Experimental Analytic Method For Biomass Tar And Bio-oil

Biomass with very specific properties, such as versatility and steady energy storage, can be considered as one of the promising environment friendly renewable energy. To convert the biomass energy thermally by gasification and pyrolysis is regarded as two significant technologies. However, the tar and bio-oils which are some unwelcome properties such as high water, oxygen content and corrosive, unstable at heating, limited the popular application of gasificaton and pyrolysis.This thesis summarized the research results and ubiquitous problems of the biomass gasification and pyrolysis in domestic and overseas foreign researchers. The common problem is lack of uniform and systemic analytic methods of tar and bio-properties. Based on consulting a lot of the analytic methods on tar and bio-oil, two suits of analytic protocols were designed. One is used to determine the tar contents and identify the main compounds and the other is to examine physicochemical properties of bio-oils.The tar sampling was conducted with cold trape in dichloromethane and the tar content in product gas was determined by gravimetric analysis, this process was calculated from evaporation residue of tars in a heating chamber at 105°C for one hour.Five parallel analysis was made for the same tar sample .The data of tar contents were obtained. The relative standard deviation of these data was 0.9869%, this gravimetric analysis method with high accuracy and repeatability was assessed. The tar contents in different gasification conditions were also determined by this method.In order to assess the quantitative analysis by GC/FID and qualitative analysis by GC-MS, a standard compound solution was prepared and was analysed by the GC/FID , the results of each component concentration and its retention time were obtained by Using GC-MS Standard mixture: 3μL/ml styrene,2μg/ml phenol,3μg/ml 4-methylphenol,3μg/ml Naphthalene,2μg/ml anthracene and 3μg/ml phenanthrene.Thrice parallel determinations for this standard sample were performed by GC. the relative standard deviation of these analytical data were computed and the results were as follows: 0.987%,1.716%,1.509%,1.318% 0.901% and 4.860%. the relative errors between the value and the average were: 1.68%,1.24%,1.44%,1.54%,1.2% and 0.52% . From these data, it showed that this quantitative analysis method is exact and repeatabilityThe retention time data of each component were gained by GC analysis. Deviation between the average and the retention time of the same compound by GC-MS is less than 0.05, it shows that GC-MS is suitable for qualitative analysis.The main volatile components from biomass-based tar in different gasified conditions were identified by GC-MS and theirs relative contents were determined by GC/FID. The experimental data indicated that the tar concentration primarily depends on the operating temperature and the analytic method in applying range was gained.Physical properties of bio-oil from biomass pyrolysis were analyzed with the modern apparatus and suitable methods .There included :water content,pH,solids content,heat value and elemental analysis.Many qualitative approaches of the components in different bio-oils were reviewed in this thesis and an advanced method which is GC-MS analysis was adopted. In order to assess the analytical method in reliability and accuracy, the standard sample and the bio-oil + standard sample mixture had been analysed by GC-MS and GC/FID before different bio-oil samples were tested.The model compound solution was prepared with 4.8μl/ml acetic acid,methyl acetate,pyridine and furfural, 5μg/ml phenol,pyrocatechol,resorcin. The deviation of each compound retention time in bio-oil sample by GC-MS analysis is under 0.074.The result indicated that the complex sample qualitative by GC-MS analytic method is reliable.The main volatile components from bio-oil in different pyrolysis conditions and biomass materials were identified by GC-MS and the relative contents were determined by GC/FID. According to basic components and the relative content, the characters of bio-oil with high oxygen content and high water content were explained. The influences of pyrolysis parameters for bio-oil properties and theirs relative contents ware contrasted.