From about 08:00 to 15:00
See Doug's previous entry for quench recovery details.
First the system had been set to // cold return mode because the solenoid
temps seemed low enough. Temps started to rise instead of cooling so system
was eventually set back to // warm return mode. With the system in // warm
return mode the solenoid was still warming instead of cooling. Solenoid
temps were rising to almost 50K and T1 shield heater was about 90%. T1
inlet temp was below 75K and falling even with shield heat set so high.
CV155 kept closed and // warm return flows were full flow. T1 brake valve
seemed way too open at about 0.8 (compared to previous runs).
15:00 to 19:00
Tried opening CV155, didn't seem to help much. Temps still trending
upwards. Decided to reduce flow to solenoid to see if the cold box would
cool down. Started reducing the // warm return outlet valves. TI121 began
to drop slowly. On graph plotting solenoid temps they started to trend
downwards. Weird. A reduced flow seemed to produce more cooling ? Don't
understand this but will continue. Flow temps returning from solenoid were
about the same temp as TI121, about 35 K. Switching to // cold return mode
to try to reduce TI121. Keeping CV155 as open as possible, just keeping
CV204 from closing completely. After switching to // cold return TI121
starts to slowly fall, T1 inlet temp rises over time so start to drop
shield heater setting. Solenoid temps now trending downwards. Cracked open
CV142 to get some flow going through powerleads. Raised compressor
discharge press to about 11.2 barA. Shield heater down over time to about
10%. Reduced CV155 down to the point where temps almost stop falling then
open cv155 just enogh to keep temps falling.
19:30 Solenoid temps down to about 28K. Letting system continue cooling
overnight.
Guessing the cause of the turbine overspeed quench was caused by
contamination entering the spinning turbine, causing rapid speed changes or
possibly the continued saga of the water damaged Jaquet turbine speed
tachometer giving random false trips. |