Modelling the continuous calcination of CaCO3 in a Ca-looping system

Abstract

The Ca-Looping (CaL) process for CO2 post-combustion capture is a promising technology that has received lot of attention concerning both experimental and modelling aspects in recent years. In this work, a calciner reactor model based on simple fluid-dynamic assumptions and including calcination kinetics is proposed. The main objective of the reactor model is to evaluate the CaCO3 content leaving the calciner or, in other words, the calciner efficiency defined as the fraction of CaCO3 calcined in the reactor, as a function of calciner operating conditions such as solid inventory, calciner temperature, solid circulation rate or fresh sorbent make-up flow. Different analysis have been carried out to determine a feasible operating window of the reactor where high calciner efficiencies are achieved at relatively low temperatures and reasonable solid residence times in the calciner. The results obtained show that typical solid inventories in a range of 8000–12,000mol of Ca/m2 and temperatures of 1173–1183K, will result into such calciner efficiencies well over 95%. These results reinforce the CaL system application at a large scale for CO2 capture and make the model as a valuable tool for interpreting future experimental results obtained from pilot-scale CaL facilities.