Study On Chemical Effects Of CO₂ Gasification Reaction On Coal Char Oxyfuel Combustion

As one of greenhouse gas carbon dioxide low-emission technologies,the oxyfuel technology has quickly developed around the world.However,in the oxy-char burning process,a further investigation is needed to the interaction essence between carbon dioxide gasification and oxygen oxidation to carbon.In this thisis,an oxy-fuel combustion experiment system was built in present work,which has features of high temperature rate,on-line mass measurement,continue multi-gas input,et al.Coal char reaction rate,burn out time and the contribution ratio of gasification reaction of CO2 was obtained through experiments.An experiment of CO2 gasification reaction with char was made.The experiment results showed that carbon consumption rate changes with reaction temperature and CO2 partial pressure.At 1150? the reaction time of 95%partial pressure case was 0.377 times of 73%partial pressure case.A reatively high temperature and partial preasure had a promoting effect on the gasification reaction between CO2 and coal char.The contribution ratio of gasification reaction by CO2 and oxidation reaction by O2 with coal char to carbon conversion was reasarched in experiment.At a relatively high reaction temperature,CO2 had a promoting effent on char oxy-fuel combustion,while a lower temperature inhibiting effect.At 1200?,27%O2/73%CO2 reaction gas,the contribution ratio of gasification reaction of CO2 to maximum carbon conversion rate was 36.3%.Oxy-fuel combustion had a promoting effect on carbon consumption rate comparing with air combustion at this temperature.At a temperature above coal ash FT,the burning performance of coal char was very different from non-melting combustion.A melten state prolonged the combustion time of char as a small porosity.Gasification reaction between CO2 and coal char reducing char temperature and multing ratio thus can promote carbon consumption.A Weighted Exponential Sum Kinetic Model(WESM)was built in present work.The model had a well performance in carbon conversion rate and burn-out time predicton comparing with other three typical models.The prediction accuracy was improved using WESM model.