Design And Research Theory On The Inner-Tank Double Heating Type Biomass Pyrolysis Reactor

The domestic and foreign research status of biomass energy utilization technology shows that the technology of biomass pyrolysis for producing bio-oil is one of the most promising technologies of biomass energy utilization. Biomass pyrolysis reactor is the most important part in the pyrolysis process equipments. The reactor’s design parameters, internal structure and so on, exert a variety of effects on the conversion of pyrolysis products, manufacturing cost and energy consumption of the system equipments. The reasonable pyrolysis reactor can achieve flash temperature of biomass particles and rapid separation of gas phase, and obtain high yield and high quality of bio-oil. The selection and design of the reactor system for biomass pyrolysis oil is a key link in the process of experimental study. Therefore, design of pyrolysis reactor and research of related theory is a key link of the technology of biomass pyrolysis for producing bio-oil.Nowadays biomass pyrolysis reactor exists a lot of problems such as high manufacturing cost, low heating efficiency, low rate of oil, low life, and engineering amplification difficulties. On the basis of characteristics and disadvantages of the existing biomass pyrolysis reactors, this paper presentes a kind of liner type double heated biomass pyrolysis reactor, and studies the related theories. This reactor with uncondensable gas as the fluidizing gas and quartz sand as bed particles, uses the outer hot flue gas and liner uncondensable gas preheated by hot flue gas to heat the biomass particles and bed particles. On the one hand the reactor can improve the heating efficiency, on the other hand total height of biomass pyrolysis equipments for producing bio-oil can be reduced by about50%, which greatly reducing consumption of steel and cost of bio-oil. This can provide theoretical and technical supports for development of biomass pyrolysis reactor and associated equipments, and engineering amplification.Based on biomass pyrolysis mechanism of preparing bio-oil, and considering the fluidized bed reactor is widely used and the technology is mature, but the height of pyrolysis system equipments is high, manufacturing cost is high, realization of engineering magnification is difficult because of the low heating rate low and needing external heating, and lack of uniform design model, this paper presents a calculation model for designing fluidized biomass reactor, which provides a theoretical reference for development of new type reactor. Then uses the calculation model to optimizing related design parameters of the liner type double heat type of biomass pyrolysis reactor, with the minimum residence time of gas phase as objective function.Based on the conservation of energy, analyzes the heat balance of pyrolysis system, studies heat transfer model between bed and wall, heat transfer model between particles, and convective heat transfer model, combining the characteristics of heating and heat transfer.Then analyzes and determines the reactor heat balance equation and heat balance condition of biomass fast pyrolysis reaction, which laying a foundation for further simulation research on heat and mass transfer process in the reactor.On the basis of the theory of fluidization, establishes cold test bench of liner type double heated reactor, researhes the influence of the fluidized quality in different experimental working conditions, such as different inlet air velocity, particle sizes, biomass particle types, and heat carrier particle mixing ratio, particle stack height and opening rate of distribution plate. Then studies the influence law of fluidization quality with various factors, which providing references for design optimization of biomass pyrolysis reactor.The gas-solid two-phase flow equation is established based on gas molecular motion theory and particle dynamics method, simulation of cold fluidization process in the reactor is analyzed by the simulational software, and then numerical simulation of different working conditions and operation conditions are studied comparatively. Comparing with the cold experimental data, verifies the correctness of the numerical model.Then considering the reactor heat transfer law, hot-solid coupling model and thermal-flow coupling model is established, and the multi-physical field coupling simulation is studied for the pyrolysis reactor. The reactor wall and internal temperature field and temperature gradient distribution is received, which meets biomass pyrolysis conditions. The simulation results can provide reference basis for thermal state experiment, and verify that the design of the reactor is feasible and can achieve efficient biomass pyrolysis, provide theoretical basis for engineering amplification. This can provide a reference for further thermal state experiments, proves that the new reactor is feasible and can achieve efficient pyrolysis, and also can provide the theory basis for project goal such as complex dynamic performance simulation of internal reactor and optimization design.