Study On The Combustion Characteristics Of Coal Blent With Biomass In Oxygen Enriched Conditions

In this article, the ASPEN PLUS software was applied to the oxygen-enriched combustion process simulation and product analysis of four different biomass (ricestraw, wheatstraw, platanewood and larix) and coal in two different metamorphic degrees (bituminous coal, lean coal) and their blending, and influences of temperature and oxygen concentration on the combustion was obtained; the combustion characteristics were analyzed through thermal analysis technique, and influences of parameters including blending ratio and oxygen concentration on their combustion characteristics were discussed, and in further, the dynamic analysis was carried out and the dynamic characteristics were obtained; finally verification experiment was conducted in the mini-fluidized-bed combustion system, and the combustion rate was determined and the results were compared with data in thermogravic analysis.First, the ASPEN PLUS software was applied to the combustion process simulation and product analysis of four different biomass (ricestraw, wheatstraw, platanewood and larix) and coal in two different metamorphic degrees (bituminous coal, lean coal) and their blending. the simulation showed that the CO generation of the biomass and coal blending was greatly influenced by the temperature, and with temperature increasing the N2 yield gradually reduced, while NOx yield gradually increased; SO2 yield increased, while the SO3 yield decreased. With oxygen concentrations increasing, N2 yield reduced and NOx yield increased gradually, while SO2 yield decreased obviously, and SO3 yield gradually increased.Secondly, the combustion characteristics were analyzed through thermal analysis technique. Along with the increase of biomass blending ratio, the ignition temperature of wheatstraw and ricestraw blending with coal gradually decreased, and that of platanewood and larix blending with coal rose slightly but not obviously; the maximum combustion rate increased, and corresponding combustion temperature decreased; the burnout temperature was reduced, and burnout time was shortened, and the comprehensive combustion characteristics were better. With the increase of oxygen concentrations, the ignition temperature of each biomass and coal blending changed slightly but not obviously, and the maximum combustion rate increased rapidly, and the corresponding temperature also slightly lowered, and the burnout temperature decreased obviously, and burnout time also significantly shortened, and the comprehensive combustion index S increased obviously.Thirdly, the dynamic parameters and oxygen partial pressure index of the biomass and coal blending were calculated through thermal dynamic analysis, it was found that combustion reaction of biomass and coal blending was very complex, in which that of larch and coal blending of combustion reaction was the most complicated. Oxygen concentration change didn't change the reaction mechanism.Finally, experiments in the small fluidized-bed combustion system found that the weight loss of biomass and coal blending mainly occurred within the first minute; whether increasing the biomass ratio or increasing oxygen concentration, the average combustion rate of biomass and coal blending in the first minute increased; Increasing oxygen concentration could greatly decrease the burnout time, which was especially remarkable in low oxygen concentrations. Similar changing rules were found in the main weight loss stage of fluidized combustion of coal blent with biomass and its thermo gravimetric combustion in oxygen-enriched conditions.