A sealing oil supply system for a gas and steam combined cycle unit

Abstract

The present application relates to the technical field of gas and steam combined cycle unit, and discloses a sealing oil supply system of a gas and steam combined cycle unit, which is suitable for a new power system and comprises a gas turbine, a steam turbine, a generator, a main pipeline connected with the gas turbine, the steam turbine and the generator, sealing shoes, an oil tank, a lubricating oil pump set and an alternating sealing oil pump set. During long-term standby of the unit, the alternating sealing oil pump is started to meet the sealing effect of the sealing shoes of the engine, and the lubricating oil pump set and the closed cooling pump are stopped, so that the effects of saving electricity and energy are achieved. When the lubricating oil system needs to be stopped for maintenance due to running, dripping, lubricating oil pump abnormality or damage of the main engine bearing shoe, etc., the alternating sealing oil pump can ensure stable operation of the hydrogen and sealing oil system of the generator, hydrogen replacement is not needed, hydrogen leakage and oil entering into the generator are eliminated, the risk of hydrogen explosion is eliminated, and the safety of the system is further improved.

Description

Technical Field

[0001] This invention relates to the field of gas-steam combined cycle units, and more specifically to a sealing oil supply system for gas-steam combined cycle units. Background Technology

[0002] In gas-steam combined cycle units, the generator is cooled by water-hydrogen or all-hydrogen. Since the generator rotor must protrude through the generator end cover, hydrogen inside the generator may leak out. Therefore, a sealing oil system must be used to supply sealing oil at a pressure slightly higher than the hydrogen pressure to the generator sealing tiles to prevent hydrogen leakage.

[0003] Under the new power system, the amount of new energy power generation continues to increase, and the supply of natural gas is tight. Gas-steam combined cycle units need to be on standby for a long time and have few opportunities to start up, making the power generation situation very severe. During the period when the unit is out of service, in order to ensure that the unit is in standby status, hydrogen is kept running in the generator. Under these circumstances, the lubrication system must be kept running for a long time. At the same time, in order to ensure the temperature of the lubrication oil, the closed cooling water system still needs to be running.

[0004] Taking two GE 9FA heavy-duty single-shaft gas-steam combined cycle units in a certain factory as an example, the average annual operating hours are 1080 hours. The units have a low utilization rate throughout the year, with peak operation in summer and autumn and long-term standby in winter and spring. If the lubrication system needs to be shut down, the hydrogen in the generator must be replaced with CO2. Each replacement requires 50 bottles of CO2 and the replacement process takes more than 24 hours. Once the unit has a startup plan, it will be difficult to meet the startup requirements. Summary of the Invention

[0005] In view of this, the present invention provides a sealing oil supply system for a gas-steam combined cycle unit to solve the problem of how to ensure the stable operation of the generator hydrogen and sealing oil system during long-term standby of the unit.

[0006] In a first aspect, the present invention provides a sealing oil supply system for a gas-steam combined cycle unit, applicable to novel power systems. The sealing oil supply system for the gas-steam combined cycle unit includes a gas turbine, a steam turbine, and a generator connected in sequence, and a main pipeline suitable for connection to the gas turbine, the steam turbine, and the generator; further comprising: Sealing tiles are disposed on both sides of the generator; the sealing tiles are adapted to seal the generator and prevent gas leakage from the generator. The oil tank is designed to store lubricating oil. A lubricating oil pump assembly, with its input end adapted to communicate with the oil tank and its output end connected to the main pipeline; the lubricating oil pump assembly is adapted to be connected to both sides of the gas turbine, both sides of the steam turbine, and both sides of the generator via the main pipeline; the lubricating oil pump assembly is adapted to provide lubricating oil to the bearings of the gas turbine, the steam turbine, and the generator respectively via the main pipeline; An AC sealing oil pump assembly is provided, wherein the input end of the AC sealing oil pump assembly is adapted to be connected to the oil tank, and the output end of the AC sealing oil pump assembly is adapted to be connected to the main pipeline; the AC sealing oil pump assembly is connected to the sealing tile through the main pipeline, and the AC sealing oil pump assembly is adapted to provide sealing oil to the sealing tile, and the sealing tile seals the generator under the action of the sealing oil.

[0007] This solution achieves energy savings and power efficiency by activating the AC sealing oil pump during long-term standby of the generator unit to ensure the sealing effect of the engine sealing tiles, while shutting down the lubrication oil pump set and the cooling pump. Furthermore, when the lubrication system experiences leaks, pump malfunctions, or damage to the main generator bearings, requiring maintenance and troubleshooting, the AC sealing oil pump ensures stable operation of the generator's hydrogen and sealing oil systems without the need for hydrogen purging. This eliminates hydrogen leakage, generator oil ingress, and the risk of hydrogen explosion. Moreover, this solution has low construction and modification costs, with full cost recovery within one and a half years. It reduces the probability of hydrogen purging, minimizes the impact on generator insulation, and significantly improves the safety of the hydrogen system.

[0008] In one optional embodiment, the AC sealing oil pump assembly includes: A connecting pipe, wherein the input end of the connecting pipe is adapted to be connected to the oil tank, the output end of the connecting pipe is adapted to be connected to the main pipeline, and the connecting pipe is connected to the sealing tile through the main pipeline; An AC sealing oil pump is installed on the connecting pipeline; the AC sealing oil pump is adapted to drive the lubricating oil in the oil tank toward the sealing tile.

[0009] In one alternative implementation, it further includes: A first check valve is disposed on the main pipeline between the output end of the lubricating oil pump assembly and the output end of the AC sealing oil pump assembly.

[0010] In this scheme, by setting a first check valve, it can be ensured that the AC sealing oil pump will not transmit lubricating oil to the gas turbine or steam turbine.

[0011] In one alternative implementation, it further includes: A DC sealing oil pump, wherein the input end of the DC sealing oil pump is adapted to be connected to the oil tank, and the output end of the DC sealing oil pump is adapted to be connected to the main pipeline between the first one-way valve and the AC sealing oil pump group; the DC sealing oil pump is adapted to drive the lubricating oil in the oil tank to move toward the sealing tile.

[0012] In this solution, a DC sealing oil pump can be set up as a backup pump. When the lubricating oil pump group or the AC sealing oil pump group is damaged, the DC sealing oil pump can supply sealing oil to the sealing tile, thereby increasing the overall fault tolerance of the system.

[0013] In one optional embodiment, the AC sealing oil pump assembly further includes: A first shut-off valve is installed on the connecting pipeline; the first shut-off valve is located upstream of the AC sealing oil pump.

[0014] In one optional embodiment, the AC sealing oil pump assembly further includes: A filter screen is installed on the connecting pipeline between the first shut-off valve and the AC sealing oil pump.

[0015] This solution uses a filter to remove impurities from the pipeline.

[0016] In one optional embodiment, the AC sealing oil pump assembly further includes: A second check valve is installed on the connecting pipeline; the second check valve is located downstream of the AC sealing oil pump.

[0017] In one optional embodiment, the AC sealing oil pump assembly further includes: A pressure gauge is installed on the connecting pipeline between the AC sealing oil pump and the second check valve.

[0018] In one optional embodiment, the AC sealing oil pump assembly further includes: An air cooler is installed on the connecting pipeline between the pressure gauge and the second check valve.

[0019] The second shut-off valve is installed on the connecting pipeline between the air cooler and the second check valve.

[0020] In one alternative implementation, it further includes: An automatic differential pressure regulating valve is installed on the main pipeline between the output end of the AC sealing oil pump unit and the sealing tile. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of the sealing oil supply system of a gas-steam combined cycle unit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an AC sealing oil pump group for a gas-steam combined cycle unit's sealing oil supply system, according to an embodiment of the present invention. Explanation of reference numerals in the attached figures: 1. Gas turbine; 2. Steam turbine; 3. Generator; 4. Lubricating oil pump set; 5. DC sealing oil pump; 6. AC sealing oil pump set; 7. Oil tank; 8. First check valve; 9. Automatic differential pressure regulating valve; 10. Sealing tile; 11. First shut-off valve; 12. Filter screen; 13. Motor; 14. Pressure gauge; 15. Air cooler; 16. Second shut-off valve; 17. Second check valve; 18. AC sealing oil pump; 19. Connecting pipeline; 20. Main pipeline. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] like Figure 1 As shown in the embodiment of the present invention, a sealing oil supply system for a gas-steam combined cycle unit is provided, which is applicable to new power systems.

[0028] The sealing oil supply system of the gas-steam combined cycle unit includes a gas turbine 1, a steam turbine 2, and a generator 3 connected in sequence, and a main pipeline 20 adapted to connect to the gas turbine 1, the steam turbine 2, and the generator 3; it also includes: sealing tiles 10 disposed on both sides of the generator 3; the sealing tiles 10 are adapted to seal the generator 3 and prevent gas leakage from the generator 3; an oil tank 7, internally adapted to store lubricating oil; and a lubricating oil pump set 4, the input end of which is adapted to communicate with the oil tank 7, and the output end of the lubricating oil pump set 4 is connected to the main pipeline 20; the lubricating oil pump set 4 is adapted to connect to both sides of the gas turbine 1 and the steam turbine 2. The two sides of the generator 3 and the two sides of the generator 3 are connected through the main pipeline 20; the lubricating oil pump group 4 is adapted to provide lubricating oil to the bearings of the gas turbine 1, the steam turbine 2 and the generator 3 respectively through the main pipeline 20; the AC sealing oil pump group 6, the input end of the AC sealing oil pump group 6 is adapted to be connected to the oil tank 7, and the output end of the AC sealing oil pump group 6 is adapted to be connected to the main pipeline 20; the AC sealing oil pump group 6 is connected to the sealing tile 10 through the main pipeline 20, and the AC sealing oil pump group 6 is adapted to provide sealing oil to the sealing tile 10, and the sealing tile 10 seals the generator 3 under the action of the sealing oil.

[0029] This solution achieves energy savings and power efficiency by activating the AC sealing oil pump group 6 during long-term standby of the generator unit to ensure the sealing effect of the engine sealing tiles 10, while shutting down the lubricating oil pump group 4 and the cooling pump. Furthermore, when the lubricating oil system experiences leaks, pump malfunctions, or damage to the main generator bearings, requiring shutdown for maintenance and troubleshooting, the AC sealing oil pump 18 ensures stable operation of the generator 3's hydrogen and sealing oil systems without the need for hydrogen purging. This eliminates hydrogen leakage, generator oil ingress, and the risk of hydrogen explosion. Moreover, this solution has low construction and modification costs, with full cost recovery within one and a half years. It reduces the probability of hydrogen purging, minimizes the impact on the generator 3's insulation, and significantly improves the safety of the hydrogen system.

[0030] It should be noted that the working principle of the sealing tile 10 of the generator 3 is to establish a high-pressure oil flow between it and the journal to seal the hydrogen in the generator 3 and prevent the hydrogen from escaping. In this scheme, the connection between the sealing tile 10 and the engine is a conventional connection method.

[0031] It should be noted that the main pipeline 20 is the original oil supply system pipeline. Several branch lines are provided in one direction of the main pipeline 20, with these branch lines located on both sides of the gas turbine 1, steam turbine 2, and generator 3, respectively, providing lubricating oil to the bearings on both sides. A branch line is also provided in the other direction of the main pipeline 20, providing sealing oil to the sealing pad 10. The oil source for the lubricating oil pump group 4, the DC sealing oil pump 5, and the AC sealing oil pump 18 is all taken from the oil tank 7.

[0032] It should be noted that there is no limitation on the number or type of oil pumps in the lubricating oil pump group 4; it can consist of two AC lubricating oil pumps and one DC lubricating oil pump.

[0033] Furthermore, the AC sealing oil pump assembly 6 includes: a connecting pipeline 19 and an AC sealing oil pump 18. The input end of the connecting pipeline 19 is adapted to be connected to the oil tank 7, and the output end is adapted to be connected to the main pipeline 20. The connecting pipeline 19 is connected to the sealing tile 10 through the main pipeline 20. The AC sealing oil pump 18 is disposed on the connecting pipeline 19. The AC sealing oil pump 18 is adapted to drive the lubricating oil in the oil tank 7 to move toward the sealing tile 10.

[0034] It should be noted that the AC sealing oil pump 18 is also connected to a motor 13 suitable for driving the AC sealing oil pump 18.

[0035] It should be noted that the connecting pipe 19 and the main pipe 20 have the same dimensions. In this scheme, in order to ensure the sealing effect of the sealing tile 10, the sealing oil supply pressure is 0.9MPa, the flow rate is 46.1t / h, and the pipe diameter is DN80.

[0036] Furthermore, it also includes a first check valve 8, which is disposed on the main pipeline 20 between the output end of the lubricating oil pump group 4 and the output end of the AC sealing oil pump group 6.

[0037] In this scheme, by setting a first check valve 8, when the lubricating oil pump group 4 is closed and the AC sealing oil pump group 6 is started, it is ensured that the lubricating oil can be supplied to the sealing oil system, and the sealing oil cannot be supplied to the lubricating oil system.

[0038] Furthermore, it also includes a DC sealing oil pump 5, the input end of which is adapted to be connected to the oil tank 7, and the output end of which is adapted to be connected to the main pipeline 20 between the first one-way valve 8 and the AC sealing oil pump group 6; the DC sealing oil pump 5 is adapted to drive the lubricating oil in the oil tank 7 to move toward the sealing tile 10.

[0039] The AC sealing oil pump assembly 6 also includes: The first shut-off valve 11 is installed on the connecting pipeline 19; the first shut-off valve 11 is located upstream of the AC sealing oil pump 18.

[0040] Furthermore, the AC sealing oil pump assembly 6 also includes a filter screen 12, which is disposed on the connecting pipeline 19 between the first shut-off valve 11 and the AC sealing oil pump 18.

[0041] Furthermore, the AC sealing oil pump assembly 6 also includes a second check valve 17, which is disposed on the connecting pipeline 19; the second check valve 17 is disposed downstream of the AC sealing oil pump 18. By providing the second check valve 17, backflow of sealing oil can be prevented from contaminating the oil tank 7.

[0042] Furthermore, the AC sealing oil pump assembly 6 also includes a pressure gauge 14, which is installed on the connecting pipeline 19 between the AC sealing oil pump 18 and the second one-way valve 17.

[0043] Furthermore, the AC sealing oil pump assembly 6 also includes an air cooler 15, which is disposed on the connecting pipeline 19 between the pressure gauge 14 and the second one-way valve 17.

[0044] The second shut-off valve 16 is installed on the connecting pipe 19 between the air cooler 15 and the second one-way valve 17.

[0045] Furthermore, it also includes an automatic differential pressure regulating valve 9, which is installed on the main pipeline 20 between the output end of the AC sealing oil pump group 6 and the sealing tile 10.

[0046] It should be noted that the lubricating oil pump set 4 supplies lubricating oil to the bearings of the gas turbine 1, steam turbine 2 and generator 3 through pipelines; the AC sealing oil pump 18 and DC sealing oil pump 5 supply sealing oil to the sealing tiles 10 of generator 3 through the automatic differential pressure regulating valve 9; the main lubrication pipeline and the main sealing pipeline are connected by a check valve.

[0047] like Figure 2 As shown, the AC sealing oil pump group 6 is arranged in detail as follows: a connecting pipe 19 is connected to the oil tank 7, and a first shut-off valve 11, a filter screen 12, an AC sealing oil pump 18 and a motor 13, a pressure gauge 14, an air cooler 15, a second shut-off valve 16, and a second check valve 17 are arranged sequentially on the connecting pipe 19.

[0048] During normal operation of the gas-steam combined cycle unit, the lubricating oil pump set 4 is in operation, and the DC sealing oil pump 5 is on standby. The lubricating oil is supplied to the bearings of the gas turbine 1, steam turbine 2 and generator 3 through the main pipeline 20, and the sealing oil is supplied to the sealing tiles 10 of generator 3 through the first check valve 8 and the automatic differential pressure regulating valve 9. When the unit is shut down and the turning gear shutdown conditions are met, the AC sealing oil pump 18 is started, and the DC sealing oil pump 5 is on standby. The sealing oil is supplied to the sealing tiles 10 of generator 3 in sequence through the first shut-off valve 11, filter screen 12, AC sealing oil pump 18 and motor 13, pressure gauge 14, air cooler 15, second shut-off valve 16, second check valve 17, and automatic differential pressure regulating valve 9. The lubricating oil pump set 4, jacking oil pump and shut-off cooling pump are shut down, and the lubricating oil system is shut down.

[0049] Based on a conservative estimate (8760 hours per year, with the unit operating for only 1000 hours), the unit is expected to have approximately 3000 hours of downtime for turning gear operation. It should be noted that the equipment consumes the following power per hour: AC oil pump 186.5kW, jacking oil pump 37.3kW, and small shut-off cooling pump 75kW, all of which are shut down simultaneously; the additional AC sealing oil pump 18 is calculated to be approximately 22kW.

[0050] One unit reduces plant power consumption by: 186.5 + 37.3 + 75 - 22 = 276.8 kW.

[0051] Based on the current on-grid electricity price of 0.436 yuan / kWh for gas turbines: 276.8 × 3000 × 0.85 × 0.436 = 307746.24 (yuan).

[0052] Adding a new AC sealing oil pump 18 and supporting pipelines and related equipment costs approximately 400,000 yuan, and the cost can be fully recovered in one and a half years, while greatly improving the safety of the hydrogen system.

[0053] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined in this application.

Claims

1. A sealing oil supply system for a gas-steam combined cycle unit, applicable to new power systems, characterized in that, The sealing oil supply system of the gas-steam combined cycle unit includes a gas turbine (1), a steam turbine (2), and a generator (3) connected in sequence, and a main pipeline (20) suitable for connecting to the gas turbine (1), the steam turbine (2), and the generator (3); it also includes: Sealing tiles (10) are disposed on both sides of the generator (3); the sealing tiles (10) are adapted to seal the generator (3) and prevent gas leakage from the generator (3); The oil tank (7) is suitable for storing lubricating oil. The lubricating oil pump assembly (4) has an input end adapted to be connected to the oil tank (7), and an output end connected to the main pipeline (20); the lubricating oil pump assembly (4) is adapted to be connected to both sides of the gas turbine (1), both sides of the steam turbine (2), and both sides of the generator (3) through the main pipeline (20); the lubricating oil pump assembly (4) is adapted to provide lubricating oil to the bearings of the gas turbine (1), the steam turbine (2), and the generator (3) through the main pipeline (20); An AC sealing oil pump assembly (6) is provided, the input end of which is adapted to be connected to the oil tank (7), and the output end of which is adapted to be connected to the main pipeline (20); the AC sealing oil pump assembly (6) is connected to the sealing tile (10) through the main pipeline (20), and the AC sealing oil pump assembly (6) is adapted to provide sealing oil to the sealing tile (10), and the sealing tile (10) seals the generator (3) under the action of the sealing oil.

2. The sealing oil supply system for a combined gas and steam cycle unit according to claim 1, characterized in that, The AC sealing oil pump assembly (6) includes: A connecting pipe (19) is provided, the input end of which is adapted to be connected to the oil tank (7), the output end of which is adapted to be connected to the main pipeline (20), and the connecting pipe (19) is connected to the sealing tile (10) through the main pipeline (20). An AC sealing oil pump (18) is installed on the connecting pipeline (19); the AC sealing oil pump (18) is adapted to drive the lubricating oil in the oil tank (7) toward the sealing tile (10).

3. The sealing oil supply system for a combined gas and steam cycle unit according to claim 1, characterized in that, Also includes: A first check valve (8) is installed on the main pipeline (20) between the output end of the lubricating oil pump group (4) and the output end of the AC sealing oil pump group (6).

4. The sealing oil supply system for a combined gas and steam cycle unit according to claim 3, characterized in that, Also includes: A DC sealing oil pump (5) is provided, the input end of which is adapted to be connected to the oil tank (7), and the output end of which is adapted to be connected to the main pipeline (20) between the first check valve (8) and the AC sealing oil pump group (6); the DC sealing oil pump (5) is adapted to drive the lubricating oil in the oil tank (7) to move toward the sealing tile (10).

5. The sealing oil supply system for a combined gas and steam cycle unit according to claim 2, characterized in that, The AC sealing oil pump assembly (6) also includes: The first shut-off valve (11) is installed on the connecting pipeline (19); the first shut-off valve (11) is located upstream of the AC sealing oil pump (18).

6. The sealing oil supply system for a combined gas and steam cycle unit according to claim 5, characterized in that, The AC sealing oil pump assembly (6) also includes: A filter screen (12) is installed on the connecting pipe (19) between the first shut-off valve (11) and the AC sealing oil pump (18).

7. The sealing oil supply system for a combined gas and steam cycle unit according to claim 6, characterized in that, The AC sealing oil pump assembly (6) also includes: The second check valve (17) is located on the connecting pipeline (19); the second check valve (17) is located downstream of the AC sealing oil pump (18).

8. The sealing oil supply system for a combined gas and steam cycle unit according to claim 7, characterized in that, The AC sealing oil pump assembly (6) also includes: A pressure gauge (14) is installed on the connecting pipe (19) between the AC sealing oil pump (18) and the second check valve (17).

9. The sealing oil supply system for a combined gas and steam cycle unit according to claim 8, characterized in that, The AC sealing oil pump assembly (6) also includes: An air cooler (15) is installed on the connecting pipe (19) between the pressure gauge (14) and the second check valve (17); The second shut-off valve (16) is installed on the connecting pipe (19) between the air cooler (15) and the second check valve (17).

10. The sealing oil supply system for a combined gas and steam cycle unit according to claim 1, characterized in that, Also includes: An automatic differential pressure regulating valve (9) is installed on the main pipeline (20) between the output end of the AC sealing oil pump group (6) and the sealing tile (10).

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