You have to evaluate the volume of vapors and justify the cost of piping the vapors to the flare.

The API separator should be covered in any case. You should not be getting a large volume of vapors off the API separator if it is covered. Note that the API separator is frequently considered to be a fire hazard as well (another reason for covering it).

The extent of the air pollution control procedures is often dicatated by the local air pollution regulations.

I agree with the response you got from bimr that your API separator should be covered. If your refinery is in the United States, your local air quality regulatory agency is either asleep or very incompetent. An open separator is not only a fire hazard, the vapors are a health hazard for the operators.

Milton Beychok
(Visit me at www.air-dispersion.com)
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Bimr, Milton,

Thanx for answers. However, I am still in the dark regarding second part of my original message. Please try to help again.

The two units, tanks and API separators, are very low pressure sources and connecting to the plant flare would not be a good idea without a lot of extra equipment. The primary concern is back flow from the flare header.  Next possible air contamination from the tanks and API seperators.  Lastly, controls to make everything work properly.

I'd investigate a few solutions. The first being dedicated thermal oxidizers, second vapour recovery systems, or a combination of those.

dcasto,

Thank you very much for your answer. Can you, however, be more specific about dedicated thermal oxidizers, especially if you have first-hand experience or know alot about them. If you are familiar with working example(s) of this solution in practice, better still!

Here is a typical system: http://www.nao.com/fume.htm

Its a small flare that has supplimental fuel to assure complete oxidation of the VOC's

Regarding the second part of your query, you have to evaluate the volume of vapors and justify the cost of piping the vapors to the flare.

Covering the separator will drastically reduce the volume of vapors coming off. The cover may even eliminate the need to collect the vapors.

Then, you will have to evaluate the cost of a piping and a fan to force the vapors to the flare.

It is very doubtful that you enough vapors to justify installing an air pollution control device like dcasto recommends.

In my state some sweet gas wells install a perminate oxidizer, like one of these, on every wellhead for the 7 to 10 days per year the pipline may shutdown or they need to work over the well. If the penalty for pollution or pressure from the residents is large enough, you'll find the money.