Assuming a 10,000 bbl/d UV/ozone system and 90% destruction of BTX, the capital and operating costs are summarized as follows:
Capital Costs:
$500,000 for Rayox UV/ozone system
$350,000 for Rayox UV/peroxide system.
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A P I DR*35L 9 6 m 0732290 0553729 blib m
Operating costs:
$0.024 per bbl - includes electric power for lamps and ozone generator, and replacement of lamps a t 3,000 hours.
Additional generator capital cost would be about $0.04 to 0.05 per kWh.
If additional generator cost is included in operating costs, total operating costs are estimated to be $0.05 per bbl. Power not a fatal flaw.
12. List any recommendations for research needed to make the technology more practical for offshore use.
Need to evaluate lamp fouling. Wiper operated by PLC may need to be adjusted to brush more frequently.
Testing for toxicity reduction.
Evaluation of cost to address Class I requirements (explosion-proof), pressure vessel requirements and corrosion potential.
StriDDina/Extract¡on WorkarouD ParticiDants:
Tracy Fowler, Moderator David Hand, Expert Don Mount
Michael MacNaughton Bac kqround.
The question of whether or not to address extraction treatment in addition to stripping was discussed.
Solubility is important for extraction.
Extract with solvent.
Put extracted material in oil stream?
Workgroup decided to primarily address stripping. Extraction is discussed in Question #10 of the Technology Checklist.
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A P I DRx352 96 0732290 0553725 582
Answers t o Technoloqv Checklist Questions.
1. How well do technologies treat (reduce the concentrations of) specific chemical groups (e.g., volatiles, metals, H,S, ammonia and organics)? (Note: salinity is incorporated as a matrix effect).
a
a
a
o
a
o
a
a
O
a
a
For volatile compounds with Henry's Constant > 0.005; expect 95%
removal and greater.
A t room temperature, H,S and ammonia can be stripped, but pH must be adjusted. For H,S, pH should be lower (pH 4 t o 6). For ammonia, pH should be higher (pH IO).
No distinction necessary between acidic, bosk, and neutral organics.
Ferrous iron may be oxidized by air stripping and could foul equipment.
Solubility of oxygen is reduced at higher temperature, so oxidizable materials may not be easily oxidized.
Volatile emissions should not be an OSHA problem, at the air t o water ratios of interest. Also volatile concentrations are relatively low.
Mount noted that not many of the produced waters tested by Sauer had toxicity that was reduced by aeration. However, it is important t o note that the aeration step in the TIE is not as efficient as air stripping
treatment.
Hand stated that benzene, toluene, naphthalene, phenanthrene, anthracene, pyrene, phenol can be removed effectively.
May not need high removal efficiencies t o remove the toxicants t o non- toxic levels. Also maybe just treat part of the waste stream.
High temperature should increase the removal of semi-volatiles by stripping.
Very little data on Henry's Law Constants at elevated temperatures.
2. Is additional chemical usage necessary t o reduce toxicity?
Acid and base addition is necessary for H,S and ammonia removal, respectively.
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Possible precipitation of inorganics such as calcium and magnesium.
Can continuously add acid to feed or periodically acid wash tower.
produced water is unstable. Temperature will change and precipitates will form from contact with air.
3. What range of oil and grease and salinity can the technology tolerate?
Salinity increases the Henry’s Law Constant by 20 t o 30% which will increase stripping efficiency.
Definition of oil: Dispersed versus soluble (dissolved). Measured gravimetrically or by IR.
Oil may coat the packing and change surface tension of packing.
Unsure of overall effect. May cause accumulation of suspended solids.
4. What are the equipment specifications?
Minimal pumping requirements.
Not a power intensive process. Need a 1 to 5 hp blower for 5 0 t o 1,500 gpm flow rate.
Air t o water ratio of 5 0 v/v.
Low operating pressure tower. Could be fiberglass or PVC.
Maybe use aerated tank instead of packed tower, especially if precipitation is a problem.
For 15,000 bbl/d (440 gpm) flow rate, 4 t o 5 diameter tower, 1 O t o 20 f t height (height will depend on temperature effect and desired removal efficiency).
Space: 20 sf for tower and 20 sf for blower etc.
Need separate off-gas vent.
May need t o put demister on off-gas vent because of condensate formation related t o temperature difference between air and produced water.
May need equipment for off-gas capture and treatment (e.g., scrubber).
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API DR*35L 96 = 0732290 0553727 355
5. What is technology’s current operational state (Le., pilot, laboratory-scale or full-scale)?
Many commercial applications.
None for produced water treatment.
6. What is the potential for technology improvements (¡.e., many versus few, rapid versus slow).
Need to optimize for specific applications.
Potential for improvements is slow, although there have been recent advances in packing material.
7. Are there any toxicity reduction performance data?
TIE work on produced water, especially in Wyoming, shows that
toxicity can be removed by aeration. In these cases, toxicity is probably due t o H,S.
Sample integrity is important for TIE or treatability testing. Use sample collected in the same way as for toxicity compliance tests. For
example, samples exposed t o air during shipping may not have same toxicity as produced water discharged directly t o receiving water.
8. List the advantages and disadvantages with regard t o weight, size, energy requirements, produced water residence time, throughput capacity,
inputlloading rates, operating temperatures, waste stream types, fouling potential and scaling potential.
Size: small footprint; 20 sf for tower and 20 sf for blower etc.
Weight: low.
Energy Requirements: low, 1 t o 5 hp blower.
produced water Residence Time: up t o 1,500 gpm flow rate.
Operating Temperatures: High temperature ( 1 4OOF) should increase removal efficiencies.
Waste Stream Types: off-gas may be a problem if treatment is required for air pollution regulations.
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A P I DR*351 96 m 0732290 0553728 291 m
Fouling: maybe b y oil.
Scaling: Iron and calcium precipitation.
Not manpower intensive, simple t o operate.
No chemicals needed except maybe acid and base for H2S and ammonia removal, respectively.
Well k n o w n technology