Study On Coupling Mechanism Of Co-pyrolysis Of Seaweed Biomass And Rice Husk

Energy is the material foundation for human society to survive and develop,however,energy shortage and environmental pollution are becoming more and more serious,they have become major problems affecting the development our society,so the development of renewable clean energy is imminent.As a new type of renewable energy,biomass energy has great potential for development,it has caused attention all over the world,including the Netherlands and many other countries.In addition,these countries have been conducting extensive research on biomass and have formed biomass energy development system with national characteristics.As a large agricultural country,China has a long coastline.There is plenty of biomass,not only common wood,crops and other terrestrial biomass,but also the marine algae biomass.Algae biomass has the advantage of not taking up arable land and short growth period.What's more,algae will absorb carbon.And the carbon will go back to the atmosphere again after the death decay to ensure the relatively short period of time "carbon neutral".So algae is the real clean energy withour producing extra greenhouse gas.In addition,seaweed biomass has strong photosynthesis ability,so they can absorb a lot of greenhouse gases effectively.In addition,the algae can also contribute to the restoration of the marine environment,so algae biomass has tremendous development potential.Some scholars at home and abroad have begun to study algae biomass.Now,the co-pyrolysis research of algae biomass and terrestrial biomass is still rare,which is a new issue.In this paper,the co-pyrolysis process of the algae biomass and the terrestrial biomass rice husk was systematically tested and explored.The main contents and results are as follows:1.The thermogravimetric analysis was used to analyze the process of pyrolysis and co-pyrolysis.The results showed that the initial pyrolysis temperature of enteromorpha clathrata was lower,while the maximum heat loss rate of rice husk was higher.And in the main stage of pyrolysis,the enteromorpha clathrata was exothermic,and the rice husk was endothermic,and the main pyrolysis stage after the mixture was also exothermic.Therefore,the co-pyrolysis of the enteromorpha clathrata and rice husk achieves the coupling of energy and there is the possibility of synergies.2.The process of pyrolysis of enteromorpha clathrata,rice husk and their mixture were studied by bench test.The effects of mixed pyrolysis on the yield of three-phase products,bio-oil and pyrolysis gas were discussed.The results show that the yield of gaseous products after mixed pyrolysis is higher than the theoretical value,indicating that co-pyrolysis has a promoting effect on the formation of gas-phase products.At the same time,the small molecular hydrocarbons,mainly methane,ethane,ethylene and propane,were higher than the theoretical value,and the small molecular product represented by acetic acid in the bio-oil was significantly increased.The synergistic effect of the co-pyrolysis of the enteromorpha clathrata and the rice husk was further verified by the catalytic effect of alkali metal such as Na and K in the ash of the enteromorpha clathrata.3.The effect of volatiles on the semi-coke was studied.The results showed thatthe interaction of rice husk volatiles to semi-coke of enteromorpha clathrata was mainly manifested in free radicals of rice husk induce half-coke of enteromorpha clathrata condensation and aromatization reactions.So that the carbon structure in the semi-coke is transformed into the aromatic structure.The interaction between the volatiles of enteromorpha clathrata on semi-coke of the rice husk is mainly manifested in volatile phase and semi-coke in the unstable and high activity point polycondensation reaction,making the aromatic structure to the greater degree of condensation of the development of large ring,so that the structure of the smaller proportion of aromatic ring decreased.4.Two major polysaccharide molecules(sulfuric acid polysaccharide and fucoidan)in seaweed and the main components of rice husk were selected as the research object.The molecular dynamics simulation of seaweed polysaccharide and cellulose model compounds was carried out by molecular simulation software ADF,and the Amber force field and Reax FF force field were simulated by molecular dynamics simulation.The results showed that there were many similarities in the pyrolysis characteristics of seaweed polysaccharides,but they had different thermodynamic characteristics during the pyrolysis process because of the differences in molecular structure.One of the most obvious is that the two pyrolysis temperature range does not completely overlap,polysaccharide molecules in advance pyrolysis produce a lot of hydrogen to the cellulose,so that the cellulose pyrolysis more fully.The simulation results of the co-pyrolysis are compared with the simulation results of the individual pyrolysis superposition.It indicated that the co-pyrolysis can promote the pyrolysis of the two materials,increase the pyrolysis conversion rate and the gas production rate in the middle temperature range.