Design And Research On Biomass Pneumatic Conveying System For Fast Pyrolysis

Biomass pyrolysis feeding process is generally instable and difficult to be controlled or monitored due to the different characteristic of biomass and the complexity of gas-solid phase feeding process,which may affect the industrial application.In order to improve system stability and make mass flow rate controlled and monitored smoothly,tests adopting typical woody biomass for pyrolysis as physical property testing materials and larch saw dust as heating materials were carried out.A pulse pneumatic conveying system was developed.The influence of parameters on feeding rate and mass flow rate were investigated.An on-line monitor system based on photoelectric coupling was developed.The main research contents and conclusions are as follows:(1)According to biomass pyrolysis characteristics,a heating experiment of biomass was carried out.A pulse pneumatic feeding equipment has been designed,and influence of struction parameters on the effect of feed has been analyzed.This equipment meets well with pyrolysis feeding requirements.By adjusting the cycle of solenoid valve,the linear rising area of mass flow rate can be increased.(2)By researching on the flow and heating characteristics of biomass in the feeding tube,the main reason of caking,carbonization and blockage can be concluded as that the retention and heating of underpowered particles conveyed unstably may dissolve out liquid and adhere to each other.The adhesion degree of typical material between particles is in the order:Compose wood>Chinese catalpa>Cedar>Larch.(3)A two-stage pulse pneumatic fast pyrolysis conveying system has been developed,and the corresponding frequency control method was proposed.The average mass flow rate is about 20 g/min when two-stage pulse jet frequency matches the best.(4)An on-line monitor system and controlling system for biomass pyrolysis feeding have been realized by combining infrared lasers and light sensors in shading tube.The results show that the average electricity is negatively related to the feeding rate;Mass flow rate increases from the lower to the upper in tube;The farther the distance away from the nozzle,the smaller the mass flow rate and the more dispersed the particles;The average mass flow rate is about 0.2～0.6 m/s(the diameter of tube is 20 mm).