Backpressure steam turbine system with small steam exhaust amount

Abstract

The utility model relates to a backpressure steam turbine system with small steam exhaust amount, which comprises a main steam pipeline which is connected with a first shunting pipeline and a second shunting pipeline in parallel, and the first shunting pipeline is connected with a medium-pressure steam-distributing cylinder; the second shunting pipeline is connected to the high-medium pressure cylinder; the high-medium-pressure cylinder is connected with a third shunting pipeline and a fourth shunting pipeline in parallel; the third shunting pipeline is connected to an air inlet of the low-pressure cylinder; the low-pressure cylinder and the high-medium-pressure cylinder are oppositely arranged; the low-pressure cylinder further comprises a fifth flow dividing pipe and a sixth flow dividing pipe, the fifth flow dividing pipe is connected to the first high-pressure heater, and the sixth flow dividing pipe is connected with a deaerator and a low-pressure steam dividing cylinder in parallel. And the fourth shunting pipe is connected with a second high-pressure heater and a medium-pressure steam-distributing cylinder in parallel. By means of the backpressure turbine system with the small steam exhaust amount, the problems that when the low-pressure thermal load of an existing turbine is low, operation of the turbine is limited, stable and continuous operation cannot be achieved, potential safety hazards exist, and economic benefits are reduced due to shutdown of the turbine can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to steam turbine technical field, concretely relates to a back pressure steam turbine system of small exhaust capacity. BACKGROUND

[0002] The existing steam turbine generally adopts integral design, and the high-pressure cylinder and the low-pressure cylinder are directly communicated, the low-pressure cylinder exhaust mode is used to supply steam for low-pressure users under normal circumstances, and the main steam temperature reduction and pressure reduction are used as a standby steam supply mode. When the low-pressure heat load is low, the steam turbine exhaust capacity is often lower than the minimum exhaust capacity required for safe continuous operation, so that the steam turbine operation is limited, and stable continuous operation cannot be realized. In order to ensure the safety of the unit, the inlet steam temperature usually needs to be reduced, but the exhaust temperature is still higher than the specified value, and there is still a safety hazard. In order to ensure safety, the steam turbine needs to be shut down, but after the steam turbine is shut down, the main steam temperature reduction and pressure reduction mode can only be used to supply steam for low-pressure users, at this time the boiler is normally operated, high-priced electricity needs to be purchased from the external power grid for plant power, and the economic benefit is reduced.

[0003] Therefore, the prior art has defects and needs to be improved and developed. UTILITY MODEL CONTENT

[0004] The utility model embodiment provides a back pressure steam turbine system of small exhaust capacity, which is used for solving the problems in the prior art that the existing steam turbine generally adopts integral design, the high-pressure cylinder and the low-pressure cylinder are directly communicated, the low-pressure cylinder exhaust mode is used to supply steam for low-pressure users under normal circumstances, the main steam temperature reduction and pressure reduction are used as a standby steam supply mode. When the low-pressure heat load is low, the steam turbine exhaust capacity is often lower than the minimum exhaust capacity required for safe continuous operation, so that the steam turbine operation is limited, and stable continuous operation cannot be realized. In order to ensure the safety of the unit, the inlet steam temperature usually needs to be reduced, but the exhaust temperature is still higher than the specified value, and there is still a safety hazard. In order to ensure safety, the steam turbine needs to be shut down, but after the steam turbine is shut down, the main steam temperature reduction and pressure reduction mode can only be used to supply steam for low-pressure users, at this time the boiler is normally operated, high-priced electricity needs to be purchased from the external power grid for plant power, and the economic benefit is reduced.

[0005] An embodiment of the utility model provides a back-pressure steam turbine system with a small exhaust steam volume, which includes a main steam pipeline. The outlet of the main steam pipeline is connected in parallel with a first shunt pipeline and a second shunt pipeline. The outlet of the first shunt pipeline is connected to an intermediate-pressure steam header, which is used to transfer steam to intermediate-pressure heat users. A medium-pressure desuperheating and pressure-reducing device is connected in series between the first shunt pipeline and the intermediate-pressure steam header. The outlet of the second shunt pipeline is connected to a high-pressure and intermediate-pressure cylinder; the outlet of the high-pressure and intermediate-pressure cylinder is connected in parallel with a third shunt pipeline and a fourth shunt pipeline, and the third shunt pipeline is connected to the inlet of a low-pressure cylinder; the low-pressure cylinder and the high-pressure and intermediate-pressure cylinder are arranged head-to-head; the low-pressure cylinder further includes a fifth shunt pipe and a sixth shunt pipe. The outlet of the fifth shunt pipe is connected to a first high-pressure heater, and the outlet of the sixth shunt pipe is connected in parallel with a deaerator and a low-pressure steam header, which is used to transfer steam to low-pressure heat users; the outlet of the fourth shunt pipe is connected in parallel with a second high-pressure heater and the intermediate-pressure steam header.

[0006] Further, define the height of the moving blades of a conventional low-pressure cylinder as A, and the moving blades of the low-pressure cylinder as B, where B < A, and A and B are numbers greater than 0.

[0007] Further, a valve is connected in series between the third shunt pipeline and the inlet of the low-pressure cylinder. When the steam of the high-pressure and intermediate-pressure cylinder enters the low-pressure cylinder, the opening degree of the valve is adjusted to control the steam flow rate entering the low-pressure cylinder.

[0008] Further, the outlet of the fourth shunt pipe is also connected in parallel with the low-pressure steam header, and a low-pressure desuperheating and pressure-reducing device is connected in series between the low-pressure steam header and the sixth shunt pipe.

[0009] Beneficial effects:

[0010] As can be seen from the above technical solution, this utility model provides a small-displacement back-pressure steam turbine system. By modifying the low-pressure cylinder and limiting the height of the moving blades, the height of the moving blades is reduced compared to existing designs, thus reducing the flow area of ​​the low-pressure cylinder and lowering the minimum required discharge volume for safe continuous operation. This allows for safe and stable continuous operation even under low-pressure heat load conditions. This design effectively alleviates the problem of insufficient discharge volume in the original design under low-pressure heat load conditions, ensuring that no safety hazards are caused by insufficient discharge volume of the low-pressure cylinder during operation. A regulating valve is installed in series between the third branch pipe and the low-pressure cylinder inlet, simultaneously achieving precise control of the medium-pressure heat load. The regulating valve can adjust the steam distribution in real time according to changes in the medium-pressure heat load, so that the medium- and low-pressure steam supply ratio is dynamically balanced, ensuring that the low-pressure system can still meet its heat load requirements when the medium-pressure load fluctuates. By connecting a low-pressure steam distribution cylinder and a low-pressure desuperheater and pressure reducer in parallel at the outlet of the fourth branch pipe, a supplementary steam supply to low-pressure heat users is provided, offering necessary supplementary regulation functions when the low heat load increases significantly. Under normal circumstances, steam is supplied to low-pressure heat loads via exhaust from the low-pressure cylinder. The exhaust design of the low-pressure cylinder incorporates a margin; only when the low heat load increases significantly is a cryogenic desuperheater used to supplement heat supply to low-pressure users. This helps reduce the cost of cryogenic steam supply while ensuring that heat users receive suitable steam parameters, improving the overall system's economy and operating efficiency. By designing the intermediate and high-pressure cylinders head-to-head with the low-pressure cylinders, they can be arranged within the same outer cylinder, achieving physical isolation while sharing the same rotor. This achieves a layout similar to two steam turbines. This scheme modifies only the low-pressure cylinder without changing the original flow area of ​​the intermediate and high-pressure cylinders, avoiding excessive alterations to the overall turbine structure, reducing modification costs, shortening construction time, and ensuring that the modified system still meets the original compliance requirements. It has high application value.

[0011] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0012] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0013] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0014] Figure 1 This is a schematic diagram of the connection structure of a small-displacement back-pressure steam turbine system in an embodiment of this application.

[0015] Explanation of icon numbers:

[0016] 1. Main steam pipeline; 2. First branch pipeline; 3. Second branch pipeline; 4. Intermediate-pressure steam cylinder; 5. Intermediate-pressure desuperheater and pressure reducer; 6. High- and intermediate-pressure cylinder; 7. Third branch pipeline; 701. Valve; 8. Fourth branch pipeline; 9. Low-pressure cylinder; 10. Fifth branch pipe; 11. Sixth branch pipe; 12. First high-pressure heater; 13. Deaerator; 14. Low-pressure steam cylinder; 15. Second high-pressure heater; 16. Low-pressure desuperheater and pressure reducer. Detailed Implementation

[0017] 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0018] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0019] In existing technologies, steam turbines generally adopt an integrated design, with their high-pressure, intermediate-pressure, and low-pressure cylinders directly connected. Under normal circumstances, steam is supplied to low-pressure users via the low-pressure cylinder exhaust method, while the main steam desuperheating and pressure reduction method serves as a backup steam supply method. When the low-pressure heat load is low, the steam turbine exhaust volume is often lower than the minimum exhaust volume required for safe continuous operation, thus limiting the turbine's operation and preventing stable continuous operation. To ensure unit safety, the inlet steam temperature usually needs to be reduced, but the exhaust temperature is still higher than the specified value, still posing a safety hazard. To ensure safety, the turbine needs to be shut down. After the turbine is shut down, steam can only be supplied to low-pressure users via the main steam desuperheating and pressure reduction method. At this time, the boiler is operating normally, requiring the purchase of expensive electricity from the external power grid for plant use, reducing economic efficiency.

[0020] Therefore, this utility model embodiment provides a small-displacement back-pressure steam turbine system, referring to... Figure 1 The system includes a main steam pipe 1, with a first branch pipe 2 and a second branch pipe 3 connected in parallel to the outlet of the main steam pipe 1. The outlet of the first branch pipe 2 is connected to an intermediate-pressure steam distribution cylinder 4, which is used to transfer steam to intermediate-pressure heat users. An intermediate-pressure desuperheater and pressure reducer 5 is connected in series between the first branch pipe 2 and the intermediate-pressure steam distribution cylinder 4. The outlet of the second branch pipe 3 is connected to an intermediate-high-pressure cylinder 6. The outlet of the intermediate-high-pressure cylinder 6 is connected in parallel to a third branch pipe 7 and a fourth branch pipe 8. The third branch pipe 7 is connected to a low-pressure cylinder. The air inlet of cylinder 9; low-pressure cylinder 9 and high-medium-pressure cylinder 6 are arranged opposite each other, and the moving blades of low-pressure cylinder 9 and high-medium-pressure cylinder 6 are driven by the same rotor; low-pressure cylinder 9 also includes a fifth branch pipe 10 and a sixth branch pipe 11, the air outlet of the fifth branch pipe 10 is connected to the first high-pressure heater 12, the air outlet of the sixth branch pipe 11 is connected in parallel to the deaerator 13 and the low-pressure steam separator 14, the low-pressure steam separator 14 is used to transfer steam to the low-pressure heat user; the air outlet of the fourth branch pipe is connected in parallel to the second high-pressure heater 15 and the medium-pressure steam separator 4.

[0021] The main steam is fed to the intermediate-pressure steam distribution cylinder 4 and the intermediate-high-pressure cylinder 6 via a first diversion pipe 2 and a second diversion pipe 3 connected in parallel through the outlet of the main steam pipe 1. Under normal circumstances, the main steam is sent to the intermediate-high-pressure cylinder 6; it is only sent to the intermediate-pressure steam distribution cylinder 4 when the turbine is not running. An intermediate-pressure desuperheater and pressure reducer 5 is connected in series between the intermediate-pressure steam distribution cylinder 4 and the first diversion pipe 2. Its function is to adjust the temperature and pressure of the steam during transmission to meet the requirements of the intermediate-pressure heat user. The intermediate-high-pressure cylinder 6 is further diverted by a third diversion pipe 7 and a fourth diversion pipe 8. The third diversion pipe 7 is directly connected to the inlet of the low-pressure cylinder 9, while the low-pressure cylinder 9 is rotatably connected to the intermediate-high-pressure cylinder 6 via the same rotor. The intermediate-high-pressure cylinder 6 and the low-pressure cylinder 9 are arranged opposite each other, with rotor seals installed at the opposite end. This design utilizes the principle of physical isolation but shared transmission to achieve independent operation of the high and low-pressure cylinders within the same outer cylinder, thus meeting the requirement of safe and continuous operation under low exhaust volume.

[0022] The intermediate and high-pressure cylinder 6 and the low-pressure cylinder 9 are arranged opposite each other and separated, with the exhaust steam from the intermediate and high-pressure cylinder 6 entering the low-pressure cylinder 9. The intermediate and high-pressure cylinder 6 and the low-pressure cylinder 9 can be regarded as being arranged in the same outer cylinder. The opposite arrangement reduces axial thrust and is beneficial to the safe operation of the steam turbine.

[0023] In some embodiments, the height of the moving blades of the conventional low-pressure cylinder is defined as A, and the height of the moving blades of the low-pressure cylinder 9 is defined as B, where B < A, and A and B are numbers greater than 0. The height of the moving blades is an important parameter that determines the flow area of ​​the low-pressure cylinder 9. Since the higher the rotor moving blades of the low-pressure cylinder 9, the larger the flow area and the lower the turbine efficiency, the moving blades in the low-pressure cylinder 9 are reduced. Furthermore, by lowering the moving blade height within the low-pressure cylinder 9, and by making this reduction smaller compared to the moving blade height in the prior art, the flow area is effectively reduced. This reduces the minimum required exhaust steam volume at low loads, thus meeting the requirements for continuous turbine operation when the low-pressure heat load is insufficient.

[0024] In some embodiments, a valve 701 is connected in series between the third diversion pipe 7 and the air inlet of the low-pressure cylinder 9. When the steam from the high-pressure cylinder 6 enters the low-pressure cylinder 9, the opening degree of the valve 701 is adjusted to regulate the steam flow rate entering the low-pressure cylinder 9.

[0025] Based on fluid mechanics principles, the fluid cross-section is adjusted by changing the opening degree of valve 701, thereby altering the steam flow rate entering the low-pressure cylinder 9. When steam from the intermediate-high pressure cylinder 6 enters the low-pressure cylinder 9, the flow rate entering the low-pressure cylinder 9 can be precisely controlled by adjusting the opening degree of valve 701, ensuring that the low-pressure system remains within a safe and economical operating range under different working conditions.

[0026] In some embodiments, the outlet of the fourth diverter is also connected in parallel with a low-pressure steam cylinder 14, and a low-pressure desuperheater 16 is connected in series between the low-pressure steam cylinder 14 and the sixth diverter 11.

[0027] The outlet of the fourth branch pipe is designed with a low-pressure steam cylinder 14 connected in parallel, and a low-pressure desuperheater 16 is connected in series between the low-pressure steam cylinder 14 and the sixth branch pipe 11. The low-pressure desuperheater 16 serves as a supplementary steam supply to low-pressure heat users, providing necessary supplementary regulation when the low-pressure heat load increases significantly. Normally, the exhaust steam from the low-pressure cylinder 9 is used to supply steam to the low-pressure heat load. The exhaust steam from the low-pressure cylinder 9 is designed with a margin; only when the low-pressure heat load increases significantly is the low-temperature desuperheater 16 used to supplement the heat supply to the low-pressure users. This helps reduce the cost of low-temperature steam supply, while ensuring that heat users receive suitable steam parameters, improving the overall system's economy and operating efficiency.

[0028] In summary, the small-displacement back-pressure steam turbine system provided by this utility model, through modification of the low-pressure cylinder 9 and limitation of the moving blade height, reduces the moving blade height compared to existing designs, thereby reducing the flow area of ​​the low-pressure cylinder 9 and lowering the minimum required discharge volume for safe continuous operation. This allows for safe and stable continuous operation even under low-pressure heat load conditions. This design effectively alleviates the problem of insufficient discharge volume in the original design under low-pressure heat load conditions, ensuring that no safety hazards arise due to insufficient discharge volume of the low-pressure cylinder 9 during operation. A regulating valve is installed in series between the third branch pipe 7 and the inlet of the low-pressure cylinder 9, simultaneously achieving precise control of the medium-pressure heat load. The regulating valve can adjust the steam distribution in real time according to changes in the medium-pressure heat load, enabling dynamic balance of the medium- and low-pressure steam supply ratio, ensuring that the low-pressure system can still meet its heat load requirements when the medium-pressure load fluctuates. By connecting a low-pressure steam distributor cylinder 14 and a low-pressure desuperheater / pressure reducer 16 in parallel at the outlet of the fourth distributor pipe, a supplementary steam supply is provided to low-pressure heat users, offering necessary supplementary regulation when the low heat load increases significantly. Normally, the exhaust steam from the low-pressure cylinder 9 is used to supply steam to the low-pressure heat load. The exhaust steam from the low-pressure cylinder 9 is designed with a margin; only when the low heat load increases significantly is the low-temperature desuperheater / pressure reducer 16 used to supplement the heat supply to the low-pressure users. This helps reduce the cost of low-temperature steam supply while ensuring that heat users receive suitable steam parameters, improving the overall system's economy and operating efficiency. By designing the high-pressure cylinder 6 and low-pressure cylinder 9 in a head-to-head configuration, the high-pressure cylinder 6 and low-pressure cylinder 9 can be arranged in the same outer cylinder to achieve physical isolation while sharing the same rotor. This achieves a layout similar to two steam turbines. This scheme modifies only the low-pressure cylinder 9 without changing the original flow area of ​​the high-pressure cylinder 6, avoiding excessive changes to the overall structure of the steam turbine, reducing modification costs, shortening the construction period, and ensuring that the modified system still meets the original compliance requirements. It has high value for promotion and application.

[0029] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A low exhaust steam back pressure steam turbine system characterized by, The main steam pipe has a gas outlet connected with a first branch pipe and a second branch pipe in parallel, the gas outlet of the first branch pipe is connected with a medium-pressure cylinder for transmitting steam to a medium-pressure heat user, a medium-pressure desuperheater and pressure reducer is connected in series between the first branch pipe and the medium-pressure cylinder, and the gas outlet of the second branch pipe is connected with a high-medium-pressure cylinder; the gas outlet of the high-medium-pressure cylinder has a third branch pipe and a fourth branch pipe in parallel, the third branch pipe is connected with the gas inlet of a low-pressure cylinder; the low-pressure cylinder is arranged opposite to the high-medium-pressure cylinder; the low-pressure cylinder further comprises a fifth branch pipe and a sixth branch pipe, the gas outlet of the fifth branch pipe is connected with a first high-pressure heater, the gas outlet of the sixth branch pipe has a deaerator and a low-pressure cylinder in parallel, the low-pressure cylinder is used for transmitting steam to a low-pressure heat user; and the gas outlet of the fourth branch pipe has a second high-pressure heater and the medium-pressure cylinder in parallel.

2. A low specific output back pressure steam turbine system according to claim 1, characterized by, The height of a moving blade of a conventional low-pressure cylinder is defined as A, and the height of a moving blade of the low-pressure cylinder is B, B 3. A low specific output back pressure steam turbine system according to claim 1, wherein, A valve is connected in series between the third branch pipe and the gas inlet of the low-pressure cylinder, and the opening and closing degree of the valve is adjusted when steam of the high-medium-pressure cylinder enters the low-pressure cylinder, so as to control the steam flow entering the low-pressure cylinder.

4. A low specific output back pressure steam turbine system in accordance with claim 1 wherein, The gas outlet of the fourth branch pipe further has the low-pressure cylinder in parallel, and a low-pressure desuperheater and pressure reducer is connected in series between the low-pressure cylinder and the sixth branch pipe.

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