Instrument Air Flashcards
What is the purpose of the instrument air system?
Provides continuous supply of filter, dry, oil free air at pressure up to 125psig for pneumatic instrument operation and control of pneumatic actuators
What is the purpose of the Service air system?
Supplies oil free air at 125 psig to service air stations for tools, resin transfer and refueling machine manual operation
How can I identify that a pneumatically operated valve has a safety function that may be required to operate to ensure a safe shutdown of the plant following and accident?
It will have a safety related back up air receiver
The instrument air system has how many air compressors and what type are they?
three 100% capacity rotary screw type
Where do the instrument air compressors draw air from and what pressure do they compress to?
Drawn from turbine building air and compress to 105-123psig
What is significant about IAA-UV-2? When will it close?
DC powered solenoid that controls IA into containment
Closes on CSAS 8.5 psig in containment
What is the backup to IA and when will it align?
Nitrogen and aligns when IA header pressure drops below 85psig
What powers the IA compressor motors?
NG 480VAC
What powers the compressor motor space heaters?
NH 480 VAC
What does PK system do for IA?
power to the containment isolation valve IAA-UV-2
What system cools the IA compressors?
TC
What valve opens to admit low pressure nitrogen into the IA header?
PV-52
IA sends compressed air to the fuel pool cooling system for what purpose?
Gate seals
How does IA system interact with Extraction steam and Drain system?
Supplies the ARDVs (air relay dump valves) for bleeder air valve operation.
On a turbine trip, the ARDVs close to depress the line and allow the BTV air cylinders to fully stroke close within 2 seconds
Why is the air inlet control valve minimally opened?
To maintain separator sump pressure
Why is coolant (oil) sprayed into the airend?
Act as an air seal
lube the bearings
remove heat from the air compressor
When does the coolant stop solenoid open and close?
Opens when the compressor starts and closes when the compressor stops
What is the motive force for the coolant?
Separator tank pressure normally at 60psig
The temp control valve regulates the TC water flow thru the coolant cooler to maintain coolant outlet temp to what temp?
120F
What is the purpose of the IA compressor inlet air filters?
Removes particulate materials and minimize compressor water
What size particles can the compressor inlet air filters remove and how effective are they?
3 microns or larger and 99.9% effective
When the compressor is loaded, what should the inlet filter DP reading be?
less than .7 psi
The local controller on the air compressor uses PT-4 inlet vacuum information for what purpose?
Confirm drive motor is rotating in the correct direction on start
Indicate the condition of the inlet air filter
Provide logic for positioning the inlet valve during unloaded operation based on coolant (oil) injection temp and separator pressure
During compressor start up, why is the IA compressor air inlet control valve closed?
It allows the compressor to start with minimal current
Allows the compressor to check proper rotation by checking inlet vacuum is at least 1 psi within 2 seconds
How is the IA compressor inlet control valve controlled?
Controlled by the intellysis controller with the stepper motor
During loaded operation, if the plant air pressure drops below online pressure set poing of 109 psig. What would I expect to occur as a result?
Intellisys/stepper motor opens the inlet valve and closes the blowdown valve.
Compressor will then operate to deliver full capacity air to the plant system
During unloaded operation, how will the system respond if plant air pressure rises to offline setpoint of 119psig?
The inlet valve will nearly close, blowdown valve will open.
Compressor will operate at minimum power
Inlet valve stays slightly open to maintain proper sump pressure to ensure positive coolant (oil) flow and smooth, quiet operation
When the injected coolant temp is less than 120F, what would I expect the separator (sump) pressure to be maintained at?
What about above 120F?
45-50psig
24-33psig
What is the purpose of the IA compressor rotary screw airend?
Compresses the air to 105-123psig
What are the single stage rotary compressor rated for?
571 CFM and 125psig
Describe oil cooling utilized in the rotary compressor
Oil bath compressor that has oil supplied to the inlet of the compressor for lubrication, cooling and compressor sealing