Study On Demulsification And Purification Technology For Wastewater From Heavy Crude Oil

The purpose of this thesis is to treat Liaohe heavy crude oil sewage with the demulsification and flocculation.The high-speed camera(CCD) is applied to observe the emulsion demulsification process of heavy crude oil.Finally,the demulsification mechanism of the heavy crude oil emulsion is analyzed.12 kinds of commercial demulsifies are adopted respectively at dosage of 0.3g/L to demulsify the emulsions at 60℃.For all these demulsifies,the dehydrated rates of the Oil-in-Water emulsions are quite low and the separated water is rather cloudy.A binary combination,THG-A2/SP-2 is shown to be most effective.After emulsion of 120min,the dehydrated rate is 98.7%and the separated water is limpid.The optimal operating parameters are as followed.The mass ratio of THG-A2 to SP-2 is about 1:2.The combinational demulsified dosage is 0.3～0.35g/l.The dehydration temperature is 60～65℃.For Liaohe heavy crude oil sewage,treatment experimental results show that the degreasing rate reaches 88.76%,the turbidity removal rate is up to 99%,the suspended solids removal rate reaches 83.48%,the COD removal rate reaches 99.69%.The oil group compositions of the heavy crude oil before demulsification and flocculation treatment are 4.19%of wax,37.8%of aromatics,31.14%of microglia,and 0.86%of asphaltenes.The compositions of heavy crude oil after flocculation demulsification are 4.53%of wax content,38.19%of aromatics content, 30.45%of the glial content,and 0.75%of asphaltene content.Those show that the basic composition has not changed after demulsification and flocculation.In addition,the demulsification process of the heavy crude oil emulsion is observed through CCD to analyze its demulsification mechanism.The results show that demulsification process begins with the droplet aggregation,appropriate temperature on the emulsion broken is necessary.Variation of interfacial tension reflects the adsorption of demulsifier molecule on the interface.As a result,the interfacial tension determines the demulsification rate,but can not be used to forecast the demulsification efficiency.The emulsion dehydration rate depends on the intensity of interfacial film primarily.