Study On The Characterization Of Morphology, Structure And Composition Of Soot Particles From Biomass Fuel

As one of potential diesel engine fuels, the biomass fuel produced by means of biomass pyrolysis technology is usually mixed with diesel fuel and used in engine via emulsion process. The combustion of biomass fuel will inevitably generate soot which will not only be harmful to the environment, but also cause the higher wear of engine cylinder. How to solve these problems has be paid more attention. Based on the understanding morphology, structure and composition of biomass fuel soot, it was investigated to select suitable fuel additive to change the soot properties by way of the variation of fuel components. It will provide some basic data for the development and application of biomass fuel in the diesel engine.(1) The biomass fuel was purified by vaccum distillation process firstly to obtain the refined biomass fuel which would be mixed and emulsified further with different proportions of Owt%,10wt%,20wt% and 30wt% diesel fuel respectively. The above mixed fuels were burnned at ambient temperature and then it was obtained the diesel soot (DS),10wt% biomass fuel soot (BS10),20wt% biomass fuel soot (BS20) and 30wt% biomass fuel soot (BS30), respectively. It was found that all of soot particles were of spherical structureand also formed agglomerates like chain by way of linking between the particles. The primary soot particle of BS20 showed the smallest diameter of about 32nm, the average diameters of the primary particles of other soots were about 38nm. In addition, the BS30 soot was of highest degree of graphitization. There were the highest contents of C=O and C-O-C groups on the BS20 soot surface, which might be attributed to the varying oxidation degrees of complex components in the biomass fuel.(2) It was prepared the emulsified fuel consisiting 95wt% diesel and 5wt% refined biomass fuel using the same emulsion process mentioned above and used in S195 model diesel engine. The diesel engine was operated 10 hours without load. The different soot particles were collected inside the sump as BSS and the exhaust pipe as BSE respectively. At the same time, the soot particles BS5 was also collected when the present emulsified biomass fuel was burned at room temperature. It was found that their primary soot particles were also of spherical structure and shown a chain of agglomerates between the particles linked each other. However, there were some impruities in the soot particles BSS and BSE. The average diameter of primary particles of BSS was about 29nm, BS5 38nm and BSE 52nm. The graphitization degree, the type and quantity of surface oxygen functional groups of BS5 were higher than those of BSS and BSE. On the other hand, the content of surface functional group containing oxygen of BSS was higher than that of BSE. Their morphology, structure and composition of BSS, BSS and BSE were similarin which their main difference were came from the respective impurities in the soot particles.(3) Onefuel additive "Hai Long" was selected and added in the emulsified fuel with 5wt% biomass fuel, and the soot particles were collected as combustion in air at room temperature. Two kinds of soot particles BS5 and BS5A were compared under two kinds of conditions of before and after addition of "Hai Long" fuel additive. It was found that BS5A soot and BS5 soot had same morphology (spherical particles were agglomerated with bead-chain structure); and the graphitization degree of BS5A was higher than that of BS5. It was also found the lower contents of C-OH and C-O-C groups and the higher content of C=O functional group in BS5A soot which might be resulted from the additive influence on the oxidation of soot.