Investigation Of Micro-Emulsified Fuel Based On Methanol And Low Temperature Coal Tar

As the post-oil era has arrived, the growing shortage of oil resources leads to the crude oil prices large fluctuations. In recent years, water-in-diesel emulsions, methanol–in–diesel oil emulsified fuel have been developed rapidly due to the advantages of its fuel-efficient and reducing the pollutant emissions, and have been applied in a certain range. However, because there were a lot of problems, such as the nature of unstable and being eventually separated, shorter storage time and combustion instability and so on, the popularization and application of emulsified diesel oil was still very limited. Micro–emulsion diesel fuel as a better energy conservation and environmental protection fuel has got more and more attention, for it can solve the problems existed in emulsified diesel fuel. In this paper, low temperature coal tar and methaol were selected as substituted materials to make micro-emulsion diesel fuel. The pre-processing for low-temperature coal tar is necessary and the oil obtained from the distillation of low-temperature coal tar was refined, and the compound emulsifier system was studied; Some properties of micro-emulsion were determined, and the cost of the micro-emulsion were also analyzed.According to the formulation principle of surfactants, several common emulsifier were mixed to find the best compound emulsifier for the diesel oil–methanol–refined tar micro-emulsion system. The compatibility of refined tar, methanol and diesel oil and the best HLB value in different oil/methanol proportions were investigated. The solubilization effect of medium-chain fatty alcohol, the relationship in critical temperature, amount of co-solvent and emulsifier and its effect on the droplet size were also studied. The corresponding results indicated that the refined tar could miscible with diesel oil only in a certain proportion, but the solubility with methanol was greater, and achieved about 46 percent. The best HLB value in different ratio of raw materials systems were different, and the best HLB value of M20D40C40, M30D35C35 and M40D30C30 sytems were 5.0, 4.5 and 4.0 separately. N-pentanol had the best efficiency of solubilization in the selected cosolvent, and the compound of anionic surfactant oleic acid and non-ionic surfactant OP-10 had the best emulsification effect. As the amount of cosolvent and emulsifier changed, the temperature forming thermodynamic steady micro-emulsion was varied, and the droplet size also changed greatly; as the amount of emulsifier increased, the critical temperature forming thermodynamic steady micro-emulsion was lower, and droplet size was smaller; cosolvent played an important role in reduceing the surface tension and droplet size.Some properties of micro-emulsion were determined, such as the calorific value, viscosity, copper corrosion, flash point and the type of micro-emulsion. The results showed that all the calorific value of prepared micro-emulsion fuel were more than 8000 kcal/kg and can meet the requirement of commercial alternative fuels; methanol content, temperature and amount of emulsifier have impact on viscosity, as the temperature and methanol content increased, the viscosity of micro-emulsion decreased, and with the increase of the emulsifier amount, the viscosity increased: under the same conditions and in the 15.0℃, the viscosity of micro-emulsion with 3% emulsifier was 4.0 mp?s while that of with 4% emulsifier micro-emulsion was 5.0 mp?s. The copper corrosion results indicated that: the micro-emulsion fuel corrosion did not reach the fourth class and were full compliance with the standards of corrosive; Flash point test results showed that the prepared micro-emulsion with lower flash point of diesel oil, and the flash point of M10 sample was only 25℃; external phase dilution method and CoCl2 test paper results proved that all of the prepared micro-emulsion types were W/O.From combustion experiment can be seen that an insignificant difference between pure diesel and micro-emulsion diesel oil burning rate, but the release rate of soot were less than that of pure diesel oil; the micro-emulsions were transparent and the stable time could keep at least 3 months at constant temperature.The cost of the micro-emulsion accounting showed that cost of M10, M20, M30 and M40 micro-emulsion samples were 3600, 3671, 3685 and 3692 RMB/t separately, and all were lower than the market price of pure diesel oil.