A steam inlet system for a feedwater pump turbine

Abstract

The present invention relates to a feedwater pump steam turbine steam inlet system, comprising a feedwater pump steam turbine, a steam turbine main gas circuit, a low-pressure steam source five-extraction steam supply, an auxiliary steam supply, and a high-pressure steam source secondary reheat steam supply. One end of the steam turbine main gas circuit is connected to the feedwater pump steam turbine, and the other end is respectively connected to the low-pressure steam source five-extraction steam supply, the auxiliary steam supply, and the high-pressure steam source secondary reheat steam supply. The high-pressure steam source secondary reheat steam supply is provided with a feedwater pump steam turbine high-pressure valve, which is in a normally closed state. Both ends of the feedwater pump steam turbine high-pressure valve are connected in parallel via pipelines to feedwater pump steam turbine high-pressure valve bypass valves, which are in a normally open state. Compared with the prior art, the present invention has the advantages of reducing steam loss caused by draining and avoiding disturbances to the system caused by the sudden opening of the high-pressure regulating valve.

Description

Technical Field

[0001] The present invention relates to the technical field of steam sources for feedwater pump turbines, and in particular to a steam inlet system for feedwater pump turbines. Background Art

[0002] Currently, if Figure 1 As shown, the existing solution provides three steam sources for the feedwater pump turbine: auxiliary steam, low-pressure steam source five-extraction steam, and high-pressure steam source secondary reheat steam. The feedwater pump turbine operates normally with five-extraction steam. When steam source pressure is insufficient, the high-pressure steam inlet regulating valve automatically opens to maintain a stable feedwater pump turbine speed. Auxiliary steam is used for feedwater pump turbine startup, shutdown, and emergency conditions, and is only provided as an emergency backup.

[0003] Because the feedwater pump turbine's high-pressure steam source serves as a backup steam source during normal operation, the steam source pipe must be kept warm and in standby mode to prevent cold steam and water from entering the turbine when it is turned on, potentially damaging the equipment. Currently, to maintain this warm state, the drain valve in front of the feedwater pump turbine's high-pressure regulating valve is kept open to maintain steam flow. This method ensures normal steam temperature in front of the high-pressure regulating valve and prevents cold steam and water accumulation. However, keeping the drain valve open for extended periods can result in excess steam and water loss, and high-pressure steam can scour the drain valve, causing it to leak. Summary of the Invention

[0004] The purpose of the present invention is to provide a feedwater pump turbine steam inlet system in order to overcome the defects of the above-mentioned prior art that the drain in front of the high-pressure regulating valve of the feedwater pump turbine is kept open, the drain will cause excess steam and water loss, and the high-pressure steam will flush the drain valve and cause it to leak.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A feedwater pump turbine steam inlet system comprises a feedwater pump turbine, a turbine main gas circuit, a low-pressure steam source five-extraction steam supply circuit, an auxiliary steam supply circuit and a high-pressure steam source secondary reheat steam supply circuit, wherein one end of the turbine main gas circuit is connected to the feedwater pump turbine, and the other end is respectively connected to the low-pressure steam source five-extraction steam supply circuit, the auxiliary steam supply circuit and the high-pressure steam source secondary reheat steam supply circuit, the high-pressure steam source secondary reheat steam supply circuit is provided with a feedwater pump turbine high-pressure valve, the feedwater pump turbine high-pressure valve is in a normally closed state, and both ends of the feedwater pump turbine high-pressure valve are connected in parallel with a feedwater pump turbine high-pressure valve bypass door through a pipeline, and the feedwater pump turbine high-pressure valve bypass door is in a normally open state.

[0007] Furthermore, the diameter of the pipeline where the bypass door of the high-pressure valve of the feedwater pump turbine is located is smaller than the diameter of the main pipeline of the secondary reheat steam source of the high-pressure steam source.

[0008] Furthermore, the control end of the feedwater pump turbine high-pressure valve is connected to a threshold switch control circuit, and the turbine main gas circuit is provided with a feedwater pump turbine steam inlet pressure transmitter, which is connected to the input end of the threshold switch control circuit.

[0009] Furthermore, the threshold switch control circuit includes a comparator and a reference voltage source, the reference voltage source is connected to the threshold voltage end of the comparator, the feedwater pump turbine steam inlet pressure transmitter outputs a voltage signal, the output end of the feedwater pump turbine steam inlet pressure transmitter is connected to the input end of the comparator, and the output end of the comparator is connected to the control end of the feedwater pump turbine high-pressure valve.

[0010] Furthermore, a feedwater pump turbine main steam valve and a feedwater pump turbine low-pressure valve are connected in series in the main gas circuit of the steam turbine, and a feedwater pump turbine inlet local pressure gauge is connected to the main gas circuit of the steam turbine.

[0011] Furthermore, the five-axis steam inlet check valve of the feedwater pump turbine, the first five-axis steam inlet electric door and the second five-axis steam inlet electric door of the feedwater pump turbine are connected in series in the five-axis steam extraction route of the low-pressure steam source, and the five-axis steam inlet flow transmitter of the feedwater pump turbine is connected in parallel in the pipeline between the first five-axis steam inlet electric door and the second five-axis steam inlet electric door of the feedwater pump turbine.

[0012] Furthermore, a drain expansion tank is connected to the pipeline between the first feedwater pump steam turbine five-axis electric steam inlet door and the second feedwater pump steam turbine five-axis electric steam inlet door.

[0013] Furthermore, the auxiliary steam supply line is connected in series with an auxiliary steam inlet electric door of a feedwater pump turbine, and the auxiliary steam supply line is connected to an auxiliary steam drain expansion tank.

[0014] Furthermore, the secondary reheat steam supply path of the high-pressure steam source is also connected in series with a feedwater pump turbine secondary reheat steam inlet electric door.

[0015] Furthermore, both ends of the feedwater pump turbine secondary reheat steam inlet electric door are connected to a drain expansion tank.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) This solution adds a feedwater pump turbine high-pressure regulating valve bypass door to the feedwater pump turbine steam inlet system and keeps it normally open; and keeps the feedwater pump turbine high-pressure valve normally closed. Through the normally open feedwater pump turbine high-pressure regulating valve bypass door, a small amount of steam is always allowed to enter the feedwater pump turbine through the bypass door, so that the high-pressure steam source pipeline is in a long-term warm-up state, avoiding the disturbance to the system caused by the sudden opening of the high-pressure regulating valve.

[0018] (2) This scheme adds a feedwater pump turbine high-pressure regulating valve bypass valve in the feedwater pump turbine steam inlet system, which is beneficial to reducing the steam loss caused by drainage.

[0019] (3) When the steam inlet pressure of the feedwater pump turbine is insufficient, the high-pressure regulating valve automatically opens to maintain the stable steam inlet pressure and the stable speed of the feedwater pump turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the existing structure of a feedwater pump turbine steam inlet system provided in the background technology of the present invention;

[0021] Figure 2 This is a structural schematic diagram of a feedwater pump turbine steam inlet system provided in an embodiment of the present invention;

[0022] In the figure, 1. feedwater pump steam turbine, 2. feedwater pump steam turbine main steam valve, 3. feedwater pump steam turbine low-pressure valve, 4. feedwater pump steam turbine inlet steam local pressure gauge, 5. feedwater pump steam turbine inlet steam pressure transmitter, 6. feedwater pump steam turbine five-axis steam inlet check valve, 7. first feedwater pump steam turbine five-axis steam inlet electric door, 8. feedwater pump steam turbine five-axis steam inlet flow transmitter, 9. second feedwater pump steam turbine five-axis steam inlet electric door, 10. drain expansion tank, 11. feedwater pump steam turbine auxiliary steam inlet electric door, 12. auxiliary steam drain expansion tank, 13. feedwater pump steam turbine high-pressure valve, 14. feedwater pump steam turbine high-pressure valve bypass door, 15. feedwater pump steam turbine secondary reheat steam inlet electric door. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0026] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0028] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0029] Example 1

[0030] like Figure 2 As shown, this embodiment provides a feedwater pump turbine steam inlet system, including a feedwater pump turbine 1, a turbine main gas circuit, a low-pressure steam source five extraction steam circuits, an auxiliary steam circuit and a high-pressure steam source secondary reheat steam circuit. One end of the turbine main gas circuit is connected to the feedwater pump turbine 1, and the other end is respectively connected to the low-pressure steam source five extraction steam circuits, the auxiliary steam circuit and the high-pressure steam source secondary reheat steam circuit. The high-pressure steam source secondary reheat steam circuit is provided with a feedwater pump turbine high-pressure valve 13, which is in a normally closed state. Both ends of the feedwater pump turbine high-pressure valve 13 are connected in parallel with a feedwater pump turbine high-pressure valve bypass door 14 through a pipeline, and the feedwater pump turbine high-pressure valve bypass door 14 is in a normally open state.

[0031] The diameter of the pipeline where the bypass door 14 of the high-pressure valve of the feedwater pump turbine is located is smaller than the diameter of the main pipeline of the secondary reheat steam source of the high-pressure steam source.

[0032] This solution adds a bypass valve for the high-pressure regulating valve of the feedwater pump turbine. During normal operation, the feedwater pump turbine uses five-stage extraction steam, with the high-pressure steam source serving as a backup source. After the modification, the bypass valve of the feedwater pump turbine's high-pressure regulating valve is opened, and water is drained before closing the regulating valve. This allows a small amount of steam to enter the feedwater pump turbine through the bypass valve, keeping the high-pressure steam source pipeline in a long-term warm state.

[0033] When the steam inlet pressure of the feedwater pump turbine is insufficient, the high-pressure regulating valve opens automatically to maintain stable steam inlet pressure and feedwater pump turbine speed.

[0034] Optionally, the control end of the feedwater pump turbine high-pressure valve 13 is connected to a threshold switch control circuit, and the main gas circuit of the turbine is provided with a feedwater pump turbine steam inlet pressure transmitter 5, which is connected to the input end of the threshold switch control circuit.

[0035] The threshold switch control circuit includes a comparator and a reference voltage source. The reference voltage source is connected to the threshold voltage end of the comparator. The feedwater pump turbine steam inlet pressure transmitter 5 outputs a voltage signal. The output end of the feedwater pump turbine steam inlet pressure transmitter 5 is connected to the input end of the comparator. The output end of the comparator is connected to the control end of the feedwater pump turbine high-pressure valve 13.

[0036] The greater the steam inlet pressure detected by the feedwater pump turbine steam inlet pressure transmitter 5, the greater the output voltage signal; the comparator compares the voltage signal output by the feedwater pump turbine steam inlet pressure transmitter 5 with the reference voltage set by the reference voltage source. When the voltage signal is less than the reference voltage, a high-level signal is output to the feedwater pump turbine high-pressure valve 13, and the feedwater pump turbine high-pressure valve 13 is opened; otherwise, a low-level signal is output, and the feedwater pump turbine high-pressure valve 13 remains normally closed.

[0037] Specifically, in the application scenario of this embodiment, the main steam valve 2 of the feedwater pump turbine and the low-pressure valve 3 of the feedwater pump turbine are connected in series in the main gas circuit of the turbine, and the main gas circuit of the turbine is connected to the local pressure gauge 4 of the feedwater pump turbine steam inlet.

[0038] The five extraction steam routes of the low-pressure steam source are connected in series in sequence with the feedwater pump steam turbine five-axis steam inlet check valve 6, the first feedwater pump steam turbine five-axis steam inlet electric door 7 and the second feedwater pump steam turbine five-axis steam inlet electric door 9. The pipeline between the first feedwater pump steam turbine five-axis steam inlet electric door 7 and the second feedwater pump steam turbine five-axis steam inlet electric door 9 is connected in parallel with the feedwater pump steam turbine five-axis steam inlet flow transmitter 8.

[0039] The pipeline between the first feedwater pump steam turbine five-axis steam inlet electric door 7 and the second feedwater pump steam turbine five-axis steam inlet electric door 9 is connected with a drain expansion tank 10.

[0040] The auxiliary steam supply line is connected in series with the feed water pump turbine auxiliary steam inlet electric door 11, and the auxiliary steam supply line is connected to the auxiliary steam drain expansion tank 12.

[0041] The secondary reheat steam supply path of the high-pressure steam source is also connected in series with the feed water pump turbine secondary reheat steam inlet electric door 15.

[0042] Both ends of the feedwater pump turbine secondary reheat steam inlet electric door 15 are connected to the drain expansion tank 10.

[0043] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A feedwater pump steam turbine steam inlet system, comprising a feedwater pump steam turbine (1), a steam turbine main gas path, a low-pressure steam source five-extraction steam path, an auxiliary steam path, and a high-pressure steam source secondary reheat steam path, wherein one end of the steam turbine main gas path is connected to the feedwater pump steam turbine (1), and the other end is respectively connected to the low-pressure steam source five-extraction steam path, the auxiliary steam path, and the high-pressure steam source secondary reheat steam path, wherein the high-pressure steam source secondary reheat steam path is provided with a feedwater pump steam turbine high-pressure valve (13), characterized in that: The feedwater pump steam turbine high-pressure valve (13) is in a normally closed state, and feedwater pump steam turbine high-pressure valve bypass doors (14) are connected in parallel to both ends of the feedwater pump steam turbine high-pressure valve (13) through pipelines, and the feedwater pump steam turbine high-pressure valve bypass doors (14) are in a normally open state; The control end of the feedwater pump steam turbine high-pressure valve (13) is connected to a threshold switch control circuit, and the main gas path of the steam turbine is provided with a feedwater pump steam turbine inlet steam pressure transmitter (5), and the feedwater pump steam turbine inlet steam pressure transmitter (5) is connected to the input end of the threshold switch control circuit; The threshold switch control circuit includes a comparator and a reference voltage source, the reference voltage source is connected to the threshold voltage terminal of the comparator, the feedwater pump turbine inlet steam pressure transmitter (5) outputs a voltage signal, the output terminal of the feedwater pump turbine inlet steam pressure transmitter (5) is connected to the input terminal of the comparator, and the output terminal of the comparator is connected to the control terminal of the feedwater pump turbine high-pressure valve (13); The five-axis steam inlet check valve (6) of the feedwater pump steam turbine, the first five-axis steam inlet electric door (7) and the second five-axis steam inlet electric door (9) of the feedwater pump steam turbine are sequentially connected in series in the five-axis steam inlet of the low-pressure steam source, and the pipeline between the first five-axis steam inlet electric door (7) and the second five-axis steam inlet electric door (9) of the feedwater pump steam turbine is connected in parallel with a five-axis steam inlet flow transmitter (8) of the feedwater pump steam turbine; The pipeline between the first feedwater pump steam turbine five-axis steam inlet electric door (7) and the second feedwater pump steam turbine five-axis steam inlet electric door (9) is connected to a drain expansion tank (10).

2. A feedwater pump turbine steam inlet system according to claim 1, characterized in that: The diameter of the pipeline where the feedwater pump steam turbine high-pressure valve bypass door (14) is located is smaller than the diameter of the main pipeline of the high-pressure steam source secondary reheat steam source.

3. The feedwater pump turbine steam inlet system according to claim 1, characterized in that: A feedwater pump steam turbine main steam valve (2) and a feedwater pump steam turbine low-pressure valve (3) are connected in series in the steam turbine main gas circuit, and a feedwater pump steam turbine inlet local pressure gauge (4) is connected to the steam turbine main gas circuit.

4. The feedwater pump turbine steam inlet system according to claim 1, characterized in that: The auxiliary steam supply line is connected in series with a feedwater pump turbine auxiliary steam inlet electric door (11), and the auxiliary steam supply line is connected to an auxiliary steam drain expansion tank (12).

5. The feedwater pump turbine steam inlet system according to claim 1, characterized in that: The secondary reheat steam supply path of the high-pressure steam source is also connected in series with a feedwater pump turbine secondary reheat steam inlet electric door (15).

6. A feedwater pump turbine steam inlet system according to claim 5, characterized in that: Both ends of the feedwater pump turbine secondary reheat steam inlet electric door (15) are connected to a drain expansion tank (10).

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