This morning I valved in the "pressure build circuit" on CP4 Dewar (1/2 turn CCW). The Dewar head pressure is now at 17 psig (just a hair below 16 psig on other gauge) and GN2 flow is back up to ~50 scfhx100 (fluctuates between 40-55), up from 12 scfhx100 this morning. More flow means decreased regen temperature and therefore I also increased the variac today in increments: 58%, then 60%. Attached is 8 hr plot of the GN2 regen temperature - both inlet and exhaust.
Leaving pressure build circuit valved in overnight. Will valve out tomorrow morning before LN2 truck delivery.
I watched the GN2 flow surge up to 80 scfhx100, which is too high so I closed the pressure build valve and also lowered the variac to 56% so we don't get alarms all night. Kyle's adjustment on the economizer valve may still be stabilizing and increasing head pressure and tomorrow the Dewar is scheduled for a refill which will also increase flow.
Note that there is a 15 psig pressure relief valve just downstream of the GN2 heater.