JPH074265A - Gas turbine combustion part changing control method - Google Patents

Abstract

PURPOSE:To prevent repetition of ignition/extinguishment at each combustion part of a gas turbine having a multi-stage type combustor. CONSTITUTION:To a combustion command computed in accordance with deviation between a gas turbine load command 1 and a gas turbine load signal 2, logics of determining a fuel control changing zone by a changing zone controller 5, prohibiting a signal increase/decrease direction within the fuel control changing zone, determining passage of a re-entry allowing time are provided for avoiding frequency generation of large fuel quantity change at a combustion part. Consumption of a service lift by a rapid temperature change can, therefore, be restricted, with stable combustion maintained, and the lowest load can be reduced. The load command can thus be followed in a wide load range except for partial limit given in the fuel control changing zone if the load command with severe changing frequency is given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustion control, and more particularly to a gas turbine combustion section switching control method suitable for switching each combustion section of a combustor having a plurality of combustion sections.

[0002]

2. Description of the Related Art A cross-sectional view of a two-stage combustion type combustor adopting a premixing method and a gas turbine power generation system are shown in FIG.
The outlet air 10 from the compressor 9 is guided to the combustor 11, is burned with the fuel 18 and becomes the combustion gas 12, and flows into the turbine unit 13. The two-stage combustion combustor is composed of a first-stage combustion section 14 and a second-stage combustion section 15, the first-stage combustion section 14 uses a diffusion combustion method, and the second-stage combustion section uses combustion air 16 and a fuel nozzle 17. The pre-mixing system is adopted in which the fuel 18 and the fuel 18 are mixed and burned inside the swirler 19.

In the conventional gas turbine combustion section switching control method, as an example, the fuel distribution of a two-stage combustion type combustor is shown in FIG.
Shown in. GT is the fuel command for the entire gas turbine
With respect to the fuel command FT, a fuel distribution command F ₁ to the first-stage combustion section and a fuel distribution command F ₂ to the second-stage combustion section at the time of startup are shown. GT fuel command FT increases and specified value FTf
When the second stage combustion section is ignited,
The stage combustion section burns together. On the contrary, when the GT fuel command FT decreases to the specified value FTf when the fuel decreases, the second-stage combustion section extinguishes and only the first-stage combustion section burns. This ignition / extinguishing operation of the second-stage combustion section is accompanied by a rapid increase / decrease of fuel in the first-stage and second-stage combustion sections, causing a large temperature change in each combustion section and instability of combustion. / It is necessary to prevent frequent fire extinguishing. Further, once the GT fuel command FT exceeds the specified value FTL ₂ , the specified value FTL ₂ is set to the minimum value of the GT fuel command FT to prevent repeated ignition / extinction.

[0004]

In the conventional gas turbine combustion section switching control method, when the fuel command decreases to the specified value, the second stage combustion section is extinguished and only the first stage combustion section is burned. The ignition / extinguishing operation of the second-stage combustion section is
There has been a problem that a rapid temperature increase / decrease of the fuel in the first and second stage combustion sections causes a large temperature change in each combustion section, resulting in an increase in equipment life consumption and instability of combustion. Further, there is a problem that the minimum value of the gas turbine load is limited by the load corresponding to the ignition / fire extinguishing command of the second stage combustion section.

An object of the present invention is to prevent frequent ignition / extinguishing of each combustion section of a gas turbine having a multi-stage combustor to suppress equipment life consumption, maintain stable combustion, and reduce minimum load. A gas turbine combustor switching control method that can be performed is provided.

[0006]

In order to achieve the above-mentioned object, a gas turbine combustion section switching control method according to the present invention comprises:
In the gas turbine combustion unit switching control method, which has a plurality of combustion units and switches the fuel distribution command to each combustion unit according to the increase or decrease of the fuel command, in the gas turbine combustion unit switching control method A fuel control switching band is provided in the vicinity of the fuel command for switching the fuel control switch band, and the switching band controller determines whether or not the fuel command is passing through the fuel control switching band, and prohibits reversing the increasing / decreasing direction of the fuel command while the fuel command is passing. And

The fuel control switching band may have a fuel command width in which a fluctuation margin is added to a fuel command for switching ignition or extinction of at least one combustion section.

Further, the fuel command may be increased or decreased at a rate of change equal to or more than a predetermined rate while passing through the fuel control switching zone.

Further, the fuel command may be configured to increase or decrease after a lapse of a specified time when the fuel command reaches the upper limit or the lower limit after passing through the fuel control switching zone and again passes through the fuel switching zone by increasing or decreasing.

Then, the gas turbine combustion section switching control device is configured to use any one of the gas turbine combustion section switching control methods described above.

[0011]

According to the present invention, a fuel control switching zone with a certain margin is provided before and after the specified value for ignition / extinction of the second stage combustion section with respect to the GT fuel command (fuel command), and the fuel control is performed. When the GT fuel command enters the lower limit in the increasing direction in the switching zone, it is always raised to the upper limit of the fuel control switching zone, and conversely, when the GT fuel command enters the upper limit in the decreasing direction, it is lowered to the lower limit of the fuel control switching zone. In addition, once the fuel control switching band is reached and the upper limit is reached, the condition of completion of elapse of the specified allowable time until the reduction command to pass the fuel control switching band again is taken in, which often causes an adverse effect on the combustion unit. It is possible to prevent repeated ignition / extinguishing, and to suppress the life consumption of the gas turbine equipment due to the switching of the gas turbine combustion section. Further, it becomes possible to increase or decrease the gas turbine load in a wide range including the fuel control switching zone while suppressing the combustion instability within the limit, and it is possible to reduce the minimum load of the gas turbine for load control.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing the concept of the present invention, and the internal configurations of the gas turbine power generation system and the combustor shown in FIG. 5 are the same in the present invention. Further, the fuel distribution system of the first stage combustion unit and the second stage combustion unit is also the system shown in FIG.

As shown in FIG. 1, the GT fuel command (fuel command) FT decreases and reaches the upper limit FTL ₂ of the fuel control switching band FTB from time t ₀ to t ₁ . Further, it is recognized that the GT fuel command has decreased and entered the fuel control switching band FTB, and the increasing direction command FTa of the GT fuel command is prohibited until the lower limit FTL ₁ of the fuel control switching band FTB is reached.

GT fuel command is time t₂Fuel control switching zone
Lower limit of FTB FTL₁If the GT fuel command is reached,
To enter the fuel control switching zone FTB again, the lower limit FTL₁To
After reaching the specified time T₁Time is determined by
T₁Lower limit FTL while does not elapse ₁Above is the GT fuel command
The increasing direction command FTb is prohibited. This control method is
When the fuel charge passes through the fuel control switching zone FTB in the increasing direction
The same applies to the case where the fuel control switching zone FTB is decreasing.
Command FTc is prohibited.

The upper limit FTL ₂ of the fuel control switching zone FTB
After once reaching, the fuel command FTd that reenters the fuel control switching zone FTB is prohibited until the specified time T ₂ elapses. The specified times T ₁ and T ₂ are set in consideration of the life consumption of the equipment and the stability of combustion, and in some cases even zero hours can be tolerated.

FIG. 2 shows a control block diagram of this embodiment. Gas turbine load command 1 and gas turbine load signal 2
The difference between and is calculated by the subtracter 3 and the fuel command for the gas turbine is created by the control calculator 4 such as proportional control or proportional-integral control. In the prior art, this fuel command is directly
It is input to the stage-stage combustion part fuel distributor 6 and the second-stage combustion part fuel distributor 7, and outputs F ₁ and F ₂ of the respective distributors become fuel distribution command signals for the first-stage and second-stage combustion parts. Was there. In this embodiment, the switching band controller 5 is inserted after the control calculator 4.
The contents of the switching band controller 5 incorporates the control method of the fuel control switching band previously described in FIG. That is, the switching band controller determines whether the fuel command is passing through the fuel control switching band, a circuit A, a circuit B that prohibits the fuel command from changing in the increasing / decreasing direction while the fuel command is passing through the fuel control switching band, and the fuel. The command C is provided with a circuit C or the like for determining the elapse of a prescribed time period for permitting the reentry of the fuel control switching zone.

As a concrete logic diagram of this control circuit, an example of the fuel switching permission judgment circuit is shown in FIGS. 3 and 4. The fuel command FT drops, and the lower limit FTL ₁ of the fuel control switching band FTB ₁
Is stored, the condition that the predetermined time T ₁ has elapsed and the fuel command FT is the lower limit F of the fuel control switching zone FTB.
When the condition is larger than TL _{1, the} operation of increasing the fuel command FT is permitted, and the fuel command FT can be increased. Further, the fuel command FT rises and the upper limit FTL of the fuel control switching band FTB is increased.
₂ is stored, the condition that the predetermined time T ₂ has elapsed and the fuel command FT is the lower limit F of the fuel control switching zone FTB.
When the condition is smaller than TL _2, the lowering operation of the fuel command FT is permitted and the fuel command FT can be lowered. The GT fuel command in the fuel control switching zone may follow the output command of the control computing unit 4 unless the signal is inverted. However, in order to shorten the stay in the fuel control switching zone, the GT fuel command once enters the fuel control switching zone. In this case, a method of increasing or decreasing to the upper limit side or the lower limit side of the fuel control switching zone at the rate of change above the specified rate is also effective.

According to the present invention, when there is a switching operation of the combustion section of a gas turbine having a two-stage combustor, even if a load command with a large change frequency is given, a partial restriction in the fuel control switching zone is performed. With the exception of being attached, the load command can be followed in a wide load range. That is, the gas turbine load control command range can be expanded by providing the minimum switching repetition prohibition condition, and the gas turbine minimum load can be reduced, and a wide range of operations can be achieved. Further, the present invention can be applied not only to the two-stage combustor but also to a gas turbine having a combustor with a larger number of switching operations of the combustion section.

[0019]

According to the present invention, since the fuel control switching zone is provided in the fuel command of the gas turbine having the multi-stage combustor, frequent ignition / extinction of each combustion section is prevented and a rapid temperature change is caused. It is possible to suppress the lifespan of the equipment, maintain stable combustion, and reduce the minimum load.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a fuel control switching band of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a fuel switching permission determination circuit of FIG.

FIG. 4 is a diagram showing an example of a fuel switching permission determination circuit of FIG.

FIG. 5 is a diagram showing a cross section of a two-stage combustor.

FIG. 6 is a diagram showing a fuel distribution method for a conventional two-stage combustor.

[Explanation of Codes] 1 gas turbine load command 2 gas turbine load signal 3 subtractor 4 control calculator 5 switching zone controller 6 first stage combustion part fuel distributor 7 second stage combustion part fuel distributor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Shimura, 1-1 1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor, Hiroshi Hanaoka 3-chome, Saiwaicho, Hitachi, Ibaraki No. 1 Hitachi Ltd., Hitachi Works (72) Inventor Minoru Takaba 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi, Ltd. (72) Koji Takahashi Ibaraki, Hitachi City 3-1-1 Machi, Hitachi, Ltd. Hitachi factory (72) Inventor, Masae Takahashi 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Omika factory (72) Inventor, Shiromaru Isao Hiroshima No. 4-33, Komachi, Naka-ku, Hiroshima-shi, Chugoku Electric Power Co., Inc. (72) Inventor Chiyori Toriya, No. 4-33, Komachi, Naka-ku, Hiroshima-shi, Hiroshima (72) Inventor Yamamoto Kiyomi, Chugoku Electric Power Co., Inc. 4-33 Komachi, Naka-ku, Hiroshima City, Hiroshima Prefecture

Claims (5)

[Claims] 1. A gas turbine combustion section switching control method comprising a plurality of combustion sections and switching a fuel distribution command to each combustion section according to an increase or decrease of a fuel command to control ignition or extinction of each combustion section, A fuel control switching band is provided in the vicinity of the fuel command for switching each fuel distribution command, and a switching band controller determines whether or not the fuel command is passing through the fuel control switching band and the fuel command is passed during the passing. A method for controlling switching of a gas turbine combustor, wherein reversal of the increasing / decreasing direction is prohibited. 2. The gas turbine combustion section switching according to claim 1, wherein the fuel control switching zone has a fuel command width in which a variation allowance is added to a fuel command for switching ignition or extinction of at least one combustion section. Control method. 3. The gas turbine combustion unit switching control method according to claim 1, wherein the fuel command is increased or decreased at a predetermined change rate or more while passing through the fuel control switching zone. 4. The fuel command is increased or decreased after a lapse of a prescribed time when the fuel command reaches the upper limit or the lower limit after passing through the fuel control switching zone and again passes through the fuel switching zone by increasing or decreasing. The method for controlling switching of a gas turbine combustion unit according to claim 1. 5. A gas turbine combustion unit switching control device using the gas turbine combustion unit switching control method according to any one of claims 1 to 4.