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# Hello I have to calculate area req

## Hello I have to calculate area req

(OP)
Hello
I have to calculate area required for an orifice . The downstream pressure is fixed. The flow is a multiphase flow of crude and steam.(Crude flowrate = 2000kg/hr and steam is 50kg/hr) If any standard sizing procedure is available, can anyone please share it ?
And can this be simulated in aspen hysys using a valve ?( if the orifice has multiple holes )

### RE: Hello I have to calculate area req

I think some theoretical approaches use an HEM model (see Leung procedure in API 520) to do this type of analysis. However (especially for multi-hole orifices) your flow regime is EXTREMELY important to flow calculations - is this annular, wave, slug, or other type of 2-phase flow?
A poster in the thread linked below asserts that instead of fl/D, you can use Kd in the Leung approach. I do not know if this is valid.

An estimate of Kd is provided here:
https://www.inglenookeng.com/orifice-flow-for-two-...

Take note of the conditions of the testing that found the Kd. I do not know if the liquids used - i.e. a volatile liquid with measurable quality versus your case of two different fluids - would affect their proposed equation for determination of Kd.

Two-phase flow is tricky stuff. Using the above, I would do your best, but would also want to run a pilot test if possible to verify results before installing in the full-scale equipment.

### RE: Hello I have to calculate area req

(OP)
Thank you for your prompt response

any idea if this can simulated in aspen hysys ?

### RE: Hello I have to calculate area req

What accuracy do you seek?

### RE: Hello I have to calculate area req

(OP)
Not very precise

Approximate value is okay(within 10-15%)

### RE: Hello I have to calculate area req

What is the pressure?

*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***

*** 'Pressure-relief Valve' is the equivalent ASME/API term ***

### RE: Hello I have to calculate area req

You are describing a restriction flow device. Your supplier will help, and proform a water flow test for the various parameters needed.

### RE: Hello I have to calculate area req

#### Quote (ReemaK)

Approximate value is okay(within 10-15%)
Do not believe them.

Give up this idea. Choked 2-phase flow has not been studied properly and has no a proven math model. Simultaneous phase changes and sonic velocities are almost unable to be predicted with accuracy you seek. Some models do exist but those were created based on similarity criteria of 1-phase flows so no one knows actual accuracy of those.

Note that you are trying to control a crude oil having unstable and unknown composition. Look carefully at fluid properties you implement and an impact of those to result.

500-1000% - may be, 10-15% - no way.

Also note that sonic flow requires extra hardness of bore and no one has experience in deterioration of that. Projections - may be, experience - no way.

Wide industrial implementation of some technique requires extensive science studies and piloting. A problem you are trying to solve is subject of some Nobel Prize in far future.

### RE: Hello I have to calculate area req

(OP)
Thank you all for your inputs.

I will go through the articles @pierreick

### RE: Hello I have to calculate area req

The model piperick referenced is not suitable as treats air-water mixture where no vaporizing occurs. Crude oil is a mix of hydrocarbons having light boiling components, solved above critical gases and even some solids (asphaltenes). Crude oil ≠ water and steam ≠ air.

### RE: Hello I have to calculate area req

(OP)
Thank you @shvet...yes these two combinations are enitrely different...even in my case when steam is added to the crude, some hydrocarbons vaporize...

### RE: Hello I have to calculate area req

Shvet,
what is your recommendation? I believe orifice is not suitable for this application.
Pierre

### RE: Hello I have to calculate area req

Avoid 2-phase controlling. There exist classic means for controlling in crude oil production&processing. There is no need of an invention regardless a problem nature behind of ReemaK's post.

### RE: Hello I have to calculate area req

(OP)
Application is crude and steam are passed through a nozzle...which has an orifice at the outlet of the nozzle...downstream pressure of nozzle is fixed..

### RE: Hello I have to calculate area req

#### Quote (ReemaK)

Application is crude and steam are passed through a nozzle...which has an orifice at the outlet of the nozzle...downstream pressure of nozzle is fixed..
It changes nothing. 2-phase is still not be able to be predicted properly.

### RE: Hello I have to calculate area req

Why an orifice and not a control or choke valve.

Pressures and pressure difference and temperatures are important here, but two phase flow through an orifice is complex and gets worse the larger the pressure difference is. You provide no information.

Is this critical flow or sub critical?

Crude oil and Steam mix??

Is this new or has something changed?

What was used before?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Hello I have to calculate area req

(OP)
It is an orifice plate and has multiple holes (as i mentioned in my first post).

I know the pressure that is to be maintained downstream of the orifice...I have to size the orifice and check how much is the back pressure in the nozzle and check upstream pressure required...the criteria is that the crude shouldn't vaporize at that upstream pressure at the inlet...

The pressure to be maintained downstream of the orifice is around 3 bar...and temperatures are in the range of 230C

This is not a project I am working on entirely(as I am new to the company)...only this nozzle part information has been given to me...I have no idea whether this a completely new design or the other department is just cross-checking the existing design...

Thanks once again to everyone for all your replies !!

### RE: Hello I have to calculate area req

Well nothing is making any sense to me. too many interconnecting parts to this which is impossible to understand, but a multi hole orifice now as well!

I would go back to whoever gave you this hospital pass and say not enough information and any calculations are subject to field trials.

Or install a control valve.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Hello I have to calculate area req

Looks like some one has goofed up on the design of the upstream single phase liquid nozzle, and now they want to patch up the deficiency by installing a 2 phase restriction orifice downstream.
Its not going to work.

### RE: Hello I have to calculate area req

hi,
Can you share a Pfd or Pid to vizualize your process? Do you need to stick to this technology of meter?
Pierre

### RE: Hello I have to calculate area req

(OP)
I will try to get it
But as of now I don't have any PFD & PID with me

Thank you !!

### RE: Hello I have to calculate area req

No PFD, no P&ID, and not material balance data with nominal fluid properties.

A poorly defined process, suggest the least of your worries are trying to size the piping components.

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