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”

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. zhangzhuo@ihep.ac.cn

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 1-2.1 GeV(2.3GeV) 􀂃 Optimized beam energy 1.89 GeV 􀂃 Luminosity 1×1033 cm-2s-1 @1.89 GeV 􀂃 Full energy injection 1-1.89 GeV(2.3GeV) 􀂉 Synchrotron radiation 􀂃 Beam energy 2.5 GeV 􀂃 Beam current 250 mA 􀂃 Keep the existing beam lines unchanged BEPC means Beijing Electron Positron Collider Racket Bird view zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn

Flowchart for SC magnets cryogenic system As u can see. zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn

Layout of SC magnets cryogenic system zhangzhuo@ihep.ac.cn

Interfaces of control system zhangzhuo@ihep.ac.cn

Flowchart for SC cavities cryogenic system zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn

Layout of SC Cavity cryogenic system zhangzhuo@ihep.ac.cn

Interfaces of control system This interface of control system is made through EPICS by IHEP zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn 13

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 zhangzhuo@ihep.ac.cn

Over 100 maintenance projects maintenance in every summer shutdown zhangzhuo@ihep.ac.cn

Maintenance Compressor zhangzhuo@ihep.ac.cn

Maintenance Frequency converter Capacitance zhangzhuo@ihep.ac.cn

Maintenance Oil filter zhangzhuo@ihep.ac.cn

Maintenance Active carbon zhangzhuo@ihep.ac.cn

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

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) zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn

Upgrade Liquid nitrogen sub-system Since 2010,there has been no problem with Add Non-return valve Add a evaporator Add nitrogen filter zhangzhuo@ihep.ac.cn

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

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） zhangzhuo@ihep.ac.cn

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. zhangzhuo@ihep.ac.cn

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 ≥99.9995% Operation Full-automation Cubic metre zhangzhuo@ihep.ac.cn

Upgrade Helium recovery and purification system (2016) zhangzhuo@ihep.ac.cn

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)] zhangzhuo@ihep.ac.cn

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 zhangzhuo@ihep.ac.cn

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 ) zhangzhuo@ihep.ac.cn