Pretreatment of super viscous oil wastewater and its application in refinery

Wastewater from super viscous oil processing cannot be effectively treated by conventional wastewater treatment plants in refineries because of its high concentration of various organic pollutants. In order to resolve this problem, a number of investigations were conducted in our work to understand the physicochemical properties, sedimentation, demulsification and pretreatment of such super viscous oil refinery wastewater. The results showed that the key issues for pretreatment of this wastewater were： （1） Optimized process parameters were used in the sedimentation and demulsification processes for oil removal to effectively recover oil and remove scum from wastewater; （2） A suitable flocculation process was selected to minimize oil, suspended solids （SS） and chemical oxygen demand （CODcr）. A pretreatment process including three continuous steps： oil removal by sedimentation, oil removal by demulsification, and flotation separation, was proposed and applied in Liaohe Petrochemical Company, PetroChina and the oil content in effluents was less than 200 mg/L and CODcr less than 2,500 mg/L, which completely met the requirement for influent of the conventional wastewater treatment plant, and the recovered super viscous oil reached 5,873 tons in the initial year in Liaohe Petrochemical Company, PetroChina.

Causes Leading to Formation of Shot Cokes and Measures for Its Prevention in Super Viscous Oil Delayed Coking Unit

Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.

Speed up the absorption of viscous crude oil spill by Joule-heated sorbent design

Although ocean crude-oil spill accidents did not frequently happened in the past, it really caused great damage to the ma- rine ecosystem once it happened. Because of the spreading and weathering, crude-oil spill usually covers a large area of water surface and its viscosity is very high, which brings hu- man great trouble to clean it up. Dispersant and in-situ burn- ing were frequently used in the past crude-oil spill accidents, but these two methods suffered from the drawbacks includ- ing being toxic to marine lives, causing air pollution, disabil- ity of recovering the crude oil. Oil skimmers could recovery the oils, but their handling capacities are rather limited. Re- cently, porous hydrophobic and oleophilic materials （PHOM） have been demonstrated as low-cost, efficient and ecofriendly materials for the oil spill cleanup [ 1 ]. Nevertheless, their poor absorption speed to viscous oil spill hinders their practical ap- plication.

PREPARATION OF HIGHLY BRANCHED POLYETHYLENE WITH ACENAPHTHENEDHMINE NICKEL CHLORIDE/DIETHYLALUMINUM CHLORIDE CATALYST

The homogeneous catalyst system [ArN C（Nap）-C（Nap）=NAr]NiCl2 （Nap = 1,8-naphthdiyl, Ar = 2,6- diisopropylphenyl）/AlEt2Cl has been prepared and examined for ethylene polymerization. Polymerization conditions such as cocatalyst, Al/Ni molar ratio and polymerization temperature （Tp） have a great effect on catalytic activity and properties of polyethylenes （PE）. The activity of 5.1 × 10^5g PE/mol Ni. h was obtained by the catalyst, activated with AlEt2Cl at 120 of Al/Ni ratio and 30℃. Especially, Tp had a pronounced influence on branches and molecular weight of PE. Branching degree of PE increased with increasing temperature whereas their molecular weight decreased correspondingly. At Tp lower than about 70℃, the resultant PE was an elastic material. When Tp was higher than 70℃, the product was a viscous oil. The resultant PE was confirmed by ^13C-NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl, amyl, and longer branches （longer than six carbons）. According to gel permeation chromatographic measurement, the weightaverage molecular weights of the polymers obtained ranged from 3.6 × 10^3 to 2.3 × 10^5.