Experiment Study And Simulation Of Fluidised Bed Gasification Of Biomass Briquettes

The biomass briquettes is pretreated by natural drying. Briquettes moisture will balance with surrouding in about 3~4 days whatever types of biomass.There's no more change in balancing again when relative humidity is decreasing.A bubble fluidized bed(Φ300mm)is designed to take fluidization experiment of biomass briquettes.The fluidization status of briquettes mixed with sand is depending both on which's density and cross section area.When the density is low(0.5g/cm3),cross section area affects more than density,which is reversed when higher(1g/cm3).Preheating sand is a time-comsuming process during gasification experiment at fluidized bed(Φ200mm),for a better effect preheating time is no more than 1h.The gasification between briquettes and bulk ones is nothing different based on the same work condition,which's depending on types of materials.Syngas from briquettes can keep burning for 50-60s,which is longer than bulk ones. There is some combustible materials in the ash which's precent is about 25wt%.And this proportion will decrease with materials cycling system installed.The gas temp is decresing 15% and pressure drop for 0.5kPa when long distance transferring calucalated by a reliable method.Simulation and sensitivity analysis of biomass gasification based on fluidized bed using Aspen Plus is taken,and gasification model is proved by selecting pine and wheat straw(WS).Some parameters that is difficult to study are made to research through simu- lation.It is suggested that the best ER for pine gasification is about 0.2~0.25 and 0.3~0.35 for WS's.Adding additional steam have negative effect on pine gasification.This is similar to WS's for which with a small peak of gasification efficiency when S/B is 1.Air preheating is helpful but pine gasification is less sensitive than WS's.Air is economically heated up to 600-700℃.As high water content is harmful for gasification,it is suggested that limitating it under 20%.Pressure promotion in some extent is effective on biomass gasification(15 bar for pine and 19 bar for WS),beyond which is not remarkable.