Study On The Causes And Prevention Of Carbon Deposit Formation In Compound Biodiesel Of Vegetable Oil

Biodiesel is a green energy that can replace fossil diesel.Traditional biodiesel is preparated by esterification reaction,using methanol or ethanol to replace the glycerol of vegetable oil.Due to the complexity?energy consumption and high cost in the production process,so that the application and its promotion have been hampered.In order to break the cost bottleneck,compound biodiesel is the best choice.Compound biodiesel is obtained by adding cetane number improver and viscosity adjusting agent in vegetable oil.The preparation process is simple and the production cost is low,which is expected to achieve market promotion.However,because of it's the complex of composition?the high of average molecular and the high degree of unsaturated number and so on,it is easily lead to oxidation polymerization.After long-term use of the biodiesel,carbon deposition is easily produced in the cylinder,fuel injectors,valves.The study on the causes and prevention of carbon deposition formation will make farreaching significance in the realization of using compound biodiesel as the diesel fuel,and the promotion and application of developed vegetable oil as the renewable energy.In this paper,the mechanism of carbon deposition formation was explored based on the composition and structure of vegetable oil.By studying on the mechanism,a new type of anti-carbon deposition agent has been synthesized,which has favorable effect on the prevention of carbon deposition.It was found that coking phenomenon occurred on the nozzle owing to long-term use of it in the diesel engine.As a result,a high temperature-resistant hydrophobic and oleophobic film was designed and synthesized,and a thin layer of dense film was plated on the nozzle.It can prevent the coking material adhesion,which can protect the diesel engine to start normally,burning smoothly.Through a large number of experiments,the following results have been obtained.(1)By studying the effect of iodine value and average molecular weight on the amount of carbon deposition,it was found that the higher the iodine value and the average molecular weight of the vegetable oil,the more the amount of carbon deposition produced.In the evaporation experiment,it was found that the iodine value(ie,unsatisfaction)of the vegetable oil decreased with the increase of the evaporation time,and the average molecular weight increased with the increase of the time.Therefore,it was tentatively speculated that the reasons for the formation of carbon deposition may be large vegetable oil and the high average molecular weight.The presence of this phenomenon was confirmed by infrared spectroscopy of residual carbon and actual colloids produced by combustion of Jatropha oil.(2)In the study of additives to prevent carbon deposition effect,the best additives are tert-butyl hydroquinone(TBHQ)and polyether amine(PEA).And,a new anticarbon deposition was synthesized by using the linker TDI to connect two additives together.When its added amount reaches 1.2 %,the amount of carbon deposition can be reduced by 31 %.(3)The appearance,thermal analysis and SEM analysis of the carbon deposition produced by the addition of the anti-carbon deposition agent and the addition of the anti-carbon deposition agent were carried out.The results showed that the burning of Jatropha oil was more abundant,and the carbon particles produced by the addition of anti-caking agent were small in size and uniform in distribution,which could slow down the carbon deposition.(4)The hydrophobic oleophobic film was prepared by core-shell emulsion polymerization method.The structure and properties of the emulsion film were tested by infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy and contact angle.The optimum formulation of core-shell emulsion film was determined by the physical quantity test,such as conversion rate,water absorption rate and initial decomposition temperature,as follows: soft and hard monomer butyl acrylate(BA)and methyl methacrylate(MMA)The ratio of emulsifier sodium dodecyl sulfate(SDS)to octylphenol polyoxyethylene ether(OP-10)was 1:1,emulsifier(SDS and OP-10)was 3 %,The amount of initiator ammonium persulfate(APS)is 0.3 %,the amount of trifluoroethyl methacrylate(TFEMA)is 4 %,the amount of Silane coupler G-570 is 10 %.Under the best scheme,the contact angles of the emulsion film to water and oil were 99 o and 94.6o respectively,and the initial decomposition temperature was 408 ?.(5)The method of coating the diesel fuel injection nozzle and the addition of anticoking agent in the compound biodiesel was carried out to control the carbon deposition,and the durability test was carried out on the diesel engine for 100 h.The experimental results showed that the coating and the addition of anti-carbon deposition can significantly slow the formation of carbon deposition on the diesel engine injector,the burning effect and the producing carbon deposition trends are equivalent to 0# diesel's.