text: :CaCO ←→ CaO + CO  ΔH = +178 kJ/mol 
  There are two main steps in CaL:
  * Calcination: Solid calcium carbonate is fed into a calciner, where it is heated to 850-950 °C to cause it to thermally decompose into gaseous carbon dioxide and solid calcium oxide (CaO). The almost-pure stream of CO is then removed and purified so that it is suitable for storage or use. This is the forward reaction in the equation above.
  * Carbonation: The solid CaO is removed from the calciner and fed into the carbonator. It is cooled to approximately 650 °C and is brought into contact with a flue gas containing a low to medium concentration of CO. The CaO and CO react to form CaCO, thus reducing the CO concentration in the flue gas to a level suitable for emission to the atmosphere. This is the backward reaction in the equation above.
  Note that carbonation is calcination in reverse.
  Whilst the process can be theoretically performed an infinite number of times, the calcium oxide sorbent degrades as it is cycled. For this reason, it is necessary to remove (purge) some of the sorbent from the system and replace it with fresh sorbent (often in the carbonate form). The size of the purge stream compared with the amount of sorbent going round the cycle affects the process considerably.