A Comprehensive Solution for Oily Wastewater Challenges in Light-Oil Tank Farms of Thermal Power Plants
A thermal power station, commonly called a fossil-fuel power plant, is a facility that produces electricity by burning combustibles such as coal, natural gas and petroleum. Its basic principle: the heat generated by fuel combustion heats water and converts it into steam, transforming chemical energy into thermal energy; steam pressure drives the turbine, converting thermal energy into mechanical energy; the turbine then drives the generator, ultimately converting mechanical energy into electrical energy. Depending on the fuel used, such plants can be classified as coal-fired, oil-fired, gas-fired, waste-heat recovery, and waste/industrial byproduct-fueled types.
As the main source of electricity supply in today's society, and under the era's requirements of building a harmonious society and developing a circular economy, the development of thermal power technology must pay close attention to its impact on the ecological environment and its consumption of non-renewable resources.
In the daily operation of a thermal power station, besides the waste gas pollutants from fuel combustion, the generation of various oily wastewaters is hard to avoid. These wastewaters mainly come from: cleaning water for fuel storage tanks, leakage and flushing water from oil pumps and pipelines, lubricating grease mixed into water in the coal handling system, and oily sewage discharged from other areas (such as pump houses, motor pumps and metering units).
Such wastewater is complex in composition and difficult to treat, specifically:
Crude oil is divided into heavy oil and light oil;
The treatment volume is small, so regeneration processes are not feasible;
It contains a certain amount of emulsified oil, which is difficult to separate by settling;
Coal-washing wastewater has a low oil content, many suspended solids and a large amount of residue.
Although the oil concentration of these wastewaters may be only a few hundred milligrams per liter, improper disposal will impose a serious shock load on the downstream wastewater treatment system, greatly affecting the stability of the treatment process and the final discharge compliance rate.
Common oily wastewater treatment processes in power plants currently include:
1. Composite settling tank + high-definition filter process. This process mainly relies on chemicals and settling to remove oil and suspended solids. It has a large footprint and high land and infrastructure costs, poor adaptability to working conditions—especially weak shock resistance—low automation, difficult oil recovery, requires periodic manual tank cleaning, is difficult to operate, and poses safety and environmental hazards.
2. Oil separation tank + flotation tank + filtration process. The conventional flotation tanks used in this process cannot remove emulsified, high-density oil droplets, so treatment performance is poor; they cannot adapt to conditions with high and highly fluctuating oil content, and the effluent carries oil and is unstable; the flotation effect is insignificant, which easily causes the filter to clog; the footprint is large, with high land and infrastructure costs.
3. Oil-water separator process. Because the densities of oil and water are close, gravity separation alone cannot meet effluent requirements; it has poor resistance to fluctuation and unstable effluent; the residence time is long and the footprint is large; conventional packing gives poor coalescence performance and easily clogs.
To solve the problem of oily wastewater treatment in thermal power plants, SINOKLE, combining its core patented products such as the KHC coalescing oil remover, has developed a process scheme for oily wastewater treatment in light-oil tank areas of thermal power plants tailored to the characteristics of different types of thermal power plant wastewater. The process diagram is as follows:
Process scheme for oily wastewater treatment in light-oil tank areas of thermal power plants
This process has strong shock resistance, high efficiency and stable effluent, thoroughly solving the problem of oil depot wastewater discharge. The process flow is short and mainly physical, with stable performance and little oily sludge—an environmentally friendly technology; it runs fully automatically in an enclosed mode with a small footprint, requiring little labor and maintenance and easy operation; it incorporates multiple domestically leading patented technologies and is technically advanced.
Application case of oily wastewater treatment in thermal power plants:
In March 2024, the oily wastewater treatment system custom-built by SINOKLE for a large combined heat and power project in Shaanxi Province was successfully commissioned. Testing showed that the effluent quality steadily met the design standards, achieving the expected treatment results and successfully solving the project's oily wastewater treatment challenge.
The project adopted a combination process of SINOKLE custom filters and a high-efficiency coalescing pressure oil remover, with a design treatment capacity of 10 cubic meters per hour. The oily wastewater first passes through the filter to remove suspended solids and waste residue, then enters the high-efficiency oil remover for deep oil-water separation; the final effluent is clear and transparent and complies with relevant national discharge standards.
Oily wastewater treatment equipment of the combined heat and power project
The high-efficiency coalescing pressure oil remover is a patented product of SINOKLE. Using the coarse-graining principle, the shallow-tank principle and CFD simulation tools to optimize the internal space and structure of the vessel and rationally arrange the internal flow field, it enables oil droplets or suspended solids to quickly gather, coalesce, float (or sink) and separate in the water. The interior of the vessel consists of an inlet pre-separation zone, an initial separation zone and a main separation zone. The inlet pre-separation zone consists of specially designed swirl separation devices; the initial and main separation zones are filled with coalescing packing of different specifications; an oil collecting sump is provided at the top of the vessel, and an efficient sand-flushing and desilting device is installed at the bottom.
Comparison of influent and effluent (left: influent; right: effluent)
The high-efficiency coalescing pressure oil remover has the following technical advantages:
Compact structure and small footprint, with oil removal efficiency above 90%;
The internal packing adopts a patented structural design, made of stainless steel or reinforced PP, with high strength and long service life;
A specially designed sand-flushing and desilting device is installed inside the oil remover, so the packing does not clog and the equipment does not silt up, allowing long-term stable operation and reducing maintenance work;
The oil remover runs fully enclosed and pressurized automatically, with stable, safe and reliable operation and no safety or environmental risks.
Numerous successful applications at home and abroad prove that SINOKLE's oily wastewater treatment process for thermal power stations operates stably and reliably, with long equipment service life, high oil removal efficiency and continuously compliant wastewater treatment results, providing an effective solution for power station wastewater management.
