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Modernization, expansion or product quality improvement projects in refinery or petrochemical Industry may require additional secondary processing plants and facilities. In such cases, the existing size of main Flare header and also main Flare stack along with the stack height may be limiting requiring revamp of both of them. Based on acceptable radiation levels from the Flare stack, it is required to have a minimum separating distance from Refinery Flare to other facilities (like process units or tankage etc) at refinery & petrochemicals. Is it, from safety point of view, possible to locate the new Flare stack closer to the old flare stack? If so, what should be minimum separation distance between the two stacks? What are the criteria for such case?
 
Answers
07/10/2008 A: Samuel Sinanan, IPSL, Samuel.Sinanan@ipsl.co.tt
You should consider the radiation if you plan to do maintenance work on one flare while the other is in operation. A radiation level of 1100 Btu/hr/ft2 from tip to tip should be considered. This should give a minimum distance between the flares.
15/09/2008 A: KengYong Chan, Air Products & Chemicals, Inc, chanky@apci.com
The CCPS book does not mention any spacing criteria between flares. But, there may be a need to consider noise and luminosity effects of having two flares in close proximity to each other and any local regulatory requirements for noise, luminosity, in addition to thermal radiation.
08/09/2008 A: Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
If stack height and other issues "could create a future problem" I strongly recommend you ensure performance of the flare line is kept optimum by installing equidistant 25mm valved stub flanges at 12 o'clock every 100 metres. This way, once up and running and should the plant experience back pressure or anything else as a result of an internal Flare line fouling issue e.g. Sulphurcrete, Pyrophoric sludge build up, the entire length of Flare Line can be cleaned mechanically "On-Line" with the waste being removed to the knock out drum without the need to shut down at all.