Steam turbine shaft seal steam heat recycling device

Abstract

The utility model relates to the technical field of steam turbine shaft seal overflow devices, in particular to a steam turbine shaft seal steam heat recycling device. The utility model provides a steam turbine shaft seal steam heat recycling device which comprises a shaft seal overflow main pipe and an overflow bypass pipe connected with the shaft seal overflow main pipe. The overflow bypass pipe comprises a bypass valve communicated with the shaft seal overflow mother pipe, the bypass valve is communicated with a No.7 low-pressure heater through a water pipe, and a first electric gate valve is arranged between the bypass valve and the No.7 low-pressure heater; the bypass valve is communicated with the condenser A through a water pipe, and a second electric gate valve is arranged between the bypass valve and the condenser A. The technical problem that in the prior art, a shaft seal overflow recycling device has limitation is solved.

Description

Technical Field

[0001] This utility model relates to the technical field of turbine shaft seal overflow device, and in particular to a turbine shaft seal steam heat recovery device. Background Technology

[0002] The current unit's shaft sealing system is designed for self-sealing operation, with automatic pressure and temperature control. The system includes an automatic shaft seal pressure adjustment device, an overflow pressure relief device, and a shaft seal steam return device. The function of the shaft sealing system is to prevent air leakage into the cylinder when the cylinder pressure is negative, and to prevent steam leakage into the air when the cylinder pressure is positive. During unit startup and shutdown, the pressure inside the high-pressure, intermediate-pressure, and low-pressure cylinders is negative, lower than atmospheric pressure. To prevent air from leaking into the cylinders, steam is used to seal the shaft seals at both ends of the cylinders. The steam for the shaft seals comes from the plant's auxiliary steam (1.1 MPa, 330℃). However, when the unit is connected to the grid and the load increases, the steam pressure inside the high-pressure and intermediate-pressure cylinders changes from negative to positive, while the low-pressure cylinder remains negative. When the unit load exceeds 40% of the rated load, the steam leakage from the high-pressure and intermediate-pressure cylinder shaft seals meets the steam demand of the low-pressure shaft seal. The shaft seal steam supply is switched from auxiliary steam to steam leakage from the high-pressure and intermediate-pressure cylinder shaft seals (20 kPa, 310℃). When the shaft seal steam supply exceeds the set value, the excess steam is discharged into the condenser, achieving a self-sealing operation mode. The average enthalpy of steam leakage from the high and medium pressure main steam valve stems of the steam turbine is 3215 kJ / kg, which also has high heat utilization value. The original design directly discharged the steam to the condenser, which not only wasted this part of the steam heat, but also increased the heat load of the condenser.

[0003] Chinese utility model patent CN220059680U, published on November 21, 2023, discloses a shaft seal overflow reuse device, including a shaft seal header and a #7 low-pressure heater. The #7 low-pressure heater is connected to a low-pressure heater extraction pipe. A steam pipe is welded to the shaft seal header and connected to it. The end of the steam pipe furthest from the shaft seal header is connected to the low-pressure heater extraction pipe, facilitating the diversion of steam from the shaft seal header to the low-pressure heater extraction pipe. Under the action of the #7 low-pressure heater, the steam heat source is heated, reducing heat waste. Two manual shut-off valves are installed on the steam pipe for flexible system isolation. However, this patent cannot be applied to all turbine scenarios.

[0004] This application proposes a novel device for reusing steam heat from turbine shaft seals. Summary of the Invention

[0005] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a steam turbine shaft seal steam heat reuse device, which aims to solve the technical problem that the shaft seal overflow reuse device in the prior art has limitations.

[0006] To achieve the above objectives, this utility model proposes a steam turbine shaft seal steam heat recovery device, comprising a shaft seal overflow header and an overflow bypass pipe connected to the shaft seal overflow header; the overflow bypass pipe includes a bypass valve connected to the shaft seal overflow header, the bypass valve being connected to a No. 7 low-pressure heater via a water pipe, and a first electric gate valve being provided between the bypass valve and the No. 7 low-pressure heater; the bypass valve being connected to condenser A via a water pipe, and a second electric gate valve being provided between the bypass valve and condenser A.

[0007] Preferably, the overflow bypass pipe includes a front manual valve and a rear manual valve connected to both ends of the bypass valve; the overflow bypass pipe also includes pneumatic regulating valves disposed on the front manual valve and the rear manual valve.

[0008] Preferably, drainage pipes are provided on both sides of the first electric gate valve and drain water to condenser B; drainage pipes are provided on both sides of the rear manual valve and the outlet of the bypass valve and drain water to condenser A.

[0009] Preferably, the bypass valve outlet is connected to a three-way elbow, one of which is connected to the No. 7 low-pressure heater.

[0010] Preferably, a branch is led out from the shaft seal overflow header; the branch includes a standard orifice plate flow meter connected to the shaft seal overflow header, a front manual gate valve connected to the standard orifice plate flow meter, a pneumatic regulating valve connected to the front manual gate valve, and a rear manual gate valve connected to the pneumatic regulating valve; the outlet end of the rear manual gate valve is connected to the No. 7 low-pressure heater.

[0011] As a preferred embodiment, the outlet ends of the front manual gate valve, the pneumatic regulating valve, and the rear manual gate valve are all led out to a drain pipe and merged into a main pipe; each drain pipe is equipped with a welded shut-off valve.

[0012] Preferably, the front manual gate valve is a DN400 welded valve, the pneumatic regulating valve is a DN400 flanged proportional pneumatic valve, the rear manual gate valve is a DN450 welded valve, and the welded shut-off valve is a DN25 valve.

[0013] Compared with the prior art, the beneficial effects of the turbine shaft seal steam heat recovery device provided by this utility model are as follows:

[0014] 1. A branch line is drawn from the shaft seal overflow header, and the outlet of the branch line is introduced into the No. 7 low-pressure heater so that the shaft seal steam can be reused, saving energy.

[0015] 2. Connect a new pipeline from the bypass valve of the shaft seal overflow to the No. 7 low-pressure heater. Add a set of electric gate valves (first electric gate valve and second electric gate valve) to both the original pipeline and the new pipeline to control the steam inlet. Use the original regulating valve to control the pressure of the shaft seal steam header. This will have virtually no impact on the original system.

[0016] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a diagram of the waterway structure modified from the shaft seal overflow header in this embodiment of the utility model.

[0018] Figure 2 yes Figure 1 An enlarged structural diagram of the modified section.

[0019] Figure 3 This is a schematic diagram of the left half of another modified structure in an embodiment of this utility model.

[0020] Figure 4 This is a schematic diagram of the right half of another modified structure in an embodiment of this utility model.

[0021] Figure 5 This is a schematic diagram showing the position of the second electric gate valve in the pipeline according to an embodiment of this utility model.

[0022] Figure 6 This is a schematic diagram showing the position of the first electric gate valve in the pipeline according to an embodiment of this utility model.

[0023] in:

[0024] 1-Shaft seal overflow header; 11-Bypass valve; 12-Front manual valve; 13-Rear manual valve; 14-Pneumatic regulating valve; 2-Overflow bypass pipe; 37-No. 1 low-pressure heater; 4-First electric gate valve; 5-A condenser; 6-Second electric gate valve; 7-B condenser; 8-Tee elbow; 9-Branch; 91-Standard orifice plate flow meter; 92-Front manual gate valve; 93-Pneumatic regulating valve; 94-Rear manual gate valve; 95-Welded shut-off valve. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit its scope. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the present utility model.

[0026] In the description of this utility model, it should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to or indirectly connected to the other element.

[0027] In the description of this utility model, it should be noted that the terms "center," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. 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," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0028] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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. Example 1

[0029] See Figure 1 and Figure 2 This utility model embodiment provides a steam turbine shaft seal steam heat recovery device, wherein a branch line 9 is led out from the shaft seal overflow header 1. The wasted steam heat is recovered through this branch line. The specific structure of the branch line 9 is as follows:

[0030] Figure 1 This is a schematic diagram of the pipeline flow direction structure for the newly added branch, showing its distribution within the original pipeline. Figure 2This is a pipeline layout diagram for the newly added branch. The branch includes a standard orifice flow meter 91 connected to the shaft seal overflow header 1, a front manual gate valve 92 connected to the standard orifice flow meter 91, a pneumatic regulating valve 93 connected to the front manual gate valve 92, and a rear manual gate valve 94 connected to the pneumatic regulating valve 93; the outlet of the rear manual gate valve 94 is connected to the No. 7 low-pressure heater 3. Introducing steam from the shaft seal overflow header into the No. 7 low-pressure heater 3 for heat recovery and utilization significantly saves energy.

[0031] Furthermore, the outlet ends of the front manual gate valve 92, the pneumatic regulating valve 93, and the rear manual gate valve 94 are all led out to a drain pipe and merged into a main pipe, which is then led to a 20m³ drain expansion container. Each drain pipe is equipped with a welded shut-off valve 95. The drain pipe system greatly improves safety and extends the service life of the pipeline.

[0032] Furthermore, the front manual gate valve 92 is a DN400 welded valve, the pneumatic regulating valve 93 is a DN400 flanged proportional pneumatic valve, the rear manual gate valve 94 is a DN450 welded valve, and the welded shut-off valve 95 is a DN25 valve. Example 2

[0033] Although heat recovery is possible in Embodiment 1, introducing steam from the shaft seal overflow header into the No. 7 low-pressure heater 3 requires a separate pneumatic regulating valve and front and rear manual gate valves. Pressure control of the shaft seal overflow header is adjusted by the opening of two regulating valves (one built-in and one newly added), increasing the difficulty of adjustment. In an optional embodiment, a new recovery method is added. In practical use, the scheme of Embodiment 1 can be used simultaneously, the scheme of Embodiment 2 can be used, or both schemes of Embodiments 1 and 2 can be used to address different actual situations. Currently, the scheme of Embodiment 2 is the preferred option.

[0034] See Figure 3-4 A turbine shaft seal steam heat recovery device includes a shaft seal overflow header 1 and an overflow bypass pipe 2 connected to the shaft seal overflow header 1; the overflow bypass pipe 2 includes a bypass valve 11 connected to the shaft seal overflow header 1, the bypass valve 11 is connected to a No. 7 low-pressure heater 3 through a water pipe, and a first electric gate valve 4 is provided between the bypass valve 11 and the No. 7 low-pressure heater 3; the bypass valve 11 is connected to an A condenser 5 through a water pipe, and a second electric gate valve 6 is provided between the bypass valve 11 and the A condenser 5.

[0035] in Figure 3 and Figure 4 The combined diagram forms a complete pipeline layout, which is divided into two parts for easy display in the application. Figure 3 The left half Figure 4 This is the right half, where the dividing line is a dashed line and does not represent an actual pipeline. Figure 3 and Figure 4 A complete pipeline can be assembled using dotted lines.

[0036] See Figure 4 The overflow bypass pipe 2 includes a front manual valve 12 and a rear manual valve 13 connected to both ends of the bypass valve 11; the overflow bypass pipe 2 also includes a pneumatic regulating valve 14 disposed on the front manual valve 12 and the rear manual valve 13. Drainage pipes are provided on both sides of the first electric gate valve 4, draining water to condenser B 7; drainage pipes are provided on both sides of the rear manual valve 13 and the outlet end of the bypass valve 11, draining water to condenser A 5. The drainage pipes greatly improve safety and extend the service life of the pipes.

[0037] In this embodiment, a new pipeline is connected to the No. 7 low-pressure heater 3 via bypass valve 11. A first electric gate valve 4 and a second electric gate valve 6 are added to both the original and new pipelines to control steam entry. The original regulating valve is used to control the pressure of the shaft seal steam header, thus having virtually no impact on the original system. It should be noted that bypass valve 11, the front manual valve 12, the rear manual valve 13, and the pneumatic regulating valve 14 are all installed on the original pipeline. The first electric gate valve 4 is installed on the new pipeline to connect to the No. 7 low-pressure heater 3. The second electric gate valve 6 is installed on the original pipeline.

[0038] For details of the modified structure, please refer to Figure 5 and Figure 6 Actual pipeline layout diagram.

[0039] See Figure 6 The bypass valve 11 has a three-way elbow 8 connected to its outlet. One channel of the three-way elbow 8 is connected to the low-pressure heater 3 (No. 7). The pipe extending from the top of the three-way elbow 8 corresponds to... Figure 4 The middle section is the newly opened pipeline for the first electric gate valve 4.

[0040] Specifically, the existing bend after the bypass valve of the shaft seal overflow was replaced with a tee, leading out a pipeline to the steam inlet pipeline of the No. 7 low-pressure heater. An expansion joint was added to the horizontal pipeline to eliminate the impact of pipeline expansion. A first electric gate valve was added to the pipeline before entering the condenser, passing through the shell of the No. 2 unit B condenser and entering the condenser throat before extending to the steam inlet pipe of the No. 7 low-pressure heater. A second electric gate valve was installed in the original shaft seal overflow pipeline to the A condenser. When the unit load exceeds 400MW, the electric valve for shaft seal overflow to the A condenser is closed, and the electric valve for shaft seal overflow to the No. 7 low-pressure heater is opened, allowing excess shaft seal steam to flow to the No. 7 low-pressure heater for reuse. Drainage pipelines were added before and after the valves simultaneously. On the one hand, the high-calorific-value steam in the shaft seal return steam is reused, improving the unit's economy. On the other hand, the recovery and reuse of shaft seal overflow steam is achieved with minimal changes to the shaft seal main pipe pressure control logic. This can be achieved simply by setting the opening and closing of the two electric gate valves when the unit load is around 400MW.

[0041] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for recovering heat from steam seals of a steam turbine, characterized in that: It includes a shaft seal overflow header (1) and an overflow bypass pipe (2) connected to the shaft seal overflow header (1); the overflow bypass pipe (2) includes a bypass valve (11) connected to the shaft seal overflow header (1), the bypass valve (11) is connected to the No. 7 low-pressure heater (3) through a water pipe, and a first electric gate valve (4) is provided between the bypass valve (11) and the No. 7 low-pressure heater (3); the bypass valve (11) is connected to the A condenser (5) through a water pipe, and a second electric gate valve (6) is provided between the bypass valve (11) and the A condenser (5).

2. The turbine shaft seal steam heat recovery device as described in claim 1, characterized in that: The overflow bypass pipe (2) includes a front manual valve (12) and a rear manual valve (13) connected to both ends of the bypass valve (11); the overflow bypass pipe (2) also includes a pneumatic regulating valve (14) disposed on the front manual valve (12) and the rear manual valve (13).

3. The turbine shaft seal steam heat recovery device as described in claim 2, characterized in that: The first electric gate valve (4) is provided with drainage pipes on both sides and drains water to condenser B (7); the rear manual valve (13) and the outlet of the bypass valve (11) are provided with drainage pipes and drain water to condenser A (5).

4. The turbine shaft seal steam heat recovery device as described in claim 1, characterized in that: The bypass valve (11) is connected to a three-way elbow (8) at its outlet, and one of the three-way elbows (8) is connected to the No. 7 low-pressure heater (3).

5. The turbine shaft seal steam heat recovery device as described in claim 1, characterized in that: A branch line (9) is led out from the shaft seal overflow header (1); the branch line includes a standard orifice plate flow meter (91) connected to the shaft seal overflow header (1), a front manual gate valve (92) connected to the standard orifice plate flow meter (91), a pneumatic regulating valve (93) connected to the front manual gate valve (92), and a rear manual gate valve (94) connected to the pneumatic regulating valve (93); the outlet end of the rear manual gate valve (94) is connected to the No. 7 low-pressure heater (3).

6. The turbine shaft seal steam heat recovery device as described in claim 5, characterized in that: The outlet ends of the front manual gate valve (92), the pneumatic regulating valve (93), and the rear manual gate valve (94) are all led out to a drain pipe and merged into a main pipe; each drain pipe is equipped with a welded stop valve (95).

7. The turbine shaft seal steam heat recovery device as described in claim 6, characterized in that: The front manual gate valve (92) is a welded valve of DN400, the pneumatic regulating valve (93) is a DN400 flanged proportional pneumatic valve, the rear manual gate valve (94) is a welded valve of DN450, and the welded stop valve (95) is a valve of DN25.

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