Design and experiment of rapid aerobic fermentation equipment for agricultural waste

In view of the problems existing in the actual production of aerobic fermentation, such as unsuitable fermentation equipment, large area, long fermentation cycle and low degree of automation, a horizontal cylindrical fermenting tank, with the effective volume of 3 m³ was designed by increasing the fermentation area, reducing the depth of materials, improving the uniformity of mixing and optimizing the fermentation cycle. According to the heat transfer and heat loss model, the heat dissipation mechanism of the fermentation material was analyzed, the shape design of the tank was further optimized, and the automatic control system was designed. According to the characteristics of the selected fermentation materials, such as high viscosity, poor fluidity and easy attachment to the tank wall, a wide-narrow double-helical agitator was designed, and the finite element analysis and material stirring uniformity analysis were carried out on it. The maximum simulated stress of the stirring shaft was 4.23 MPa, the optimum rotational speed of the stirring shaft was 7.7 r/min. The equipment was tested in an organic fertilizer plant, using mixed feces, corn straw and pumpkin stems and leaves as fermentation materials. No manual intervention was required during the operation process and the fermentation parameters are controlled with high precision. After the fermentation, the organic matter content of the product was as high as 51%, the nitrogen, phosphorus and potassium content was 8.8%, the pH value was 6.8, the carbon nitrogen ratio was 23, the arsenic content was 11 mg/kg, the cadmium content was 3 mg/kg, the mercury content was 1.7 mg/kg, the lead content was 27 mg/kg, and the mortality rate of pest eggs was 97%, the grain size is 9 mm, the color is dark brown, which meets the relevant requirements of organic fertilizer products, and the fermentation efficiency is five to ten times higher than that of natural fermentation.