Experimental Study On Product Characteristics Of Bamboo Pyrolysis Based On Pyrolytic Polygeneration

As a kind of biomass resources, bamboo have a huge potential to provide clean energyand bamboo charcoal materials. Compared with normal pyrolysis, polygenerationtechnology is an important development direction while it can provide higherenergy-conversion efficiency and economic profitability. This thesis takes typical biomasssample, bamboo pieces, to investigate the characteristics of the products and the mechanismof pyrolysis, to provid a significant basis for the design of polygeneration system.In order to study characteristics of biomass pyrolysis process, the heating rate and fourkind of typical biomass samples were investigated in thermogravimetric (TG) analysis. Theresult shows that the composition and material characteristic has a significant influence ofbiomass pyrolysis. With the heating rate increasing, the TG curve moved towards highertemperature, and the range of pyrolysis temperature becomes wider. With the increase ofthe conversion, activation energy of bamboo pyrolysis became higher first, and then wentdown again.Bamboo pyrolysis experiments were carried out in the fixed bed reactor, products wereanalyzed respectively by using different methods. With the temperature increasing, thesolid char yield decreased obviously, while the biogas yield rising, the liquid oil yielddidn’t changed much. Cellulose and hemicelluloses were decomposed at low temperature,CO and CO2were released. After the temperature rose over450℃, lignin began todecompose, and the content of H2and CH4rose sharply. Liquid oil is mainly consists ofacetic acid, furfural, ketone and phenol. With the lignin decomposed in high temperature,phenol class materials increased quickly, indene and naphthalene appeared at thetemperature after650℃. Various pores were found in bamboo char, the percent ofmicropores increased while the temperature increasing, but when decreased at hightemperature, SBETof mesopores changed little. SBETand fractal dimension of bamboo char got the highest value at the temperature650℃.The pilot-scale experiment of bamboo pyrolysis was taken on the moving bedpyrolytic polygeneration system, the result showed the calorific value of the gas productachieved12MJ/m3, and the bamboo charcoal’s calorific value reached28MJ/kg. Liquidproduct mainly contains light components; heavy components were hunted by fillers in themoving bed. The experiment indicated the moving bed pyrolytic polygeneration systemcould operate stably and improved the energy utilization efficiency remarkably.Characteristics of bamboo char combustion was analyzed on TGA, the result showedthe first combustion peak moved to higher temperature and merged with the second peakwhile the preparation temperature increasing. The biggest peak appeared at the charprepared at550℃, and became smaller gradually after650℃. The general combustionindex S was small when the preparation temperature too low or too high, char prepared at650℃had the best combustion characteristics. The atmosphere of CO2was not good forthe first step of bamboo char’s gasification, and the gasification process was very complex.With the increasing of preparation temperature, the reactivity of bamboo char with CO2increased first, and then decreased, that indicated the characteristic of pore structureoccupied the central position of bamboo char’s gasification.