PSV for steam generator

[dubulu123]

Reference is made to the attached file showing HP steam generation. HP BFW is admitted in the steam generator & HP steam @ 39 Kg/cm2 g gets generated, heat exchanging with process media on tube side of steam generator. HP steam thus generated is routed to convection section of a heater for generating superheated HP steam.
PSV-A is provided on the steam generator for blocked outlet case @ set pressure of 44.0 Kg/cm2 g. Which will protect the equipment. PSV-B is provided on outlet line of heater with same set pressure of 44.0 Kg/cm2 g also for blocked outlet case. This is for piping protection.
I believe the reason for providing two PSVs as equipment & piping are getting separated in two different systems because of a NRV on equipment outlet line.If not, What & which way PSV-B serves as a protection.Else, we can delete the requirement of PSV-B.

Sincerely requesting your kind attention.
Thanx all in advance

Dubulu

 

[pennpiper]

PennPiper (Piping Engineering and Design)
PSV - B cannot be eliminated.
It not only protects the down stream piping but it is protecting the tubes inside the convection section of the heater. The tubes here and the piping on both sides of the heater can be blocked in and the heater is still firing away.

Remember, the commodity in the fired heater tubes serve two purposes. First, to adsorb the correct level of heat for some later purpose. Second, it cools the tubes inside the heater and prevents catastrophic tube burn-out. If there is a stoppage of the flow or no flow at all and the burners are still going full blast then you can have a real bad day.

Just my opinion.

 

[dubulu123]

tubes in the heater are designed for no flow condition.considering this tube rupture due to blocked flow can be ruled out .

 

[ash9144]

Tube failure can never be "ruled out". At some point you will have tube failure.

 

[dubulu123]

but if the 1" valve across the NRV is kept open,then any pressure gets generated due to blocked heating will get released to the exchanger side safeguarding the tube.but now the question is whether or not this 1"is adequate?

 

[CJKruger]

dubulu123, the superheater PSV cannot be deleted as it is mandatory per ASME I (PG-68.1, and 67.1 in your case).

Cilliers

 

[MJCronin]

dubulu,

Why are you so determined to remove this valve ?