Numerical Study On Gas-Solid Two Phase Flow And Magnetic Separation In The Chemical Looping Reduction Reactor

Chemical looping combustion use the oxygen carrier to divide the traditonal fuel-air contact reaction into two processes.Firstly,the oxygen carrier is oxidized in air,then reduced in the gas.Chemical looping combustion has the advantages of CO2 separation without energy consumption,no NOx generation,and reducing the exergy loss.It has been shown that the presence of a large number of bubbles in the reduction reactor can lead to the uneven contact between the oxygen carrier(weakly magnetic Fe2O3)and the gas,and a decrease in burner efficiency.In addition,the effective way of improving the combustion efficiency is how to separate the deoxidized oxygen carrier(ferromagnetic Fe3O4)from the reduction reactor.Therefore,increasing the uniformity of the solid distribution in the reduction reactor and separating the deoxidized oxygen carrier after the reaction is the focus of this article.In this paper,the numerical simulation method is to study the flow of oxygen carrier and deoxidized oxygen carrier in the chemical reactor with the support of gas,And designing a rotating magnetic field separation device to investigate the separation effect of the deoxidized oxygen carrier from the reduction reactor into the air reactor with the help of a magnetic field.First of all,Euler-Euler method was used to study the flow of two-component particles in the reduction reactor without feed tube and the flow of two-component particles in the reduction reactor with feed tube by changing the perforated rate,gas velocity,concentration ratio.In addition,rotating magnetic field is used again to enable the deoxidized oxygen carrier enter the air reactor from the reduction reactor,which lead to improve the system efficiency of the chemical looping combustion.Analysis of single-component particles in a chemical reduction reactor without a feed tube yields:(1)As the perforated rate in the air distribution plate increases,the fluidization efficiency of the particles increases,however,an excessively large perforated rate will result in an excessively large ratio of gas and solid,which will reduce the reaction efficiency.Therefore,the optimal number of openings is 7;(2)The increase of the gas flow rate results in the increase of the spatial distribution range of the oxygen carrier in the reactor,thus reducing the concentration of the oxygen carrier,and reducing the reduction efficiency.Therefore,the optimal gas velocity is 0.52m/s.Analysis of two-component particles in a chemical reduction reactor with a feed tube yields:(3)it was found that as the concentration ratio increases,the concentration distribution of the oxygen carrier in the reactor increases linearly,and the spatial distribution is more uniform.Therefore,when the concentration ratio is 2:1,the contact efficiency between the oxygen carrier and the gas is optimized.Under the premise of the same two-component concentration ratio,increasing the air velocity will result in a significant non-uniform of radial concentration distribution of the oxygen carrier particles.In addition,the difference in density between the oxygen carrier and the deoxidized oxygen carrier causes the deoxidized oxygen carrier in the reduction reactor to flow back to the air reactor,which is an important factor contributing to the above results.Finally,Maxwell commercial software was used to simulate the magnetic flux density distribution in the reduction reactor.the calculated magnetic field force were introduced into the momentum source,and it is found that the distribution of the deoxidized oxygen carrier is more uniform in the reduction reactor without magnetic field,However,there are a part of the deoxidized oxygen carriers in the reduction reactor with magnetic field.It is indicated that the magnetic field contribute to improve separation efficiency.Compared with that without magnetic field,the separation efficiency of the deoxidized oxygen carrier increased by 21.8%from 2.8s to 3.0s in the reduction reactor with magnetic field.Tn the paper,the research production find the operating parameters about achieving uniform distribution of the oxygen carrier in the reduction reactor,and the use of rotating magnetic field achieves that the deoxidized oxygen carrier separated rapidly from the reduction reactor,It has an obvious scientific significance that improve the system efficiency of chemical looping combustion.