METHOD AND DEVICE FOR THERMAL MATERIAL TREATMENT IN A PULSATION REACTOR

Abstract

The invention relates to a device and a method for thermal treatment of a raw material in an oscillating hot gas flow of a pulsation reactor, comprising a burner, which is supplied with a mass flow, via at least one pipeline, for forming at least one flame, which produces the oscillating hot gas flow, wherein the flame is arranged in a combustion chamber, and wherein a reaction chamber follows the combustion chamber downstream of the combustion chamber. In order to be independent of the dimension of the device, it is proposed to provide the mass flow that is supplied to the flame with an externally impressed pulsation. The combustion chamber and/or the reaction chamber can then be varied in geometry to avoid resonances.

Claims

1. A device for thermal treatment of a raw material in a oscillating hot gas flow of a pulsation reactor, with a burner, which produces oscillating hot gas flow, whereby the flame is arranged in a combustion chamber, the burner is fed via at least one pipeline, wherein a reaction space adjoins the combustion chamber, wherein the a pulsation device that can be externally driven for at least one part of the mass flow, which is guided to the burner, is arranged downstream of the pipeline leading to the flame.

2. The device as claimed in claim 1, wherein the combustion chamber is provided with at least one element for changing its geometry.

3. The device as claimed in claim 1, wherein the reaction chamber is provided with at least one element for modifying its geometry.

4. The device as claimed in claim 1, wherein the pulsation device is a cylinder/piston unit.

5. The device as claimed in claim 1, wherein the pulsation device is a diaphragm, which is arranged in the pipeline leading to the burner and which forms a wall and which can be externally excited to oscillations.

6. The device as claimed in claim 1, wherein the pulsation device has a cylindrical housing, on the circumferential surface of which at least one opening is located with at least one sinusoidal edge, through which the mass flow flows towards the flames and which can be closed and opened with control.

7. The device as claimed in claim 1, wherein the pulsation device is provided with a bypass mass-flow opening.

8. The device as claimed in claim 1, wherein the mass flow comprises a fuel gas/air mixture, which is fed to the burner for the flame.

9. A method of thermal treatment of a raw material in an oscillating hot gas flow of a pulsation reactor, comprising a burner, to which a mass flow of fuel gas and air is supplied, via at least one pipeline, to form at least one flame, which generates the hot gas flow, whereby the flame is disposed in a burner, to which a reaction chamber is connected, wherein the mass flow to the burner is provided with an externally determined frequency and amplitude with pulsation.

10. The method as claimed in claim 9, wherein the geometry of the combustion chamber and/or of the reaction chamber can be adjusted to change a resonance frequency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Further advantages and features of the invention will become apparent from the following description of exemplary embodiments.

[0061] FIG. 1 shows a principle diagram of a device for thermal treatment of a raw material in an oscillating hot gas flow;

[0062] FIG. 2 shows a device for generating an oscillating mass flow in the external view; and

[0063] FIG. 3 shows a device according to FIG. 2 in a sectional view.

DETAILED DESCRIPTION

[0064] FIG. 1 shows a device for thermal treatment of a raw material in a oscillating stream of hot gas in the sectional view as a schematic representation.

[0065] A pulsating mass flow 2 is fed to burner 1. In the case of this mass flow, it relates to either combustion air, when burner 1 is a diffusion type burner or to a fuel/air mixture when burner 1 is a premixed burner, which is preferred. If the pulsating mass flow 2 is exclusively a combustion air for a diffusion burner, then fuel 3 is fed separately to burner 1.

[0066] In contrast to a premixed burner, a diffusion burner has the problem that the pulsating combustion air can partially lead to an oxygen deficiency, from which undesirable combustion values, e.g. soot, are generated in hot gas flow to be generated with the burner. Such combustion residues lead to a contamination of the material to be treated or synthesized. Therefore, instead of fuel 3, a further fuel/air mixture can be added here in the case of a premixed burner. The mass flow entering at the outlet of the burner in a flame generated there is then pulsed as a whole, whereby it is composed essentially of a uniformly flowing basic flow and a mass flow excited to pulsation.

[0067] The pulsating mass flow 2 originates from a pulsation device 4, which is integrated upstream of burner 1 into the pipeline 5, with which the pulsating mass flow 2 is fed to burner 1.

[0068] A continuous mass flow 6, which is converted into the pulsating mass flow 2 via the pulsation device 4, is fed to the pulsation device 4.

[0069] The pulsation device 4 can have a piston 7, which is reciprocated by means of a motor 8 so that the pulsation is thereby imposed on the continuous mass flow 6, which transforms it into the pulsating mass flow 2.

[0070] Instead of a piston 7, a membrane can also be moved, which forms a wall of the space 9 through which the mass flow flows. The pulsation of the mass flow 2 can also be produced in this way.

[0071] At the end of the burner 1, the pulsing fuel/air mixture 10 flows into a flame 11; this accordingly pulsates excitedly and thus generates a pulsating hot gas flow 12. The pulsating flame 11 thereby burns in a combustion chamber 13, which has a possibly double-walled, water-cooled wall 14.

[0072] Raw material 15 is added to the pulsating hot-gas flow 12, which leaves the combustion chamber 13, with which the raw material is passed through a reactor chamber 16, which is fluid-dynamically connected to the combustion chamber 13. The reactor space is, as required, provided with a double-walled, air-cooled or water-cooled wall 17.

[0073] The raw material 15 fed into the pulsating hot-gas flow 12 is correspondingly treated in the reactor chamber 16, whereby, depending on the composition of the raw material or raw material mixture, a material synthesis can take place here.

[0074] At the end of the reactor chamber 16, the finished product is discharged from the reactor chamber 16, whereby it is possible to add cooling air 19 to the hot gas flow, in order to quench the product 10 produced.

[0075] The product discharged from the reactor chamber 16 is then separated from the hot gas carrying it via a hot gas filter (not shown) or a cyclone.

[0076] It has been found that the dimensions of the device shown here are ultimately irrelevant for the finished product as long as the frequency and the amplitude of the pulsing hot gas flow 12 are fixed. This setting can be brought about via the pulsation device 4, which imposes its frequency and amplitude on the pulsating mass flow 2.

[0077] In order to prevent the occurrence of undesired resonances in the combustion chamber 13 and in the reactor chamber 16 downstream the latter, which would lead to an undesirable increase in the amplitudes produced in the present case, the device is provided with a modification element 20 for the geometry of the combustion chamber or the reaction chamber. In the illustrated example, this change element is formed by a displaceable bottom 20 of the combustion chamber 13. With this change element 20, the resonance frequency of the device shown here can be modified in such a way that it can no longer lead to an undesirable resonance-induced amplification of the amplitudes, which are generated by the pulsating flame 11.

[0078] It should be pointed out at this point that the combustion chamber as illustrated here and the resonance chamber connected to it are in principle constructed like a Helmholtz resonator, i.e., not like half-wave or quarter-wave resonators similar to organ pipes, as described above. Thus, with conventional dimensions of such a device that can be used as a laboratory reactor, depending on the position of the modification element and the volume resulting there from, e.g., the combustion chamber as a Helmholtz resonator and the set temperature of the hot-gas mass flow, it can have a resonance frequency of about 40 to 160 Hz, which is to be avoided as operating frequency.

[0079] FIGS. 2 and 3 show a suitable pulsation device in more detail: via a motor shaft 21, a multi-vane rotary gale valve 22 can be rotated, which opens and closes an opening 23 with a sinusoidal surface. Through this opening 23, the mass flow 6 flowing continuously into the pulsation device is converted into a pulsating mass flow 2, whereby the pulsation has a substantially sinusoidal course, because the opening 23 has a sinusoidal surface through which the mass flow takes place. The set frequency of the mass flow can then be determined or regulated by the rotational speed generated by the drive shaft 21 on the rotary gale valve 22 and by the number of vanes, which the rotary gale valve 22 has. A frequency between 1 Hz and 500 Hz is customary here.

[0080] It is also possible to supplement the opening 23 with a section of rectangular form 24. By means of a second gale valve 25, which can close this rectangular section as required, a uniform basic flow can now be implemented for the mass flow, which causes a bypass flow with respect to the pulsating mass flow.

[0081] The second gale valve 25 can be adjusted accordingly via a positioning pin 26.

REFERENCE LIST

[0082] 1 burner [0083] 2 pulsating mass flow [0084] 3 fuel [0085] 4 pulsation device [0086] 5 pipeline [0087] 6 continuous mass flow [0088] 7 pistons [0089] 8 motor [0090] 9 chamber exposed to the mass flow [0091] 10 pulsating fuel/air mixture [0092] 11 flame [0093] 12 pulsating hot gas flow [0094] 13 combustion chamber [0095] 14 walls [0096] 15 raw material [0097] 16 reactor space [0098] 17 walls [0099] 18 product [0100] 19 cooling air [0101] 20 change element [0102] 21 drive shaft [0103] 22 rotary gale valve [0104] 23 opening [0105] 24 rectangular section [0106] 25 second gale valve [0107] 26 positioning pin

LITERATURE

[0108] /1/ A. A. Putnam and W. R. Dennis: “Organ Pipe Oscillations in Flame-filled tubes”; Proc. Comb. Inst. 4, S. 556 ff., 1952 [0109] /2/ H. Büchner: “Experimental and theoretical studies of the mechanisms of self-excited pressure oscillations in technical premixed combustion systems”; Dissertation, University of Karlsruhe, Shaker-Verlag Aachen, 1992 [0110] /3/ DD 114 454 B1 [0111] /4/ DD 155 161 B1 [0112] /5/ DD 245 648 A1 [0113] /6/ DE 10 2006 046 803 A1 [0114] /7/ DE 101 09 892 B4 [0115] /8/ DE 10 2006 046 880 B4 [0116] /9/ DE 10 2006 032 452 B4 [0117] /10/ Chr. Bender: “Measurement and calculation of the resonance behaviour of coupled Helmholtz resonators in technical combustion systems”, Dissertation, University of Karlsruhe KIT, 2010