03/08/2017 Coordination Meeting
Purpose
This is a periodic meeting the Cryogenics Group has with various representatives on site to discuss future plans or issues related to supporting cryogenic loads at the accelerator, Halls, and the Testlab.
Attendance
Creel, Wright, Schleeper, Fair, Kashy, Bridza, Kepple, Gomez, Oren, Freyberger, Wood
Agenda and Notes
The purpose of this particular meeting is to discuss the loads on the ESR due to Halls A, B, and C to determine the users plans and identify opportunities to reduce the load on the ESR plant which is operating above its capacity and requiring the support of the CHL/ESR transferline. The extended purpose is to get physics thinking about the slight possibility that the fall program might require modification based on the predictions made since 2006 that the ESR/CHL might be unable to meet the desires of the modified plan physics designed for Hall A after the ESR2 and Moeller did not happen. At this time cryo believes we might be able to handle the loads if properly managed but we are close to the line we will need to proceed carefully.
2006 Paper was issued stating Hall A Moeller would need to be on ESR2. Hall B and C would be on ESR.
2010 Paper was issued stating without ESR2 Hall A would need to be offline
2015 Alternate proposal was issued for Hall A. Cryo said ESR/CHL would be on the edge but it might make it or it might not depending on the actual 12GeV loads.
2017 Cryo held several meetings indicating the load on ESR was higher than physics predicted and running all three Halls together on the ESR was going to be very close to the maximum possible capacity.
1. ESR History
Plant originally built in 1978 for the LBL ESCAR Project. It operated < 900 hours before being shutdown.
Plant was moved to JLAB and installed in 1994 JLAB to support Hall's A, B, and C. The plant has been in nearly continuous operation for more than 22 years.
2. ESR Capacity and costs
Plant capacity envelope is (1500W at 4.5K) OR (800W at 4.5K PLUS 1200W at 15K)
General rules: ESR loses 1 Watt of 4.5K Refrigeration for every 3 watts of 20K refrigeration used and it loses 150 watts of 4.5K refrigeration for every 1g/s of liquefaction used.
Additional TRANSIENT capacity available from CHL via transferline of up to 10g/s at 4.5K depending on the accelerator loads and the flow through the 2K cold box. As the 2K flow increases the liquefaction capability decreases. Using the transferline at 10g/s also increases the cost for power and LN2 at the CHL. Using the CHL/ESR transferline also has several other effects. First it lowers the availability of CHL. Second when the CHL has problems the transferline must be shutdown which will immediately effect the Halls. Third the recovery times for the Halls will be longer.
3. ESR2 Upgrade
The Cryogenics group has been suggesting the installation of the ESR2 4KW at 4.5K SSC plant for many years. The building was constructed and the cold box placed inside but the real work of designing, installing, and commissioning has slipped several times. This is a multi-year effort to complete this work and requires commitment and funding.
4. Current Issues
At this time, as predicted, the ESR is operating well above its full capacity. The CHL1 is supplying approximately 10-15g/s to ESR via the transferline. The primary 4.5K supply pressure is struggling to stay at 2.7atm with periodic dips to 2.5atm. The normal desired supply pressure should be 3.0-3.2 atm. This situation is due to the apparent higher-than-expected 12GeV magnet loads, the fact that not all the magnets are on cold return yet, the need to keep some lead flows on the ESR compressor system because of testing upsets that would effect the other Halls, and the high back pressure plugging issue with SHMS.
We expect the situation to improve somewhat when Hall C stops training quenches and we can move all magnet lead flows over to the CHL recovery system. This will free up ESR compressor capacity to allow us to increase CHL tranferline flow as loads increase. We also expect the situation to improve if Hall C can correct the back pressure issue with the SHMS and once all of the magnet refrigeration loads are on cold return. Cryo is continuing to investigate all of the options to meet physics goals including the use of the 15K heat exchanger and other potential paths to keep moving forward.
6. Fall Schedule
- Fall Schedule for Halls ABC Media:HallsABC17.jpg
5. Plan Forward
Action Items
1. Fix the Hall C SHMS back pressure issue.
2. Get all the magnets on cold return.
3. Get all of the Hall's lead flows on CHL recovery and off of the ESR compressors to free up ESR compressor capacity so we can increase transferline flow and be able to process the additional gas.
4. Investigate the use of the heat exchanger for supporting 15K target loads.
Action Items Updates and Other Information
1. Hall A,B,C Load Discussion Meeting Minutes Apr 30, 2015 Media:Hall_Loads_Meeting_04302015.pdf
2. Directors Review of Cryogenic Capacity 2010 Media:DirectorsReviewCryogenics.pdf
3. Brindza Review of Cryogenic Load on ESR During 12GeV Era Media:Brindza_ESR_12GeV.pdf
4. 12 GeV Nominal End Station Cryogenic Loads from sscmr Media:sscmr.ppt
5. CLAS 12 SC Mag Rev 9_21_06 Kashy Media:CLAS12SCMag.ppt
6. schedule_20151021 Media:schedule_20151021.pdf
7. 20161027.0_LoadVision Media:20161027.0_LoadVision.pdf
8. 20150430.1_LoadVision Media:20150430.1_LoadVision.pdf
9.
