Methods and systems for reducing carbon dioxide emissions

Abstract

A reduced emission kiln is described. In some embodiments, the kiln includes a combustion zone for generating heat energy. The combustion zone includes an oxygen inlet and a fuel inlet. In some embodiments, the kiln also includes a calcination zone for converting limestone into lime and carbon dioxide in response to the heat energy from the combustion zone. The calcination zone includes an inlet for limestone, a conduit for directing the carbon dioxide to the combustion zone for use as a flood gas to control the heat energy, an outlet for directing the lime to a hydration chamber, and a carbon dioxide permeable membrane for separating the carbon dioxide in the calcination zone from other materials in the calcination zone and preventing the other materials from entering the conduit for directing the carbon dioxide.

What is claimed is:  
     
         1 . A reduced emission kiln, said kiln comprising:
 a combustion zone for generating a heat energy, said combustion zone including an oxygen inlet and a fuel inlet; and   a calcination zone for converting limestone into lime and carbon dioxide in response to said heat energy from said combustion zone, said calcination zone including an inlet for limestone, a conduit for directing the carbon dioxide to said combustion zone for use as a flood gas to control said heat energy, an outlet for directing the lime to a hydration chamber, and a carbon dioxide permeable membrane for separating the carbon dioxide in said calcination zone from other materials in said calcination zone and preventing the other materials from entering said conduit for directing the carbon dioxide.   
     
     
         2 . The kiln according to  claim 1 , further comprising a hydration chamber for hydrating the lime received from said outlet for directing the lime, wherein the lime is converted to slaked lime in said hydration chamber. 
     
     
         3 . The kiln according to  claim 1 , further comprising means for capturing the carbon dioxide present in said calcination zone. 
     
     
         4 . The kiln according to  claim 1 , further comprising a gasification zone for gasifying fuels to be combusted in said combustion zone, said gasification zone including a fuel inlet and a conduit for directing the gasified fuels to said combustion zone. 
     
     
         5 . The kiln according to  claim 1 , further comprising a preheating zone for preheating limestone, said preheating zone including a conduit for directing preheated limestone to said calcination zone. 
     
     
         6 . The kiln according to  claim 5 , further comprising a conduit for directing said heat energy from said combustion zone to said preheating zone. 
     
     
         7 . The kiln according to  claim 1 , wherein a carbonaceous fuel is combusted in said combustion zone. 
     
     
         8 . A method of reducing emissions from a kiln, said method comprising:
 providing a carbonaceous fuel and oxygen;   combusting said carbonaceous fuel and oxygen to form a gaseous mixture including carbon dioxide, said gaseous mixture providing a heat energy;   providing limestone;   mixing said gaseous mixture with said limestone thereby heating said limestone with said heat energy;   converting said limestone to lime and carbon dioxide;   separating carbon dioxide from said lime and from other materials in said gaseous mixture; and   mixing at least a portion of the carbon dioxide separated from said lime and from other materials in said gaseous mixture with said carbonaceous fuel and oxygen while combusting said carbonaceous fuel and oxygen thereby controlling said heat energy.   
     
     
         9 . The method according to  claim 8 , further comprising:
 hydrating said lime.   
     
     
         10 . The method according to  claim 8 , further comprising:
 capturing at least a portion of said carbon dioxide separated from said lime and from other materials in said gaseous mixture.   
     
     
         11 . The method according to  claim 8 , further comprising:
 gasifying said carbonaceous fuel prior to combusting.   
     
     
         12 . The method according to  claim 8 , further comprising:
 preheating limestone prior to converting.   
     
     
         13 . The method according to  claim 12 , further comprising:
 preheating limestone with said heat energy.   
     
     
         14 . A reduced emission combustion system, said system comprising:
 a boiler including a combustion zone for combusting carbonaceous fuels to form a gaseous mixture, said gaseous mixture providing a heat energy;   a particle separator for removing fly ash and other particulates from said gaseous mixture;   a calcium-based heat exchanger configured to mix and heat steam and slaked lime to form lime and steam, configured to capture the exothermic heat of reaction when the lime reacts to form slaked lime, and configured to recycle the slaked lime to the beginning of said calcium-based heat exchange system, said calcium-based heat exchange system including means for collecting dissolved slaked lime;   a dry or wet scrubber for removing contaminants present in said gaseous mixture, said dry or wet scrubber including means for utilizing said dissolved slaked lime from said calcium-based heat exchange system;   a carbon dioxide removal chamber for removing carbon dioxide present in said gaseous mixture, said carbon dioxide removal chamber including means for bringing said gaseous mixture into contact with lime or slaked lime to generate limestone; and   a sorbent regenerator for generating lime and carbon dioxide from said limestone generated in said carbon dioxide removal chamber, said sorbent regenerator including means for providing said lime generated to said carbon dioxide removal chamber.   
     
     
         15 . The system according to  claim 14 , wherein said sorbent regenerator is a low emission kiln comprising:
 a combustion zone for generating a heat energy, said combustion zone including an oxygen inlet and a fuel inlet; and   a calcination zone for converting limestone into lime and carbon dioxide in response to said heat energy from said combustion zone, said calcination zone including an inlet for limestone, a conduit for directing the carbon dioxide to said combustion zone for use as a flood gas to control said heat energy, an outlet for directing the lime to a hydration chamber, and a carbon dioxide permeable membrane for separating the carbon dioxide in said calcination zone from other materials in said calcination zone and preventing the other materials from entering said conduit for directing the carbon dioxide.   
     
     
         16 . The system according to  claim 15 , further comprising:
 a heat exchanger for capturing heat from said calcination zone.   
     
     
         17 . The system according to  claim 15 , further comprising:
 a heat exchanger for capturing heat from said combustion zone.   
     
     
         18 . The system according to  claim 15 , further comprising:
 means for feeding lime generated in said calcination zone to said combustion zone.   
     
     
         19 . The system according to  claim 14 , further comprising means for generating electricity. 
     
     
         20 . The system according to  claim 19 , wherein said means for generating electricity include a turbine system.