Coal-fired power station and method for operating the coal-fired power station

Abstract

In a method for operating and controlling/regulating a power station comprising a coal-fired steam generator ( 11 ), the steam generator ( 11 ) of which is rated for the steam parameters achievable by the heat transfer onto the steam mass flow upon coal firing in the steam generator ( 11 ) carried out using combustion air, a solution is to be created, which enables the operation of coal-fired power stations rated for air operation utilizing a firing of the fuel carried out according to the oxy-fuel process in the firing chamber of the steam generator of the coal-fired power station. This is achieved in that a firing of the fuel containing coal is carried out in the steam generator ( 11 ) according to the oxy-fuel process utilizing approximately pure oxygen containing more than 95% by volume, and recirculated flue gas containing a high amount of CO 2 , such that the mass flows of all fuel flows supplied to the coal-fired burners ( 10 ) and to the steam generator ( 11 ), and the combustion gas, carrier gas, and process gas flows from the combustion oxygen and/or recirculated flue gas are configured and adjusted to each other with respect to the respective composition ratio thereof of oxygen and/or flue gas such that the heat transfer occurring in the steam generator by means of flame radiation, gas radiation, and convection onto the steam mass flow is maintained equal overall in the steam/water cycle as compared to air combustion, in particular, that the same steam parameters are obtained.

1 . A method for operating and for controlling a power station that comprises a coal-fired steam generator, the steam generator being designed for steam parameters that can be achieved for coal combustion, which is carried out with combustion air in the steam generator by heat transfer to the steam mass flow,
 wherein combustion of the fuel, which contains carbon, is carried out in the steam generator on the basis of the oxyfuel process with approximately pure oxygen, which contains more than 95% by volume of O 2 , and recirculated flue gas with a high CO 2  content, such that the mass flows of all the fuel flows as well as combustion gas flows, feed gas flows and process gas flows that are supplied to the coal-burners and to the steam generator are formed from combustion oxygen and/or recirculated flue gas in their respective composition ratio of oxygen and/or flue gas, and are matched to one another, such that the heat transfer that takes place in the steam generator by flame radiation, gas radiation and convection to the steam mass flow in the steam/water circuit of the steam generator is kept at least essentially the same overall in comparison to the air combustion.   
     
     
         2 . The method according to  claim 1 , wherein treated and/or untreated flue gas is fed back in a recirculating manner to the steam generator. 
     
     
         3 . The method according to  claim 1 , wherein an existing power station is retrofitted with the method as claimed in  claim 1 . 
     
     
         4 . The method according to  claim 1 , wherein the recirculation rate of the flue gas is 65% to 80%. 
     
     
         5 . The method according to  claim 1 , wherein the flue gas is tapped off after desulfurization or after a flue gas desulfurization installation or a flue gas cooler, which is installed additionally and/or subsequently, for recirculation. 
     
     
         6 . The method according to  claim 1 , wherein the flue gas is tapped off after a flue gas condensation drier in the flow direction. 
     
     
         7 . The method according to  claim 1 , wherein quicklime (CaO) is used as absorbent in the flue gas desulfurization installation. 
     
     
         8 . A power station having a coal-fired steam generator that is designed for steam parameters that can be achieved for coal combustion, which is carried out with combustion air, in the steam generator by heat transfer to the steam mass flow,
 wherein combustion of the fuel, which contains carbon, is carried out in the steam generator on the basis of the oxyfuel process with approximately pure oxygen, which contains more than 95% by volume of O 2 , and recirculated flue gas with CO 2  content, such that the mass flows of all the fuel flows as well as combustion gas flows, feed gas flows and process gas flows that are supplied to the coal-burners and to the steam generator are formed from combustion oxygen and/or recirculated flue gas in their respective composition ratio of oxygen and/or flue gas, and are matched to one another, such that the heat transfer that takes place in the steam generator by flame radiation, gas radiation and convection to the steam mass flow in the steam/water circuit of the steam generator remains the same overall in comparison to the air combustion.   
     
     
         9 . The power station according to  claim 8 , wherein a heat displacement system is installed between a suction draft and desulfurization or a desulfurization installation. 
     
     
         10 . The power station according to  claim 8 , wherein the flue gas channel has a bypass line that is routed parallel to an air preheater (LUVO) and has a gas/gas heat exchanger arranged therein, after a denitrification device in the flow direction. 
     
     
         11 . The method according to  claim 1 , wherein the recirculation rate of the flue gas is 74% to 78%. 
     
     
         12 . The method according to  claim 1 , wherein an existing 600° C. power station is retrofitted with the method as claimed in  claim 1 . 
     
     
         13 . The method according to  claim 1 , wherein the same steam parameters are maintained. 
     
     
         14 . The power station according to  claim 8 , wherein the resultant steam parameters remain the same.