JP2003343839A - Promoted mixture combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve homogenization of premix gas and reduce NOx by promoting mixture of air and fuel gas in a combustion chamber. <P>SOLUTION: A promoted mixture combustor comprises: a cylindrical flame tube 3 having a combustion space in the interior with one end closed and the other end opened; an air spray pipe 4 connected to the side of the flame tube near the one end; and a fuel gas supply pipe 6 connected to one end face of the flame tube. An inner circumference of the flame tube has a plurality of projections 8 projecting into the flame tube. The air spray pipe sprays air in a tangential direction of the flame tube. The fuel gas supply pipe sprays fuel gas in the axial direction of the flame tube. The air and fuel gas are formed into a swirl α along the inner circumference of the flame tube, and are agitated into tumbles β when involved downstream of the projections. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixing promotion combustor used for a gas turbine or the like, and more specifically, for promoting mixing of air supplied to a combustion chamber of a gas turbine and a fuel gas with a preliminary The present invention relates to a mixing promotion combustor capable of improving the homogeneity of an air-fuel mixture and reducing NOx.

[0002]

2. Description of the Related Art FIG. 7 is a schematic diagram of a gas turbine engine, which includes an air intake 51, a compressor 52, and a combustor 5.
0, a turbine 54, an afterburner 55, a jet nozzle 56, and the like. In such a gas turbine engine, air is introduced from the air intake port 51, the air is compressed by the compressor 52, the fuel is burned in the combustor 50 to generate high temperature combustion gas, and the generated combustion gas is used as a gas. The turbine 54 is driven, and the gas turbine 54 drives the compressor 52.
The fuel is re-combusted by the exhaust gas discharged from the turbine by the afterburner 55, and the high temperature combustion exhaust gas is expanded by the jet nozzle 56 and ejected rearward to generate a propulsive force.

As shown in the longitudinal sectional view of FIG. 8, the combustor of this gas turbine engine has a frame tube 57 having a combustion space inside and a constant gap between the frame tube and the frame tube. Air casing 5 to cover this
8 and. Further, a snout portion 60 for taking in air, which is a mainstream gas, into the combustor is formed at the upstream end of the frame tube 57, and an exhaust port 59 for sending combustion exhaust gas to a turbine (not shown) is opened at the downstream end. is doing.

Most of the mainstream gas (air) sent from the compressor through the mainstream gas flow passage 63 is taken into the combustion chamber from the snout section 60 and used for combustion. The remaining air passes through a gap between the frame tube 57 and the air casing 58 to cool the frame tube, and
The secondary air hole 61 provided in the frame tube 57 enters the combustion chamber and is used to promote re-combustion.

The combustor 50 is connected to a mainstream gas pipe 63 through which a fuel gas supply pipe 62 is passed, and the fuel gas supply pipe 62 is disposed substantially at the center of the mainstream gas flow path along the flow thereof and burns. A jet nozzle 64 for spreading the fuel gas over a wide area and jetting it to the entrance of the chamber
Is equipped with.

In order to improve the combustion efficiency in the combustion chamber and to reduce NOx by complete combustion, it is desirable that the main gas, air, and fuel gas be sufficiently mixed and burned. However, since compressed air flows at high speed, a gas turbine having a short axial length cannot secure a generation time of a mixed gas, and if the mainstream gas is simply poured into the fuel gas ejected into the combustion chamber, the mixture will be mixed. It may be insufficient.

Therefore, in a general gas turbine engine, a swirl vane having a plurality of vanes which are arranged radially in the mainstream gas flow path near the ejection nozzle 64 in a state of being inclined with respect to the axial direction and which form a blade row. (Swirl vane
s) 65 was attached and the mainstream gas taken in from the snout 60 was swirled in the circumferential direction. The mainstream gas that has been swirled (α ′) by the swirl vanes is introduced into the combustion chamber, and the fuel gas ejected from the ejection nozzle 64 is also drawn toward the combustion chamber to stir the fuel gas and promote its mixing. However, the generation time of the mixed gas was shortened.
When the mixing of the fuel gas and the air is promoted, the generation of NOx is reduced as compared with the case where the mainstream gas (air) is simply poured into the fuel gas ejected into the combustion chamber.

[0008]

However, in the above-described conventional mixing mechanism using the swirl vanes 65, the mixing is still insufficient because the mixing is promoted only by the swirling flow (α ') of the swirl vanes, and rapid mixing is performed. It could not be said that the reduction of NOx in the combustion exhaust gas by the premixed combustion using was achieved sufficiently. Further, in the conventional combustor, the frame tube 57 and the air casing 58 are
Although the frame tube was cooled by introducing air into the space between and, the cooling effect was still insufficient.

The present invention was created to solve such problems. That is, the first object of the present invention is to provide a mixing promotion combustor capable of improving the homogeneity of the air-fuel mixture and promoting NOx reduction by promoting the mixing of air and fuel gas in the combustion chamber. Especially.

Another object of the present invention is to provide a mixing promotion combustor which can also effectively achieve cooling of a flame tube having a combustion space inside.

[0011]

According to the present invention, a cylindrical frame tube (3) having a combustion space inside which is closed at one end and opened at the other end is connected to a side surface near the one end of the frame tube. And a fuel gas supply pipe (6) connected to one end surface of the frame tube. The inner peripheral surface of the frame tube is provided with a plurality of protrusions toward the inside of the frame tube. Protrusions (8) are provided, air is ejected from the air ejection pipe in the tangential direction of the frame tube, fuel gas is ejected from the fuel gas supply pipe in the axial direction of the frame tube, and air and fuel gas are discharged. , A swirling flow (α) is formed along the inner peripheral surface of the frame tube, and a vertical vortex (β) is generated by the entrainment on the downstream side of the protrusion to be stirred.
A mixing promotion combustor is provided.

According to the structure of the present invention, the fuel gas ejected in the axial direction of the combustor is sheared by the air ejected in the tangential direction and then swirls along the inner peripheral surface of the combustor. , The mixing of air and fuel gas is promoted. In addition, since the surface through which the gas flows, that is, the inner circumferential surface of the combustor is concavely curved in the main flow direction, the laminar boundary layer on that surface has a vortex (Geltra vortex) similar to the Taylor vortex due to the unstable phenomenon due to centrifugal force. (Vortex) is generated, and the mixing of air and fuel gas is promoted by this vortex. Further, a vertical vortex is generated due to the entrainment on the downstream side of the protrusion provided on the inner peripheral surface of the combustor, and the vertical vortex agitates the mixed gas of air and fuel gas, so that uniform mixing is further promoted. It

Here, an air casing (14), which has a constant space (12) serving as a gas flow path and covers the frame tube (3) and covers the same, is further provided, and each of the protrusions (8). A gas discharge port (16) for discharging the air sent through the gap into the frame tube at the root of the
It is also preferable that the air is discharged from the gas discharge port and the air discharged from the gas discharge port is used for combustion of the fuel gas and the frame tube is cooled.

By discharging air into the frame tube from the gas discharge port formed at the base of the protrusion, the air supplied from the air ejection pipe as well as the air supplied from the gas discharge port burns fuel gas. Can be used for.
Further, since the protrusions can be provided on almost the entire inner peripheral surface of the frame tube, the inner peripheral surface of the frame tube can be cooled by covering the inner peripheral surface of the frame tube with the air discharged from the gas discharge port. The air discharged from the gas discharge port is sent through the space between the frame tube and the air casing that covers the frame tube as a flow path. Further, the frame tube is also cooled from the outer peripheral side by the air flowing through the gap. It is preferable that the gas discharge port is perforated at the root portion located on the downstream side of the protrusion in order to reduce the loss of the mixed gas flow.

Further, according to the present invention, a cylindrical frame tube (3) having one end closed and the other end open and having a combustion space inside, and a fixed space (12) serving as a gas flow path between the frame tube and the frame tube. And an air jetting pipe (4) connected to a side surface near one end of the frame tube, the inner surface of the frame tube being directed toward the inside of the frame tube. A plurality of protrusions (8) are provided, and a gas discharge port (16) for discharging the fuel gas sent through the gap into the frame tube is bored at the root of each protrusion. Air is ejected from the air ejection pipe in a tangential direction of the frame tube, fuel gas is ejected from the gas ejection port into the frame tube, and the air and the fuel gas are ejected from the frame tube. Swirling flow along the inner peripheral surface and with becomes (alpha), it is stirred produce longitudinal vortex (beta) by entrainment in the downstream side of the protrusion, to provide a mixing promotion combustor, characterized in that.

In the present invention, the fuel gas is not jetted and supplied in the axial direction of the frame tube from the fuel gas supply pipe connected to the upstream end of the frame tube as in the above-described combustor, but is supplied to the root of the protrusion. The fuel gas is supplied from the perforated gas discharge port. The fuel gas supplied from the gas outlet into the frame tube is mixed with the air flowing along the inner peripheral surface of the frame tube in a swirling flow, and the swirling flow is generated by the vertical vortex generated by the entrainment on the downstream side of the protrusion. Stir to facilitate the mixing.

Here, the shape of the protrusion (8) in the preferred embodiment is such that the height of the swirling flow (α) gradually increases gradually from the upstream side and the height thereof rapidly decreases on the downstream side. A part of the shape frame tube (3) having a tetrahedron shape having a height gradually increasing and a width gradually decreasing from the upstream side to the downstream side of the swirling flow (α), and a part of the shape frame tube (3) is a frame The shape is formed by bending toward the inside of the tube, and the height of the swirling flow (12) gradually increases from the upstream side.

By making the height of the protrusion gradually increase from the upstream side of the swirl flow, the loss of the mixed gas flow due to the protrusion can be reduced. In addition, the protrusion has a shape in which its height is sharply reduced at the downstream end thereof, so that a vertical vortex is generated on the downstream side of the protrusion, and the vertical vortex stirs air and fuel gas to promote mixing. However, the generation time of the mixed gas can be shortened. In addition, the above-mentioned protrusion is formed by making a cut in a part of the frame tube and bending it, and the hole opened in the frame tube by bending is used as a gas discharge port.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same parts are denoted by the same reference numerals.

FIG. 1 is a schematic configuration diagram of a combustor of the first embodiment, and FIG. 1 (a) is a radial sectional view of the combustor.
(B) is an axial sectional view of the combustor.

This combustor is used for a gas turbine. A compressor for compressing air taken into the engine is arranged on the upstream side, and a gas turbine driven by combustion gas is arranged on the downstream side. (Not shown). The combustor rapidly mixes high-speed compressed air and fuel gas inside and burns them to generate high-pressure compressed gas required by the turbine. Achieving low NOx in the gas.

This combustor 10, as shown in FIG.
An outer space is defined by a cylindrical frame tube 3 having an upstream end closed and an exhaust port 1 formed at a downstream end, and a space serving as a combustion chamber 2 in which a mixed gas of air and fuel gas is burned. Is provided. Frame tube 3
An air ejection pipe 4 for ejecting air compressed by a compressor (not shown) toward the combustion chamber 2 at high speed is connected to the side surface on the upstream end side of the. A fuel gas supply pipe 6 for ejecting fuel gas to the combustion chamber 2 is connected to the upstream end of the frame tube 3 and has an ejection nozzle 5 at its tip.

Here, on the inner peripheral surface of the frame tube 3,
A plurality of protrusions 8 that protrude toward the inside of the frame tube are provided. The protrusions 8 are provided in a zigzag pattern on the entire inner peripheral surface of the frame tube 3.

FIG. 2 shows an enlarged view of the protrusion. The protrusion has a shape in which the height thereof smoothly increases gradually from the upstream side of the swirling flow, and the height thereof sharply decreases on the downstream side (FIG. 2A).
Alternatively, it has a tetrahedron shape having a height that gradually increases from the upstream side to the downstream side and a width that gradually decreases, and has a shape in which the side wall thereof is a bluff (FIG. 2B).

Air is jetted from the air jet pipe 4 in the tangential direction of the frame tube, and the fuel gas is jetted from the jet nozzle 5 of the fuel gas supply pipe 6 in the axial direction of the frame tube. The connection point of the fuel gas supply pipe 6 is located radially inward from the outer peripheral side of the upper end of the frame tube, and the fuel gas is jetted from the air jet pipe 4 near the laminar boundary layer of the air jetted at high speed.

The fuel gas ejected from the ejection nozzle 5 at the tip of the fuel gas supply pipe in the axial direction of the frame tube 3 is sheared by the air ejected from the air ejection pipe 4 in a tangential direction of the frame tube at a high speed and in a large amount, It heads toward the exhaust port 1 on the downstream side of the combustor 10 while making a large swirl along the inner peripheral surface of the combustion chamber 2. The sheared fuel gas is primarily mixed with air by being agitated, and swirling in the combustion chamber 2 further promotes its mixing by the above-mentioned Gertra vortex.

The mixed gas spirally flowing on the inner peripheral surface of the frame tube 3 advances along the inclination of the protrusion 8 by the protrusion 8 as shown by the arrow in FIG. Small vertical vortex (β) due to entrainment on the downstream side of the part
Cause This vertical vortex further agitates the mixed gas of air and fuel gas to promote secondary mixing. When the mixing is promoted, the homogeneity of the air-fuel mixture is improved, so that the generation of NOx is also reduced.

Since the height of the protrusion smoothly increases gradually from the upstream side of the swirling flow, the loss given to the mixed gas flow is small.

FIG. 3 shows a schematic diagram of the combustor of the second embodiment. Here, FIG. 2A is a radial cross-sectional view,
(B) is an axial sectional view.

The combustor 20 is different from the combustor 10 of the first embodiment in that it further includes an air casing 14 which has a constant space 12 which serves as a gas flow path between the combustor 10 and the frame tube 3 and covers the same. A gas discharge port 16 that discharges air into the combustion chamber is formed on the downstream side of the root of the protrusion 8 having the shape described above (FIG. 4).

In this combustor 20, as in the combustor of the first embodiment, air flows from the air ejection pipe 4 to the frame tube 3
Is ejected in the tangential direction, and the fuel gas is directed from the injection nozzle 5 of the fuel gas supply pipe 6 in the axial direction of the frame tube.
Further, as in the first embodiment, the fuel gas is jetted from the air jet pipe 4 to the vicinity of the laminar boundary layer of the air jetted at high speed and sheared. The mixed gas of air and fuel gas becomes a large swirling flow (α) in the frame tube, and is agitated by the small vertical vortex (β) generated on the downstream side of the protrusion, which promotes its mixing. Is similar to the combustor of the first embodiment.

In the combustor 20 of this embodiment, the space 1 between the frame tube 3 and the air casing 14 covering the frame tube 3 is
2 is used as a flow path, and air is sent to a gas discharge port 16 that is bored in the root portion of the protrusion 8, and from there, air is discharged so as to flow along the inner peripheral surface of the frame tube 3 as much as possible, It is characterized in that the inner peripheral surface of the frame tube is covered with a film to cool it. In addition, in order to reduce the loss given to the mixed gas flow, the gas discharge port 16 is perforated at the base portion located on the downstream side of the protrusion 8 as shown in FIG. Further, the frame tube 3 is also cooled from the outer peripheral side thereof by the air flowing through the gap 12. The air discharged from the gas discharge port 16 is also used for combustion of fuel gas.

FIG. 5 shows a schematic block diagram of the combustor of the third embodiment. The combustor 30 of the present embodiment is a modification of the method of supplying the fuel gas that has been injected in the axial direction of the frame tube 3 from the injection nozzle 5 of the fuel gas supply pipe 4 in the combustor 10 of the first embodiment. is there.

In this embodiment, as in the second embodiment, the gas discharge port 16 is bored at the base of the protrusion. In the combustor 20 of the second embodiment, air is emitted from here,
In the combustor 30 of this embodiment, the fuel gas is discharged from here and the fuel gas is supplied into the combustion chamber. The fuel gas is discharged in the central axis direction of the frame tube. The fuel gas supplied from the gas discharge port 16 into the combustion chamber is discharged into the turbulent vortex region due to the vertical vortex (β) generated on the downstream side of the protrusion, and is sheared and agitated by the air swirling along the inner peripheral surface of the frame tube. -Swirled and mixed temporarily. Further, the swirling mixed gas of air and fuel gas is secondarily stirred by the generation of small vertical vortices (β) due to entrainment on the downstream side of the plurality of protrusions 8 ′, thereby promoting the mixing. To be done.

Here, the projection 8'is formed by forming a V-shaped cut on the wall surface of the cylindrical frame tube 3 as shown in FIG. 6 and pushing it toward the combustion chamber. . The height of the projection 8'formed in this manner gradually increases from the upstream side of the swirl flow 12, and a gas discharge port 16 for discharging the fuel gas is opened at the root of the projection 8 '. . The protrusions 8 ′ are provided in a zigzag pattern on the entire inner peripheral surface of the frame tube 3. When the fuel gas is supplied from a wide range, it becomes easier to mix the air and the fuel gas. In addition, the fuel gas is sent to the gas discharge port 16 of the protrusion using the gap 12 between the frame tube 3 and the air casing 14 as a flow path. The protrusions may have the shape shown in FIG.

As described above, the combustor according to this embodiment can also promote the mixing of the fuel gas and the air. Also,
By ejecting the fuel gas from the entire inner peripheral surface of the frame tube 3, a cooling effect of the frame tube can be expected.

As described above, the present invention can reduce the generation of NOx by promoting the mixing of air and fuel gas and improving the homogeneity of the air-fuel mixture. Further, when air or fuel gas is jetted from the root of the protrusion, the frame tube can be cooled.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, the present invention can be applied as a combustor or a rapid premixer used in a boiler or a furnace.

[0039]

As described above, according to the combustor of the present invention, the mixing of air and fuel gas is promoted, the combustion efficiency in the combustor is improved, and the NOx contained in the combustion gas is reduced. You can Further, when air or fuel gas is discharged from the root of the protrusion, it is possible to cool the frame tube at the same time.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a combustor of a first embodiment.

FIG. 2 is an enlarged view of a protrusion according to the first embodiment.

FIG. 3 is a conceptual diagram of a combustor of a second embodiment.

FIG. 4 is an enlarged view of a protrusion according to a second embodiment.

FIG. 5 is a conceptual diagram of a combustor of a third embodiment.

FIG. 6 is an enlarged view of a protrusion according to a third embodiment.

FIG. 7 is a schematic configuration diagram of a gas turbine engine.

FIG. 8 is a vertical cross-sectional view of a combustor of a conventional gas turbine engine.

[Explanation of symbols]

1 exhaust port 2 combustion chamber 3 frame tubes 4 Air ejection pipe 5 jet nozzle 6 Fuel gas supply pipe 8 protrusions 8'projection 10 Combustor 12 voids 14 Air casing 16 gas outlet 20 Combustor 30 Combustor 50 Combustor 51 air intake 52 Compressor 54 turbine 55 Afterburner 56 jet nozzle 57 frame tubes 58 Air casing 59 Exhaust port 60 snout section 61 Secondary air hole 62 Fuel gas supply pipe 63 Mainstream gas pipe 64 jet nozzle 65 swirl vanes α swirl flow β vertical vortex

Claims (6)

[Claims] 1. A cylindrical frame tube (3) having one end closed and another end open with a combustion space, and an air ejection pipe (4) connected to a side surface near one end of the frame tube, A fuel gas supply pipe (6) connected to one end surface of the frame tube, and a plurality of protrusions (8) protruding toward the inside of the frame tube are provided on an inner peripheral surface of the frame tube, Air is ejected from the air ejection pipe in the tangential direction of the frame tube, fuel gas is ejected from the fuel gas supply pipe in the axial direction of the frame tube, and air and fuel gas are distributed along the inner peripheral surface of the frame tube. A mixing promotion combustor, which is a swirl flow (α) and is stirred by generating a vertical vortex (β) due to entrainment on the downstream side of the protrusion. 2. An air casing (14) having a constant space (12) serving as a gas flow path between the frame tube (3) and the frame tube (3) and covering the same, the air casing (14) further comprising: A gas discharge port (16) for discharging the air sent through the gap into the frame tube is bored in the base portion, and the air discharged from the gas discharge port is used for combustion of fuel gas and The mixed promotion combustor according to claim 1, wherein the flame tube is cooled. 3. A cylindrical frame tube (3) having a combustion space inside which is closed at one end and opened at the other end, and a fixed space (12) serving as a gas flow path between the frame tube and the frame tube. Air casing (14) that covers the lever
And an air ejection pipe (4) connected to a side surface near one end of the frame tube, and a plurality of protrusions (8) protruding toward the inside of the frame tube are provided on an inner peripheral surface of the frame tube. A gas discharge port (1) for discharging the fuel gas sent through the gap into the frame tube at the root of each protrusion.
6) is perforated, air is ejected in the tangential direction of the frame tube from the air ejection tube, fuel gas is ejected into the frame tube from the gas emission port, and air and fuel gas are A mixing promotion combustor characterized in that a swirling flow (α) is generated along the inner peripheral surface, and a longitudinal vortex (β) is generated by entrainment on the downstream side of the protrusion to be agitated. 4. The projection (8) has a shape in which the height of the swirl flow (α) gradually increases gradually from the upstream side, and the height thereof rapidly decreases on the downstream side. The mixed promotion combustor according to any one of claims 1 to 3. 5. The projection (8) has a tetrahedral shape having a height that gradually increases from an upstream side to a downstream side and a width that gradually decreases, and has a shape in which a side wall thereof is a cliff.
The mixed promotion combustor according to any one of claims 1 to 3, wherein 6. The projection (8) is formed by bending a part of the frame tube (3) toward the inside of the frame tube, and the height of the swirling flow (α) gradually increases from the upstream side. The mixing promotion combustor according to claim 2 or 3, wherein the mixing promotion combustor has the following shape.