METHOD FOR THE POST-COMBUSTION OF FLUE GASES

Abstract

A method for the post-combustion of flue gases, a silane or silicon and hydrogen or a hydrogen-releasing compound being fed to the flue gas for post-combustion, as well as a device being adapted for implementing the method for the post-combustion of flue gases. Also, the use of the silicon carbide and/or silicon nitride produced by the method, in the construction industry, as well as steam for generating power via a turbine.

Claims

1. A method for the post-combustion of flue gases, wherein a silane, and/or silicon and hydrogen or a hydrogen-releasing compound are fed to the flue gas for post-combustion.

2. The method as recited in claim 1, wherein the silane is selected from the group that includes pentasilane, hexasilane, heptasilane, octasilane, nonasilane, decasilane, undecasilane, dodecasilane, tridecasilane, tetradecasilane and/or pentadecasilane.

3. The method as recited in claim 1, wherein the hydrogen-releasing compound is ammonia.

4. The method as recited in claim 1, wherein the silicon is present in powdered or amorphous form.

5. The method as recited in claim 1, wherein the silane or the silicon and hydrogen or the hydrogen-releasing compound is fed to a post-combustion device of a combustion system for fossil fuels.

6. The method as recited in claim 1, wherein silicon carbide and silicon nitride are formed by post-combusting the nitrogen, nitrogen oxide and carbon dioxide contained in the flue gas with the silane or silicon and hydrogen or the hydrogen-releasing compound.

7. A use of the post-combustion products, silicon carbide and/or silicon nitride, produced using the method according to claim 6 in the construction industry, in particular in concrete construction.

8. The use of steam produced by the method according to any of claim 1 for generating power via a turbine.

9. A device for implementing the method for the post-combustion of flue gases according to any of the claim 1, the device having a post-combustion device (8) that is adapted for combusting flue gas.

10. The device as recited in claim 9, wherein the device has a chamber (9) that is adapted for containing silanes, and/or one or a plurality of chambers adapted for containing silicon and hydrogen, or a hydrogen-releasing compound.

Description

[0022] An exemplary embodiment of the present invention will be described in greater detail below with reference to the drawings. In the drawing,

[0023] FIG. 1 schematically shows a combustion system for carrying out a post-combustion in accordance with a specific embodiment of the present invention.

[0024] FIG. 2 is an enlarged representation of the waste gas combustion chamber shown in FIG. 1 to illustrate the chemical post-combustion processes.

[0025] FIG. 3 schematically shows a combustion system for carrying out a post-combustion in accordance with another specific embodiment of the present invention.

[0026] FIG. 1 shows a combustion system for fossil fuels in which natural gas or coal are combusted in a combustion chamber 1. In a tank or water reservoir 2 located thereabove, steam 3 is produced by the combustion and drives turbine 5 by a feeding, preferably regulated by a valve 4. Turbine 5, as well as a generator are used for generating electrical power. The flue gases are conducted into a waste gas combustion chamber 8 via a waste gas pipe 6, in particular following a scrubbing of the flue gas in a suitable device 7. There, with the aid of silane, or silicon and hydrogen, or a hydrogen-releasing compound, for example, a liquid silane from a silane tank 9, the carbon dioxide of the flue gas is combusted to form silicon carbide and steam. The nitrogen and the traces of nitrogen oxides of the flue gas are combusted here to form silicon nitride and steam. The energy produced there should likewise be used to boost steam production. Residual gas may be removed from waste gas combustion chamber 8 through a residual gas exhaust 10, while SiC and Si.sub.3N.sub.4 collect in this way as a powdered mixture at the bottom, facilitating removal thereof from the waste gas combustion chamber via a removal region 11.

[0027] To illustrate the post-combustion processes, FIG. 2 diagrammatically shows an enlarged representation of waste gas combustion chamber 8 from FIG. 1 whereby the hydrogen (H) of the silane chain attacks the oxygen atoms (O) of the carbon dioxide (CO.sub.2) and combusts them to produce water (H.sub.2O). The nitrogen (N) reacts with the silicon (Si) to produce silicon nitride (Si.sub.3N.sub.4). At this point, the carbon (C) combines with the silicon (Si) to form silicon carbide (SiC).

[0028] FIG. 3 shows another specific embodiment of a combustion system for carrying out a post-combustion. In this specific embodiment of a combustion system, combustion chamber 1 for fossil fuels, in which natural gas or coal are combusted, and waste gas combustion chamber 8, in which the flue gases produced there are combusted further, are immediately proximate to one another. Above combustion chamber 1, in which the natural gas or coal are combusted, the system features a tank or water reservoir 2, in which steam 3 is produced that drives a turbine 5 preferably via a feeding regulated by a valve 4. In this specific embodiment of a combustion system, the flue gases from the combustion of the fossil fuels are conducted via feed 12 into waste gas combustion chamber 8, where carbon dioxide, nitrogen, and nitrogen oxides of the flue gas are combusted with the aid of silane, which is fed from silane tank 9 to form silicon carbide and silicon nitride. The residual gas may be removed from waste gas combustion chamber 8 through a residual gas exhaust 10, while SiC and Si.sub.3N.sub.4 may be removed via a removal region 11.

[0029] Such a specific embodiment of a combustion system, where combustion chamber 1 for fossil fuels and waste gas combustion chamber 8 are immediately proximate to one another, may be implemented in a new construction of combustion systems. The dense configuration of the combustion chambers facilitates the feeding of the flue gases. In particular, the utilization of the combustion heat from the silane combustion to produce steam is also simplified; respectively, a utilization of this energy in a tank 2, in which water is co-heated by the combustion of fossil fuels and silane, is made possible.

LIST OF REFERENCE NUMERALS

[0030] 1 combustion chamber [0031] 2 water reservoir [0032] 3 steam [0033] 4 valve [0034] 5 turbine [0035] 6 waste gas pipe [0036] 7 device for scrubbing flue gas [0037] 8 waste gas combustion chamber [0038] 9 silane tank [0039] 10 residual gas exhaust [0040] 11 removal region for SiC and Si.sub.3N.sub.4 [0041] 12 feed for waste gas