Oxy-fuel cracking boilers using co2 as the working fluid

Abstract

Disclosed is a boiler may that uses recycled carbon dioxide as a working fluid. Instead of releasing high-purity CO 2 into the atmosphere, the bulk of the CO 2 is utilized as the working fluid and the produced CO 2 is captured and sent to a pipeline for utilization or storage. These systems will minimize heat loss and achieve essentially zero CO 2 emission to the air.

What is claimed is: 
     
         1 . A method for heat treating hydrocarbons, comprising:
 providing a hydrocarbon fuel source mixed with an oxidant source and carbon dioxide gas to a boiler, wherein the hydrocarbon fuel source is burned in the boiler to produce a heated outlet gas comprising carbon dioxide and water;   separating the water from the carbon dioxide in the heated outlet gas; and   recycling at least a portion of the separated carbon dioxide back to the boiler.   
     
     
         2 . The method of  claim 1 , wherein the hydrocarbon fuel source includes natural gas. 
     
     
         3 . The method of  claim 1 , further comprising heating the recycled portion of the separated carbon dioxide stream with heat from the heated outlet gas exiting the boiler. 
     
     
         4 . The method of  claim 1 , further comprising heating at least a portion of the oxidant source with heat from the heated outlet gas exiting the boiler. 
     
     
         5 . The method of  claim 1 , further comprising providing the water separated from the water/carbon dioxide stream back to the boiler, and heating the water with heat generated in the boiler to produce high pressure steam. 
     
     
         6 . The method of  claim 1 , further comprising superheating the high pressure steam with heat from the heated outlet gas exiting the boiler. 
     
     
         7 . The method of  claim 1 , wherein the water is separated from the carbon dioxide in one or more mol sieve beds. 
     
     
         8 . The method of  claim 7 , further comprising heating the mol sieve beds with at least some of the recycled carbon dioxide. 
     
     
         9 . The method of  claim 7 , wherein the one or more mol sieve beds includes two mol sieve beds. 
     
     
         10 . The method of  claim 7 , wherein the one or more mol sieve beds adsorb water at 125° C. 
     
     
         11 . The method of  claim 1 , further comprising superheating and cooling the heated outlet gas before separation. 
     
     
         12 . The method of  claim 1 , further comprising pressurizing the recycle carbon dioxide before providing to the boiler.