Make-up Water Requirements for Oil Refinery 1

[kgwags]

I am doing some prelim project research as to the make-up water requirements and general information on water balances for a large, full-conversion refinery. I've done some preliminary research that has provided some good "rules of thumb" such as:

o "Best Practice" Refineries might use less than 20 gal of water per barrel of oil
o General industry averages might be as high as 60-90 gal of water per barrel
o CW make-up accounts for about 50% of total refinery water needs considering (BFW blowdown, process water, unrecovered condensate, etc).

I am interested in determining "how low can you go" with regards to total water consumption in a refinery and whether the technologies that support water reuse (e.g. wastewater reused as CT make-up) have been successfully proven on a commercial scale. I am also looking into air/fin-fan coolers/condensers in lieu of CW exchangers and what impact this can have on reducing water usage, but also on increasing capital costs.

I just stumbled onto this site and noted the substantive feedback here. Thanks for any input and sorry for the long message.

 

[rmw]

What are your ambient conditions with respect to CT losses due to evaporation?

rmw

PS: welcome to the site. Long posts that help make your inquiry understandable to us are not a problem.

 

[kgwags]

Well, the ambient conditions for this particular site are wide-ranging....very cold in winter and summertime peaks of 90F or higher.

However, I am trying to get a broad and comprehensive understanding of the potential range in water usage and water minimization practices, and the key variables I can manipulate, before taking it to the site-specific level. For example, I know I can replace some CW exchangers with air-cooled exchangers. But in the case where I'm condensing light hydrocarbons, this can increase the operating pressure and increase other capital costs (not just for the heat exchanger), and generally move away from a more optimal operating point.

So to sum up, for a site that has rather severe water restrictions, I'm trying to understand the applicability of water reuse and CW replacement with air exchangers to see how low I can drive make-up water requirements.

Thanks.

 

[mbeychok]

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kgwags:

I made a study for a client about 25 years ago, part of which was to study the water losses from four refineries ranging in size from 30,000 to 130,000 barrels of crude oil processed per stream day.

The average water losses for those refineries were:

Cooling tower evaporation loss = 15 (gal of water)/(bbl of crude)

Wastewater discharge = 10 to 40 (gal of water)/(bbl of crude)

Other losses = about 3 percent of total water losses

Total water use = (25 to 55)/0.97 = 26 to 57 (gal of water)/(bbl of crude)

The water intake of the refineries also includes the crude oil BS&W. The average BS&W only amounted to less than 1 percent of the total water intakes... and that is not included in the above data.

Milton Beychok
(Contact me at www.air-dispersion.com)
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