EP1081434B2 - Device for generating a rotating gas flow - Google Patents

Description

The invention relates to a combustion plant according to the features of the preamble of claim 1.

The flow channels are used to regulate by means of the injected media, the composition of the transported away through the flow channel of the incinerator flue gas mixture and its temperature and its residence time. However, the composition, temperature and residence time should not only be regulated but, above all, evened out. In this way, optimal afterburning of the flue gas mixture can be ensured and the desired, low emission values can be maintained. For this purpose, a thorough mixing of the flue gas mixture is necessary. Through the generation of rotating flows in the flow channel by means of devices with corresponding nozzle arrangements one tries to achieve this complete mixing.

A generic combustion system is for example off US-A-5,252,298 known. The arranged in a plane nozzles are aligned tangentially to an imaginary in the middle of the flow channel circle, so that in the flow channel, a rotating flow is generated. At one off DE-A-19 648 639 known combustion system, the flow rate is controlled by means disposed in the flow channel opposite each other nozzles such that at least two oppositely rotating flows in the flow channel arise. The problem with these known rotating flows is that an almost vortex-free eye is formed in the middle of the flow, so that complete mixing and thus no uniform composition, temperature distribution and residence time are obtained.

The object of the present invention is therefore to provide an economical incineration plant with which complete mixing of flue gas mixtures in the flow channel of the incineration plant is obtained. This object is fulfilled by a combustion plant according to the features of claim 1.

Due to the special arrangement of first nozzles according to claim 1 in a plane of injection in at least one first wall portion per wall, which is at least a first wall portion of the opposite wall obliquely opposite, and by the alignment of the first nozzle in the injection plane, that in the injection plane lying angle between the wall and a sprayed jet is at least approximately 90 °, on the one hand generates a rotating flow in the flow channel and on the other hand achieved a very good mixing of the flue gas mixture. By "obliquely opposite", it is meant that the first wall sections for swirling the flowing material in the projection do not overlap or only partly laterally overlap approximately in the direction of the jet flowing through the first nozzles, in particular if the first nozzles are distributed on first wall sections having a length 1 of 50% and more ensures that jets of doused media reach the center of the flow channel, in that the sum L of lengths of the first wall sections of a wall is at least approximately 40% to 80% of the total wall width b, ie the first nozzles extend only over a portion of the width b of the wall, material and assembly costs are saved for the nozzles, the mixing efficiency is maintained.

In a specific embodiment, in addition to the first nozzles in a second wall section at an angle β opposite the first nozzles and obliquely directed against the center of the flow channel, second nozzles are provided in the injection plane, which further improves the mixing.

Preferably, a plurality of first and more preferably also a plurality of second wall sections are provided with first and second nozzles per wall, so that vortex areas are generated with counter-rotating vortices, which further improves the mixing.

It is particularly advantageous to align the second nozzles at an angle α with respect to the injection plane with an injection component in the downstream direction. In this case, each of the second nozzles with a Eindüskomponente have a different angle α with respect to the injection plane or all other nozzles nozzle with a Eindüskomponente in the same by the angle α tilted with respect to the injection level in the flow channel. In this way, the jets of these nozzles are adjustable so that they flow helically in one another.

In a further preferred embodiment, first nozzles are arranged in a first wall section on all four walls delimiting the flow channel. In this case, the first wall sections are in the circumferential direction opposite to the rotating flow respectively at the beginning of a wall, so that they are spaced from the first wall portion of the adjacent wall and do not touch each other. By this distribution of the first wall sections and their length of more than 0.5b, a very good rotating flow can be generated and achieve optimum mixing of the flue gas mixture by injecting from all four sides to the center of the flow channel.

It is particularly advantageous to arrange the nozzles of all four walls in one injection plane. However, the nozzles can also be arranged in two parallel injection planes spaced apart from one another in the flow direction, with nozzles located opposite one another being arranged in one plane.

Ideally, point-symmetrically opposite wall sections are the same length.

Advantageously, fresh secondary air and / or recirculated flue gas are injected. When fresh secondary air and recirculated flue gas are injected, preferably annular gap nozzles are provided. The core jet of the annular gap nozzles consists of recirculated flue gas and the ring jet of fresh secondary air.

Particularly advantageous is a control system, with the aid of which the flow rate of the media to be atomized is independently controllable, at least for arranged on opposite walls nozzles.

If at least one injection level is arranged in the area of a flame blanket of the incineration plant situated in the transitional region between a combustion chamber and the flue gas outlet, cooling of the flame blanket exposed to a very high thermal load is achieved by injecting the media to be atomized in addition to the mixing and regulation of the flue gas mixture.

Further advantageous embodiments are the subject of further dependent claims.

Fig. 1a, b

eine erste Ausführungsform der Erfindung mit an zwei einander gegenüberliegenden Wänden eines rechteckigen Strömungskanals angeordneten ersten Düsen und zweiten Düsen, wobei Fig. 1a den Schnitt längs des Strömungskanals und Fig. 1b einen Schnitt quer zum Strömungskanal zeigt;

Fig. 2a, b, c

eine zweite Ausführungsform der Erfindung mit einer Anordnung der Düsen analog derjenigen aus den Fig. 1a und 1b, wobei jedoch an den anderen zwei Wänden des rechteckigen Strömungskanals ebenfalls Düsen angeordnet sind und zwar in einer zweiten, zur ersten Eindüsebene in Strömungsrichtung beabstandeten, parallelen Eindüsebene und die Darstellung in Fig. 2a analog zu der aus Fig. 1a und die Darstellungen in den Fig. 2b und 2c analog derjenigen aus 1b sind.;

Fig. 3a, b

eine dritte Ausführungsform der Erfindung mit ersten Düsen an allen vier Wänden des rechteckigen Strömungskanals in einer Eindüsebene mit Darstellung analog den Fig. 1a und 1b;

Fig. 4a, b,

eine vierte Ausführungsform der Erfindung mit ersten Düsen an allen vier Wänden des rechteckigen Strömungskanals, wobei die Düsen in zwei voneinander in Strömungsrichtung beabstandete, parallelen Eindüsebenen verteilt sind und zwar jeweils einander gegenüberliegende erste Düsen in einer Eindüsebene und mit Darstellung analog den Fig. 1a und 1b;

Fig. 5

ein Beispiel für eine Ringspaltdüse;

Fig. 6

ein Steuerungssystem für die getrennte Steuerung der Durchsatzmenge für an verschiedenen Wänden angeordnete Düsen;

Fig. 7

eine weitere Ausführungsform der Erfindung zur Erzeugung von wenigstens zwei gegenläufig rotierenden Wirbeln.

The invention is explained in more detail below with reference to a few selected examples. The Fig. 1 to 6 show purely schematically:

Fig. 1a, b

a first embodiment of the invention with arranged on two opposite walls of a rectangular flow channel first nozzles and second nozzles, wherein Fig. 1a the section along the flow channel and Fig. 1b shows a section across the flow channel;

Fig. 2a, b, c

a second embodiment of the invention with an arrangement of the nozzles analogous to those of the Fig. 1a and 1b However, although nozzles are arranged on the other two walls of the rectangular flow channel and in a second, parallel to the first injection plane in the flow direction, parallel injection plane and the illustration in FIG Fig. 2a analogous to the Fig. 1a and the representations in the Fig. 2b and 2c analogous to those of 1b .;

Fig. 3a, b

a third embodiment of the invention with first nozzles on all four walls of the rectangular flow channel in a Eindropfenbene represented analogously to the Fig. 1a and 1b ;

Fig. 4a, b,

a fourth embodiment of the invention with first nozzles on all four walls of the rectangular flow channel, wherein the nozzles are distributed in two mutually spaced in the flow direction, parallel injection planes, namely each opposing first nozzles in a Eindropfenbene and with representation analogous to Fig. 1a and 1b ;

Fig. 5

an example of an annular gap nozzle;

Fig. 6

a control system for separately controlling the flow rate for nozzles arranged on different walls;

Fig. 7

a further embodiment of the invention for generating at least two counter-rotating vertebrae.

In the Fig. 1a to 4a are each of a waste incineration plant a section of a flue gas outlet 10 and a combustion chamber 12 and a transition region 20 between the combustion chamber 12 and flue 10 with a flame blanket 14 in section along the flue gas outlet 10 shown. For the withdrawal of flue gas mixtures formed during combustion, a rectangular flow channel 18 is provided, which comprises the transition region 20 from the combustion chamber 12 to the flue gas outlet 10 and the flue gas outlet 10. The principal flow direction of the flue gas mixture is indicated by an arrow 16. In the Fig. 1b to 4b In each case, sections are shown transversely to the flow channel 18 in the region of an injection plane 22, in which nozzles 24 are arranged for injecting atomizable media. The nozzles 24 and their orientation are represented by arrows in all representations. The refuse flow direction is indicated by an arrow 9.

All in the Fig. 1a to 4b shown embodiments have at least two opposing walls 26 first wall portions 28 having a length l ₁ of at least approximately 40% to 80% of the wall width b of a wall 26. The first wall sections 28 are in each case point-symmetrical with respect to the central longitudinal axis 32 of the flow channel 18 as a geometric axis of symmetry and are bounded on one side by the adjacent wall 26. In the first, each point-symmetrically opposite wall portions 28 first nozzles 24a are arranged in a row 22 in a row. The first nozzles 24a are aligned in the injection plane 22, so that they inject into this, wherein the lying in the injection plane angle γ between injected jet 30 and wall 26 is about 90 °. This arrangement of nozzles 24 allows a good mixing of the flow channel 18 for rotation excited and flowing in the direction 16 flue gas mixture.

The injection level 22 is in all examples in the area of the flame ceiling 14, which is arranged in the transition region 20 between flue gas outlet 10 and combustion chamber 12. The flame blanket 14 is either penetrated even by nozzles 24, as shown in all four examples, and / or it is via nozzles 24a ', 24b''which are arranged in walls (26) laterally below the flame blanket (14), with undermined media ", as in the Fig. 2 to 4 is shown. In this way, the flame blanket 14 can be cooled by the injected media.

In the Fig. 1a and 1b an embodiment is shown in which on two opposite walls 26 first wall portions 28 are provided with a length l ₁ of about 40% to 50% of the wall width b. In a second wall section 34 with length l ₂ , the row of the first nozzles 24a in the first wall section 28 are complementary, second nozzles 24b, which are aligned at an angle β with respect to the first nozzle 24a obliquely against the center of the flow channel 18 represented by the central longitudinal axis 32 are. The angle β is in this example about 25 °, but it can be between 20 ° and 50 °. The lengths l ₁ and l _{2 of} the two wall sections 28, 34 complement each other in this example to the entire wall width b, but this need not necessarily be so. Opposite the injection plane 22, the second nozzles 24b are aligned in a common plane 36, which is tilted by the angle α with respect to the injection plane 22. The angle α in this example is about 10 °, but may vary and be between 5 ° and 15 °. The second nozzles 24b are aligned such that the beams 30 generated by them flow into one another helically. Instead of a common plane 36, the second nozzles 24b may also be tilted at individual angles α with respect to the injection plane 22.

In the Fig. 2a to 2c an embodiment is shown in which on all four walls 26 of the flow channel 18 first nozzles 24a in a first wall portion 28 and second nozzles 24b in a second wall portion 34 analogous to that in the Fig. 1a and 1b illustrated embodiment are arranged. The first wall sections 28 are arranged in the circumferential direction against the rotating flow in each case at the beginning of a wall 26. The nozzles 24a, 24b and 24a ', 24a'',24b', 24b '' are arranged in two parallel, in the flow direction spaced injection levels 22 and 22 *, wherein nozzles 24 on opposite walls 26 in a common injection plane 22nd , 22 * are arranged. The distance d between the injection planes 22, 22 * can be between 0.4m and 3m.

In the in Fig. 3a, 3b As shown, first wall sections 28 with first nozzles 24a are arranged in a single injection plane 22 on all four walls 26 of the flow channel 18. The length l _{1 of} the first wall sections 28 is well above 0.5b, preferably at 0.55b to 0.75b. The remainder of each wall 26 remaining on the entire wall width b is free of nozzles 24. By this arrangement and orientation of the first nozzles 24a, it is possible to jet jets 30 into the center of the generated rotating flow so that complete mixing of the flue gas mixture takes place ,

Depending on the design of the flow channel 18 and the configuration of the walls 26, it may be necessary, be it for optimizing the flow or because the four walls 26 can not be equipped in a single plane with nozzles 24a, the nozzles 24a instead of in a single Injection level 22 (cf. Fig. 3a, 3b ) in two mutually parallel injection planes 22 and 22 * to arrange, as shown in the Fig. 4a, 4b is shown.

All nozzles are designed so that media to be injected can be injected at a pressure of 500 Pa to 5000 Pa.

In Fig. 5 is an annular gap nozzle 24 * shown, as provided for example for injecting fresh secondary air and recirculated flue gas. Shown is a first supply line 40 for the supply of a first medium, in this case recirculated flue gas, in a core nozzle 42 and a core jet producing nozzle part and a second supply line 44 for the supply of a second medium, in this case fresh secondary air, in a formed as an annular gap 46 and a ring beam producing nozzle part.

Via a control system 48, as it is in Fig. 6 is shown for annular gap nozzles 24 *, the different conditions, as they can prevail on different sides of the flow channel 18, better taken into account. The flow rates of the media to be injected are controllable independently of each other via the control system 48 and the valves 54 in the example shown for the upstream with respect to the refuse flow 9 half 52 and the downstream half 50 of the flow channel 18. It would also be conceivable to have separate control of the flow rates for the nozzles 24 on all four walls 26.

To regulate the temperature, the O ₂ content and to obtain the highest possible minimum residence time of the flowing through the flow channel flue gas mixture preferably nozzles 24 are provided for secondary air and nozzles 24 for recirculated flue gas. These nozzles 24 can be arranged either mixed in a row next to each other or in two rows one above the other, so that there is a separate injection level 22 for each nozzle 24. If annular gap nozzles 24 * are provided, the core jet consists of flue gas and the ring jet of secondary air, as for Fig. 5 described.

The embodiments shown here are not exhaustive of the invention. That's the way it is Example possible to use the device in incinerators and waste incineration plants, in which the transition region 20 between the combustion chamber 12 and flue gas outlet 10 is characterized by a constriction. Also, further injection levels 22 may be provided deeper in the combustion chamber 12 or higher in the flue 10. Instead or in addition to flue gas and secondary air, other media such as steam activated carbon, stove coke (HOK), waste z. B. in the context of a residue recycling, fuels etc. are injected. Also, to obtain a reducing atmosphere, the device can be used. In the same direction of rotation as the first nozzles 24a, burners 2m to 3m above the injection plane 22 may be arranged on two opposite walls 26.

FIG. 7 shows a further embodiment of the invention, in which two counter-rotating vortices 60 ', 61' are generated. The device goes by reflection on the bottom wall 26 of the in Fig. 2b shown, ie the first and second nozzles shown there are doubled. The walls 26 of the device each have two first wall sections 28a1 and 28a2 or 28b1 and 28b2 with first nozzles 24a. The first nozzles 24a of the first wall sections 28a2, 28b2 in the lower half of the cross-section are arranged obliquely opposite each other and produce a clockwise-rotating first vortex 61 '. This is amplified by the second nozzles 24b of the second wall portions 34a2, 34b2. The second nozzles 24b radiate in a direction offset by +/- β with respect to the jet direction of the first nozzles. These second wall portions 34a2, 34b2 are also opposite each other obliquely. The wall portions in the lower half of the illustrated cross section define a first vortex region 61. A second vortex region 60 is defined by the first and second wall portions 28a1, 28b1, 34a1, 34b1 in the upper part of FIG FIG. 7 Are defined. The local second vortex 60 'rotates counterclockwise. The first wall sections 28a1, 28a2, 28b1, 28b2 each have a length l ₁ . Per wall 26 results in a total length L = l1 + l1 of about 0.5b. The obliquely opposite first wall sections 28a1 and 28b1 (second swirl 60 ') and 28a2 and 28b2 (second swirl 61') define the direction of rotation of the swirl 60 ', 61'. The second nozzles 24b then radiate to enhance the rotation, ie tangentially in the direction of rotation, to an imaginary circle about the center of the vortex 60 'and 61', respectively.

Claims (16)

1. An incineration plant, with a rectangular flow duct (18) which comprises a flue-gas outlet (10) of the incineration plant, in particular of a garbage incineration plant, with a plurality of nozzles (24) for injectable media, said nozzles being arranged in one injection plane (22), which is lying in the region of the flame cover (14), on two walls (26) of wall width b which lie opposite one another and delimit the flow duct (18), wherein the flow duct (18) comprises a transitional region (20) from a combustion chamber (12) of the incineration plant to the flue-gas outlet (10), and wherein in each case, in at least one first wall portion (28, 28a1, 28a2, 28b1, 28b2) of the two walls (26) lying opposite one another, first nozzles (24a) are aligned in a row in such a way that they inject into the injection plane (22) and the angle γ, lying in the injection plane (22), between the wall (26) and an injected jet (30) amounts to at least approximately 90°, the sum L of the lengths 1 of the first wall portions (28, 28a1, 28a2, 28b1, 28b2) amounting to at least approximately 0.4b < L < 0.8b, and the at least one first wall portion (28, 28a1, 28a2) of one wall lying obliquely opposite the at least one first wall portion (28, 28b1, 28b2) of the opposite wall, the wall portions not or only partially overlapping one another laterally in the projection approximately in the direction of the jet flowing into the first nozzles.
2. The incineration plant as claimed in claim 1, wherein the opposite walls have in each case a first wall portion (28), said wall portions lying point-symmetrically opposite one another, with the longitudinal center axis (32) of the flow duct (18) as the axis of symmetry, and being delimited on one side by the adjacent wall (26).
3. The incineration plant as claimed in claim 1 or 2, wherein second nozzles (24b) are arranged in each case in the injection plane (22) in at least one second wall portion (34, 34a1, 34a2, 34b1, 34b2) of the two opposite walls (26), |β|> 0°, preferably 20°<|β|< 50°, applying to the angle β, lying in the injection plane, between the jets injected by the first and the second nozzles (24, 24b), and preferably the at least one second wall portion (34, 34a1, 34a2, 34b1, 34b2) of one wall lying obliquely opposite the at least one second wall portion (34, 34a1, 34a2, 34b1, 34b2) of the opposite wall.
4. The incineration plant as claimed in claim 3, wherein, for generating a rotating vortex, each of the two opposite walls has a first (28) and a second (34) wall portion, and the first and the second wall portions lie in each case point-symmetrically opposite one another, with the longitudinal center axis (32) in the flow duct (18) as the axis of symmetry, and are delimited on one side by the adjacent wall (26').
5. The incineration plant as claimed in one of claims 1 to 3, wherein, for generating at least two contra-rotating vortices, each of the two opposite walls have at least two first wall portions (28, 28a1, 28a2, 28b1, 28b2).
6. The incineration plant as claimed in claim 5, wherein each of the two opposite walls have additionally two second wall portions, in each case a first (28al, 28a2) and a second (34a1, 34a2) wall portion of one wall forming, with the directly opposite second (34b1, 34b2) or first (28bl, 28b2) wall portions of the opposite wall, a vortex region (60, 61), and the jets injected by the second nozzles (24b) being inclined at + |β| in a first vortex region (61) and at -|β| in a second vortex region (60) in relation to the jets injected by the first nozzles (24a).
7. The incineration plant as claimed in one of claims 3 to 6, wherein the second nozzles (24b) of the second wall portion (34) are aligned with an injection component at an angle α, which lies preferably between 5° and 15°, with respect to the injection plane (22) and preferably into a common plane (36) in the direction of flow in the flow duct (18).
8. The incineration plant as claimed in one of the preceding claims, wherein all four walls (26) of the flow duct (18) have a first wall portion (28) with first nozzles (24a), the first wall portions (28) being arranged in a circumferential direction, counter to the rotating flow, in each case at the start of a wall (26) and so as to be spaced apart from the first wall portion (28) of the adjacent wall (26).
9. The incineration plant as claimed in claim 8, wherein the nozzles (24) of all four walls (26) lie in the same injection plane (22).
10. The incineration plant as claimed in claim 8, wherein the nozzles (24) are arranged in two parallel injection planes (22, 22*) spaced apart from one another in the direction of flow, nozzles lying opposite one another lying in the same injection plane (22, 22*).
11. The incineration plant as claimed in either one of claims 5 and 6, wherein wall portions (28, 34) lying obliquely or point-symmetrically opposite one another have approximately the same length 1.
12. The incineration plant as claimed in one of the preceding claims, wherein the feed pressure at which the injectable media enter the nozzles is between 500Pa and 5000Pa, and wherein the throughput quantities for nozzles (24) arranged on different walls (26) can be controlled preferably independently of one another by means of a control system (48).
13. The incineration plant as claimed in one of the preceding claims, wherein the nozzles (24) provided are annular-gap nozzles (24*).
14. The incineration plant as claimed in one of the preceding claims, wherein nozzles (24) for the injection of secondary air and of recirculated flue gas are provided.
15. The incineration plant as claimed in claim 13, wherein the core jet of the annular-gap nozzles consists of recirculated flue gas and the annular jet consists of secondary air.
16. The incineration plant as claimed in one of the preceding claims, wherein at least one injection plane (22) lies in the region of a flame cover (14) arranged in the transitional region (20), so that nozzles (24, 38) pass through the flame cover (14) and/or the nozzles (24, 38) are arranged in walls (26) laterally below the flame cover (14), in such a way that they cool the flame cover (14) by injection.

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