text: CaL is usually designed using a dual fluidised bed system to ensure sufficient contact between the gas streams and the sorbent. The calciner and carbonator are fluidised beds with associated process equipment for separating the gases and solids attached (such as cyclones). Calcination is an endothermic process and as such requires the application of heat to the calciner. The opposite reaction, carbonation, is exothermic and heat must be removed. Since the exothermic reaction happens at about 650 °C and the endothermic reaction at 850-950 °C, the heat from the carbonator cannot be directly used to heat the calciner.
  The fluidisation of the solid bed in the carbonator is achieved by passing the flue gas through the bed. In the calciner, some of the recovered CO is recycled through the system. Some oxygen may also be passed through the reactor if fuel is being burned in the calciner to provide energy.