1. Cryo-ops 2018，Beijing，IHEP
Ten years operation experience and current status of BEPCII cryogenic system
Zhuo Zhang
JUNE 5
Cryo-ops 2018，Beijing，IHEP
Hello, everyone:
My name is zhangzhuo. I work at ihep.
I'm honored and proud to have the opportunity to speak at the workshop.
Today I would like to present my slide “ten years operation experience and current status of BEPCII cryogenic system”

2. Introduction on BEPCII Cryogenic System Operation Availability
Outline
Introduction on BEPCII Cryogenic System
Operation Availability
Maintenance and upgrade
Status and problem
Summary
Let's start with the topics of today's presentation.

3. Introduction on BEPCII Cryogenic system
BEPCII —An upgrade project of BEPC
—A double-ring factory-like machine
—Deliver beams to both HEP & SR
􀂉 Collision
􀂃 Beam energy range GeV(2.3GeV)
􀂃 Optimized beam energy GeV
􀂃 Luminosity ×1033 GeV
􀂃 Full energy injection GeV(2.3GeV)
􀂉 Synchrotron radiation
􀂃 Beam energy GeV
􀂃 Beam current mA
􀂃 Keep the existing beam lines unchanged
BEPC means Beijing Electron Positron Collider
Racket
Bird view

4. Layout of BEPCII cryogenic system
Tank farm
Warm pipe
No.2 Refrigerator
Cryogenic hall
W-SCRF
E-SCRF
BEPCII cryogenic system was constructed during the upgrade of BEPC,.the system has two refrigerators.
The one is for superconducting solenoid magnet (SSM), superconducting insert (SIM) magnets
The another is for superconducting RF cavities (SRFC).
The total refrigeration capacity is about 1 kW/4.5 K.
No.1 Refrigerator
SSM&SIM magnets

5. Flowchart for SC magnets cryogenic system
As u can see.

6. Heat loads of SC magnets cryogenic system
Cryogenic devices
SCQ2
SSM
Cryostat for magnets
152 25
Current leads
0.3g/s2
0.4g/s
Eddy current loss 15
Valve boxes for magnets
92
Cryogenic transfer lines 35 23
1000L Dewar& Valve Box 30
Subcooled heat exchanger 20
Subtotal
211+1g/s
Margin
30%
Total
274.3 W+1.3 g/s

7. Layout of SC magnets cryogenic system

8. Interfaces of control system

9. Flowchart for SC cavities cryogenic system

10. Heat Loads of SC Cavity cryogenic system
SRF static heat load（W）
2×30
Dynamic heat loads
RF loss（W）
2×84
coupler（W）
2×12
Common parts
Distribution valve box（W） 20
Cryogenic transfer lines（W） 24
Helium dewar and heaters（W） 30
Margin 20% （W）
65.2
Total（W）
391.2W

11. Layout of SC Cavity cryogenic system

12. Interfaces of control system
This interface of control system is made through EPICS by IHEP

13. SC RF cavity cryogenic system
Availability (from 2006)
higher than 94.8%
higher than 94.9%
TBF divided by TBF and TTR.
SC magnets cryogenic system
SC RF cavity cryogenic system 13

14. Availability (from 2006) TTR(Time to restoration system) is very long
Find the problem and replace sensor
0.5hour
Time to restoration system
5~6 hour
Pressure sensor PI2150B failure,display 0bara
Replace the pressure sensor
TTR(Time to restoration system) is very long

15. Over 100 maintenance projects
maintenance in every summer shutdown

16. Maintenance
Compressor

17. Maintenance
Frequency converter
Capacitance

18. Maintenance
Oil filter

19. Maintenance
Active carbon

20. Maintenance ECO drain and UPS zhangzhuo@ihep.ac.cn quick-wear part
Battery

21. Upgrade Cooling water sub-system
CHILLED WATER
In this illustration ,Most of the failures are due to cooling water.
Since 2008,there has been no problem with
Helium compressor shut down.( oil temperature>110 degree Celsius )
Turbine shut down. (cooling water flow < 15L/min)

22. Upgrade Liquid nitrogen sub-system zhangzhuo@ihep.ac.cn blocked
80K shield
First heater exchange
nitrogen sub-system failure time accounts for the largest proportion of total failure time.
Nitrogen control valve faile
consumption increase

23. Upgrade Liquid nitrogen sub-system
Since 2010,there has been no problem with
Add Non-return valve Add a evaporator Add nitrogen filter

24. Upgrade Redundant compressor(2011) zhangzhuo@ihep.ac.cn
The redundant compressor modle is same as compressor a and compressor b.

25. Upgrade
The temperature of the first heater exchanger in coldbox is too high
LN,78K
GN,273K
HGHe,300K
LGHe
HGHe,97K ①
GAS N - High pressure H（N side） ① ② ②
Liquid N - High pressure H（H side） ③ ④ ③
GAS N - High pressure H（H side） ④
Liquid N - High pressure H（N side）
This is a complex problem.
Three fluid domains
We might get the same performance but the reason behind it is different. ⑤
Low pressure H - High pressure H（L H side） ⑤ ⑥ ⑥
Low pressure H - High pressure H（H H side）

26. Upgrade
The temperature of the first heater exchanger in coldbox is too high
From 2015, the temperature is stable
Heat insulation on high pressured pipe.

27. Upgrade Helium recovery and purification system (2016) Performance
Helium gas storage
≤20000NM3
Work pressure
≤200bar
 Recovery ability
≥210NM3/h
Purification ability
≥105NM3/h
Purified helium gas
≥ %
Operation
Full-automation
Cubic metre

28. Upgrade Helium recovery and purification system (2016)

29. Status and problem The unknown heater in sc cavity
The E-cavity helium pressure (red) increases with the electron current (green) abnormally.
The unknown heat power is about 80W at the electron current of 750mA.
Change the protection pressure set value. (from 1.26bara to 1.28bara)
Static
ampere['æmpeə(r)]

30. Status and problem The unknown heater in sc cavity
The pressure drop between the supercavity and the dewar is too small, resulting there is not enough liquid helium around the SC cavity.
When the liquid helium level drop to 85%, cryogenic system’s “READY” signal will lost and the RF system will shut down.
Pout~1.275bar
Pin=1.30bar
Percent%
? water injector

31. Summary
From 2006, the BEPCII cryogenic system always run in a high availability.
For any trip or failed, it need long time to restoration the cryogenic system.
Although we maintain and upgrade the system every summer, there are still some new problems can be found next year.
The excessive helium pressure of the SC cavity in the electron ring need more work. (The unknown heater )