Hydrogen Water Chemistry Flashcards
What are the 3 flow paths to the plant for hydrogen?
- 250 psig supply from 6 gas storage tubes charged to 1000 to 2000 psig from liquid H2 tank
- 100 psig supply directly from H2 tank when normal flow path < 100 psig
- 90 psig from 3 reserves 2000 psig gas storage tubes if first two paths are < 90 psig
How much pressure does each oxygen train maintain?
Subsystem A —- 110 psig Oxygen
Subsystem B —- 100 psig
What are the 3 types of HWC trips?
Normal Shutdown
H2 immediate trip with Normal O2 shutdown
Emergency trips
How does the normal shutdown trip shutdown?
ramps down slowly by INFI-90
How does the H2 immediate trip with Normal O2 shutdown, shutdown?
H2 isolates immediately
O2 ramps down, then isolates
How does the Emergency trip shutdown?
H2/)2 flow stops immediately
What is Nitrogen used for in this system?
pneumatic valves, purge panels to minimize fire hazards
what flow rate is H2 maintained at?
15-20 scfm @ 100% power
linear to O2
What flow rate is O2 maintained at?
7.5-10 scfm @ 100% power
linear to H2
When will excess flow valve auto close for Hydrogen?
> 200 scfm
when will excess flow valve auto close for Oxygen?
> 153 scfm
When would the excess flow valve need to be bypassed?
when a large amount will be needed.
example, filling generator with H2 on startup
What is the power supply to the H2/O2 storage systems?
site power loop subsystem J
What powers the logic for the H2/O2 storage system?
1Y99
Why is O2 injected into Offgas?
scavenge hydrogen injected into feedwater to prevent explosion in offgas system. it is inserted into offgas at/before the catalytic recombiners
Where is oxygen injected at?
Condensate pump suction
Why is oxygen injected?
to protect the oxide layer in condensate/feedwater piping
Where is hydrogen injected at?
Condensate booster pump bypass line
Why is hydrogen injected?
reduce free O2 in Rx minimizing Intergranular Stress Corrosion Cracking (IGSCC) of stainless components inside Rx
What are the conditions that cause Hydrogen Immediate Trip with Normal Oxygen Shutdown?
Signal failure
hydrogen detected in Area 1, 113’ by any one of four h2
detectors
CBP bypass flow < 50 gpm
Offgas Oxygen concentration < 6% (both channels)
Offgas hydrogen concentration > 2% (both channels)
Both offgas H2 analyzers OOSVC
INFI-90 H2 controller failure
H2 flow transmitter P73-R003 failure
What are the conditions that cause an EMERGENCY TRIP?
** One’s you’re likely to see on test **
BOTH SJAE SUCTION VALVES F003 FULL CLOSED
OFFGAS ISOLATION VALVE F060 NOT FULL OPEN
LOSS OF POWER
(less likely to see on test)
HWC emergency trip HS in trip
HWC system shutdown pushbutton held 5 seconds
INFI-90 oxygen controller failure
oxygen flow transmitter p73-R004 failed
offgas oxygen concentration > 39% (both channels)
one offgas o2 analyzer channel in “high trip” with the
other o2 analyzer in “low trip”
Rx water level of 15” or 50”
