Research On Slurry Ability, Co-gasification And Chromium Migration Of Waste Biomass And Coal

Based on the presence problems of co-utilization between waste biomass and coal, the effect of ball milling on the slurryability of Biomass-Coal-Water slurry and the volatilization behavior of chromium during co-gasification process of tannery sludge and coal are studied. The main contents are summarized as follows.Using the pretreatment method of ball mill, the slurry-abilities and rheological properties of biomass-coal-water slurry have been investigated, which have also been compared with coal-water slurry. The results show that the yield stress, thixotropic and stability of Biomass-Coal-Water slurry increase significantly comparing with Coal-Water-Slurry. The slurry ability could be improved by prolonging the milling time.Based on the experimental platform of high-furnace fixed bed reactor, the effect of tannery sludge on the volatilization rate of chromium in coal has been studied during pyrolysis and gasification process. It is found that the volatilization rate of chromium in coal is larger than in tannery sludge. The volatilization rate of chromium increases firstly and then decrease with enlarging the tannery sludge proportional or increasing temperature during gasification. The existing state of chromium elements in coke and ash has been studied with Tessier sequential extraction procedure. It was found that most of them bound in a stable form. It is clearly that the chromium element in a more stable form in ash than in coke. The XRD analysis on ash shows that the mineral types of tannery sludge and coal are different. The diffraction intensity is enhanced of chromite massive isometric, larnite and augite by increasing the proportion of tannery sludge. Furthermore, the type of mineral in ash samples with increasing temperature is changeless, while the diffraction intensity is gradually weakened.Effect of tannery sludge on coal gasification kinetics with pressurized thermal balance has been studied. Adding tannery sludge into coal could increase specific surface area, reduce the average pore size and short the gasification reaction time. The increase of temperature could accelerate gasification reaction rate. The random pore model is found to be suitable for simulating the reaction rate of gasification and carbon conversion rate.