Possible fouling.
UV Irradiation Technoloav WorksrouD Participants:
Jerry Hall, Moderator Dan Nolan, Expert Jerry Ham
James Buzan Greg Hardy Joe Smith
Answers t o Technoloav Checklist Questions.
1. How well do technologies treat (reduce the concentrations of) spec fic chemica groups (e.g., volatiles, metals, H,S, ammonia and organics)? (Note: salinity is incorporated as a matrix effect).
UV increases rate of oxidation by a factor of lo6 over simple chemical oxidation.
Destroys dissolved organics, volatile and non-volatile organic com pound s , i nc I u d i ng BTEX .
(Note: stripping will be cheaper for volatiles unless off gas treatment is necessary).
Napthenic acids will be destroyed at a lower rate than BTX.
H,S will also be oxidized, but UV/ozone.is not the method of choice.
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Copyright American Petroleum Institute Provided by IHS under license with API
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A P I DRx351 96 m 0732290 0553719 289 W
Will not destroy ammonia or dispersed oil droplets. Dispersed oil will just pass through - no interferences and no effect of process
anticipated.
Will not destroy metals or salinity. Salinity as carbonates will slow down reaction by scavenging hydroxyl radicals.
Contaminants such as biocides and other treatment chemicals used on platforms will also be destroyed if they are organic based. Rate of destruction will vary by compound.
May be able to allow only partial removals and still achieve compliance with toxicity limit.
2. Is additional chemical usage necessary to reduce toxicity?
There are a number of UV processes that can be used for produced water treatment
UV usually done with hydrogen peroxide, but need to minimize chemical usage on platform. Therefore, recommend UV together with ozone.
Easier to supply additional power for ozonator than deal with chemical storage, handling and safety issues.
3. What range of oil and grease and salinity can the technology tolerate?
Salinity:
Jerry Hall - Studies performed by Texaco show that salinity in excess of natural sea water salinity did not inhibit UV treatment. Reduced TOC to few ppm even at natural sea water salinity - but did not necessarily remove toxicity (no data).
Salinity can cause corrosion, may need to upgrade piping from stainless to high molybdenum alloy or possibly FRP (fiberglass reinforced plastic).
High carbonate concentrations will slow down reaction.
Oil:
Oil will just pass through the system. However, there is some concern about fouling the lamps.
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Copyright American Petroleum Institute Provided by IHS under license with API
Not for Resale No reproduction or networking permitted without license from IHS
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Other:
Jerry Hall - Experience with UV operation is that wipers must be used in the presence of high iron concentrations. Otherwise fouling will occur.
4. What are the equipment specifications?
Open tower with UV lamps distributed a t various heights.
Weight limit on platform is 200 Ib/sf. May require some configuration other than vertical tower.
Shape of equipment is irrelevant.
Electrical motors must be Class 1 Division 1 (explosion-proof).
Vessels above 1 2 to 13 psi must be pressure coded. May significantly increase costs; need to check in engineering study.
Additional power requirements - For 10,000 bbl/d UV/ozone unit, need 270 kW ( 1 79 kW for UV and 90 kW for ozone). UV/peroxide unit also 270 kW (for UV power).
5. What is technology's current operational state (¡.e., pilot, laboratory-scale or full-scale)?
Pilot Studies:
Performed tests on Gulf of Mexico samples in March 1992.
Developed preliminary estimates for North Sea systems.
Greg Hardy: Solarchem to perform Rayox pilot testing with PERF in late November on a Shell platform.
Purpose is to evaluate operation and performance of the unit.
Produced water flow is 14,000 bbl/d. Have soluble oil problem; oil and grease = 20 ppm on up. Also toxicity failures.
Small Rayox tower - 1 f t diameter by 6 f t height, 3 1kW lamps at various heights in the column. Will only treat about 5 gpm
continuously, but will provide kinetic data to evaluate design and operating requirements for full-scale.
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Copyright American Petroleum Institute Provided by IHS under license with API
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A P I D R m 3 5 1 ợ b 0732290 0553723 937 W
M a y also need t o first perform batch testing t o provide kinetic data.
Will look into performing toxicity tests on Rayox effluent.
Will look into treating acid-flow back wastes from well, because it elevates oil and depresses pH (worse case condition).
Commercial Applications:
Solarchem has sold 70 units - 50 t o 60 in use. About 200 installations in U.S. used t o treat similar types of compounds.
No definitive work on produced water.
Will the wiper be able t o keep the quartz sleeve clean enough for light t o penetrate the water. Need field experience, pilot studies planned.
Operations and Maintenance:
Designed t o operate with little attention. Have been operating remotely by modem.
Operates by programmable logic controller (PLC).
Experience with some UV/peroxide systems is that p H monitoring is required t o guard against fouling.
Lamps last a minimum of 3,000 hours (4 months). Lamps can be
changed quickly (1 per hour). Rayox will accept old lamps because they contain a small amount of mercury.
Air compressor used for wiper needs t o be maintained.
Possibility of pinhole leaks in glass and gas coming out will ignite.
M o s t systems are operated continuously. Batch is used for
unpredictable conditions such as variable waste stream characteristics.
produced water treatment should be continuous t o minimize operator attention.
6. What is the potential for technology improvements (Le., many versus few, rapid versus slow).
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Copyright American Petroleum Institute Provided by IHS under license with API
Not for Resale No reproduction or networking permitted without license from IHS
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A P I D R x 3 5 1 96 = 0732290 0553722 873 m
For large scale system, more economical t o produce ozone from oxygen than from air. Put pressure adsorption unit t o increase oxygen
concentration t o 75 t o 90% and then pass the enriched air through ozone generator. Oxygen can be a safety issue.
Wiper may or may not work for produced water Need further work t o develop appropriate wiper materials - For high salinity waters need t o use something other than stainless steel for brush material.
Need t o k n o w what the toxicants are in order t o better address improvements.
M a y not be necessary t o treat all of waste stream t o meet toxicity limit.
Are there any toxicity reduction performance data?
No, n o t for produced water.
Western Ontario study - evaluating toxicity reduction (microbial test) in specific chemical testing o f pentachlorophenol destruction.
Some groundwater applications for treatment of solvents require toxicity tests before surface water discharge (freshwater). Rayox effluents are passing the tests.
Jerry Hall: Has in-house data on complex wastewaters and specific chemical tests (napthenic acids).