Condensate Pipelines

[Yomahuta]

I have two 100% capacity gland seal fans extracting non-condensable gases/steam from the gland steam condenser (for steam turbine's gland seal steam) installed with NRVs downstream of fans. One of the fans showed normal current, its NRV showed no abnormal sound, but the NRV's downstream line remained relatively colder suggesting water/condensate depositing within the line common after both NRV's of these two fans. I want to solve this problem regarding installing a drain valve at common line after NRV, replace NRV with Y-strainer, or simply install a new NRV. Currently I follow the routine of draining the fan bodies periodically. Is there anything I'm missing on?

 

[LittleInch]

Maybe it's me but I'm not quite following what your issue is.

A diagram of physically how these are laid out would help.

does only fan work at the same time?
Is the flow going round in a circle?
What are the pressure here and why are there syphon traps?
what's that little flag symbol? An open vent?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

suggesting water/condensate depositing within the line common after both NRV's of these two fans

For this suggestion, do you check the flow meters of BR401, BR402 and BR403, and confirm that only one fan, either #1 or #2 fan, is running? And, how much colder than the U/S pipe temperature (at T801) of the fan?

 

[georgeverghese]

The liquid seal line may be blocked at the U bend on the exit for the other extraction fan - have you tried blowing the dirt out of this U trap ? These NRVs' are not shown on this dwg by the way.

 

[stgrme]

Please note that all drains shown on the piping diagram should be from low points in each pipe segment/run. If not, the drains need to be moved to the low points. The piping diagram already shows a drain from the common line downstream of NRVs with a sealing loop, I don’t think you need to add a drain valve.

If water is collecting on the suction side of the fan bodies, I would suggest adding continuous drains from each fan body to the vapor space (above the water level) in the Gland Steam Condenser (GSC).

For clarification of the piping diagram, please provide descriptions and final destinations for connections “F” and “VI” on the GSC.

If the water level in the GSC is controlled by a drainer or trap, you may need a vent from the drainer/trap to the vapor space in the GSC to get the drainer/trap to work correctly.

Best of luck!

 

[Yomahuta]

I have the H42H-40 type NRVs installed. The loop seal is okay. The drain if installed after the NRV can drain the liquid but the liquid column just above the NRV might be keeping NRV to lift up, resultingly the recirculation of flow within the fan increasing the local temperature of fan. WHAT SHALL I GO ABOUT NOW?

 

[georgeverghese]

NRV should not be installed in the vertical pipe or tubing run with flow going up. Condensate will leak past check valve in reverse direction back into fan body.