초록 ▼

An air separation unit separates air into an oxygen-rich and oxygen-deficient gas. Fuel gas and the oxygen-rich gas are preheated at heat exchangers through which hot flue gas flows. Combustion of the preheated fuel and oxygen-rich gases result in the hot flue gas. The hot flue gas is cooled at the

An air separation unit separates air into an oxygen-rich and oxygen-deficient gas. Fuel gas and the oxygen-rich gas are preheated at heat exchangers through which hot flue gas flows. Combustion of the preheated fuel and oxygen-rich gases result in the hot flue gas. The hot flue gas is cooled at the heat exchangers and flows through a waste heat boiler. Water and/or steam flowing through the waste heat boiler absorbs energy from the cooled flue gas thereby producing heated steam. The heated steam flows through a turbine to produce power. The power is transferred to the air separation unit, thus reducing a power requirement of the air separation unit needed to separate the air.

대표청구항 ▼

We claim: 1. A system for recovering thermal energy produced by an oxygen-enriched combustion furnace in which oxidant and fuel gases are combusted thereby producing flue gas, said system comprising: a) a source of oxidant gas, said oxidant gas having a higher oxygen content than air; b) at least o

We claim: 1. A system for recovering thermal energy produced by an oxygen-enriched combustion furnace in which oxidant and fuel gases are combusted thereby producing flue gas, said system comprising: a) a source of oxidant gas, said oxidant gas having a higher oxygen content than air; b) at least one heat exchanger system adapted to receive the flue gas and at least one of said oxidant gas and the fuel gas, such that the at least one of said oxidant gas and the fuel gas are heated and the flue gas is cooled; c) a waste heat boiler adapted to transfer heat from the flue gas to feedwater flowing therethrough to produce superheated steam; d) a turbine for expansion of the superheated steam therethrough and producing mechanical power therefrom. 2. The system of claim 1, wherein: a) the source of oxygen comprises an air separation unit. 3. The system of claim 1, further comprising a) a shaft operatively connecting said turbine and air separation unit thereby providing at least a portion of said mechanical power to said air separation unit. 4. The system of claim 3, wherein: a) at least about 50% of a power requirement of said air separation unit is provided by said turbine through said shaft. 5. The system of claim 1, wherein: a) at least about 66% of a power requirement of said air separation unit is provided by said turbine through said shaft. 6. The system of claim 1, wherein: a) at least about 79% of a power requirement of said air separation unit is provided by said turbine through said shaft. 7. The system of claim 1, wherein: a) at least about 85% of a power requirement of said air separation unit is provided by said turbine through said shaft. 8. The system of claim 1, wherein: a) said at least one heat exchanger system comprises, i) a first heat exchanger for receiving the flue gas and said oxidant gas, thereby heating said oxidant gas and cooling the flue gas, said first heat exchanger including an outlet for directing said heated oxidant gas to the furnace, and ii) a second heat exchanger for receiving the flue and fuel gases, thereby heating the fuel gas and cooling the flue gas, said second heat exchanger including an outlet for directing the heated fuel gas to the furnace. 9. The system of claim 8, wherein: a) the flue gas is first cooled by said heat exchangers and then further cooled by said boiler; and b) said boiler allows a flow of water and/or steam therethrough such that heat energy from the further cooled flue gas is transferred to the superheated steam at said boiler. 10. The system of claim 1, further comprising: a) a condenser for condensing steam discharged from said turbine; and b) a pump for pressurizing the water condensed at said condenser. 11. The system of claim 8, wherein: a) said heat exchangers are adapted to withstand temperatures such that temperatures of the fuel gas and said oxidant gas heated at said heat exchangers results in a decreased fuel requirement and a decreased oxidant requirement of the furnace, respectively, in comparison to the system of claim 8 when operated without heating said oxidant gas and the fuel gas at said heat exchangers. 12. The system of claim 1, wherein: a) said at least one heat exchanger system comprises a material that substantially resists corrosion under exposure to substantially pure oxygen at a temperature of 700째 C. 13. The system of claim 1, wherein: a) said at least one heat exchanger system includes a heat exchanger having a coating for contact with said oxidant gas; and b) said coating substantially resists corrosion under exposure to substantially pure oxygen at a temperature of 700째 C. 14. The system of claim 1, wherein: a) said at least one heat exchanger system comprises first and second heat exchangers; b) the flue gas and one of said oxidant gas and the fuel gas flows through said first heat exchanger in a same first direction; and c) the flue gas and the other of said oxidant gas and the fuel gas flows through said second heat exchanger in a same second direction. 15. The system of claim 8, wherein: a) said heat exchanger system and said boiler are adapted to cool the flue gas to a temperature of about 150째 C. to about 400째 C. as the flue gas exits said boiler. 16. The system of claim 15, wherein: a) said heat exchanger system and said boiler are adapted to cool the flue gas to a temperature of about 200째 C. to about 300째 C. as the flue gas exits said boiler. 17. The system of claim 1, wherein: a) said at least one heat exchanger system includes i) a first heat exchanger adapted to transfer heat from the flow of flue gas to an intermediate heat transfer fluid, and ii) a second heat exchanger adapted to transfer heat from the intermediate heat transfer fluid to least one of said flow of oxidant gas and the flow of fuel gas. 18. The system of claim 3, wherein: a) more than about 39% a power requirement of said air separation unit is provided by said turbine through said shaft. 19. The system of claim 8, wherein: a) said heat exchangers and boiler are adapted such that a temperature of the flue gas exiting said boiler is less than about 400째 C. ; and b) the temperature of the flue gas exiting said boiler is achieved without dilution of the flue gas by another gas having a temperature less than the temperature of the flue gas. 20. A method for increasing the energy efficiency of an oxygen-enriched combustion furnace, said method comprising the steps of: a) providing oxidant gas and fuel gas, the oxidant gas having an oxygen content higher than air; b) allowing at least one of the oxidant and fuel gases to flow through at least one heat exchanger system thereby heating at least one of the oxidant and fuel gases; c) combusting the heated oxidant and fuel gases in the furnace thereby providing flue gas; d) allowing the flue gas to flow through the at least one heat exchanger system thereby cooling the flue gas as the oxidant and fuel gases are heated; e) allowing feedwater and the flue gas to flow through a waste heat boiler such that heat from the flue gas is transferred to the feedwater thereby producing superheated steam; and f) allowing the superheated steam to be expanded through a turbine thereby producing mechanical power. 21. The method of claim 20, further comprising the step of: a) providing air, wherein said step of providing a flow of oxidant gas is achieved by separating the air with an air separation unit into the oxidant gas and an oxygen-deficient gas, the oxygen-deficient gas having an oxygen content lower than the air. 22. The method of claim 20, further comprising the step of: a) providing the mechanical power to the air separation unit. 23. The method of claim 20, further comprising the steps of: a) selecting as the at least one heat exchanger system a first heat exchanger and a second heat exchanger; b) allowing one of the oxidant and fuel gases to flow through the first heat exchanger; c) allowing the other of the oxidant and fuel gases to flow through the second heat exchanger; and d) allowing the flue gas to flow through the first and second heat exchangers thereby heating the oxidant and fuel gases and cooling the flue gas and heating oxidant and fuel gases. 24. The method of claim 20, further comprising: a) heating at least one of the oxidant and fuel gases at the at least one heat exchanger to a temperature of from about 200째 C. to about 800째 C. 25. The method of claim 20, wherein: a) the flow of flue gas from the furnace has a temperature of greater than about 1,250째 C. 26. The method of claim 20, wherein: a) the flow of flue gas is cooled by the at least one heat exchanger system such that the flow of flue gas entering the waste heat boiler has a temperature of from about 300째 C. to about 1,500째 C. 27. The method of claim 23, wherein: a) each of the heat exchangers comprises a material that substantially resists corrosion under exposure to oxygen at a surface temperature of 700째 C. 28. The method of claim 21, further comprising the step of: a) transferring the mechanical power from the turbine to the air separation unit with a shaft thereby supplying at least about 50% of a power requirement of the air separation unit needed for separating the air into the oxidant and oxygen-deficient gases. 29. The method of claim 21, further comprising the step of: a) transferring the mechanical power from the turbine to the air separation unit with a shaft thereby supplying at least about 66% of a power requirement of the air separation unit needed for separating the air into the oxidant and oxygen-deficient gases. 30. The method of claim 21, further comprising the step of: a) transferring the mechanical power from the turbine to the air separation unit with a shaft thereby supplying at least about 79% and up to about 67% of a power requirement of the air separation unit needed for separating the air into the oxidant and oxygen-deficient gases. 31. The method of claim 21, further comprising the step of: a) transferring the mechanical power from the turbine to the air separation unit with a shaft thereby supplying at least about 85% of a power requirement of the air separation unit needed for separating the air into the oxidant and oxygen-deficient gases. 32. The method of claim 21, further comprising the step of: a) transferring the mechanical power from the turbine to the air separation unit with a shaft thereby supplying more than 50% of a power requirement of the air separation unit needed for separating the air into the oxidant and oxygen-deficient gases. 33. The method of claim 23, wherein heating of the oxidant and fuel gases decreases a fuel gas requirement and an oxidant gas requirement of the furnace, respectively, in comparison to when the method of claim 27 is operated without heating the oxidant and fuel gases at the heat exchangers. 34. The method of claim 20, wherein: a) a temperature of the flue gas exiting said boiler is less than about 400째 C.; and b) the temperature of the flue gas exiting said boiler is achieved without dilution of the flue gas by another gas having a temperature less than the temperature of the flue gas. 35. A system for increasing the energy efficiency of an oxygen-enriched combustion furnace in which oxidant gas and fuel gas are combusted thereby producing a hot flue gas, said system comprising: a) an air separation unit adapted to provide a flow of oxidant gas, said oxidant gas having a higher oxygen content than air, said air separation unit having a power requirement x needed for providing the flow of oxidant gas; b) at least one heat exchanger system adapted to receive a flow of hot flue gas and at least one of said flow of oxidant gas and the flow of fuel gas, thereby heating at least one of said flow of oxidant gas and the flow fuel gas and cooling the hot flow of flue gas; c) a waste heat boiler adapted to absorb heat energy from the cooled flow of flue gas and produce superheated steam and further cooling the cooled flow of flue gas; d) a turbine adapted to allow expansion of the superheated steam therethrough thereby producing mechanical power therefrom; and e) a shaft adapted to transfer the mechanical power from said turbine to said air separation unit, wherein said air separation unit, said at least one heat exchanger, said waste heat boiler, said turbine, and said shaft are adapted such that the mechanical power provides at least about 39% of said power requirement x. 36. A method for recovering energy from a combustion furnace that combusts oxygen-rich gas and fuel to gas to produce a hot flue gas, said method comprising the steps of: a) separating a source of air with an air separation unit into oxygen-enriched gas and oxygen-deficient gas, the oxygen-rich gas having an oxygen content higher than the air; the oxygen-deficient gas having an oxygen content lower than the air; b) providing a fuel gas; c) providing first and second heat exchangers; d) allowing one of the fuel gas and flue gas to flow through the first heat exchanger thereby providing heated fuel gas and cooled flue gas; e) allowing the other of the oxygen-rich gas and cooled flue gas to flow through the second heat exchanger thereby heating the oxygen-rich gas and further cooling the cooled flue gas, the further cooled flue gas having a temperature lower than the cooled flue gas; f) combusting the heated oxygen-rich gas and the heated fuel gas in the combustion furnace thereby providing the hot flue gas; g) allowing the further cooled flue gas to flow through a waste heat boiler such that heat is absorbed from the further cooled flue gas to produce superheated steam; h) allowing the superheated steam to be expanded through a turbine thereby producing mechanical power; and j) transferring the mechanical power to the air separation unit thereby decreasing more than 50% of a power requirement of the air separation unit that is needed to separate the air.