Aspen Plus simulations of fluidised beds for chemical looping combustion

• Aspen Plus is applied to chemical looping combustion.
• The bubbling bed and the circulating bed are modelled using appropriate combinations of ideal reactors.
• The effect of the shrinking-core model for the non-catalytic heterogeneous reactions is investigated.
• The methodology is checked against experimental data from the literature.

Chemical Looping Combustion (CLC) is a technology able to generate energy whilst managing CO2 emissions. A system composed by two interconnected fluidised beds is often used in CLC: the two fluidised beds are employed for carrying out the oxidation and reduction reactions of the metal oxide employed as oxygen carrier. In this work, a model to implement fluidised bed systems in Aspen Plus is presented. Depending on the hydrodynamic regimes, two different models are considered: one of the two fluidised beds, called the fuel reactor, is modelled according to the two-phase theory (i.e. emulsion and bubble phase) whilst the other bed, called the air reactor, is assumed to operate in the fast fluidisation regime. Kinetic equations for heterogeneous gas/solid reactions are also considered in the model. Simulation tests for each fluidised bed are carried out, and comparisons are made with experimental data from the literature. A comparison with the largely used Gibbs reactor model is carried out showing the advantages of using the models developed here. In addition, the net heat duty of the whole process is calculated and the role of the main variables that affect the process is investigated.