3 replies to this topic

[arvind]

Hi dear,

This is regarding the relieving rate calculation for tube rupture scinario.
Process description: In kattle type reboiling condenser hydrogen along with C1-C6 (80% h2 and 20% hydrocarbon vol basis) flowing throgh the tube side and refrigarant throgh the shell side.
PSV is located at the shell side.

Design data:
Shell side design pressure: 13 barg ( refrigarant side)
tube side design pressure : 30 barg ( H2 and c1 to c6)

PSV set pressure is 12.5 barg.

How to calculate the relieving flow rate throgh the tube in case of tube rupture.

( Note: Tube side fluid is two phase where as tube bundle is submurge in the refrigarant in the shell side)

Thanks in advance

Arvind

[Satyajit]

Arvind,
Follow API 521. Take 1 tube rupture( broken into two piece) as a basis for calculating flow for PSV sizing.
Best regards,
Satyajit

[cmp74]

Arvind,

Normally , a complete tube rupture is assumed occurring at the tubesheet, such that on one side you have tubeside fluid flowing through the tubesheet (assumed an orifice) and on the other side , tubeside fluid flowing through the remaining part of the tube.

You have to calculate the flow thro the tubesheet side (orifice) and flow thro the tubesheet + tube side.You have to also consider whether flow thro the tube is choked or not.Being a 2 phase flow,"omega" method has to be used to calculate flows from both sides.

Once you have calculated flow from both sides , you add them and it becomes your relief load.You will have to know physical properties at the Relief pressure.

Once you have the relief load, the PSV needs to be sized.Again, use "omega" method (Appendix D, API 520)to calculate required relief area.

I have a technical paper in my office for this calculation. I will be able to upload it tomorrow.

[cmp74]

Arvind,

attached is the paper I used to calculate tube rupture relief load.

Attached Files

•  Tube-rupture-relief -sizing-method.pdf   788.35KB   1071 downloads