An Efficient Process for Electric Desalting Wastewater Treatment
1. Sources of electric desalting wastewater
Crude oil contains a certain amount of salts, such as sodium chloride, magnesium chloride and calcium chloride. As water evaporates, salts form scale on the walls of heat exchangers and furnace tubes, reducing heat transfer efficiency and increasing flow resistance; in severe cases this leads to pipeline blockage, tube wall burn-through and accidents. Metals in the salts enter heavy distillates or residue, poisoning catalysts and affecting the quality of secondary processing feedstock and of the products. Therefore, after crude oil enters a refinery it must first undergo desalting so that the salt content is < 5 mg/L; for refineries with residue hydrotreating or heavy oil catalytic cracking, the crude oil salt content is required to be < 3 mg/L. Electric desalting wastewater refers to the oily and saline wastewater discharged after crude oil enters the electric desalting unit for desalting and dehydration.
2.Generation ofelectric desalting wastewater
To remove salt particles suspended in the crude oil, a certain amount of fresh water is injected into the crude oil (typically at 5%), together with a demulsifier, which helps break the emulsifying film in the emulsifier. After the crude oil is thoroughly mixed with the fresh water and demulsifier, it enters the electric desalting unit; under the action of the electric field, tiny water droplets coalesce into larger droplets and, under gravity, the oil and water separate. The water is then drawn off from the electric desalting unit. The quality of electric desalting wastewater depends on the properties of the crude oil and the amount of fresh water injected; generally, the petroleum-based content in electric desalting wastewater is about 200 mg/L and the conductivity about 2000 microseconds/cm.
3. SINOKLEelectric desalting wastewaternew treatment process
Because the dissolved oil, emulsified oil and smaller-particle waste oil that the wastewater may contain cannot be well removed, SINOKLE has combined its independently developed technologies to propose a new process to solve these problems.
SINOKLE's new process for electric desalting wastewater treatment
CDFU: cyclonic dissolved-air flotation is a new-generation green and highly efficient vertical-tank air flotation device developed by our company. The device integrates cyclonic centrifugal separation technology, ultra-fine bubble generation technology and dissolved-air flotation technology, and through the organic combination of multiple technologies achieves efficient and rapid separation of waste oil, emulsified oil and suspended solids in wastewater. The oil removal rate of this device is > 90% and the SS removal rate > 85%; it uses purely physical means for demulsification; the equipment is skid-mounted, automated and digitalised and can provide remote expert services; and it operates enclosed under pressure, making it safe and environmentally friendly.
High-efficiency coalescing oil separator: a patented product of our company, it uses the coalescence principle, the shallow-pool principle and CFD simulation tools to optimise the internal space and structure of the tank and rationally arrange the internal flow field, achieving rapid agglomeration, coalescence, flotation (or settling) and separation of oil droplets or suspended solids in water. The equipment has a compact structure, a small footprint and high oil removal efficiency (> 90%); the internal packing adopts a patented structural design and is available in stainless steel or reinforced PP, with high strength and long service life; the specially designed sand-flushing and sludge-discharging device keeps both the packing and the equipment free from clogging; and it operates fully enclosed, under pressure and automatically, running smoothly, safely and reliably.
Coalescing pressure oil separator project site
4. Commissioning and application of electric desalting wastewater treatment projects
Project treatment data: influent oil content: <= 20,000 ppm; effluent oil content: <= 500 ppm
