Method and device for feeding back exhaust gas from a gas turbine with a downstream waste heat boiler

Abstract

A method for feeding back exhaust gas from a gas turbine with a downstream waste heat boiler, wherein this exhaust gas is metered into the air inflow stream of a gas turbine, with the result that the temperature and the composition of the exhaust gas can be controlled, and in this way highly concentrated carbon dioxide (CO 2 ) is obtained which can be injected into a storage facility, so that the balance of the carbon dioxide for the entire process can be kept low or is negligible. The temperature in the gas turbine can be lowered and the proportion of carbon dioxide in the exhaust gas can be considerably increased. After combustion has taken place and heat has been exchanged, gas washing is possible, carbon dioxide can be recovered and, the proportion of free oxygen in the exhaust gas can be lowered.

1 . A process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine, in which a fuel gas suitable for combustion with an oxygenous gas is burnt in a gas turbine so that mechanical energy is generated and the waste gas evaporates water in a waste heat boiler by indirect heat exchange so that hot steam is generated, wherein a part-stream of the cooled waste gas is metered to the combustion air of the gas turbine after having left the waste heat boiler, this stream being fed to the gas turbine for combustion, and another part-stream of the cooled waste gas is fed to a gas scrubber for the absorption of acid gases after having left the waste heat boiler, with carbon dioxide CO 2  being recovered from the said gas scrubber. 
     
     
         2 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine, in which a fuel gas suitable for combustion with an oxygenous gas is burnt with an oxygen-enriched gas in a gas turbine so that mechanical energy is generated and the waste gas evaporates water in a waste heat boiler by indirect heat exchange so that hot steam is generated, wherein a part-stream of the cooled waste gas is metered to the combustion air of the gas turbine after having left the waste heat boiler, and the other part-stream is cooled in a cooler so that water condenses and carbon dioxide is recovered. 
     
     
         3 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 2 , wherein the other part-stream of the cooled waste gas is fed to a gas scrubber for the absorption of acid gases after having left the waste heat boiler, with carbon dioxide being recovered from the said gas scrubber. 
     
     
         4 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 2 , wherein the oxygen-enriched gas is pure oxygen and the other part-stream is cooled so that water condenses and carbon dioxide is recovered. 
     
     
         5 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the fuel gas is synthesis gas. 
     
     
         6 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 5 , wherein the synthesis gas originates from a coal gasification reaction in which a finely ground carbonaceous fuel gas is gasified with an oxygenous gas in an entrained flow reaction. 
     
     
         7 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the fuel gas is natural gas. 
     
     
         8 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the fuel gas is a refinery gas. 
     
     
         9 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the fuel gas is biogas. 
     
     
         10 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the carbon dioxide obtained is compressed and injected into a carbon dioxide storage site. 
     
     
         11 . The process for the metered recycling of cooled waste gas from the waste heat boiler of a gas turbine according to  claim 1 , wherein the portion of the recycled gas stream from the waste heat boiler and the amount of the part-stream metered into the gas turbine are controlled by the values measured for the temperature of the waste gas from the gas turbine.