Study On Gasification Characteristics Of Pine And Bamboo Char With CO₂

With the fossil fuel resource over-consumed and the serious environmentalpollution caused, the biomass energy as the fourth energy attracts more and moreattention. The thermo-chemical conversion, which can produce higher caloric valuesynthesis gas and realize the use of renewable resources, is considered to be of greatestresearch and development potentiality.In this study, on the basis of in-depth analysis of the status for biomass chargasification research, the influence of different reaction conditions （different catalysts,gasification temperature and CO₂flow） on the gasification of biomass char （pine,bamboo） were investigated using thermal gravimetric analysis （TGA）. And threedifferent kinetic models were employed to obtain gasification kinetic parameters forbiomass char by the method of Doyle. In addition, the biomass char gasificationexperiments with different temperature, particle sizes and different catalysts werecarried on a self-made fixed gasification reactor. A gas chromatograph was used toanalysis gas composition, and then we calculated the calorific value and carbonconversion. The catalytic mechanism and the different periods of char samples wererespectively studied by using thermo-gravimetric analyzer and scanning electronmicroscope （SEM）.The experimental results indicated that: the conversion rates of biomass char （pine,bamboo） increase with the reaction temperature and the average gasification rateincrease with increasing CO₂flow. When the temperature is under950℃, the effect ofcatalytic gasification with impregnation method is better than with direct mixingmethod. And compared with non-catalytic gasification of biomass char, the addition oftransition metal could significantly improve the conversion rate of pine char gasificationcompared with bamboo char gasification. It is found that the activation energies of twobiomass char are reduced by adding transition metal. There exist certain kineticcompensation between activation energy and pre-exponential factors.The temperature and particle sizes have major impact on char gasification withCO₂from gas production characteristics. CO₂reduction reaction was promoted and COin synthesis gas increases by the increasing of gasification temperature. But with thedecrease of particle sizes, CO yield first increased and then decreased. The addition ofNi and Fe could significantly improve the yield of CO for two char gasification, and the optimum addition quantity is about10%.The results also indicate that the addition of Fe₂O₃and Fe have no great differenceon pyrolysis, but could significantly improve the gasification of pine char and bamboochar. And the catalytic effect of adding Fe₂O₃is better than Fe for char gasification.Comparing different period images of samples, it can be found that pine char has morepore structures than pine, and the white "spot" are observed on the surface of sample byadding Fe₂O₃, which confirm that Fe₂O₃plays a catalytic role on the char gasification.