US008596075B2

(12) United States Patent (10) Patent N0.: US 8,596,075 B2 Allam et a1. (45) Date of Patent: Dec. 3, 2013

(54) SYSTEM AND METHOD FOR HIGH (56) References Cited EFFICIENCY POWER GENERATION USING A CIRCULATING U.S. PATENT DOCUMENTS WORKING FLUID 3,376,706 A 4/1968 Angelino 3,503,208 A 3/1970 Schmidt (75) Inventors: Rodney John Allam, Wiltshire (GB); 3,736,745 A 6/1973 Karig Miles Palmer, Chapel Hill, NC (US); 3,837,788 A 9/1974 Craig et a1. Glenn William Brown, J r., Durham, NC 3,971,211 A 7/1976 Wethe et a1. (Us) 3,976,443 A 8/1976 Paull et a1. (Continued) (73) Assignees: Palmer Labs, LLC, Durham, NC (US); 8 Rivers Capital, LLC, Durham, NC FOREIGN PATENT DOCUMENTS (Us) JP 2225905 9/1990 Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 OTHER PUBLICATIONS U.S.C. 154(b) by 0 days. Hong et al., “Analysis of Oxy-Fuel Power Cycle Utiliz (21) Appl. N0.: 12/872,777 ing a Pressurized Coal Combustor,” Energy, Available Online Jun. 21, 2009, pp. 1332-1340, vol. 34, No. 9. (22) Filed: Aug. 31, 2010 (Continued) (65) Prior Publication Data US 2011/0179799 A1 Jul. 28, 2011 Primary Examiner * Ehud Gartenberg Assistant Examiner * Arun Goyal Related US. Application Data (74) Attorney, Agent, or Firm * Womble Carlyle Sand ridge & Rice, LLP (63) Continuation-in-part of application No. 12/714,074, ?led on Feb. 26, 2010. (60) Provisional application No. 61/299,272, ?led on Jan. (57) ABSTRACT 28, 2010, provisional application No. 61/155,755, The present invention provides methods and system for ?led on Feb. 26, 2009. poWer generation using a high ef?ciency combustor in com bination With a C02 circulating ?uid. The methods and sys Int. Cl. (51) tems advantageously can make use of a loW pressure ratio F 02C 1/00 (2006.01) poWer turbine and an economiZer heat exchanger in speci?c F 02C 7/08 (2006.01) embodiments. Additional loW grade heat from an external (52) US. Cl. source can be used to provide part of an amount of heat USPC ...... 60/772; 60/39.5; 60/39.52 needed for heating the recycle CO2 circulating ?uid. Fuel (58) Field of Classi?cation Search derived CO2 can be captured and delivered at pipeline pres USPC ...... 60/39.12, 39.182, 39.464, 39.47, 39.5, sure. Other impurities can be captured. 60/39.52, 734, 737, 753, 754, 772, 783, 60/ 805 See application ?le for complete search history. 72 Claims, 12 Drawing Sheets

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440 US 8,596,075 B2 Page 2

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6,871,502 B2 3/2005 Mar1n et al. llgéllrrllder et a1’ Yantovskii et al. , “Computer Exergonomics of Power Plants 6,898,936 B1 5/2005 Ochs et a1‘ W1thout Exhaust ,” Energy Convers. Mgmt., Publ. 1992, vol. 6,910,335 B2 6/2005 Viteri et al. 33, No. 5-8, pp. 405-412. g’? géiltssgender Mathieu et al., “Sensitivity Analysis of the MATIANT Cycle”, 6,993,912 B2 2/2006 Fischer Energy Conversion &-Management, 1999, 1687 1700, vol. 40. 7 007 474 B 1 30006 Ochs et a1‘ Combs, Jr. “An Invest1gat1on of the Supercr1t1cal CO2 Cycle (Feher 730073486 B2 3/2006 Sprouse et a1‘ Cycle) for Shipboard Application,” 1977, Submitted in Partial Eu! 7 £21,063 B2 4/2006 Viteri ?llment 0f the Requirements for the Degree of Ocean Engineer and 7 ,022,168 B2 4/ 2006 Schimkat et al, the Degree of Master of Science in Mechanical Engineering at the 7,043,920 B2 5/ 2006 Viteri et al. Massachusetts Institute of Technology, 148 pages. US 8,596,075 B2 Page 3

(56) References Cited Iantovski et al., “Highly Ef?cient Zero Emission CO2-Based Power Plant” Energy Convers. Mgmt, 1997, Suppl. pp. S 14 l -Sl46, vol. 38. OTHER PUBLICATIONS Wall et al., “A Zero Emission Combustion Power Plant For Enhanced Dostal et al., “A Supercritical Carbon Dioxide Cycle for Next Gen Oil Recovery,” Energy, 1995, pp. 823-828, vol. 20, No. 8. eration Nuclear Reactors,” 2004, (Research Paper) Advanced Nuclear Power Technology Program at MIT, 326 pages. * cited by examiner US. Patent Dec. 3, 2013 Sheet 1 0f 12 US 8,596,075 B2

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FIG. 12 US 8,596,075 B2 1 2 SYSTEM AND METHOD FOR HIGH the ratio of the pres sure at the turbine inlet and the pressure at EFFICIENCY POWER GENERATION USING the turbine outlet) is less than about 12. The ?uid stream can A CARBON DIOXIDE CIRCULATING then be further processed for separation of the components of WORKING FLUID the ?uid stream, Which can include passing the ?uid stream through a heat exchanger. In particular, the circulating ?uid CROSS-REFERENCE TO RELATED (at least a portion of Which may be recycled from the ?uid APPLICATIONS stream) can be passed through the same heat exchanger to heat the circulating ?uid prior to introduction into the com The present patent application claims priority to US. Pro bustor. In such embodiments, it may be useful to operate the visional Patent Application No. 61/299,272, ?led Jan. 28, heat exchanger (e.g., through selection of a loW grade heat 2010, and is a continuation-in-part US. patent application source) such that heat exchanger has only a small temperature Ser. No. 12/714,074, ?led Feb. 26, 2010, Which claims prior difference betWeen the turbine exhaust and the recycle ?uid at ity to US. Provisional Patent Application No. 61/155,755, the hot end of the heat exchanger. ?led Feb. 26, 2009, the disclosures of Which are incorporated In certain aspects, the invention provides poWer production herein by reference in their entirety. systems that can produce poWer at high e?iciency With loW capital cost and also can produce substantially pure CO2 at FIELD OF THE INVENTION pipeline pressure for sequestration. The CO2 also may be recycled into the poWer production system. The present invention is directed to systems and methods The inventive systems and methods are characterized by for generation of poWer, such as electricity, through use of a 20 the ability to use a Wide variety of fuel sources. For example, circulating ?uid to transfer energy generated through high the high e?iciency combustor used according to the invention e?iciency combustion of a fuel. Particularly, the system and can make use of gaseous (e.g., natural or coal derived method can use carbon dioxide as the circulating ?uid. gases), liquid (e.g., hydrocarbons, bitumen) and solid (e.g., coal, lignite, pet-coke) fuels. Even further fuels, as otherWise BACKGROUND OF THE INVENTION 25 described herein, could be used. In other aspects, the methods and systems of the invention It is estimated that fossil fuels Will continue to provide the are particularly useful in that they can exceed the best e?i bulk of the World’s electric poWer requirements for the next ciency of current coal ?red poWer stations that do not provide 100 years While non-carbon poWer sources are developed and for the capture of CO2. Such current poWer stations can pro deployed. Known methods of poWer generation through com 30 vide, at best, about 45% e?iciency (loWer heating value, or bustion of fossil fuels and/or suitable biomass, hoWever, are “LHV”) With 1.7 inches mercury condenser pressure using a plagued by rising energy costs and an increasing production bituminous coal. The present system can exceed such e?i of carbon dioxide (CO2) and other emissions. Global Warm ciency While also delivering CO2 for sequestration or other ing is increasingly seen as a potentially catastrophic conse disposal at required pressures. quence of increased carbon emissions by the developed and 35 In still another aspect, the present invention provides the developing nations. Solar and Wind poWer do not appear ability to reduce the physical siZe and capital cost of a poWer capable of replacing combustion in the near term, generation system compared to current technologies using a and nuclear poWer has dangers associated With both prolif similar fuel. Thus, the methods and systems of the present eration and nuclear Waste disposal. invention can signi?cantly reduce construction costs associ Conventional means of poWer production from fossil fuels 40 ated With poWer production systems. or suitable biomass noW are increasingly being burdened With Still further, the methods and systems of the present inven a requirement for CO2 capture at high pressure for delivery to tion can provide for the recovery of virtually 100% of the CO2 sequestration sites. This requirement is proving di?icult to used and/or produced, especially CO2 derived from carbon ful?ll, hoWever, since present technology only provides for present in the fuel. Particularly, the CO2 can be provided as a very loW thermal e?iciencies for even the best designs for 45 dried, puri?ed gas at pipeline pressure. Moreover, the inven CO2 capture. Moreover, capital costs for achieving CO2 cap tion provides the ability to separately recover other fuel and ture are high, and this results in signi?cantly higher electricity combustion derived impurities for other use and/ or disposal. costs compared to systems that emit CO2 into the atmosphere. In one particular aspect, the present invention is directed to Accordingly, there is an ever groWing need in the art for a method of poWer generation incorporating the use of a systems and methods for high e?iciency poWer generation 50 circulating ?uid, such as CO2. In speci?c embodiments, a alloWing for a reduction in CO2 emission and/or improved method of poWer generation according to the invention can ease of sequestration of produced CO2. comprise introducing a carbon containing fuel, 02, and a C02 circulating ?uid into a transpiration cooled combustor. Spe SUMMARY OF THE INVENTION ci?cally, the CO2 can be introduced at a pressure of at least 55 about 8 MPa (preferably at least about 12 MPa) and a tem The present invention provides methods and system for perature of at least about 200° C. (preferably at least about poWer generation using a high ef?ciency combustor (e.g., a 400° C.). The method further can comprise combusting the transpiration cooled combustor) in combination With a circu fuel to provide a combustion product stream comprising CO2. lating ?uid (e.g., a C02 circulating ?uid). In particular, the Particularly, the combustion product stream can have a tem circulating ?uid can be introduced into the combustor along 60 perature of at least about 8000 C. Further, the method can With a fuel and an oxidant for combustion such that a high comprise expanding the combustion product stream across a pressure, high temperature ?uid stream is produced compris turbine to generate poWer, the turbine having an inlet for ing the circulating ?uid and any combustion products. The receiving the combustion product stream and an outlet for ?uid stream canbe introduced into a poWer generation device, release of a turbine discharge stream comprising CO2. Pref such as a turbine. Advantageously, the ?uid stream can be 65 erably, the pressure ratio of the combustion product stream at maintained at a relatively high pressure during expansion in the inlet compared to the turbine discharge stream at the outlet the turbine such that the pressure ratio across the turbine (i.e., can be less than about 12. In speci?c embodiments, it can be US 8,596,075 B2 3 4 desirable for the CO2 to be introduced into the combustor at a the ?rst heat exchanger being formed of a high temperature pressure of at least about 10 MPa, a pressure of at least about alloy that Withstands a temperature of at least about 9000 C. 20 MPa, a temperature of at least about 400° C., or a tempera The inventive methods also can comprise performing one ture of at least about 700° C. Even further possible processing or more separation steps on the CO2 circulating ?uid stream parameters are described herein. to remove one or more secondary components that are present In some embodiments, the CO2 circulating ?uid can be in the circulating ?uid stream in addition to CO2, as noted introduced to the transpiration cooled combustor as a mixture above. Speci?cally, the one or more secondary components With one or both of the O2 and the carbon containing fuel. In may comprise Water. other embodiments, the CO2 circulating ?uid can be intro The inventive methods also may comprise pressurizing a C02 stream. For example, after expanding of the combustion duced to the transpiration cooled combustor as all or part of a product stream and cooling of the turbine discharge stream, it transpiration cooling ?uid directed through one or more tran can be bene?cial to pressurize the stream for recycle back to spiration ?uid supply passages formed in the transpiration the combustor. Speci?cally, the methods can comprise pass cooled combustor. In speci?c embodiments, the CO2 circu ing the CO2 circulating ?uid stream through one or more lating ?uid can be directed into the combustor only as the compressors (e.g., pumps) to pressurize the CO2 circulating transpiration ?uid. ?uid stream to a pressure of at least about 8 MPa. This further The combustion may be characterized speci?cally by the may comprise passing the CO2 circulating ?uid stream actual combustion temperature. For example, combusting can through a series of at least tWo compressors to pressurize the be carried out at a temperature of at least about l,500° C. In CO2 circulating ?uid stream. In certain embodiments, the other embodiments, combusting can be carried out at a tem 20 CO2 circulating ?uid stream can be pressurized to a pressure perature of about l,600° C. to about 3,300° C. of at least about 15 MPa. Even further pressure ranges may be The invention also may be characterized by the purity of desirable, as otherWise described herein. In other embodi the O2 in the O2 stream. For example, in some embodiments, ments, the pressurized CO2 circulating ?uid stream speci? ambient air may be useful. In speci?c embodiments, hoWever, cally can be provided in a supercritical ?uid state. In some it can be bene?cial to purify the content. For example, 25 embodiments, at least a portion of the CO2 in the pressurized the 02 can be provided as a stream Wherein the molar con CO2 circulating ?uid stream can be introduced into a pressur centration of the O2 is at least 85%. Even further speci?c ized pipeline for sequestration (or other disposal, as already concentrations are described herein. noted above). In speci?c embodiments, the combustion product stream In addition to pressurizing, the inventive methods also can can have a temperature of at least about l,000° C. Moreover, 30 comprise heating the previously cooled CO2 circulating ?uid the combustion product stream can have a pressure that is at stream for introduction back into the combustor (i.e., recy least about 90% of the pressure of the CO2 introduced into the cling of the CO2 circulating ?uid stream). In some embodi combustor or is at least about 95% of the pressure of the CO2 ments, this can comprise heating the pressurized CO2 circu introduced into the combustor. lating ?uid stream to a temperature of at least about 200° C., In some embodiments, the pressure ratio of the combustion 35 at least about 400° C., or at least about 700° C. In certain product stream at the inlet of the turbine compared to the embodiments, the pressurized CO2 circulating ?uid stream turbine discharge stream at the outlet of the turbine can be can be heated to a temperature that is less than the temperature about 1.5 to about 10 or can be about 2 to about 8. Even further of the turbine discharge stream by no more than about 50° C. possible ratios are provided herein. Even further possible temperature ranges are provided herein. The invention may be characterized by the ratio of the 40 Speci?cally, such heating can comprise passing the pressur speci?c materials introduced into the combustion chamber. ized CO2 circulating ?uid stream through the same heat For example, the ratio of CO2 in the CO2 circulating ?uid to exchanger(s) used to cool the turbine discharge stream. Such carbon in the fuel introduced to the combustor, on a molar heating also can comprise input of heat from an external basis, can be about 10 to about 50 or can be about 10 to about source (i.e., other than heat re-captured from the heat 30. Even further possible ratios are provided herein. 45 exchangers). In speci?c embodiments, heating can comprise The invention further may be characterized in that at least the use of heat WithdraWn from an O2 separation unit. Pref a portion of the CO2 in the turbine discharge stream can be erably, this additional heat is introduced at the cold end of the recycled and reintroduced into the combustor. At least a por heat exchanger unit (or, When a series of heat exchangers is tion of the CO2 may be discharged from the system (such as used, prior to the heat exchanger in the series Working over the for sequestration or other disposal), for example through a 50 highest temperature range). pipeline. In certain embodiments, the invention can be characterized In speci?c embodiments, the CO2 in the turbine discharge by nature of the combustion product stream, Which can alloW stream can be in a gaseous state. Particularly, the turbine for the optional implementation of multiple turbines. For discharge stream can have a pressure of less than or equal to example, in some embodiments, the combustion product 7 MPa. 55 stream can be a reducing ?uid comprising one or more com In other embodiments, the inventive methods further can bustible components (e. g., components selected from the comprise passing the turbine discharge stream through at group consisting of H2, CO, CH4, HZS, NH3, and combina least one heat exchanger that cools the turbine discharge tions thereof). This may be controlled by the ratio of O2 to fuel stream and provides a C02 circulating ?uid stream having a used. In some embodiments, the combustion product stream temperature of less than about 200° C. This can be useful for 60 steam may contain fully oxidized components, such as CO2, providing the CO2 circulating ?uid stream under conditions H20, and S02, as Well as the reduced components listed that can facilitate removal of one or more secondary compo above. The actual composition achieved can depend on the nents (i.e., components other than CO2). In speci?c embodi ratio of O2 to fuel used in the feed to the transpiration com ments, this can comprise passing the turbine discharge stream bustor. More speci?cally, the turbine used in such embodi through a series of at least tWo heat exchangers. More spe 65 ments can comprise tWo or more units each having an inlet ci?cally, the ?rst heat exchanger in the series can receive the and an outlet. In speci?c embodiments, the turbine units can turbine discharge stream and reduce the temperature thereof, be operated such that the operating temperature at the inlet of US 8,596,075 B2 5 6 each unit is substantially the same. This can comprise adding sequestration according to the present invention may be trans an amount of O2 to the ?uid stream at the outlet of the ?rst ferred in a manner that is more e?icient and economical than turbine unit (or the preceding turbine unit Where three or more heretofore knoWn. units are used). Provision of the 02 can alloW for combustion The speci?c heat of the recycle CO2 ?uid entering the heat of the one or more combustible components described above, exchanger, ideally at above the critical pressure, is high and Which raises the temperature of the stream prior to entry to the reduces as the temperature rises. It is particularly bene?cial next turbine in the series. This results in the ability to maxi for at least a portion of the heat at the loWest temperature mize the poWer produced from the combustion gases in the levels to be derived from an external source. This could for presence of the circulating ?uid. example be a loW pressure steam supply Which Wouldprovide heat on condensation. In further embodiments this source of In other embodiments, the turbine discharge stream can be heat could be derived from the operation of the air compres an oxidizing ?uid. For example, the turbine discharge stream sors used in the cryogenic air separation plant supplying may comprise an excess amount of 02. oxidant to the combustor in the adiabatic mode With no inter In some embodiments, the invention can be characterized cooling and extraction of the heat of compression With a by the state of the various streams. For example, after the step closed cycle stream of heat transfer ?uid used to provide heat of expanding the combustion product stream across the tur to the recycle CO2 stream. bine, the turbine discharge stream can be in a gaseous state. In one embodiment, a method of poWer generation accord This gas can be passed through at least one heat exchanger to ing to the present invention can comprise the folloWing steps: cool the gaseous turbine discharge stream for separation of introducing a fuel, 02, and a C02 circulating ?uid into a the CO2 from any secondary components. Thereafter, at least 20 combustor, the CO2 being introduced at a pressure of at least a portion of the separated CO2 can be pressurized and trans about 8 MPa and a temperature of at least about 2000 C.; formed into a supercritical ?uid state and again be passed combusting the fuel to provide a combustion product through the same heat exchanger(s) to heat the CO2 for recy stream comprising CO2, the combustion product stream hav cling into the combustor. In speci?c embodiments, the tem ing a temperature of at least about 8000 C.; perature difference betWeen the temperature of the turbine 25 expanding the combustion product stream across a turbine discharge stream entering the heat exchanger (or the ?rst heat to generate poWer, the turbine having an inlet for receiving the exchanger When a series is used) from the expanding step and combustion product stream and an outlet for release of a the temperature of the heated, pressurized, supercritical ?uid turbine discharge stream comprising CO2, Wherein the pres CO2 exiting the same heat exchanger for recycling into the sure ratio of the combustion product stream at the inlet com combustor can be less than about 50° C. 30 pared to the turbine discharge stream at the outlet is less than As noted above, the ?uid stream exiting from the fuel about 12; combustor may comprise the CO2 circulating ?uid as Well as Withdrawing heat from the turbine discharge stream by one or more further components, such as combustion prod passing the turbine discharge stream through a heat exchange ucts. In some embodiments, it can be useful to recycle at least unit to provide a cooled turbine discharge stream; a portion of the CO2 and reintroduce it into the fuel combus 35 removing from the cooled turbine discharge stream one or tor. Thus, the circulating ?uid can be a recycle ?uid. Of more secondary components that are present in the cooled course, CO2 from an external source could be used as the turbine discharge stream in addition to CO2 to provide a circulating ?uid. The turbine exhaust may be cooled in an puri?ed, cooled turbine discharge stream; economizer heat exchanger, and the WithdraWn heat can be compressing the puri?ed, cooled turbine discharge stream used to heat the high pressure recycle C02. The cooled tur 40 With a ?rst compressor to a pressure above the CO2 critical bine exhaust leaving the loW temperature end of the heat pressure to provide a supercritical CO2 circulating ?uid exchanger can contain components derived from the fuel or stream; the combustion process, such as H2O, S02, S03, NO, N02, cooling the supercritical CO2 circulating ?uid stream to a Hg, and HCl. In further embodiments, these components can temperature Where its density is at least about 200 kg/m3 ; be removed from the stream using suitable methods. Other 45 passing the supercritical, high density CO2 circulating ?uid components in this stream may comprise inert gaseous impu through a second compressor to pressurize the CO2 circulat rities derived from the fuel or oxidant such as N2, (Ar), ing ?uid to the pressure required for input to the combustor; and excess 02. These may be removed by separate suitable passing the supercritical, high density, high pressure CO2 processes. In further embodiments, the turbine exhaust must circulating ?uid through the same heat exchange unit such be at a pressure Which is less than the condensing pressure of 50 that the WithdraWn heat is used to increase the temperature of CO2 in the turbine exhaust at the temperature of available the CO2 circulating ?uid; cooling means so that no CO2 liquid phase can form When the supplying an additional quantity of heat to the supercriti turbine exhaust is cooled as this Will alloW e?icient separation cal, high density, high pressure CO2 circulating ?uid so that of Water as liquid from the gaseous CO2 Which Will contain the difference betWeen the temperature of the CO2 circulating the minimal amount of Water vapor to alloW Water to be 55 ?uid exiting the heat exchange unit for recycle to the com condensed. In further embodiments, the puri?ed CO2 can bustor and the temperature of the turbine discharge stream is noW be compressed to produce the high pressure recycle CO2 less than about 500 C.; and circulating ?uid stream together With at least a portion of the recycling the heated, supercritical, high density CO2 circu CO2 in the ?uid representing oxidized carbon derived from lating ?uid into the combustor. carbon in the fuel feed to the combustor, Which can be intro 60 In particular embodiments, the systems and methods may duced into a pressurized pipeline for sequestration. The abil be particularly useful for combining With existing poWer sys ity to transfer CO2 directly from the combustion process into tems and methods (e.g., convention coal ?red poWer stations, a pressurized pipeline With minimal further treatment or com nuclear reactors, and other systems and methods that may pression due to the high pressure of the turbine exhaust stream make use of conventional boiler systems). Thus, in some is a distinct advantage over conventional methods Where CO2 65 embodiments, betWeen the expanding step and the WithdraW is recovered at close to atmospheric pressure (i.e., around 0.1 ing step described above, the inventive methods can comprise MPa) or is emitted to the atmosphere. Moreover, the CO2 for passing the turbine discharge stream through a second heat US 8,596,075 B2 7 8 exchange unit. Such second heat exchange unit can use heat passing the CO2 circulating ?uid stream through a series of from the turbine discharge stream to heat one or more streams at least tWo compressors that increases the pressure of the derived from a steam power system (e.g., a conventional CO2 circulating ?uid to at least about 8 MPa and transforms boiler system, including coal ?red poWer stations and nuclear the CO2 in the circulating ?uid from a gaseous state to a reactor). The thus heated steam streams then can be passed supercritical ?uid state; and through one or more turbines to generate poWer. The streams passing the supercritical CO2 circulating ?uid through the exiting the turbines can be proces sed by cycling back through same series of at least tWo heat exchangers that uses the the components of the conventional poWer system (e.g., the WithdraWn heat to increase the temperature of the CO2 circu boiler). lating ?uid to at least about 200° C. (or, optionally, to a In further embodiments, the inventive method may be char temperature that is less than the temperature of the turbine acteriZed by one or more of the folloWing: discharge stream by no more than about 50° C.). This speci? cooling the turbine discharge stream to a temperature cally may comprise introduction of additional heat from an beloW its Water deW point; external heat source (i.e., a source of heat not derived directly further cooling the turbine discharge stream against an from the passage of the turbine discharge stream through the ambient temperature cooling medium; heat exchanger(s)). condensing Water together With the one or more secondary In further embodiments, the invention may be character components to form a solution comprising one or ore of iZed as providing a high e?iciency method of generating H2SO4, HNO3, HCl, and mercury; poWer from combustion of a carbon containing fuel With no pressuriZing the cooled turbine discharge stream to a pres atmospheric release of CO2. Speci?cally, the method can sure of less than about 15 MPa; 20 comprise the folloWing steps: WithdraWing a product CO2 stream from the supercritical, introducing the carbon containing fuel, 02, and a recycled high density, high pressure CO2 circulating ?uid stream prior CO2 circulating ?uid into a transpiration cooled combustor in to passing through the heat exchange unit; a de?ned stoichiometric ratio, the CO2 being introduced at a using as the fuel a stream of partial combustion products; pressure of at least about 8 MPa and a temperature of at least combusting a carbon containing fuel With O2 in the pres 25 about 200° C.; ence of a C02 circulating ?uid, the carbon containing fuel, combusting the fuel to provide a combustion product 02, and CO2 circulating ?uid being provided in ratios such stream comprising CO2, the combustion product stream hav that the carbon containing fuel is only partially oxidiZed to ing a temperature of at least about 800° C.; produce the partially oxidiZed combustion product stream expanding the combustion product stream across a turbine comprising an incombustible component, CO2, and one or 30 to generate poWer, the turbine having an inlet for receiving the more of H2, CO, CH4, H2S, and NH3; combustion product stream and an outlet for release of a providing the carbon containing fuel, 02, and CO2 circu turbine discharge stream comprising CO2, Wherein the pres lating ?uid in ratios such that the temperature of the partially sure ratio of the combustion product stream at the inlet com oxidiZed combustion product stream is su?iciently loW that pared to the turbine discharge stream at the outlet is less than all of the incombustible component in the stream is in the 35 about 12; form of solid particles; passing the turbine discharge stream through a series of at passing the partially oxidiZed combustion product stream least tWo heat exchangers that WithdraW heat from the turbine through one or more ?lters; discharge stream and provide the CO2 circulating ?uid using the ?lter to reduce the residual amount of incombus stream; tible component to less than about 2 mg/m3 of the partially 40 passing the CO2 circulating ?uid stream through a series of oxidiZed combustion product; at least tWo compressors that increases the pressure of the using coal, lignite, or petroleum coke as the fuel; CO2 circulating ?uid to at least about 8 MPa and transforms providing a particulate fuel as a slurry With CO2; the CO2 in the circulating ?uid from a gaseous state to a In further embodiments, the invention may be described as supercritical ?uid state; relating to a method of poWer generation comprising the 45 passing the CO2 circulating ?uid stream through a separa folloWing steps: tion unit Wherein the stoichiometrically required amount of introducing a carbon containing fuel, 02, and a C02 circu CO2 is recycled and directed to the combustor and any excess lating ?uid into a transpiration cooled combustor, the CO2 CO2 is WithdraWn Without atmospheric release; and being introduced at a pressure of at least about 8 MPa and a passing the recycled CO2 circulating ?uid through the temperature of at least about 200° C.; 50 same series of at least tWo heat exchangers that uses the combusting the fuel to provide a combustion product WithdraWn heat to increase the temperature of the CO2 circu stream comprising CO2, the combustion product stream hav lating ?uid to at least about 200° C. prior to introduction into ing a temperature of at least about 800° C.; the combustor (or, optionally, to a temperature that is less than expanding the combustion product stream across a turbine the temperature of the turbine discharge stream by no more to generate poWer, the turbine having an inlet for receiving the 55 than about 50° C.); combustion product stream and an outlet for release of a Wherein the ef?ciency of the combustion is greater than turbine discharge stream comprising CO2, Wherein the pres 50%, said e?iciency being calculated as the ratio of the net sure ratio of the combustion product stream at the inlet com poWer generated in relation to the total loWer heating value pared to the turbine discharge stream at the outlet is less than thermal energy for the carbon containing fuel combusted to about 12; 60 generate the poWer. passing the turbine discharge stream through a series of at In another aspect, the invention can be described as provide least tWo heat exchangers that WithdraW heat from the turbine a poWer generation system. Speci?cally, a poWer generation discharge stream and provide the CO2 circulating ?uid system according to the invention can comprise a transpira stream; tion cooled combustor, a poWer production turbine, at least removing from the CO2 circulating ?uid stream one or 65 one heat exchanger, and at least one compressor. more secondary components that are present in the circulat In speci?c embodiments, the transpiration cooled combus ing ?uid stream in addition to CO2; tor can have at least one inlet for receiving a carbon-contain US 8,596,075 B2 10 ing fuel, 02, and a C02 circulating ?uid stream. The combus ?uid, and an oxidant; a transpiration cooled combustor hav tor further can have at least one combustion stage that ing at least one combustion stage that combusts the fuel and combusts the fuel in the presence of the CO2 circulating ?uid provides an exhaust ?uid stream at a temperature of at least and provides a combustion product stream comprising CO2 at about 8000 C. and a pressure of at least about 4 MPa (prefer a de?ned pressure (e.g., at least about 8 MPa) and temperature ably at least about 8 MPa); a poWer production turbine having (e.g., at least about 8000 C.). an inlet and an outlet and Wherein poWer is produced as the The poWer production turbine can be in ?uid communica ?uid stream expands, the turbine being designed to maintain tion With the combustor and can have an inlet for receiving the the ?uid stream at a desired pressure such that the ratio of the combustion product stream and an outlet for release of a pressure of the ?uid stream at the inlet versus the outlet is less turbine discharge stream comprising C02. The turbine can be than about 12; a heat exchanger for cooling the ?uid stream adapted to control pressure drop such that the ratio of the leaving the turbine outlet and for heating the CO2 circulating pressure of the combustion product stream at the inlet com ?uid; and one or more devices for separating the ?uid stream pared to the turbine discharge stream at the outlet is less than exiting the heat exchanger into CO2 and one or more further about 12. components for recovery or disposal. In further embodi The at least one heat exchanger can be in ?uid communi ments, the poWer generation system may also comprise one or cation With the turbine for receiving the turbine discharge more devices for delivering at least a portion of the CO2 stream. The heat exchanger(s) can transfer heat from the separated from the ?uid stream into a pressurized pipeline. turbine discharge stream to the CO2 circulating ?uid stream. In speci?c embodiments, a system according to the inven The at least one compressor can be in ?uid communication tion may comprise one or more components as described With the at least one heat exchanger. The compressor(s) canbe 20 herein retro?t With an conventional poWer production system, adapted for pressuriZing the CO2 circulating ?uid stream to a such as a coal ?red poWer station, a nuclear reactor, or the like. desired pres sure. For example, a poWer system could comprise tWo heat In addition to the foregoing, a poWer generation system exchange units (e.g., a primary heat exchange unit and a according to the invention further can comprise one or more secondary heat exchange unit). The primary heat exchange separation devices positioned betWeen the at least one heat 25 unit could be substantially a unit as otherWise described exchanger and the at least one compressor. Such separation herein, and the secondary heat exchange unit could be a unit device(s) can be useful for removal of one or more secondary useful for transferring heat from the turbine discharge stream components present in the CO2 circulating ?uid in addition to to one or more steam streams (e.g., from a boiler associated the CO2. With the conventional poWer production system) to superheat Still further, the poWer generation system can comprise an 30 the steam streams. Thus, a poWer generation system accord O2 separation unit that includes one or more components that ing to the invention may comprise a secondary heat exchange generates heat. Thus, the poWer generation system also can unit located betWeen and in ?uid communication With the comprise one or more heat transfer components that transfers turbine and the primary heat exchange unit. The poWer gen heat from the O2 separation unit to the CO2 circulating ?uid eration system likeWise can comprise a boiler in ?uid com upstream from the combustor. Optionally, the poWer genera 35 munication With the secondary heat exchange unit via at least tion system can comprise an external heat source. This could one steam stream. Still further, the poWer generation system for example be a loW pressure steam supply Which Would can comprise at least one further poWer production turbine provide heat on condensation. The poWer generation system having an inlet for receiving the at least one steam stream thus could include one or more heat transfer components that from the secondary heat exchange unit. Thus, the system may transfers heat from the steam to the CO2 circulating ?uid 40 be described as comprising a primary poWer production tur upstream from the combustor. bine and a secondary poWer production turbine. The primary In further embodiments, a poWer generation system of the poWer production turbine may be the turbine in ?uid commu invention may include one or more of the folloWing: nication With the inventive combustor. The secondary poWer a ?rst compressor adapted to compress the CO2 circulating production turbine may be the turbine in ?uid communication ?uid stream to a pressure that is above the CO2 critical pres 45 With a steam stream, particularly a superheated steam stream sure; that is superheated With heat from the discharge stream from a second compressor adapted to compress the CO2 circu the primary poWer production turbine. Such a system retro?t lating ?uid stream to a pressure required for input to the With one or more components from a convention poWer pro combustor; duction system is described herein, particularly in relation to a cooling device adapted to cool the CO2 circulating ?uid 50 FIG. 12 and Example 2. The use of the terms primary poWer stream to a temperature Where its density is greater than about production turbine and secondary poWer production turbine 200 kg/m3; should not be construed as limiting the scope of the invention one or more heat transfer components that transfers heat and are only used to provide clarity of description. from an external source to the CO2 circulating ?uid upstream In another aspect of the invention an external stream may from the combustor and doWnstream from the second com 55 be heated in the high temperature end of the heat exchanger pressor; by heat transfer from the cooling turbine exhaust stream and, a second combustor located upstream from and in ?uid as a result, the high pressure recycle stream Will leave the heat communication With the transpiration cooled combustor; exchanger and enter the combustor at a loWer temperature. In one or more ?lters or separation devices located betWeen this case, the amount of fuel burned in the combustor may be the second combustor and the transpiration cooled combus 60 increased so that the turbine inlet temperature is maintained. tor; The heating value of the extra fuel burned is equivalent to the a mixing device for forming a slurry of a particulate fuel extra heat load imposed on the heat exchanger. material With a ?uidiZing medium; In some embodiments, the invention can be characterized a milling device for particulariZing a solid fuel. as providing a process plant producing shaft poWer from the In other embodiments, the present invention can provide a 65 circulation of a predominantly CO2 circulating ?uid. In fur poWer generation system that may comprise the folloWing: ther embodiments, the invention provides processes in Which one or more injectors for providing fuel, a C02 circulating certain conditions may be met. In speci?c embodiments, the