| Petroleum is a nonrenewable resource that people eager to expand reserves in order to meeting increasing domestic demand, so its stocks are declining. High pour point crude oil has brought great difficulties for exploration and transportation. Nowadays main way are chemical and physical method for solving this problem, then chemical way is widely uesd because of its low energy consumption and simplicity of operation. As adding the chemical pour point depressant (PPD) to the crude oil is the most effective method to reduce the pour point of crude oil. With a small amount of pour point depressant can largely modify wax crystal configuration. There are many kinds of pour point depressant, just as EVA with their modified content、combshaped polymer、amido acid salt copolymer type、alky aromatics type, of which acrylate combshaped copolymer are widely used and researched.The investigative subject of this thesis is the Nanyang crude oil. This article analyzes the oil composition and property, ensures the molecular structure of PPD、 compounds and filters PPD in order to choose the most effective this kind of PPD on crude oil. There are four sections during the paper.The first part is proximate analysis and physical property testing on18oil from Nanyang oil field. Reference to the standard SY/T5519-2008, the experimental project is figured out and calculates quantitative contents by isolating aturate、 aromatic、colloid and asph altene. Wax is isolated by the technique that is ascertained reference standard SY/T0537-2008and content of carbon number is measured by gas chromatography. The freezing points are measured by the mean reference standards GB510-83and SY/T0541-1994. With analyzing and comparing the relations of four component contents、the freezing point and the wax content of crude oil, there are great correspondence among wax content, content of high carbon number hydrocarbon and solidifying point. It could be found that the content of wax is higher and six hydrocarbons are more, their freezing point are higher.The synthesises and elections of polymers are the second part. Firstly, the length of alkyl carbon chain, the polar group and the kinds of monomers are ensured according to analyzing the composition of the crude oil、the carbon number and the work mechanism of PPD. Ssome polymers are synthesised by styrene、vinylacetate and ester be made of acrylic acid and docosyl alcohol/stearyl alcohol. The products are octadecyl acrylate(Am)、polyacrylate behenyl(Dm)、octadecyl acrylate-styrene (AmS)、docosane acrylate-styrene(DmS)、octadecyl acrylate-vinyl acetate-styrene (AVS) and docosane acrylate-vinyl acetate-styrene(DVS). Ensure the formation of the desired product be dimer or trimer and their identification are based on spectroscopic methods.Chooseing the best PPD from six kinds of polymer by determining excellent effect for hydro-cracking on Weigang V-296crude oil, make sure that the ideal PPD are octadecyl acrylate-vinyl acetate-styrene(AVS) and docosane acrylate-vinyl acetate-styrene(DVS). Then, these are chosen by experiment and document that the appropriate dissolvant, catalyst, reaction time, monomer ratio, initiator amount and reaction temperature etc and the synthetic condition of the two polymer are discussed by orthogonal test. The optimal synthetic condition of AVS is determined as follows: the best molar ratio of A, S and V is2:1:2, the dosage of initiator is1.2%, the monomer concentration of the reaction is30%and the reaction time is7h. The optimal synthetic condition of DVS is determined as follows:the best molar ratio of D, S and V is2:1:2, the dosage of initiator is0.9%, the monomer concentration of the reaction is30%and the reaction time is7h. When the dosage of AVS/DVS is0.5%, the freezing point of Nanyang crude oil can be reduced7℃and8.5℃.The third part is to analyze external and internal causes on the pour point depression performance. Toluene is great diluent, which has good dissolvability and effort on pour point depresion; The most suitable temperature is80℃and the great dosage is0.5%. It has great effort when the wax content is lower(<20%), the asphaltene content is lower(<20%), the colloid content is more and the content of high carbon number is higher; The result is that compound can make freezing point depress52℃; it has better effort when the molecular weight of polymer is more.The last section is compound PPD with polymer. Main conclusions are:(1) By comparing depressive effect and inhibiting rate of two kinds of low molecular weight T8under different dosages, T82has better effort so that is treat as complex pour point reducer.(2) It is important to compound AVS/DVS and T82so as to find out the suitable ratio. The conclusion is that the best ratio of T82:AVS/DVS is1:2. When the temperature is80℃and the dosage is0.5%, compound can make the pour point of crude oil decrease8.5℃and10℃.(3) The effect of compound PPD is ensured by testing effect of pour point reducer. It could be found:For most of18kinds of crude oil, the best composite reagents have better adaptability and depressive effort than siple dosage.(4)By contrasting with depressive effect and inhibiting rate of siple dosage, industrial chemicals and composite reagent, an in-depth analysis of the financial situation will reveal:At the same dosage0.3%, inhibition rate of industrial chemical and composite reagent respectively are21.98%and40.62%. Comparing with industrial goods, composite reagent is more easily to crystal with wax, adsorb and prevent wax from precipitation. |
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