Study On Chemical Chain Gasification Characteristics Of Wood Waste Based On NiO Modified Oxygen Carrier

With the development of domestic economy and population growth,the demand for wood-based panels increases year by year.The manufacturing process of wood-based panels will inevitably produce a lot of waste materials.Additionally,the service life of wood-based panels is short,the accumulation of discarded wood-based panels increases the cost of conventional disposal.Based on the principle of efficient resource utilization and low cost treatment of wood waste,Chemical looping gasification technology（CLG）was used for treatment.In this paper,hematite loaded with NiO is used as oxygen carrier to achieve efficient resource utilization of wood waste,which has the advantage of improving the reactivity of hematite and reducing the amount of oxygen carrier in the process of chemical looping gasification,and provide a new choice for the selection of oxygen carrier.In this context,this paper systematically studied the chemical looping gasification characteristics of NiO modified hematite with wood waste,and the evolution of oxygen carrier during cycle.First,we synthesized four modified oxygen carriers with different NiO loads by high temperature calcination,analyzed the elemental composition and crystal phase structure by XRF and XRD.The effect of NiO modification on oxygen carrier was investigated on a thermogravimeter.Additionally,the reaction performance of different oxygen sources（Al₂O₃,Fe₂O₃and NiO modified oxygen carrier）with wood waste was investigated based on the fixed bed.The results showed that a new phase Ni Fe₂O₄is generated on the modified iron ore,the foreign metal Ni was successfully loaded onto hematite by high temperature calcination.The oxygen content of the modified oxygen carrier increases with the increase of NiO loading capacity.In the thermogravimetric reaction of each oxygen carrier with wood waste in H₂atmosphere and inert atmosphere,the increase of NiO load increases the lattice oxygen of oxygen carrier,reduction performance and conversion capacity of wood waste.The carbon conversion rate,valid gas yield and cumulative valid gas production of wood waste increased from 54%,0.55m³/kg,293.96ml and 68%,0.588m³/kg and 351.68ml when oxygen carriers were Al₂O₃and Fe₂O₃,to 78%,0.69m³/kg and 445.82 ml when oxygen carriers were Ni10.The modified oxygen carrier has the best char conversion ability because of its high activity and oxygen load.The process of chemical looping gasification of wood waste and its model compounds was qualitatively analyzed by TG and TG-FTIR.The results show that the modified oxygen carrier can provide active lattice oxygen for the reaction system in thermogravimetric experiment.Lattice oxygen provides oxygen source for pyrolysis intermediates and residual char of lignocellulosic waste and its model compounds.It is beneficial to the conversion of wood waste and tar,thus increasing the weight loss rate of wood waste.At the same time,in the infrared spectrum,the modified oxygen carrier significantly promoted the generation of carbon oxides,that is,more carbon elements in the wood waste were converted into gaseous products.The effects of NiO-modified oxygen carriers and lignin waste gasification under different conditions were systematically studied on a fixed bed,and the evolution of oxygen carrier during cycle were characterized.The results show that too high or too low O/B（oxygen carrier/biomass mass）is not conducive to the production of high quality syngas,and the optimal O/B value is 1.The increase of reaction temperature is beneficial to the conversion of wood waste,and the growth rate of carbon conversion tends to be gentle after850℃.The introduction of appropriate water vapor content is beneficial to the conversion of wood waste and the improvement of syngas quality.Too high water vapor concentration will reduce the reactor space temperature distribution and the average residence time of gas,and the optimal water vapor concentration is 40%.With the increase of the number of cycles,the ash accumulated in the cycle process leads to a slight increase in carbon conversion rate.The pore structure of regenerated oxygen carrier is enlarged,and the structure of oxygen atom and crystal phase is almost the same as that of fresh oxygen carrier.