▁suitable ▁for ▁se quest r ation , ▁and ▁the ▁spent ▁Ca O ▁has ▁potential ▁uses ▁elsewhere , ▁most ▁not ably ▁in ▁the ▁c ement ▁industry . ▁ ▁The ▁heat ▁necessary ▁for ▁calc ination ▁can ▁be ▁provided ▁by ▁o xy - comb ust ion ▁of ▁coal ▁below . ▁ ▁O xy - comb ust ion ▁of ▁coal : ▁P ure ▁o xygen ▁rather ▁than ▁air ▁is ▁used ▁for ▁comb ust ion , ▁elimin ating ▁the ▁large ▁amount ▁of ▁nit ro gen ▁in ▁the ▁fl ue - gas ▁stream . ▁After ▁partic ulate ▁matter ▁is ▁removed , ▁fl ue ▁gas ▁consists ▁only ▁of ▁water ▁v apor ▁and ▁CO 2 , ▁plus ▁smaller ▁amounts ▁of ▁other ▁poll ut ants . ▁After ▁compression ▁of ▁the ▁fl ue ▁gas ▁to ▁remove ▁water ▁v apor ▁and ▁additional ▁removal ▁of ▁air ▁poll ut ants , ▁a ▁nearly ▁pure ▁CO 2 ▁stream ▁suitable ▁for ▁storage ▁is ▁produced . ▁ ▁The ▁carbon ator ' s ▁operating ▁temperature ▁of ▁ 6 5 0 - 7 0 0 ▁o C ▁is ▁chosen ▁as ▁a ▁comprom ise ▁between ▁higher ▁equilibrium ▁( maxim um ) ▁capture ▁at ▁lower ▁temper atures ▁due ▁to ▁the ▁ex oth erm ic ▁nature ▁of ▁the ▁carbon ation ▁step , ▁and ▁a ▁decre ased ▁reaction ▁rate . ▁Similarly , ▁the ▁temperature ▁of ▁> 8 5 0 ▁o C ▁in ▁the ▁cal cin ator ▁strik es ▁a ▁balance ▁between ▁increased ▁rate ▁of ▁calc ination ▁at ▁higher ▁temper atures ▁and ▁reduced ▁rate ▁of ▁de grad ation ▁of ▁Ca O ▁sor b ent ▁at ▁lower