Aspen Plus® Process Simulation of Calcium Looping with Different Indirect Calciner Heat Transfer Concepts

Abstract

CO2 reduction has become an urgent need due to the greenhouse effect. Scientists working on the topic agree that the major cause of global warming is greenhouse gases emitted due to human activities. Burning of fossil fuels is one of the main reasons. Using a solid sorbent to capture CO2 at high temperature is a concept which is now being widely considered to reduce CO2 emissions. Capture from flue gas by calcium looping (CaL) may be an attractive alternative due to cheap and readily available sorbent (limestone). CaL may reduce considerably the energy penalty represented by the capture system. A significant transfer of thermal energy is required for the endothermic calcination process. In first generation CaL, the heat is transferred directly by oxy-combustion in the calciner; pure oxygen is then required as the oxidizer to avoid mixing CO2 with N2, and the energy required to produce oxygen gives an unwanted energy penalty. CaL technology would be an even more attractive alternative for the thermal power industry if the heat could be transferred indirectly to the calciner. By high-temperature integration between the CO2 capture plant and the power plant, the energy penalty associated with oxy-combustion would be avoided. In this work, Aspen Plus® is used to simulate the CaL process with indirect heat transfer applying different indirect heat transfer concepts. Six different cases are studied and the results are discussed. It has confirmed such a scheme could give an energy penalty lower than for example amine scrubbing or oxy-combustion.