JPH07301129A - Gas turbine combustion device and control method therefor - Google Patents

Abstract

PURPOSE:To perform stable combustion wherein an NOx temperature is kept at a constant value by a method wherein a flow rate of fuel or air is distributed and controlled by using a signal responding to a change amount of NOx density and distribution between a flow rate of fuel and air fed to a diffusion combustion part and a flow rate of air fed to a premixture combustion part is set. CONSTITUTION:A combustion device 3 comprises a diffusion combustionpart 5; and a premixture combustion part 6. An air flow rate regulator 11 is arranged in the air inflow hole of a premixer 10 to regulate an inflow air flow rate. A flow rate of total fuel to a combustion device is branched at the inlet of the combustion device into a flow rate form diffusion combustion and a flow rate for premixture combustion. A signal from a deviation value from reference NOx density is fed to a fuel distribution corrector 17 and an air flow rate regulation corrector 18 through an NOx density measuring apparatus 16. Distribution of fuel is regulated in a way that a signal for a fuel distribution setter 13 is added and an air flow rate is regulated in a way that a signal for an air flow rate regulation setter 15 is added. Thus, a fuel flow rate ratio and an air flow rate at each stage are regulated and NOx density is kept at a reference set value to effect stable combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a gas turbine combustion apparatus and control method therefor, and more particularly to a combustion apparatus having a diffusion combustion section and a premix combustion section and a control method therefor.

[0002]

2. Description of the Related Art NOx generated during combustion of natural gas, kerosene, gas oil or the like is thermal NOx generated by oxidizing nitrogen in the air. The generation of this thermal NOx has a high temperature dependency, and in a gas turbine that generally uses a fuel with a low nitrogen content, reduction of the flame temperature is the basic idea of the low NOx combustion method.

The combustion device of a gas turbine is significantly different from the combustion device used in a general boiler or the like. That is, the point that the fuel flow rate changes according to the load is the same, but in the case of a gas turbine, the air flow rate is almost constant regardless of the load, and the fuel-air ratio, which is the mass flow rate ratio of fuel and air, is There is a large change from partial load to 100% rated load.

Even in the vicinity of the rated load at which the fuel flow rate becomes maximum, a large amount of air, which is almost twice the theoretical air amount required for complete combustion of fuel, is supplied. Therefore, lean combustion in which a flame is formed with a large excess of air can be applied, and this is the mainstream technology of the NOx reduction method adopted in the present combustor.

The combustion method of gaseous fuel is roughly classified into a diffusion combustion method in which fuel and air are burned while being mixed, and a premixed combustion method in which fuel and air are mixed in advance and ejected from a nozzle to burn. It

Diffusion combustion is excellent in flame stability and can form a stable flame in a wide fuel-air ratio range. However, since fuel and air burn while mixing, the fuel-air ratio changes spatially in the flame. However, even if a lean burn is tried, a part of the fuel burns in an excessive fuel state. Therefore, the flame temperature locally rises, and a large amount of NOx is easily generated.

In this point, in premixed combustion, the fuel and air are mixed before being introduced into the combustion chamber. Therefore, it is easier to make the fuel-air ratio in the flame more uniform than in the diffusion combustion, and local mixing due to nonuniformity of mixing is facilitated. The premixed combustion is N
The effect of reducing Ox is great.

A gas turbine combustion apparatus generally has a two-stage combustion section, that is, a diffusion combustion section and a premixed combustion section, and thus has a diffusion combustion section and a premixed combustion section. In the gas turbine combustor, it is effective to reduce NOx by decreasing the diffusion combustion ratio and increasing the premix combustion ratio.

However, as described above, the premixed combustion has a drawback that the fuel-air ratio capable of stably forming a flame is narrower than that of the diffusion combustion. Generally, the lower the fuel-air ratio is, the more N
Although the Ox concentration decreases, carbon monoxide (C
O) emission increases, combustion oscillation is likely to occur, and a misfire may occur in some cases. That is, it becomes an unstable combustion state.

Further, NOx is easily influenced by atmospheric temperature and atmospheric humidity. When the atmospheric temperature decreases and the atmospheric humidity increases, NOx decreases, but it causes unstable combustion.

From these points, for example, JP-A-63-3
In JP 11025, the NOx concentration for judging stable combustion is confirmed in advance, and when the NOx concentration becomes higher than the concentration for stable combustion, the ratio of the fuel flow rate supplied to the premix combustion section is increased, and the NOx concentration is increased. When the concentration becomes lower than the stable combustion, the ratio of the flow rate of the fuel supplied to the premixed combustion unit is adjusted to be decreased to control the stable combustion.

[0012]

The method of judging and controlling the combustion state based on the NOx concentration as in the conventional combustion apparatus is certainly effective, however, the currently popular NOx concentration measuring apparatus responds to it. Since it takes time, even if the NOx concentration is judged to be unstable combustion, it cannot be sensed instantly, the response is delayed, and there is a dislike that stable combustion control cannot be performed.

Further, since the response of the NOx concentration measurement is delayed, the amount of ammonia used for denitration becomes excessive or insufficient depending on the response, which is not preferable.

The present invention has been made in view of this, and an object thereof is to control NOx concentration constantly so that the response delay of the NOx concentration measuring device does not cause a problem as much as in the prior art, and it is used for denitration. It is an object of the present invention to provide a gas turbine combustor of this kind and a control method thereof for keeping the amount of ammonia constant.

[0015]

That is, the present invention is NO
The fuel distribution control or the air flow distribution control is performed by using the signal corresponding to the change amount of the x concentration, and the distribution of the fuel flow rate or the air flow rate to be supplied to the diffusion combustion section and the premix combustion section is set to determine the NOx concentration. If the concentration is higher than a predetermined concentration, the fuel flow rate distribution to the premix combustion unit is reduced or the air flow rate is increased, and if the NOx concentration is lower than the predetermined concentration, the premix combustion unit is The fuel flow rate distribution is increased or the air flow rate is decreased to achieve the intended purpose.

[0016]

[Operation] That is, with such a control method,
That is, the ratio of the flow rate of the fuel supplied to the diffusion combustion section and the premixed combustion section and the air flow rate are adjusted.
The concentration is constantly controlled to a predetermined reference set value, that is, the NOx concentration is always kept at the reference set value and stable combustion can be achieved, and further, the problem of the responsiveness of the NOx concentration meter disappears, and the excess NOx removal ammonia and It will be economical without shortage.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 systematically shows the two-stage combustion type gas turbine combustion apparatus and related apparatus.

The gas turbine is mainly composed of a compressor 1 for generating combustion air, a turbine 2 for converting the injection force of the combustion gas into a rotational force, and a combustion device 3 for generating high temperature and high pressure combustion gas.

The compressed air from the compressor 1 is guided to the combustion device 3 and becomes combustion gas 4 in the combustion device and flows into the turbine 2. The combustion device 3 includes a diffusion combustion section 5 and a premix combustion section 6. In the diffusion combustion unit 5, the fuel nozzle 7
The fuel 7a (F1) ejected further is combusted by the air flowing in from the combustion air holes provided on the combustion cylinder wall, and the fuel 8a (F1) ejected from the fuel nozzle 8 in the premixed combustion section.
2) is mixed with the air 9 in the premixer 10 and then introduced into the combustion chamber and burned.

An air flow rate adjuster 11 for adjusting the area of the inflow hole is installed in the air inflow hole of the premixer 10 to adjust the air flow rate flowing into the premixer.

The total flow rate of fuel injected into the combustion device is set by the load command device 12 of the gas turbine, and branched at the inlet of the combustion device through the fuel distribution setting device 13 into diffusion combustion and premixed combustion. It

Only the diffusion flame is formed at the time of starting the gas turbine and at the time of low load operation, the premix combustion fuel 8a is injected at a certain load, and the high temperature combustion gas from the diffusion combustion section 5 is used as the premix combustion fuel. 8a is ignited. Diffusion combustion and premixed combustion are used together when the gas turbine is operated above the load at which the premixed flame is formed.

The operating conditions of the combustion device are set by the combustion control device 14 and the air flow rate adjusting / setting device 15.

The NOx concentration is measured by sampling from the gas turbine exhaust gas, and the NOx concentration measuring device 16
The deviation of the NOx concentration as a reference is sent to the fuel distribution compensator 17 and the air flow rate adjustment compensator 18 as a signal.

The fuel distribution is adjusted by adding the signal from the fuel distribution corrector and the signal from the fuel distribution setting unit 13 to the proper fuel distribution. Further, in adjusting the air flow rate, the signal from the air flow rate adjustment compensator 18 and the signal from the air flow rate adjustment setting device 15 are added to adjust to an appropriate air distribution.

At this time, when the NOx concentration is higher than the predetermined concentration, a signal for reducing the premixed combustion fuel 8a is sent to the fuel distribution compensator so that the NOx concentration becomes the predetermined concentration. A signal for adjusting the distribution or for increasing the premixed combustion air 9 is sent to the air flow rate adjusting / correcting device 18 to adjust the air flow rate adjusting device so that the NOx concentration becomes a predetermined concentration.

On the other hand, when the NOx concentration is lower than the predetermined concentration, a signal for increasing the premixed combustion fuel 8a is sent to the fuel distribution compensator to distribute the fuel so that the NOx concentration becomes the predetermined concentration. A signal for adjusting or reducing the premixed combustion air 9 is sent to the air flow rate adjusting / correcting device 18 to adjust the air flow rate adjusting device so that the NOx concentration becomes a predetermined concentration.

With such a control method, the ratio of the fuel flow rate supplied to each stage and the air flow rate are adjusted, whereby the NOx concentration is constantly controlled to a predetermined reference set value, and the NOx concentration is always constant. It is economical to control the NOx concentration measurement device as much as the conventional combustion device does, and it is economical because the amount of ammonia used for denitration does not become excessive or insufficient, and the combustion stability is increased. Things can come out.

That is, since the NOx concentration is controlled to be constant at all times, stable combustion is maintained and highly reliable low NOx concentration is maintained.
Can be used as a combustion device.

[0030]

As described above, according to the present invention, the ratio of the fuel flow rate supplied to each stage and the air flow rate are adjusted so that the NOx concentration is constantly controlled to a predetermined reference set value. That is, the NOx concentration is always kept at the standard set value, stable combustion can be achieved, the problem of the responsiveness of the NOx concentration measuring instrument is eliminated, and the denitration ammonia does not become excessive or insufficient, which is economical.

[Brief description of drawings]

FIG. 1 is a system diagram of a combustion device of the present invention and its peripheral devices.

[Explanation of symbols]

1 ... Air compressor, 2 ... Turbine, 3 ... Combustion device, 12 ...
Load command device, 14 ... Fuel control command device, 16 ... NOx
Concentration measuring device.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location F23R 3/34 (72) Inventor Yasutaka Komatsu 3-1-1 1-1 Saiwaicho, Hitachi City, Ibaraki Stock Association Company Hitachi, Ltd. Hitachi factory (72) Inventor Shiromaru Isao 4-33 Komachi, Naka-ku, Hiroshima City, Hiroshima Prefecture Chugoku Electric Power Co., Inc. (72) Inventor Osamu Toriya 4-33 Komachi, Naka-ku, Hiroshima City, Hiroshima, China Electric Power Co., Ltd. (72) Inventor Akimasa Hasegawa 4-33 Komachi, Naka-ku, Hiroshima City, Hiroshima Prefecture Chugoku Electric Power Co., Inc.

Claims (9)

[Claims] 1. A flow rate of fuel and an air flow rate supplied to the diffusion combustion unit and the premixing combustion unit in accordance with the output load of the combustion apparatus, each stage having at least one diffusion combustion unit and one premixing combustion unit. In a method of controlling a gas turbine combustion device, which is adapted to adjust the above, a predetermined NOx concentration during operation is set in advance, and the NOx concentration measured during operation is always kept constant at this specified NOx concentration. A method for controlling a gas turbine combustion apparatus, characterized in that a ratio of fuel flow rates supplied to the diffusion combustion section and the premixed combustion section is controlled. 2. A flow rate of fuel and an air flow rate which are provided to at least one diffusion combustion section and one premixed combustion section and are supplied to the diffusion combustion section and the premixed combustion section in accordance with the output load of the combustion apparatus. In a method of controlling a gas turbine combustion apparatus, which is adapted to adjust the above, a predetermined NOx concentration during operation is set in advance, and the NOx concentration measured during operation is always kept constant at this specified NOx concentration. A method for controlling a gas turbine combustion apparatus, characterized in that the ratio of the flow rates of air supplied to the diffusion combustion section and the premixed combustion section is controlled. 3. A flow rate of fuel and an air flow rate supplied to the diffusion combustion section and the premixing combustion section according to the load of the output of the combustion apparatus, which has at least one stage of each of the diffusion combustion section and the premixing combustion section. In a method for controlling a gas turbine combustion apparatus, the NOx concentration is higher than a predetermined concentration, the ratio of the fuel flow rate supplied to the premix combustion unit is increased to increase the NOx concentration.
A method for controlling a gas turbine combustion device, wherein the concentration is adjusted within a predetermined concentration range. 4. A diffusion combustion section and a premixed combustion section each having one stage or a plurality of stages, and the flow rate of fuel supplied to each stage and the flow rate of air supplied to each stage according to the load of the turbine. In a method for controlling a gas turbine combustion device configured to adjust the NOx concentration, when the NOx concentration becomes higher than a predetermined concentration, the ratio of the fuel flow rate supplied to the premix combustion unit is increased to increase the NOx concentration.
A method for controlling a gas turbine combustion device, wherein the concentration is adjusted within a predetermined concentration range. 5. A diffusion combustion section and a premixed combustion section each having one stage or a plurality of stages, and the flow rate of fuel supplied to each stage and the flow rate of air supplied to each stage according to the load of the turbine. In a method for controlling a gas turbine combustion device configured to adjust the NOx concentration, when the NOx concentration becomes higher than a predetermined concentration, the ratio of the air flow rate supplied to the premix combustion unit is increased to increase the NOx concentration.
A method for controlling a gas turbine combustion device, wherein the concentration is adjusted within a predetermined concentration range. 6. A diffusion combustion section and a premixed combustion section each having one stage or a plurality of stages, and the flow rate of fuel supplied to each stage and the flow rate of air supplied to each stage according to the load of the turbine. In the control method of the gas turbine combustion device, which is formed so as to adjust the NOx concentration when the NOx concentration becomes lower than a predetermined concentration, the fuel ratio supplied to the premixed combustion unit is reduced to set the NOx concentration in advance. A method for controlling a gas turbine combustion device, characterized in that the concentration is adjusted. 7. A flow rate of fuel supplied to each stage and a flow rate of air supplied to each stage, each having one stage or a plurality of stages of the diffusion combustion unit and the premixed combustion unit, according to the load of the turbine. In the control method of the gas turbine combustion device, which is formed to adjust the NOx concentration, when the NOx concentration becomes lower than a predetermined concentration, the flow rate of the air supplied to the premix combustion unit is reduced to set the NOx concentration to a predetermined value. A method for controlling a gas turbine combustion device, characterized in that the concentration is adjusted. 8. A fuel flow rate adjustment device that includes at least one stage of each of the diffusion combustion unit and the premixed combustion unit, and that adjusts the flow rate of the fuel supplied to the diffusion combustion unit and the premixed combustion unit according to the load of the output of the combustion device. A gas turbine combustion apparatus comprising an apparatus and an air flow rate adjusting apparatus for adjusting the flow rate of air, the apparatus comprising: N for measuring the concentration of NOx during operation.
The NOx concentration measuring device compares the NOx concentration value measured by the NOx concentration measuring device with a certain NOx concentration value, and the NOx concentration value measured by the NOx concentration measuring device is determined by the certain amount. A gas turbine combustion apparatus, comprising: a control device that controls a ratio of a fuel flow rate supplied to the diffusion combustion unit and the premixing combustion unit so as to obtain a NOx concentration value. 9. A fuel flow rate adjustment device having at least one stage of each of the diffusion combustion section and the premixed combustion section, and adjusting the flow rate of the fuel supplied to the diffusion combustion section and the premixed combustion section according to the output load of the combustion device. A gas turbine combustion apparatus comprising an apparatus and an air flow rate adjusting apparatus for adjusting the flow rate of air, the apparatus comprising: N for measuring the concentration of NOx during operation.
The NOx concentration measuring device compares the NOx concentration value measured by the NOx concentration measuring device with a certain NOx concentration value, and the NOx concentration value measured by the NOx concentration measuring device is determined by the certain amount. A gas turbine combustion apparatus, comprising: a controller for controlling a ratio of an air flow rate supplied to the diffusion combustion section and the premixed combustion section so as to obtain a NOx concentration value.