9 replies to this topic

[Ahmadhamzahperta]

Good day everyone, i have a question concerning flow in flare header and i have attached an image of the header. My question is, how could the flow converge into one stream and proceed to flare stack while having different pressure sources. wouldn't the highest pressure (Flow from PSV 2) force a reverse flow to the other line? or will there be control valves to regulate the pressure so it will equalized?

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[Pilesar]

At the junction of converging flows, there will be only one pressure. Flow will be in the direction of higher pressure to lower pressure. Determine the pressure at the junction and compare it to the source pressures to know the direction of flow.

[breizh]

Hi,

Do you think that the PSV will pop up at the same time? 

Agree with reply above.

Note Probably good to review the details of a PSV.

Pressure Relief Valve

Breizh 

[latexman]

Once the flow gets through the PSV nozzle (sometimes called an orifice), the pressure at the PSV exit is determined by the flow(s) and the  hydraulics of the flare header network and the flare.  The pressure just outside the flare tip is atmospheric pressure, right?  It is common practice to solve the flare header network given the flow(s) from the flare tip backwards toward the PSV exit flange(s).

[Ahmadhamzahperta]

Hi,
Do you think that the PSV will pop up at the same time?
Agree with reply above.
Note Probably good to review the details of a PSV.
Pressure Relief Valve
Breizh

To be honest i don’t know but i feel that for the PSV to be able be credited as an IPL it has to be independent. Therefore i think its more appropriate to consider the scenario in which three of them pop out at the same time

[Ahmadhamzahperta]

Once the flow gets through the PSV nozzle (sometimes called an orifice), the pressure at the PSV exit is determined by the flow(s) and the hydraulics of the flare header network and the flare. The pressure just outside the flare tip is atmospheric pressure, right? It is common practice to solve the flare header network given the flow(s) from the flare tip backwards toward the PSV exit flange(s).

So basically we calculate the pressure drop needed so at the junction all lines have the same pressure?

[Ahmadhamzahperta]

At the junction of converging flows, there will be only one pressure. Flow will be in the direction of higher pressure to lower pressure. Determine the pressure at the junction and compare it to the source pressures to know the direction of flow.

Alright, thanks my friend

[latexman]

Once the flow gets through the PSV nozzle (sometimes called an orifice), the pressure at the PSV exit is determined by the flow(s) and the hydraulics of the flare header network and the flare. The pressure just outside the flare tip is atmospheric pressure, right? It is common practice to solve the flare header network given the flow(s) from the flare tip backwards toward the PSV exit flange(s).

So basically we calculate the pressure drop needed so at the junction all lines have the same pressure?

Yes, at the one point all three PSV exhausts have in common, but that is not what I said.

[Ahmadhamzahperta]

Once the flow gets through the PSV nozzle (sometimes called an orifice), the pressure at the PSV exit is determined by the flow(s) and the hydraulics of the flare header network and the flare. The pressure just outside the flare tip is atmospheric pressure, right? It is common practice to solve the flare header network given the flow(s) from the flare tip backwards toward the PSV exit flange(s).

So basically we calculate the pressure drop needed so at the junction all lines have the same pressure?

Yes, at the one point all three PSV exhausts have in common, but that is not what I said.

My bad i thought when you said solving it backwards you mean calculating the pressure drop from the tip. Nonetheless i kinda understand it now, thank you

[latexman]

 

 

 

Once the flow gets through the PSV nozzle (sometimes called an orifice), the pressure at the PSV exit is determined by the flow(s) and the hydraulics of the flare header network and the flare. The pressure just outside the flare tip is atmospheric pressure, right? It is common practice to solve the flare header network given the flow(s) from the flare tip backwards toward the PSV exit flange(s).

So basically we calculate the pressure drop needed so at the junction all lines have the same pressure?

Yes, at the one point all three PSV exhausts have in common, but that is not what I said.

My bad i thought when you said solving it backwards you mean calculating the pressure drop from the tip. Nonetheless i kinda understand it now, thank you

 

Good.  Ambient pressure just outside the flare tip is known.  The pressure drop calculations backwards toward all 3 PSV outlet flanges is iterative, so they are unknown and will change until successive trials converge.  The pressure drop calculations starting with the 1 known pressure and working backwards towards 3 unknown pressures is inherently more stable than starting with 3 unknown pressures (initially they are guesses) and working forwards toward the 1 known pressure.  It seems intuitive to me, and that's the advice I've always heard and read about solving this type vent header set-up.