Power generation system and method to operate

Abstract

A method to operate a power generation system and the device itself includes an oxy-fuel burner, a first heat exchanger assembly, and a rankine-cycle. The oxy-fuel burner generates an exhaust fluid submitted to an exhaust fluid line and the rankine-cycle is operated with the working media which is circulating separately from the exhaust fluid. The exhaust fluid line is provided with a recirculation line downstream the first heat exchanger assembly and upstream the working media heat exchanger extracting exhaust fluid from the exhaust fluid line, conducting extracted exhaust fluid to a compression unit to increase pressure and injecting downstream the extracted exhaust fluid into the oxy-fuel burner.

1 . A power generation system (PGS) comprising
 an oxy-fuel burner (OXB),   a first heat exchanger assembly (HEA 1 ),   a rankine-cycle (RC),   wherein said rankine-cycle (RC) comprises at least one turbine (ST) for expansion of a working media (PF), downstream said turbine (ST) at least one condenser (CON) for condensing of said working media (PF),   wherein said rankine-cycle (RC) comprises downstream said condenser (CON) at least one first working media pump (FWP 1 ) delivering said working media (PF) to a higher pressure level,   wherein said rankine-cycle (RC) comprises downstream said first working media pump (FWP 1 ) at least one first working media pre-heater (PH 1 ) heating said working media (PF) by extracted working media (XPF 2 ) from said turbine (ST),   wherein downstream said first working media pre-heater (PH 1 ) said working media (PF) passes said first heat exchanger assembly (HEA 1 ) to be boiled and superheated,   wherein said oxy-fuel burner (OXB) generates an exhaust fluid (EXH) by combustion of fuel (F) and oxygen enriched gas (O2), wherein a first part (EXH 1 ) of said exhaust fluid (EXH) is provided to an exhaust fluid line branch (EXLB) and a second part (EXH 2 ) of said exhaust fluid (EXH) is provided for recirculation to said oxy-fuel burner (OXB),   wherein said rankine-cycle (RC) is operated with said working media (PF) which is circulating separately from said exhaust fluid (EXH),   wherein said first part (EXH 1 ) of said exhaust fluid (EXH) is provided to at least one working media heat exchanger (FWE) that is provided to heat up said working media (PF) of said rankine-cycle (RC) downstream said first working media pump (FWP 1 ) and upstream said first working media pre-heater (PH 1 ) by said first part (EXH 1 ) of said exhaust fluid (EXH),   wherein said second part (EXH 2 ) of said exhaust fluid (EXH) is provided downstream of heat exchangers of said first heat exchanger assembly (HEA 1 ) to a compression unit (PU) to increase pressure of said second part (EXH 2 ) in order to re-inject said second part (EXH 2 ) into said oxy-fuel burner (OXB).   
     
     
         2 . The power generation system (PGS) according to  claim 1 ,
 wherein said power generation system (PGS) is operated at a pressure level for said exhaust fluid (EXH) of several bar above atmospheric.   
     
     
         3 . The power generation system (PGS) according to  claim 1 , further comprising
 a catalyst unit for cleaning of said exhaust fluid (EXH) from residual content of oxygen by addition of further fuel and/or other combustible media.   
     
     
         4 . The power generation system (PGS) according to  claim 1 ,
 wherein said turbine (ST) is a combination of at least a high pressure turbine (HPST) and a low pressure turbine (LPST),   wherein between said high pressure turbine (HPST) and said low pressure turbine (LPST) said working media (PF) is led through a reheater (AH 1 ),   wherein said reheater (AH 1 ) is part of said first heat ex-changer assembly (HEA 1 ), so that said working media (PF) is reheated by said exhaust fluid (EXH) downstream said high pressure turbine (HPST) and upstream said low pressure turbine (LPST).   
     
     
         5 . The power generation system (PGS) according to  claim 1 , further comprising
 at least one adjustable valve (CV) or a capacity control of said compression unit (PU) to control the flow of said second part (EXH 2 ) of said exhaust fluid (EXH).   
     
     
         6 . The power generation system (PGS) according to  claim 1 , further comprising
 in respect of a fluid flow of a mixed working media (PFM), upstream of said at least one first working media pre-heater (PH 1 ), a mixing pre-heater (MP) for mixing a third extracted working media (XPF 3 ) from said turbine (ST) with said working media (PF) downstream said condenser (CON) to result in said mixed working media (PFM).   
     
     
         7 . The power generation system (PGS) according to  claim 1 , further comprising
 upstream said oxy-fuel burner (OXB), an air separation unit (ASU) as part of said power generation system (PGS) to purify ambient air to generate said oxygen enriched gas (O2).   
     
     
         8 . The power generation system (PGS) according to  claim 1 ,
 wherein said power generation system (PGS) is set up such that temperature level at design working conditions for said second part (EXH 2 ) of said exhaust fluid (EXH) is at least ⅔ of saturation temperature measured in Celsius of boiling occurring in said first heat exchanger assembly (HEA 1 ).   
     
     
         9 . The power generation system (PGS) according to  claim 1 ,
 wherein said feed water heat exchanger (FWE) comprises an output port to release gaseous carbon dioxide (CO2) and other output port to release water (H2O), said carbon dioxide (CO2) and said water (H2O) separated from said first part (EXH 1 ) of said exhaust fluid (EXH) within said feed water heat exchanger (FWE).   
     
     
         10 . A method to operate a power generation system (PGS) comprising:
 providing an oxy-fuel burner (OXB), a first heat exchanger assembly (HEA 1 ), a rankine-cycle (RC),   generating an exhaust fluid (EXH) by said oxy-fuel burner (OXB) by burning oxygen enriched gas (O2) and fuel (F), wherein a first part (EXH 1 ) of said exhaust fluid (EXH) is provided to an exhaust fluid line branch (EXLB) and a second part (EXH 2 ) of said exhaust fluid (EXH) is provided for recirculation to said oxy-fuel burner (OXB),   expanding a working media (PF) in said rankine-cycle (RC) comprising at least one turbine (ST) of said rankine-cycle (RC),   condensing said working media (PF) downstream said turbine (ST) by at least one condenser (CON) of said rankine-cycle (RC),   delivering said working media (PF) to a higher pressure level downstream said condenser (CON) by at least one first working media pump (FWP 1 ) of said rankine-cycle (RC),   heating said working media (PF) by extracted working media (XPF 2 ) from said turbine (ST) downstream said first working media pump (FWP 1 ) by at least one first working media pre-heater (PH 1 ) of said rankine-cycle (RC),   boiling and superheating said working media (PF) downstream said first working media pre-heater (PH 1 ) by said first heat exchanger assembly (HEA 1 ) of said rankine-cycle (RC),   operating said rankine-cycle (RC) with said working media (PF) which is circulating separately from said exhaust fluid (EXH),   providing at least one working media heat exchanger (FWE) for heating up said working media (PF) of said rankine-cycle (RC) downstream said first working media pump (FWP 1 ) and upstream said first working media pre-heater (PH 1 ) by said first part (EXH 1 ) of said exhaust fluid (EXH),   routing said second part (EXH 2 ) to a compression unit (PU) to increase pressure of said second part (EXH 2 ) in order to inject said second part (EXH 2 ) into said oxy-fuel burner (OXB).   
     
     
         11 . The method according to  claim 10 , further comprising:
 providing said turbine (ST) as a combination of at least a high pressure turbine (HPST) and a low pressure turbine (LPST),   conducting said working media (PF) is through a reheater (AH 1 ) located downstream of said high pressure turbine (HPST) and upstream of said low pressure turbine (LPST),   wherein said reheater (AH 1 ) is part of said first heat ex-changer assembly (HEA 1 ), so that said working media (PF) is reheated by said exhaust fluid (EXH) downstream said high pressure turbine (HPST) and upstream said low pressure turbine (LPST).   
     
     
         12 . The method according to  claim 10 , further comprising:
 controlling the flow through said recirculation line (RCL) by at least one adjustable valve (CV) or by speed control of said compression unit (PU).   
     
     
         13 . The method according to  claim 10 , further comprising:
 mixing a third extracted working media (XPF 3 ) from said turbine (ST) with said working media (PF) downstream said condenser (CON) to a mixed working media (PFM) by a mixing pre-heater (MP), and providing the mixed working media (PFM) to said at least one first working media pre-heater (PH 1 ).   
     
     
         14 . The method according to  claim 10 , further comprising:
 providing an air separation unit (ASU) as part of said power generation system (PGS) to purify ambient air to generate said oxygen enriched gas (O2).   
     
     
         15 . The power generation system (PGS) according to  claim 1 ,
 wherein said power generation system (PGS) is operated at a pressure level for said exhaust fluid (EXH) of more than 5 bar above atmospheric.   
     
     
         16 . The power generation system (PGS) according to  claim 1 , further comprising
 a catalyst unit for cleaning of said exhaust fluid (EXH) from residual content of oxygen by addition of further fuel and/or other combustible media, connected such that heat of a catalyst process running in the catalyst unit is recovered for use in said rankine-cycle (RC) and/or for preheating of fuel (F) or said oxygen enriched gas (O2).