초록 ▼

There is disclosed a method and system for pressurizing a reductant solution from a reductant storage device and superheating the pressurized reductant solution. The superheated pressurized reductant solution at least partially decomposes in the heat exchanger and/or a decomposition chamber before i

There is disclosed a method and system for pressurizing a reductant solution from a reductant storage device and superheating the pressurized reductant solution. The superheated pressurized reductant solution at least partially decomposes in the heat exchanger and/or a decomposition chamber before it is released into an exhaust system. The at least partially decomposed reductant solution is delivered to the exhaust system upstream of the SCR catalyst.

대표청구항 ▼

1. A system comprising: an internal combustion engine;an exhaust conduit fluidly coupled to the internal combustion engine;a selective catalytic reduction (SCR) catalyst fluidly coupled to the exhaust conduit;a storage device for storing a reductant solution;a reductant solution delivery system defi

1. A system comprising: an internal combustion engine;an exhaust conduit fluidly coupled to the internal combustion engine;a selective catalytic reduction (SCR) catalyst fluidly coupled to the exhaust conduit;a storage device for storing a reductant solution;a reductant solution delivery system defining a flowpath for delivering superheated reductant to the exhaust conduit at a location upstream of the SCR catalyst, wherein the reductant solution delivery system includes: a decomposition chamber connected to the exhaust conduit upstream of the SCR catalyst;an orifice along the flowpath opening into the decomposition chamber;a heating device in the flowpath upstream of the orifice; anda metering device in the flowpath upstream of the heating device, wherein the metering device regulates flow of pressurized reductant solution from the storage device to the heating device, wherein the heating device is operable to superheat the pressurized reductant solution for passage through the orifice, wherein the superheated pressurized reductant solution expands through the orifice and flash vaporizes to at least partially decompose in the decomposition chamber before entering the exhaust conduit. 2. The system of claim 1, further including a high pressure pump flow coupled to the storage device, wherein the high pressure pump is operable to pressurize the reductant solution from the storage device for delivery to the metering device. 3. The system of claim 1, further including a valve in the flowpath between the orifice and the heating device to regulate flow of pressurized superheated reductant solution through the orifice. 4. The system of claim 1, further comprising an exhaust gas recirculation (EGR) system connecting the exhaust conduit to an intake system of the internal combustion engine. 5. The system of claim 4, wherein the heating device includes a heat exchanger fluidly connected to the EGR system and fluidly connected to the reductant solution flowpath between the orifice and the metering device. 6. The system of claim 5, wherein the EGR system includes a reductant heating portion connected to the heat exchanger, a bypass portion bypassing the heat exchanger, and a bypass valve operable to control flow of exhaust gas to the heat exchanger and to the bypass portion. 7. The system of claim 5, wherein the heat exchanger is operable to superheat the reductant solution to a temperature of at least 100° Celsius. 8. The system of claim 1, wherein the reductant solution is a urea solution that at least partially dissolves in the decomposition chamber to form NH4 ions. 9. The system of claim 1, wherein the reductant solution is a mixture of water and urea. 10. An apparatus comprising: a storage device for storing a urea solution;a pumping device fluidly connected to the urea solution in the storage device;a metering device fluidly connected to the pumping device;a heating device fluidly connected to the metering device, wherein the heating device is operable to superheat a flow of pressurized urea solution regulated by the metering device; andan orifice fluidly connected to the heating device that opens into a decomposition chamber, wherein the superheated pressurized urea solution expands through the orifice and at least partially decomposes in the decomposition chamber, wherein the decomposition chamber is connectable to an exhaust conduit upstream of a selective catalytic reduction catalyst. 11. The apparatus of claim 10, further including a valve in the flowpath between the orifice and the heating device to regulate flow of pressurized superheated urea solution through the orifice. 12. The apparatus system of claim 10, wherein the heating device includes a heat exchanger fluidly connected to the metering device to receive urea solution therethrough, the heat exchanger further being configured for connection to an exhaust gas recirculation system to fluidly receive exhaust gas that that supplies a heat source for superheating the pressurized urea solution. 13. The apparatus of claim 12, wherein the heat exchanger is operable to superheat the urea solution to a temperature of at least 100° Celsius. 14. The apparatus of claim 10, wherein the urea solution at least partially decomposes in the decomposition chamber to form NH4 ions. 15. The apparatus of claim 10, wherein the urea solution is a mixture of water and urea. 16. A method, comprising: pressurizing a reductant solution from a reductant solution storage device;superheating the pressurized reductant solution;delivering the superheated reductant solution through an orifice; andexpanding the superheated reductant solution in a decomposition chamber connected to the orifice to decompose the superheated reductant solution and form reductant in the decomposition chamber; andreleasing the reductant from the decomposition chamber into an exhaust system upstream from a selective catalytic reduction catalyst. 17. The method of claim 16, wherein pressurizing the reductant solution includes pumping the reductant solution from the reductant solution storage device with a high pressure pump. 18. The method of claim 17, further comprising metering a flow of the pressurized reductant solution from the pumping device before superheating the reductant solution. 19. The method of claim 16, wherein superheating the pressurized reductant solution includes passing the pressurized reductant solution through a heat exchanger connected to an exhaust gas recirculation system, wherein the exhaust gas recirculation (EGR) system provides heat for superheating the reductant solution. 20. The method of claim 19, further comprising opening an EGR valve and a bypass valve of the EGR system to direct exhaust gas to the heat exchanger. 21. The method of claim 19, wherein superheating the pressurized reductant solution includes raising a temperature of the pressurized reductant solution to at least 100° Celsius. 22. The method of claim 16, further comprising decomposing the superheated pressurized reductant solution in the decomposition chamber to form NH4 ions before releasing the reductant into the exhaust system. 23. A method, comprising: pressurizing a reductant solution from a reductant solution storage device;superheating the pressurized reductant solution, such that at least a portion of the reductant solution at least partially decomposes in solution to form at least one of NH3 gas and NH4+ ions;delivering the partially decomposed reductant solution through a metering device; andexpanding the partially decomposed reductant solution in an exhaust stream at a location upstream of a selective catalytic reduction (SCR) catalyst. 24. The method of claim 23, wherein there is a decomposition chamber connected to the metering device and further comprising: decomposing the superheated reductant solution to form reductant in the decomposition chamber; andreleasing the reductant from the decomposition chamber into the exhaust stream upstream from the SCR catalyst. 25. The method of claim 23, wherein pressurizing the reductant solution includes pumping the reductant solution from the reductant solution storage device with a high pressure pump. 26. The method of claim 25, further comprising metering a flow of the pressurized reductant solution from the pumping device before superheating the reductant solution. 27. The method of claim 23, wherein the partially decomposed reductant solution is allowed to cool below superheated temperature prior to injection into the exhaust stream. 28. The method of claim 23, wherein superheating the pressurized reductant solution includes passing the pressurized reductant solution through a heat exchanger connected to an exhaust gas recirculation (EGR) system, wherein the EGR system provides heat for superheating the reductant solution. 29. The method of claim 28, further comprising opening an EGR valve and a bypass valve of the EGR system to direct exhaust gas to the heat exchanger. 30. The method of claim 28, wherein superheating the pressurized reductant solution includes raising a temperature of the pressurized reductant solution to at least 100° Celsius. 31. The method of claim 23, further comprising decomposing the superheated pressurized reductant solution in a decomposition chamber to form NH4 ions before releasing the reductant into the exhaust system. 32. An apparatus comprising: a storage device for storing a urea solution;a pumping device fluidly connected to the urea solution in the storage device;a heating device fluidly connected to the pumping device, wherein the heating device is operable to superheat the flow of pressurized urea solution from the pumping device and at least partially decompose the reductant solution in solution to form at least one of NH3 gas and NH4+ ions;a metering device fluidly connected to the heating device to receive at least partially decomposed urea solution from the heating device; andan orifice fluidly connected to the metering device that opens into an exhaust system at a position upstream of a selective catalytic reduction (SCR) catalyst to release at least partially decomposed urea solution into the exhaust system. 33. The apparatus of claim 32, further comprising a decomposition chamber connected to the orifice between the orifice and the exhaust system, wherein at least partially decomposed reductant solution is injected from the orifice into the decomposition chamber for further decomposition before release into the exhaust system. 34. The apparatus of claim 32, wherein the heating device includes a heat exchanger to receive urea solution therethrough, the heat exchanger further being configured for connection to an exhaust gas recirculation system to fluidly receive exhaust gas that that supplies a heat source for superheating the pressurized urea solution. 35. The apparatus of claim 34, wherein the heat exchanger is operable to superheat the urea solution to a temperature of at least 100° Celsius. 36. The apparatus of claim 32, wherein the urea solution is a mixture of water and urea.