Study Of Ash Formation Behaviors Of Rice Straw And Influence Of Rice Straw Addition On Coal Ash Deposition Behaviors

Biomass ash formation behaviors, ash deposition performances of biomass and coal during gasification were researched. The study has significant effects on large-scale utilization of biomass, reducing the damage of corrosion and reducing the loss of equipment unscheduled stop, and prevention decline of heat transfer efficiency of heat exchanger caused by ash deposition. Based on Plasma Low Temperature asher(LT aher) and muffle Furnace, biomass ash formation behaviors were studied. Ash deposition characteristics of biomass, coal and blends of them were researched by drop tube furnace(DTF) during gasification.Residence time and ashing temperature were investigated by LT asher and muffle furnace, respectively. The results indicated that with the increasing of residence time in LT asher, specific surface area, porosity and average particle size of particles increased, firstly, and then decreased, real density and average pore size of particles increased straightly. The ashing process, in muffle furnace, was severe and the temperature was high, so carbon structure frame was damaged at high temperature, shrinkage of particle volume was happened at initial stage. So as the temperature increased, average pore size and particle size decreased firstly, and then increased, porosity and specific surface area increased firstly, and then decreased.Gasification temperature and rice straw addition were researched in DTF during gasification of coal. The results showed that minerals gradually exposed on the surface of ash particles with the increasing of temperature, then ash particle's viscosity increased, which caused the increasing of ash deposition efficiency. Addition of rice straw had positive effect on coal gasification reactions and ash deposition. The lower the temperature was, the more significant the promotion was. At 1200?, when addition of rice straw was larger than 10wt%, addition of rice straw had inhibition compared with the effect of addition of 0-10w%. At the same time, there were two layers of ash deposition at low temperature deposition area. The lower layer(called initial deposition layer) composed of KC1, and residue carbon. The sticky layer can capture char and ash particles making the deposition thickness increased, it was the upper layer. The formation of initial deposits layer was the most critical step for ash deposition.