JPH0316567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas turbine combustor, and particularly to a gas turbine combustion system using a catalytic combustion method that uses a catalyst to reduce the production of nitrogen oxides generated in the combustor. Concerning vessels.

[Technical background of the invention and its problems]

There are strict environmental regulations regarding nitrogen oxides (hereinafter referred to as NOx) emitted from gas turbine plants and combined plants, and various countermeasures such as water injection methods and De-NOx treatment have been adopted, but none of them are suitable for plants. This is fraught with problems such as decreased efficiency and increased equipment costs. Catalytic combustion is a method that has attracted attention in recent years as a measure to reduce NOx. This attempts to complete combustion at a low temperature by using a catalyst installed in the combustor.

That is, FIG. 4 is a diagram showing a conventional catalytic combustor, in which compressed air a exits a compressor (not shown).
is the annular gap formed between the outer cylinder 1 and the inner cylinder 2.
It passes through the section 3 and reaches the head of the inner cylinder while cooling the wall surface of the inner cylinder 2, where it is reversed and made into a swirling flow by the swirler 4, and is supplied into the combustion chamber within the inner cylinder 2. On the other hand, the fuel b is injected into the inner cylinder 2 through the fuel injection valve 5, and mixed well with the air by the swirling flow of air by the swirler 4, becoming a homogenized air-fuel mixture in the premixing area 6, and When the gas passes through the catalyst 7 provided in the cylinder 2, catalytic combustion occurs due to a catalytic reaction, and the gas is turned into high-temperature gas and sent to the turbine side.

In this way, in catalytic combustion, there is no need to dilute high-temperature gas as in conventional gas turbine combustors, that is, there is no high-temperature section, so low-temperature combustion is possible, and NOx emissions can be kept to a minimum.

However, in high-load combustors such as gas turbine combustors, the average flow velocity inside the combustor is high and the contact time of the catalyst is short, so the conventional catalytic combustion method, which is dominated by diffusion control, cannot There were problems such as difficulty in maintaining high efficiency. In addition, under high-load combustion conditions, the flow velocity increases, which increases the pressure drop before and after the catalyst, resulting in an increase in combustor pressure drop, which negates the improvement in plant efficiency caused by stopping steam injection, etc. There are some inconveniences. Furthermore, if the combustion method and combustion conditions are set to reduce the heat load on the catalyst in order to increase the durability of the catalyst, the combustion efficiency will decrease, and due to the non-uniformity of the premixed gas flowing into the catalyst, partial heating of the catalyst (hot spots) will occur. There are problems such as combustion accidents occurring due to etc.

[Purpose of the invention]

In view of these points, the present invention provides a catalytic combustor that uses catalytic combustion to reduce NOx, which is extremely stable and has high combustion efficiency even under high-load combustion conditions with a large average flow velocity. The aim is to obtain a low NOx gas turbine combustor with small pressure drop.

[Summary of the invention]

The present invention provides a gas turbine combustor in which an inner cylinder constituting a combustion chamber is arranged concentrically within an outer cylinder, and compressed air is fed through an annular space between the two cylinders. A premixing duct is arranged concentrically on the outer periphery of the pilot fuel nozzle and swirler provided at the center of one end, and a catalyst body is provided at the tip of the premixing duct on the inner cylinder side. a plurality of first fuel nozzles that are parallel to each other with respect to the axis of the inner cylinder, and further a catalyst body forming a part of the inner cylinder wall on the inner cylinder peripheral wall immediately downstream of the catalyst body of the premixing duct. are arranged in the circumferential direction, and a number of second fuel nozzles oriented in the radial direction are provided in the premixing duct radially outward from the catalyst body.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 10 denotes a cylindrical outer cylinder in the combustor, and the outer cylinder 10
Inside is an inner cylinder 11 that forms a combustion chamber concentrically with this.
is installed. A pilot fuel nozzle 12 is provided on the central axis at the center of one end of the inner cylinder 11, and a swirler 13 is provided on the outer periphery of the tip of the pilot fuel nozzle 12. A flame stabilizer 14 having a truncated conical cross section that expands toward the inside of the inner cylinder 11 is disposed at the outer peripheral tip of the swirler 13.
On the outer periphery of the flame stabilizer 14, a retaining ring 15 consisting of a double inner and outer cylinder concentric with the axis of the pilot fuel nozzle 12 is provided. The retaining ring 15 forms an annular premixing duct 16 with its inner and outer double cylindrical bodies, and a catalyst body 17 is provided on the end surface of the premixing duct 16 on the side of the inner cylinder 11 over its entire circumference. The catalyst body 17 forms a part of one end surface of the inner cylinder 11. Further, within the premixing duct 16, a large number of first fuel nozzles 18 are provided in the circumferential direction, which are oriented in the axial direction of the inner cylinder 11.

Further, two donut-shaped retaining rings 19, 19 are provided on the outer periphery of the inner cylinder 11 near the one end, and are spaced apart from each other in the axial direction. A cylindrical catalyst body 20 is mounted and held so as to form a part of the inner surface, and a radially outer part of the catalyst body 20 includes:
In the premixing duct formed by the retaining rings 19, 19, a number of second fuel nozzles 21 are arranged in the radial direction and open toward the central axis of the inner cylinder 11 in the circumferential direction and the axial direction. They are arranged and mounted at predetermined intervals.

Further downstream of the catalyst body 20, a plurality of premixing pipes 22 are installed in the inner cylinder 11 at equal intervals in the circumferential direction and in the radial direction, and are opened into the inner cylinder 11. A third fuel nozzle 23 is provided inside each pipe 22 near its outer end. A plurality of dilution holes 24 are bored in the inner cylinder 11 on the downstream side of the premixing pipe 22. On the other hand, an igniter 2 is placed between the catalyst 17 held by the retaining ring 15 and the retaining ring 19.
5 is provided.

Incidentally, the end plate 10a of the outer cylinder 10 is provided with fuel headers 26, 27, and 28, and the fuel header 26 is connected to the pilot fuel nozzle 12 and, on the other hand, to the first fuel valve 29. . The fuel header 27 is secondly connected to a fuel valve 30 and is also connected via a pipe 31 to a large number of first fuel nozzles 18 and second fuel nozzles 21 so as to uniformly distribute and supply fuel. There is. Furthermore, the fuel header 28 is connected to a third fuel valve 32 and is also connected via a pipe 33 to the plurality of third fuel nozzles 23 so as to uniformly distribute and supply fuel.

Therefore, high-pressure air a supplied from an air compressor (not shown) passes through the annular passage 34 formed by the inner cylinder 11 and the outer cylinder 10 into the outer cylinder 10.
0 end, where it is given a swirling motion by the swirler 13 and flows into the pilot fuel nozzle 1.
It diffuses and mixes with the fuel ejected from 2 and flows into the inner cylinder 11 to form a flame-holding region, thereby forming a pilot flame for combustion of the premixed gas.

Further, a part of the high pressure air a is supplied to the retaining ring 15
The fuel also flows into the premix duct 16 formed by the above, where it becomes a premix gas with the fuel jetted out from a number of first fuel nozzles 18 attached to that part, and is then partially oxidized and burned in the catalyst body 17. ,
The combustion gas becomes jet _a1 and flows into the inner cylinder 11 in a direction substantially parallel to the axis. Similarly, a portion of the high-pressure air also flows between the retaining rings 19 and 19, where it is premixed with fuel ejected from a number of second fuel nozzles 21 to become a premixed gas, and is further partially oxidized in the catalyst body 20. It burns, becomes a combustion gas jet _a2 , and flows into the inner cylinder 11 from its outer periphery in a substantially radial direction.

Furthermore, another part of the high pressure air a flows into the premix pipe 22 as air a ₃ for premixing with the fuel jetted from the third fuel nozzle 23 attached to the premix pipe 22, and becomes a premix jet. It flows into the inner cylinder 11 as _a4 . Further, another part of the high pressure air a flows into the inner cylinder 11 from the dilution hole 24 as an air jet _a5 .

Therefore, when fuel is supplied to the pilot fuel nozzle 12 through the first fuel valve 29 and ignition energy is applied by the igniter 25, a flame is formed in a flame holding region. Then, the fuel supplied from the first fuel valve 29 is gradually increased, and when the gas turbine becomes independent and reaches the rated rotational speed, the second and third fuel valves
Supply of fuel is started from the fuel valves 30 and 32 of.

On the other hand, high-pressure air is produced by adiabatic compression of an air compressor.
The temperature is about 300°C to 500°C, and the premixed gas, etc. in the premixing duct 16 formed by the retaining ring 15 and the premixing duct formed between the retaining rings 19 are in contact with each other. While passing through the media 17 and 20, it is partially oxidized, becomes combustion gas jets a ₁ and a ₂ together with unburned fuel, flows into the inner cylinder 11, and comes into contact with the high-temperature gas of the pilot flame to reduce the oxygen concentration and the fuel. Combustion continues under lean conditions and complete combustion occurs without producing NOx. Furthermore, the premixed jet a ₄ that flows into the inner cylinder 11 from the premix pipe 22 similarly contacts the high temperature gas flowing inside the inner cylinder 11 and continues combustion under low oxygen and fuel lean conditions, suppressing NOx generation. and completely burns.

Here, the premix duct 16 and the retaining ring 1
9, the equivalence ratio of the fuel in the premix pipe 22 is 0.5 or less, and the equivalence ratio in the premix pipe 22 is 0.6 or less.
Determine fuel and air distribution. In addition, the value of the pressure difference between the inside and outside of the inner cylinder 11 or the pressure drop of the combustor is
The flow velocity of the premixed gas flowing in the upstream portions of 7 and 20 and in the premixing pipe 22 is set to be higher than the combustion velocity in order to prevent flashback. Furthermore, the distribution of each fuel supplied to each fuel nozzle, the premixed gas equivalence ratio, etc. can be changed depending on the type of fuel.

Thus, by having a large number of fuel nozzles oriented parallel to the axis of the inner cylinder and radially inward, the non-uniformity of the premixing of fuel and air can be corrected. Can be done. Furthermore, by making the catalyst structure into a concentric cylindrical shape that forms part of the inner cylinder wall using the retaining ring 19, the axial length can be freely selected.
It is possible to increase the capacity of the premixed gas or the outflow surface area of the fuel gas jet, and it is possible to suppress the combustor pressure drop to the same level as the conventional type (3 to 4%) without making the inner cylinder diameter abnormally large. becomes.

In the above embodiment, the catalyst body 20 was formed into a cylindrical shape, but it may also have a shape in which a plurality of catalyst bodies are arranged in the circumferential direction as shown in FIG. A similar effect can be achieved by arranging a plurality of catalyst bodies in a polygonal shape as shown in FIG. 3b.

〔Effect of the invention〕

As explained above, in the present invention, a pilot fuel nozzle and a swirler are provided at one end of the inner cylinder, and the combustion gas jet that has passed through the catalyst body flows from the outer circumference of the pilot fuel nozzle into the inner cylinder parallel to its axis. At the same time, since the combustion gas jets that have passed through the catalyst in the downstream region flow into the inner cylinder in a radial direction, the combustion gas jets collide and mix with each other, resulting in uniform premixing of fuel and air, as well as the pilot flame. Collision mixing can be performed, reducing the amount of combustion (heat load) on the catalyst, and improving the durability of the catalyst. Furthermore, since the inner cylinder wall in the high temperature region can be formed by the catalyst body, the amount of cooling air for cooling the inner cylinder can be reduced, and the surface area of the inner cylinder wall in the high temperature region can be reduced by the catalyst body. This can be changed by selecting the axial length, and the pressure drop across the combustor can be selected to an ideal value. Further, as mentioned above, by uniformly premixing the fuel and air, there is an effect that burnout accidents due to hot spots on the catalyst do not occur.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the gas turbine combustor of the present invention, FIG. 2 is a view taken from FIG. FIG. 4 is a sectional view showing an example of a conventional catalytic combustor. 10... Outer cylinder, 11... Inner cylinder, 12... Pilot fuel nozzle, 13... Swirler, 15, 19
...Retaining ring, 17, 20...Catalyst body, 18...
...first fuel nozzle, 21 ... second fuel nozzle, 22 ... premix pipe, 23 ... third fuel nozzle, 24 ... dilution hole.

Claims (1)

[Scope of Claims] 1. A gas turbine combustor in which an inner cylinder constituting a combustion chamber is arranged concentrically within an outer cylinder, and compressed air is supplied through an annular gap between the two cylinders. A premixing duct is arranged concentrically on the outer periphery of the pilot fuel nozzle and swirler provided at the center of one end of the cylinder, and a catalyst body is provided at the tip of the premixing duct on the inner cylinder side. A large number of first fuel nozzles are provided on the end side parallel to each other with respect to the axis of the inner cylinder, and further, a part of the inner cylinder wall is formed on the peripheral wall of the inner cylinder immediately downstream of the catalyst body of the premixing duct. A gas turbine characterized in that a catalyst body is disposed in the circumferential direction and a number of radially oriented second fuel nozzles are provided in a premixing duct radially outward from the catalyst body. combustor. 2. The gas turbine combustor according to claim 1, wherein the catalyst body forming a part of the inner cylinder wall is formed in a cylindrical shape. 3. A patent characterized in that the catalyst body forming a part of the inner cylinder wall is provided at the inner end of a plurality of premixing ducts provided at equal intervals in the circumferential direction on the inner cylinder peripheral wall. A gas turbine combustor according to claim 1. 4. The gas turbine according to claim 1, wherein the catalyst body forming a part of the inner cylinder wall is provided at the inner end of the premixing duct arranged in a polygonal shape. combustor.