JP3375663B2 - Catalytic combustor - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to combustors. More specifically, the present invention relates to a combustor that uses both catalytic combustion and premixed combustion, and more particularly to a catalytic combustor suitable for use in a gas turbine.

[0002]

2. Description of the Related Art Conventionally, the use of a catalytic combustion method has been considered in order to suppress the NOx emission amount of a combustor for a gas turbine among combustors. However, this is difficult to put into practical use because the heat resistant temperature of the catalyst is low. Therefore, a catalytic combustor has been proposed in which catalytic combustion and gas phase combustion are combined so that the catalyst can be used at a temperature lower than the heat resistant temperature.

Conventionally, as such a combustor, Japanese Patent Laid-Open No.
No. 60-205128 is proposed. This combustion method is shown in FIG.
As shown in FIG. 4, the fuel supplied from the fuel nozzle 103 upstream of the catalyst 102 filled in the liner 101 of the combustor is catalytically burned by the catalyst 102, while the auxiliary fuel is supplied downstream of the catalyst 102 to generate a gas phase. I try to make it burn. The auxiliary fuel is supplied from a small hole 106 for fuel injection, which is drilled in the surface 105 of the blade of the swirler 104 installed downstream of the catalyst 102. Accordingly, the auxiliary fuel is injected into the catalytic combustion gas passing through the swirler 104, and is stirred with catalytic combustion gases swirling flow imparted by the Turkey to pass through the swirler 104. This allows
The catalyst temperature is kept below the heat resistant temperature of the catalyst and a combustion gas at a required temperature higher than that is obtained.

[0004]

However, the combustor shown in FIG. 6 is likely to cause diffusion combustion because the fuel is directly injected downstream of the catalyst outlet. Therefore, it is easily affected by the increase in NOx due to diffusion combustion, and it is difficult to reduce NOx.

Further, since a stirring means such as a swirler is provided on the downstream side of the catalyst, the high temperature catalyst combustion gas directly collides with the stirring means, and damage to the stirring means due to heat is unavoidable. Therefore, a complicated cooling structure is required in order to prevent burning of the stirring means.

Further, since the combustor shown in FIG. 6 is provided with the stirring means, the pressure loss of the combustor increases and the thermal efficiency decreases.

An object of the present invention is to provide a highly reliable catalytic combustor which can realize stable combustion with low NOx.

[0008]

In order to achieve the above object, the catalytic combustor of the present invention has a plurality of catalytic combustors and a premixing nozzle arranged substantially in the same plane in parallel on the circumference and in parallel with each other. A premixed combustion section for lean-mixed combustion of the catalyst combustion gas injected from the catalyst combustion section and the premixed gas injected from the premixing nozzle is disposed downstream of the premixed gas, and the premixed gas is directed to the flow of the catalyst combustion gas. And, at least the main flow of the premixing nozzle is provided in the premixing combustion section in a direction swirling in one direction with respect to the center axis of the premixing combustion section, and the main flow is provided in parallel with the catalytic combustion section and the premixing nozzle.
A non-flow path part where fuel and combustion air do not flow in the center of these
And a dead space downstream of it
A circulating flow is generated, a flame holding source is formed, and a lean premixed combustion is performed.
I am trying to make it. Here, the whole amount of the premixed gas may be injected in the same swirling direction, or a part thereof may be injected in a direction opposite to the main swirling direction.

Further, in the catalytic combustor of the present invention, the catalytic combustion parts and the premixing nozzles are arranged alternately in the circumferential direction.

Further, the catalytic combustor of the present invention, the range ratio and 1: 5 or less of the pair 30 or the cross-sectional area combined cross-sectional area and the catalytic combustion portion and the premixing nozzles of the non-channel portion Preferably. Further, it is preferable for stabilizing the premix combustion in the premix combustion section that the downstream end contour of the premix nozzle has a shape in which a stagnation flow or a circulation flow is likely to occur.

Further, in the catalytic combustor of the present invention, the flow rate ratio between the combustion gas ejected from the catalytic combustion section and the premixed gas ejected from the premixing nozzle is 3 in terms of volume in the standard state.
The ratio is preferably 7 or more and 9 to 1 or less.

[0012]

Therefore, the swirling flow is generated in the premix combustion section by the premix gas injected from the premix nozzle. In particular, a strong swirl flow is generated when all the premixed gas is injected in the same direction. On the other hand, when a part of the premixed gas is injected in the direction opposite to the main swirling direction, the swirling force is inferior, but the contact area with the catalytic combustion gas increases and the mixing property improves. This swirling flow collides with the catalytic combustion gas injected from the catalytic combustion unit and assists in mixing and diffusion with the premixed gas.
Moreover, since the non- flow passage is provided in the center and the swirling flow generates a negative pressure portion in the center to form a stagnation flow or a circulation flow, this becomes a spark and the catalyst combustion gas and the premixed gas in which combustion is unstable are formed. Achieve stable lean premixed combustion with. In particular, when the non-flow path portion is provided at the center or the downstream end profile of the premixing nozzle is rectangular or the like, generation of a stagnation flow or a circulation flow is promoted. Then, by the lean premixed combustion by mixing the combustion gas containing the unburned fuel from the catalytic combustion part injected into the premixed combustion part with the premixed gas, the combustor outlet temperature of the combustion gas becomes higher than the catalyst heat resistant temperature. To At this time,
Since the premixed gas is injected downstream of the catalyst outlet, there is no risk of diffusion combustion. Then, the ultra-high temperature region of 1700 ° C. or higher that generates thermal NOx does not occur, and the thermal NOx is suppressed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment in which the catalytic combustor of the present invention is applied to a gas turbine combustor. This catalytic combustion type gas turbine combustor includes a plurality of catalytic combustion units 1, 1,
1 and the premixing nozzles 2, 2 and 2 are arranged in parallel on the circumference in substantially the same plane, and the catalytic combustion unit 1 is provided downstream thereof.
The premixed combustion section 8 for performing lean premixed combustion of the catalyst combustion gas 11 injected from the premixed gas 12 and the premixed gas 12 injected from the premixed nozzle 2 is arranged, and the premixed gas 12 injected from the premixed nozzle 2 is , 3 for ejecting in the circumferential direction toward the catalytic combustion gas 11 are arranged in the radial direction. For example, in this combustor, as shown in FIG. 2, the catalyst combustion units 1 and the premixing nozzles 2 are alternately arranged in the circumferential direction, and the premixing gas injection port 3 is provided on one side of the premixing nozzle 2. There is. Further, a non-flow passage 4 through which fuel and combustion air do not flow is provided in the center of the catalytic combustion unit 1 and the premixing nozzle 2.

In general, a gas turbine combustor has a double cylinder structure including a casing (outer cylinder) 13 and a liner (inner cylinder) 14, and an air flow path 15 formed between the liner 14 and the casing 13. It is provided so that compressed air supplied from the gas turbine side is introduced into and is supplied to the premixing nozzle 2 and the catalytic combustion unit 1, respectively. A part of the compressed air introduced between the liner 14 and the casing 13 is part of the liner 1.
It is provided so as to be directly supplied to the premixing combustion section 8 inside the liner 14 as cooling air of No. 4 or as dilution air without passing through the catalyst combustion section 1 and the premixing nozzle 2.

As shown in FIG. 2, the premixing nozzles 2 are arranged in the circumferential direction so as to alternate with the catalytic combustion section 1 in a required number so as to cross the inside of the liner 11 in the radial direction, and the premixed gas is catalytically burned. The catalyst combustion gas 11 is injected toward the flow of the gas 11 and at least the main flow is swirled in one direction.
And the swirl flow 9 are formed while forcibly diffusing and mixing. The premixing nozzle 2 is provided so as to supply a premixed gas having a predetermined air ratio, for example, a concentration of the premixed gas that generates a large amount of NOx during the rated operation, to the premixed combustion section 8 including the liner 14. There is. The arrangement and shape of the injection port 3 of the premixing nozzle 2 are not particularly limited to those shown in FIG. 2 as long as the swirl flow 9 can be generated in the premixing combustion section 8. For example, as shown in FIG. 5 (A), the injection angle θ is reduced to reduce the turbulence of the catalytic combustion gas 11 and the mixture is provided so as to be mixed further downstream, or as shown in FIG. 5 (B). The premixed gas may be injected perpendicularly to the catalyst combustion gas 11 on one surface. Further, as shown in (C) or (D) of FIG. 5, injection ports 3 and 3'are provided on both sides of the premixing nozzle 2 so that injection is performed on both sides simultaneously, and the injection port 3'on one side thereof is The swirl flow 9 may be formed by reducing the number or the number of the injection ports 3 '. In this case, the premixed gas is injected only in the same direction as shown in FIGS. 2 or 5 (A) and (B).
Although the swirling force is inferior to that in the above case, the area of collision with the catalytic combustion gas 11 increases and mixing becomes easier.

Further, to the premixing nozzle 2, for example, an air introducing pipe 17 having a substantially rectangular shape that radially divides the inside of the liner 14 is connected to the upstream side, and the fuel nozzle 7 is arranged inside thereof. The air introduction pipe 17 divides the inside of the liner 14 into a space communicating with the catalytic combustion unit 1 (premixing unit 16) and a space communicating with the premixing nozzle 2. Therefore, the compressed air distributed according to the opening area ratio and the fuel ejected from the fuel nozzle 7 are provided so as to obtain a premixed gas having a predetermined concentration and supply the premixed gas to the premixing nozzle 2. Of course, the partition in the liner 14 is not limited to the method using the air introducing pipe 17 described above, and it is sufficient if the partition is substantially partitioned by, for example, a segment tube that constitutes the catalytic combustion unit 1. In the present embodiment, the entire area of the liner 14 upstream of the premixing nozzle 2 is radially partitioned by the air introducing pipe 17, and the catalyst combustion section 1 and the premixing nozzle 2 are separately controlled in concentration. However, the present invention is not particularly limited to this, and the inside of the liner 14 is divided at least on the downstream side of each of the fuel nozzles 6 and 7 to separate the catalyst combustion unit 1 and the premixing nozzle 2. It suffices that it is provided so as to supply the premixed gas whose concentration is controlled.

The premixed combustion section 8 is not particularly limited, but is made of, for example, ceramics or the like, and the liner 14 is used.
The inner peripheral wall surface is surrounded by a structure with little heat loss or a structure in which a large amount of cooling air is introduced. For example, by using a metal cylinder as a structural material and an inner wall made of ceramics, it is possible to obtain a stable combustion field having a more uniform temperature. In this case, the ceramic may be tile-like or fibrous. It is also possible to mold the entire liner with ceramics.

The catalytic combustion unit 1 is composed of, for example, a segment structure in which a casing is filled with a catalyst, and has a premixing unit 16 on the upstream side thereof. The premixing unit 16 is not particularly limited, but for example, a configuration may be adopted in which the fuel nozzle 6 is opened in a mere space into which compressed air is introduced to premix the compressed combustion air and the fuel. .
As the catalyst, it is possible to use an integrated catalyst having a large number of through holes, preferably a honeycomb-type, sponge-type or fiber-type integrated base material carrying an active ingredient on the surface,
Most preferably, a honeycomb type base material is used. further,
As a constituent material of the catalyst, it is preferable to use a base material such as a heat resistant alloy or ceramics and an active component such as a noble metal or a base metal oxide. Here, Inconel, Hastelloy as the heat-resistant alloy, cordierite, silicon nitride, silicon carbide as the ceramics, platinum as the noble metal, palladium, chromium oxide as the base metal oxide,
The use of cobalt oxide or the like is preferred.

The premixed gas usually has a temperature sufficient for catalytic combustion due to the heat of the compressed air itself, but when the temperature is insufficient, heat exchange with the turbine exhaust gas or introduction of another heat source is carried out. It is also possible to make up for it. For example, in the case of the present embodiment, the premixer 16 is equipped with the preburner 5 and is provided so as to obtain the premixed gas at a temperature at which catalytic combustion is possible. Also, this catalytic combustion unit 1
The fuel supplied to the premixing nozzle 2 and the fuel supplied to the premixing nozzle 2 do not have to be the same, and a completely different type of fuel may be adopted.

As a material for forming the premixing nozzle 2 and the catalytic combustion section 1, it is preferable to use a heat resistant material such as a heat resistant alloy or ceramics. Here, as the ceramics, for example, silicon carbide ceramics, silicon nitride ceramics, Sialon, etc. are preferably used.

In this combustor, the stability of the premixed combustion is maintained even by the catalytic combustion gas 11, so the flow rate ratio of the catalytic combustion gas 11 and the premixed gas 12 is 3 pairs in terms of volume in the standard state. It is preferable to set in the range of 7 or more and 9 to 1 or less. If the catalyst combustion gas 11 having a flow rate ratio of less than 3 to 7 is in a shortage state, the stability of combustion may be deteriorated and misfire may occur. On the contrary, when the flow ratio exceeds 9: 1 and the premixed gas 12 is insufficient, the swirling flow 9 is not generated, the mixed flame holding effect is reduced, and NOx is increased.

The ratio of the cross-sectional area of the non-flow passage portion 4 to the cross-sectional area of the catalyst combustion portion 1 and the premixing nozzle 2 excluding this is 1
It is preferable to set in the range of not less than 30 and not more than 1: 5. When this cross-sectional area ratio is less than 1:30, the formation of a stagnation flow or a circulation flow becomes insufficient. Further, if the cross-sectional area ratio exceeds 1: 5, the pressure loss increases due to the decrease in the flow passages.

For air and fuel, for example, the outlet temperature of the catalytic combustion section 1 at the rated load and the outlet gas temperature of the combustor are each kept at a predetermined temperature, and the catalytic combustion section 1 is not completely combusted in a fixed range (for example, 5 of fuel supplied to catalytic combustion section
It is achieved by controlling the flow rate and the flow velocity in accordance with the catalyst specifications so that an unburned content (about 50 Vol%) is supplied to the premix combustion section 8. As a result, it is possible to perform stable combustion in the premixed combustion unit 8 with very little NOx generation. For example, the first temperature sensor (not shown) in the catalytic combustion unit 1 controls the amount of fuel to the catalytic combustion unit 1 so that the temperature of the catalytic combustion unit 1 becomes equal to or lower than the catalyst heat resistant temperature (usually 800 to 1300 ° C.). Furthermore, the energy generated in the catalytic combustion unit 1 based on the air distribution to the catalytic combustion unit 1 and the temperature of the catalytic combustion unit 1 is the minimum energy required for maintaining the flame of the premixed combustion unit 8 (for example, heat generation of the entire combustor). (1/20 or more of the amount) and ensure that the combustor outlet gas temperature measured by a second temperature sensor (not shown) at the liner outlet reaches a predetermined temperature (usually 1000 to 1500 ° C.). The opening degree of each combustion air distribution valve and the fuel supply amount to the premixing nozzle 2 are controlled. Through the above series of operations, stable premixed combustion and protection of the catalyst layer can be achieved.

The gas turbine combustor of the present invention constructed as described above operates as follows.

[0026] First, after starting the air supply to the combustor from the compressor performs pre-combustion by supplying fuel to the Puribana 5, preheating the catalyst to the catalytic combustion enabling temperature by the combustion gases. Next, the fuel is supplied to the fuel nozzle 6 and mixed with the above-mentioned pre-combustion gas, and the mixed gas is supplied to the catalytic combustion unit 1 to perform catalytic combustion. On the other hand, fuel is supplied from the fuel nozzle 7 to the upstream of the premixing nozzle 2 and mixed with air, and is injected as premixed gas into the catalyst combustion gas from the catalyst combustion section 1 from the ejection port 3 of the premixing nozzle 2. As a result, a swirl flow 9 is generated in the premix combustion unit 8, the mixing of the catalyst combustion gas 11 and the premix gas 12 is promoted, and a stagnation flow or a circulation flow 10 is formed on the central axis of the premix combustion unit 8. Occur. Further, as shown in FIG. 3, when the downstream end profile of the premixing nozzle 2 is a shape in which a stagnation flow or a circulation flow is likely to occur, for example, a prismatic shape, the stagnation flow or the circulation flow 10 is also downstream thereof. Occurs, this serves as a flame holding source, which enables stable lean premixed combustion.

According to the combustor of the present invention,
By burning low-calorie gas such as LNG, LPG, coal gasification gas and other gas fuels and liquid fuel such as diesel oil and methanol, combustion gas of low NOx and high temperature can be obtained. That is, while maintaining the minimum amount of unburned fuel necessary for maintaining the flame of the premixed combustion section 8, only an amount that does not completely burn, for example, 10
Fuel and air sufficient to obtain a catalytic combustion gas of 00 ° C. or less are supplied to the catalytic combustion unit 1 to perform catalytic combustion, while the remaining fuel and air are supplied to the premixing nozzle 2 to generate a lean premixed gas. , It is injected in the circumferential direction so as to collide with the catalyst combustion gas 11 injected from the catalyst combustion unit 1 to form a swirl flow in which the catalyst combustion gas 11 and the premixed gas 12 are mixed to form a stable lean pre-gas. Perform mixed combustion. Then, while suppressing the generation of NOx, a combustion gas having a combustor outlet temperature of, for example, 1300 ° C. necessary for the gas turbine combustor is obtained.

It should be noted that the above-mentioned embodiment is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the gas turbine catalytic combustor has been mainly described, but the present invention is not particularly limited to this and can be applied to a normal combustor.

[0029]

As is apparent from the above description, in the catalytic combustor of the present invention, a plurality of catalytic combustors and premixing nozzles are arranged in parallel on the circumference in substantially the same plane, and the downstream of them. Is provided with a premixed combustion section for performing lean premixed combustion of the catalyst combustion gas injected from the catalyst combustion section and the premixed gas injected from the premixing nozzle, and the premixed gas is directed toward the flow of the catalyst combustion gas and at least An injection port of a premixing nozzle whose main flow is injected in a direction swirling in one direction with respect to the central axis of the premixing combustion part in the premixing combustion part is provided , and the non-flow path part is provided at the center. Therefore, the swirling flow is generated in the premixing combustion part by the premixing gas injected from the premixing nozzle, collides with the catalytic combustion gas and assists the mixing and diffusion with the premixing gas, and the stagnation flow or the circulating flow is formed in the center of the swirling flow. To form Les was the spark to enable stable lean premixed combustion of the catalytic combustion gas and the premixed gas.

Further, according to the combustor of the present invention, a stagnation flow or a circulation flow which is a flame holding source can be generated in the premixed combustion section, so that the lean premixed combustion which tends to be unstable can be stabilized. In particular, in the present invention, when the non-flow passage portion is provided at the center or the downstream end contour shape of the premixing nozzle is formed into a shape in which a stagnation flow or a circulation flow is easily generated, the generation of the stagnation flow or the circulation flow that is a fire source is promoted. This enables more stable lean premixed combustion. Further, when a part of the premixed gas is injected in the direction opposite to the main swirling direction, the mixing of the premixed gas and the catalytic combustion gas is further promoted, and local high temperature combustion can be prevented.

Moreover, according to the present invention, since it is not necessary to install a stirring means downstream of the catalyst, it is not necessary to take measures against damage to the stirring means due to heat, and the installation of the stirring means increases the combustor pressure loss. Can be avoided. Further, according to the present invention, since the mixing of the catalytic combustion gas and the premixed gas is promoted, a local high temperature region is not generated, NOx generation can be suppressed to an extremely low level, and the combustor outlet gas temperature uniformity can be improved. It is possible to prevent damage to the turbine blades installed downstream thereof.

[Brief description of drawings]

FIG. 1 is a principle diagram of a catalytic combustor of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

5 (A) to 5 (D) are an enlarged longitudinal cross-sectional view of an essential part showing an example of a premixing nozzle and a front view thereof.

6A and 6B are views showing an example of a conventional combustor for a catalytic combustion type gas turbine, in which FIG. 6A is a schematic structural view and FIG. 6B is a perspective view showing swirler blades.

[Explanation of symbols]

1 Catalytic combustion part 2 premix nozzle 3 Premixed gas injection port 4 non-flow path 5 Preburner 6 Fuel nozzle 7 Fuel nozzle 8 Premix combustion section 9 swirling flow 10 stagnation flow or circulation flow

Front Page Continuation (72) Inventor Junji Hirano 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. Kansai Electric Power Co., Inc. (72) Inventor Shinji Watanabe 3-3-22 Nakanoshima, Kita-ku, Osaka-shi, Osaka Kansai Electric Power Co., Inc. (56) Reference JP-A-2-259331 (JP, A) JP-A-4 -15410 (JP, A) JP-A-4-15411 (JP, A) JP-A 56-117023 (JP, A) JP-A 59-107119 (JP, A) JP-A 61-276627 (JP, A) ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F23R 3/00-7/00

Claims (7)

(57) [Claims] 1. A plurality of catalytic combustion units and a premixing nozzle are arranged in parallel on the circumference in substantially the same plane, and the catalytic combustion gas injected from the catalytic combustion unit and the premixing nozzle are arranged downstream of them. A premixed combustion section is provided for performing lean premixed combustion with the injected premixed gas, and the premixed gas is directed to the flow of the catalytic combustion gas, and at least the main flow thereof is in the premixed combustion section. Rutotomoni the catalytic combustion portion relative to the center axis is injected in a direction to pivot the <br/> one direction is provided an injection port of the premixing nozzles and premixing nozzles of
Fuel and combustion air do not flow to these centers in parallel with
A non-flow path, and a dead space downstream
A stagnation flow or circulating flow is generated to form a flame holding source and dilute
A catalytic combustor characterized by premixed combustion . 2. The catalytic combustor according to claim 1, wherein the entire amount of the premixed gas injected from the premixing nozzle is injected in a direction swirling in one direction. 3. The catalytic combustor according to claim 1, wherein a part of the premixed gas injected from the premixing nozzle is also injected in a direction opposite to the main swirling direction. 4. The catalytic combustor according to claim 1, wherein the catalytic combustion section and the premixing nozzle are alternately arranged in the circumferential direction. 5. The cross-sectional area of the non-flow passage portion, the catalytic combustion portion, and the
The ratio to the cross-sectional area of the mixing nozzles is 1:30 or more, and
The catalytic combustor according to any one of claims 1 to 4, wherein the ratio is 1 to 5 or less . 6. An end profile on the downstream side of the premixing nozzle
The shape should be such that a stagnation flow or a circulating flow is likely to occur.
The catalytic combustor according to any one of claims 1 to 5, which is characterized. 7. Combustion gas ejected from the catalytic combustion unit
And the flow rate ratio of the premixed gas ejected from the premix nozzle is
Claims 1, characterized in Oh <br/> Rukoto in 3: 7 or more and 9: 1 or less in terms of volume under standard conditions the catalytic combustor according to any one of 6. Catalytic combustor.