Apparatus and process for removing carbon dioxide from combustion exhaust gas

An apparatus for removing CO.sub.2 from a combustion exhaust gas by contacting said exhaust gas with an absorbent containing an aqueous solution of an alkanolamine, comprising:

• a tower having a lower end part and an upper end part;
• an exhaust gas inlet in said lower end part of said tower and a treated gas outlet in said upper end part of said tower;
• a first contact section in said tower above said lower end part for the flow of exhaust gas from said exhaust gas inlet upwardly therethrough;
• means for introducing an aqueous alkanolamine solution into said tower above said first contact section for the flow of aqueous alkanolamine solution through said first contact section in counterflow contacting relationship with said combustion exhaust gas passing through said first contact section for removal of CO.sub.2 from said combustion exhaust gas in said first contact section;
• cooling means upstream of said exhaust gas inlet with respect to combustion exhaust gas flow for cooling said combustion exhaust gas and condensing water therefrom to provide condensate from said exhaust gas of CO.sub.2 therefrom in said first prior to flow of said exhaust gas to said exhaust gas inlet;
• a second contact section between said means for introducing said aqueous solution and said treated gas outlet for producing counterflow contacting engagement in said second contact section of said condensate produced by said cooling means with said combustion exhaust gas after removal of CO.sub.2 therefrom in said first contact section;
• a water supply section disposed above and downstream of said second contact section in said tower for supplying water in counterflow contacting relationship with said combustion exhaust gas in said second contact section;
• and
• means for supplying said condensate produced by said cooling means to said water supply section to provide said water therefor.