Study On Pyrolysis Characteristics And Kinetic Of Biomass(Seaweed)

Biomass is a kind of renewable resource and it is of significance to transform it into high-quality energy.Because pyrolysis of biomass is an important thermal-chemical conversion technology.Study on biomass pyrolysis kinetics can provide some theoretical foundation for thermalchemical conversion of biomass.The pyrolysis characteristics of the seaweed samples were investigated by TA analyzer and the pyrolysis kinetics were also studied.Finally,the microwave pyrolysis of seaweeds was carded out,and the gas and liquid products were analyzed by GC and GC-MS respectively.The conclusions are as following:The pyrolysis characteristics of six seaweeds were investigated applying thermogravimetric analysis technique.The pyrolysis experiments were performed up to 700℃at heating rates of 10,20,30,50 and 80℃/min in a dynamic nitrogen flow of 100 mL/min.Despite pyrolysis peaks of six seaweeds were difference,three stages (dehydration,main devolatilizations and residual decomposition)appeared in the pyrolysis process.Furthermore,experiments with blends of Gracilara and fir were conducted at different proportion(1:2,1:1 and 2:1)under the same conditions at a heating rate of 10℃/min.The results showed that blends could realize Energy coupling.The influences of ash,particle sizes and heating rate on the process of seaweeds pyrolysis were inverstigated.Seaweeds were acid-washed and water-washed respectively.Acid-washing affected not only peak height of DTG curves but also peak shape;Water-washing had a small influence on DTG curves,because acid can destroy chemistry structure,which can make samples more reactive.No obvious influence of the particle size was detected on devolatilization characteristics,but when the particle size is less than 0.20mm,the coke were slightly increased;Experiments showed that TG and DTG curves all moved to higher temperature ranges with increasing heating rate.According to TG data,activation energies for pyrolysis of six seaweeds and Gracilara at different particle sizes were calculated by FWO and Popescu methods respectively.Mechanism functions were ascertained at different temperature range by Popescu method,The results showed that mechanism functions of six seaweeds were different,but that of Gracilara at different particle sizes only switched between [-ln(1-α)]⁴ and[-ln(1-α)]³.No significant influence of the particle size was detected on the kinetics.The results indicated that the activation energies calculated by the two different methods are approximately identical.The results of microwave pyrolysis showed that gas products were mainly consists of H₂,CO,CH₄,CO₂ and liquefaction products contained mainly acid,ketone,water, aldehyde and nitride et al,according to analysis by gas chromatography(GC)and gas chromatography- mass spectrum(GC-MS)respectively.Figure 40 table 17 reference103...