Depends on what flow rate the flare radiation was calculated / simulated on?

Not many details here....

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@LittleInch

we have a brownfield project,we have requested the contractor to update the flare radiation report, the flare capacity is not exceeded, I need to know even if the flare capacity still within capacity , if the flare radiation can be affected?

Can by affected, can be unaffected depending on calculations as radiation depends on many factors and capacity is only one of many. You are able to conduct a preliminary calculation by yourself, it is not overcomplicated.
https://sheet.zohopublic.eu/sheet/publishedrange/7...

No one here can say as we don't have access to any data or reports or anything really.

Flare "capacity" might be quite different to the actual capacity used to generate the flare radiation report.

Or maybe it's all ok?

Type of gas, mix of gases and flowrate can all change the radiation.

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

if the gas composition has been changed slightly (same HHV), flow capacity not exceeding design , ambient cd are the same, is it worth to update the Flare Radiation and Vapor Cloud Dispersion report?

IMHO, Yes it is as you're not answering the pertinent question which is:

Was the flowrate used in the radiation and vapour cloud disposal report equal to the design capacity or not.

We can't see the report and I'm struggling to believe updating the report is either a costly or time consuming thing to do and then no one can ever question the design.

If the radiation report was undertaken using a flow of say 50% of the "design" capacity then run it at twice the flow and buildings might burn down when the flare goes off or people injured.

Also analysis methods have changed over the years. How long ago was this previous report?

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

Was the flowrate used in the radiation and vapour cloud disposal report equal to the design capacity or not.
Yes equal

We can't see the report and I'm struggling to believe updating the report is either a costly or time consuming thing to do and then no one can ever question the design.
Cost

If the radiation report was undertaken using a flow of say 50% of the "design" capacity then run it at twice the flow and buildings might burn down when the flare goes off or people injured.

100% design capacity, the new equiment has been added, staggered blowdown has been set in order to not exceed the design capacity

Also analysis methods have changed over the years. How long ago was this previous report?
since 2017

OK.

Now that is clear then it would appear that you are not exceeding the design flowrate which has been used previously.

Quite recent so I would say you do not need to revise the radiation analysis.

The real issue is who is going to authorise this? You need to talk to them to get their buy in, but it would seem reasonable not to repeat it based on your answers above.

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

Permissible radiation flux ( which can be obtained from Operating Company standards or from the relevant API) will be different depending on the cause of the flaring event. So even if the design capacity is not exceeded, the permissible radiation flux rate at points of interest will depend on whether the cause of this new peak rate is the same as that for the design case. Also note the points of interest for the permissible flux rate may differ depending on the cause of flaring event.

Same goes for dispersion analysis.

The contractor has to provide suitable justification for not carrying out a radiation study, and it cannot be just a simple case of whether design case flare capacity is exceeded or not. Sometimes, operating philosophy may have also changed since 2017. Sometimes, new equipment may have been installed after 2017 which may see high radiation loads. Tread carefully.

Hi,
You may want to take a look at this document to support your study.
Pierre

• https://files.engineering.com/getfile.aspx?folder=2bf1b40b-3651-4c3f-845c-e