Numerical Calculation And Experimental Study On The Oxygen Release Performance Of Iron-based Oxygen Carriers During Tar Pyrolysis

Chemical looping technology is a new type and highly efficient utilization technology.Oxygen carrier(OC)as a medium to convert a single reaction into two or more secondary reactions can effectively reduce the entropy change and improve energy efficiency.Based on the chemical looping technology,Research group proposed a new technology for the yield of carbon black(CB)from coal tar pyrolysis.After previous research,it was found that iron-based oxygen carriers have good reaction performance in the process of coal tar pyrolysis to manufacture CB and can promotes coal tar pyrolysis and carbon chain formation,thus achieves the purpose of efficient CB production.However,the reaction rules and the formation mechanism of CB are not yet clear.In this paper,further exploration and optimization are carried out for the manufacture of carbon black from coal tar pyrolysis.The main research contents and results are as follows:Firstly,TG/FTIR/GCMS technology was used to analyze the coal tar pyrolysis process and pyrolysis stages for the research object,and the catalysis of the oxygen carrier in the chemical looping pyrolysis process was studied to explore the differences.The pyrolysis products and principle of coal tar under temperature were studied,and the activation energies at different reaction stages were studied based on the Arrhenius formula.Secondly,Utilize Material Studio to simulate the side reactions that may occur during the carbon black pyrolysis of tar and the evolution of carbon black aggregates were simulated.According to the simulation results,based on Gibbs' principle of minimization of free energy,the interaction between main response and other competing reactions(secondary reactions)in the process was analyzed.The variation of Gibbs free energy and the reaction equilibrium constants before and after each competitive reaction are calculated.Theoretically,the feasibility of using iron-based oxygen carriers and incomplete combustion of coal tar to make carbon black is demonstrated,and it has low NOx emission.The characteristics of the competitive reactions are simulated and compared with each other.The molecular evolution and the thermogravimetry experiments are used to study the evolution of aggregates.Combining molecular modeling and thermogravimetry experiments to study the evolution process of aggregates,the formation mechanism of carbon black from CLP was analyzed.In addition,the TG-MS method was applied on the competition reaction.Mainly for the solid-solid reaction and gas-solid reaction,the initial temperature of each reaction and the corresponding temperature when the reaction rate is maximum are determined.Through the corresponding relationship between the mass spectrometry ion concentration and the gas concentration,the reactivity of the gas and the oxygen carrier is quantitatively analyzed.The consumption of carbon black was calculated from the area integral of the mass spectrometer curve.The SEM-EDS was used to characterize the gas-solid reaction product and the solid reaction product.The competition reaction mechanism was studied from the experimental point of view,and it was used for the pyrolysis experiment of the coal tar chemical chain in the fluidized bed.Finally,the Fe/Al OC was prepared by impregnation method,and the thermogravimetry of the reaction performance and cycle performance was studied.The oxidation and reduction performance of many cycles was excellent,and the regeneration rate of cycled oxygen carrier was up to 96%.The cold fluidization test and the coal tar pyrolysis experiment were carried out in a fluidized bed facility designed and established.Using the pressure sensor and data acquisition module,the characteristics of air distributor,bed fluidization,bed body were researched.The overall pressure drop characteristics provide support for coal tar pyrolysis experiments.Based on the above,Fe/Al OC was used for the cracking experiment.The components of the flue gas were detected by flue gas analyzer and gas chromatography to calculate the carbon black yield,energy utilization,and cyclone separator efficiency.This paper combined simulation and experiment to study the coal tar competition mechanism,and uses the thermogravimetric analysis method and fluidized bed experiment to explain the coal tar pyrolysis mechanism,optimize the experimental conditions,further improve the carbon black yield,reduce pollutant emissions.