3 replies to this topic

[go-fish]

I am doing adequacy check calculation on a PSV on a de-ethaniser overhead receiver for an existing facility(see sketch attached). The overhead from the de-ethaniser goes to a condenser and then to a receiver vessel. The vapor outlet from the receiver goes to the fuel gas header and the liquid is full reflux to the de-ethaniser. The column overhead has a PSV set at same pressure as the PSV on the receiver. Based on my understanding, I am considering the following as credible relief scenarios: 

1. External Fire
2. Blocked vapour outlet
3. Loss of reflux due to blocked liquid outlet as column PSV already accounts for reflux failure. 

I have calculated relief load for the fire case. I am not really sure for the relief load calculations for blocked vapour outlet. Should I take relief load as the normal flow through the control valve at relieving conditions and use vapour sizing equation to come up with the orifice size?

Attached Files

•  sketch.pdf   4.71KB   40 downloads

Edited by go-fish, 03 January 2018 - 09:52 AM.

[Padmakar Katre]

I am doing adequacy check calculation on a PSV on a de-ethaniser overhead receiver for an existing facility(see sketch attached). The overhead from the de-ethaniser goes to a condenser and then to a receiver vessel. The vapor outlet from the receiver goes to the fuel gas header and the liquid is full reflux to the de-ethaniser. The column overhead has a PSV set at same pressure as the PSV on the receiver. Based on my understanding, I am considering the following as credible relief scenarios: 

1. External Fire
2. Blocked vapour outlet
3. Loss of reflux due to blocked liquid outlet as column PSV already accounts for reflux failure. 

I have calculated relief load for the fire case. I am not really sure for the relief load calculations for blocked vapour outlet. Should I take relief load as the normal flow through the control valve at relieving conditions and use vapour sizing equation to come up with the orifice size?

 

I think, yes you should size PSV for the normal vapor flow thru the control valve.
 

[go-fish]

 

I am doing adequacy check calculation on a PSV on a de-ethaniser overhead receiver for an existing facility(see sketch attached). The overhead from the de-ethaniser goes to a condenser and then to a receiver vessel. The vapor outlet from the receiver goes to the fuel gas header and the liquid is full reflux to the de-ethaniser. The column overhead has a PSV set at same pressure as the PSV on the receiver. Based on my understanding, I am considering the following as credible relief scenarios: 

1. External Fire
2. Blocked vapour outlet
3. Loss of reflux due to blocked liquid outlet as column PSV already accounts for reflux failure. 

I have calculated relief load for the fire case. I am not really sure for the relief load calculations for blocked vapour outlet. Should I take relief load as the normal flow through the control valve at relieving conditions and use vapour sizing equation to come up with the orifice size?

 

I think, yes you should size PSV for the normal vapor flow thru the control valve.
 

 

 

Thank you for your response. How do I calculate the relieving temperature corresponding to the relieving pressure for the blocked vapour outlet case? I have the simulation.

[Padmakar Katre]

 

 

I am doing adequacy check calculation on a PSV on a de-ethaniser overhead receiver for an existing facility(see sketch attached). The overhead from the de-ethaniser goes to a condenser and then to a receiver vessel. The vapor outlet from the receiver goes to the fuel gas header and the liquid is full reflux to the de-ethaniser. The column overhead has a PSV set at same pressure as the PSV on the receiver. Based on my understanding, I am considering the following as credible relief scenarios: 

1. External Fire
2. Blocked vapour outlet
3. Loss of reflux due to blocked liquid outlet as column PSV already accounts for reflux failure. 

I have calculated relief load for the fire case. I am not really sure for the relief load calculations for blocked vapour outlet. Should I take relief load as the normal flow through the control valve at relieving conditions and use vapour sizing equation to come up with the orifice size?

 

I think, yes you should size PSV for the normal vapor flow thru the control valve.
 

 

 

Thank you for your response. How do I calculate the relieving temperature corresponding to the relieving pressure for the blocked vapour outlet case? I have the simulation.

 

 

Estimate dew point temperature corresponding to the relieving pressure. In simulation, specify composition of ovhd vapor stream, relieving pressure and vapor fraction =1, the simulator should flash this stream and will give the dew point temperature.