ref. Cold Box
TCF 200 LN2 Circulation System
Medium Pressure Helium Gas Storage
Cooling Tower Screw Type Helium Compressor
Helium Gas Pumping Units
Gas Bag
High Pressure Helium Gas Storage
Purifier
Liq. Nitrogen
Heat Load 10 mA x 5MV 2 K 8 W 4.5K 18 W 80 K 145 W
Heat Load 10 mA x 10 MV x 4 units 2 K 46 W 4.5K 30 W 80 K 191 W Heat Load 100 mA x 10 MV
2 K 31 W 4.5K 94 W 80 K 1000 W
Heat Load 10 mA x 15 MV x 4 units 2 K 102 W 4.5K 30 W 80 K 191 W
100 m3
50 m3
High Pressure Helium Compressor
2 K Super-fluid Helium
Use the latent heat of vaporization of helium Cold Pump Large System CEBAF, LHC, …. Warm Pump Small System KEK
How to make 2K Super-fluid Helium ?
Pres
sure
[bar
]
Saturated Vapor Pressure of Helium
2.0 K
4.4 K
Temperature [K]
0.03 bar
1.2 bar
Gas State
Liquid State
20 J / g
Enth
alpy
[ J /
g ]
Temperature [K] 2.0 K
latent heat of vaporization
Liq. He 1 l 1 / 8 kg 1 / 8 x 20 = 2.5 kJ Lig. He 1 l / hr -- 2.5 / 3.6 = 0.7 W
Cooling Power 1W -- Liq. He Consumption 1.4 l /hr
JT-Heat Exchanger
62 % 89 %
4.2 K
2.2 K
Super-fluid T~ 1.8 K
Normal Helium T~ 4.2 K
JT - Heat Exchanger
JT1
JT2
Pumping (Warm or Cold Pump)
Production ratio of 1.8K liquid helium can increase from 62% to 89% by lowering the temperature of expand liquid helium from 4.2K to 2.2K using the cold vaporized gas through JT-heat exchanger. Because saturated pressure of the 2K helium is very low, i.e. ~ 0.03bar, specially designed heat exchanger is required.
Small DP
2K Ref. & Cryo-module
2K Ref. Cold-box
Cryo-module
Cryo-module
2K Ref. Cold-box
2K J-T Valve
2K Heat Exchanger
2K Liq. He
Liq. Helium Level
2K Liq. He
Gas Helium Pumping
For Cool-down
Gas Helium
Gas Helium
Liq. Helium
Liq. Helium
Conceptual design of cERL 2K cryogenic system Gas Helium Pumping System
Gas Helium
Liq. He 3000 L
He Liq./ Ref. TCF 200 250 L/hr
2K Liq. He
4.4 K Liq. He
2K Cold-box #1
2K J-T Valve
2K Heat Exchanger
Multi-channel Transfer Line
Cryo-module
Gas He
Rotary Pump
Mechanical Booster Pump
2K Liq. Helium
4.4 K
2K cold boxes are installed near by cryo-modules 4K He liq. / ref. ; supply liq. He to the 2K cold boxes and cool the 4K heat loads. 2K cooling; is made by pumping at room temp. Note: 80K thermal shields are not shown. Cold connection
Detailed Design of 2K Cold Box To cool down the cryomodule from room temperature to 2K through 4.2K and to control the 2K liquid helium level constant during RF operation of SC cavity, many control valves are installed.
Heat Exchanger
Conceptual Design of JT Heat Exchanger for Version 2 (2K 30W)
Comment : Version 1 : Lamination Type (1.8 K Magnet Cooling System) Version 2 : Fined Tube Type 1/8 “ (2 K ILC Cavity Cooling System) Version 3 : Fined Tube Type 1/4” (2 K cERL Cooling System)
Cold Return Gas
Cold Return Gas
Liq. Helium In
Liq. Helium Out
SUS 60.5D
Copper 1/8” Pipe
Heat Exchanger fins are brazed to coiled tube
Heat Exchanger Fin made by punching press
Heat Exchanger
Cross-section
Lower pressure drop structure in return line Leak tight: the body made of steel parts and assembled by argon welding
System flow of cERL Cryogenic System
Multi-channel Transfer Line
Helium Ref. TFC 200 Cold Box
Cold Helium Gas Return
Liq. Helium
Liq. Helium Dewar 3000L
4.4 K Pot
4.4 K Pot
2 K Pot
2 K Pot
2K Ref. Cold Box
#1 2K Ref.
Cold Box #2
5K Shield
80K Shield
5K Shield
80K Shield
Pumping Pumping
LN2 LN2
Liquid Nitrogen Circulation System Cold Box
Liquid Nitrogen Screw Compressor 5 bar 30 Nm3/hr
Liq. N2 Helium Compressor
Pumping System
Layout of Cryogenic System
Helium Pumping System /
Gas Bag Helium Ref. Cold Box (TCF200)
Liquid Helium Dewar 3000L
Vertical Cryostats
Purifier
Multi-Transfer Line
Area for Cold Test 10 m x 5 m
2K Ref. #1
Area for Cryogenics 10 m x 20 m
Helium Ref. Cold Box for Upgrade
Liquid Helium Dewar
2K Ref. #2
10 m
10 m
High Performance Transfer Line 1
scale (cm)
0 5 10 15
Aluminum 80K Shield
Polyester Callor
G-10 Support Plate
G-10 Support Block
Stainless Steel ClipStainless Steel
Stainless Steel
Stainless Steel
Stainless Steel
φ 34
φ14
φ14
φ14
φ14
Screw
LN2 Flow
LN2 Flow
He Flow
He Flow
LN2 Return
LN2 Return
He Return
He Return
φ17.3
φ17.3
φ 28a
b
c
Small heat leak to cold helium piping ~ 0.05 W/m 80 K aluminum thermal shield, cooled by liq. nitrogen, intercept the heat leak form the room temperature parts.
Small cold mass --- thin stainless tube (0.5 t ) Stable operation during transient condition, i.e., recovery from the cold helium flow stop.
“Development of a High Performance Transfer Line System” Advances in Cryogenic Engineering Vol. 45, p1395, (2000)
Easy to assembling
Leak tight stainless welding
Good thermal contact Thermal shield is made by extrusion
Sub-transfer 80 K aluminum thermal shield Need liq. nitrogen circulation system
Main Transfer Line Sub Transfer Line
14
High Performance Transfer Line 2
Liq. He Flow Φ18, 0.5t SUS316L
Gas He Return Φ28, 0.5t SUS316L
Liq. N2 Φ14, 0.5t SUS316L
Valve Box 80K Al Thermal Shield
80K Al Shield Φ100, 2t
80K Al Thermal Shield Main Multi-Transfer Line
G10 Support Plate
Main Multi-Transfer Line
By the 80K aluminum thermal shield cooled by liquid nitrogen, the heat leak to helium line can reduce to ~ 0.05 W/m
2K Cryogenic System for cERL 1
2K Ref. 1
2K Ref. 2
Helium Ref. Cold Box
Liq. Helium Dewar 3000L Helium Gas Pumping Units
Multi-transfer Line
Gas Bag
Purifier
2K Cryogenic System for cERL 2
Summary • The cERL 2K cooling system consisted of helium refrigerator
TCF200, two 2K refrigerators with helium gas pumping system and multi-transfer line was proposed and designed in 2008.
• The main components of the system were constructed and installed in the experimental hall of the cERL by the end of FY 2009.
• Before start the new operation of helium refrigerator for cERL, we cleaned up oil in the flow line of the 1st heat exchanger using the solvent and replace the charcoal by new one.
• The commissioning of the helium refrigerator was started in September of 2010.
• The commissioning of the 2K refrigerator and helium transfer line without the cryomodule will be carried out and 2K cooling capacity will be checked very soon.