Design And Research Of Coating Dryer For Water-Soluble Coating Agent Of Preserved Egg

The preserved egg is a traditional egg product in China,which is loved by the people because of its unique taste.However,with the improvement of the people’s awareness of food safety,the coating treatment of preserved egg has gradually become a necessary part of preserved egg processing and production,but due to the differences in the physical characteristics of the coating material,the versatility of the preserved egg coating and drying equipment is poor.At present,the water-soluble coating agent is mostly sprayed manually,which results in low production efficiency and the output of coated preserved eggs can hardly meet the market needs,so it is significant to carry out research on egg coating dryers for the water-soluble coating agent of preserved egg.The research is based on the water-soluble coating agent for preserved egg developed by Hubei Shendan Company.Firstly,the physical properties of the coating agent are tested,and through the analysis of the coated preserved egg in different coating methods,an preserved egg coating dryer based on the spray coating method is developed.An air-suction method was proposed to remove the dangling droplets after spray coating,and a simulation analysis of the preserved egg spray coating model was carried out using Fluent.The main research elements and conclusions are as follows:（1）The physical properties of the preserved egg and film coating agent were tested and analysed.The test results showed that the average length of the short axis of the preserved egg was 45.00mm,the average length of the long semi-axis of the tip was37.50mm,the average length of the long semi-axis of the blunt end was 27.50mm,the surface roughness of the preserved egg shell was 4.857μm and the density of the coating agent was 1.100g/cm³.The dynamic viscosity of the coating agent was 0.107Pa.s,and the surface tension was 64.2m N/m,the contact angle of the coating agent to the preserved egg shell was 72.8°;the drying test results showed that the coating needed to be dried at25°C for more than 30 min to reach the surface dry state,and the above results provided important research parameters for the research on preserved egg coating dryers.（2）The overall structure design of the preserved egg coating dryer was carried out.The quality of preserved egg coating under different coating methods was compared,and the coating method of spraying was determined.The main structure of the preserved egg coating dryer was determined to include the spraying coating device,drying device and egg tray conveying device,and the working process of the preserved egg coating dryer was clarified;the transmission route of the preserved egg coating dryer was determined based on the modular design scheme.（3）Design and analysis of the key unit of the preserved egg coating dryer.According to the design requirements of the preserved egg coating dryer,the preserved egg spraying system was designed.Through the analysis of the spraying system,the flow rate of the water pump was determined as 10m³/h,the head as 16m and the power as 750w;according to the drying time of the preserved egg,the basic parameters of the metal conveying chain were obtained,and the length of the metal conveying chain was finally determined as 60.71m;based on the Recurdyn analysis of the spiral conveying tower The dynamic characteristics of the spiral conveyor tower were analysed based on Recurdyn,and the results showed that when the tension force of the metal conveyor chain was2000N,the metal conveyor chain would produce the phenomenon of belt turning;the temperature field of the drying chamber was simulated and analysed using Fluent,and the layout of the heater and the grid angle of 30°were determined.（4）Fluent-based simulation analysis of the preserved egg spray coating process.Proposed air-suction removal method for dangling droplets formed after spray coating of preserved eggs,and a model of preserved egg spraying coating was established to investigate the influence of preserved egg placement on the formation process of egg liquid film and the influence of suction tube parameters on the dangling droplets;the Box-Behnken test was used to sieve the best combination of suction tube parameters with the film thickness variation coefficient as the evaluation index.The results of the calculations show that the liquid film wetting ratio after spray coating is 1 for the preserved egg placed with the tip facing downwards,while the liquid film wetting ratio for the preserved egg placed with the blunt end facing downwards is only 0.836;the optimal combination of straw parameters screened by the Box-Behnken experiment is L₁=14.50 mm spacing,d=12.09 mm diameter,P=6.97 kpa working pressure,film thickness variation index The average value of the film thickness variation index C was0.647,with a relative error of 1.73%from the predicted value;the predicted value of the film thickness variation index was 0.588,with a relative error of 7.55%from the predicted value and a relative error of 9.12%from the simulated value,when the experiments were carried out using the constructed pendant droplet removal device9.12%.（5）The functionality of the preserved egg coating dryer was verified by prototype tests.The test results showed that the lowest loss rate of coating agent was 9.6%,the highest loss rate of coating agent was 16.9%,the preserved egg leakage rate was 0%,the preserved egg breakage rate was 0%,the coating thickness qualification rate was 100%,the maximum production efficiency of the preserved egg coating dryer could reach 5712pieces/h,and the drying unit is stable when it is at full load.The results show that the designed preserved egg coating dryer basically meets the design requirements.