Method and apparatus for capturing carbon dioxide during combustion of carbon containing fuel

Abstract

A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

What is claimed is: 
     
         1 . A method of processing carbon-based byproducts when burning carbon-containing fuel, the method comprising:
 cooling flue gas discharged from a final boiler in a series of pressurized boilers using boiler feed water to a temperature selected to prevent acid condensation;   filtering the cooled flue gas;   feeding cooling water into a top of a direct contact cooler at a rate selected to promote rate-limiting reactions; and   introducing filtered flue gas through a bottom of the direct contact cooler to remove SO x  and NO x  by conversion to dilute sulfuric and nitric acid.   
     
     
         2 . The method of  claim 1 , wherein the SO x  comprises SO 2 . 
     
     
         3 . The method of  claim 1 , wherein the direct contact cooler cools and condenses moisture from the flue gas in the bottom of the direct contact cooler. 
     
     
         4 . The method of  claim 1 , wherein SO x  and NO x  are removed in the top of the direct contact cooler. 
     
     
         5 . The method of  claim 1 , wherein the direct contact cooler removes almost all of the SO x  and NO x . 
     
     
         6 . The method of  claim 1 , wherein the direct contact cooler also removes mercury present in the flue gas. 
     
     
         7 . The method of  claim 1 , wherein the direct contact cooler is in the form of a single column. 
     
     
         8 . The method of  claim 7 , wherein the single column has a column height selected to promote rate-limiting reactions. 
     
     
         9 . The method of  claim 1 , wherein the direct contact cooler is in the form of multiple columns. 
     
     
         10 . The method of  claim 9 , wherein at least one column of the multiple columns has a column height selected to promote rate-limiting reactions. 
     
     
         11 . The method of  claim 1 , wherein the direct contact cooler simultaneously removes SO x  and NO x  from the filtered flue gas. 
     
     
         12 . The method of  claim 1 , wherein the method further comprises adjusting the acidity of the dilute sulfuric and nitric acid in a neutralizer. 
     
     
         13 . The method of  claim 12 , wherein the method further comprises cooling the dilute sulfuric and nitric acid in a heat exchanger. 
     
     
         14 . The method of  claim 13 , wherein the method regenerates the cooling water.