METHOD FOR EXHAUST GAS AFTERTREATMENT AND COMBUSTION SYSTEM

Abstract

In a method for exhaust gas aftertreatment, in which an exhaust gas to be aftertreated, which is produced during combustion of a fuel, is treated with a reducing agent. A constituent of the fuel is hereby also used as a constituent of the reducing agent, with the constituent of the fuel which is also used as a constituent of the reducing agent being hydrogen. The hydrogen is produced from water, and the reducing agent is a mixture of hydrogen and ammonia.

Claims

1.-13. (canceled)

14. A method for exhaust gas aftertreatment, comprising: producing hydrogen from water; producing a reducing agent from a mixture of produced hydrogen and ammonia; and treating exhaust gas produced during combustion of a fuel with the reducing agent, with produced hydrogen also forming a constituent of the fuel.

15. The method of claim 14, wherein the fuel is a gas mixture of hydrogen and a hydrocarbon gas.

16. The method of claim 14, wherein the reducing agent has a hydrogen-to-ammonia ratio equal to 1 or less than 1.

17. The method of claim 14, wherein the exhaust gas is reduced using the reducing agent.

18. The method of claim 14, wherein the exhaust gas is selectively catalytically reduced using the reducing agent and a catalyst.

19. The method of claim 14, wherein the exhaust gas comprises nitrogen oxides, further comprising denitrifying the exhaust gas during the exhaust gas aftertreatment.

20. The method of claim 14, further comprising conducting produced hydrogen to a common store, and supplying produced hydrogen as constituent for the fuel and constituent for the reducing agent from the common store.

21. The method of claim 14, wherein the hydrogen is produced by electrolysis.

22. A combustion system, comprising: a combustion chamber for combusting a fuel to thereby produce an exhaust gas; a store connected to the combustion chamber and containing a constituent of the fuel for supply of the constituent to the combustion chamber; and a reducing chamber connected to the store to also receive from the store the constituent of the fuel as one constituent of a reducing agent for aftertreatment of the exhaust gas.

23. The combustion system of claim 22, further comprising an internal combustion machine, said combustion chamber being a component of the internal combustion machine.

24. The combustion system of claim 23, wherein the internal combustion machine is a gas turbine or an internal combustion engine.

25. The combustion system of claim 22, wherein the reaction chamber contains a catalyst to carry out a selective catalytic reduction.

26. The combustion system of claim 22, further comprising an electrolyzer configured to produce the constituent of the fuel.

27. The combustion system of claim 22, wherein the constituent of the fuel and the reducing agent is hydrogen.

28. The combustion system of claim 22, wherein the reducing agent includes hydrogen as the one constituent and ammonia as another constituent.

29. The combustion system of claim 28, wherein the reducing agent has a hydrogen-to-ammonia ratio equal to 1 or less than 1.

30. The combustion system of claim 28, wherein the aftertreatment of the exhaust gas comprises an exhaust gas denitrification.

Description

[0048] In the drawings:

[0049] FIG. 1 is a combustion system with a gas turbine and an electrolyzer, and

[0050] FIG. 2 is a further combustion system with an internal combustion engine.

[0051] FIG. 1 shows schematically a combustion system 2 with an internal combustion machine 4. In the present exemplary embodiment, the internal combustion machine 4 is configured as a gas turbine.

[0052] The gas turbine comprises an expander 6 and a compressor 8. The gas turbine also comprises a combustion chamber 10 which is arranged between the expander 6 and the compressor 8. The combustion chamber 10 is equipped with a plurality of ignition plugs 12 of which one is shown by way of example in FIG. 1.

[0053] Furthermore, the combustion system 2 has an air inlet duct 14 which is connected to the compressor 8. Air can be conducted through the air inlet duct 14 into the gas turbine, particularly into the compressor 8.

[0054] Furthermore, the combustion system 2 has a generator 16. The generator 16 and the gas turbine have a common shaft 18 by means of which the generator 16 is driveable.

[0055] Furthermore, in the combustion system 2, a reducing chamber 20 is provided in which a catalyst 22 is arranged. The catalyst 22 has a carrier made of ceramics, on which a catalytically active layer which is made of a noble metal, for example platinum (not shown in FIG. 1), is arranged.

[0056] The reducing chamber 20 is connected to an exhaust gas duct 24 through which a gas/gas mixture, in particular an exhaust gas, can be conducted away. Furthermore, the reducing chamber 20 is connected via a connecting duct 26 to the gas turbine, in particular to the expander 6.

[0057] Furthermore, the combustion system 2 comprises a store 28 for hydrogen, a store 30 for an ammonia solution and a store 32 for methane. The stores 28, 30, 32 are each configured as pressure vessels.

[0058] Furthermore, the store 32 for methane is connected via a supply line 34 to the combustion chamber 10. The store 30 for the ammonia solution is connected via a further supply line 34 to the reducing chamber 20. In addition, the store 28 for hydrogen is connected via a first supply line 34 to the combustion chamber 10, via a second supply line 34 to the reducing chamber 20 and via a third supply line 34 to an electrolyzer 36. The aforementioned supply lines 34 are each equipped with an electrically controllable valve 38.

[0059] The electrolyzer 36 comprises an electrolysis vessel 40 and two electrodes arranged in the electrolysis vessel, an anode 42 and a cathode 44. The anode 42 and the cathode 44 are connected to a DC voltage source 46. Furthermore, the electrolyzer 36 comprises a water inlet line 48.

[0060] The combustion system 2 is also equipped with a control unit 50 by means of which the valves 38 of the supply lines 34 are controllable.

[0061] Air is conducted through the air inlet duct 14 into the gas turbine, particularly into the compressor 8. An inflow direction 52 of the air is indicated in FIG. 1 with an arrow.

[0062] In the compressor 8, the air is compressed, wherein a temperature of the air increases. The heated, compressed air flows into the combustion chamber 10 where a fuel is fed into it.

[0063] In the present exemplary embodiment, the fuel is a gas mixture with two constituents, methane and hydrogen. The methane is fed from the store 32 for methane into the combustion chamber 10. Accordingly, the hydrogen is fed in from the store 28 for hydrogen into the combustion chamber 10.

[0064] A mixture of the fuel and the air (fuel-air mixture) is ignited by the ignition plugs 12. Subsequently, the fuel burns with oxygen fed in from the air. Herein, a hot exhaust gas is produced which comprises, inter alia, sulfur dioxide and a variety of nitrogen oxides. Due to the heat arising during the combustion, the exhaust gas expands.

[0065] The expanding exhaust gas flows into the expander 6 and powers it. By means of the common shaft 18, the expander 6 powers the generator 16.

[0066] Subsequently, the exhaust gas flows via the connecting duct 26 into the reducing chamber 20. Here, the exhaust gas is treated/aftertreated with a reducing agent.

[0067] In the present exemplary embodiment, the reducing agent is a further gas mixture with two constituents, hydrogen and ammonia. Therefore the hydrogen is used both as a constituent of the fuel and also as a constituent of the reducing agent. The ammonia is fed from the store 30 for ammonia into the reducing chamber 20. Accordingly, the hydrogen is fed in from the store 28 for hydrogen into the reducing chamber 20.

[0068] Herein, the hydrogen-to-ammonia ratio of the further gas mixture is equal to 0.5. This means that a particle count of the ammonia in the reducing agent is double the amount of a particle count of the hydrogen in the reducing agent.

[0069] In the aftertreatment of the exhaust gas, it is selectively catalytically reduced making use of the reducing agent and the catalyst 22. Primarily, nitrogen oxides are reduced, whereas unwanted side reactions, for example, an oxidation of sulfur dioxide to sulfur trioxide remain absent. This means that the exhaust gas is denitrified.

[0070] Following its aftertreatment, the exhaust gas flows out of the reducing chamber 20 via the exhaust gas outlet duct 24. An outflow direction 54 of the exhaust gas is indicated in FIG. 1 with an arrow. The hydrogen which comes into use as a constituent of the fuel/reducing agent is produced from water. The production of the hydrogen takes place herein with the aid of the electrolyzer 36. For this purpose, water (with the addition of acid or alkali) is fed into the electrolysis vessel 40 of the electrolyzer 36 via the water inlet line 48.

[0071] In the electrolyzer 36, electrolysis takes place wherein the water fed in is broken down into hydrogen and oxygen with the aid of the DC voltage source 46 (water electrolysis). For the electrolysis, the DC voltage source 46 uses energy peaks which occur during power generation from renewable energy sources, for example, wind or solar energy. The hydrogen obtained in this way is fed, via the supply line 34 which connects the electrolyzer 36 to the store 28 for hydrogen, into said store 28 so that it is filled (again).

[0072] The following description is essentially restricted to the differences from the aforementioned exemplary embodiment to which reference is made in relation to features and functions that remain the same. Substantially the same or mutually corresponding elements are fundamentally identified with the same reference signs and features that are not mentioned are adopted in the following exemplary embodiment without being described again.

[0073] FIG. 2 shows schematically a further combustion system 2 with an internal combustion machine 4. In the present exemplary embodiment, the internal combustion machine 4 is configured as an internal combustion engine, in particular as a hydrogen-powered internal combustion engine.

[0074] The internal combustion engine comprises a combustion chamber 10 in which a plurality of ignition plugs 12 are arranged. FIG. 2 shows one of the ignition plugs 12 by way of example.

[0075] Furthermore, the internal combustion engine has a piston 56. That is, the internal combustion engine is a piston engine. Furthermore, the internal combustion engine comprises a connecting rod 58 which is connected to the piston 56 and to a crankshaft 60. The crankshaft 60 is drivable by means of the piston 56 and the connecting rod 58.

[0076] Furthermore, the combustion system 2 comprises an air inlet duct 14 with an inlet valve 62. With the aid of the inlet valve 62, a conduction of a gas/gas mixture, in particular a fuel-air mixture into the combustion chamber 10 is controllable. Furthermore, the combustion system 2 comprises a connecting duct 26 by means of which the combustion chamber 10 is connected to a reducing chamber 20. The connecting duct 26 is equipped with an outlet valve 64. With the aid of the outlet valve 64, a conduction out of a gas/gas mixture, in particular an exhaust gas, is controllable.

[0077] Furthermore, the combustion system 2 comprises a store 28 for hydrogen. This store 28 is connected via a first connecting line 34 to the air inlet duct 14, in particular on the inlet side of the inlet valve 62. The combustion chamber 10 is thus suppliable via the air inlet duct 14 with air and additionally with hydrogen. Said store 28 is connected via a second connecting line 34 to the reducing chamber 20.

[0078] In an opened state of the inlet valve 62, the fuel-air mixture is fed into the combustion chamber 10. The fuel-air mixture is drawn in with the aid of the piston 56, whilst the piston 56 is moved away from the inlet valve 62 or the outlet valve 64 (downwardly in the drawing). The outlet valve 64 is herein closed.

[0079] The air of the fuel-air mixture flows through the air inlet duct 14 into the combustion chamber 10. An inflow direction 52 of the air is represented in FIG. 2 by an arrow. During its flow through the air inlet duct 14, the air is mixed with gaseous hydrogen as fuel, which is fed in from the store 28 into the air inlet duct 14. In the present exemplary embodiment, the fuel has a single constituent, specifically the gaseous hydrogen.

[0080] Next, the inlet valve 62 is closed. The piston 56 moves toward the inlet valve 62 and the outlet valve 64 (upwardly in the drawing) and thereby compresses the fuel-air mixture, wherein a temperature of the fuel-air mixture rises.

[0081] The fuel-air mixture is ignited with the aid of the ignition plugs 12. Subsequently, the fuel burns with oxygen from the air. Herein, a hot exhaust gas is produced. Due to the heat arising during the combustion, the exhaust gas expands so that the piston 56 is moved away from the inlet valve 62 and the outlet valve 64 again. The exhaust gas therefore performs work on the piston 56.

[0082] Subsequently, the outlet valve 64 is opened. The piston moves again toward the inlet valve 62 and the outlet valve 64 and expels the exhaust gas out of the combustion chamber 10.

[0083] The exhaust gas flows via the connecting duct 26 into the reducing chamber 20. There the exhaust gas is treated/aftertreated with the reducing agent, and in particular by means of a catalyst 22, it is selectively catalytically reduced and thereby denitrified.

[0084] In the present exemplary embodiment, the reducing agent has a single constituent, specifically the gaseous hydrogen. Therefore the hydrogen is used both as a constituent of the fuel and also as a constituent of the reducing agent. Herein, the hydrogen is fed in from the store 28 into the reducing chamber 20.

[0085] Following its aftertreatment, the exhaust gas flows out of the reducing chamber 20 via the exhaust gas outlet duct 24. An outflow direction 54 of the exhaust gas is indicated in FIG. 2 with an arrow.

[0086] Subsequently, the inlet valve 62 is opened and the outlet valve 64 is closed. From here on, the process described above begins again.

[0087] By means of a periodic movement of the piston 56 in the process described, the crankshaft 60 is driven. With the aid of the connecting rod 58, an energy transfer from the piston 56 to the crankshaft 60 takes place.

[0088] Although the invention has been illustrated and described in detail based on the preferred exemplary embodiments, the invention is not restricted by the examples given and other variations can be derived therefrom without departing from the protective scope of the invention.