Apparatus and method for recovering energy after carbon dioxide capture

Abstract

Disclosed are an apparatus and a method for recovering energy after carbon dioxide capture. The apparatus includes an energy recovery unit at a discharge part of a carbon dioxide capturing apparatus through which captured carbon dioxide is discharged. The energy recovery unit reduces a discharge pressure of the carbon dioxide to a pressure level suitable for a fixation or conversion treatment, and simultaneously generates and recovers energy generated during the pressure reduction.

What is claimed is: 
     
         1 . An apparatus for recovering energy after carbon dioxide capture, comprising an energy recovery unit at a discharge part of a carbon dioxide capturing apparatus, the discharge part configured for discharging captured carbon dioxide, wherein the energy recovery unit reduces a discharge pressure of the carbon dioxide and simultaneously recovers energy generated during the pressure reduction. 
     
     
         2 . The apparatus of  claim 1 , wherein the discharge pressure is reduced to a pressure suitable for a fixation or conversion treatment of the captured carbon dioxide. 
     
     
         3 . The apparatus of  claim 1 , wherein the energy recovery unit is connected to one or more process operating units of the carbon dioxide capturing apparatus and is configured and arranged to supply the recovered energy to one or more of the process operating units. 
     
     
         4 . The apparatus of  claim 1 , wherein the apparatus further comprises a condenser at the discharge part, and the energy recovery unit comprises:
 a turbine disposed at an outlet of the condenser; and   a generator connected to the turbine.   
     
     
         5 . A method for recovering energy after carbon dioxide capture, comprising:
 capturing, by a carbon dioxide capturing apparatus, carbon dioxide from an exhaust gas;   discharging, by the carbon dioxide capturing apparatus, the captured carbon dioxide, the discharged carbon dioxide having a discharge pressure;   reducing the discharge pressure of the discharged carbon dioxide to a pressure level suitable for a fixation or conversion treatment; and   recovering energy generated during the pressure reduction.   
     
     
         6 . The method of  claim 5 , further comprising supplying the recovered energy to one or more process operating units of the carbon dioxide capturing apparatus. 
     
     
         7 . The method of  claim 5 , wherein the step of recovering energy comprises:
 flowing discharged carbon dioxide through a turbine, thereby rotating the turbine with the discharge pressure of the discharged carbon dioxide to create a rotary force;   reducing the pressure of the carbon dioxide that has flowed through the turbine to a reduced pressure level suitable for the fixation or conversion treatment; and   delivering the rotary force of the turbine to a generator connected to the turbine and allowing generation of energy in the generator.   
     
     
         8 . The method of  claim 7 , wherein when the discharge pressure of the carbon dioxide captured by the carbon dioxide capturing apparatus ranges from about 1.8 atm to about 6 atm, the reduced pressure of the carbon dioxide is less than about 1.8 atm. 
     
     
         9 . The method of  claim 8 , wherein the reduced pressure of the carbon dioxide is less than about 1.6 atm. 
     
     
         10 . The method of  claim 8 , wherein the reduced pressure of the carbon dioxide is less than about 1.4 atm. 
     
     
         11 . The method of  claim 8 , wherein the reduced pressure of the carbon dioxide is about 1.2 atm.