| Thermosetting building plastic products have excellent characteristics such as heat resistance,water resistance,and corrosion resistance.In recent years,they have been widely used in the construction industry,but there are more and more waste plastic products that are scrapped.It is a serious threat to the country's ecological construction and environmental sustainable development.At present,due to the tight internal network structure of thermosetting building plastics and the difficulty of secondary recovery,direct disposal by landfill and incineration is mainly used,resulting in a relatively low recycling rate.Therefore,it is of great significance to explore new recycling methods and efficiently reuse waste thermosetting plastics to help technological innovation and economic development.Based on the premise of mixing and recycling thermosetting and thermoplastic powders,taking rigid polyurethane foam insulation board as the research object,the self-designed integrated dust-free crusher is used as the crushing tool,and the mechanical and physical recycling method is adopted.Thermosetting building plastic recycling and discrete element parameter calibration and calibration methods,designing a crushing model based on Hertz-Mindlin(with Bonding)theory,and carrying out numerical simulation and optimization of DEM-CFD gas-solid coupling field Chemical instrument characterization to explore the degradation effect of recycled materials after optimization.The main research work is as follows:(1)Design polyurethane crushing model.For the contact parameters between particles,the parameter optimization process of BP neural network is optimized based on multi-objective genetic algorithm(GA).in order to obtain the bonding parameters between particles,the critical strength of the material is used as the calibration reference value,based on theory and simulation Combining simulation methods to solve bonding parameters.(2)DEM-CFD two-phase flow calculation.Using the different rotation speed and number of teeth of the rotor cutter teeth as the optimization variables,multiple sets of gas-solid coupling numerical simulations are carried out.The calculation results show that when the rotation speed reaches 4500 rpm,the negative pressure area in the crushing chamber is relatively obvious,which is convenient for material inhalation.When a three-blade crusher is used,the air field velocity in the cavity changes slowly,and the particle size distribution of the material powder after crushing is relatively uniform.(3)Validation of the optimal set of process parameters.In the actual crushing test,within the range of 10 min to 40 min,control and change the material crushing time and carry out continuous crushing test.The impact of crushing time on the cumulative distribution of the material is more obvious.At the same time,the crushed powder was characterized and tested by means of infrared spectroscopy.Its ATR-FTIR spectrum showed that at 1226.5cm-1 wave number,the carbamate-based C-O stretching vibration peak significantly changed.The results show that the cross-linking density of the waste thermosetting plastics is broken,and a large number of renewable polymerized active groups are obtained,which provides a theoretical reference for the feasibility of recycling and recycling of thermosetting building plastics.Figure[55] table[7] reference[80]... |
PDF Full Text Request