Boiler Question

[Viper5]

I'm trying to understand how a boiler component can add heat and still be considered an isobaric process.  I know that it should according to the rankine cycle.  It seems like if you add heat inside a rigid-walled structure, the pressure must be increased if a superheated state is reached per the ideal gas law.  Especially if subcooled fluid is used at the inlet.  Please help me understand this.  Thanks.

 

[JHW 3d]

Is the volume constrained in your boiling process?

 

[P-E]

Adding heat and raising temperature are not the same thing.  This is true inside the steam drum.  The boiler feed pump and feed water control valves set the pressure going into the drum.  Pressure is kept constant in the superheater via controls. 

 

[Audi Driver P.E.]

That is exactly how boilers work.  If you don't relieve the pressure, pretty soon you have a nice bomb.

 

[Viper5]

Thanks.