JP2005257117A - Combustion air variable mechanism for gas turbine combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote the reduction of cost and NOx by mounting a bypass valve particularly in an outer cylinder of a compact gas turbine. <P>SOLUTION: This combustion air variable mechanism of the gas turbine combustor 1 comprising the outer cylinder 2 and an inner cylinder 5 having a bypass hole 8, further comprises an air introducing part 21 mounted between the outer cylinder and the inner cylinder extended to an outer side from the bypass hole of the inner cylinder, introducing the air discharged from a compressor and flowing between the outer cylinder and the inner cylinder, into the inner cylinder, and provided with a valve seat 24 on an outer end part, a valve element 31 kept into contact with the valve seat of the air introducing part for closing the valve, and forbidding the flowing of the air discharged from the compressor, into the cylinder, and a driving part 41 for opening and closing the valve element from the outside of the outer cylinder. The air introducing part is composed of a movable part flexibly moved in the radial or axial direction of the inner cylinder, and detachably fitted to the bypass hole of the inner cylinder at its inner end part, and the air introducing part and the valve element are detachably mounted on the outer cylinder from the outside of the outer cylinder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a combustion air variable mechanism of a gas turbine combustor that is particularly suitable for use in a small gas turbine.

Reducing the NO _X emissions increase rapidly due to the higher output of the gas turbine is a critical problem in environmental gas turbine. In particular, in the case of a small gas turbine, it is often difficult to provide a denitration device because of operating costs, installation space, and the like. Therefore, in the small gas turbine, it is necessary to reduce the NO _X emissions by improving combustion.

Low NO _X of the gas turbine combustor has been carried out mainly by water injection or steam injection so far. However, these methods, because of the difficulties such as the maintenance of reduction in the thermal efficiency and equipment problems, there is an urgent need development of low NO _X combustor dry Without this water injection or steam injection. As one method for this, in a large gas turbine, an internal combustion air adjustment mechanism with a transition piece of the outer tube, the premixed combustion by the combustion air variable mechanism with a combustor, the low NO _X reduction There is something to plan (for example, see Non-Patent Document 1).

In a large gas turbine based on the premixed combustion method, for example, as shown in FIG. 7, the compressor discharge air flows into the combustor 100 and is mixed with fuel and combusted. The hot gas after combustion is guided to the turbine 102 through the tail cylinder 101. The variable combustion air mechanism 103 is fully opened at a low load so that an appropriate air-fuel ratio can be secured in the combustor, and bypasses a part of the compressor discharge air and directly guides it into the transition piece 101. As the load increases, the fuel injection amount increases, and the bypass valve 104 of the combustion air variable mechanism 103 is sequentially closed, so that the throttle valve is considerably throttled near the rated load operation. The bypass valve 104 is formed of, for example, a butterfly valve disposed inside the outer cylinder 105.
Shigemi Sashiro, Kuniaki Aoyama, “Premixed Combustor”, Journal of the Gas Turbine Society of Japan (Vol. 16, No. 64), Japan Gas Turbine Society, March 10, 1989, p. 26 (Fig. 2)

Thus, in a conventional large gas turbine, for example, a tail cylinder with a combustion air variable mechanism using a bypass valve composed of a butterfly valve is provided inside the outer cylinder, and premixed combustion by a combustor with a combustion air variable mechanism is provided. by, we went the low-NO _X reduction. However, in a small gas turbine, it is necessary to downsize the entire gas turbine including the outer cylinder because of the installation space and the like, and a bypass valve composed of a butterfly valve, for example, having the same structure as the large gas turbine inside the outer cylinder. It is difficult to provide

  On the other hand, when the variable combustion air mechanism is disposed outside the outer cylinder, there is a problem that the configuration of the variable combustion air mechanism is complicated and the cost is increased.

The present invention has been made to solve such a problem. By downsizing, it is possible to dispose a bypass valve particularly in the outer cylinder of a small gas turbine, thereby reducing the cost and reducing the cost. It is an object of the present invention to provide a combustion air variable mechanism of a gas turbine combustor that can promote NO _x conversion.

  In order to solve the above-mentioned problem, the means employed by the present invention is a combustion air variable mechanism of a gas turbine combustor provided with an outer cylinder and an inner cylinder having a bypass hole, and the combustion air variable mechanism includes: Compressor discharge air that is formed in a cylindrical shape and is disposed between the outer cylinder and the inner cylinder, extends outward from the bypass hole of the inner cylinder, and flows between the outer cylinder and the inner cylinder is introduced into the inner cylinder. And an air introduction portion having a valve seat formed at the outer end, a valve body that abuts against the valve seat of the air introduction portion and closes the valve body to prohibit the flow of compressor discharge air into the inner cylinder, and a valve body. And a drive unit that opens and closes from the outside of the outer cylinder.

  Therefore, by operating the drive unit, the valve body can be opened and closed with respect to the valve seat of the air introduction unit, whereby the compressor discharge air flows into the inner cylinder of the gas turbine combustor or the inflow thereof. Therefore, the air-fuel ratio in the gas turbine combustor can be appropriately changed according to the output of the gas turbine. Further, the combustion air variable mechanism is configured by including an air introduction unit, a valve body, and a drive unit, and can be downsized. In particular, the air introduction unit and the valve body that constitute the bypass valve are connected to a small gas turbine. It becomes possible to arrange | position in the outer cylinder.

  The air introduction part desirably has a movable part that moves flexibly in the radial direction and / or the axial direction of the inner cylinder. There is a dimensional difference between the outer cylinder and the inner cylinder of the gas turbine combustor due to thermal expansion, vibration, and the like. By having the movable part that moves flexibly in the radial direction and / or the axial direction of the inner cylinder, the air introduction part can absorb this dimensional difference.

  As for an air introduction part, it is desirable for the inner end part to fit in the bypass hole of an inner cylinder so that insertion or removal is possible. By fitting the air introduction part into the bypass hole of the inner cylinder so as to be detachable, the air introduction part can be easily attached and detached, and the maintainability of the air introduction part and the inner cylinder is improved.

  It is desirable that the valve body and the air introduction part are fixed to the outer cylinder so as to be detachable from the outside of the outer cylinder. By fixing the valve body and the air introduction part to the outer cylinder detachably from the outside of the outer cylinder, the valve body and the air introduction part can be attached and detached without disassembling the gas turbine body. In addition, the maintainability of the valve body and the air introduction part is improved.

The bypass hole and the combustion air variable mechanism are composed of a plurality, and the combustion air variable mechanism desirably closes the valve bodies sequentially from the low output to the high output of the gas turbine. A plurality of combustion air variable mechanism, by sequentially closing the valve body subjected at high power from the time of low power output of the gas turbine, the entire power range of the gas turbine, it is possible to enhance the low NO _X reduction.

  The drive unit is preferably opened and closed by an air cylinder fixed to the outside of the outer cylinder and operated by compressor discharge air, and a controller for controlling the operation of the air cylinder. By configuring the drive unit in this manner, the opening and closing of the valve body can be automatically controlled. In particular, since the air cylinder is operated by compressor discharge air, it is not necessary to separately provide a cylinder operating source.

  The controller desirably opens and closes the valve body based on any one or more of the power generation output of the gas turbine, the intake air temperature, the compressor outlet air pressure or shaft rotational speed, and the combustor inlet air temperature. Thus, by controlling the opening and closing of the valve body based on the power generation output of the gas turbine, the intake air temperature, the compressor outlet air pressure or shaft rotation speed, the combustor inlet air temperature, in any operating state of the gas turbine, Ideal open / close control can be performed.

  For example, the combustor is a single cylinder type. The combustion air variable mechanism of the gas turbine combustor of the present invention can be implemented in all gas turbines from large to small, but is particularly suitable for use in a small gas turbine having a single cylinder combustor.

As described above in detail, the variable combustion air mechanism for a gas turbine combustor according to the present invention is a variable combustion air mechanism for a gas turbine combustor including an outer cylinder and an inner cylinder having a bypass hole. The variable air mechanism is formed in a cylindrical shape and is disposed between the outer cylinder and the inner cylinder, extends outward from the bypass hole of the inner cylinder and flows into the compressor discharge air flowing between the outer cylinder and the inner cylinder. An air introduction portion that is introduced into the cylinder and has a valve seat formed at the outer end portion thereof, and a valve body that abuts the valve seat of the air introduction portion and closes the valve body to inhibit the discharge of the compressor discharge air into the inner cylinder And a drive part that opens and closes the valve body from the outside of the outer cylinder, the combustion air variable mechanism can be reduced in size, and in particular, the bypass valve can be disposed in the outer cylinder of the small gas turbine, Yu that thereby with cost reduction, it is possible to enhance the low NO _X reduction It was an effect.

  A best mode for carrying out a combustion air variable mechanism of a gas turbine combustor according to the present invention will be described in detail with reference to FIGS.

  1 is a cross-sectional view showing a combustion air variable mechanism of a gas turbine combustor according to the present invention, FIG. 2 is a cross-sectional view showing the combustion air variable mechanism of FIG. 1, and FIG. 3 is a plan view showing the valve seat of FIG. 4 is a cross-sectional view showing an operating state different from FIG. 2, FIGS. 5A to 5D are schematic views showing the open / close state of the valve body, and FIG. 6 is a combustion air variable mechanism of FIG. It is a graph which shows the combustion control using.

  As shown in FIG. 1, a combustor 1 of a gas turbine is a single cylinder type, and includes an outer cylinder 2 as a combustor case and an inner cylinder 5 that performs combustion inside. The inner cylinder 5 further includes a main combustor 6 and a tail cylinder 7 and is fixed to the outer cylinder 2 by a plurality of fixing pins 10. The main combustor 6 is provided with a fuel injection nozzle 11 and a spark plug 12. Further, four bypass holes 8 are formed in the tail cylinder 7 at equal intervals on the circumference. The four bypass holes 8 are each provided with a combustion air variable mechanism 20 described later. A passage 3 between the outer cylinder 2 and the inner cylinder 5 in the lower part of the drawing communicates with a compressor outlet (not shown), and compressor discharge air flows into the combustor 1 through the passage 3. On the other hand, the outlet 9 of the transition piece 7 communicates with a turbine inlet (not shown), and the combustion gas is guided to the turbine.

  As shown in FIG. 2, each combustion air variable mechanism 20 includes an air introduction portion 21, a valve body 31, and a drive portion 41, and the air introduction portion 21 and the valve body 31 that constitute a bypass valve include the outer cylinder 2. Are disposed in the four cylindrical combustion air variable mechanism accommodating portions 51 projecting radially outward from the cylinders. This combustion air variable mechanism accommodating part 51 also forms a part of the outer cylinder 2.

  As shown in FIGS. 2 and 3, the support plate 22 of the air introduction portion 21 has a short cylindrical bellows member support portion 23 at the center thereof, and a valve seat 24 at the left end portion (outer end portion) shown in the drawing. Is formed. Three air insertion holes 25 are formed around the bellows member support portion 23. As shown in FIG. 2, a cylindrical bellows member (movable portion) 26 is fixed to the bellows member support portion 23 of the air introduction portion 21, and a tip end is shown at the right end portion (inner end portion) of the bellows member 26. Is formed in a cylindrical shape or a tapered cylindrical shape, and a fitting portion 27 that can be detachably fitted into the bypass hole 8 of the tail tube 7 is fixed.

  Thus, the air introduction part 21 extends radially outward from the bypass hole 8 of the tail cylinder 7, and discharges the compressor discharge air flowing between the outer cylinder 2 and the inner cylinder 5 into the bellows member 26 and the bypass hole. 8 is introduced into the transition piece 7. Further, since the bellows member 26 can move flexibly not only in the radial direction of the tail cylinder 7 but also in the axial direction of the tail cylinder 7, the outer cylinder 2 and the inner cylinder of the combustor 1 are caused by thermal expansion, vibration, or the like. Even if a dimensional difference occurs with respect to 5, the fitting portion 27 is moved in an elastic manner in the radial direction of the inner cylinder 5 and flexibly moved in the axial direction of the inner cylinder 5 to absorb this dimensional difference. can do.

  The valve body 31 is fixed to the tip of a valve shaft (drive unit) 42, and the valve shaft 42 penetrates the lid member 52 airtightly through a seal 53 and is fixed to the outside of the outer cylinder 2 (drive). Part) 43. For this reason, the valve shaft 42 reciprocates due to the operation of the air cylinder 43, and the valve body 31 is brought into contact with the valve seat 24 of the air introduction portion 21 to close the valve, whereby the compressor discharge air enters the tail cylinder 7. Inflow can be prohibited. The air cylinder 43 is operated by the compressor discharge air of the gas turbine, and its operation is automatically controlled by a controller (not shown). The controller receives the power generation output of the gas turbine, the intake air temperature, the compressor outlet air pressure or shaft rotation speed, and the combustor inlet air temperature signals. These power generation output, the intake air temperature, and the compressor outlet air The operation of the air cylinder 43 is controlled based on the pressure or shaft rotational speed and the combustor inlet air temperature.

  This is because the flow rate of the fuel changes depending on the power generation output, and therefore it is necessary to open and close the valve body 31 using the power generation output as a parameter to keep the operating air-fuel ratio within a certain range. Further, since the intake air flow rate changes depending on the intake air temperature of the gas turbine, it is necessary to keep the operating air-fuel ratio within a certain range using the intake air temperature as a parameter. The intake air temperature greatly affects the amount of moisture in the air, and the combustion state changes depending on the amount of moisture in the air. In order to cope with this change in the combustion state, it is necessary to adjust the operating air-fuel ratio by opening and closing the valve body 31 using the intake air temperature as a parameter.

On the other hand, may reduce the emissions NO _X in startup, it is possible to the the fuel at startup and fuel at the time of continuous operation different. In such a case, it is necessary to detect the start or the continuous operation using the compressor outlet air pressure or the shaft rotational speed as a parameter. In a regeneration cycle system or the like, the combustor inlet air temperature varies depending on the operation state of the regeneration cycle. In order to compensate for the influence of the change in the combustor inlet air temperature, it is necessary to adjust the operating air-fuel ratio by opening and closing the valve body 31 using the combustor inlet air temperature as a parameter.

  The lid member 52 and the support plate 22 are fixed to the combustion air variable mechanism housing portion 51 by bolts 54 and nuts 55. Moreover, the fitting part 27 of the bellows member 26 of the air introduction part 21 is detachably fitted into the bypass hole 8 of the tail cylinder 7 as described above. Therefore, the valve body 31 and the air introduction part 21 are detachable from the outside with respect to the outer cylinder 2, and can be removed and attached without disassembling the gas turbine main body. Serviceability is very good.

  Next, the operation when the combustion air variable mechanism of the gas turbine combustor is controlled by, for example, the power generation output of the gas turbine will be described.

  As shown in FIG. 5A, the controller opens all four combustion air variable mechanisms 20 when the gas turbine is started and when the output is low. As shown in FIG. 2, the compressor discharge air flowing through the passage 3 between the outer cylinder 2 and the inner cylinder 5 and flowing between the combustion air variable mechanism housing portion 51 and the bellows member 26 of the air introduction portion 21 is Then, the air flows into the bellows member 26 through the three air insertion holes 25 of the support plate 22 of the air introduction portion 21. The compressor discharge air flowing into the bellows member 26 is further introduced into the tail cylinder 7 through the bypass hole 8.

6, equipped with a combustion air adjustment mechanism 20 described above is a graph showing a combustion control in 1,100PS class simple open-cycle, single-shaft small gas turbine as an example, in the power generation output 0%, NO _X emissions Is about 50 ppm. NO _X emissions increases with increasing power output is about 65ppm in power output of about 25%.

When the power generation output reaches 25%, the controller closes one combustion air variable mechanism 20 as shown in FIG. Specifically, as shown in FIG. 4, the controller activates the air cylinder 43 to bring the valve body 31 into contact with the valve seat 24 of the air introduction unit 21 to close the valve. Thereby, the compressor discharge air that has flowed in between the combustion air variable mechanism housing portion 51 and the bellows member 26 of the air introduction portion 21 is prohibited from flowing into the bellows member 26 and the tail cylinder 7. Thereby, as shown in FIG. 6, the NO _x emission amount that was about 65 ppm at the power generation output 25% is reduced to about 45 ppm.

When the power generation output reaches 50%, the controller closes the two combustion air variable mechanisms 20 as shown in FIG. As a result, as shown in FIG. 6, the NO _x emission amount in which the power generation output is increased to about 65 ppm at 50% is reduced to about 40 ppm. Further, when the power generation output reaches 75%, the controller closes all the four combustion air variable mechanisms 20 as shown in FIG. As a result, as shown in FIG. 6, the NO _x emission amount in which the power generation output increases to about 50 ppm at 75% is reduced to about 35 ppm. When the power generation output reaches 100%, the NO _x emission amount is about 40 ppm.

Thus, according to the combustion air variable mechanism of the present gas turbine combustor, in the 1,100 PS class simple open-cycle single-shaft small gas turbine as an example, four combustion air variable mechanisms 20 with respect to four bypass holes 8. the provided, by sequentially closing the valve body 31 toward the time of high output from the time of low power output of the gas turbine, the entire power range of the gas turbine, it is possible to suppress the NO _X emissions up to about 65 ppm, the low NO _X Can be promoted. That is, the air-fuel ratio of the gas turbine combustor 1 can be appropriately changed according to the output of the gas turbine.

Moreover, since the combustion air variable mechanism 20 described above is configured by including the air introduction part 21, the valve body 31, and the drive part 41, it can be reduced in size, and in particular, the air introduction part 21 constituting the bypass valve. And the valve body 31 are disposed in the outer cylinder 2 of the small gas turbine. Therefore, it is possible to reduce the cost, it is possible to enhance the low NO _X reduction. Furthermore, since the air cylinder 43 is operated by the compressor discharge air of the gas turbine, it is not necessary to separately provide a cylinder operating source.

  As described above, the variable combustion air mechanism 20 of the gas turbine combustor 1 is preferably implemented in a small gas turbine, but is not necessarily limited to a small gas turbine. It can also be implemented in a turbine. The combustion air variable mechanism 20 does not necessarily need to be provided for all the bypass holes 8, and does not need to be plural.

  On the other hand, although the serviceability is somewhat inferior, it is not always necessary to removably fit the air introduction portion 21 into the bypass hole 8 of the tail cylinder 7, and the air introduction portion 21 and the valve body 31 are not attached. It is not necessary to attach to the cylinder 2 detachably from the outside of the outer cylinder 2. Further, the valve body 31 is not opened / closed based on the power generation output of the gas turbine, the intake air temperature, the compressor outlet air pressure or shaft rotational speed, and the combustor inlet air temperature, but a part thereof. You may make it open and close based on other parameters or the combination of these and other parameters.

It is sectional drawing which shows the combustion air variable mechanism of the gas turbine combustor of this invention. It is sectional drawing which shows the detail of the combustion air variable mechanism of FIG. It is a top view which shows the valve seat of FIG. It is sectional drawing which shows the operation state different from FIG. FIG. 3 is a schematic diagram showing a state in which all of the valve body of FIG. 2 is opened. FIG. 3 is a schematic diagram showing a state in which one valve body of FIG. 2 is closed. FIG. 3 is a schematic diagram showing a state in which two valve bodies in FIG. 2 are closed. FIG. 3 is a schematic diagram showing a state where all the valve bodies in FIG. 2 are closed. It is a graph which shows the combustion control using the combustion air variable mechanism of FIG. It is sectional drawing which shows the conventional combustion air variable mechanism.

Explanation of symbols

Reference Signs List 1 combustor 2 outer cylinder 3 passage 5 inner cylinder 6 main combustor 7 tail cylinder 8 bypass hole 9 outlet 10 fixing pin 11 fuel injection nozzle 12 spark plug 20 combustion air variable mechanism 21 air introduction part 22 support plate 23 bellows member support part 24 Valve seat 25 Air insertion hole 26 Bellows member 27 Fitting part 31 Valve body 41 Drive part 42 Valve shaft 43 Air cylinder 51 Combustion air variable mechanism accommodating part 52 Lid member 53 Seal 54 Bolt 55 Nut 100 Combustor 101 Tail 102 Turbine 103 Combustion air variable mechanism 104 Bypass valve 105 Outer cylinder

Claims (8)

  A combustion air variable mechanism of a gas turbine combustor (1) having an outer cylinder (2) and an inner cylinder (5) having a bypass hole (8), wherein the combustion air variable mechanism (20) is cylindrical. Formed between the outer cylinder and the inner cylinder, extending outward from the bypass hole of the inner cylinder and flowing in between the outer cylinder and the inner cylinder. An air introduction portion (21) having a valve seat (24) formed at the outer end thereof while being introduced into the cylinder, and a valve contacted with the valve seat of the air introduction portion to close the inside of the compressor discharge air A combustion air variable mechanism for a gas turbine combustor, comprising: a valve body (31) that prohibits inflow into the cylinder; and a drive section (41) that opens and closes the valve body from the outside of the outer cylinder. .   The combustion of a gas turbine combustor according to claim 1, wherein the air introduction part (21) has a movable part (26) that moves flexibly in a radial direction and / or an axial direction of the inner cylinder (5). Air variable mechanism.   3. The gas turbine combustion according to claim 1, wherein an inner end portion of the air introduction portion (21) is removably fitted into the bypass hole (8) of the inner cylinder (5). Variable combustion air mechanism.   The said air introduction part (21) and the said valve body (31) are detachably fixed to the said outer cylinder (2) from the outer side of the said outer cylinder, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Variable combustion air mechanism of gas turbine combustor.   The bypass hole (8) and the combustion air variable mechanism (20) are composed of a plurality, and the combustion air variable mechanism sequentially closes the valve bodies (31) from a low output to a high output of the gas turbine. The combustion air variable mechanism of the gas turbine combustor according to any one of claims 1 to 4, wherein the variable combustion air mechanism is provided.   The said valve body (31) is opened and closed by the air cylinder (43) fixed to the outer side of the said outer cylinder (2), and the controller which controls the action | operation of the said air cylinder. The combustion air variable mechanism of the gas turbine combustor according to any one of claims 5 to 6.   The controller opens and closes the valve body (31) based on any one or more of the power generation output of the gas turbine, the intake air temperature, the compressor outlet air pressure or shaft rotational speed, and the combustor inlet air temperature. The combustion air variable mechanism of the gas turbine combustor according to claim 6.   The combustion air variable mechanism of a gas turbine combustor according to any one of claims 1 to 7, wherein the combustor (1) is a single cylinder type.

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