1. Vishy Ravindranath LCLS-II 2 K Cold Box FDR March 9, 2017
2K Cold Box Process
Vishy Ravindranath
LCLS-II 2 K Cold Box FDR
March 9, 2017

2. Background- 2K Cold Box Design Changes
Outline
Background- 2K Cold Box Design Changes
Impact of Design Changes on 2K Process & Response (2K Process Model) to 2K Cold Box PDR Recommendation
2K Cold Box P&ID Overview
LCLS-II 2 K CBX FDR, Mar 9, 2017

3. Introduction- First Light & Nominal Beam LCLS-II Linac Operation
CRYOPLANT
First Light
Both Linac Strings supported by 1 Cryoplant
Gradient - 14 MV/m
2E10 ≤ Qo ≤ 3E10
2K Cold Box- “High-Flow” Configuration (Max. 2K Mass Flow ~ 200 g/s)
Nominal Beam Operations
2 Cryoplants, One cryoplant / LINAC String
Gradient - 16 MV/m
2E10 ≤ Qo ≤ 3E10
2K Cold Box- “Low-Flow” Configuration (Max. 2K Mass Flow ~ 130 g/s)
Interface Box Functionality:
Connection of the Linac strings to a single cryoplant
Connection of the upstream Linac to CP-1 and downstream Linac to CP-2
Independent cool-down & warm-up of each Linac String
LCLS-II 2 K CBX FDR, Mar 9, 2017

4. 2K Cold Box Design Changes Since PDR (Sept-2016)
Conflat Flanges and Removable Pipe Spool Design - PDR
Current 2K Cold Box Design- FDR
Design Features
JLAB Designed U-Tubes (used in CHL-II plant) with Bayonet Connections used for connecting the 2K return transfer line to the suction of CC1 (high-flow) or suction of CC2 (low-flow)
To bypass CC-6 (high –flow) and CC-1 (low-flow) requires removing the U-tube external to the 2K cold box.
Switching over from High-Flow to Low-Flow does not require working in confined spaces.
Design concerns
High possibility of helium leaks associated with the large-10” flanges.
2. Schedule concerns –Leak testing and qualifying the flanges requires a minimum of 3 months of R&D.
3. Operation concerns- Switching between the High Flow and Low Flow configuration requires removal and reconnecting of large pipe spools in tight confined spaces

5. 2K Cold Box Process Model- PDR Recommendations
Example: Upstream LINAC, E=16 Mv/m, Q0 = 2.7x1010
2K Cold Box Process Model was reviewed during the PDR with the following additional action items
Finding: “The 2K cold box will not have a thermal shield. A heat leak analysis has not been performed for the device”.
Comment: “Verify calculations to determine if heat leak into the first cold compressor justifies a shield.”
Recommendation: “Perform a heat leak analysis on the 2K cold box to ensure that the inlet conditions to the 4.5K cold box can be met.”
LCLS-II 2 K CBX FDR, Mar 9, 2017

6. Response to PDR Comments/Recommendations
The heat leak analysis was performed and documented in “LCLSII-4.8-EN-0804 LCLS-II 2K Cold Box Process Analysis ”
Thermal Shield is not incorporated for the following reasons:
The total heat leak into CC-1 suction line due to conduction and radiation heat load = 11 W
By adding a shield, the maximum heat load that can be eliminated is the radiation component ~ 8 W
CC1 suction temperature increase due to the radiation heat load of 8 W = K
Reduction in the 2K cooling capacity due to the 8 W of heat leak = 0.6 %
The advantage of providing the thermal shield is small
The design complication of incorporating the thermal shield inside the 2K cold box (constrained space) outweighs the small gain in the cooling capacity achieved by adding the thermal shield.

7. Impact of U-Tubes on the Cold Compressor Suction Temperature and Pressure
Increase in CC-1 Suction Temperature- Additional Heat Load
Process Location
Heat Load Component
Heat Load includes 30% design margin [W]
9-1/4” U-Tube
Conduction-
a. Male Bayonet (QTY: 4)
b. Female Bayonet (QTY: 4) 36
Radiation- Jacketed U-Tube 4
Total 40
Change in cold compressor suction conditions:
Maximum increase in suction temperature = 0.1 K
Maximum increase in suction pressure = 1 mbar
Increase in CC-1 Suction Pressure due to U-Tube
LCLS-II 2 K CBX FDR, Mar 9, 2017

8. Impact of U-Tubes on the Cold Compressor Suction Temperature and Pressure
ALAT was asked to check and provide maximum 2K flow allowed for the revised inlet pressure and temperature conditions for the selected cold compressor wheel design.
HIGH-FLOW
LOW-FLOW
LCLS-II 2 K CBX FDR, Mar 9, 2017

9. 2K Cold Compressor Vendor Calculation for the Revised Inlet Conditions
Ref: ALAT’s Doc: C4118-NT-004 (2), “Mechanical & Electrical Design”
Revised Cold Compressor Suction Conditions
The selected cold compressor design can provide the following:
High Flow Configuration
Maximum of 204 g/s
Low Flow Configuration
- Maximum of 130 g/s
LCLS-II 2 K CBX FDR, Mar 9, 2017

10. Calculated 2K Cold Box Suction Conditions for Required 2K LINAC Operating Conditions
a. For LINAC Operation, required 2K cooling capacity (mass flow) to be provided by a single 2K cold box ranges from: 100 g/s to 180 g/s.
b. The LINAC 2K Requirements are well within the 2K Cold Compressor Capacity
LCLS-II 2 K CBX PDR, Sept 27, 2016

11. 2K Cold Compressor Pump Down
Ref: ALAT’s Doc: C4118-NT-004 (2), “Mechanical & Electrical Design”
2K Pump Down Path –High Flow (CC1-CC5)
PDR Recommendation:
“The pump down path being provided by the vendor is a different approach than Jlab, SNS, and FRIB are employing. Consider capturing this in a risk assessment and developing a back up plan in case commissioning proves difficult.”
Response:
1. ALAT has provided a proposed pump down path for the High-Flow and Low-Flow Configurations
2. JLAB will also provide a backup pump down plan based on CHL-II commissioning/operation experiences
2K Pump Down Path –Low Flow (CC2-CC6)
LCLS-II 2 K CBX FDR, Mar 9, 2017

12. 2K Cold Box P&ID To 4.5K CBX Clean up return 2. LHe Dewar
4. Safety Reliefs
3. CC Bypass
Sub-atmospheric pressure He gas from cryomodules returns to the suction of CCs and is compressed from ~ 27 mbar to 1.2 bar in the 2 K coldbox. The compressed gas returns to 4.5K coldbox through an U-tube.
For the test of 2 K CBX with LHe dewar, 4.5K cold vapor from LHe dewar is used to simulate the flow, with a 3 kW heater for controlling the helium temperature in the suction line.
A bypass line for the overall CC train is included for 4.5K standby operation mode and pumping down.
Safety valves are used for the protection of the 2 K coldbox, CC and process piping.
Pressure and temperature measurement are installed at the suction of each CC and on the discharge pipe.
A flow meter is installed in the discharge pipe of CCs for flow measurement and controlling of CC.
The 2K coldbox provides vacuum insulation for the cryogenic part of CCs and the cryogenic process piping.
Clean up and warm up piping are included.
Utility piping (Instrument air, cooling water and guard vacuum) are included.
Guard Vac.
1. 2K RET From LINAC CM
3 atm He
Cooling water
Inst. Air

13. Interfaces –Bayonet Connections
Int No.
Interface
Bayonet Size
Component Pressure Rating [psig]
Operating Temperature
He-501
2K return from Interface Box to CC1 suction
9-1/4”
60.4
4-300
He-502
CC1 discharge to CC2 suction
He-503
2K return from Interface Box to CC2 suction
He-504
CC5 Discharge
5-3/16”
75.1
He-505
CC6 Suction
He-506
CC6 Bypass
He-507
30K return from 2K Cold Box to 4K Cold Box
He-508
4K vapor supply from LHe storage dewar to CC1 suction
3-1/8”
83.2
LCLS-II 2 K CBX FDR, Mar 9, 2017

14. Interfaces Int No. Interface Connection ComponentRating [psig]
Operating Temperature [K]
He-510
Cleanup return
½” pipe weld
150
300
He-511
3 Atm He supply
1” pipe weld
GV-512
Guard vacuum
1” pipe weld
Vacuum-15
IA-513
Instrument air
He-515
Relief Valve Discharge Collector
3” pipe welded 15
4-300
CW-517
Cooling water Supply
2” pipe weld
100
CW-518
Cooling water return
~300
LCLS-II 2 K CBX FDR, Mar 9, 2017

15. 2K Cold Box Control Valves
2K Cold Box consists of six cryogenic control valves:
PV41212 (Cold Compressor Bypass Valve): Back-filling of LINAC and for bypassing the cold compressor during 4.5K Standby mode.
PV41500/41510/41520 (4.5 K supply from Dewar to 2K Cold Box): to test the 2K cold box/compressors
PV41170 & PV41160 (Cold Compressor Discharge valves)
LCLS-II 2 K CBX FDR, Mar 9, 2017

16. 2K Cold Box Control Valves
1. Control Valves are sized in accordance with Flow Equations For Sizing Control Valves - ANSI/ISA (IEC Mod)-2007.
All valves are fail closed, equal percentage, range-ability of 1:100, angle valve body pattern.
The detailed calculations are documented in : Ref: LCLSII-4.8-EN-0802 “LCLS-II Cryoplant Cryogenic Control Valves Sizing”
JLAB will procure the control valves and provide them to the 2K cold box manufacturer
LCLS-II 2 K CBX FDR, Mar 9, 2017

17. 2K Cold Box Venturi Flow-Meters
Flows considered for the sizing are based on CHL-II 2K Cold Compressor Flow Data
The flowmeters are sized in accordance with : “Measurement of Fluid flow by means of pressure differential devices-Part 1: ISO (1991)”.
The detailed calculations are documented in :
“Ref: LCLSII-4.8-EN-0803 LCLS-II Cryoplant Flowmeter Sizing”
JLAB will procure the Flow-Meters and provide them to the 2K cold box manufacturer
280 g/s
CC mass flow
200 g/s
CC5 Discharge Pressure = 1.2 atm
CC5 Discharge Temperature
30 K 6K

18. Utilities 1. Electricity: 480 VAC +/-24V 3 phase – 60Hz +/-1Hz
2. Vacuum guard (For CC and bayonets)
Vacuum will be used for the sealing intercept
3. Instrument air
For 6 pneumatic control valves
Supply pressure of 90 psig
4. Cooling water (For CC and Diffusion Pump)
Maximum inlet temperature : 38°C
Maximum return temperature : 49°C
Maximum flow rate per compressor : 0.75m3/h (3.3 gpm)
Pressure drop: < 1bar
PDR Recommendations: Consider the use of a closed loop water cooling for the turbine, cold compressors and diffusion pump.
Response: There is a secondary closed water loop dedicated for the turbines, cold compressors and diffusion pumps in each cryoplant.
P&ID: , “LCLS-II Cooling Water System (For Turbines & Cold Compressors)”

19. Summary
The cold compressor design accommodates the anticipated variation in the heat load.
The design & interface requirements for the 2.0 K Cold Box have been clearly identified on the P&ID.
PDR Review recommendations have been addressed with further heat load analysis as recommended
Detailed supporting calculation documents been developed:
Document No.
Title
Author
Status
LCLSII-4.8-EN-0802
LCLS-II Cryoplant Cryogenic Control Valves Sizing
V. Ravindranath
Under Review
LCLSII-4.8-EN-0803
LCLS-II Cryoplant Flowmeter Sizing
LCLSII-4.8-EN-0804
LCLS-II 2K Cold Box Process Analysis
Released
2K Cold Box P&ID
JLAB
LCLS-II 2 K CBX FDR, Mar 9, 2017

20. Back-Up
LCLS-II 2 K CBX FDR, Mar 9, 2017

21. LCLS-II Cryomodule Heat Load at 2.0K
REF: (1) Tom’s Excel Spread Sheet: “LCLScryoHeat-23Feb2016-FirstLight.xlsx”
Tables show the “2.0 K Heat Load” (does not include the heat load on Transfer Lines)
The Static Heat Load includes a Design Margin of x 1.30.
The uncertainty in the Dynamic Heat Load is in terms of the Cavity Quality Factor
A. First Light Configuration
E = 14 MV/m, Qo = 2.7E10
E = 14 MV/m, Qo = 2.0E10
E = 14 MV/m, Qo = 3.0E10
Up-stream
Down-Stream
Total
Static [kW]
0.158
0.186
0.344
Dynamic [kW]
1.100
1.200
2.300
1.462
1.608
3.070
0.968
1.083
2.051
Total [kW]
1.258
1.386
2.644
1.620
1.794
3.414
1.126
1.269
2.395
B. Normal Beam Operation
E = 16 MV/m, Qo = 2.7E10
E = 16 MV/m, Qo = 2.0E10
E = 16 MV/m, Qo = 3.0E10
Up-stream
Down-Stream
Total
Static [kW]
0.158
0.186
0.344
Dynamic [kW]
1.415
1.615
3.030
1.878
2.146
4.024
1.261
1.464
2.725
Total [kW]
1.573
1.801
3.374
2.036
2.332
4.368
1.419
1.650
3.069
E = 19 MV/m, Qo = 2.0E10
E = 19 MV/m, Qo = 3.0E10
2.569
2.987
5.556
1.717
2.024
3.741
2.727
3.173
5.900
1.875
2.210
4.085

22. Heat Load on the Transfer Lines- Cryomodule, CDS & Cryoplant
Upstream
Line A: 89 W
Line B: 261 W
Downstream
Line A: 54 W
Line B: 233 W
Heat Load includes a design margin of x 1.3.
Heat Load on the 2.0 K RETURN LINE-B only contributes to raising the inlet temperature cold compressor suction
Ref: LCLSII-4.8-EN-0804 LCLS-II 2K Cold Box Process Analysis