TREATMENT OF EFFLUENTS FROM PETROLEUM REFINERIES

By- Asheesh Padiyar (1RV12CH006) Department of Chemical Engineering R.V College of Engineering

TECHNICAL SEMINAR ( 12CH82 )

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A petrochemical Refinery

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JUSTIFICATION

• Petroleum refinery effluents (PRE’s) are major source of aquatic environmental pollution (Oil, Grease and other toxic organic compounds)

• Crude oil remains to be the most important raw material. Around 44 % increase in production in next 20 years, which makes processing of crude oil and PRE handling globally important issues[1]

• Processing of crude oil consumes a lot of water, studies have showed that the volume of PRE’s generated is 0.4-1.6 times the crude oil processed[1]

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OVERALL REFINERY WATER BALANCE

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CONTIMINANTS IN RAW WATER AND METHOD FOR REMOVAL• Turbidity- Coagulation, settling filtration

• Hardness- Softening, distillation, surfactants

• Alkalinity- Lime treatment, anion exchange

• Oil- Oil/water separators ,coagulation , filtration

• Dissolved solids- Softening processes

• Suspended solids-Sedimentation ,filtration

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PROCESS WATER

Water that has been in intimate contact with the hydrocarbons in the refinery.

• Desalter effluent• Sour water• Tank bottom draws• Spent caustic

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DESALTER

• Prevent fouling

• Reduce corrosion caused by formation of HCl

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Typical desalter unit configuration

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SOUR WATER

• Steam is used as a stripping medium and as a diluent to reduce the hydrocarbon partial pressure in catalytic cracking and other applications.

• Steam is condensed in presence of hydrocarbons which contain hydrogen sulphide and ammonia hence requiring pretreatment before reuse.

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Sour water stripper configuration

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TANK BOTTOM DRAWS

• The incoming crude to refineries normally contains water and sediments (mud) that are picked up when the oil is extracted from the wells—this is referred to as bottom sediment and water (BS&W).

• When the crude is stored in large tanks, the BS&W settles to the bottom and must be periodically removed.

Crude tank water draw

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DESALTER EFFLUENT TREATMENT

• Desalter oil/water separation- Inorganic salts are present in the crude oil as emulsified solution of salt. The amount of water received at the refinery with crude is about 0.1 -2.0 % by volume.

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• Desalter effluent stripper

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SEQUENCE FOR TREATING PRE’s

[3]

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• Primary treatment

API separator

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Dissolved air floatation system

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• Secondary treatment

1. Suspended growth process A. Activated sludgeB. Aerated lagoons

2. Attached growth process

C. Trickling filtersD. Rotating biological contactors

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Activated sludge system

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Trickling filter

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• Tertiary treatment

• Total suspended solids (TSS)

• Chemical oxygen demand (COD)

• Dissolved and suspended metals

• Trace organics such poly-aromatic hydrocarbons (PAHs)

Effluent from the biological treatment system typically contains about 25 to 80 mg/l of suspended solids depending on the operating conditions in the clarifier. Refineries at many locations need to meet limits as low as 15 mg/l on a consistent basis.[2]

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Sand filtration

Anthracite Coal

Sand

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NEED FOR POSSIBLE NEW TECHNOLOGIES

Several advancement have been made to improve performance ranging from bio-augmentation to fluidized bioreactors. However, the problems of high sludge generation, low tolerance to toxic load and organic shock coupled with a slow degradation rate persist. Other methods are either require extreme temperature and pressure operating conditions or cannot handle large volumes of refinery waste waters effectively.

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• Reverse electro dialysis (RED)

• Photocatalytic degradation A process that potentially mineralizes all of the organic and inorganic components typically found in the refinery effluent to environmentally benign by-products

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References1. “Petroleum refining water/wastewater use and

management”- IPIECA 2. Basheer Hasan Diya’uddeen “Treatment technologies

for petroleum refinery effluents: A review” Process Safety and Environmental Protection 8 9 (2011) 95–105

3. Javad ,” Organic Pollutants Removal from Petroleum Refinery Wastewater with Nano-titania Photo-catalyst and UV Light Emission” International Journal of Photo-energy ,Volume 2012

4. Felipe Pombo, “Technology Roadmap for Wastewater Reuse in Petroleum Refineries in Brazil”, Journal of Environmental Management in Practice, DOI: 10.5772/20297

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THANK YOU