4 replies to this topic

[emliy]

Dear. All

 

I have a question about PSV relieving temperature.

I have a Heat exchanger. (not reboiler)

the shell side condition is 

- design pressure : 20 barg

- operating temperature : 90-80C

- design temperature : 200C

the tube side condition is

- design pressure : 40barg

- operating temperature : 0C - 10C

- design temperature : 70C

 

In case of calculating tube rupture case,  How should I select relieving temperature?

There's no comment in API 521.

In my opinion, relieving temperature seems to be design temperature (70C).

When tube rupture is occur, tube side fluid flow into shell side, tube fluid temperature will be risen by shell side fluid.

Is it right?

If not, please lesson to me.

Edited by emliy, 30 December 2015 - 07:25 PM.

[latexman]

At 22 barg (20 + 10%), will the shell side fluid (SSF) continue to flow, or will it be pushed back/stopped?  If pushed back/stopped, you have 100% tube side fluid flowing (TSF) to SS PSV.  So, TSF possibly @ 40 barg + 10% (what is the operating pressure?) through tube rupture and relieving at 22 barg sizing pressure.  Use the TSF coincident temperature at 22 barg, not the design temperature.

 

If TSF continues to flow at 22 barg, then you have a mixture of TSF and SSF going to SS PSV.  A more complex problem.  TSF possibly @ 40 barg + 10% through tube rupture, mixing with SSF, and to SS PSV at 22 barg.  Use operating temperatures, and thermodynamic mixing rules to determine what you have .

 

Maybe, you have a simulator?

[Bobby Strain]

You should never base engineering on your opinion, or that of others. You should use facts and standards and duly recognized practice as the basis for your design.

 

Bobby

[Ankit_Kumar]

Hi there,

 

I need to design PRV/RD on tube rupture basis for an exchanger’s tube side. Shell side is containing amines so it can’t be vented in the air. Hence, discharge of relieving device will be in the flare. Now I don’t know whether it will be rupture disc or pressure relief valve.

 

How to select it? I have tried API-520 & API-521 but couldn’t find the basis. Below is the specification of exchanger:

 

 

 

                       Tube Side                                                Shell Side

Fluid                                                      Methanol Columns                                   Cooling Water

Operating Pressure Kg/cm2.g                    7                                                               13

Design Pressure Kg/cm2.g                        10                                                               19

 

Appreciate if you can guide me.

Edited by Ankit_Kumar, 05 January 2016 - 09:06 AM.

[Ankit_Kumar]

no reply