Study On Paper Drying Process And Paper Properties Based On Ultrasonic

With the goal of saving energy and reducing consumption,protecting the environment and ensuring product quality,this paper innovatively applies fast and energy-saving ultrasonic drying technology to the high energy-consuming process of papermaking(paper drying unit).By studying the process of ultrasonic drying paper and its influence on the properties of paper,the feasibility and applicability of its application in the process of paper drying were explored.The specific research contents and main results of this paper are as follows:First of all,according to the research needs of the subject,a small experimental table for ultrasonic drying paper was designed and constructed,and the effect of drying paper under different plate thickness was explored through Finite Element Analysis and experiments.The results show that the ultrasonic field radiated by the plate with different thickness is the same,and the amplitude in the middle region is the highest,and the surrounding area decreases with the increase of the distance from the center.When the 2mm-thick plate is drived by ultrasonic,the change of plate surface amplitude is relatively smooth.The changes of moisture content and temperature of the paper are closely related to the vibration characteristics of the board.The greater the amplitude,the stronger the ultrasonic drying ability,the faster the heating up of the paper.When the 2mm-thick plate is drived by ultrasonic and within 30s of the drying time,the regional dehydration rate of the paper is within 0.5%and the rising trend of paper temperature is gentle.However,the plate driven by a single transducer has a bad influence on the transverse temperature of the paper,which can be eliminated by using the transducer array and further improve the intensity of ultrasonic.Then,on the basis of the previous experiments,the paper drying process was defined according to the ultrasonic mechanism,and the drying mathematical model was established based on the principle of mass and energy conservation.The results show that the process of ultrasonic drying is ultrasonic drying in the initial stage and electrothermal drying in the later stage,and the mass transfer is in the form of water mist seepage and water vapor diffusion.The ultrasonic ability is positively correlated with the moisture content of the wet paper(dry matter)and negatively correlated with the paper temperature,and the two are coupled with each other.The drying process is mainly in the deceleration stage,and the drying curve obtained by the mathematical model is consistent with the trend of the measured curve well.Finally,the applicability of ultrasonic drying paper was explored by comparing the properties of ultrasonic drying paper and electrothermal drying paper.The paper was dried under different ultrasonic power,different drying time and the combined drying with electrothermal heating at different temperatures.The results show that,compared with electrothermal drying,the tensile strength of the paper obtained by ultrasonic drying is relatively increased by 1.7%,the tearing strength is increased by 1.5%,and the porosity is decreased by 30.7%.It can be seen that the propagation of ultrasonic in the wet paper will have a certain effect on the fiber itself,the structure of the fiber and the degree of bonding between the fibers,thus these affect the various properties of the paper.In addition,increasing the ultrasonic intensity can reduce the thickness and porosity of the paper,and enhance the tightness,tensile strength and tearing strength degree of the paper.With the increase of drying time,the paper thickness and porosity decreased slightly,and the strength index of the paper sheet first increases and then decreases slowly.It is not conducive to the paper properties with the increase of electrothermal,and the subsequent drying of the wet paper sheet after ultrasonic drying needs to follow the temperature control curve of traditional dryer drying in order to ensure the quality of the paper.These can provide an experimental basis for the application of ultrasonic drying technology in practical engineering.In summary,the ultrasonic drying technology is suitable for the paper drying process.It has no obvious negative effect on the general and physical properties of the paper,and is beneficial to the structural properties of the paper,which is mainly due to the positive effect of ultrasonic at the initial stage of drying.This can provide a good technical innovation for saving energy and reducing consumption in the papermaking process.