Oil removing pretreatment technology for petroleum oil refining wastewater

Abstract

The invention discloses an oil removing pretreatment technology for petroleum oil refining wastewater. According to the oil removing pretreatment technology, a water collecting tank with gratings is used for separating sand and sludge; a three-phase cyclone liquid separation floating oil collecting and discharging adjusting tank is used for achieving separation of water, oil and residues; a cyclone oil coarse graining polymerization oil-water separator is used for removing fine oil grains; a dissolved air flotation device is used for demulsification and flocculation reaction, wherein air bubbles and suspended solids in wastewater make contact for adhesion and float upwards, and the standard is met through residue scraping. The technology is simple, the structure is scientific, the three-phase cyclone liquid separation floating oil collecting and discharging adjusting tank, the cyclone liquid coarse graining polymerization oil-water separator and the dissolved air flotation device jointly serve as the core treatment scheme, oily wastewater is pretreated through the density difference of oil and water based on the fluid dynamics principle, a physical method and a chemical method act jointly, and the oil content in the pretreated oily wastewater is smaller than or equal to 20 mg / L and reaches the standard. The oil removing pretreatment technology is large in daily treatment amount, high in oil removing efficiency, remarkable in oil collecting effect and considerable in economic benefit, and the water content of the recycled waste oil is 5% or lower.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a process for deoiling pretreatment of petroleum refinery sewage. Background technique [0002] The sewage after oil extraction mainly comes from different sections such as drilling, oil production, well washing, downhole operation, oil refining, and chemical industry. The wastewater discharged from these sections contains petroleum, volatile phenol, sulfide, SS and other pollutants. The discharged wastewater contains The highest oil content is about 10000mg / L, and the highest suspended solid content is about 600mg / L, which respectively exceed the specified indicators in the SY / T5329-94 standard (oil content≤20-30mg / L, suspended solid content≤10mg / L), The oily substances in oily wastewater float on the water surface, forming a thin film, which can prevent the oxygen in the air from dissolving in the water, reduce the dissolved oxygen in the water, and hinder t...

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Problems solved by technology

[0003] At present, sewage treatment generally requires a pre-oil removal process first. The main treatment methods for pre-oil removal generally include physical treatment and chemical methods: chemical methods are treated by adding demulsifiers and flocculants, but this type of technology The ideal degreasing effect cannot be achieved, and the oil cannot be recovered. Especially for sewage with serious emulsification, the demulsification cannot be achieved only by adding a demulsifier, and the fundamental problem cannot be solved. Moreover, the pre-degreasing does not meet the requirements, and it also causes secondary demulsification of the water body. Pollution not only increases the treatment cost of downstream sewage treatment, causes certain pollution to the environment, but also causes waste of resources. Physical methods include adsorption method, membrane filtration, electromagnetic adsorption, air flotation method, gravity separation and other methods. Each has its own advantages but cannot Completely control the oil content in the sewage below 20mg / L, which will increase the cost and time of the subsequent process. The existing sewage pre-greasing equipment can no longer meet the production needs. The purpose of the oily sewage pretreatment is to meet the final discharge standard. There are A large amount of oily substances, the raw water of the process water is desalinated water, which has a high reuse value. The sewage and the oil in it are recycled, and the suspended solids and sediment in the sewage are removed, so that the sewage treatment station Conveying sewage reaches the specified standards and meets the needs of oilfield production, which can not only save water resources, but also save costs and improve efficiency for enterprises

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