Research And Optimization Of Dry Rendering Process Of Diseased And Dead Animals

China is a country with a large population and a huge demand for meat.In order to maintain a stable supply of meat,we need a large scale of breeding.However,due to the spread of various diseases that lead to the unnatural death of a large number of animals,and the current level of harmless treatment in China is bad,it often causes public health safety hazards.Currently,there are many harmless treatment methods,such as incineration,burial and fermentation,etc.However,these conventional treatment methods often lead to environmental pollution and low treatment efficiency.Rendering process is a kind of harmless treatment method with low environmental pollution,high treatment efficiency and abundant by-products.However,the rendering process in China is not uniform,and the quality of by-products is uneven.Therefore,this paper analyzed the advantages and disadvantages of the existing dry rendering process,established a process evaluation model,and studied the physical properties of pork under different holding time after the rendering temperature reaches the standard,and optimizes the parameters of the rendering process.The characteristics of materials during hot air drying and vacuum drying after rendering treatment were studied.At the same time,the hot air drying model of hot air drying was established,and the drying parameters were optimized to improve the overall efficiency and by-product quality of the drying process.The main contents of this paper are as follows:(1)Through the analysis of sterilization mechanism,it was concluded that temperature is the main influencing factor to kill bacteria.Analyzed the difference between the existing normal pressure rendering process and the high temperature and high pressure rendering process in each module,discussed the advantages and disadvantages of different processes,according to the existing rendering process,introduced the analytic hierarchy process,established the process evaluation model established a process evaluation model and concluded that the drainage high temperature and high pressure rendering process had the best comprehensive benefits.(2)Under the condition of ensuring sterilization,taking pork as the research object,the elastic modulus and hardness of pork after cooking were measured and calculated by setting the non-assimilation holding time(30min,45 min,60min and 90min).It was concluded that when the temperature in the storage barrel is ?140? and the pressure is ? 0.4MPa,the material has the best comprehensive performance after 30 min maintenance,which can obtain high-quality meat and bone meal and grease,reduce the separation process of oil residue,and save the cost.The effects of initial moisture content,temperature of heat-conducting oil and material size on rendering time,hardness and modulus of elasticity were studied by orthogonal experiment.Determine the rendering process parameters with the shortest time and the optimal rendering process parameters of the by-products.(3)The influence of process parameters of hot air drying on drying process was studied.The results showed that the influence of temperature on drying rate was greater than that of wind speed in the range of parameters set by experiment.The higher the temperature,the higher the wind speed,the faster the drying rate The heat and mass transfer model of hot air drying of the material after rendering was established by numerical simulation,and the changes of internal temperature and moisture of the material were analyzed.The drying curve was fitted by 10 thin-layer drying models.The Logarithmic model was the best,and the test was verified to more accurately control the moisture content of the hot air drying process and further improve the quality of by-products.(4)The vacuum pulverization drying to rendering technology was introduced for the first time.The effects of vacuum degree,vacuum holding time and atmospheric pressure holding time on the drying process of the material were studied.It was concluded that the vacuum pulsation drying has the fastest drying efficiency when the vacuum holding time is 6 min and the normal pressure holding time is 3 min.The moisture diffusion coefficient and activation energy of the material during constant vacuum drying and vacuum pulsation drying were calculated.The model was fitted to the drying curve,and the Weibull model and the Page model with higher degree of model fitting were selected for regression analysis of model parameters and experimental parameters.The model's research results were transformed into tools for describing,predicting,analyzing and optimizing the material drying process,thereby more accurately controlling the moisture content of the material in the vacuum pulsation drying process and further improving the quality of by-products.