Oily Wastewater Treatment Process for Heavy-Oil Power Plants
Heavy-oil power plants generate electricity with heavy oil as fuel. Besides exhaust pollution, their operation also produces oily wastewater. The wastewater mainly comes from oil tank cleaning, pipeline leaks, equipment washing and lubricating oil mixed in from the coal handling system; its composition is complex and treatment is difficult: heavy oil coexists with light oil, the small treatment volume restricts the use of high-efficiency regeneration technologies, and emulsified oil makes natural settling difficult. Although the oil content is not high, discharge without treatment would severely damage the downstream sewage treatment system.
Limitations of existing technologies
Composite settling tank + high-clarity filter method: relies on chemicals for settling, but has a large footprint, high cost and low automation, requires manual sludge removal and carries safety and environmental risks.
Oil separation tank + flotation tank + filtration system: conventional flotation gives unstable removal of emulsified oil and high-density oil droplets and easily clogs filters, facing the same footprint and cost problems.
Oil-water separator: as oil and water densities are close, gravity separation is inefficient and poorly resistant to fluctuation; the equipment has a large footprint, the packing clogs easily and performance is insufficient.
Therefore, developing an efficient, environmentally friendly and economical treatment technology has become an urgent need.
Innovative process scheme
To address these problems, SINOKLE adopted a technology centred on the CDFU cyclonic dissolved air flotation, forming the heavy-oil power plant oily wastewater treatment process.
Process flow diagram of oily wastewater treatment for heavy-oil power plants
The scheme has been successfully applied at the Sierra Leone heavy-oil power station (total installed capacity 43.65 MW). The wastewater there features high heavy-oil density, high viscosity and severe emulsification; through two-stage CDFU units, oils and suspended solids are effectively removed, treating oily wastewater from the main power house, oil pump house and tank farm to ensure compliant discharge. A Bangladesh fuel power station project commissioned in 2021 also verified the reliability of this process.
Wastewater treatment system at a heavy-oil power plant in Bangladesh
Technical advantages
Efficient and stable: significant oil and suspended solids removal, strong shock resistance, stable compliant effluent;
Environmentally friendly and economical: short process flow, mainly physical, little oily sludge, low operating cost;
Compact and intelligent: skid-mounted design is compact and lightweight, greatly reducing footprint; automated control lowers the intensity of manual operation;
Mature and reliable: verified by projects at home and abroad, minimising operational risk.
This process solves the difficult problem of oily wastewater treatment in heavy-oil power plants, combining technical advancement with engineering practicality.
