Design And Experiment Of Automatic Composting Reactor

The harmless and resource utilization of agricultural organic waste plays an important role in alleviating the contradiction between environment and resources.Composting,as a safe and effective treatment method of agricultural organic waste,can reduce the pollution of agricultural organic waste to soil,water and air,and realize the transformation of waste to resources,which is conducive to reducing the application of agricultural fertilizer.Therefore,in view of the current situation and development direction of agricultural organic waste treatment,it is of great practical significance to develop a simple composting reactor in line with China’s national conditions.In this paper,an ultra-high temperature composting reactor with automatic heating and stirring was designed(1)Overall design of composting reactor.Combined with the ultra-high temperature composting process and the function and performance requirements of the composting reactor,the horizontal composting reactor was used as the design scheme of the ultra-high temperature composting reactor.In order to meet the requirements of uniform mixing and heat transfer performance,the double spiral belt type was selected as the agitator type,and the U-shaped integral jacket was selected as the heat transfer element of the composting reactor.(2)Design and simulation analysis of key components of composting reactor.Based on the overall scheme of composting reactor,the main design parameters of the reactor were determined,in which the design volume was 1 m~3and the design temperature in the jacket was 140℃;through theoretical calculation and consulting the mixer design manual,the relevant dimensions of the reactor body and the mixer were determined,in which the inner diameter of the cylinder was 856 mm,the length of the cylinder was 1800 mm,the height of the cylinder was 950 mm and the inner diameter of the jacket layer was 956 mm The height of the jacket is 1050 mm,the diameter of the big screw belt of the agitator is 850 mm,and the pitch is 1700 mm.The heat transfer area of the jacket is checked,and the heat transfer area meets the design requirements;the modal simulation of the stirrer is carried out based on Ansys,and the critical speed of the stirrer is 1200 r/min,and the stirring speed is 120r/min according to the requirements of stirring and heating performance;the stirring process of the reactor is simulated by fluent,and the stirring power is about 12.81 k W,and the velocity field in the reactor is analyzed The results show that the agitator can realize the uniform stirring of the material,and the unidirectional rotation is conducive to the discharge of the material,which verifies that the design scheme of the reactor can meet the functional and performance requirements.(3)Design and simulation analysis of composting reactor control system.On the basis of the overall scheme of composting reactor and the structure of key parts,after comparing the common control system schemes,it is determined that the pneumatic circuit is used to control the state of the feed and outlet,the time relay is used to control the composting reaction time,the forward and reverse controller is used to control the intermittent mixing of the agitator,and the temperature controller is used to control the heating of the heat transfer oil type.The pneumatic control circuit and control circuit are designed,and the pneumatic circuit and control circuit are simulated in Automation Studio.The simulation results show that the control system scheme meets the design requirements.(4)Trial production and verification test of composting reactor.The results of temperature and humidity changes in the reactor during composting show that the equipment can operate stably with fast heating speed and good heat transfer performance;The moisture content,p H value,electrical conductivity and nitrogen,phosphorus and potassium content of compost were measured.The results showed that all the compost indexes met the requirements of organic fertilizer maturity;The results showed that the seed germination rate,plant stem length and seed germination index were close to the substrate,and the seed germination coefficient reached the requirement of harmless composting.The seed germination rate,plant stem length and seed germination index were improved after natural composting,The results showed that compost could meet the requirements of plant growth and development.Through the above experiments,the feasibility of composting reactor is verified,and the quality of compost meets the requirements.