Design Temperature when Full Vacuum Conditions? 1

[erkuts]

Hello,

I would like to ask a question. When i looking design values of our pressure vessel, design pressure 27,07/F.V and design temperature 860/121 Celcius.
What dooes 121 Celcius or 250F value mean? Is it permissible outside temperature or another issue ?

Thanks,

 

[SnTMan]

I would normally interpret that the 121 C is associated with the FV condition. You should confirm this is true.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JStephen]

I would take that to mean that the vessel was good for any pressure between 27.07 & full vacuum, and for any temperature between 860 and 121.
I would assume the temperatures are the vessel metal temperatures, not the outside temperatures. Although it would be odd for the lower temperature to be above ambient.

 

[TGS4]

The coincident pressures/temperatures are: 27 (whatever unit) and 860 (whatever unit) and full vacuum and 121°C. You need to design for both conditions.

 

[SnTMan]

Just want to clarify: FV at 121 C and at 860 C are very different conditions.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[erkuts]

Design values as below.

What can i say about this pressure vessel ? is 121 C a limit?

 

[TGS4]

121C is coincident with the full vacuum condition. That is consistent with a steam out case. Normally the outlet to this furnace (hence the term pigtails) is 860C coincident with 27.07 kg/cm^2 internal pressure.

Pressure vessels and piping are both designed for coincident conditions of temperature and pressure. Your high temperature will not occur during vacuum.

 

[erkuts]

can we say that steam out should be maximum steam temperature 121 C or after steam out 121 C should not be exceeded?
In which step 121 C is a limit ?

 

[TGS4]

Steam out is what's going to cause the vacuum - after the steam condenses (and if you haven't prevented it by leaving one end open), it will draw a vacuum.

For the purposes of the design, you need a coincident temperature for the vacuum condition. 121°C is a good number for that.

I'm not certain what you mean by "step"?

 

[erkuts]

I mean when internal pressure 27 kg/cm2 and max temp 860 C. No problem.

But when full vacuum condition occurs, we should not exceed 121 C.

i understand full vacuum condition definition as if steam condensates internal pressure will be 0 and we have existing external pressure 15 psi.

 

[TGS4]

You are correct.

 

[erkuts]

Thank you