An overspeed protection system for a gas turbine generator set

Abstract

The present invention provides an overspeed protection system for a gas turbine generator set, ensuring the stable and safe operation of the gas turbine under different working conditions. It consists of a pneumatic controller, a solenoid valve, an accumulator, a pressure sensor, a bleed valve, a check valve, and a cooling and purification component, etc. During the starting process of the gas turbine, it provides compressed air for the gas turbine to open the anti-surge bleed valve and atomize fuel. After the gas turbine shuts down, it provides compressed air for the gas turbine to remove the residual fuel in the machine. When the gas turbine needs to shed load, it quickly opens all the bleed valves of the gas turbine. To improve the reliability and economy of the system, an accumulator is set in the gas turbine unit to store the high-pressure air after the compressor for controlling the load-shedding bleed valve. The present invention improves the safety and reliability of the operation of the gas turbine generator set and reduces the probability of accidents.

Description

Technical Field

[0001] The present invention relates to an overspeed protection system for gas turbine generator sets used in the shipbuilding industry and belongs to the energy and power industry. Background Art

[0002] The overspeed protection system for gas turbine generator sets is used for starting air release, low-load air release, load rejection air release of gas turbines, fuel atomization during gas turbine ignition, and fuel purge during gas turbine shutdown, ensuring the smooth start of gas turbines, having a high surge margin under low-load conditions, and no overspeed during sudden load rejection. Therefore, the overspeed protection system and its accessories are crucial for gas turbines. To prevent gas turbine surging, it is an effective means to release a part of the compressed air in the working condition range with a small surge margin of the gas turbine. For this reason, a quick-opening air release valve is set between the compressor stages. When the load of the generator set suddenly decreases, it is necessary to quickly reduce the output power of the gas turbine to prevent overspeed accidents. Therefore, an air release valve needs to be set behind the compressor. Summary of the Invention

[0003] The purpose of the present invention is to provide an overspeed protection system applied to gas turbine generator sets, which has the advantages of high safety, high reliability, easy maintenance, reasonable measuring point arrangement, and can ensure the stable and safe operation of gas turbines.

[0004] The purpose of the present invention is achieved as follows:

[0005] An overspeed protection system for gas turbine generator sets provided by the present invention is composed of a pneumatic controller, a solenoid valve, an accumulator, a pressure sensor, an air release valve, a check valve, and a cooling and purification assembly;

[0006] During the starting process of the gas turbine, when it is necessary to release air to increase the surge margin, the control system issues an instruction to open the pneumatic controller and the solenoid valve. High-pressure air enters the control chamber of the compressor stage air release valve through the solenoid valve, and then opens the compressor stage air release valve. The surge margin of the gas turbine is increased through inter-stage air release. When air release is not required, the control system issues an instruction to close the pneumatic controller and the solenoid valve, empty the control air in the control chamber of the compressor stage air release valve, and the air release valve closes under the action of the spring force and the flowing gas pressure. At the same time, the air release channel of the gas turbine is closed;

[0007] During the starting of the gas turbine, the solenoid valve is controlled by the control system to open, and compressed air is introduced into the fuel manifold to atomize the starting fuel and improve the combustion efficiency. After the compressor reaches a certain speed, the control system issues an instruction to close the solenoid valve and stop supplying compressed air to the fuel manifold. When the gas turbine shuts down, compressed air is introduced into the fuel manifold through the solenoid valve to purge the residual fuel in the fuel manifold and avoid potential safety hazards caused by fuel residue during the storage and custody of the gas turbine;

[0008] When the load of the gas turbine generator set suddenly drops or the power turbine speed exceeds the speed limit, the gas turbine output power needs to be reduced quickly. At this time, the control system issues a command to open all the bleed valves on the gas turbine, and at the same time discharge the air between the compressor stages and the air after the compressor, so as to achieve the purpose of quickly reducing the gas turbine speed to prevent overspeed accidents. When the gas turbine speed reaches a certain requirement, the bleed valves are closed one by one.

[0009] To ensure the normal and stable operation of the overspeed protection system, the main sources of high-pressure gas in the system are divided into two parts: the compressed air used to ensure fuel atomization and improve the surge margin of the gas turbine during the startup process comes from the compressed air provided by the air compressor of the peripheral system. The pressure requirement for this part of the gas does not need to be too high, and it is required to meet the fuel atomization requirements and the requirements for opening the bleed valve; the compressed air used when the gas turbine generator set needs to shed load to control the speed must be sufficient to open the high-pressure bleed valve, so the gas pressure requirement is relatively high, so this part of the gas comes from the air after the compressor of the gas turbine body, which is stored in the accumulator after the cooling and purification components, and a check valve is set at the outlet of the accumulator to ensure that the pressure in the accumulator is always consistent with the air pressure after the gas turbine compressor. When the gas turbine needs to control the speed by bleeding, the bleed valve can be quickly opened by controlling the gas in the accumulator.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] Ensure that the use requirements of the gas turbine generator set under different working conditions are fully met, including anti-surge bleed, load shedding bleed, starting fuel atomization, shutdown residual fuel discharge and other functions, thereby ensuring the safety and reliability of the gas turbine generator set operation and reducing the probability of accidents.

[0012] The pressure sensor is used to monitor the external gas source pressure and the pressure inside the accumulator, so that timely feedback can be given and effective measures can be taken when a system failure occurs.

[0013] The use of accumulators to collect and store high-pressure air reduces the requirements for the external air compressor station of the gas turbine generator system and improves economic efficiency.

[0014] A check valve is used to prevent fuel from flowing back into the solenoid valve or leaking out of the system when the gas turbine is running under high operating conditions, and the check valve is used to ensure that the air pressure in the accumulator can be kept equal to the maximum air pressure after the compressor under all operating conditions.

[0015] The invention is an overspeed protection system for a gas turbine generator set, which has high safety, high reliability, is easy to maintain, has reasonable arrangement of measuring points, and can ensure the stable and safe operation of the gas turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is the schematic diagram of the overspeed protection system for a gas turbine generator set. Specific implementation mode

[0017] The present invention will be further described below with reference to the accompanying drawings:

[0018] As Figure 1 shown, the overspeed protection system for a gas turbine generator set is composed of a pneumatic controller 1, solenoid valves 2, 3, 4, 6, an accumulator 5, pressure sensors 7, 14, bleed valves 8, 9, 11, 15, check valves 10, 13, and a cooling and purification assembly 12, and is characterized in that:

[0019] During the starting process of the gas turbine, when it is necessary to increase the surge margin by bleeding, the control system issues an instruction to open the pneumatic controller 1 and the solenoid valve 6. High-pressure air enters the control chambers of the compressor inter-stage bleed valves 8, 15 through the solenoid valve, and then the compressor inter-stage bleed valves 8, 15 are opened, and the surge margin of the gas turbine is increased by inter-stage bleeding. When bleeding is not required, the control system issues an instruction to close the pneumatic controller 1 and the solenoid valve 6, and the control air in the control chambers of the compressor inter-stage bleed valves 8, 15 is emptied. The bleed valves 8, 15 are closed under the action of the spring force and the flowing gas pressure, and at the same time, the bleed channel of the gas turbine is closed.

[0020] During the starting of the gas turbine, the control system controls the solenoid valve 3 to open and supplies compressed air to the fuel manifold to atomize the starting fuel and improve the combustion efficiency. After the compressor reaches a certain speed, the control system issues an instruction to close the solenoid valve 3 and stop supplying compressed air to the fuel manifold. When the gas turbine shuts down, compressed air is supplied to the fuel manifold through the solenoid valve 3 to purge the residual fuel in the fuel manifold and avoid potential safety hazards caused by fuel residue during the storage and custody of the gas turbine.

[0021] When the load of the gas turbine generator set suddenly drops or the power turbine speed exceeds the limit, it is necessary to quickly reduce the output power of the gas turbine. At this time, the control system issues an instruction to open the bleed valves 8, 9, 11, 15 on the gas turbine, and at the same time discharge the air between the compressor stages and the air after the compressor to quickly reduce the speed of the gas turbine and prevent overspeed accidents. When the speed of the gas turbine reaches a certain requirement, the bleed valves 8, 9, 11, 15 are closed one by one.

[0022] To ensure the normal and stable operation of the overspeed protection system, the main sources of high-pressure gas in the system are divided into two parts: the compressed air used to ensure fuel atomization and improve the surge margin of the gas turbine during the starting process comes from the compressed air provided by the air compressor in the peripheral system. For this part of the gas, the pressure requirement is not too high, and it only needs to meet the requirements of fuel atomization and the opening of the bleed valve. The compressed air used when the gas turbine generator set needs to shed load and control the speed should be sufficient to open the high-pressure bleed valve 11. Therefore, the pressure requirement for this part of the gas is relatively high. So, this part of the gas comes from the air after the compressor of the gas turbine body, passes through the cooling and purification module 12 and is stored in the accumulator 5. A check valve 13 is set at the outlet of the accumulator 5 to ensure that the pressure in the accumulator 5 is always consistent with the air pressure after the gas turbine compressor. When the gas turbine needs to control the speed by bleeding, the bleed valve can be quickly opened by the gas in the accumulator 5.

[0023] In summary, the present invention provides an overspeed protection system for a gas turbine generator set, which ensures the stable and safe operation of the gas turbine under different working conditions. It consists of a pneumatic controller, a solenoid valve, an accumulator, a pressure sensor, a bleed valve, a check valve, a cooling and purification module, etc. During the starting process of the gas turbine, compressed air is provided for the gas turbine to open the anti-surge bleed valve and atomize fuel. After the gas turbine stops, compressed air is provided for the gas turbine to remove the residual fuel in the machine. When the gas turbine needs to shed load, all the bleed valves of the gas turbine are quickly opened. To improve the reliability and economy of the system, an accumulator is set in the gas turbine unit to store the high-pressure air after the compressor for controlling the load-shedding bleed valve. The safety and reliability of the operation of the gas turbine generator set of the present invention are improved, and the probability of accidents is reduced.

[0024] The system of the present invention supplies high-pressure compressed air to the gas turbine generator set and conducts overspeed protection through the self-induced air of the gas turbine, ensuring that under the working conditions where bleeding is required, the gas turbine can open the low-pressure six-stage air bypass valve, the low-pressure rear air bypass valve, the high-pressure five-stage air bypass valve, and the high-pressure rear air bypass valve through the high-pressure control gas. At the same time, it ensures that high-pressure air can be delivered to the fuel manifold and fuel nozzles to ensure the normal starting and stable and safe operation of the gas turbine. The present invention fully meets the usage requirements of the gas turbine generator set under different working conditions, including functions such as anti-surge bleeding, load-shedding bleeding, starting fuel atomization, and residual fuel evacuation during shutdown.

Claims

1. A gas turbine generator set overspeed protection system, which consists of a pneumatic controller, a solenoid valve accumulator, a pressure sensor, a bleed valve, a check valve and a cooling and purification assembly. It is characterized in that: During the starting process of the gas turbine, the control system issues an instruction to open the pneumatic controller (1) and the first solenoid valve (6). The first high-pressure air opens the first and second bleed valves (8), (15). When bleeding is not required, the control system issues an instruction to close the pneumatic controller (1) and the first solenoid valve (6), and evacuates the control air in the control chambers of the first and second bleed valves (8), (15). The first and second bleed valves (8), (15) close under the action of spring force and the pressure of the flowing gas. When the gas turbine starts, the control system controls the second solenoid valve (3) to open and supplies compressed air to the fuel manifold to atomize the starting fuel. After the compressor reaches a certain speed, the control system issues an instruction to close the second solenoid valve (3) and stop supplying compressed air to the fuel manifold. When the gas turbine shuts down, compressed air is supplied to the fuel manifold through the first solenoid valve (3) to purge the residual fuel in the fuel manifold. When the load of the gas turbine generator set suddenly drops or the power turbine speed overspeed occurs, the control system issues an instruction to open the first, third, fourth and second bleed valves (8), (9), (11), (15) on the gas turbine, and simultaneously discharge the inter-stage air of the compressor and the air after the compressor. When the gas turbine speed reaches certain requirements, the first, third, fourth and second bleed valves (8), (9), (11), (15) are closed one by one. The second high-pressure air is the air after the compressor, which is stored in the accumulator (5) through the cooling and purification assembly (12), and a second check valve (13) is arranged at the outlet of the accumulator (5) to ensure that the pressure in the accumulator (5) is always consistent with the air pressure after the gas turbine compressor.

2. The gas turbine generator set overspeed protection system according to claim 1, characterized in that: The pressure sensor monitors the external air source pressure and the pressure in the accumulator, and can give timely feedback and take effective measures when the system fails.

3. The gas turbine generator set overspeed protection system according to claim 1, characterized in that: A first check valve (10) is also provided. The first check valve (10) prevents the fuel from flowing back into the solenoid valve or leaking to the outside of the system during the operation of the gas turbine under high working conditions, and ensures that the air pressure in the accumulator can maintain the same maximum pressure as the air pressure after the compressor under all working conditions through the second check valve (13).

4. The gas turbine generator set overspeed protection system according to claim 1, characterized in that: The first high-pressure air is the compressed air used to ensure fuel atomization and improve the gas turbine surge margin during the starting process. It comes from the compressed air provided by the peripheral system air compressor and can meet the requirements of fuel atomization and the opening of the first and second bleed valves (8), (15).

5. The gas turbine generator set overspeed protection system according to claim 1, characterized in that: The second high-pressure air is the compressed air used when the gas turbine generator set needs to shed load and control the speed. It can open the fourth high-pressure air bleed valve (11). When the gas turbine needs to control the speed by bleeding air, it can quickly control the opening of the fourth air bleed valve (11) through the gas in the accumulator (5).

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