Design And Experiment Of Pilot Test Platform For Vertical Batch Dry Distillation Of Discarded Fruit Tree Branch

The annual pruning volume of orchards nationwide is about 90 million tons,of which the annual pruning volume of apple trees in Shaanxi Province is about 4.5456 million tons.The huge amount of pruning branches of fruit trees cannot be processed in a timely and reasonable manner,and the existing biomass carbonization device requires a large amount of consumption The external heat maintains the energy requirements of the carbonization reaction.Aiming at the characteristics of apple tree pruning and the characteristics of pyrolysis carbonization reaction,and based on the principle of improving the utilization efficiency of biomass energy,a vertical batch dry distillation pilot platform for fruit branches was developed,equipped with a gas-liquid product condensation purification and separation device,and Wood gas is used as a fuel to provide a heat source for the carbonization process to achieve the purpose of self-sustaining operation of the retort pilot platform.Through the design of the fruit branch vertical batch retort pilot test platform,prototype trial production and testing,thermal balance analysis and simulation,it provides a theoretical basis for practical applications.The main research contents and results are as follows:(1)Design of pilot test platform for vertical batch dry distillation of discarded fruit tree branch.In view of the high external energy consumption of existing carbonization devices,the design goals,process principles and structural principles are determined.Combining relevant theoretical knowledge,design the main area structure and size parameters,and design the control part according to the process flow.The design results are as follows:The diameter of the main carbonization pipe in the carbonization zone of the dry distillation pilot platform is 200 mm and the length is 1300 mm.The diameter of the furnace is 400 mm,the height is1000 mm,and the thickness of the insulation layer is 100 mm.Three sets of wood gas burners are used for heating,the wood gas nozzle diameter is 6.42 mm,and the air nozzle diameter is18.17 mm.The pyrolysis gas condensing zone adopts a 3-stage single-shell-pass single-tube-tube condenser.The wood gas purification area uses water washing tanks and activated carbon adsorption tanks to remove impurities and moisture.The oil-liquid separation zone adopts the static method to separate wood vinegar and tar.A 2 k W ZYL type heating furnace is used for secondary cracking,and two sets of GHBH type high-pressure blowers with a rated power of0.25 k W are used to pressurize wood gas and air.The control system uses Siemens SIMATIC S7-200 SMART series PLC as the control core.The Utility Manager configuration software is used to develop a human-computer interaction system.It is divided into automatic control and manual control modes,and can be displayed in real time,Store and export data.(2)Trial-manufacture and test of pilot test platform for vertical batch dry distillation of discarded fruit tree branch.According to the design parameters,the dry distillation pilot plant was processed,assembled and debugged.The pruned branches of apple trees were used as raw materials.Under specific dry distillation process conditions,the pyrolysis and carbonization of the apple pruned branches in the prototype and the carbonization area of the dry distillation pilot platform And pyrolysis gas condensation zone temperature change,carbonization product yield and solid-phase product biochar performance test to reflect the comprehensive performance of the experimental platform.The results showed that the biochar yield of the retort pilot test platform was 32.71%,and the yield of liquid products was 31.7%.Fruit wood biochar has a rich pore structure,with a calorific value of 28.53 MJ/kg and a fixed carbon content of 81.16%.The maximum temperature in the furnace of the carbonization zone is602.5℃,the maximum temperature in the carbonization pipeline is 503.8℃,the outlet temperature of pyrolysis gas is 205.2℃,the temperature of wood gas after condensation is about 0℃(outdoor temperature-2℃),and the calorific value is 20.21 MJ/Nm~3.(3)Analysis and simulation of heat balance of pilot test platform for vertical batch dry distillation of discarded fruit tree branch.Through the calculation of heat transfer,the relationship between the input heat and the output heat supply of the fruit tree pruning self-sustained dry distillation pilot platform was compared,and the temperature field and flow field of the carbonization zone were simulated based on ANSYS Fluent.The results show that the fuel quantity required by the retort pilot test platform is 4.58 m~3,which is less than the output of wood gas produced by the carbonization of each batch of raw materials.Therefore,in addition to the external heat source required for the first operation,the energy for each subsequent carbonization will come from Biomass raw materials and wood gas produced in the previous batch.Simulation analysis shows that when the wood gas is burned on the dry distillation pilot platform,the temperature in the furnace is about 605℃,and the temperature in the carbonization pipeline is about 517℃.