Study On Pyrolysis Characteristics Of Salix Psammophila And Coaland Synergistic Mechanism Of Co-pyrolysis

Salix psammophila,which has the characteristics of immediate growth after cutting,is rich in hydrogen and can compensate for the hydrogen-poor characteristics of coal.Co-pyrolysis of coal and salix psammophila will increase the conversion rate of coal,increase raw material utilization,and reduce resource waste.This experiment analyzed pyrolysis of salix psammophila and coal and co-pyrolysis of different blending ratio of salix psammophila and coalunder different atmosphere by using temperature programmed thermogravimetric analysis and a pyrolysis reactor.The individual pyrolysis characteristics of the coal and the interaction effcet between the two when adding different salix psammophila blend ratios were studied.Using an temperature programmed thermogravimetric analysisto analyze the individual pyrolysis experiments of coal and salix psammophila under different N₂/CO₂ atmospheres,which found that coal and salix psammophila have some interaction.The absolute value of the coal weight loss rate under an oxygen-free atmosphere has a value larger than the absolute value of the weight loss rate of salix psammophila.In addition,the absolute value of the first weight loss rate of salix is greater than that of coal.This experiment analyzed different blending ratio of salix psammophila and coalunder different CO₂/N₂ atmosphere by using temperature programmed thermogravimetric analysis.Pyrolysis kinetic parameters were obtained after the experiment,and the interaction between salix psammophila and coal were studied.The experimental results show that the two main pyrolysis temperature sections overlap each other,and the interaction rate is not equal to 0,which proved that coal and salix psammophila have some interaction.When CO₂/N₂=5:5,the coal and salix psammophila at the high temperature pyrolysis of different blends of coal and salix psammophila mixtures had promoting effect?mixture with 20%salix psammophila content>80%mixture with salix psammophila content>50%mixture with salix psammophila content?.When coal:salix psammophila=5:5,the larger the proportion of CO₂ atmosphere under different atmosphere proportion at high temperature pyrolysis,the stronger the interaction between salix psammophila and coal. Application of Coats-Redfern method to analyze the pyrolysis kinetics show that the activation energy of the range between 15⁷0 kJ·mol^-1,and the activation energy of salix psammophila was higher than that of coal.The activation energy required for the high temperature section is greater than for the low temperature section.Both the CO₂/N₂ atmosphere ratio and the salix psammophila/coal ratio have a certain influence on the activation energy and pre-exponential factors.And this experiment analyzed different blending ratio of salix psammophila and coal under different O₂/CO₂atmosphere by using temperature programmed thermogravimetric analysis.The result showed that the combustion characteristic of the sample have some regularities along with the change of oxygen concentration and its mixing ratio.The combustion mechanism of samples with oxygen content?50%were multiphase combustion.The combustion mechanism of samples with oxygen content?20%were homogeneous combustion.A mixture of salix psammophila and coal had varying degrees of mutual coordination/inhibitionwithin the range of different pyrolysis of interval.And the biggest coordination were mixture of salix psammophila content about twenty percent and O₂:CO₂=4:1 atmosphere.The biggest inhibition were mixture of salix psammophila content about twenty percent and pure O₂ atmosphere.The co-pyrolysis of salix psammophila and coal was conducted in a pyrolysis reactor.The interaction between coal and salix psammophila at different ratios was investigated.It was found that the promotion and inhibition effects of the co-pyrolysis experiment were more obvious at 20 wt.%and 40 wt.%salix psammophila,respectively,indicating a certain synergistic effect.The results of the N₂adsorption-desorption experiment showed that the addition of salix psammophila increased the surface area and decreased the pore size of the co-pyrolysis char.The Fourier transform infrared?FT-IR?spectra indicated that the pyrolysis tar contained mainly aromatic rings and fatty compounds.The addition of salix psammophila was beneficialtothe decompositionof phenolichydroxyls,etherbonds,and oxygen-containing heterocyclic rings in the coal tar.However,the addition of 50 wt.%salix psammophila blocked the pores of the coal and thus obstructed its pyrolysis,while the porosity of the co-pyrolysis char became more abundant.Richer porosity of the char implies great potential to be widely used in the sewage treatmentindustry.