[Hallb-engineering] [Esr-users] [New Logentry] Hall B Torus and DBX Nitrogen System

[David Kashy]

Hi Chris,
Let us know if we need to re-implement it or if you want us to try something else.
As I've explained before to some on this list, the Hall B LN2 usage is generally quite low and the supply transferline slopes downhill to the Hall. The TL batch fills because the boil off fills the transferline with gas. So the concept of taking more should in general smooth our flow but if it has not worked, then we would need to go to a higher heater power so that the LN2 subcooling is enough to balance the TL heat load. If the subcooler at ESR could provide more subcooling that would help, but it may not be big enough or maybe the supply is fully sub-cooled so the only choices are to live with the oscillations or to use more in Hall B with the heater.

Thanks for the info!

Dave
________________________________
From: Chris Perry <cperry at jlab.org>
Sent: Tuesday, August 11, 2020 4:05 PM
To: David Kashy <kashy at jlab.org>; esr-users at jlab.org <esr-users at jlab.org>; hallb-engineering at jlab.org <hallb-engineering at jlab.org>; Nicholas Sandoval <sandoval at jlab.org>
Subject: Re: [Esr-users] [New Logentry] Hall B Torus and DBX Nitrogen System

Dave,
   That change was made in an attempt to stabilize nitrogen flow for Hall C, in retrospect it did not appear to give much if any benefit.

-Chris

________________________________
From: Esr-users <esr-users-bounces at jlab.org> on behalf of kashy at jlab.org <kashy at jlab.org>
Sent: Tuesday, August 11, 2020 4:00 PM
To: esr-users at jlab.org <esr-users at jlab.org>; hallb-engineering at jlab.org <hallb-engineering at jlab.org>; Nicholas Sandoval <sandoval at jlab.org>
Subject: [Esr-users] [New Logentry] Hall B Torus and DBX Nitrogen System

Hall B Torus and DBX Nitrogen System<https://logbooks.jlab.org/entry/3825052>

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Lognumber 3825052<https://logbooks.jlab.org/entry/3825052>. Submitted by kashy<https://logbooks.jlab.org/user/kashy> on Tue, 08/11/2020 - 15:56<https://logbooks.jlab.org/entries?start_date=1597172170&end_date=1597179370&book=HBLOG&book=HBTORUS&book=CLOG>.

Logbooks:       HBLOG<https://logbooks.jlab.org/book/hblog> HBTORUS<https://logbooks.jlab.org/book/hbtorus> CLOG<https://logbooks.jlab.org/book/clog>
Entry Makers:   Kashy

During our controls work, I was looking at the cryogenic system. I found that a heater in the LN2 reservoir has been turned on to 30% of full power on ~Jan 9, 2020. There was no record of why in the logbooks and no update of the PID control spreadsheet. The change was done by putting the minimum position for the heater to 30% so I am slowly stepping it back down to 0.

The heater power is 2kW so 30% is 600W or 3g/s of LN2
3g/s is equal to 320 liters/day or 85 gallons/day
Current cost of LN2 is 0.25$/gallon so we were throwing away ~ 20$/day does not sound like much, but since Jan 9 approximately 4600$.

Something to keep in mind!

If the system becomes unstable we may have to review this change, but it worked for years with the heater min at 0...

[https://logbooks.jlab.org/files/styles/plentybig/public/2020/08/3825052/Screenshot%20(85).png]
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