A steam turbine unit applicable to idling or low-steam-reactive power operation

Abstract

The present invention discloses a steam turbine unit suitable for idling or running with little steam and reactive power, comprising: a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder sequentially connected to a rotating shaft; a steam generator, which is communicated with the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder, and the steam generator is used to supply steam to the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder to drive the rotating shaft to rotate; an auxiliary steam header, and the auxiliary steam header can supply steam to the intermediate-pressure cylinder and the low-pressure cylinder through a steam pipeline. By supplying steam to the intermediate-pressure cylinder and the low-pressure cylinder through the auxiliary steam header, when the steam turbine unit is in a state of running with little steam and reactive power or idling for a long time, at this time, due to the blowing effect, heat is generated at the tail of the cylinder due to the blowing friction loss, resulting in an increase in the temperature at the tail of the cylinder. The steam in the auxiliary steam header is transported to the intermediate-pressure cylinder and the low-pressure cylinder through the steam pipeline, and the steam takes away the frictional heat caused by the blowing of the intermediate-pressure cylinder and the low-pressure cylinder, effectively preventing the tail of the intermediate-pressure cylinder and the low-pressure cylinder from overheating.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation equipment, and particularly relates to a steam turbine unit suitable for idling or low-steam var operation. Background Art

[0002] Generator idling means that the generator rotates at the rated speed without excitation, that is, rotates without load, and can also idle after grid connection. Generally, when the system does not require so much load, or when the system frequency is unstable, it runs without load for a short time according to the dispatching requirements. Idle operation is a standby state of the unit.

[0003] Low-steam var operation generally reduces the unit load to zero at night and during the low-load period of the power grid, but does not disconnect from the power grid, absorbs a small amount of grid power, and makes the unit still in the var state of rotational hot standby at the rated speed.

[0004] Whether the steam turbine unit is in idling or low-steam var operation, it operates at the rated speed of the steam turbine, and the load carried is very low or even zero. Since the rotor is still rotating at high speed, a large amount of heat is generated due to the windage friction loss at the tail of the cylinder, which will cause the temperature at the tail of the cylinder to be too high. Summary of the Invention

[0005] Therefore, in order to overcome the defect that the last stage of the cylinder of the steam turbine unit in the prior art is overheated during idling and low-steam var operation, the present invention provides a steam turbine unit suitable for idling or low-steam var operation and a working method.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A steam turbine unit suitable for idling or low-steam var operation includes: a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence on a rotating shaft; a steam generator, the steam generator is communicated with the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder, and the steam generator is used to supply steam to the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder to drive the rotating shaft to rotate; an auxiliary steam header, the auxiliary steam header supplies steam to the intermediate-pressure cylinder and the low-pressure cylinder through a steam pipeline.

[0008] According to some embodiments of the present invention, the steam turbine unit suitable for idling or low-steam var operation further includes a condenser, the steam outlet end of the steam generator is communicated with the steam inlet end of the high-pressure cylinder through a main steam pipeline, the steam outlet end of the high-pressure cylinder is communicated with the steam inlet end of the intermediate-pressure cylinder through a reheater steam pipeline, the steam outlet end of the intermediate-pressure cylinder is communicated with the steam inlet end of the low-pressure cylinder through an end steam pipeline, and the steam outlet end of the low-pressure cylinder is communicated with the condenser through a condensate pipeline.

[0009] According to some embodiments of the present invention, the reheated steam pipeline section is located inside the steam generator, and a first check valve is provided on the reheated steam pipeline between the steam outlet end of the high-pressure cylinder and the steam generator.

[0010] According to some embodiments of the present invention, a first condensate pipeline is connected between the reheated steam pipeline and the condenser, and a first valve is provided on the first condensate pipeline.

[0011] According to some embodiments of the present invention, the steam turbine unit suitable for idling or low-steam reactive power operation further includes an adjacent unit hot well pipeline connected to the condenser, and the adjacent unit hot well pipeline is used to collect the condensate water in the condenser.

[0012] According to some embodiments of the present invention, the steam turbine unit suitable for idling or low-steam reactive power operation further includes a regenerative heater. The regenerative heater is connected to the intermediate-pressure cylinder through a steam extraction pipeline. One end of the steam extraction pipeline is connected to the sub-final stage position of the intermediate-pressure cylinder, and a second check valve is provided on the steam extraction pipeline.

[0013] According to some embodiments of the present invention, the steam pipeline includes a first steam pipeline. The first steam pipeline is connected to the steam extraction pipeline, and the connection position between the first steam pipeline and the steam extraction pipeline is located between the second check valve and the intermediate-pressure cylinder. A second valve is provided on the first steam pipeline, and a third valve is provided between the first steam pipeline and the second check valve.

[0014] According to some embodiments of the present invention, the steam pipeline further includes a second steam pipeline. The second steam pipeline is connected to the exhaust steam pipeline, and a fourth valve is provided on the second steam pipeline.

[0015] According to some embodiments of the present invention, the rotating shaft is connected to a generator. The generator is electrically connected to the power grid. The generator transmits electric energy to the power grid during the power generation operation state and consumes the electric energy of the power grid during the idling or low-steam reactive power operation state.

[0016] According to some embodiments of the present invention, when the steam turbine unit is a 300MW-class steam turbine unit, the steam supply amount of the auxiliary steam header to the intermediate-pressure cylinder is 1 - 3t / h, and the steam supply amount to the low-pressure cylinder is about 18 - 22t / h; when the steam turbine unit is a 600MW-class steam turbine unit, the steam supply amount of the auxiliary steam header to the intermediate-pressure cylinder is 3 - 5t / h, and the steam supply amount to the low-pressure cylinder is about 36 - 44t / h.

[0017] The technical solution of the present invention has the following advantages:

[0018] 1. The steam turbine unit provided by the present invention is suitable for idling or less steam and reactive operation. The high pressure cylinder, the medium pressure cylinder and the low pressure cylinder are sequentially distributed along the central axis direction of the rotating shaft. The steam generator is used to generate steam. The steam generator is connected with the high pressure cylinder, the medium pressure cylinder and the low pressure cylinder. The steam enters the high pressure cylinder, the medium pressure cylinder and the low pressure cylinder in turn. The steam drives the blades of the high pressure cylinder, the medium pressure cylinder and the low pressure cylinder to rotate, thereby driving the rotating shaft to rotate, that is, the steam heat energy generated by the steam generator is converted into mechanical energy, which rotates to drive the generator to operate, and then converts the mechanical energy into electrical energy. Steam is supplied to the medium pressure cylinder and the low pressure cylinder through the auxiliary steam manifold. When the steam turbine unit is in the state of less steam and reactive operation and idling for a long time, due to the blast effect, the tail of the cylinder generates a lot of heat due to the blast friction loss, which causes the temperature of the tail of the cylinder to rise, thereby affecting the service life and working quality of the steam turbine unit. The steam in the auxiliary steam manifold is transported to the intermediate pressure cylinder and the low pressure cylinder through the steam pipeline. The steam takes away the friction heat caused by the blowing of the intermediate pressure cylinder and the low pressure cylinder, effectively preventing the tail of the intermediate pressure cylinder and the low pressure cylinder from overheating.

[0019] 2. The steam turbine unit provided by the present invention is suitable for idling or low-steam reactive operation. When the steam generator stops working, steam can also be supplied through the auxiliary steam header, which not only solves the overtemperature problem of the intermediate pressure cylinder and the low pressure cylinder, but also can realize the hot standby state of the steam turbine unit without stopping the furnace, thereby improving the flexibility of the steam turbine unit.

[0020] 3. The steam turbine unit provided by the present invention is suitable for idling or low-steam reactive operation. When the steam turbine unit is in a state of low-steam reactive operation and idling for a long time, the generator connected to the rotating shaft is connected in parallel with the power grid, and the steam turbine unit is driven to rotate by the power of the power grid. The generator is changed to an electric motor mode, supplying a large amount of reactive power to the power grid, thereby solving the voltage increase caused by the lack of reactive power during low electricity consumption and maintaining stable operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of a steam turbine unit operating system provided in some embodiments of the present invention.

[0023] Description of the reference numerals: 1. Rotating shaft; 2. High-pressure cylinder; 3. Intermediate-pressure cylinder; 4. Low-pressure cylinder; 5. Steam generator; 6. Auxiliary steam header; 7. Condenser; 8. Generator; 9. Main steam pipeline; 10. Reheat steam pipeline; 11. Exhaust steam pipeline; 12. First check valve; 13. Second check valve; 14. First valve; 15. Second valve; 16. Third valve; 17. Fourth valve; 18. First condensate pipeline; 19. First steam pipeline; 20. Second steam pipeline; 21. Pipeline of the adjacent unit's hot well; 22. Feedwater heater. Detailed implementation manners

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the connection inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0027] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Refer to Figure 1As shown in the figure, a steam turbine unit applicable to idling or low-steam reactive operation proposed by the present invention includes: a high-pressure cylinder 2, an intermediate-pressure cylinder 3, and a low-pressure cylinder 4 sequentially connected to a rotating shaft 1; a steam generator 5, which is connected to the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4, and the steam generator 5 is used to supply steam to the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 to drive the rotation of the rotating shaft 1; an auxiliary steam header 6, and the auxiliary steam header 6 supplies steam to the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 through a steam pipeline.

[0029] Specifically, the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 are sequentially distributed along the central axis direction of the rotating shaft 1. The steam generator 5 is used to generate steam. The steam generator 5 is connected to the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4. Steam sequentially enters the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4. The steam drives the blades of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 to rotate, thereby driving the rotation of the rotating shaft 1. That is, the thermal energy of the steam generated by the steam generator 5 is converted into mechanical energy, and the rotation drives the generator 8 to operate, converting the mechanical energy into electrical energy. When the steam turbine unit is in idling or low-steam reactive operation, at this time, due to the blowing effect, a large amount of heat is generated due to the blowing friction loss at the tail of the cylinder, resulting in an increase in the temperature at the tail of the cylinder, which in turn affects the service life and working quality of the steam turbine unit.

[0030] Specifically, the steam generator 5 includes an electric heating steam generator 5, a gas steam generator 5, a fuel steam generator 5, and a biomass steam generator 5. The type of the steam generator 5 is not limited in the present invention.

[0031] Steam is supplied to the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 through the auxiliary steam header 6. When the steam turbine unit is in a state of long-term low-steam reactive operation and idling, at this time, heat is generated by friction at the tail of the cylinder. The steam in the auxiliary steam header 6 is transported to the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 through the steam pipeline. The steam takes away the frictional heat caused by blowing in the intermediate-pressure cylinder 3 and the low-pressure cylinder 4, effectively preventing overheating at the tails of the intermediate-pressure cylinder 3 and the low-pressure cylinder 4; in addition, when the steam generator 5 stops working, steam can also be supplied through the auxiliary steam header 6, ensuring the normal operation of the steam turbine unit and improving the flexibility of the thermal turbine unit.

[0032] In some embodiments of the present invention, the steam turbine unit applicable to idling or low-steam reactive operation further includes a condenser 7. The steam outlet end of the steam generator 5 is connected to the steam inlet end of the high-pressure cylinder 2 through a main steam pipeline 9. The steam exhaust port end of the high-pressure cylinder 2 is connected to the steam inlet end of the intermediate-pressure cylinder 3 through a reheating steam pipeline 10. The steam outlet end of the intermediate-pressure cylinder 3 is connected to the steam inlet end of the low-pressure cylinder 4 through a final steam pipeline 11. The steam outlet end of the low-pressure cylinder 4 is connected to the condenser 7 through a condensate pipeline.

[0033] Specifically, as a heat exchanger, the condenser 7 is connected to the steam outlet end of the low-pressure cylinder 4 through a condensing pipeline. The condenser 7 forms and maintains a vacuum at the steam outlet end of the low-pressure cylinder 4, enabling the steam to flow successively through the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 from the steam generator 5, driving the blades in the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 to rotate, thereby driving the rotation of the rotating shaft 1. The steam condenses into a liquid in the condenser 7, and the condensed liquid is recycled for reuse, saving resources and reducing costs.

[0034] It can be understood that the steam outlet end of the high-pressure cylinder 2 is connected to the steam inlet end of the intermediate-pressure cylinder 3 through a reheating steam pipeline 10. Since the steam will lose heat and cause a decrease in energy when passing through the high-pressure cylinder 2, the reheating steam pipeline 10 reheats the steam to avoid excessive heat loss during the process of the steam flowing from the high-pressure cylinder 2 to the intermediate-pressure cylinder 3, which affects the working efficiency.

[0035] In some embodiments of the present invention, a part of the reheating steam pipeline 10 is located inside the steam generator 5, and a first check valve 12 is provided on the reheating steam pipeline 10 between the steam outlet end of the high-pressure cylinder 2 and the steam generator 5.

[0036] Specifically, a part of the reheating steam pipeline 10 is provided inside the steam generator 5. The reheating steam pipeline 10 is divided into a cold reheat section and a hot reheat section with the steam generator 5 as a node. Among them, the reheating steam pipeline 10 from the steam outlet end of the high-pressure cylinder 2 to the steam generator 5 is the cold reheat section, and the reheating steam pipeline 10 from the steam generator 5 to the steam inlet end of the intermediate-pressure cylinder 3 is the hot reheat section. The first check valve 12 is arranged in the cold reheat section, that is, on the reheating steam pipeline 10 between the steam outlet end of the high-pressure cylinder 2 and the steam generator 5. The first check valve 12 prevents the steam entering the steam generator 5 from the cold reheat section from flowing back to the tail of the high-pressure cylinder 2 after heating, which affects the operation of the steam turbine unit.

[0037] In some embodiments of the present invention, a first condensing pipeline 18 is connected between the reheating steam pipeline 10 and the condenser 7, and a first valve 14 is provided on the first condensing pipeline 18.

[0038] Specifically, when the steam turbine is in an idling or low-steam and reactive-power operation state, since the high-pressure cylinder 2 is small in volume and generates less heat due to air blowing, it can operate without steam inlet and maintain the temperature of the high-pressure cylinder 2 by air-blowing heat generation. At this time, the first valve 14 on the first condensing pipeline 18 is opened, which not only avoids a small amount of remaining steam in the cylinder but also facilitates the heat dissipation of the high-pressure cylinder 2 and prevents the tail of the high-pressure cylinder 2 from overheating.

[0039] In some embodiments of the present invention, the steam turbine unit suitable for idling or low-steam and reactive-power operation further includes a neighboring unit hot well pipeline 21 connected to the condenser 7, and the neighboring unit hot well pipeline 21 is used to collect the condensed water in the condenser 7.

[0040] Specifically, the steam is cooled and condensed by the condenser 7, and the condensed liquid is transported to the steam generator 5 through the pipeline of the adjacent unit hot well 21 and reheated to form steam. This steam can be transported to the auxiliary steam header 6 for reuse, supplying steam to the intermediate pressure cylinder 3 and the low pressure cylinder 4, forming a circulation system. Such a setting is conducive to saving resources and reducing costs.

[0041] In some embodiments of the present invention, the steam turbine unit applicable to idling or low-steam reactive operation further includes a regenerative heater 22. The regenerative heater 22 is connected to the intermediate pressure cylinder 3 through a steam extraction pipeline. One end of the steam extraction pipeline is connected to the sub-final stage position of the intermediate pressure cylinder 3, and a second check valve 13 is provided on the steam extraction pipeline.

[0042] Specifically, the regenerative heater 22 uses the steam extracted from the intermediate stage of the steam turbine to heat the condensate of the condenser 7 and the feed water of the steam generator 5. The purpose is to increase the feed water temperature of the steam generator 5, thereby improving the thermal economy of the unit. The heating steam of the regenerative heater 22 is the extraction steam that has done work in the steam turbine and is extracted from the intermediate stage of the steam turbine. The steam has converted part of its energy into mechanical work in the steam turbine, and releases heat and condenses into water in the heater, transferring its superheat heat and latent heat of vaporization to the heated condensate or feed water. Therefore, there is no cold source loss during the work process of the regenerative extraction steam. Hence, the economic efficiency of using this regenerative heating method is significantly improved compared to directly sending the condensate of the condenser 7 into the boiler for heating.

[0043] It can be understood that the purpose of using steam to heat the feed water of the steam generator 5 is to reduce cold source loss. A certain amount of steam no longer releases heat to the air in the condenser 7 after doing part of the work, that is, the heat of the steam is not taken away by the air, making the heat of the steam fully utilized, the heat consumption rate decreases. At the same time, since the steam that has done part of the work in the steam turbine is used to heat the feed water, the feed water temperature is increased, and the heat transfer temperature difference of the heating surface of the steam generator 5 is reduced, thereby reducing the irreversible loss during the feed water heating process, and the heat absorption in the steam generator 5 also decreases accordingly. The heat enthalpy of this part of the extraction steam is fully utilized and not carried away by the circulating water cooling.

[0044] After adopting the regenerative heater 22, the total steam consumption of the steam turbine unit increases, while the heat consumption and coal consumption of the steam turbine unit decrease. The steam consumption rate increases because the work done by each kilogram of steam entering the steam turbine decreases, while the decrease in heat consumption and coal consumption is due to the increase in feed water temperature caused by the reduction of cold source loss. Therefore, after adopting the regenerative heater 22, the thermal economy of the steam turbine unit is improved. In addition, by adopting the regenerative heating system, since the feed water temperature is increased, the thermal stress generated by the excessive heat transfer temperature difference of the heating surface of the steam generator 5 can be reduced, thereby improving the reliability of the equipment.

[0045] In some embodiments of the present invention, the steam pipeline includes a first steam pipeline 19, the first steam pipeline 19 is communicated with the extraction pipeline, the position where the first steam pipeline 19 and the extraction pipeline are communicated is located between the second check valve 13 and the intermediate pressure cylinder 3, a second valve 15 is provided on the first steam pipeline 19, and a third valve 16 is provided between the first steam pipeline 19 and the second check valve 13.

[0046] In some embodiments of the present invention, the steam pipeline further includes a second steam pipeline 20, the second steam pipeline 20 is communicated with the exhaust steam pipeline 11, and a fourth valve 17 is provided on the second steam pipeline 20.

[0047] Specifically, the steam pipeline includes a first steam pipeline 19 and a second steam pipeline 20. The auxiliary steam header 6 supplies steam to the intermediate pressure cylinder 3 through the first steam pipeline 19 and supplies steam to the low pressure cylinder 4 through the second steam pipeline 20. Since the volume of the low pressure cylinder 4 is large, when only the first steam pipeline 19 is used to supply steam to the intermediate pressure cylinder 3, the temperature reduction effect is not good. The first steam pipeline 19 is communicated with the extraction pipeline, and the steam of the auxiliary steam header 6 enters the extraction pipeline through the first steam pipeline 19, and then enters the second last stage position of the intermediate pressure cylinder 3, taking away the heat generated by friction at the tail of the intermediate pressure cylinder 3, avoiding overheating at the tail of the intermediate pressure cylinder 3, and at the same time providing part of the steam for the low pressure cylinder 4. The steam of the auxiliary steam header 6 enters the low pressure cylinder 4 through the second steam pipeline 20 to cool the tail of the low pressure cylinder 4 and avoid overheating of the tail of the low pressure cylinder 4 caused by air blowing.

[0048] It can be understood that when the steam turbine unit is in an idle or low-steam reactive operation state, since the volume of the high pressure cylinder 2 is small and the heat generated by air blowing is less, steam can be not supplied, and the temperature of the high pressure cylinder 2 is maintained by the heat generated by air blowing. First, the first condenser pipeline 18 is opened to avoid a small amount of remaining steam in the cylinder and avoid overheating at the tail of the high pressure cylinder 2; secondly, the second valve 15 is opened to make the steam in the auxiliary steam header 6 flow towards the intermediate pressure cylinder 3, and the third valve 16 is closed to avoid steam loss so that the steam can completely enter the second last stage position of the intermediate pressure cylinder 3; finally, the fourth valve 17 is opened to make the steam in the auxiliary steam header 6 flow towards the tail of the low pressure cylinder 4.

[0049] It should be noted that since the blades in the second half of the intermediate pressure cylinder 3 are long and the air blowing friction is relatively serious, heat needs to be taken away by the steam flow. Therefore, heat is supplied to the second last stage of the intermediate pressure cylinder 3 to avoid overheating of the intermediate pressure cylinder 3. The low pressure cylinder 4 has a large volume, long blades, and a low temperature-bearing grade of the metal material. At high speeds, the heat generated by air blowing is serious and steam needs to be introduced to take away the heat. Therefore, the second steam pipeline 20 is communicated with the exhaust steam pipeline 11 to introduce steam into the low pressure cylinder 4 to avoid overheating of the low pressure cylinder 4.

[0050] In some embodiments of the present invention, a generator 8 is connected to the rotating shaft 1, and the generator 8 is electrically connected to the power grid. When the generator 8 is in the power generation operation state, it delivers electric energy to the power grid, and when it is in the idling or low-steam reactive power operation state, it consumes the electric energy of the power grid.

[0051] Specifically, when the steam turbine unit is in the idling or low-steam reactive power operation state, the generator 8 connected to the rotating shaft 1 is connected in parallel with the power grid, and the rotating shaft 1 of the steam turbine unit is driven to rotate by the power grid power. At this time, the generator 8 is in the motor mode and can supply a large amount of reactive power to the power grid, solving the voltage increase caused by the lack of reactive power during the low-power consumption period of the power grid and maintaining the stable operation of the power grid.

[0052] In some embodiments of the present invention, when the steam turbine unit is a 300 MW-class steam turbine unit, the amount of steam supplied by the auxiliary steam header 6 to the intermediate pressure cylinder 3 is 1 - 3 t / h, and the amount of steam supplied to the low pressure cylinder 4 is 18 - 22 t / h; when the steam turbine unit is a 600 MW-class steam turbine unit, the amount of steam supplied by the auxiliary steam header 6 to the intermediate pressure cylinder 3 is 3 - 5 t / h, and the amount of steam supplied to the low pressure cylinder 4 is 36 - 44 t / h.

[0053] Specifically, since the low pressure cylinder 4 has a large volume and long blades, more steam is required. In some embodiments of the present invention, when the steam turbine unit is a 300 MW-class steam turbine unit, the amount of steam supplied to the low pressure cylinder 4 is 20 t / h, and when the steam turbine unit is a 600 MW-class steam turbine unit, the amount of steam supplied to the low pressure cylinder 4 is 40 t / h. In addition, according to the values of the steam supply amounts to the intermediate pressure cylinder 3 and the low pressure cylinder 4, it can be obtained that the pipe diameter of the second steam pipeline 20 is larger than that of the first steam pipeline 19.

[0054] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A steam turbine unit applicable to idle running or running with little steam and reactive power, characterized in that, Comprising: A high-pressure cylinder (2), an intermediate-pressure cylinder (3), and a low-pressure cylinder (4) sequentially connected to a rotating shaft (1); A steam generator (5), which is communicated with the high-pressure cylinder (2), the intermediate-pressure cylinder (3), and the low-pressure cylinder (4), and the steam generator (5) is used to supply steam to the high-pressure cylinder (2), the intermediate-pressure cylinder (3), and the low-pressure cylinder (4) to drive the rotating shaft (1) to rotate; An auxiliary steam header (6), and the auxiliary steam header (6) supplies steam to the intermediate-pressure cylinder (3) and the low-pressure cylinder (4) through a steam pipeline; The rotating shaft (1) is connected with a generator (8), the generator (8) is electrically connected to the power grid, and the generator (8) transmits electric energy to the power grid during the power generation operation state and consumes the electric energy of the power grid during the idling or low-steam reactive operation state; Steam is supplied to the intermediate-pressure cylinder (3) and the low-pressure cylinder (4) through the auxiliary steam header (6). When the steam turbine unit is in a long-term low-steam reactive operation and idling state, friction generates heat at the tail of the cylinder. The steam in the auxiliary steam header (6) is transported to the intermediate-pressure cylinder (3) and the low-pressure cylinder (4) through a steam pipeline, and the steam takes away the frictional heat caused by the drum wind of the intermediate-pressure cylinder (3) and the low-pressure cylinder (4), effectively preventing the tail of the intermediate-pressure cylinder (3) and the low-pressure cylinder (4) from overheating; when the steam generator (5) stops working, steam can also be supplied through the auxiliary steam header (6), ensuring the normal operation of the steam turbine unit and improving the flexibility of the steam turbine unit.

2. The steam turbine unit applicable to idling or low-steam-reactive power operation according to claim 1, characterized in that, It further includes a condenser (7). The steam outlet end of the steam generator (5) is communicated with the steam inlet end of the high-pressure cylinder (2) through a main steam pipeline (9). The steam outlet end of the high-pressure cylinder (2) is communicated with the steam inlet end of the intermediate-pressure cylinder (3) through a reheating steam pipeline (10). The steam outlet end of the intermediate-pressure cylinder (3) is communicated with the steam inlet end of the low-pressure cylinder (4) through a final steam pipeline (11). The steam outlet end of the low-pressure cylinder (4) is communicated with the condenser (7) through a condensate pipeline.

3. The steam turbine unit applicable to idling or low-steam-reactive power operation according to claim 2, wherein A part of the reheating steam pipeline (10) is located inside the steam generator (5), and a first check valve (12) is provided on the reheating steam pipeline (10) between the steam outlet end of the high-pressure cylinder (2) and the steam generator (5).

4. The steam turbine unit applicable to idle or low-steam-reactive power operation according to claim 3, characterized in that, A first condensate pipeline (18) is communicated between the reheating steam pipeline (10) and the condenser (7), and a first valve (14) is provided on the first condensate pipeline (18).

5. The steam turbine unit applicable to idling or low-steam-reactive power operation according to claim 2, wherein It further includes a hot well pipeline of the adjacent unit (21) connected to the condenser (7), and the hot well pipeline of the adjacent unit (21) is used to collect the condensate water in the condenser (7).

6. The steam turbine unit applicable to idling or low-steam-reactive power operation according to claim 2, characterized in that, It further includes a regenerative heater (22), and the regenerative heater (22) is communicated with the intermediate-pressure cylinder (3) through a steam extraction pipeline. One end of the steam extraction pipeline is connected to the sub-final stage position of the intermediate-pressure cylinder (3), and a second check valve (13) is provided on the steam extraction pipeline.

7. The steam turbine unit applicable to idling or low-steam-reactive power operation according to claim 6, characterized in that, The steam pipeline includes a first steam pipeline (19), the first steam pipeline (19) is communicated with the extraction steam pipeline, the position where the first steam pipeline (19) and the extraction steam pipeline are communicated is between the second check valve (13) and the intermediate pressure cylinder (3), a second valve (15) is provided on the first steam pipeline (19), and a third valve (16) is provided between the first steam pipeline (19) and the second check valve (13).

8. The steam turbine unit applicable to idle or low-steam-reactive operation according to claim 7, characterized in that, The steam pipeline further includes a second steam pipeline (20), the second steam pipeline (20) is communicated with the exhaust steam pipeline (11), and a fourth valve (17) is provided on the second steam pipeline (20).

9. The steam turbine unit applicable to idle or low-steam-reactive power operation according to claim 1, characterized in that, When the steam turbine unit is a 300MW-class steam turbine unit, the steam supply amount of the auxiliary steam header (6) to the intermediate pressure cylinder (3) is 1 - 3t / h, and the steam supply amount to the low pressure cylinder (4) is 18 - 22t / h; when the steam turbine unit is a 600MW-class steam turbine unit, the steam supply amount of the auxiliary steam header (6) to the intermediate pressure cylinder (3) is 3 - 5t / h, and the steam supply amount to the low pressure cylinder (4) is 36 - 44t / h.

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