Method of operating a gas-turbine power plant, and gas-turbine power plant

Abstract

A method of operating a gas-turbine power plant, having a gas-turbine plant ( 1 ) in which an oxygen-containing gas is drawn in, compressed and fired and, after passing through a turbine stage, is fed as discharging hot gas ( 8 ) to a waste heat boiler ( 4 ), from which the cooled exhaust gas ( 9 ) is fed to an outlet ( 10 ) and then to the free atmosphere. A specific reduction in the flow velocity with which the exhaust gas ( 9 ) flows through the outlet ( 10 ) is effected in the region of the latter, with a simultaneous pressure increase downstream in the outlet ( 10 ), and in that the pressure conditions occurring inside the outlet ( 10 ) are transmitted free of losses between the gas turbine ( 1 ) and the outlet ( 10 ) via a gas-tight flow path of the hot and exhaust gases ( 8; 9 ).

What is claimed is:  
     
         1 . A method of operating a gas-turbine power plant, comprising: 
 drawing in an oxygen-containing gas;    compressing and heating the oxygen-containing gas while admixing a fuel;    expanding the hot gas produced in a gas turbine to perform work;    discharging the hot gas from the gas turbine and feeding the hot gas to an outlet via a flow path;    decelerating the exhaust-gas flow, at an essentially constant flow rate, in the region of the outlet; and    transmitting the pressure conditions produced by decelerating upstream of the region of the deceleration back via the flow path up to the outlet of the gas turbine, wherein the flow path is gas-tight relative to the atmosphere.    
     
     
         2 . The method as claimed in  claim 1 , wherein decelerating comprises decelerating the exhaust-gas flow in such a way that a low pressure occurs relative to the atmospheric ambient pressure upstream of the outlet.  
     
     
         3 . A gas-turbine power plant, comprising: 
 a device for compressing an oxygen-containing gas;    at least one combustion chamber for heating the compressed gas;    an outlet in fluid communication with said at least one combustion chamber and including a flow-limiting wall;    a diffuser arranged at a position in the flow direction selected from the group consisting of inside the outlet and downstream of the outlet;    at least one gas turbine in fluid communication with said at least one combustion chamber and including a flow path, an exit, and working stages, in which turbine hot gas produced expands to perform work and is then transferred into the flow path in which it passes through the working stages, and discharged into the atmosphere via the outlet;    wherein the flow path between the exit of the gas turbine and the outlet is essentially gas-tight relative to the atmosphere.    
     
     
         4 . The gas-turbine power plant as claimed in  claim 3 , wherein the outlet comprises a stack with a substantially uniform cross section of flow, and the diffuser is mounted on the stack.  
     
     
         5 . The gas-turbine power plant as claimed in  claim 4 , wherein the diffuser comprises an axial diffuser.  
     
     
         6 . The gas-turbine power plant as claimed in  claim 3 , further comprising: 
 a displacement body integrated at least approximately centrally in the cross section of flow in the region of the outlet, the displacement body having a spatial form so that it achieves a diffuser effect in interaction with the flow-limiting wall; and    wherein the displacement body narrows in the direction of flow and the flow-limiting wall adjacent to the displacement body is essentially cylindrical.    
     
     
         7 . The gas-turbine power plant as claimed in  claim 3 , wherein the outlet comprises a stack with a substantially uniform cross section of flow, and the diffuser comprises a radial diffuser.  
     
     
         8 . The gas-turbine power plant as claimed in  claim 7 , wherein the radial diffuser has a flow section arranged directly downstream of the stack in the direction of flow having a cross section of flow (D 2 ) larger than portions upstream thereof, wherein the flow section, at the larger cross section of flow (D 2 ), includes stationary flow surfaces deflecting the exhaust gas radially outward.  
     
     
         9 . The gas-turbine power plant as claimed in  claim 3 , wherein the outlet comprises a stack with a flow-limiting wall and a substantially uniform cross section of flow, and the diffuser comprises a semiaxial diffuser.  
     
     
         10 . The gas-turbine power plant as claimed in  claim 9 , wherein the semiaxial diffuser includes a displacement body integrated centrally in the cross section of flow, and the contour of the displacement body extends along the flow-limiting wall in such a way that a continuously widening cross section of flow is produced in the direction of flow.