▁temper atures . ▁ ▁Process ▁description ▁▁ ▁Ca L ▁is ▁usually ▁designed ▁using ▁a ▁dual ▁fluid ised ▁bed ▁system ▁to ▁ensure ▁sufficient ▁contact ▁between ▁the ▁gas ▁streams ▁and ▁the ▁sor b ent . ▁The ▁calc iner ▁and ▁carbon ator ▁are ▁fluid ised ▁b eds ▁with ▁associated ▁process ▁equipment ▁for ▁separ ating ▁the ▁g ases ▁and ▁sol ids ▁attached ▁( such ▁as ▁cycl ones ). ▁Cal c ination ▁is ▁an ▁end oth erm ic ▁process ▁and ▁as ▁such ▁requires ▁the ▁application ▁of ▁heat ▁to ▁the ▁calc iner . ▁The ▁opposite ▁reaction , ▁carbon ation , ▁is ▁ex oth erm ic ▁and ▁heat ▁must ▁be ▁removed . ▁Since ▁the ▁ex oth erm ic ▁reaction ▁happens ▁at ▁about ▁ 6 5 0   ° C ▁and ▁the ▁end oth erm ic ▁reaction ▁at ▁ 8 5 0 - 9 5 0   ° C , ▁the ▁heat ▁from ▁the ▁carbon ator ▁cannot ▁be ▁directly ▁used ▁to ▁heat ▁the ▁calc iner . ▁ ▁The ▁fluid isation ▁of ▁the ▁solid ▁bed ▁in ▁the ▁carbon ator ▁is ▁achieved ▁by ▁passing ▁the ▁fl ue ▁gas ▁through ▁the ▁bed . ▁In ▁the ▁calc iner , ▁some ▁of ▁the ▁recovered ▁CO 2 ▁is ▁rec yc led ▁through ▁the ▁system . ▁Some ▁o xygen ▁may ▁also ▁be ▁passed ▁through ▁the ▁re actor ▁if ▁fuel ▁is ▁being ▁burn ed ▁in ▁the ▁calc iner ▁to ▁provide ▁energy . ▁ ▁Pro vision ▁of ▁energy ▁to ▁the ▁calc iner ▁▁ ▁He at ▁can ▁be ▁provided ▁for ▁the ▁end oth erm ic ▁calc ination ▁step ▁either ▁directly ▁or