Detection And Analysis Of Particle Coking In Gas-Solid Fluidized Bed

In recent years,gas-solid fluidized beds have been widely used in various industries,such as the pharmaceutical industry in the chemical industry,blast furnace ironmaking in the metallurgical industry,coal combustion in the power industry,and continuous use in biomass fluidized beds.The high-adhesive solid particles in the furnace are out of flow,causing the particles to unite and cause bad working phenomena such as dead beds,thus affecting the normal operation of the fluidized bed.In order to solve the problem of particle bond loss,this paper introduces multiple signals in a cold bubbling fluidized bed to detect and analyze the different fluidization states,especially the coking state,to obtain the particle bond flow loss.Regular characteristics.Around this goal,three research work has been carried out:(1)experimental study on attenuation of ultrasonic signals in fluidized bed;(2)experimental study on correlation of signals(such as hood pressure signals)in bubbling fluidized beds;3)Research and analysis of the phenomenon of particle bonding loss in fluidized bed by means of ultrasonic,pressure and acoustic emission.The following results have been achieved:(1)The law of ultrasonic attenuation of particles in a fluidized bed is obtained.When the bed materials are quartz sand and sawdust respectively,the ultrasonic wave is filtered to control the rated air volume,and the probe position is changed.Finally,when the air volume is constant,the particle size is larger,and the attenuation degree is also larger.When the working condition is the same probe position of the same kind of particle,the air volume is changed,and finally,when the volume fraction of the particle is decreased,the attenuation degree is also reduced.It is known from this experiment that the biomass particles still conform to the ultrasonic attenuation law in the gas-solid two-phase flow,and provide some experimental data and theoretical basis for the ultrasonic sensor to analyze the flow state of the biomass particles in the fluidized bed..(2)The law between the pressure signals of the hood in the fluidized bed is obtained.According to the time domain diagram and the box diagram,the difference in bed material also affects the hood pressure signal.The principal component analysis can be used to analyze the experimental data.Under different working conditions,the main axis is diffused and distributed on the principal component.Each projection point has a certain interval,which does not intersect with each other and does not cross with the increase of air volume..This shows that the pressure signals of each hood represent the state of the respective zones and are irrelevant to each other.Through the distribution of the hood pressure signal mean value with the air volume change,it is known that it is feasible to study the fluid pressure state in the fluidized bed by using the wind pressure independence to analyze the pressure fluctuation signal of the hood at different positions.The pressure fluctuation signals of the hood can be reflected at different positions.The law of operation in the bed changes.(3)Using a variety of technical means to simultaneously measure the flow signal in the fluidized bed,the analysis of the phenomenon of particle bond loss in the fluidized bed is realized.By analyzing the ultrasonic signal data,in the time domain diagram,the signal energy of the fluidized bed in the coking state slightly increases.In the box diagram,the fluctuation range of the normal value of the fluidized bed ultrasonic signal becomes larger when coking is performed.It is obtained from the variation of the amplitude with the wind volume.The different working conditions are accompanied by the increase of the air volume,and the ratio of the signal amplitude decreases when the coking occurs.It can be seen from the hood pressure fluctuation signal that,as seen from the time domain diagram,when the air volume increases under different working conditions,the energy fluctuation of the hood pressure signal at different positions remains basically unchanged,but the vent pressure fluctuation position changes.It can be seen from the box diagram that the normal value range of coking is only the pressure of the hood at the 5th.Obtained from the principal component analysis chart,the hoods are not related to each other.In the normal pressure state of the fluidized bed,the average pressure of the fluidized bed increases with the air volume.When the coking state is reached,the average hood pressure at different positions becomes larger.The average pressure of the hoods No.3 and No.5 is disordered..It can be obtained from the acoustic emission signal.It can be seen from the time domain diagram that as the air volume increases,the amplitude of the signal of the position sensor increases little,and the amplitude of the sensor No.3 changes significantly during the coking.It can be seen from the box diagram that in the coking state of the fluidized bed,the normal value range of the sensor signals of No.2 and No.3 is larger than the normal value of the normal fluidization of the fluidized bed,and the normal value of the sensor signal of the remaining position is decreased.According to the principal component analysis chart,the signals collected by the sensors at different positions are still independent.It can be seen from the change of the signal amplitude with the wind volume that the amplitude of the amplitude signal of the sensor at different positions decreases when the fluidized bed is cokeed.