Study On The Maximum Liquid Intake Of Inert Particle Fluidized Bed Drying

Inert particle fluidized bed drying fluidizes the material with inert particles through drying medium,comparing with fluidized bed drying,it increases the contact surface and heat transfer coefficient,for better drying effect.In addition to the materials that can be dried in ordinary fluidized bed,it is also suitable for high humidity viscosity and heat sensitive materials.As a drying technology with advantages of large heat transfer coefficient,easy operation,perfect economics and so on,it has been used in many fields such as chemical industry medicine and food.Although inert particle fluidized bed drying has certain development time and maturity,fluidized states are not always stable during fluidized drying because of various influence factors.With the continuous addition of materials,the feed amount of the material exceeds the drying limit of the fluidized bed,the new material is coated again when the material wrapped on the inert particles is not completely dried and does not fall off from the inert particles.Covered the incompletely dried coating,forming a liquid bridge force between particles,resulting in particle-to particle bonding,coalescence,and sometimes even blocking the holes of the gas distribution plate,reducing fluidizing gas velocity leads to deterioration of fluidizing quality.In order to solve these problems,a method of temporarily increasing the temperature and gas velocity are often used to improve the fluidization quality in industrial operations,but this method may bring about a series of problems such as increased energy consumption or bed collapse,so we need to fully understand the maximum liquid intake of the equipment under certain operating conditions before operation,Determine the effective liquid intake before the experimental operation,so as to effectively reduce or even prevent the occurrence of coalescence and adhesion.In order to solve the problem of coalescence of inert particle fluidized bed drying technology in industrial production,on the basis of understanding the coalescence mechanism and detection and analysis method,this paper takes glucose solution as theresearch object,through the inert particle fluidized bed in the process of fluidization The pre-experiment for the detection and analysis of temperature,humidity and pressure has obtained whether the current feed volume is the maximum feed volume in the way of detecting and analyzing the smoothness of the standard deviation of the pressure difference fluctuation within 10 hours of fluidized drying time The evaluation standard is that the unit of the maximum liquid volume is L/(h·kg inert particles),which is used as the unit so that the model built is suitable for the study of different inert particle fluidized beds.Based on this,studying on the maximum liquid feed of inert particle fluidized bed under different fluidized gas velocity,inert particle diameter,hot air temperature and material viscosity.Experimental studies have found that the standard deviation of pressure fluctuations tends to fluctuate relatively smoothly first,and then gradually rises.At an inlet speed that does not exceed the maximum liquid intake,the standard deviation of pressure fluctuations will eventually tend to be relatively stable,while exceeding the maximum liquid intake,at this time,the standard deviation of pressure fluctuations will eventually show a significant downward trend.The Fourier transform is used to convert the pressure fluctuation time-domain signal into a frequency-domain signal,Frequency domain analysis of the pressure fluctuation frequency spectrum at different periods under the maximum liquid intake and the feed condition of more than three times the maximum liquid intake,the study found that the pressure fluctuation frequency spectrum can better reflect the fluidized quality of the fluidized bed of inert particles.The frequency fluctuation and the peak power density are closely related to the fluidized mass of the inert particle fluidized bed.In the paper,after analyzing the effects of different operating conditions on the maximum liquid intake,the data obtained from the experiment is dimensionally analyzed.Taking the viscosity of the material as the basic dimension,the correlation formula of the maximum liquid intake of the inert particle fluidized bed is established,and the data is substituted into the model to obtain the maximum liquid intake.Comparing the calculated value of the maximum liquid intake model with the experimental value,the error is within ±15%,the agreement is good.The determination of the criteria for determining the maximum intake of inert particle fluidized bed drying,the study of pressure fluctuations,and the establishment of the maximum liquid intake model provide references for the determination of the maximum liquid intake of the determination of the maximum liquid intake of the same type of inert particle fluidized bed,it provides a reference for the design amplification and operation parameter selection of inert particle fluidized bed dryer.