Abstract:
A low carbon emissions, combined cycle power plant utilizes vortex nozzles ( 38 ) operative at cryogenic temperatures to separate out carbon dioxide ( 39 ) from the flue gases. Complexity of the plant is minimized by operating a gas turbine engine component ( 10 ) of the plant at a turbine exhaust pressure of at least 2 bar, so that downstream components of the plant, including a heat recovery steam generator ( 19 A), a gas cooling system ( 30, 33, 36 ), and the inlets of the vortex nozzles, all operate at the same pressure of at least two bar. To increase carbon dioxide concentration in the flue gases ( 37 ) that pass through the vortex nozzles ( 38 ), and thereby increase efficiency of carbon dioxide removal from the flue gases, up to 50% of the flue gases that exit the heat recovery steam generator ( 19 A) may be recirculated to a location (L, FIG.  4 )) in the compressor of the gas turbine engine where the pressure of the compressor air matches the flue gas pressure.

Description:
[0001]    This application is a Continuation of, and claims priority under 35 U.S.C. §120 to, International application number PCT/EP2009/050727, filed 22 Jan. 2009, and claims priority under 35 U.S.C. §119 therethrough to European application number 08101260.1, filed 4 Feb. 2008, the entireties of which are incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Field of Endeavor 
         [0003]    The present invention relates to the field of climate protection technology, and in particular to reduced complexity and increased efficiency of carbon capture in combined cycle power plants, in which waste heat from a gas turbine engine is used to raise steam for a steam turbine. 
         [0004]    2. Brief Description of the Related Art 
         [0005]    Devices for production and separation of carbon dioxide (CO 2 ) from gas streams, using cryogenic separation units in the form of vortex nozzles (also called cyclonic separators), are known from prior published patent applications WO-A2-03/029739 and US-A1-2003/0145724. To operate efficiently at ambient temperatures, such vortex nozzles require to be fed by cooled gas streams pressurized to at least 2 or 3 bar at the inlets to the vortex nozzles. Within the vortex nozzles, the gases expand rapidly to much lower pressures, rapidly cooling the gas. A prior International patent application PCT/EP2007/057434, filed 7 Aug. 2006, uses vortex nozzles in an improved process for separating CO 2  from a gas flow, such as the exhaust from a gas turbine engine burning a fossil fuel. In general terms, the process includes: compressing the gas flow to a pressure of about 2-3 bar, cooling it down to about −40° C. to −50° C., supersonically expanding it through vortex nozzles so that solid CO 2  centrifugally precipitates from the rest of the gas flow, and discharging the CO 2  from the outer wall of the vortex nozzle for further treatment, such as preparation for sequestration. 
         [0006]      FIG. 1  diagrammatically illustrates a known type of sequential arrangement of plant components for a CO 2  capture process specifically adapted for use in conjunction with a combined cycle power plant. A gas turbine engine  10  compresses intake air  11  in a compressor  12 , burns fuel in the compressed air  13  in a combustor  14 , and obtains work from the combustion gases  15  in a turbine  16 , which drives the compressor  12  via a common shaft  17 . The major part of the mechanical power developed in turbine  16  is used to drive the electrical generator G. After expansion through the turbine  16 , the exhaust gases  18  are typically at about atmospheric pressure and contain about 3-4 volume % CO 2 . The hot exhaust or flue gases  18  exit from the exhaust duct of turbine  16  and are passed through a heat recovery steam generator (HRSG)  19  which raises steam  20  for expansion through a steam turbine  21  to generate further power from a generator G, driven through a shaft on which steam turbine  21  is mounted. After exit from the steam turbine  21 , the wet steam  22  is passed through a condenser  23 , and the condensed water  24  is then recycled to the HRSG  19  by pump P. After giving up much of their heat in the HRSG  19 , the flue gases  25  remain at about atmospheric pressure, but have been reduced to a temperature of about 80-120° C. Gases  25  are then cooled down to approximately ambient temperature (typically the temperature of available cooling water+10 K) in a heat exchanger  26 . The cooling water used in the heat exchanger  26  may, for example, be re-cooled in one or more cooling towers, or environmental water from a river, lake or sea, could be used to cool the flue gases  25 . 
         [0007]    As previously mentioned, carbon dioxide separation in a vortex nozzle requires the gases to be pressurized in the range 2 to 3 bars, at least. The cooled flue gas  27  is therefore compressed in a gas compressor  28 , driven by a motor M 1 , which may be powered by electricity generated by the gas turbine  10  and the steam turbine  21 . Alternatively, the gas compressor  28  maybe directly coupled to the shafts of either the gas or the steam turbine. The compressed flue gases  29  must then be cooled down to a temperature of −40 to −50° C. before the CO 2  can be cryogenically separated in a set of vortex nozzles  38  whose inlets are arranged to receive flue gases in parallel with each other (only one nozzle is shown). This is achieved by a flue gas cooling system operating in a three-stage process. In the first cooling stage, the compressed flue gas is cooled back down towards ambient temperature (again, typically the temperature of available cooling water+10 K) in a suitable heat exchange arrangement  30 . The second and third stages comprise active cooling cycles or other refrigeration apparatus. In the present example heat pumps are used, these being generally indicated by numerals  33  and  36 . As known, each heat pump  33 / 36  includes an evaporator  331 / 361 , a compressor  332 / 362  driven by a motor M 2 , a condenser  333 / 363 , and a metering valve  334 / 364 . Hence, in the second cooling stage, flue gas  31  from the first cooling stage passes through the evaporator  331  of active cooling cycle  33 . Flue gas  34  leaves evaporator  331  at a temperature which is 2 to 5 K above the freezing point of water, the evaporator being equipped with a suitable known device for separating condensed water from the flue gas. In the third cooling stage, flue gas  34  from the second stage is further cooled down to the required temperature of −40° C. to −50° C. by an evaporator  361  of the second active cooling cycle  36 . Evaporator  361  must be equipped with a suitable device for removing ice deposited on the heat exchanger surfaces during cooling of the flue gas. Finally, compressed cooled flue gas  37  enters the vortex nozzles  38 , where it is cooled by expansion and centrifugally separated into a CO 2  stream  39  and a residual flue gas stream  43 . The CO 2  stream  39  is cleaned, compressed by gas compressor  40  and fed into a pipeline  41  for storage, while the residual flue gas  44  is discharged into the atmosphere through a flue, stack (S), or the like, after undergoing further environmental cleaning procedures, if necessary. 
         [0008]    To increase system efficiency, the condenser  363  for refrigerant in the second active cooling cycle is placed downstream of the vortex nozzles  38  so that the cold, CO 2 -depleted flue gas  43  exhausted from the vortex nozzle  38  can be used as a heat sink. 
         [0009]    The CO 2  capture/separation process will not be further described here because it is adequately described in the above-mentioned prior patent application and other prior art. 
         [0010]    Without the provision of CO 2  capture equipment in  FIG. 1 , the flue gas would simply be ejected to atmosphere after leaving the HRSG  19 . However, to obtain the cool pressurized flue gas required for feeding into the vortex nozzle  38 , a compressor  28  and the cooling units  26 ,  30 ,  331 , and  361  are required, resulting in plant complexity and costs in construction, running and maintenance. 
       SUMMARY 
       [0011]    According to one of numerous aspects of the present invention, a low carbon emissions combined cycle power plant utilizes vortex nozzles to separate out carbon dioxide from flue gases at cryogenic temperatures, and the plant&#39;s complexity is minimized, by operating a gas turbine engine part of the plant with a turbine exhaust pressure and pressure of the downstream parts of the plant located between the gas turbine engine and the vortex nozzles at a pressure, which is high enough to assure an inlet pressure to the vortex nozzle of at least 2 bar. In consequence the turbine exhaust pressure is the required inlet pressure of the vortex nozzle plus the pressure losses of all components and duct between the turbine exit and the inlet of the vortex nozzle. 
         [0012]    Such downstream parts of the plant preferably include a heat recovery steam generator (HRSG) and a gas cooling system. The gas cooling system preferably includes a heat exchange arrangement operable to cool flue gases received from the HRSG down to a temperature approximating normal ambient temperature and active cooling apparatus operable to further cool the flue gases down to a temperature range of roughly −40° C. to −50° C. 
         [0013]    In more detail, a low carbon emissions combined cycle power plant embodying principles of the present invention includes: 
         [0014]    a gas turbine engine fuelled by carbon-containing fuel and operable to exhaust carbon dioxide-containing flue gases from a turbine exhaust duct; 
         [0015]    a heat recovery steam generator (HRSG) operable to raise steam by cooling flue gases received from the turbine exhaust duct; 
         [0016]    a steam turbine operable to produce shaft power from steam received from the HRSG; 
         [0017]    a heat exchanger arrangement operable to cool flue gases received from the HRSG down to a temperature approximating normal ambient temperature; 
         [0018]    active cooling apparatus operable to further cool the flue gases down to a temperature range of roughly −40° C. to −50° C.; and 
         [0019]    a plurality of vortex nozzles, each vortex nozzle having an inlet to receive flue gases from the active cooling apparatus and being operable to separate out carbon dioxide cryogenically from the received flue gases and to emit carbon-dioxide-depleted flue gases; 
         [0020]    wherein, in use, the gas turbine engine exhaust duct, the HRSG, the heat exchanger arrangement, and the active cooling apparatus operate at a pressure which is high enough to assure entry of the flue gases to the vortex nozzles to operate at a pressure of at least roughly 2 bar, preferably at a pressure in the range of roughly 2 to 4 bar. 
         [0021]    Preferably, the plant further comprises: 
         [0022]    a gas compressor operable to compress separated carbon dioxide received from the vortex nozzles and pass it to a pipeline for conveyance to storage; and 
         [0023]    a flue gas discharge stack or the like to receive the carbon-dioxide-depleted flue gases and discharge them to atmosphere, optionally after removal of further pollutants from the flue gases. 
         [0024]    In a plant of this sort, several to many vortex nozzles will be arranged in parallel with each other to process the gases received from the active cooling apparatus. 
         [0025]    To increase the percentage of carbon dioxide in the exhaust gases of the gas turbine engine, and thereby make the carbon dioxide removal process more efficient, the plant may be provided with a flow diverter located between the HRSG and the heat exchange arrangement and operative to recirculate a proportion (e.g., 10%, 20%, 30%, 40% or up to 50%) of the gases that pass through the HRSG by injecting them into a compressor of the gas turbine engine (GT compressor) at a location whose pressure is substantially the same as the pressure of the recirculated gases. 
         [0026]    The plant may be adapted by the designer to inject the recirculated gases into the GT compressor at a desired temperature chosen in accordance with the thermodynamic cycle it is desired to adopt. Thus, to minimize mixing losses in the GT compressor, the temperatures of the recirculated injected gases and the GT compressor air at the injection location should be substantially the same as each other. Alternatively, if the recirculated gases are injected into the GT compressor at a substantially lower temperature than the temperature of the GT compressor air at the injection location L, thermodynamic cycle improvements can be achieved analogous to those attributable to compressor intercooling. Such cooling of the recirculated flue gases could provide increased engine power output and cycle thermal efficiency without exceeding the temperature limits of the GT compressor and combustor. 
         [0027]    It would be possible to adapt the design of the HRSG so that it is capable of cooling the flue gases all the way down to the desired temperature for injection into the GT compressor. Alternatively, the HRSG could cool the flue gases part of the way down to the desired temperature and a gas cooler between the flow diverter and the GT compressor could cool the gases the remainder of the way down to the desired temperature. 
         [0028]    In one embodiment, the HRSG incorporates a flow diverter so that a desired proportion of the flue gases are diverted to the GT compressor before the gases have passed completely through the HRSG. If the part of the HRSG between its inlet and the flow diverter is not capable of cooling the flue gases all the way down to a desired temperature for injection of the flue gases to the GT compressor, there could be a gas cooler between the flow diverter in the HRSG and the GT compressor to further cool the diverted flue gases to the desired temperature. 
         [0029]    The gas turbine engine used in the plant may be a modified version of a pre-existing engine having a plurality of turbine stages and operative with a pressure in the turbine exhaust duct of approximately 1 bar, the modified version having at least one turbine stage less than the pre-existing engine, whereby the modified version is operative with a pressure in the turbine exhaust that is the above-mentioned required inlet pressure of the vortex nozzle plus the pressure losses of the downstream parts of the plant located between the gas turbine engine and the vortex nozzles. 
         [0030]    Another aspect of the present invention embraces a process for obtaining low carbon emissions from a combined cycle power plant that includes a gas turbine engine fuelled by carbon-containing fuel such that the engine exhausts carbon dioxide-containing flue gases, the process further comprising: 
         [0031]    a first cooling step in which the flue gases are cooled by using them to raise steam to drive a steam turbine to produce shaft power; 
         [0032]    a second cooling step in which the flue gases are further cooled to a temperature approximating normal ambient temperature; 
         [0033]    a third cooling step in which the flue gases are further cooled to a temperature range of approximately −40° C. to −50° C.; 
         [0034]    a cryogenic separation step comprising separating carbon dioxide from the flue gases and emitting carbon dioxide depleted flue gases; 
         [0035]    wherein exhaustion of the flue gases from the gas turbine engine and cooling of the flue gases occurs at a pressure which is high enough to assure entry to the cryogenic separation step of at least roughly 2 bar. 
         [0036]    Further aspects of the invention will be apparent from a perusal of the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    Exemplary embodiments of the invention will now be described, with reference to the accompanying drawings, in which: 
           [0038]      FIG. 1  is a flow diagram illustrating a known type of combined cycle plant with an added CO 2  capture facility; 
           [0039]      FIG. 2  is a flow diagram illustrating a simplified version of the plant of  FIG. 1  according to a first embodiment of the invention; 
           [0040]      FIG. 3  is a flow diagram illustrating a known type of combined cycle plant with flue gas recirculation and an added CO 2  capture facility; and 
           [0041]      FIGS. 4A to 4C  are flow diagrams illustrating simplified versions of the plant of  FIG. 3  according to second, third and fourth embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0042]    In  FIGS. 1 to 4 , plant components and fluid flows which are the same or closely similar in different Figures have been given the same reference numerals and will not be described again if they have been described for an earlier Figure. 
         [0043]    Referring to  FIG. 2  and comparing it with  FIG. 1 , it will be seen that the complexity of the plant has been reduced by omitting the gas cooler  26  and the compressor  28 . This simplification is enabled by increasing the exhaust pressure of the turbine  16 A of gas turbine engine  10 A, compared with the original turbine  16  of gas turbine engine  10 . Practically, this can be achieved by removing at least the last stage of the turbine  16 . The number of turbine stages removed from turbine  16 , to achieve the modified turbine  16 A, will depending on the type of existing engine being considered for use in conjunction with embodiments adhering to principles of the present invention, but is likely to be one or two, and unlikely to be more than three stages. 
         [0044]    As an alternative to the modification of an existing gas turbine engine, it would of course be possible to create a new design of engine capable of giving a desired increase in exhaust pressure. In a modified design or a new design, a benefit may arise from turbine  16 A having fewer turbine stages than is normal for a gas turbine engine in a combined cycle power plant, in that it may allow turbine  16 A to be designed for increased mass flow and power. This possibility arises because the greater length and weight of the turbine rotor blades in the final stages of the turbine  16  causes the blades and the rotors on which they are mounted to be the most highly stressed components in the turbine. They are therefore limiting factors in terms of the turbine&#39;s mechanical integrity. 
         [0045]    Assuming that turbine  16 A of  FIG. 2  has between one and three fewer stages than turbine  16  of  FIG. 1 , the pressure of the flue gas will still be in the range 2 to 4 bar at the exit of the HRSG  19 A, thereby enabling omission of a compressor from the subsequent process of  FIG. 2 . 
         [0046]    Note that an increase in turbine exhaust temperature will accompany the increased turbine exhaust pressure. Consequently, in comparison with the HRSG  19  of  FIG. 1 , the HRSG  19 A of  FIG. 2  must be constructed to withstand the higher pressure and temperature of the flue gases  18 A issuing from the turbine exhaust. Because HRSG  19 A will operate at increased temperature and pressure compared to HRSG  19 , it will have an increased heat flow rate and may have a better heat exchange efficiency. Nevertheless, to enable elimination of the gas cooler  26  ( FIG. 1 ), it may be necessary to provide HRSG  19 A with a significantly larger heat exchange area than HRSG  19 . Whatever the construction of HRSG  19 A, heat exchanger  30  should be constructed to be capable of cooling the flue gas  25 A that exits from HRSG  19 A to approximately ambient temperature (typically the temperature of available cooling water+10 K). 
         [0047]    The subsequent stages of the process in  FIG. 2  are the same or closely similar to the process outlined in  FIG. 1 , and will therefore not be further described. 
         [0048]    The power output of the  FIG. 2  embodiment will be closely comparable with the net power output of the  FIG. 1  plant, but with a substantially simpler plant arrangement. 
         [0049]    Although  FIGS. 2 to 4C  indicate only one vortex nozzle  38 , there will in fact be an array of vortex nozzles receiving the flue gases in parallel with each other. 
         [0050]      FIG. 3  diagrammatically illustrates a known type of sequential arrangement of plant components for a CO 2  capture process specifically adapted for use in conjunction with a combined cycle power plant having exhaust gas recirculation. It includes a modified form of the plant in  FIG. 1 , in which it is assumed that the following plant parameters are the same in both  FIG. 1  and  FIG. 3 : 
         [0051]    the mass flow rate through the turbine  16 ; 
         [0052]    the shaft power generated by the gas turbine engine  10  and the steam turbine  21 ; 
         [0053]    the flue gas pressures and temperatures at the entry and exit of the HRSG  19  and the gas cooler  26 , and their heat flow rates; and 
         [0054]    the heat energy recovered from the flue gases by the HRSG  19 . 
         [0055]    As in  FIG. 1 , the flue gas  25  that exits the HRSG  19  in  FIG. 3  is further cooled in the gas cooler  26 . After gas cooler  26 , the flue gas  27  is at or near ambient pressure and temperature (i.e., the temperature of the available cooling water+10 K). At this point, it is split into two streams by a diverter  45 , one stream  46  being returned to the inlet of the compressor  12  of the gas turbine engine  10  and the other stream  48  being forwarded to the gas compressor  28  and the cooling units  30 ,  331 ,  361  in preparation for entry to the vortex nozzles  38 . Before entry to the compressor  12 , the recirculated flue gas stream  46  is mixed with a stream of ambient air  11 A in a gas mixer  47 . It is assumed here that about 50% of the flue gas  27  is recirculated, though lesser proportions of flue gas recirculation, e.g., in the range 10% to 50%, would also be worthwhile. 
         [0056]    A purpose of exhaust gas recirculation is to increase the CO 2  concentration in the turbine exhaust gas  18 B, thus facilitating more efficient separation of the CO 2  in the vortex nozzles  38 . In comparison with  FIG. 1 , the arrangement of  FIG. 3 , assuming 50% recirculation, increases the CO 2  content of the flue gases from about 3 to 4 vol. % to about 6 to 8 vol. %. Of course, if lower proportions of the flue gases are recirculated, their CO 2  content will be correspondingly reduced. 
         [0057]    Again assuming 50% recirculation, the mass flow rate of the non-recirculated flue gas stream  48  in  FIG. 3  will be only half that of flue gas stream  27  in  FIG. 1 , meaning that the compressor  28  will impose only half the power drain on the plant compared with compressor  28  in  FIG. 1 . Furthermore, the power that is required to run the active cooling cycles  33  and  36  is also reduced to one half. Proportions of recirculated flue gases  46  that are less than 50% will of course result in lower power savings in compressor  28  and active cooling cycles  33  and  36 . 
         [0058]    In  FIG. 4A , a simpler process is proposed. In comparison with  FIG. 3 , compressor  28 , cooler  26 , and gas mixer  47  are eliminated by increasing the pressure of the gas turbine exhaust gas  18 B and the cooling ability of the HRSG  19 A. As was the case for the embodiment of  FIG. 2 , increased exhaust pressure is achieved by removing at least the final stage of the turbine  16  of  FIG. 3 , resulting in the benefits already mentioned for the turbine  16 A. As was the case for  FIG. 2 , it is assumed that the exhaust gas pressure is increased to between 2 to 4 bar, with corresponding increase in temperature, and corresponding changes to the construction of HRSG  19 A. 
         [0059]    The skilled person will appreciate that in exhaust gas recirculation processes, the recirculated gas should be injected into the gas turbine engine&#39;s compressor at a location where the pressure of the recirculated gas is substantially the same as the pressure in the compressor. Hence, in  FIG. 3 , after mixing with ambient air at atmospheric pressure, the recirculated gases  46  are injected into the intake of the compressor  12 , but in  FIG. 4A , recirculated gases  46 A are injected at an inter-stage location L part-way through the compressor. 
         [0060]    Note that the temperature of the recirculated gases when injected into the compressor of the gas turbine engine will depend on the thermodynamic cycle adopted by the designer. 
         [0061]    In a first possible cycle, it is arranged that the temperature of the recirculated flue gases  46 A substantially matches the compressor air temperature at the injection location L. This strategy minimises mixing losses in the compressor. 
         [0062]    In a second possible cycle, it is arranged that the recirculated gases  46 A are injected into the compressor  12 A at a substantially lower temperature than the temperature of the compressor air at the injection location L. This strategy achieves thermodynamic cycle improvements in a manner analogous to that achieved by compressor intercooling, i.e., it provides increased engine output power and thermal efficiency without exceeding the temperature limits of the engine&#39;s compressor and combustor. 
         [0063]    At least in the first of the above suggested thermodynamic cycles, and perhaps also in the second, the required temperatures of the recirculated flue gases could be achieved by appropriate construction (e.g., amount of heat exchange area) of the HRSG  19 A. Alternatively,  FIG. 4B  proposes that the temperature of the recirculated gases  46 A be further reduced after diversion and prior to injection by a gas cooler  50  inserted between the diverter  45  and the compressor  12 A. 
         [0064]    A further variation embodying principles of the invention is shown in  FIG. 4C . Here, it is assumed that HRSG  19 B incorporates a diverter (not shown) that functions similarly to diverter  45  in  FIGS. 3 to 4B  to divert a proportion  52  of the flue gases to the location L in the compressor  12 A. The first part of the HRSG  19 B, between the inlet for flue gases  18 B and the HRSG&#39;s diverter, may be designed to cool the flue gases  18 B to a temperature at least approaching (or perhaps even lower than), the temperature of the compressor air at the location L. However, if it is deemed necessary to attain a flue gas injection temperature that is lower than that attainable by cooling in the first part of the HRSG  19 B, the flue gases may be further cooled after diversion by a gas cooler  54  (shown in broken lines) inserted between the diverter in the HRSG and the location L in the compressor  12 A. The second part of the HRSG  19 B, between the HRSG&#39;s diverter and the exit for flue gases  25 A, is designed to cool the remaining flue gases  25 B to a temperature low enough to enable gas cooler  30  to cool them to a temperature at least approaching ambient. 
         [0065]    As is well known, the recirculated gases cannot be injected at only one point in compressor  12 A. As a matter of practicality, location L will include a single axial location within the compressor  12 A, but will extend around its circumference so that the inflow of recirculated gases is at least approximately evenly distributed around that circumference. 
         [0066]    An advantage of the embodiments of  FIGS. 4A  to C should be noted, in that recirculation of the flue gases to a location L part-way along the compressor  12 A reduces its power requirement relative to compressor  12  in  FIG. 3 . If the mass flow rates out of the compressors  12  and  12 A are the same, there will be a reduced compressor inlet flow  11 B relative to inlet flow  11 A in  FIG. 3 , so it will be possible to have shorter compressor blades in the stage(s) before the location L at which the recirculated gases are injected. This not only saves material and manufacturing expense, but also reduces compressor rotor blade tip speed, with correspondingly reduced stresses in the blades. 
         [0067]    The remaining part of the cooling and CO 2  removal process in  FIGS. 4A to 4C  is as previously described for  FIG. 1 . 
         [0068]    Whereas  FIGS. 1 to 4C  diagrammatically illustrate a standard type of non-reheated gas turbine engine as part of the combined cycle plant, principles of the present invention would of course also be applicable to combined cycle plants that include reheated gas turbine engines. Such engines have two sequentially arranged combustion stages for greater thermodynamic efficiency, a high pressure turbine being arranged to take some of the energy out of the gases from the first combustion stage before passing the gases to the second combustion stage for reheat. 
         [0069]    The present invention has been described above purely by way of example, and modifications can be made within the scope of the invention as claimed. Principles of the present invention also extend to any individual features described or implicit herein or shown or implicit in the drawings or any combination of any such features or any generalisation of any such features or combination, which extends to equivalents thereof. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Each feature disclosed in the specification, including the claims and drawings, may be replaced by alternative features serving the same, equivalent or similar purposes, unless expressly stated otherwise. 
         [0070]    Any discussion of the prior art throughout the specification is not an admission that such prior art is widely known or forms part of the common general knowledge in the field. 
         [0071]    Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. 
       LIST OF REFERENCE SYMBOLS 
       [0072]    G: generator 
         [0073]    M 1 , M 2 : electric motors 
         [0074]    P: pump 
         [0075]    S: discharge flue/stack 
         [0076]      10 ,  10 A,  10 B,  10 C: gas turbine engine 
         [0077]      11 ,  11 A,  11 B: compressor intake air 
         [0078]      12 ,  12 A: compressor of gas turbine engine 
         [0079]      13 : compressor exit air 
         [0080]      14 : combustor 
         [0081]      15 : combustion gases 
         [0082]      16 ,  16 A: turbine 
         [0083]      17 : shaft 
         [0084]      18 ,  18 A,  18 B: flue gases from turbine 
         [0085]      19 ,  19 A,  19 B: heat recovery steam generator (HRSG) 
         [0086]      20 : steam 
         [0087]      21 : steam turbine 
         [0088]      22 : wet steam 
         [0089]      23 : condenser 
         [0090]      24 : water 
         [0091]      25 ,  25 A,  25 B: flue gases from HRSG 
         [0092]      26 : heat exchanger (gas cooler) 
         [0093]      27 : flue gases from  26   
         [0094]      28 : flue gas compressor 
         [0095]      29 : flue gases from  28   
         [0096]      30 : heat exchanger (gas cooler) 
         [0097]      31 : flue gases from  30   
         [0098]      33 : first active cooling cycle/heat pump 
         [0099]      331 ,  361 : evaporators 
         [0100]      332 , 362 : refrigerant compressors 
         [0101]      333 ,  363 : condensers 
         [0102]      334 ,  364 : expansion/metering valves 
         [0103]      34 : flue gases from  33   
         [0104]      36 : second active cooling cycle/heat pump 
         [0105]      37 : flue gases from  36   
         [0106]      38 : vortex nozzles 
         [0107]      39 : CO 2    
         [0108]      40 : CO 2  compressor 
         [0109]      41 : CO 2  pipeline 
         [0110]      43 ,  44 : CO 2  -depleted flue gases for discharge 
         [0111]      45 : flow diverter 
         [0112]      46 ,  46 A,  46 B: recirculated flue gases from  45   
         [0113]      47 : gas mixer 
         [0114]      48 ,  48 A: non-recirculated flue gases from  45   
         [0115]      50 : heat exchanger/gas cooler 
         [0116]      52 : recirculated flue gases from flow diverter within HRSG  19 B 
         [0117]      54 . heat exchanger (gas cooler) 
         [0118]    While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.