Purification of carbon dioxide

Apparatus for removing a first contaminant selected from oxygen and carbon monoxide from impure liquid carbon dioxide, said apparatus comprising:

• a mass transfer separation column system for separating impure liquid carbon dioxide to produce first contaminant-enriched overhead vapor and carbon dioxide-enriched bottoms liquid;
• a reboiler for re-boiling carbon dioxide-enriched bottoms liquid by indirect heat exchange against crude carbon dioxide fluid to produce carbon dioxide-enriched vapor for said column system and cooled crude carbon dioxide fluid;
• a heat exchanger for further cooling cooled crude carbon dioxide fluid by indirect heat exchange to produce partially condensed crude carbon dioxide fluid;
• a conduit arrangement for feeding cooled crude carbon dioxide fluid from said reboiler to said heat exchanger;
• a phase separator for phase separating said partially condensed crude carbon dioxide fluid to produce said impure liquid carbon dioxide and carbon dioxide-depleted vapor;
• a conduit arrangement for feeding partially condensed crude carbon dioxide fluid from said heat exchanger to said phase separator;
• a first pressure reduction arrangement for reducing the pressure of impure liquid carbon dioxide to produce reduced pressure impure liquid carbon dioxide;
• a conduit arrangement for feeding impure liquid carbon dioxide from said phase separator to said first pressure reduction arrangement;
• and
• a conduit arrangement for feeding reduced pressure impure liquid carbon dioxide from said first pressure reduction arrangement to said column system.