JP4354052B2 - Cooling steam control method for gas turbine combustor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a cooling steam control method for a gas turbine combustor, which reduces the amount of cooling steam leakage, minimizes the mixing of steam into combustion air, and ensures combustion stability from start-up to steady-state operation. Thus, the flow rate, temperature, and pressure of the steam are controlled.
[0002]
[Prior art]
With the recent increase in the temperature of gas turbines, a system for cooling a combustor of a gas turbine with steam has begun to be adopted, and FIG. 2 is a schematic configuration diagram thereof. 10 is a gas turbine, 11 is a compressor, and 12 is a combustor that guides compressed air from the compressor 11, burns fuel to generate high-temperature combustion gas, and guides it to the gas turbine 10. The rotor of the gas turbine 10 And the generator connected to the gas turbine rotor is rotated. In order to generate a high-temperature gas, the combustor 12 is provided with a cooling passage 14 inside the wall, and steam is introduced into the cooling passage 14 and cooled by the steam. The cooling steam is extracted from the bottoming system of the steam turbine, guided to the cooling passage 14 of the combustor 12 via the pipe 15 and the on-off valve (shutoff valve) 13, and recovered by cooling the wall of the combustor 12. It is effectively used on the turbine side. In such a steam cooling system, the steam at the maximum pressure and flow rate required during steady operation from the start of the gas turbine is supplied to the cooling steam passage 14, and at present the steam flow rate and pressure are particularly during operation. It was not controlled.
[0003]
[Problems to be solved by the invention]
As described above, the cooling steam system of the gas turbine combustor passes through the external casing from the casing external piping, is led to the cooling steam header in the casing, is supplied to the combustor, and the recovered steam is conversely in the casing. From outside the cabin. In the course of the steam route in the passenger compartment, seal rings are used to alleviate the thermal expansion of each part. Steam leaks from these seal rings, or there is a slight amount in the cooling passage in the combustor wall. If there is a flaw, steam may escape from the cooling passage of the combustor.
[0004]
If the above-mentioned steam leakage occurs during startup of the gas turbine, during acceleration, or in a low load range, the steam will be mixed into the combustion air, resulting in unstable combustion and the amount of leaked steam. If there is a large amount, misfire may occur. Moreover, in such a steam cooling system, the steam pressure is normally higher than the combustion gas pressure (combustion side combustion air pressure) so that high-temperature combustion gas does not enter the steam pipe side. Steam is likely to leak to the combustor.
[0005]
Therefore, the present invention balances the steam pressure and the cabin pressure by controlling the steam pressure and flow rate in the high output range from the start, so that the steam pressure becomes the optimum pressure and flow rate, and the steam leakage An object of the present invention is to provide a cooling steam control method for a gas turbine combustor that supplies cooling steam in a state where the amount is minimized.
[0006]
[Means for Solving the Problems]
The present invention is to solve the problems described above, provides the following hand stage.
[0007]
A cooling steam is guided to a cooling passage (14 ) in a gas turbine combustor (12) to cool the combustor (12), and the cooling steam is supplied to the cooling passage (14) at the time of start-up. flow control valve provided in a bypass pipe for bypassing the cooling steam from the supply pipe (15) (16) (2) with the opening a predetermined amount, the cabin pressure force value, the minimum difference to prevent backflow of the cooling steam A bias to be a pressure is added to obtain a set value, and the flow rate control valve (2) provided in the bypass pipe (16) and the flow rate control valve ( provided in the supply pipe (15) so as to become this set value ( 4) The opening degree is controlled, and during the load operation, the steam temperature at the outlet of the cooling passage (14) is detected by the temperature detector (7) , and the supply pipe is set so as not to exceed the upper limit value of the outlet temperature. (15) the flow control valve provided in Thereby adjusting the cooling steam flow rate at 4), the pressure of the cooling steam detected by the upstream pressure detector provided in (6) of said flow control valve in the bypass pipe (16) (2) is predetermined the adjusted flow rate control valve (2) which is provided in the bypass pipe (16) so that the pressure, the cooling steam pressure is controlled to be higher by a predetermined pressure than the vehicle interior pressure When the engine is stopped, the on-off valve (5) for injecting dry air into the cooling passage (14) is opened for a predetermined time .
[0010]
This onset Ming, steam pressure guided into the cooling passages of the combustor because it is set slightly higher than the cabin pressure, it is possible to reduce the differential pressure between the vapor pressure and the cabin pressure. The amount of leaked steam is determined by this differential pressure, and the larger the differential pressure, the greater the amount of leaked steam. Therefore, to reduce the amount of leaked steam during ascending or in the low output range as much as possible, reduce this differential pressure. There is a need. For this reason, by controlling the steam pressure supplied to the combustor to the cabin pressure + “minimum differential pressure to prevent backflow”, contamination due to steam leakage into the combustion air can be minimized, In particular, combustion instability and misfire can be prevented while minimizing the influence on combustion during acceleration or in a low load range. In addition, in the present invention, when the engine is stopped, the on-off valve for injecting dry air into the cooling passage is opened for a predetermined time, thereby preventing the generation of drain due to the residence of steam in the steam system.
[0011]
Furthermore, the present invention sets a pressure value obtained by adding a slight pressure, that is, “minimum differential pressure for preventing backflow” to the vehicle interior pressure, and controls the pressure of the cooling steam to approach the target value. Mixing due to steam leakage into the air can be minimized, and instability and misfire can be prevented by minimizing the impact on combustion especially during acceleration or at low loads. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a control system diagram to which a cooling steam control method for a gas turbine combustor according to an embodiment of the present invention is applied. In the figure, 15 is a supply pipe through which cooling steam is guided, and the steam is extracted and guided from the bottoming system of the steam turbine. A flow control valve 2 bypasses the cooling steam of the combustor 12 and controls the supply pressure of the steam to the cooling passage 14 of the combustor 12. 3 is a shut-off valve, which opens and closes the supply steam to the combustor 12. A flow control valve 4 controls the steam flow rate to the cooling passage 14 of the combustor 12. An open / close valve 5 opens and closes the introduction of dry air for draining.
[0014]
A pressure detector 6 is provided on the upstream side of the flow rate control valve 2 in the bypass pipe 16 that bypasses the cooling steam from the supply pipe 15 that supplies the cooling steam to the cooling passage 14 and detects the steam pressure of the cooling steam . A temperature detector 7 detects the temperature of the outlet steam of the cooling passage 14 of the combustor 12. 8 is a pressure detector for detecting the steam pressure in the cooling passage 14 and comparing it with the air pressure in the passenger compartment.
[0015]
The control device 1 receives detection signals from the pressure detector 6, the temperature detector 7, and the pressure detector 8, respectively, and a flow rate control valve 2 that adjusts the supply pressure on the steam supply side as described later, combustion It controls the shut-off valve 3 of the combustor cooling system, the flow control valve 4 for supplying steam to the combustor 12, and the on-off valve 5 of the drain system.
[0016]
In the above configuration, the cooling steam of about 300 ° C. is led to the supply pipe 15 of the cooling steam system, the shut-off valve 3 is opened, and the steam is led to the cooling passage 14 of the combustor 12 via the flow control valve 4. Then, the combustor 12 is cooled, and the temperature becomes about 500 ° C. or higher by cooling, and is recovered. First, in order to warm up the steam system before starting, the shutoff valve 3 is opened slightly, the flow control valve is opened, the steam is allowed to flow through the cooling system, and warming is performed until the temperature detector 7 reaches a predetermined temperature. .
[0017]
At the time of start-up, the flow rate of the cooling steam may be small, and the control device 1 opens the flow control valve 2 by a predetermined amount, and controls the flow control valve 4 on the inlet side to flow the steam to the combustor 12. The steam pressure refers to the pressure of the pressure detector 8 and is set to a pressure slightly higher than the pressure in the passenger compartment. The control device 1 detects the pressure in the passenger compartment with a pressure detector ( not shown ), adds a bias that is “minimum differential pressure to prevent backflow of steam” to this pressure value, and sets it as a set value. The opening degree of the flow control valve 2 and the flow control valve 4 is controlled.
[0018]
During the load operation, the control device 1 detects the steam temperature at the outlet with the temperature detector 7 and controls the outlet steam temperature to be a predetermined load versus the set temperature, and does not exceed the upper limit value of the outlet temperature. Thus, the flow rate is controlled by adjusting the steam flow rate with the flow rate control valve 4. In this case, the supply pressure of the steam is adjusted by adjusting the flow rate control valve 2 provided in the bypass pipe 16 that bypasses the supply pipe 15 of the supply system so that the pressure detected by the pressure detector 6 becomes a predetermined pressure. And the vapor pressure flowing into the cooling passage 14 is controlled to be higher than the cabin pressure.
[0019]
When the gas turbine is stopped, the control device 1 opens the on-off valve 5 for a predetermined time by the gas turbine stop signal (or the rotation speed signal) and supplies dry air in order to prevent drain generation due to the stay of steam in the steam system.
[0020]
As described above, the control device 1 outputs detection signals from the respective detectors, that is, the pressure detector 6, the temperature detector 7, and the pressure detector 8, during warming, start-up, load operation , and stop. Intake, flow control valve 2, shut-off valve 3, flow control valve 4 and open / close valve 5 are controlled to control the steam pressure to an appropriate pressure slightly higher than the cabin pressure to prevent steam leakage and stable combustion. Ensure sex.
[0021]
A specific control example from the start to the load operation will be described. When the gas turbine ignition rotation speed is about 20% of the constant speed, the ignition state is stabilized at about 35% rotation speed. Therefore, in the first control method, when the rotation speed is 35% or less, the flow control valve 4 is throttled as much as possible to control the supply steam pressure to (chamber pressure) + (back flow prevention minimum differential pressure) and into the combustion air. In order to prevent combustion instability and misfire by minimizing the contamination of steam due to steam leakage and reducing the effect on combustion during ascending or in low load range. Above 35% rotation, the opening degree of the flow control valve 4 is gradually increased.
[0022]
The second control method, the pressure of the steam is detected by the pressure detector 8, (casing pressure) + 0.05~0.1μP _a) it was set to the control target value, the opening of the flow control valve 2 and 4 The degree of pressure is controlled to control the pressure and flow rate of steam to the cooling passage 14 of the combustor 12 so as to approach the target value. As a third control method, the pressure and flow rate of the cooling steam are controlled in the same manner as described above according to the fuel injection amount. When the fuel injection amount is large, the steam amount is large. When the fuel injection amount is small, the steam amount is also large. Proportional control is performed so as to reduce the steam pressure, and control is performed so that the steam pressure is slightly higher than the cabin pressure. Further, instead of the fuel injection amount, it may be proportional to the rotational speed.
[0023]
By setting the cooling steam pressure slightly higher than the passenger compartment pressure as described above and controlling it appropriately, it is caused by steam leakage into the combustion air, especially during the ascending and low power range of the gas turbine. Mixing can be minimized, unstable combustion of the combustor can be prevented, and misfire can also be prevented.
[0024]
【The invention's effect】
Cooling steam control method for a gas turbine combustor of the present invention leads to gas turbine combustor (12) cooling steam cooling passage to (14) in a method of cooling the same combustor (12), at startup The flow control valve (2) provided in the bypass pipe (16) for bypassing the cooling steam from the supply pipe (15) for supplying the cooling steam to the cooling passage (14) is opened by a predetermined amount, and the vehicle interior pressure A bias is set to a minimum differential pressure to prevent backflow of the cooling steam to the force value to obtain a set value, and the flow rate control valve (2) and the flow control valve (2) provided in the bypass pipe (16) so as to be the set value. The opening degree of the flow control valve (4) provided in the supply pipe (15) is controlled, and during the load operation, the steam temperature at the outlet of the cooling passage (14) is detected by the temperature detector (7). Do not exceed the upper limit of the outlet temperature Thereby adjusting the cooling steam flow rate in the supply pipe the flow control valve provided in (15) (4), said flow control valve (2) pressure detection provided upstream of the said bypass pipe (16) The flow control valve (2) provided in the bypass pipe (16 ) is adjusted such that the pressure of the cooling steam detected by the vessel (6) becomes a predetermined pressure, and the cooling steam pressure is adjusted to the vehicle. than chamber pressure is controlled to be higher by a predetermined pressure, at the time of stop, and the cooling passages (14) opening and closing valve for introducing dry air into the (5), characterized in that opening a predetermined time. According to such a way, contamination by leakage of steam into the combustion air can be minimized, especially to minimize the impact of the combustion in a speed-up phase, or low load region Combustion instability and misfire can be prevented.
[Brief description of the drawings]
FIG. 1 is a system diagram to which a cooling steam control method for a gas turbine combustor according to an embodiment of the present invention is applied.
FIG. 2 is a configuration diagram of a cooling steam system of a conventional gas turbine combustor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Control apparatus 2,4 Flow control valve 3 Shut-off valve 5 On-off valve 6,8 Pressure detector 7 Temperature detector 10 Gas turbine 12 Combustor
15 Supply piping
16 Bypass piping

Claims (1)

A method of directing cooling steam to a cooling passage (14 ) in a gas turbine combustor (12) to cool the combustor (12) ,
At startup, the flow control valve (2) provided in the bypass pipe (16) for bypassing the cooling steam from the supply pipe (15) for supplying the cooling steam to the cooling passage (14) is opened by a predetermined amount, and the vehicle chamber internal pressure force value, the reverse flow of cooling steam by adding bias the minimum differential pressure to prevent the setting value, the flow control valve provided in the bypass pipe so that the set value (16) (2 ) And the opening of the flow control valve (4) provided in the supply pipe (15) ,
During the load operation, the steam temperature at the outlet of the cooling passage (14) is detected by the temperature detector (7) , and the flow rate provided in the supply pipe (15) so as not to exceed the upper limit of the outlet temperature. thereby adjusting the cooling steam flow rate control valve (4), the pressure of the cooling steam is detected by said flow control valve in the bypass pipe (16) a pressure detector provided on the upstream side of (2) (6) wherein said flow rate control valve provided in the bypass pipe (16) (2) adjust the so that predetermined pressure, the so cooling steam pressure becomes higher by a predetermined pressure than the vehicle interior pressure Control to
A cooling steam control method for a gas turbine combustor , wherein the on-off valve (5) for injecting dry air into the cooling passage (14) is opened for a predetermined time when stopping .

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