Research On Microalgae Pyrolysis Mechanism And Process Condition

To research the general pyrolysis characteristics of microalgae biomass, In this paper the pyrolysis characteristics of several microalgaes and mimetic compound of oil-algae was studied by using thermogravimetric analysis and other technical analysis tools.The pyrolysis characteristics of three main components of microalgae were studied using three model compounds as their alternate. Chlorella and oil-algae were selected as the study sample and their mechanism、pyrolysis kinetics and the impact of content were studied. The influence of experimental conditions on pyrolysis reaction was studied in tube furnace reactor based on previous research、the bio-oil components were analyzed by using GC-MS、the sample and carbon residue were studied by using FTIR.The results shows that:1.Microalgae biomass contains large amounts of volatile,the pyrolysis process can be divided into drying dehydration, severe weight loss, slow charring three stages.The initial volatile temperature of microalgae is lower than the woody biomass due to the different main components of two kinds of biomass.The pyrolysis characteristics of oil-algae and Chlorella are outstanding among the four materials.The pyrolysis temperature corresponding to the maximum weight loss rate of oil-algae is than normal microalgae, pyrolysis reaction mechanism function in main reaction stage of the four materials can be described by a second-order reaction model.2.Take protein powder、peanut oil、starch as the alternates of the main components in the microalgae to do the research.Three components have similar pyrolysis process,all can be divided into dehydration, rapid weight loss, slow weight loss three stages;Pyrolysis parameters are very different,Pyrolysis rate peak temperature of protein and starch is around 300℃ while the peanut oil is around 400℃3.The pyrolysis process of Chlorella and oil-algae both can be divided into three main stages and there is no significant difference in the range divition based on temperature.But the residual amount and pyrolysis parameters (weight loss rate peak Dmax, weight loss corresponds to the peak temperature Tmax, pyrolysis product release index r, etc.) are very different;Component content and heating rate has a great influence on the pyrolysis behavior of biomass.The maximum weight loss rate of the oil-algae and it’s corresponding pyrolysis temperature are higher than the chlorella’s, The pyrolysis processes of Chlorella and oil-algae are moving to the high temperature zone with the heating rate increases;TGA-FTIR technique results showed that the pyrolysis product of both biomass are complex,the pyrolysis process match the TG-DTG curve change,The kinetic parameters were calculated by two methods:FWO and KAS,the best mechanism function were calculated by using the mature multiple scanning method,the results shows that:The activation energy of two biomass getting bigger as the reaction getting deeper,In the main reaction stage, can be used to describe chlorella pyrolysis process while can be used to describe oil-algae pyrolysis process.4.The main reaction interval of each the of three main components is soybean protein 200-500’C, starch 280-400℃、peanut oil 330-480℃.The overall pyrolysis process of all three components move to the high temperature zone as heating rate increase,The maximum precipitation rate increases rapidly with increasing heating rate;The thermal stability order of them is peanut oil> starch> soy protein based on the comparation of their activation energy.Popescu method was used to calculate the respective pyrolysis mechanism function,soy protein is , starch ispeanut oil is. The effects of temperature and time on Chlorella and oil-algae was tested in laboratory and the optimum temperature and the best time to make maximum bio-oil yield exsit in both biomass pyrolysis process,the results show taht:A wide range of similar components in these two kinds of oils, but the oil derivatives in oil-algae oil are more than these in chlorella oil which corresponds to the major component content in two kinds of biomass;The Infrared analysis results of biomass and carbon residue showed that two kinds of biomass contains roughly same kinds but different quantity of components,the pyrolysis reaction went more complete under the selected experimental conditions.