Thermochemical Simulation And Optimization Research Of The Solar Driven Fluidized Bed Biomass Gasifier

In order to achieve the national goal of"Double Carbon"and reduce the pressure of national natural gas import,the utilization of renewable energy represented by biomass gasification will flourish.However,the traditional biomass gasification device using fuel to provide the heat for gasification will produce additional by-products and lose a lot of heat.In contrast,solar energy gasifier stores solar energy into biomass syngas by thermochemical means of heat transfer and gasification,which improves the energy taste of solar energy and saves fuel,which is a research hotspot in the future.The collector subsystem of solar dish collector is coupled with the biomass fluidized bed gasification subsystem in this paper.The integrated system mainly consists of heliostat,parabolic dish collector and fluidized bed gasifier.The structural parameters of the two subsystems are designed,and the thermochemical model of the system is established by using finite element analysis software and computational fluid software.The performance evaluation index of biomass fluidized bed gasifier system driven by solar energy was established.The simulation reliability of the system is verified by comparing with references.The system operation under 9.20 MW/m~2 solar irradiation is taken as the design condition,and the solar energy heat distribution in the design condition,the syngas distribution in the longitudinal interface of the gasifier,the static temperature and pressure are simulated.The gasification performance of the system under variable conditions(rim angle,mass ratio of steam to biomass feeding,biomass feeding rate and solar irradiation intensity)was analyzed.The influence trend of key parameters on the mole fraction of gas components,lower heat value of syngas,carbon conversion efficiency and gasification efficiency were obtained.The results reveal that the coupled system implements the best gasification performance in the design conditions which the rim angle,steam-to-biomass mass flow ratio,and biomass feeding rate are set at 60°,0.4,and 2.5 g/min,while the LHV,carbon conversion,and gasification energy efficiencies are11.51 MJ/m~3,78.17%,and 93.01%,respectively.The overall energy efficiency considering solar energy is 30.79%.Finally,the structure of the sub equipment of the fluidized bed gasifier is optimized to achieve the optimal gasification performance under certain boundary conditions.Single variable method was used to investigate the gasification performance of the gasifier under different ratios of bottom diameter of conical contactor to oxidant inlet diameter,ratios of oxidant inlet diameter to biomass particle average diameter,contact angle,reactor diameter and reactor height.The optimum design structure parameters of the gasifier are gained.The diameter of oxidant inlet is 0.0056m,the diameter of bottom of cone contactor is 0.014m,the average diameter of biomass particles is 0.00016m,and the diameter of reactor is 0.1100m.This paper is aimed at providing methods and basic data for the design of engineering solar driven biomass steam fluidized bed gasifier.