Process Study On Biomass Pyrolysis Under Flue Gas Atmosphere

As the society develops,The increasing amounts of MSW have brought great trouble to the development of the cities in China.Compared with the traditional MSW disposing technology,pyrolysis technology has considered being a better technology for MSW treatment in the terms of reducing the weight and volume of MSW.It has a bright development prospect.Based on the preliminary study,a new MSW treatment concept called loop process of pyrolysis under flue gas atmosphere combined with combustion of low calorific value gas has been proposed in this paper.Firstly,in order to investigate the effect of MSW particle size,temperature increasing rate and reaction environment on the process of pyrolysis,a combined TG-FTIR technique was conducted and kinetic parameters,such as activation energy and pre-exponential factor,were estimated through thermal dynamics analysis.The experimental results indicate that gas quality produced under the flue gas reaction environment is better than the nitrogen atmosphere.Compared with small particle size(0.1mm),lager particle size(0.9mm)is helpful to enhance the effect of pyrolysis.With the increasing of the heating rate,the reaction time is shorter and reactions are more fully.Secondly,the pyrolysis experiment in the tube furnace was carried out and it results that the intensity of product gas is bigger under the flue gas reaction environment when the diameter of the particle is 0.9mm.Higher pyrolysis temperature contributes to reduce the content of fixed carbon in the residue.It is also shown that a longer gas phase retention time favors the the secondary cracking reactions and improves the quality of the pyrolysis gas.After that,continuous pyrolysis experiment was conducted and the influences of the biomass to flue gas ratio on the pyrolysis were obtained from the experiment result.According to the results of comparative experiments,the LHV value of pyrolysis gas is higher under oxygen-rich condition and the growth trend of LHW value slows down with the increase of oxygen percentage.The LHW value is up to 3.95 MJ/m3 under a condition of methane flow rate of 3 l/min,oxygen flow rate of 3.67l/min,air flow rate of 16.67l/min and feed rate of 0.013kg/min.Finally,A model for fixed-bed pyrolysis of biomass was developed using Aspen plus and effects of oxygen-rich proportion and oxygen content of the flue gas on the pyrolysis process were simulated.The trend of simulation values is consistent with the experimental result.The results of the research in this paper provide technical data and theoretical support for the implementation of the loop device.