Method and system for removing carbon dioxide from exhaust gas by utilizing seawater

Abstract

This invention relates to a method for removing carbon dioxide in an exhaust gas utilizing seawater, and to apparatuses for removing carbon dioxide by the method. The method includes producing a concentrated seawater having an increased concentration of salt by utilizing a reverse osmosis membrane method, producing an ammonia-saturating concentrated seawater by blowing ammonia into the concentrated seawater, contacting a non-heated exhaust gas with the ammonia-saturating concentrated seawater such that carbon dioxide is absorbed in the ammonia-saturating concentrated seawater, collecting a sediment of sodium hydrogen carbonate, and collecting ammonium chloride from a solution comprising the ammonium chloride produced by absorption of the carbon dioxide in the ammonium-saturating concentrated seawater.

1 - 13 . (canceled) 
     
     
         14 . A method for removing carbon dioxide in an exhaust gas utilizing seawater, comprising:
 producing a concentrated seawater having an increased concentration of salt by utilizing a reverse osmosis membrane method at a seawater desalination plant;   producing an ammonia-saturating concentrated seawater by blowing ammonia into the concentrated seawater so as to be saturated;   contacting a non-heated exhaust gas with the ammonia-saturating concentrated seawater such that carbon dioxide in the non-heated exhaust gas is absorbed in the ammonia-saturating concentrated seawater;   collecting a sediment of sodium hydrogen carbonate produced by the absorption of the carbon dioxide in the ammonia-saturating concentrated seawater; and   collecting an ammonium chloride from a solution comprising the ammonium chloride produced by the absorption of the carbon dioxide in the ammonia-saturating concentrated seawater.   
     
     
         15 . The method as set forth in  claim 14 , wherein the collecting of an ammonium chloride is performed by spraying a solution containing the ammonium chloride produced by the absorption of the carbon dioxide in the ammonia-saturating concentrated seawater with a utilization of pressure of the non-heated exhaust gas while cooling the solution by utilizing heat of evaporation of a solvent of the solution so as to settle out. 
     
     
         16 . The method as set forth in  claim 14 , wherein the collecting of an ammonium chloride is performed by heating the solution with a utilization of a heated exhaust gas kept at 100° C. or more so as to chemically decompose the ammonium chloride to produce ammonia. 
     
     
         17 . The method as set forth in  claim 16 , wherein the ammonia produced by the collecting of an ammonium chloride is the ammonia blown into the concentrated seawater to produce the ammonia-saturating concentrated seawater. 
     
     
         18 . The method as set forth in  claim 15 , further comprising:
 cooling moisture vapor produced by the spraying of the solution to collect the moisture vapor as fresh water.   
     
     
         19 . An apparatus for removing carbon dioxide by the method of  claim 15 , the apparatus comprising:
 a carbon dioxide absorbing tank configured to reserve the ammonia-saturated seawater produced by the blowing of ammonia into the concentrated seawater;   a reservoir configured to reserve the solution comprising sodium hydrogen carbonate and ammonium chloride which are produced by the absorption of the carbon dioxide;   a first settling tank configured to spray the solution by utilizing the pressure of the exhaust gas and to cool the solution by utilizing heat of evaporation of the solvent of the solution so as to settle out the sodium hydrogen carbonate; and   a second settling tank configured to spray the solution by utilizing the pressure of the exhaust gas and to cool the solution by utilizing the heat of evaporation of the solvent of the solution so as to settle out the ammonium chloride.   
     
     
         20 . An apparatus for removing carbon dioxide by the method of  claim 16 , the apparatus comprising:
 a carbon dioxide absorbing tank configured to reserve the ammonia-saturated seawater produced by the blowing of ammonia into the concentrated seawater;   a reservoir configured to reserve the solution comprising sodium hydrogen carbonate and ammonium chloride which are produced by the absorption of the carbon dioxide;   an exhaust gas heating tank configured to heat the solution with a heated exhaust gas kept at 100° C. or more so as to chemically decompose the ammonium chloride to produce ammonia; and   a settling tank configured to spray the solution by utilizing the pressure of the exhaust gas and to cool the solution by utilizing the heat of evaporation of the solvent of the solution so as to settle out the ammonium chloride.   
     
     
         21 . The system as set forth in  claim 19 , further comprising:
 a cooling tank configured to cool moisture vapor produced by the spraying of the solution in at least one of the first settling tank and the second settling tank; and   a second reservoir for reserving the cooled moisture vapor.