초록 ▼

The disclosure provides methods and systems for recovering thermal energy from heated exhaust gases. The methods and systems have particular use in conjunction with combustion source effluent/exhaust streams. The methods of energy recovery increase life expectancy of various equipment, while reducin

The disclosure provides methods and systems for recovering thermal energy from heated exhaust gases. The methods and systems have particular use in conjunction with combustion source effluent/exhaust streams. The methods of energy recovery increase life expectancy of various equipment, while reducing operating and maintenance costs for economic recovery of enthalpy from heated process streams. In certain aspects, the methods of recovering thermal energy include providing a heated low pressure effluent stream. A high velocity stream is injected into an entrainment zone to form a high velocity jet which entrains the heated effluent stream. The momentum of the system is conserved and a mixed stream is pressurized and recirculated to a burning zone of a combustion source. The methods also reduce pollutant emissions.

대표청구항 ▼

1. A method of recovering enthalpy from a combustion source, the method comprising: reacting oxygen and a fuel in a direct-fire combustion reaction zone of a furnace to generate a heated effluent stream that exits the furnace;entraining at least a portion of said heated effluent stream in a high vel

1. A method of recovering enthalpy from a combustion source, the method comprising: reacting oxygen and a fuel in a direct-fire combustion reaction zone of a furnace to generate a heated effluent stream that exits the furnace;entraining at least a portion of said heated effluent stream in a high velocity jet stream to form a mixed stream, wherein said entraining occurs external to said direct-fire combustion reaction zone of said furnace, and said high velocity jet stream comprises oxygen or fuel;pressurizing said mixed stream; andintroducing said pressurized mixed stream into said direct-fire combustion reaction zone of said furnace to recirculate at least a portion of the heated effluent stream, thereby recovering at least a portion of the enthalpy contained in said heated effluent stream, wherein said introducing of said pressurized mixed stream into said direct-fire combustion reaction zone results in a radiative homogenous combustion mode with flameless combustion of said oxygen and said fuel in said direct-fire combustion reaction zone. 2. The method of claim 1, wherein said portion of the enthalpy is at least 50% of the enthalpy of said heated effluent stream. 3. The method of claim 1, wherein said pressurizing comprises passing said mixed stream through a venturi-shaped flow passage having a reduced diameter. 4. The method of claim 1, wherein said pressurizing increases a pressure of the mixed stream to at least five times the pressure of said heated effluent stream when exiting said reaction zone. 5. The method of claim 1, wherein the reacting of the oxygen and the fuel is done at a first pressure and said pressurizing increases a pressure of said mixed stream to a level greater than or equal to said first pressure and said pressurized mixed stream introduced into said direct-fire combustion reaction zone of said furnace raises a temperature of the reacting oxygen and fuel to above an auto-ignition temperature of the fuel. 6. The method of claim 1, wherein said high velocity jet stream comprises oxygen. 7. The method of claim 6, wherein said oxygen for said reacting and said oxygen of said high velocity jet stream are substantially pure oxygen. 8. The method of claim 1, wherein said high velocity jet stream is a first jet stream that comprises oxygen and said mixed stream is a first mixed stream, wherein said method further comprises entraining at least a portion of said heated effluent stream in a second high velocity jet stream that comprises fuel and that forms a second mixed stream which undergoes said pressurizing and is then introduced to said direct-fire combustion reaction zone where it is mixed with said first mixed stream comprising oxygen. 9. The method of claim 1, wherein one or more pollutants are reduced from a level of pollutants otherwise generated in a comparative combustion reaction not having the high velocity jet stream and the recirculated mixed stream. 10. The method of claim 1, wherein a second stream comprising oxygen is introduced into said pressurized mixed stream prior to said introducing to said direct-fire combustion reaction zone. 11. The method of claim 1, wherein said portion of said heated effluent stream entrained in the mixed stream by the high velocity jet stream and introduced into said direct-fire combustion reaction zone of said furnace is at least 50% of the volume of the effluent stream that exits said furnace. 12. The method of claim 1, wherein a mass flow rate of said high velocity jet stream is expressed by m.x=Ce×m.0×xd0×(ρ∞ρ0)12, where Ce is a coefficient of expansion, {dot over (m)}x is the mass flow rate at distance x measured from the virtual origin of a nozzle, d0 is the jet diameter at the exit of the nozzle, {dot over (m)}0 is the jet mass flow rate at the nozzle exit; ρ0 and ρ∞ are the respective densities of the jet at the exit of the nozzle and at a distance x from the nozzle. 13. The method of claim 1, wherein said high velocity jet stream has a jet expansion half-angle of 10° to 15°. 14. The method of claim 13, wherein said high velocity jet stream has a jet expansion half-angle of 12°. 15. The method of claim 1, wherein at least a portion of said high velocity jet stream is pre-heated by a recuperator and/or regenerator. 16. A method of improving energy efficiency of a combustion source, the method comprising: reacting oxygen and a fuel in a direct-fire combustion reaction zone of a furnace to generate a heated effluent stream having a flow rate ranging from greater than or equal to about 10,000 actual ft3/min (about 285 m3/min) to about 600,000 acfm (about 17,000 m3/min) that exits the furnace;entraining greater than or equal to about 50 vol. % of said heated effluent stream formed in said direct-fire combustion reaction zone in a high velocity oxygen-containing jet to form a pressurized mixed stream in a mixing chamber having a volume permitting a residence time of at least 0.1 seconds for said heated effluent stream external to said direct-fire combustion reaction zone of said furnace; andreturning said mixed stream to said direct-fire combustion reaction zone of said furnace by introducing said mixed stream into said direct-fire combustion reaction zone. 17. The method of claim 16, wherein said high velocity oxygen-containing jet comprises substantially pure oxygen. 18. A method of recovering thermal energy comprising: providing a process effluent stream having a first temperature and a first pressure, wherein said process effluent stream is formed by reacting oxygen and a fuel in a direct-fire combustion source;creating a high velocity jet in a mixing chamber downstream from and in fluid communication with said direct-fire combustion source that entrains a portion of said process effluent stream into said high velocity jet to form a mixed stream, wherein said mixing chamber has a volume permitting a residence time of at least 0.1 seconds for said process effluent stream; andpassing at least a portion of said mixed stream through a collection duct that increases pressure of the mixed stream, so that the mixed stream has a second temperature and a second pressure and is delivered to said direct-fire combustion source, wherein said first temperature is greater than said second temperature and said first temperature is at least about 500° F. (about 260° C.), and said second pressure is at least five times said first pressure. 19. The method of claim 18, wherein said high velocity jet comprises oxygen or a fuel. 20. The method of claim 18, wherein said first pressure is less than or equal to 1 inch of water column (about 250 Pa) and said second pressure of the mixed stream is greater than or equal to about 20 inches of water column (about 5 kPa). 21. A method of recovering enthalpy from a combustion source, the method comprising: reacting oxidant and fuel in a direct-fire combustion reaction zone of a furnace to generate a heated effluent stream that exits the furnace;entraining at least a portion of the heated effluent stream in a high velocity jet stream to form a mixed stream external to said direct-fire combustion reaction zone, wherein said high velocity jet comprises fuel;pressurizing said mixed stream; andintroducing said pressurized mixed stream into said direct-fire combustion reaction zone to recirculate at least a portion of the heated effluent stream, thereby recovering at least a portion of the enthalpy contained in said heated effluent stream, wherein said introducing of said pressurized mixed stream into said direct-fire combustion reaction zone results in a temperature of said pressurized mixed stream being above an auto-ignition temperature for the fuel to result in a radiative homogenous combustion mode in said direct-fire combustion reaction zone of the furnace. 22. The method of claim 21, wherein said radiative homogenous combustion mode results in flameless combustion of said oxygen and said fuel in said direct-fire combustion reaction zone of said furnace. 23. The method of claim 21, wherein said high velocity jet stream is a first jet stream that comprises fuel and said pressurized mixed stream is a first mixed stream, wherein the method further comprises entraining at least a portion of said heated effluent stream in a second high velocity jet stream that comprises oxygen and that forms a second mixed stream which undergoes said pressurizing and is then introduced to said direct-fire combustion reaction zone where it is mixed with said first mixed stream comprising fuel.