Preparation And Application Of Emulsified Diesel Prepared By Ultrafiltration Membrane

As a alternative fossil fuel, w/o emulsified diesel oil was made up of diesel oil, water, emulsifier and some additives. Emulsification of diesel oil is an effective method to conservate energy, discharge pollutants, solve the problems of shortage of crude oil resources as well as environmental pollution and improve the availability of diesel oil.As we have known that the emulsifiers are usually selected according to the rule of Hydrophile-Lipophile-Balance value and the emulsifiers are made of several kinds of surfactants. The factors that influence the stability of emulsified fuel are discussed in this paper. The methods of UF membrane, homogenization and agitatation were used to prepare w/o emulsified diesel oil, respectively. Then we discussed the influence of different preparing methods on the stability of emulsion and compared the dosage of emulsifier at the same quality of emulsion. In addition, the influence of operating parameters, such as emulsifier dosage, shear stress, trans-membrane pressure and emulsification temperature, on emulsion properties were also discussed. Further, we studied the effect of Dean vortex during emulsification, then investigated the influence of model parameter, such as diameter of coiled membrane and pitch of coiled membrane on emulsion properties, and the effect of Dean vortex on strengthening shear stress, weakening membrane pollution, improving membrane flux was discussed. Finally, by studying the influence of operating parameters, such as operating manner, trans-membrane pressure, temperature, velocity of continuous phase, on membrane flux and membrane resistance value, we obtained the optimized conditions of emulsification. And by considering the deduce of membrane flux, the method of membrane flux recovery was studied.The prepared diesel emulsion demonstrated 200%-250% longer stability and 50%-65% less emulsifier consumption compared with those prepared with traditional methods, such as high speed homogenization; emulsified diesel with nanoparticle sizes of as small as 30-65 nm and a distribution coefficientαof 0.12-0.3 could be obtained at a trans-membrane pressure of 0.02 MPa and a cross flow rate of 2.0-5.0 m/s with the emulsifier higher than 0.5 wt% ;During the preparing of w/o diesel emulsion, Dean vortex effect could improve the quality of emulsion effectively. The influence of diameter of coiled membrane and pitch of coiled membrane on Dean vortex was different, and the diameter of coiled membrane was more effective. Dean vortex could restrain the formation of membrane pollution effectively, and the membrane flux of spiral membrane was 250 % higher than that of the corresponding straight membrane. During the process of industrial production, trans-membrane pressure of 0.12 MPa, emulsification temperature of 25℃and cross flow rate of 0.66 m/s were determined as the optimized emulsification conditions. After the membrane flux reduced, we back-purged it with pure water, and then immersed it in a alkali solution with pH value at 12 for 30 minutes followed by pure water with 1% degreasing emulsifier for 30 minutes. Finally, the membrane was immersed in alcohol for 1.5 hours. Then the membrane flux recovery ratio can reached 90%.