Recent content by Justice100

Thanks little inch. I am talking about where there is no vessel. For a let down station then I’ve seen it taken from the psv inlet tee normally as you say. My colleague thinks for scenarios with no vessel the dp should be from the pressure source. I can’t see that it explicitly states this in...

Hi all Just looking for some wisdom on where the 3 % psv inlet dp should be calculated from. As there are differing views internally. 1. Pressure let down - a pressure control valve lets down pressure, there is no associated vessel so the psv is located on the downstream piping. Should the...

By blowdown, I am referring to the standard term used for emergency depressuring of a vessel/system in the oil and gas industry for jet/pool fire protection. The setup is as per my sketch. The plant is currently under construction, I wasn't involved in the design but I have been asked to review...

Thanks Shvet. I have now run it in a dynamic simulator because it was bugging me so much. The upstream vessel completely empties its liquid via the blowdown valve leaving it as a vapour filled vessel at a pressure of about 40 barg. Then vapour starts to be released via the blowdown valve, with...

Thanks George. Out of interest I just ran a simulation for just the upstream vessel where the blowdown valve is on the vessel bottom. The vessel starts at 100 barg but liquid level is completely lost by the time the vessel is at ~20 barg. This can't be reflective of the what happens when the...

Hi all, I am looking at emergency blowdown of two liquid filled vessels that are linked via piping at the bottom. The blowdown valve is off the top of one vessel (I have attached a sketch). The liquid is hydrocarbon condensate at its bubble point. Assume for simplicity that both vessels are...

Thanks for responding. I have run it on Aspen Flare System Analyser with hot water at 145 DegC and a volume flow equivalent to the gas flow into the shell at shell design pressure. The case won't completely converge, the water flashes at the end of the header/entrance to the KO Drum but the...

I need to have a look into tail pipe slope. My initial thought was that it would as per an RV, located such that it slopes down into the flare header but from a transient perspective it needs to be as close to the shell as possible. I'll speak to the guy doing the transient and see if he can...

Hello all, I have a shell and tube HE with dense phase HC fluid on tube side at 350 barg and hot water on the shell side at 15 barg and 150 DegC with a design pressure of 24 barg. The shell will be protected by 2 bursting discs connected to the main flare header via tail pipes and a sub header...

Great work snickster! As you say the point for the "of air" is that the basis for the relief rate is based on air through a nozzle. This depends on composition for an ideal gas so I need to use equation D.35 to convert. I saw someone suggest Grahams law, which also makes sense to me now.

Thanks for responding. Why do they state "of air" for all the rates in API2000 if it is a perfect gas, reasonable assumption at tank conditions, then stating Nm3/h makes the MW irrelevant?

For API 2000 the relief rates are defined as Nm3/h of air. When looking at for example thermal inbreathing - My tank is blanketed with fuel gas with a PCV that will open up at 0.1 barg to let fuel gas in. Once I have the required flow rate in Nm3/h of air how to work out fuel gas consumption...

To Heaviside1925: People change minds! No, it is simply pressure control based on an upstream separator; the Separator is fed from multiple wells/choke valves. Precise control is not necessary. Control is required across the entire range. Again, precise control is not necessary, just need to...

Hi, We are in a position where we are about to install a pressure control valve but new requirements have come in for a much lower turndown so the intention is to install a small control valve in parallel to provide the turndown. There needs to be controllability all the way from the normal...

Thanks both. For clarity I am taking max pump pressure as suction vessel psv set point plus pump dead head. 1504 - I was really concerned with the implication that to avoid a high pressure trip you need to set the design pressure of the system at max presume/0.7. Little inch - 7.2.2.2. I’ve...