4 replies to this topic

[shahidulislam48]

Hi,

 

Is there any equation for calculating relieving temperature for wetted vessel like unwetted vessel for Fire Case?

Also in the case of other relieving scenarios? Any code or regulations?

 

Many Thanks.

Shahidul

[fallah]

 

Is there any equation for calculating relieving temperature for wetted vessel like unwetted vessel for Fire Case?

Also in the case of other relieving scenarios? Any code or regulations?

 

 

Shahiidul,

 

If the liquid inside the vessel is a pure component, the relieving temperature would be liquid boiling point corresponding to the relieving pressure...

 

If the liquid is a multicomponent, the relieving temperature wouldn't be fixed and be progressively increased as the boiling point of the liquid is going to be increased due to light components reduction...

 

[shahidulislam48]

 

 

Is there any equation for calculating relieving temperature for wetted vessel like unwetted vessel for Fire Case?

Also in the case of other relieving scenarios? Any code or regulations?

 

 

Shahiidul,

 

If the liquid inside the vessel is a pure component, the relieving temperature would be liquid boiling point corresponding to the relieving pressure...

 

If the liquid is a multicomponent, the relieving temperature wouldn't be fixed and be progressively increased as the boiling point of the liquid is going to be increased due to light components reduction...

 

Hi Fallah,

 

Thanks for your reply.

 

Since we have to mention both relieving pressure and temperature as pre-requirement for sizing PSV, for multi-component system wouldn't relieving temperature have any significance or we have to mention the temperature that corresponds to highest boiling point temperature?

 

Best Regards,

Shahidul 

[fallah]

 

Since we have to mention both relieving pressure and temperature as pre-requirement for sizing PSV, for multi-component system wouldn't relieving temperature have any significance or we have to mention the temperature that corresponds to highest boiling point temperature?

 

 

Shahidul,

 

For two phase and multicomponent systems in fire case the relieving temperature varies from IBP to FBP and continues up to a temperature where vessel would failed.

 

In fact, because in most fire cases it's logically assumed the PSV cannot protect the vessel from failure, relieving temperature wouldn't be so significant in relevant PSV sizing and can be taken a value between IBP and FBP; but if you are insisting to calculate reaching an exact value you can use both IBP and FBP and select the one leading to higher relieving area as relieving temperature.
 

[shahidulislam48]

Thanks Fallah for your input.