Designing a Natural Gas Pipeline

hi, would you explain me your question in some detail?????

as you mention design pressure is 100 bar so your class/rating would be #900 (assuming design temp is at/above 60 degree), regarding flare design all required information should be mention in P&ID and datasheet or in contract documents of the same.........................

regards

Kapse

Hi,

This flare will be installed near the emergency shut down valve,the capacity of relieving gas is 2000000kg that we want relieve it about 8 hours,pressure is 92 bar and temperature is 55 c,Please tell me the inlet gas pressure (flare),and which equipment can depressurize?

Thank you

I understood your query as follow :

You would like to depressure a pipeline during emergency shutdown and the destination of pipeline content is flare system.

For emergency depressuring (cold depressuring only) of a system, there is a time factor involve.How long your would like to depressure your pipeline ?

Pipeline depressuring would lead to low temperature. The degree of low temperature subject to inventory, the depressuring rate, pipeline latent heat, composition of fluid, etc. For a pipeline, inventory is huge. Quick depressuring i.e. 15 minutes would lead to very low temperature and pipeline may experience low temperature embrittlement. Depressure rate is high...Thus in many event depressuring a pipeline is a critical issue and need careful analysis. In many event, it does not follow the normal recommended time per API Std 521 i.e. 15 minutes...For your case 100 bar...you will probably see this problem...

What is suitable pressure in flare header ?

I don't see a serious relationship between flare header pressure and pipeline depressuring. The flow would be critical for 90% of the time. Moreover flare header pressure is low in many event...

which equipment i depressure the fluid ?

Isn't your case is pipeline depressuring ?

From the questions that you raised, your seem a bit fresh in this area. This area involve safety and shall be handled in serious manner. Wish you have experience engineer backing you...

Sorry to come off topic, but could you advise me please

upon who to contact for an invention based on the flare?

Many thanks.

jt.

Now I have regained consciousness, the world looks a different place.

I am sorry. I don't really understand your meaning...

Are you looking for flare tip vendor or authority on flare tip ?

Hi,

Thank you for attention,

I need design flare after depressurizing but I don't know the pressure in inlet flare,I found the back pressure is near the 1.5 bar ,and I think it is very low,

So I must depressurize from 92 bar to 1.5 bar!!!(non-controlled depressurising)

and if it is correct ,how to apply valve equation in HYSYS Depressuring?(relief ,general,...)

Regards,

"Pressure in the flare", to be exact back pressure to pressure relief and/or depressuring valve will be the built up (flow due to itself) plus superimposed (flow due to others) from the flare tip for conventional with no pressure recovery system. Read API STD 521 for detailed definition of Back pressure, Built-up back pressure and Superimposed back pressure. Back pressure i.e. 1.5 bar although is low but it is pretty normal pressure.

Depressurize from 92 bar to 1.5 bar, pretty obvious is critical or choked flow where back pressure is lower than critical pressure. Back pressure i.e. 1.5 bar or 3 bar or 5 bar has little / no impact to the flow. Read more in "A refresh to Process Engineer on few phenomenons in restriction orifice".

Since you mentioned non-controlled depressuring, i guess you are referring BDV+RO configuration (discussed in "Controlled and Non-controlled Type Depressuring"). Well...the example is BDV/RO fix bore. You may consider variable by installing a control valve i.e choke for better blowdown management.

If you using HYSYS to study the depressuring, first fast important thing is make your depressuring is "bug-free". There are quite few issue with the depressuring unit which required additional attention or workaround to get rid the error first. R-in-R-out...

Now concerning the valve equation, you may consider to use the [General] equation. Some explanation in "How to apply valve equation in HYSYS Depressuring ?". [Fisher] equation may be considered but ensure you are bug-free as explained in "Bug in ASPENTECH HYSYS 2006 Dynamic Depressuring Fisher Valve model".

Good luck.