Design And Test Of Key Parts Of Rotary Continuous Carbonization Equipment

China is a large agricultural country with abundant straw resources.However,at present,straw recycling is difficult and the relevant technologies are not yet mature.Therefore,most areas in China will still be burned on-site as the main treatment method for straw,which not only pollutes the environment but also wastes energy.Using high-temperature pyrolysis technology,straw can be converted into bio-char,combustible gas,tar,and wood vinegar and other products that can be used,and can be applied in many fields such as agriculture,energy,and environmental protection.At present,the main problem of carbonization equipment is that the material transportation is not smooth and the heat transfer effect is not ideal.Based on the existing biomass pyrolysis equipment,this paper designs a four-wire screw conveyor structure and a multi-cavity swirl cascade heat transfer system aiming at the existing problems,and carries out corresponding experimental research.The main work is as follows:(1)Combine the pyrolysis principle and the carbonization process of biomass,and consult the literature to clarify the influence of heating temperature,reaction time,and system pressure on the quality of biochar.Based on the existing process scheme,formulate and refine Sealing feed,material drying,low-oxygen pyrolysis,thermal insulation carbonization,cooling discharge and pyrolysis by-product heating,etc.,meet new design requirements.Based on the physicochemical properties of pyrolysis gas,a gas purification and separation and reuse program was proposed and selected.(2)Aiming at the problem of unsteady material transportation in existing carbonization equipment,a four-wire spiral feeding structure was designed.The spiral vane was combined with the copy board so that the spiral copy board was embedded in the inner wall of the rotary drum and the material was pushed forward.At the same time,turning up and down,the heating is more uniform,and the screw shaft can also avoid the limitation on the size of the equipment due to the deflection problem.Because the screw turns into a discontinuous type,a multi-line design can be realized,and the material conveying amount control accuracy is higher.(3)Aiming at the problem of unsatisfactory heat transfer performance of existing carbonization equipment,a multi-cavity cyclone cascade heat exchange system was designed.The rectangular flute structure was adopted to divide the heat exchange flue gas chamber into four parts,and the spiral baffle heat exchange was achieved.The combination of the structure and the shell-and-tube heat exchanger enables the heat transfer effect to reach the carbonization requirements;and the Fluent software is used to simulate the velocity field and the temperature field of the heat exchange structure,and the flow characteristics and temperature distribution of the high temperature heat smoke are obtained..(4)The equipment performance indicators,the feeding capacity of the four-wire screw conveyor system,and the stability of the multi-cavity cyclone heat exchange system were tested respectively.The test results showed that: biomass continuous pyrolysis carbon-gas-oil cogeneration The raw material handling capacity of the test system is 28.1 kg/h,the biogenic carbon yield is 31.4%,the gas calorific value is 16.3 MJ/Nm3,the temperature control precision is ±10°C,the pressure control accuracy is ±10 Pa,and the four-wire spiral feed structure is The control of the material residence time is relatively accurate,and the pyrolysis gas combustion produced by the raw material pyrolysis can satisfy the continuous and stable operation of the equipment.All technical indicators have reached the overall design goals and requirements.