Research On Paper Ultrasonic Drying Rate And Efficiency

Ultrasonic drying is based on the principle of mechanical effect and cavitation effect of ultrasonic wave,the ultrasonic energy is converted into mechanical energy by ultrasonic vibrator,and the vibrating plate is driven by ultrasonic vibrator,as a result,it is a heating-free drying method to produce high-frequency vibration atomization to remove moisture from dried materials.Papermaking has always been one of the industries with high energy consumption,and the reason is that it consumes more energy in the paper drying stage.At present,the paper drying technology is mainly steam drying,and some of the new auxiliary drying technologies belong to heating evaporation drying,and the energy efficiency is still low.Therefore,it is particularly important to seek more efficient and energy-saving drying methods for paper production.Ultrasonic drying is characterized by no heating,high drying rate and high energy efficiency.This paper explores the drying rate and energy efficiency of paper drying by ultrasonic wave.This paper mainly carries out the following research work and draws the corresponding conclusions:(1)The ultrasonic drying device and operation flow of paper were designed and studied,and the structure,frequency characteristic and thickness of vibrating plate were tested and studied.The main operating procedures of the paper ultrasonic drying test device include ultrasonic emission source,energy conversion and paper drying,temperature measurement,moisture content measurement,and paper quality measurement during the test.The study found that in the case of ultrasonic power is 200 W,with the increase of vibration plate thickness,the best frequency decreases continuously,vibration plate thickness 1 mm and 1.5 mm,2 mm and 2.5 mm,3 mm,4 mm respectively corresponding to the best frequency of 23.6 kHz,22.6 kHz,22.6 kHz,22.5 kHz,22 kHz and 19.1 kHz,and keep the change of the nonlinear relationship between both.When the plate thickness is 2 mm,the average drying rate reaches the maximum,and the corresponding optimal ultrasonic frequency is 22.6 kHz.(2)The effects of initial moisture content,ultrasonic power,apply pressure on the surface of the paper and surface temperature of vibrating plate on drying rate of paper during ultrasonic drying were studied.It is found that the higher the initial moisture content of paper,the higher the initial drying rate of ultrasonic wave.When the ultrasonic power is 200 W,the drying rate reaches the maximum value of 0.0532 g/s in a very short time,but with the decrease of moisture content,the drying rate decreases rapidly.Therefore,it is more suitable for the paper with higher moisture content,such as the pre-drying of toilet paper.The ultrasonic drying rate first increases and then decreases with the increase of power,and the two maintain a non-linear relationship.When the ultrasonic power is 540W,the ultrasonic drying rate is the best,reaching the maximum value of 0.082 g/s.(3)An experimental study on the process of hot air drying,ultrasonic-hot air drying,ultrasonic-electric heating drying and electric heating drying of paper was carried out.It is found that when the paper is dried by hot air,the drying rate shows three stages:rapid decline——basically stable——slow decline,and the drying rate becomes faster and faster with the increase of temperature.When using the combination of ultrasonic and hot air drying paper,compared with no ultrasonic drying,the maximum drying time can save 35%under the same temperature,energy efficiency increased by 14.699%,to achieve the purpose of reducing energy consumption,and the higher the temperature of hot air,the more obvious drying time reduction.Using electric heating drying and ultrasonics combined with electric heating drying,the overall drying rate of both shows a trend of decreasing.Under the same temperature,the combined drying time of ultrasonics combined with electric heating can save up to 18.9%,and the energy efficiency increases by 6%.The enhancement effect of ultrasonic wave on paper hot air drying is better than that of paper electric heating drying,and the former energy efficiency is nearly 30%higher than the latter.