Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
  • F23R3/04—Air inlet arrangements
  • F23R3/06—Arrangement of apertures along the flame tube

Definitions

• the present invention relates to a combustion chamber of a gas turbine, in particular a gas turbine with thermodynamic cycle with recuperator, for the production of energy, in particular electrical energy.
• It relates more particularly to a microturbine with recuperator for the production of electricity from a liquid or gaseous fuel.
• microturbine is understood to mean a gas turbine of small power usually less than 200KW.
• a gas turbine with recuperator generally comprises at least one compression stage with at least one compressor, a combustion chamber (or burner), at least one expansion stage with at least one expansion turbine, a heat exchange device (or recuperator) between the compressor and the combustion chamber making it possible to heat the gases compressed by the compressor to send them with a high temperature to the combustion chamber, this exchange device being traversed by the hot gases coming from the turbine of relaxation.
• the combustion chamber comprises a housing through which circulates the hot compressed air coming from the recuperator and a flame tube, located inside this box, in which combustion takes place.
• the flame tube comprises a primary zone which receives part of the total hot compressed air flow and in which combustion takes place thanks in particular to ignition electrodes, and a dilution zone where the mixing takes place between the burnt gases. from the primary zone and hot compressed gases from dilution holes provided on the flame tube.
• the primary zone also includes a perforated diffuser allowing the passage of hot compressed air as well as fuel coming from a fuel injection system (liquid or gaseous) placed upstream of the diffuser.
• the flame tube carries a flame stabilizer comprising the perforated diffuser, at least one flue gas recirculation passage and a mixing tube.
• the compressed air from the compressor enters through a tube located above the housing and is distributed in the combustion chamber in two flows.
• a first air flow is directed indirectly to the primary zone where combustion takes place and for this purpose it passes through the perforated diffuser described above.
• a second flow will enter directly into the dilution zone of the flame tube via the dilution holes (or openings) distributed over one or more rows and of identical diameter to obtain, at the outlet of the combustion chamber, a homogeneous mixture in temperature. and composition.
• This combustion chamber although satisfactory, nevertheless presents significant drawbacks linked in particular to an asymmetry of the flow in the flame tube of the combustion chamber, that is to say in the primary zone and in the zone dilution.
• the asymmetry in the dilution zone is linked to the fact that the flow rate of the second air flow entering the dilution zone through the dilution openings is greater at the bottom of the flame tube than at the top of it, causing asymmetry in the dilution zone.
• the presence of electrodes in the path of the first flow modifies the flow around the flame catch and the recirculations, so that the rate of dilution by the gases burned is different between the upper and lower parts of the dilution zone.
• the flow enters with a non-homogeneous speed and flow in the primary zone. This is caused by a movement of preferential flows in the room.
• the incoming compressed air surrounds the flame tube and generates a greater air flow at the bottom than at the top. This results in a flow towards the primary zone more important in the lower part. The result is a higher preferential inlet flow from the bottom of the perforated diffuser, producing an asymmetry.
• the objective of the present invention is to compensate for the asymmetry in order to standardize the flows entering the flame tube by limiting in particular the differences in upper and lower flows, and this in order to improve the localization of the hot zones, to have better durability of the parts as well as a better homogeneity of the temperature leaving the combustion chamber, having a design at a lower cost and allowing more dilute combustions and a further reduction in CO and HC emissions.
• a first aspect of the invention relates to a combustion chamber of a gas turbine, in particular of a gas turbine with thermodynamic cycle with recuperator, for the production of energy, in particular electrical energy, comprising a housing with means for injecting at least one fuel and an inlet for hot compressed air, said housing housing a flame tube and the invention is characterized in that the flame tube comprises at least one circumferential row d radial dilution holes and the passage surface of the radial dilution holes lying above a plane P is greater than the passage surface of the radial dilution holes lying below the plane P, said plane P is a plan which cuts the flame tube in the length, which passes through the center of it and oriented so that the radial dilution orifices located above the plane P are opposite the hot compressed air intake.
• said plane P is substantially parallel to a theoretical plane PT which is the plane formed by an opening created in the case for the admission of hot compressed air.
• said flame tube comprises a perforated diffuser for the passage of hot compressed air and fuel
• said perforated diffuser comprises axial diffusion holes distributed circularly and the total surface of the axial holes lying above the plane P is greater than the total area of the axial holes lying below the plane P.
• the flame tube comprises a primary zone (ZP) and a dilution zone (ZD) and the circumferential row of radial dilution orifices is positioned at the start of the dilution zone (ZD).
• the flame tube comprises a narrowing zone which is positioned upstream of said circumferential rows of radial dilution orifices.
• the narrowing zone of the section of said flame tube comprises an obstacle of symmetry of revolution.
• the obstacle of symmetry of revolution comprises a ring positioned in the flame tube.
• the narrowing zone includes a change in diameter of the flame tube upstream of the dilution zone (ZD).
• the combustion chamber comprises an air deflector disposed opposite the intake of hot compressed air.
• a second aspect of the invention comprises a gas turbine, in particular a gas turbine with thermodynamic cycle with recuperator, for the production of energy, in particular electrical energy, comprising at least one compression stage with at least a gas compressor, a heat exchanger, a combustion chamber, and at least one expansion stage with at least one expansion turbine, and the gas turbine is characterized in that it comprises a combustion chamber as described previously.
• FIG. 1 is a diagram illustrating a microturbine with a combustion chamber according to the invention for the production of energy, in particular electrical energy;
• FIG. 2 is a perspective view of a flame tube according to the invention.
• FIG. 3 is a sectional view in a plane P1 of a perforated diffuser according to the invention.
• FIG. 4 is an axial sectional view of an embodiment of a combustion chamber.
• a microturbine 10 comprises at least one compression stage 12 with at least one gas compressor 14, a heat exchanger 16 (or recuperator), a combustion chamber 18 (or burner) supplied with fuel by at least one tank 20, at least one expansion stage 22 with at least one expansion turbine 24 connected by a shaft 26 to the compressor 14.
• This turbine also comprises a means of producing energy , here electric, which includes an electric generator 28 advantageously placed on the shaft 26.
• the electric generator 28 is placed between the compressor and the turbine.
• this electric generator 28 can be alternately connected to the expansion turbine 24 or to the compressor 14 by a shaft other than that connecting the turbine and the compressor 14.
• the heat exchanger 16 can be a cross-flow exchanger, for example of the shell-tube or alternating plate type with two inlets and two outlets.
• the compressor 14 comprises an inlet 30 for fresh gas containing oxygen, here outside air generally at room temperature, and an outlet for compressed air 32 leading to an inlet for compressed air 34 of the exchanger 16 by a line 36.
• the hot compressed air outlet 38 of this exchanger is connected by a line 40 to a hot compressed air inlet 42 of the burner 18.
• the superheated gas outlet 44 of the burner is connected by a line 45 to the 'inlet 46 of the turbine, the outlet 48 of which is connected to another inlet 50 of the exchanger by a line of expanded superheated gases 52.
• the exchanger 16 also includes an outlet of cooled gases 54 to be directed to all means of evacuation and treatment, such as a chimney (not shown).
• the invention relates generally and initially of dilution orifices (also called holes or openings) positioned on the flame tube 122 which are of different diameters unlike the state of the art described above where the dilution orifices are all of identical diameter. Dilution orifices of different diameters make it possible to limit the differences between the upper and lower flows and make it possible to standardize the flows entering the flame tube 122.
• the flame tube 122 generally comprises a primary zone ZP in which combustion takes place, and a dilution zone ZD in which the mixing takes place between the burnt gases from the primary zone and the compressed air. hot.
• the invention will consist in particular in reducing or increasing the diameter of said dilution holes as a function of the orientation of the flows entering the flame tube 122 and in particular in the dilution zone (ZD).
• the increase in the diameter of the dilution orifices is done on the side where the hot compressed air opens onto the flame tube 122 and the reduction in the diameter of the dilution orifices is done on the opposite side where the hot compressed air opens on the flame tube.
• FIG. 2 represents, without limitation, a flame tube 122 in a first embodiment contained in a combustion chamber 18.
• the flame tube 122 comprises a circumferential row of radial dilution orifices 166 which allow the passage of hot compressed air into the dilution zone ZD.
• These radial dilution orifices 166 are of different diameters.
• this comprises several circumferential rows of radial dilution orifices 166 which are also of different diameter.
• the invention also relates, as a second step, to holes (also called orifices or openings) for axial diffusion 158 of a perforated diffuser 156.
• holes also called orifices or openings
• FIG. 3 in a nonlimiting manner, which represents a perforated diffuser 156 according to a view in a plane P1 visible in FIG. 4, electrodes 500 are placed near and above said perforated diffuser 156. As explained previously, they disturb the flow which passes through the perforated diffuser 156.
• This perforated diffuser 156 includes axial diffusion holes 158 of different diameter in order to compensate for the asymmetry of the flow.
• the combustion chamber 18 illustrated without limitation in Figure 4, it comprises a housing 112 of cylindrical shape with a tubular wall 1 14 of substantially circular section. This box is closed at one end by a bulkhead injector 1 16 and at the other of its ends by an annular partition 1 18 with a substantially circular opening 120.
• This combustion chamber also comprises a flame tube 122, also of substantially cylindrical shape, housed coaxially in the housing being of diameter smaller than the housing but of diameter identical to that of the opening 120 of the annular partition.
• This tube comprises a wall 124 of substantially circular section, one end closed by a diffusion partition 126 facing and at a distance from the injector partition 11 16, and an open end 128 which passes through the annular partition by cooperating with sealing with the internal diameter of this annular partition to form the outlet 130 of this combustion chamber.
• the housing 1 12 carries on its peripheral wall 1 14, a hot compressed air intake 132.
• a hot compressed air intake 132 In the embodiment shown in Figure 4 it is positioned substantially at equal distance between the injector bulkhead and the annular bulkhead .
• the hot compressed air inlet 132 can be placed at any location on the peripheral wall 114 of the housing 1 12. Likewise, this may have any orientation and is not necessarily orthogonal to the housing 1 12.
• the passage surface of the radial dilution holes 166 facing the inlet of hot compressed air 132 is greater than the passage surface of the radial dilution holes 166 located at the opposite of the hot compressed air inlet 132.
• the radial dilution holes 166 facing the inlet of hot compressed air 132 are located above a plane P and the radial dilution holes 166 being opposite the inlet of hot compressed air 132 is located below plane P.
• the plane P is defined as the plane which cuts the flame tube 122 lengthwise and which passes through the center of it. As visible in FIG. 4, this plane P is also a plane of axial symmetry of the combustion chamber and it is horizontal in the embodiment described. To enable the limit of the radial dilution holes 166 lying below or above to be defined, this plane P is substantially parallel to a theoretical plane PT.
• This theoretical plane PT is the plane formed by an opening 600 created in the housing 12 for the admission of hot compressed air 132. In the case where the housing is cylindrical, the plane PT is tangent to the opening at the level of the lowest points of the opening 600 formed.
• the passage surface is 20% greater at the top of the plane P relative to the bottom of the plane P.
• an air deflector 134 is placed between the two walls 1 14 and 124 and opposite this air intake to circulate this hot air in one axial direction from this admission.
• this deflector 134 comprises a tube 136 open at each of its ends 138, 140.
• This tube comprises a tubular fixing portion 142 and a tubular air diversion portion 144, of different section, connected together by a junction portion 146, here of frustoconical shape.
• the section of the tubular portion of larger section 142 which corresponds to the tubular fixing portion, has an outside diameter substantially equal to that of the inside diameter of the housing 1 12 while the section of the tubular portion of smaller section 144, which corresponds to the tubular air diversion portion, has an outside diameter which is larger than the outside diameter of the wall 124 of the flame tube 122 and smaller than that of the inside diameter of the wall 1 14 of the housing 1 12.
• This deflector 134 is housed in the combustion chamber 18 in such a way that the tubular fixing portion 142 is housed between the injector bulkhead 11 16 and the diffusion bulkhead 126 while being fixed by any known means (soldering, welding , ..) to the wall of the housing 1 12, that the tubular air bypass portion 144 is located substantially opposite the air intake 132 and that the frustoconical portion 146 is placed near this intake.
• the diameter of the tubular air bypass portion is such that it is equivalent to the average of the diameters of the housing 12 and of the flame tube 122. This makes it possible to create circulation passages for the compressed air of same radial height R between this portion and respectively the housing (passage 148) and the flame tube (passage 150).
• the open end 140 of the tubular air bypass portion 144 is located at a distance from the annular partition 11 so that the distance between this open end and the partition creates a connecting passage 151 of which the axial dimension D is at least equal to the radial height R.
• the injector-carrying partition carries a means for injecting at least one fuel 152, here in the form of an injector coaxial with the flame tube 122, opposite a stabilizer flame 154 which is placed on the diffusion wall 126.
• This stabilizer 154 comprises the perforated diffuser 156 of FIG. 3 housed in the diffusion wall 126 and comprising a multiplicity of axial holes 158 regularly distributed circumferentially on the sole and a central axial orifice 160.
• the surface of the axial holes 158 lying above the plane P is greater than the surface of the axial holes 158 lying below the plane P. In this way the asymmetry of the flows is compensated.
• the circumferential rows of radial dilution orifices 166 are placed at a distance from the diffusion partition and close to the annular partition of the housing 1 12, being regularly distributed advantageously on either side of the free end region of the portion 144.
• the flame tube 122 also includes an obstacle of symmetry of revolution. This obstacle can in particular be a ring 200 inserted in the flame tube 122 and of symmetry of revolution.
• This ring 200 has a diameter less than the diameter of the flame tube 122.
• the thickness of the ring is between a few millimeters and a few centimeters.
• the combustion chamber 18 thus formed comprises an injection / mixing zone ZM where the hot compressed air is mixed with the fuel and the start of combustion, a primary zone ZP in which combustion takes place, and a dilution zone ZD where the mixing takes place between the burnt gases coming from the primary zone ZP and the hot compressed air coming from the dilution holes 166.
• the ring 200 is positioned between the primary zone ZP and the dilution zone ZD. This ring 200 is positioned with respect to the dilution holes 166 so as to block the counter-current flows in the primary zone ZP, that is to the left of the dilution holes 166 in FIG. 3.
• the flame tube 122 has a particular geometry which consists in having a narrowing zone or a sudden change takes place diameter of the flame tube 122.
• This narrowing zone is positioned upstream of the dilution zone ZD and before the dilution holes 166 so as to block the countercurrent flows in the primary zone ZP, that is to say to the left of the dilution holes 166 in Figure 4.
• the fuel here in liquid form, is injected by the injector 152 in the direction of the diffusion wall 126 to pass through the central orifice 160.
• the hot compressed air coming from the inlet 132 is deflected by the deflector 134 according to arrow F1 in the first place by the frustoconical portion 146 to end up in the passage 148.
• This air circulates in an axial direction starting from the admission 132 and throughout this passage 148 according to a single direction of circulation, here from left to right considering arrow F2 to arrive at the end passage 151. Arrived at this passage, the air has a direction of radial circulation according to arrow F3 then circulates in passage 150, in an axial direction opposite to that of passage 148 according to arrow F4.
• the flow of air from the intake is directed towards the side opposite to the mixing zone before returning to this mixing zone by surrounding the tubular air bypass portion 144.
• the velocities of arrival of the air in the space located in the tubular air bypass portion 144 are low and more symmetrical (symmetry of revolution) with respect to the central axis of the tubular bypass portion of air, which improves the efficiency of the dilution. Indeed, in each of the different rows of dilution holes 166, the air entry velocities in the dilution zone are close for all the holes;
• the velocities of arrival in the zone located between diffusion partition 126 and the box 1 12 are very low due to the large section of the mixing zone ZM and the relatively low flow (part of the total flow leaves in the zone of ZD broadcast).
• This zone behaves like a collector making it possible to have entry speeds into the main zone ZP via the diffusion wall which are normal to the wall and which are identical for each concentric row of holes. In this, the flame then generated in the primary zone ZP is located well around the axis of the tubular air bypass portion.
• the flame tube 122 does not include a ring 200.
• the latter does not include a deflector 134.
• the modification according to the invention thus makes it possible to effectively re-center the flame, all this while modifying only very little the combustion chamber 18.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

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• 2018
  • 2018-07-30 FR FR1857059A patent/FR3084447B1/fr not_active Expired - Fee Related
• 2019
  • 2019-07-01 WO PCT/EP2019/067574 patent/WO2020025233A1/fr unknown
  • 2019-07-01 EP EP19734803.0A patent/EP3830485A1/de not_active Withdrawn

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