Simulation Of Chemical Chain Combustion System Based On Aspen Plus

Reducing the concentration of CO₂ in the atmosphere through CO₂ capture and storage is an effective way to slow down the global Greenhouse Effect.Traditional fuel combustion is the combustion of fuel directly contacting with air,and chemical-chain-burning?CLC?is a new way of carbon capture.The oxygen carrier is recycled in two reactors,not only to separate the oxygen in the air,but also to transfer the separated oxygen to the fuel for the flameless combustion of the fuel.Because the chemical chain combustion technology can reduce the cost of CO₂ recovery,it plays an important role in solving the energy and environmental problems of innovation.At the same time,the chemical chain combustion technology through the cascade use of energy,energy utilization rate is high.In this paper,the preparation method,compressive strength and sintering temperature of oxygen carrier were introduced,and the melting point,oxygen loading rate and the highest oxidation reaction temperature of different oxygen carriers were compared in order to study the selection of oxygen carriers.Fe,Ni,Cu,Mn,Co oxygen carriers were selected as the research object,and then the thermodynamic analysis of the oxygen carriers was carried out in detail,including enthalpy change,entropy change,Gibbs free energy and chemical equilibrium constant,and the relationship between the thermodynamic parameters and temperature was obtained.Three kinds of oxygen carriers with good performance were selected:Fe₂O₃/Al₂O₃?NiO/NiAl₂O₄?CuO/CuAl₂O₄.Through the analysis of each unit in the chemical chain combustion system,using Aspen Plus simulation software,the numerical simulation of the selected oxygen carrier in the chemical chain combustion of gas is carried out.The chemical reaction mechanism of the oxygen carrier in the fuel reactor is introduced in detail.By adjusting the enthalpy,entropy and Gibbs free energy of each substance at different temperatures in the software,The effects of temperature,pressure,the mole ratio of oxygen carrier to CH₄,and the mole ratio of air to methane on the flue gas composition at the outlet of the fuel reactor and the air reactor were analyzed.The minimum air quantity and the minimum mass flow rate of oxygen carrier are calculated to meet the requirements of fuel combustion,and the optimum operating parameters for the system to achieve the maximum CO₂ capture rate are found.By comparing the difference between the direct contact combustion of air and methane and the chemical chain combustion,the advantages of the chemical chain combustion are obtained,and the advantages and disadvantages of the three oxygen carriers are further compared.Finally,the best oxygen carrier Fe₂O₃/Al₂O₃ is obtained.In addition,the Aspen Plus software was used to simulate the chemical chain combustion of coal combustion with Fe₂O₃/Al₂O₃ as the carrier oxygen.The effects of temperature,pressure and oxygen carrier fuel ratio on the flue gas composition and oxygen carrier content at the outlet of fuel reactor and air reactor were studied,and the optimal operating parameters were found out.Finally,the differences of outlet flue gas,C capture rate and minimum mass flow rate of oxygen carrier in the reactor were compared under the same oxygen carrier Fe₂O₃/Al₂O₃.