Low CO2 Thermal Powerplant

Abstract

A method for generation of electrical power mainly from a coal based fuel, where the combustion gas is separated into a CO 2 rich stream and a CO 2 poor stream in a CO 2 capturing unit, the CO 2 poor stream is released into the surroundings, and the CO 2 rich stream is prepared for deposition or export, is described. A plant for executing the method and a preferred injector for the plant, is also described

1 . A method for generation of electrical power mainly from a coal based fuel, where the coal based fuel and an oxygen containing gas are introduced into a combustion chamber and combusted at an elevated pressure, the combustion gases are cooled down in the combustion chamber by generation of steam for production of electricity, the combustion gas is further cooled down and separated into a CO 2  rich stream and a CO 2  poor stream in a CO 2  capturing unit, the CO 2  poor stream is reheated and expanded over a turbine to produce electrical power, before the CO 2  poor stream is released into the surroundings, wherein the CO 2  rich stream is split into a stream for deposition or export, and a stream that is recycled to the combustion chamber. 
     
     
         2 . The method according to  claim 1 , wherein at least a portion of the CO 2  rich stream that is recycled to the combustion chamber is mixed with the coal based fuel before introduction to the combustion chamber and is injected into the combustion chamber together with the coal based fuel. 
     
     
         3 . The method according to  claim 1 , wherein the CO 2  poor stream is heated by heat exchanging against combustion gas from a secondary combustion chamber fired by gas, before the CO 2  poor stream is expanded over a turbine. 
     
     
         4 . The method according to  claim 1 , wherein the pressure in the combustion chambers is from 5 to 35 bar. 
     
     
         5 . The method according to  claim 4 , wherein the pressure is from 10 to 20 bar, more preferably from about 12 to about 16 bar. 
     
     
         6 . The method according to  claim 1 , wherein the temperature in the combustion gas leaving the combustion chamber, is reduced to below about 350° C. by production of steam. 
     
     
         7 . The method according to  claim 1 , wherein natural gas in introduced into the combustion chamber to support the combustion. 
     
     
         8 . A thermal power plant mainly fired with a coal based fuel, the thermal power plant comprising a combustion chamber ( 25 ), means ( 21 ) for introducing the coal based fuel and an oxygen containing gas into the combustion chamber ( 25 ), cooling means for cooling the combustion gas in the combustion chamber and means ( 49 ) for separation of the combustion gas into a CO 2  rich stream and a CO 2  poor stream, wherein the power plant additionally comprises a line ( 54 ) for recirculation of a part of the CO 2  to the combustion chamber and a CO 2  line ( 55 ) for delivering the remaining CO 2  rich stream for deposition or export. 
     
     
         9 . The thermal power plant according to  claim 8 , wherein the cooling means are cooling coils ( 9 ) inside the combustion chamber ( 25 ), where the cooling coils are cooling the combustion gas by generation of steam. 
     
     
         10 . The thermal power plant according to  claim 9 , further comprising a steam turbine ( 28 ) connected to a generator ( 27 ) for the production of electrical power. 
     
     
         11 . The thermal power plant according to  claim 8 , further comprising a secondary combustion chamber ( 81 ) fired by gas, for generation of heat for heating the CO 2  poor stream, and turbine ( 61 ) for expanding of the heated CO 2  poor stream before it is released into the surroundings. 
     
     
         12 . The thermal power plant according to  claim 11 , wherein the turbine ( 61 ) is connected to a generator ( 65 ) for production of electrical power. 
     
     
         13 . An injector for a coal based fuel and an oxygen-containing gas into a pressurized combustion chamber, comprising a central pipe ( 102 ) for injection of a mixture of pulverized coal based fuel and CO 2  gas, surrounded by a plurality of injectors ( 103 ) for oxygen containing gas. 
     
     
         14 . The injector according to  claim 13 , additionally comprising one or more gas injectors ( 104 ) for injection of natural gas. 
     
     
         15 . The injector according to  claim 13 , wherein helically ribs ( 105 ) are provided inside the central pipe ( 102 ). 
     
     
         16 . The injector according to  claim 15 , wherein the gas injectors ( 104 ) are orientated so the gas rotates the opposite way relative to the coal powder. 
     
     
         17 . The method according to  claim 2 , wherein the CO 2  poor stream is heated by heat exchanging against combustion gas from a secondary combustion chamber fired by gas, before the CO 2  poor stream is expanded over a turbine. 
     
     
         18 . The method according to  claim 2 , wherein the pressure in the combustion chambers is from 5 to 35 bar. 
     
     
         19 . The method according to  claim 3 , wherein the pressure in the combustion chambers is from 5 to 35 bar. 
     
     
         20 . The method according to  claim 2 , wherein the temperature in the combustion gas leaving the combustion chamber, is reduced to below about 350° C. by production of steam.