| Mechanized recovery of residual film is an effective way to solve the pollution of residual film.The spring-tooth residual film collector has the characteristics of simple structure and high recovery rate.However,the phenomenon of residual film winding and picking up mechanism generally occurs in the field operation process,and the impurity rate of the recovered residual film is high.In view of the above problems,a new idea of " mechanical stripping + air-assisted stripping + air cleaning " collaborative operation is proposed.Through theoretical analysis,simulation and experimental research,a stripping and impurity removal device is designed.The interaction between the structural parameters and working parameters of the stripping and impurity removal device and the effect of stripping and impurity removal is discussed.The separation mechanism of membrane and impurity is revealed,which solves the difficulty of stripping the elastic tooth residual film recovery machine and reduces the impurity content of the recovered residual film.The main research work and conclusions of this paper are as follows:(1)Material characteristics and suspension test.The field investigation of the operating environment of the recycling machine in the test area was carried out,and the basic data of cotton plant spacing,row spacing,actual width of the film,thickness of residual film and soil were obtained,which provided theoretical support for the design of key components.The existing elastic tooth type residual film recycling machine was used to recover the residual film.The recovered residual film materials were classified and weighed,and the proportion of residual film,straw and soil particles of different sizes in the material was obtained.According to the statistics of the proportion of the component size of the membrane impurity mixture,the samples were collected for the suspension velocity range test.The suspension velocity of the residual film,cotton stalk and soil particles ranged from 1.60 to 2.80 m/s,5.90 to 10.20 m/s and 8.98 to 12.80 m/s,respectively,which verified the feasibility of air separation.(2)Design of membrane removal device and analysis of membrane removal process.The requirements of stripping,auxiliary stripping and impurity removal were clarified,and the stripping and impurity removal device was designed.By analyzing the migration conditions of the residual film between the elastic tooth and the stripping tooth plate during the stripping process,the stripping tooth plate is determined to be used for stripping;according to the positional relationship between the stripping tooth plate and the elastic tooth chain rake,the differential equation of the stripping tooth plate line is established and the tooth plate line function is solved.According to the arrangement of the pick-up elastic teeth,the de-filming tooth plate is arranged.Based on the comprehensive analysis of the stripping and impurity removal process,the relative position relationship between the stripping tooth plate and the air collecting cover plate is obtained.The movement of the material in the impurity removal zone was analyzed,and the requirements of membrane separation were determined,which laid the foundation for the numerical simulation.(3)The flow field simulation of the membrane removal device.A method for calculating the parameters of the equivalent moving sphere is proposed,and the parameters of the air separation equipment are solved by combining the computational fluid dynamics discrete phase model(CFD-DPM).The simulation calculation method verification test bench was made according to the impurity removal principle of the membrane impurity removal device.The motion analysis of the residual film and straw in the airflow field of the suspension test bench and the verification test bench is carried out respectively,and the calculation formula of the equivalent motion sphere simulation parameters is derived and the specific values are obtained.By constructing the CFD-DPM coupling model,the motion of the equivalent moving sphere in the verification test bench is numerically simulated,and the critical speed of the centrifugal fan required for the separation of residual film and straw under different parameters is solved.The centrifugal fan speed obtained by simulation is verified by bench test under the same conditions.The numerical error between the simulation value and the measured value is less than 10%.The simulation value has certain accuracy,which proves that the research method and the impurity removal theory are feasible,and the causes of the error are analyzed.The simulation calculation method is used to simulate the movement of the residual film in the fluid domain of the wind collecting hood plate,and the wind speed range of the outlet of the wind collecting hood plate is calculated.(4)Field experiment.According to the principle of Box-Behnken experimental design,three-factor and three-level quadratic regression experiments were carried out with forward speed,chain rake speed and fan speed as experimental factors,and film wrapping rate and residual film impurity rate as response values.The response surface regression model was established,and the factors and their interactions were analyzed.The results show that the influence of various factors on the film winding rate from large to small is: forward speed,chain rake speed,fan speed;the influence of various factors on the impurity content of residual film from large to small is: fan speed,chain rake speed,forward speed.The regression equation was optimized by using the optimization function of Design-Expert software.When the forward speed of the machine was 5 km/h,the chain rake speed was 236 r/min and the fan speed was 1978 r / min,the film wrapping rate was 0.42%,and the residual film impurity rate was 9.31%.The field experiment was carried out with the parameters after rounding,and the average value of the film wrapping rate under the parameter combination was 0.61%,and the average value of the residual film impurity rate was 9.56%,indicating that the optimization scheme of the device was feasible.The comparison test was carried out,and the improved elastic tooth type residual film recycling machine was significantly improved in film removal and impurity removal performance. |
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