Model Analysis And Experimental Study On Mechanism Of Thermomechanical Refining Plate Separating Fiber

In fiberboard production, the preparation of fibers is mainly by thermomechanical refining method. This method uses the refining plate to exert refining effect to the raw materials after a short time high-temperature steaming, which contributes to the disintegration of fiber cells of raw materials, then the raw materials change into monomer fibers. Reveal the fiber separation mechanism can deeply carry out the study on the theory of fiberboard production technology, establish a prefect fiber separation theory; optimize the plate tooth structure in technology level, improve the performance of the refining plate and the quality and efficiency of fiber separation and help the energy-saving during fiberboard production. Therefore, the model analysis and experimental study on fiber separation mechanism has an important theory significance and application value.According to the fiber type and the structure characteristic of raw materials, as well as the fiberboard production technology and equipments, and combining with the characters of plate tooth structure, this paper analyzed the refining plate tooth structure influence to the mechanism of fiber separated. According to the progressive broken and dissociation process of the raw materials during fiber separation, this paper analyzed the mechanism of crush zone, coarse zone and finishing zone, as well as the forced form, strength and frequency in different zones, developed the process that the raw materials from wood chips gradually separated into fibers, analytical studied the mechanism of refining plate separated fiber in macroscopic mechanics.Using the hydrodynamics theory, this paper made a model analysis on the mechanism of refining plate separated fiber. According to the fluid kinematics theory, fibers were treated as viscous fluid, referencing to the refining technological parameters, calculation methods of density and viscosity of fiber fluid were put forward; Established a movement model including the gap, the bar angle and the width of groove, etc, and the mathematical expression of the basic rule of fiber shear flow and flow forms were obtained. Analyzed the boundary layer and the rough surface of bar influence to the velocity of fiber, the gap and the bar angle influence to the rule of fiber flow as well as the width of groove influence to the fiber flow, revealed the mechanism of these parameters in the process of refining plate separating fiber preliminarily.Combining with the fiberboard production technology and equipments, the external factors is analyzed that have influence on the quality of the fiber separated and the energy consumption in this paper. According to the fluid dynamics theory, established a mathematical model of refiner power consumption about the structure parameter of plate tooth and the motion parameter of fiber, put forward a theory model about energy consumption of the refiner and power loss of the fiber flow in the process of fiber separated, analyzed the function of refining plate tooth structure influence to the energy consumption. Based on the design parameter of plate tooth structure and the control parameter in fiber preparation, this paper put forward the evaluation parameters measuring the performance of refining plate and concurrently established the contact among the parameter of plate tooth structure, the performance of refining plate and the fiber separation quality and energy consumption.Through the experimental study on the fiberboard production, this paper analyzed the influence the opening ratios of the discharge valve (OV), the feeding screw revolution speed (SR) and the accumulated chip height (CH) to the qualified fibers(QF) and the specific energy consumption (SEC) and the total amount of fibers (TF), used multiple regression analysis method, the statistic regression equations between the predictor variables and the response variables were obtained in large sample condition. According to the measurement data of fiber size in the three samples compared with the corresponding tooth structure characters of three experimental refining plate, this paper analyzed the difference in tooth structure of refining plate influence to the dimension of fiber and the relationship between the performance of refining plate and fiber quality.The model analysis and the experimental study on mechanism of fiber separation deeply analyzed the function of refining plate during fiber separation, making clear of the working mechanism of the tooth structure parameter of refining plate by model analysis method, it provide the theoretical basis and technical support for the optimization design the tooth structure of refining plate and improved the study level of domestic thermomechanical fiber separation theory, and it provided a reliable guarantee for the optimize of fiber preparation technology and the innovation design of fiber separation equipment, and for the further improve of fiberboard quality and the energy-saving in production.