Study On The Combustion Performance Of Coal Chemical Chain Of Modified Dolomite Iron Ore Concentrate Oxygenate Carrier

Chemical Looping Combustion（CLC）is one of the mainstream CO₂capture methods,which uses the lattice oxygen in the oxygen carrier to provide oxygen for combustion and divides the traditional combustion process into two parts.capture.Oxygen carriers are the key,and iron-based oxygen carriers are used in large quantities for the preparation of oxygen carriers because of their low cost and easy availability,superior environmental friendliness,and good oxygen transfer capability and stability under atmospheric pressure and high temperature conditions.In this thesis,we used Baiyun Ebo iron ore concentrate located in Baotou City,which contains a large amount of iron and a small amount of cerium and other common catalyst active elements,as the object of study,and used the in situ reduction method to prepare Al/ore ratio but doped with different ratios of Mn O₂/Mg O modified iron ore carriers to investigate the feasibility of their use in coal chemical chain combustion.First,based on the ascending thermogravimetric experiments,it was found that the appropriate reaction temperature is particularly important for chemical chain combustion,and in the thermogravimetric experiments,it was determined that the reactions are mainly concentrated in the interval of 850°C-950°C.Subsequently,the optimal temperature of the oxygen carrier was further determined in this temperature band.It was found that the carbon conversion at 850°C was 45.22%,which grew to 66.08%at 950°C.The cyclic conversion of the oxygenate carriers was decreasing during the 10reduction-oxidation cycle experiments at 950°C.Further,the modification was investigated to enhance the reaction activity.The experimental results showed that the oxygen carrier prepared by adding a small amount of Mn O2 to the iron ore concentrate and then performing aluminothermal in situ reduction significantly enhanced the reduction of iron ore concentrate,and the best reaction performance of the oxygen carrier with coal was achieved at 15 wt%of Mn O₂addition,and the carbon conversion rate of its single reduction experiment at 950°C was84.13%which was 28%higher than that of the original ore,and the CO₂purity was90.78%which was 10%higher than that of the original ore.It was 10%higher than the original ore.After 10 cycles,the carbon capture rate was finally maintained at about 80%after a decreasing process,which indicates that the presence of Mn O₂can increase the reaction activity and improve the stability of the oxygen carrier cycle.After a long redox cycle,the staggered distribution of most elements（i.e.Al,Mg and Fe）was promoted,which enhanced the interaction between Mn and Fe oxides and facilitated the high activity and stability of the oxygen carrier in the continuous chemical cycle combustion process.Finally,the modified oxygen carriers were prepared by adding a small amount of Mg O to the original iron concentrate oxygen carriers and then subjected to aluminothermic in situ reduction,and their effects on the reactivity of the modified oxygen carriers with and lignite were investigated.The results showed that the addition of the inert component Mg O improved the reactivity of the iron ore oxygen carriers to a certain extent,but the enhancement of the activity was relatively small compared with that of Mn O₂.However,the addition of Mg O made the oxygen carrier show good stability at high temperature and the best reaction temperature changed to 900°C compared with the original and Mn-modified iron ore concentrate,and the carbon conversion rate of the oxygen carrier was found to be stable at about 70%with the addition of Mg O for 10 cycles.