This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and...This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.展开更多
The multi-scale characteristics of clusters in a fast fluidized bed and of agglomerates in a fluidized bed of cohesive particles are discussed on the basis of large amounts of experiments. The cluster size and concent...The multi-scale characteristics of clusters in a fast fluidized bed and of agglomerates in a fluidized bed of cohesive particles are discussed on the basis of large amounts of experiments. The cluster size and concentration are dominated by the local voidage of the bed. A cluster consists of many sub-clusters with different sizes and discrete par-ticles, and the sub-cluster size probability density distribution appears as a negative exponential function. The agglom-erates in a fluidized bed of cohesive particles also possess the multi-scale nature. The large agglomerates form a fixed bed at the bottom, the medium agglomerates are fluidized in the middle, and the small agglomerates and discrete parti-cles become the dilute-phase region in the upper part of the bed. The agglomerate size is mainly affected by cohesive forces and gas velocity. The present models for predicting the size of clusters and agglomerates can not tackle the in-trinsic mechanism of the multi-scale aggregation, and a challenging problem for establishing mechanistic model is put forward.展开更多
Particle size distribution(PSD) is an important parameter in the process of fluidization,and it always plays a crucial role in a gas-solid fluidized system.A PSD model for on-line PSD determination based on acoustic e...Particle size distribution(PSD) is an important parameter in the process of fluidization,and it always plays a crucial role in a gas-solid fluidized system.A PSD model for on-line PSD determination based on acoustic emission(AE) measurement was developed according to the mechanism of particle collision with the inner wall of the cylinder and multi-scale wavelet decomposition analysis.This PSD model illuminates the quantitative relationship between the energy percentage of AE signals for different scales and the PSD,which indicates the feasibility of the application of the PSD model.Experiments were undertaken both in lab and plant gas-solid fluidized setup with polyethylene particles,and the parameters of the PSD model were calibrated and revised.The experimental conditions and results proved that the PSD model was suitable for on-line measurement and was sufficiently sensible and accurate.Concerning agglomeration,the PSD model also showed exact serviceability on detecting the onset of agglomeration by abnormal PSD,and the result agreed with that from the radiation method.Ultimately,AE measurement was found to be a reliable and credible means for understanding the PSD information that affects the behavior of a system,which can provide valuable guidance for practical applications.展开更多
基金support and encouragement of the Joint Funds of the National Natural Science Foundation of China(No.U21B2095)the Major Research Project of National Natural Science Foundation of China(No.91834303).
文摘This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.
文摘The multi-scale characteristics of clusters in a fast fluidized bed and of agglomerates in a fluidized bed of cohesive particles are discussed on the basis of large amounts of experiments. The cluster size and concentration are dominated by the local voidage of the bed. A cluster consists of many sub-clusters with different sizes and discrete par-ticles, and the sub-cluster size probability density distribution appears as a negative exponential function. The agglom-erates in a fluidized bed of cohesive particles also possess the multi-scale nature. The large agglomerates form a fixed bed at the bottom, the medium agglomerates are fluidized in the middle, and the small agglomerates and discrete parti-cles become the dilute-phase region in the upper part of the bed. The agglomerate size is mainly affected by cohesive forces and gas velocity. The present models for predicting the size of clusters and agglomerates can not tackle the in-trinsic mechanism of the multi-scale aggregation, and a challenging problem for establishing mechanistic model is put forward.
基金Project supported by the National Natural Science Foundation of China(Nos.21076180and20736011)the National High-Tech R&D Program(863)of China(No.2007AA04Z182)
文摘Particle size distribution(PSD) is an important parameter in the process of fluidization,and it always plays a crucial role in a gas-solid fluidized system.A PSD model for on-line PSD determination based on acoustic emission(AE) measurement was developed according to the mechanism of particle collision with the inner wall of the cylinder and multi-scale wavelet decomposition analysis.This PSD model illuminates the quantitative relationship between the energy percentage of AE signals for different scales and the PSD,which indicates the feasibility of the application of the PSD model.Experiments were undertaken both in lab and plant gas-solid fluidized setup with polyethylene particles,and the parameters of the PSD model were calibrated and revised.The experimental conditions and results proved that the PSD model was suitable for on-line measurement and was sufficiently sensible and accurate.Concerning agglomeration,the PSD model also showed exact serviceability on detecting the onset of agglomeration by abnormal PSD,and the result agreed with that from the radiation method.Ultimately,AE measurement was found to be a reliable and credible means for understanding the PSD information that affects the behavior of a system,which can provide valuable guidance for practical applications.
