EP0569300B1 - Combustion chamber with adjustable passages for primary air - Google Patents

Description

Known combustion chambers, in particular those with which gas turbines are fitted, include numerous oxidant intake orifices allowing combustion of the injected fuel. Thus we distinguish the intake ports of the primary oxidant, which plays an essential role in the course of combustion proper, from the intake ports of the dilution oxidant, which, as its designation suggests, has the function main, by mixing with the burnt gases resulting from the combustion, diluting them and thus homogenizing the temperature and regulating the flow rate to allow a satisfactory supply of the blades of the gas turbine.

The primary oxidizer intake devices must allow very different operating speeds to be obtained. Thus, at idle speed, the residence time of the combustion gases in the intake area of the oxidant admitted around the fuel injectors and through the primary oxidant intake orifices must be long, in order, on the one hand , to promote combustion stability, on the other hand, to reduce polluting emissions of carbon monoxide (CO) and unburnt hydrocarbons (CHx). On the full gas regime, the residence time of the combustion gases in said zone must, on the contrary, be short, in order to reduce the polluting emissions of nitrogen oxides (NOx).

Furthermore, the same chamber must satisfy these contradictory requirements. In addition, the values of the primary oxidizer flow rates may themselves vary.

In order to solve all the problems relating to the admission of primary oxidant, the invention proposes a main arrangement according to which the locations of the intake ports of primary oxidant are adjustable parallel to the axis of the combustion chamber, allowing the adjustment of the residence time of the combustion gases inside the combustion zone, supplemented or not advantageously by secondary provisions allowing the adjustment of the flow rate of the primary oxidant.

The invention therefore relates to a combustion chamber comprising a geometric axis, and, an external wall and an internal wall, which define an enclosure inside which combustion of a fuel takes place and of which at least l 'one of these walls is in particular provided for this purpose with passages regulating the admission inside the enclosure of a primary oxidizer.

The combustion chamber further comprises at least one fuel injector associated with a combustion oxidizer intake device.

These characteristics are known in particular from EP-A-100 135 which relates to a return combustion chamber in which the axial movement of a ring provided with orifices regulates the passage of air from the inlet orifices. Furthermore, DE-A-1 945 921 describes a combustion chamber in which a rotating mobile ferrule adjusts the sections of the secondary air inlets, oblong orifices being provided.

According to the invention, the passages of adjustable sections include first oblong orifices with axes substantially contained in radial planes passing through the geometric axis of the combustion chamber and formed in said wall; shutter means crossed by second orifices centered substantially in the same radial planes as the first orifices; and a device for adjusting the positions of said shutter means parallel to said geometric axis, capable of producing an adjustment overlap of each first orifice by a second orifice; in addition, the combustion oxidizer intake device is provided with a diaphragm for adjusting the combustion oxidant passages, and with a device for adjusting said diaphragm, while the controls for the device for adjusting the positions of said means of the shutter and the diaphragm adjustment device are synchronized, so as to obtain particular configurations.

• selon une première réalisation, chaque premier orifice comporte deux lisières parallèles écartées d'une distance déterminée, cependant que chaque deuxième orifice a une périphérie circulaire de diamètre sensiblement égal à ladite distance déterminée, ledit réglage des positions des moyens d'obturation réalisant au moins un recouvrement de position réglable de chaque premier orifice par un deuxième orifice ;
• selon une deuxième réalisation, chaque deuxième orifice a une section oblongue sensiblement égale à, et de même forme que celle d'un premier orifice, d'axe sensiblement contenu dans le plan radial passant par ledit axe géométrique et par l'axe d'un premier orifice, cependant que ledit recouvrement présente deux valeurs particulières : une valeur maximale, qui correspond à la superposition des premiers et des deuxièmes orifices, et, une valeur minimale, qui correspond à la superposition de seulement une partie de chacun des premiers orifices par un deuxième orifice ;
• les configurations particulières comportent une première configuration, dans laquelle lesdits recouvrements des orifices ont leur valeur maximale et les sections desdits passages du diaphragme ont leur valeur minimale et, soit une deuxième configuration dans laquelle lesdits recouvrements des orifices ont leur valeur minimale, et les sections de passages du diaphragme ont leur valeur maximale, soit, en variante, une deuxième configuration dans laquelle lesdits recouvrements des orifices ont une valeur maximale, et, les sections de passages du diaphragme ont leur valeur maximale;
• les valeurs de perte de charge du débit de comburant traversant l'ensemble desdits passages d'admission de comburant primaire et des passages du diaphragme dans lesdites première et deuxième configurations sont égales ;
• lesdits moyens d'obturation sont constitués par des plaques montées coulissantes sur au moins l'une des faces de ladite paroi, selon une direction parallèle à l'axe géométrique ;
• lesdites plaques sont montées coulissantes sur la face de ladite paroi opposée à celle délimitant l'enceinte de combustion ;
• la chambre de combustion comporte une couronne annulaire, d'axe confondu avec ledit axe géométrique, montée pivotante par rapport à ladite paroi autour de cet axe géométrique, cependant que l'un des deux ensembles de pièces constitués par la couronne annulaire et par les plaques, est muni d'une pluralité de rampes inclinées par rapport audit axe géométrique et que l'autre ensemble de pièces est muni d'ergots, dont chacun est maintenu en appui sur l'une des rampes, un ergot par rampe ;
• chaque rampe est constituée par une rainure ménagée dans l'ensemble de pièces comportant lesdites rampes ;
• chacune des parois externe et interne est traversée par une pluralité desdits passages d'admission de comburant primaire, cependant que deux couronnes annulaires, l'une externe, l'autre interne, sont associées auxdites parois externe et interne, respectivement, et qu'un levier unique est monté pivotant sur un fond transversal reliant lesdites parois externe et interne, autour d'un axe de pivotement parallèle à l'axe géométrique, et est attelé auxdites couronnes annulaires par l'intermédiaire de pattes qui en sont solidaires, de manière à réaliser la synchronisation des commandes de pivotement des deuxdites couronnes annulaires.

The following advantageous arrangements are also preferably adopted:

• according to a first embodiment, each first orifice has two parallel selvedges spaced by a determined distance, while each second orifice has a circular periphery of diameter substantially equal to said determined distance, said adjustment of the positions of the shutter means achieving at least one adjustable position overlap of each first port by a second port;
• according to a second embodiment, each second orifice has an oblong section substantially equal to, and of the same shape as that of a first orifice, with an axis substantially contained in the radial plane passing through said geometric axis and through the axis of a first orifice, however that said overlap has two particular values: a maximum value, which corresponds to the superposition of the first and second orifices, and, a minimum value, which corresponds to the superposition of only part of each of the first orifices by a second port;
• the particular configurations comprise a first configuration, in which said coverings of the orifices have their maximum value and the sections of said passages of the diaphragm have their minimum value and, that is to say a second configuration in which said coverings of the orifices have their minimum value, and the sections of diaphragm passages have their maximum value, or, as a variant, a second configuration in which said coverings of the orifices have a maximum value, and the diaphragm passage sections have their maximum value;
• the pressure drop values of the oxidant flow rate passing through all of said primary oxidant intake passages and of the diaphragm passages in said first and second configurations are equal;
• said sealing means consist of plates mounted to slide on at least one of the faces of said wall, in a direction parallel to the geometric axis;
• said plates are slidably mounted on the face of said wall opposite to that delimiting the combustion chamber;
• the combustion chamber comprises an annular ring, of axis coincident with said geometric axis, pivotally mounted relative to said wall around this geometric axis, while one of the two sets of parts constituted by the annular ring and by the plates , is provided with a plurality of ramps inclined relative to said geometric axis and that the other set of parts is provided with lugs, each of which is held in abutment on one of the ramps, one lug per ramp;
• each ramp is formed by a groove formed in the set of parts comprising said ramps;
• each of the outer and inner walls is traversed by a plurality of said primary oxidant intake passages, while two annular rings, one outer, the other inner, are associated with said outer and inner walls, respectively, and a single lever is pivotally mounted on a transverse bottom connecting said external and internal walls, around a pivot axis parallel to the geometric axis, and is coupled to said annular rings by means of legs which are integral therewith, so as to synchronize the pivoting commands of the two said annular rings.

The main advantage of the invention resides in the progressiveness of the adjustment relating to the primary oxidant intake orifices, resulting in obtaining satisfactory operating speeds, both with regard to the idling stability, and the reduction of polluting emissions at all operating regimes.

The invention will be better understood, and secondary characteristics and their advantages will become apparent during the description of embodiments given below by way of example.

It is understood that the description and the drawings are given for information only and are not limiting.

• la figure 1 est une vue développée de la face extérieure à l'enceinte de combustion de la paroi externe ou interne d'une première réalisation d'une chambre de combustion annulaire conforme à l'invention, dans une première configuration de fonctionnement de cette chambre de combustion ;
• la figure 2 est une coupe suivant II-II de la figure 1 ;
• la figure 3 est une vue suivant flèche F de la figure 1 ;
• la figure 4 est une vue analogue à la figure 1, de la même chambre de combustion, mais dans une deuxième configuration de fonctionnement ;
• la figure 5 est une coupe suivant V-V de la figure 4;
• la figure 6 est une vue suivant flèche G de la figure 4 ;
• la figure 7 est une vue développée de la face extérieure à l'enceinte de combustion de la paroi externe ou interne d'une deuxième réalisation d'une chambre de combustion annulaire conforme à l'invention, dans une première configuration de fonctionnement de cette chambre de combustion ;
• la figure 8 est une vue analogue à la figure 7, de la même chambre de combustion, mais dans une deuxième configuration de fonctionnement ;
• les figures 9 et 10 schématisent les admissions de comburant de combustion et de comburant primaire des figures 1 et 4;
• la figure 11 schématise les admissions de comburant de combustion et de comburant primaire de la figure 8.

La chambre de combustion partiellement représentée sur les figures 1 à 6 équipe une turbine à gaz et, de type annulaire, comprend une paroi externe 1 et une paroi interne 2, toutes deux sensiblement de révolution d'axe 3. Une paroi transversale 4 relie les parois externe 1 et interne 2, constitue le fond 4 de la chambre de combustion, et définit, avec lesdites parois externe et interne, l'enceinte à l'intérieur de laquelle s'effectue la combustion du carburant.
Plusieurs injecteurs de carburant 5 sont supportés par le fond 4, qu'ils traversent, en étant régulièrement espacés. Des orifices d'admission de comburant de combustion 6 sont associés aux injecteurs de carburant 5, qu'ils entourent, et sont munis, dans les réalisations représentées, de diaphragmes 7 qui permettent de régler les valeurs des sections de passage du comburant, munis à cet effet d'un dispositif de commande schématisé par un levier 8 de commande du pivotement d'une virole 9 d'obturation sélective des trous de passage du comburant. Chaque injecteur de carburant est associé à un diaphragme 7, étant cependant indiqué que, dans sa plus grande généralité, l'invention s'applique également aux chambres de combustion ne comportant pas de diaphragmes, bien que, naturellement, comportant des orifices 6 d'admission de comburant de combustion.Reference will be made to the accompanying drawings, in which:

• Figure 1 is a developed view of the outside face of the combustion chamber of the external or internal wall of a first embodiment of an annular combustion chamber according to the invention, in a first operating configuration of this chamber combustion;
• Figure 2 is a section along II-II of Figure 1;
• Figure 3 is a view along arrow F of Figure 1;
• Figure 4 is a view similar to Figure 1, of the same combustion chamber, but in a second operating configuration;
• Figure 5 is a section along VV of Figure 4;
• Figure 6 is a view along arrow G of Figure 4;
• FIG. 7 is a developed view of the face external to the combustion chamber of the external or internal wall of a second embodiment of an annular combustion chamber according to the invention, in a first operating configuration of this chamber combustion;
• Figure 8 is a view similar to Figure 7, of the same combustion chamber, but in a second operating configuration;
• Figures 9 and 10 show schematically the intake of combustion oxidant and primary oxidant of Figures 1 and 4;
• FIG. 11 diagrams the admissions of combustion oxidant and of primary oxidant of FIG. 8.

The combustion chamber partially shown in FIGS. 1 to 6 equips a gas turbine and, of the annular type, comprises an external wall 1 and an internal wall 2, both substantially of axis revolution 3. A transverse wall 4 connects the external 1 and internal 2 walls, constitutes the bottom 4 of the combustion chamber, and defines, with said external and internal walls, the enclosure inside which the combustion of the fuel takes place.
Several fuel injectors 5 are supported by the bottom 4, which they pass through, being regularly spaced. Combustion oxidizer intake orifices 6 are associated with the fuel injectors 5, which they surround, and are provided, in the embodiments shown, with diaphragms 7 which make it possible to adjust the values of the passage sections of the oxidizer, provided with this effect of a control device shown diagrammatically by a lever 8 for controlling the pivoting of a ferrule 9 for selective closure of the oxidizer passage holes. Each fuel injector is associated with a diaphragm 7, it being however indicated that, in its greatest generality, the invention also applies to combustion chambers not comprising no diaphragms, although, naturally, having orifices 6 for admission of combustion oxidant.

The external wall 1 is further provided with first orifices 10, of oblong shapes, each having two selvedges 11 parallel to the axis 3 and joined by two semicircles 12, therefore having an axis contained in a radial plane passing through the axis 3. Outside the combustion chamber, plates 13 for selective shutter are slidably mounted parallel to the axis 3, sliding on the external face 1A of the external wall 1, being guided to one of their ends by intermediate pads 14 and being covered by a ring 15 for holding on the outer face 1A, and, being guided at their other end by two pins 16 secured to the wall 1. A lug 17, secured of each plate 13, is introduced into a groove 18 formed in an annular ring 19 pivotally mounted around the axis 3. The grooves 18 are helical, and, depending on the pivoting of the ring 19, for example between the configurat ion of FIGS. 1 to 3, and that of FIGS. 4 to 6, constrain the lugs 17, and, the plates 13 of which they are integral, to slide parallel to the axis 3.

Each plate 13 is provided with a second oblong orifice 20, of shapes and dimensions substantially identical to those of a first orifice 10, the axis of which is contained in the radial plane containing the axis 3 and the axis of a first orifice 10. As shown in FIGS. 1 and 2, in the first configuration, each second orifice 20 is superimposed substantially completely on a first orifice 10, so that the passage 21A corresponding to the effective superposition of the orifices 10 and 20 constitutes a primary oxidizer intake passage. This primary oxidizer is added to the combustion oxidant already admitted through the orifices 6 to achieve the most complete possible combustion of the injected fuel. In the second configuration shown in FIGS. 4 and 5, the plates 13 have been moved and brought closer to the bottom 4, so that each second orifice 20 is partly superimposed on the wall 1, which closes it, and, partly a first orifice 10, and constitutes with it a primary oxidant passage 21B of section smaller than that of passage 21A of FIGS. 1 and 2. In addition, the part of each first orifice 10 partially closed by a plate 13 is the part the most distant from the bottom 4, so that in the configuration of FIGS. 4 and 5, not only is the section of each primary oxidant intake orifice 21B smaller than the corresponding section 21A of FIGS. 1 and 2, but also the average location and the extreme location of these primary oxidant intake orifices have come close to the bottom 4.

The internal wall 2 is provided with the same arrangements as those which have just been described with regard to the external wall 1. In particular, an annular ring 22 of axis 3, pivotally mounted around this axis, controls the sliding parallel to the axis 3 of another set of plates 13 slidingly mounted on the face 2A of the internal wall 2, which is external to the combustion chamber. The arrangement is exactly identical to that described with respect to the external wall 1, with the obtaining of passages 21A or 21 B for admission of primary oxidizer similar to those of FIGS. 1,2 and 4,5.

Lugs 19A, 22A secured to the crowns 19, 22 provided with eyes 23, 24 for receiving lugs 25, 26 secured to a lever 27 pivotally mounted on the bottom 4, around a pivot axis 28 parallel to the axis 3, allow the simultaneous controls of the pivoting of the rings 19, 22, respectively, and therefore allow the simultaneous obtaining of the same configuration of the primary oxidizer intake passages, as shown in FIGS. 1 to 3, or, in Figures 4 to 6, or again, an intermediate configuration.

In the case where diaphragms 7 are provided, as in the embodiment of FIGS. 1 to 6, it is further preferred to control these diaphragms simultaneously with the pivoting of the crowns 19 and 22, for example by means of lugs 29 integral with the internal crown 22, provided with eyes 30 into which are introduced lugs 31 integral with the levers 8 for controlling the pivoting of the ferrules 9 of the diaphragms 7. Thus, the pivotings of the rings 19,22 correspond to the pivotings of the ferrules 9 of the diaphragms. The mechanical connections are designed in such a way that the large passages 21A for admission of primary oxidizer correspond to passages of reduced sections of the diaphragms 7 shown diagrammatically in FIG. 9 by thick arrows HA for the passages 21A and by fine arrows JA for the passages 6 of the diaphragms, and, in FIG. 10, by arrows HB fine for passages 21B and by arrows JB thick for passages 6 of the diaphragms. The oxidizer intake passages 21B, of sections smaller than those of passages 21A, are associated with sections of upper passages 6 in FIGS. 4 to 6 and 10, with sections of the same passages 6 in FIGS. 1 to 3 and 9, so that the total pressure drop of the combustion oxidant and primary admitted has a substantially constant value. To note, in FIGS. 9 and 10, the maximum distances DA and DB of the passages 21A and 21B relative to the bottom 4, DB being less than DA.
The embodiment of FIGS. 7 and 8 has the main difference from that of FIGS. 1 to 6, the shape of the second orifices 20A of the plates 13, which is circular, of diameter equal to the spacing of the selvedges 11 of a first orifice. 10, the center of each second orifice 20A then being contained in the radial plane containing a first orifice 10. In this case, the section of the passage 21C for the primary air intake is at most equal to the section of a second orifice 20A, and is effectively equal to this section of a second orifice 20A. On the other hand, the axial location of the passage 21C varies in correspondence with the pivoting of the annular rings for controlling the movement of the plates 13, such as the ring 19 of Figures 7 and 8. The other arrangements of Figures 1 and 3 are found with the same references, in the embodiment of FIGS. 7 and 8.
The arrangements shown first allow the location of the primary oxidant intake passages 21A, 21B and 21C to be adjusted relative to the bottom 4, both in the embodiment of FIGS. 1 to 6, and in that of FIGS. 7 and 8. Thus, the configurations of FIGS. 1 to 3, 7 and 9 correspond to the greatest distance DA, making it possible to obtain a long residence time of the combustion gases in the combustion chamber, which promotes the stability during idling, as well as reduction of carbon monoxide and unburnt hydrocarbon emissions. The configurations of FIGS. 4 to 6, 8, and 10 or 11, correspond to the distance DB less than DA, make it possible to obtain a reduced residence time of the combustion gases, which promotes the reduction of oxides of nitrogen (NOx) during full gas operation.
The provisions of FIGS. 1 to 6 also make it possible to adjust the values of the sections of the primary oxidizer intake passages, which is favorable to the two extreme types of operation: idle and full throttle, under certain specific conditions of use.
According to the embodiment of FIGS. 7 and 8, on the other hand, the values of the sections of the primary oxidant intake passages (21C) are kept identical during the idle operation corresponding to FIG. 9 and during the full gas operation represented by FIG. 11 .
Finally, when the control of the configuration of the primary oxidizer intake passages is combined with the control of the diaphragms (Figures 1 to 6, and 9 and 10, or Figures 7, 8 and 9 and 11), it is possible to keep a constant pressure drop, which is advantageous for obtaining satisfactory operation downstream of the combustion chamber.

As a variant, the grooves 18 could be replaced more generally by support ramps for the lugs 17. Of course, these grooves 18 or these ramps could be formed in the plates 13, the rings 19 and 22 then carrying the lugs 17.

Claims (11)

1. Combustion chamber provided with at least one fuel injector (5) associated with a combustion oxidant inlet device and having a geometrical axis (3), and an outer wall (1) and an inner wall (2), which define an enclosure within which combustion of an oxidant takes place, and of which at least one of these walls is, in particular, provided for this purpose with passages (21A; 21B; 21C) controlling the admission of a primary oxidant into the enclosure; characterized in that the passages comprise first oblong orifices (10), with axes substantially contained in radial planes passing through the geometrical axis (3) of the combustion chamber, and made in the said wall (1); closure means (13), through which second orifices (20; 20A), centred substantially in the same radial planes as the first orifices (10), pass, and a device (19-17-18) for controlling the positions of the said closure means (13) parallel to the said geometrical axis (3), which device can produce controllable overlap of each first orifice (10) by a second orifice (20; 20A), and in that the combustion oxidant inlet device is provided with a diaphragm (7) for controlling the combustion oxidant passages, and a device (8) for controlling the said diaphragm (7), while the commands of the device (19A-23-25-22A-24-26) for controlling the positions of the said closure means (13) and of the device (29-30-31) for controlling the diaphragms (7) are synchronized (27) so as to obtain particular configurations.
2. Combustion chamber according to Claim 1, characterized in that each first orifice (10) includes two parallel edges (11) separated by a determined distance, while each second orifice (20A) has a circular periphery of diameter substantially equal to the said determined distance, the said control of the positions of the closure means (13) producing at least one controllable-position overlap of each first orifice (10) by a second orifice (20A), the value of the passage cross-section (21C) remaining constant.
3. Combustion chamber according to Claim 1, characterized in that each second orifice (20) has an oblong cross-section substantially equal to and of the same shape as that of a first orifice (10), with an axis substantially contained in the radial plane passing through the said geometrical axis (3) and through the axis of a first orifice, while the said overlap has two particular values: a maximum value (Figures 1 and 2) which corresponds to the superposition of the first and second orifices, and a minimum value (Figures 4 and 5) which corresponds to the superposition of only a part of each of the first orifices with a second orifice.
4. Combustion chamber according to any one of Claims 1 to 3, in which the said configurations include a first configuration (Figure 9) in which the said overlaps of the orifices have their maximum value and the cross-sections of the said passages in the diaphragm have their minimum value, and a second configuration in which the said overlaps of the orifices have their minimum value (Figure 10) and the cross-sections of the passages of the diaphragm have their maximum value.
5. Combustion chamber according to either of Claims 1 and 2, in which the said configurations include a first configuration (Figure 9) in which the said overlaps of the orifices have their maximum value and the cross-sections of the said passages of the diaphragm have their minimum value, and a second configuration in which the said overlaps of the orifices have their maximum value (Figure 11) and the cross-sections of the passages of the diaphragm have their maximum value.
6. Combustion chamber according to one of Claims 4 or 5, characterized in that the values of the head loss of the flow of oxidant passing through all of the said primary oxidant inlet passages and the passages in the diaphragm in the said first and second configurations are substantially equal.
7. Combustion chamber according to any one of Claims 1 to 6, characterized in that the said closure means consist of plates (13) mounted so as to slide on one of the faces (1A) of the said wall (1) in a direction parallel to the geometrical axis (3).
8. Combustion chamber according to Claim 7, characterized in that the said plates are mounted so as to slide on that face (1A) of the said wall (1) which is opposite the face delimiting the combustion enclosure.
9. Combustion chamber according to either of Claims 7 and 8, characterized in that it includes an annular ring (19) whose axis coincides with the said geometrical axis (3), mounted so as to pivot with respect to the said wall (1) about this geometrical axis (3) while one (19) of the two sets of parts consisting of the annular ring (19) and of the plates is provided with a plurality of ramps (18) which are inclined with respect to the said geometrical axis (3), and the other set (13) of parts is provided with lugs (17), each of which is kept bearing on one of the ramps (18), one lug per ramp.
10. Combustion chamber according to Claim 9, characterized in that each ramp consists of a groove (18) made in the set (19) of parts including the said ramps (18).
11. Combustion chamber according to either of Claims 9 and 10, characterized in that a plurality of the said primary oxidant inlet passages passes through each of the outer (1) and inner (2) walls, while two annular rings (19, 22), one (19) outer and the other (22) inner, are associated with the said outer and inner walls, respectively, and in that a single lever (27) is mounted so as to pivot on a transverse base (4) connecting the said outer (1) and inner (2) walls, about a pivot pin (28) parallel to the geometrical axis (3) and is coupled to the said annular rings (19, 22) by means of tabs (19A-22A) which are rigidly fixed thereto, so as to synchronize the pivoting commands of the two said annular rings.

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