Steam source system for steam turbine

Abstract

The steam source system comprises a first steam source, a second steam source and a mixing device, the first steam source communicates with a steam inlet of the steam turbine and a first steam inlet of the mixing device, and the second steam source communicates with a second steam inlet of the mixing device. The mixing device is used for mixing steam of the first steam source and steam of the second steam source, a steam outlet of the mixing device is communicated with a steam inlet of the steam turbine and used for supplying the mixed steam to the steam turbine, and the steam pressure of the second steam source is larger than that of the first steam source. According to the technical scheme, for the feed pump turbine, the fluctuation of switching the power from the first steam source to the mixed steam is smaller than the fluctuation of directly switching the power from the first steam source to the second steam source. The mixed steam is formed by utilizing the pressure of the first steam source and the pressure of the second steam source, and heat energy of the second steam source cannot be wasted.

Description

Technical Field

[0001] The present disclosure relates to the field of steam turbines, and in particular, to a steam source system for a steam turbine. Background Art

[0002] The feedwater pump steam turbine is a special type of steam turbine in a thermal power generating unit, which is used to drive the feedwater pump to provide the necessary feedwater circulation for the boiler. The steam source of the feedwater pump steam turbine is generally provided by the large steam turbine in the thermal power generating unit. When the feedwater pump steam turbine is in normal operation, the exhaust steam of the intermediate pressure cylinder of the large steam turbine can meet the operating requirements of the feedwater pump steam turbine.

[0003] When the thermal power unit needs to operate at a low operating condition for peak load regulation, the water pump turbine also needs to operate at a low operating condition. Correspondingly, the steam source pressure required for the feedwater pump turbine increases. At this time, the exhaust steam of the medium-pressure cylinder of the large steam turbine needs to be switched to the exhaust steam of the high-pressure cylinder to provide power for the feedwater pump turbine. If the exhaust steam of the medium-pressure cylinder is directly switched to the exhaust steam of the high-pressure cylinder, there will be a large disturbance in the switching process of the two pressure levels of steam, and the feedwater pump turbine will experience a large fluctuation, causing the feedwater flow of the feedwater pump to fluctuate greatly, which will cause the thermal power unit to trip. If the exhaust steam of the high-pressure cylinder is first reduced in pressure and then combined with the exhaust steam of the medium-pressure cylinder, although the fluctuation of the feedwater pump is reduced, it will cause the heat energy of the exhaust steam of the high-pressure cylinder to be wasted. Utility Model Content

[0004] An object of the present disclosure is to provide a steam source system for a steam turbine to at least partially solve the problems existing in the related art.

[0005] In order to achieve the above-mentioned objectives, the present disclosure provides a first steam source, a second steam source and a mixing device, wherein the first steam source is respectively connected to a steam inlet of a steam turbine and a first steam inlet of the mixing device, the second steam source is connected to the second steam inlet of the mixing device, the mixing device is used to mix the steam of the first steam source and the steam of the second steam source, the steam outlet of the mixing device is connected to the steam inlet of the steam turbine, and is used to supply the mixed steam to the steam turbine, wherein the steam pressure of the second steam source is greater than the steam pressure of the first steam source.

[0006] Optionally, the steam source system includes a first pipeline, one end of which is connected to the first steam source, and the other end of which is used to communicate with the steam inlet of the steam turbine.

[0007] Optionally, the steam source system further includes:

[0008] a second pipeline, one end of which is connected to the first pipeline, and the other end of which is connected to the first steam inlet;

[0009] a third pipeline, one end of which is connected to the first pipeline, and the other end of which is connected to the steam outlet; and

[0010] The first on-off valve is arranged on the first pipeline and located between the second pipeline and the third pipeline.

[0011] Optionally, a second on-off valve is provided on the second pipeline, and a third on-off valve is provided on the third pipeline.

[0012] Optionally, a one-way valve is provided on the second pipeline, and the one-way valve is configured to only allow steam in the second pipeline to flow into the first steam inlet.

[0013] Optionally, a pressure relief valve is also provided on the third pipeline.

[0014] Optionally, the steam source system further includes a fourth pipeline, one end of the fourth pipeline is connected to the second steam source, and the other end of the fourth pipeline is connected to the second steam inlet, and a fourth on-off valve is further provided on the fourth pipeline.

[0015] Optionally, the mixing device is a steam ejector, and the steam ejector comprises:

[0016] A mixing chamber is provided with the first steam inlet and the steam outlet,

[0017] The Laval nozzle is provided with the second steam inlet for spraying the steam of the second steam source into the mixing chamber at high speed, so that the steam of the first steam source and the steam of the second steam source are mixed in the mixing chamber.

[0018] Optionally, the steam source system further includes a pressure transmitter and an actuator, wherein the pressure transmitter is used to detect the steam pressure between the steam outlet and the steam inlet of the steam turbine, and the actuator is used to adjust the opening of the Laval nozzle based on the steam pressure data detected by the pressure transmitter.

[0019] Optionally, a flow sensor for detecting steam flow is further provided between the first steam source and the steam inlet of the steam turbine.

[0020] Through the above technical solution, when the feedwater pump turbine is in normal operation, the first steam source with lower pressure can be directly supplied to the feedwater pump turbine through the steam inlet of the turbine to meet the use of the feedwater pump turbine. When the feedwater pump turbine is switched to low operating condition operation due to peak load operation, the first steam source and the second steam source can form mixed steam in the mixing device, and the pressure of the mixed steam is between the first steam source and the second steam source to meet the use of the feedwater pump turbine. For the feedwater pump turbine, the fluctuation of switching the power from the first steam source to the mixed steam is smaller than the fluctuation of directly switching the power from the first steam source to the second steam source, which further reduces the fluctuation of the feedwater pump. At the same time, the mixed steam is formed by using the pressure of the second steam source in the first steam source, instead of directly reducing the pressure of the second steam source, so the heat energy of the second steam source will not be wasted, and the first steam source is further utilized.

[0021] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0023] Figure 1 Schematic diagram of a steam source system for a steam turbine provided in accordance with an exemplary embodiment of the present disclosure.

[0024] Description of Reference Numerals

[0025] 1-first steam source, 2-second steam source, 3-mixing device, 31-mixing chamber, 32-Laval nozzle, 33-first steam inlet, 34-second steam inlet, 35-steam outlet, 4-first pipeline, 41-first on-off valve, 5-second pipeline, 51-second on-off valve, 52-check valve, 6-third pipeline, 61-third on-off valve, 62-pressure relief valve, 7-fourth pipeline, 71-fourth on-off valve, 81-pressure transmitter, 82-actuator, 83-flow sensor, 9-steam turbine. DETAILED DESCRIPTION

[0026] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0027] In the present disclosure, unless otherwise stated, the directional words used generally refer to the orientation of the relevant components in the actual use state. "Inside and outside" can refer to the inside and outside of the outline of the corresponding component or its location inside or outside the environment, depending on the specific context. In addition, when the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The terms "first", "second, third, fourth", etc. used in the present disclosure are to distinguish one element from another and do not have order or importance.

[0028] The feedwater pump steam turbine is a special type of steam turbine 9 in a thermal power generating unit. Its main function is to drive the feedwater pump, provide the boiler with feedwater of sufficient pressure, provide the boiler with necessary feedwater circulation, and ensure the continuous and stable operation of the boiler. Since the feedwater pump needs to work under high pressure and large flow, it is not cost-effective to directly use an electric motor to drive the feedwater pump in terms of economy and efficiency. Therefore, a feedwater pump steam turbine is usually used to drive the feedwater pump in a thermal power generating unit. The steam source of the feedwater pump steam turbine is generally provided by other large steam turbines in the thermal power unit. When the thermal power unit is in normal operation, the exhaust steam of the medium-pressure cylinder of the large steam turbine can meet the normal operation requirements of the feedwater pump steam turbine.

[0029] When the thermal power unit needs to operate at a low operating condition for peak load regulation, the feedwater pump turbine also needs to operate at a low operating condition. Correspondingly, the steam source pressure required for the feedwater pump turbine increases. At this time, it is necessary to switch the exhaust steam of the medium-pressure cylinder of the large steam turbine 9 to the exhaust steam of the high-pressure cylinder to provide a higher-pressure steam source for the feedwater pump turbine. If the exhaust steam of the medium-pressure cylinder is directly switched to the exhaust steam of the high-pressure cylinder, there will be a large disturbance in the switching process of the two pressure levels of steam, and the feedwater pump turbine will experience a large fluctuation, which will further cause the feedwater flow of the feedwater pump to fluctuate greatly, and then cause the thermal power unit to trip. If the exhaust steam of the high-pressure cylinder is first reduced in pressure and then combined with the exhaust steam of the medium-pressure cylinder, although the fluctuation of the feedwater pump is reduced, it will cause the heat energy of the exhaust steam of the high-pressure cylinder to be wasted.

[0030] like Figure 1 As shown, the present disclosure provides a steam source system for a steam turbine 9, comprising a first steam source 1, a second steam source 2 and a mixing device 3, wherein the first steam source 1 is connected to a steam inlet of the steam turbine 9 and a first steam inlet 33 of the mixing device 3 respectively, the second steam source 2 is connected to a second steam inlet 34 of the mixing device 3, the mixing device 3 is used for mixing the steam of the first steam source 1 and the steam of the second steam source 2, the steam outlet 35 of the mixing device 3 is connected to the steam inlet of the steam turbine 9, and is used for supplying the mixed steam to the steam turbine 9, wherein the steam pressure of the second steam source 2 is greater than the steam pressure of the first steam source 1.

[0031] Through the above technical solution, when the feedwater pump turbine is in normal operation, the first steam source 1 with a lower pressure can be directly supplied to the feedwater pump turbine through the steam inlet of the turbine to meet the use of the feedwater pump turbine. When the feedwater pump turbine is switched to low-operation operation due to peak load operation, the first steam source 1 and the second steam source 2 can form mixed steam in the mixing device 3, and the pressure of the mixed steam is between the first steam source 1 and the second steam source 2 to meet the use of the feedwater pump turbine. For the feedwater pump turbine, the fluctuation of switching the power from the first steam source 1 to the mixed steam is smaller than the fluctuation of directly switching the power from the first steam source 1 to the second steam source 2, which further reduces the fluctuation of the feedwater pump. At the same time, the mixed steam is formed by using the pressure of the first steam source 1 and the second steam source 2, instead of directly reducing the pressure of the second steam source 2, so the heat energy of the second steam source 2 will not be wasted, and the first steam source 1 is further utilized.

[0032] In the present disclosure, the first steam source 1 may be steam discharged from the intermediate pressure cylinder of the above-mentioned large steam turbine 9, and the second steam source 2 may be steam discharged from the high pressure cylinder of the above-mentioned large steam turbine 9. The mixed steam may be formed by mixing the steam discharged from the intermediate pressure cylinder and the steam discharged from the high pressure cylinder.

[0033] In some embodiments, the steam source system may include a first pipeline 4, one end of which is connected to the first steam source 1, and the other end is used to communicate with the steam inlet of the steam turbine 9. The first pipeline 4 can be adaptively designed to extend the path according to the position of the feedwater pump turbine and the position of the first steam source 1, and the steam source system has a higher degree of freedom in layout. At the same time, the first pipeline 4 can be buried underground, overhead or laid along the wall, reducing the space occupied.

[0034] The steam source system may further include a second pipeline 5, a third pipeline 6 and a first on-off valve 41. One end of the second pipeline 5 is connected to the first pipeline 4, and the other end is connected to the first steam inlet 33; one end of the third pipeline 6 is connected to the first pipeline 4, and the other end is connected to the steam outlet 35; the first on-off valve 41 is arranged on the first pipeline 4 and is located between the second pipeline 5 and the third pipeline 6. When the first on-off valve 41 blocks the first pipeline 4 located between the second pipeline 5 and the third pipeline 6, the steam of the first steam source 1 can enter the mixing device 3 through the second pipeline 5, and mix with the steam of the second steam source 2 in the mixing device 3, and the mixed steam returns to the first pipeline 4 through the first steam pipeline and provides power for the feedwater pump turbine through the first pipeline 4. When the feedwater pump turbine needs to operate at a low operating condition, the first on-off valve 41 is used to open or close the first pipeline 4. When the first pipeline 4 is closed, the steam from the first steam source 1 is prevented from directly providing power to the feedwater pump turbine without mixing with the steam from the second steam source 2. The second pipeline 5 and the third pipeline 6 can be designed to extend according to the position of the mixing device 3 and the position of the first pipeline 4, and the steam source system has a higher degree of freedom in layout. At the same time, it can be buried underground, suspended or laid along the wall, reducing the space occupied.

[0035] A second on-off valve 51 may be provided on the second pipeline 5, and a third on-off valve 61 may be provided on the third pipeline 6. The second on-off valve 51 is used to open or close the second pipeline 5, and the third on-off valve 61 is used to open or close the third pipeline 6. When the second pipeline 5 and the third pipeline 6 are closed, the connection between the first pipeline 4 and the mixing device 3 is cut off, so as to prevent the steam of the first steam source 1 from entering the mixing device 3 when the feedwater pump turbine is in normal operation. At the same time, the second on-off valve 51 and the third on-off valve 61 can be arranged as close to the first pipeline 4 as possible, so that the steam in the first pipeline 4 will enter the second pipeline 5 and the third pipeline 6 as little as possible, so as to avoid the waste of steam.

[0036] Since the steam pressure of the second steam source 2 is greater than the steam pressure of the first steam source 1, when the steam of the first steam source 1 and the steam of the second steam source 2 enter the mixing device 3 at the same time, the steam of the second steam source 2 may enter the second pipeline 5 through the first steam inlet 33, affecting the flow of the steam of the first steam source 1 in the second pipeline 5. At this time, a one-way valve 52 may be provided on the second pipeline 5, and the one-way valve 52 is configured to only allow the steam in the second pipeline 5 to flow into the first steam inlet 33, so as to prevent the steam of the second steam source 2 from flowing out of the first steam inlet 33 and flowing in the second pipeline 5.

[0037] A pressure relief valve 62 may also be provided on the third pipeline 6. When the steam from the first steam source 1 and the steam from the second steam source 2 are not mixed sufficiently, the pressure of the mixed steam may increase. When the pressure in the third pipeline 6 exceeds a preset safety value, the pressure relief valve 62 opens to release excess steam, thereby reducing the pressure in the third pipeline 6 to a safe range, preventing the third pipeline or the steam source system from being damaged or ruptured due to overpressure, and ensuring the safety of the steam source system when the steam source system is damaged.

[0038] The steam source system may also include a fourth pipeline 7, one end of which is connected to the second steam source 2, and the other end of which is connected to the second steam inlet 34. A fourth on-off valve 71 is also provided on the fourth pipeline 7. The fourth pipeline 7 is used to open or close the fourth pipeline 7. When the second steam source 2 is not in use, that is, when the feedwater pump turbine is in normal operation, the steam of the second steam source 2 is prevented from entering the mixing device 3 and being wasted. The fourth pipeline 7 can be adaptively designed to extend the path according to the position of the mixing device 3 and the position of the second steam source 2, and the steam source system has a higher degree of freedom in layout. At the same time, the fourth pipeline 7 can be buried underground, suspended or laid along the wall, reducing the occupation of space.

[0039] The mixing device 3 may be a steam ejector, which includes a mixing chamber 31 and a Laval nozzle 32. The mixing chamber 31 is provided with a first steam inlet 33 and a steam outlet 35, and the Laval nozzle 32 is provided with a second steam inlet 34, which is used to spray the steam of the second steam source 2 into the mixing chamber 31 at high speed, so that the steam of the first steam source 1 and the steam of the second steam source 2 are mixed in the mixing chamber 31. The steam ejector is a device that does not require an electric device to drive, and it is a simple mechanical structure that works based on the principle of fluid mechanics. The steam of the second steam source 2 is accelerated through the Laval nozzle 32 to form a high-speed jet, and a low-pressure area is generated inside the mixing chamber 31, thereby ejecting and compressing the steam of the first steam source 1. In this process, the potential energy of the steam of the second steam source 2 can be converted into kinetic energy. The steam of the first steam source 1 and the steam of the second steam source 2 can be mixed in the mixing chamber 31 without external power input, and do not rely on motors or other external power sources, which reduces the power required when the steam source system is used and reduces costs.

[0040] The steam source system may also include a pressure transmitter 81 and an actuator 82. The pressure transmitter 81 is used to detect the steam pressure between the steam outlet 35 and the steam inlet of the steam turbine 9. The actuator 82 is used to adjust the opening of the Laval nozzle 32 based on the steam pressure data detected by the pressure transmitter 81. The pressure transmitter 81 is a sensor device that can measure the pressure of gas, liquid or steam, and convert this pressure information into a standard electrical signal output for remote monitoring, recording or control. The actuator 82 is an indispensable and important component in the automatic control system, and can receive the control signal sent by the controller to adjust the size of the opening of the Laval nozzle 32. The actuator 82 can be divided into three categories according to its energy form: pneumatic, hydraulic, and electric. In the present application, the actuator 82 can be a pneumatic actuator 82, a hydraulic actuator 82, or an electric actuator 82, which can be adaptively selected according to the use of the steam source system. The feed pump steam turbine will also have certain fluctuations when operating at low operating conditions. By adjusting the opening of the Laval nozzle 32 through the pressure transmitter 81 and the actuator 82, the pressure of the mixed steam can be adjusted so that the mixed steam can adapt to the fluctuations of the feed pump steam turbine when operating at low operating conditions.

[0041] A flow sensor 83 for detecting steam flow can also be provided between the first steam source 1 and the steam inlet of the steam turbine 9. Monitoring steam flow can help prevent equipment overload or lack of flow, avoid equipment damage or production accidents caused by abnormal flow, and ensure safe operation. At the same time, from the change in steam flow, the operator can judge the use status of the steam source system. Taking the reduction in steam flow as an example, it may be caused by steam liquefaction due to the long pipeline. In addition, some abnormal flow changes may indicate blockage, leakage or other faults in the pipeline in the steam source system. The flow sensor 83 can remind the operator to maintain the steam source system in time.

[0042] The outer surfaces of the first pipeline 4, the second pipeline 5, the third pipeline 6 and the fourth pipeline 7 mentioned above may be covered with a heat preservation layer to ensure the temperature of the steam and prevent the steam from re-liquefying. At the same time, the inner wall surfaces of the first pipeline 4, the second pipeline 5, the third pipeline 6 and the fourth pipeline 7 mentioned above may be provided with an anti-corrosion coating to prevent the moisture in the steam from corroding the pipe wall and extend the service life of the pipeline.

[0043] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0045] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A steam source system for a steam turbine, characterized in that: The invention comprises a first steam source, a second steam source and a mixing device, wherein the first steam source is connected to a steam inlet of a steam turbine and a first steam inlet of the mixing device respectively, the second steam source is connected to a second steam inlet of the mixing device, the mixing device is used for mixing steam from the first steam source and steam from the second steam source, the steam outlet of the mixing device is connected to the steam inlet of the steam turbine, and is used for supplying the mixed steam to the steam turbine, wherein the steam pressure of the second steam source is greater than the steam pressure of the first steam source.

2. The steam source system for a steam turbine according to claim 1, characterized in that: The steam source system comprises a first pipeline, one end of which is connected to the first steam source, and the other end of which is used to be connected to the steam inlet of the steam turbine.

3. The steam source system for a steam turbine according to claim 2, characterized in that: The steam source system also includes: a second pipeline, one end of which is connected to the first pipeline, and the other end of which is connected to the first steam inlet; a third pipeline, one end of which is connected to the first pipeline, and the other end of which is connected to the steam outlet; and The first on-off valve is arranged on the first pipeline and located between the second pipeline and the third pipeline.

4. The steam source system for a steam turbine according to claim 3, characterized in that: The second pipeline is provided with a second on-off valve, and the third pipeline is provided with a third on-off valve.

5. The steam source system for a steam turbine according to claim 3, characterized in that: The second pipeline is provided with a one-way valve, and the one-way valve is configured to only allow the steam in the second pipeline to flow into the first steam inlet.

6. The steam source system for a steam turbine according to claim 3, characterized in that: The third pipeline is also provided with a pressure relief valve.

7. The steam source system for a steam turbine according to claim 1, characterized in that: The steam source system further includes a fourth pipeline, one end of which is connected to the second steam source, and the other end of which is connected to the second steam inlet. A fourth on-off valve is also provided on the fourth pipeline.

8. The steam source system for a steam turbine according to claim 1, characterized in that: The mixing device is a steam ejector, and the steam ejector comprises: A mixing chamber is provided with the first steam inlet and the steam outlet, The Laval nozzle is provided with the second steam inlet for spraying the steam of the second steam source into the mixing chamber at high speed, so that the steam of the first steam source and the steam of the second steam source are mixed in the mixing chamber.

9. The steam source system for a steam turbine according to claim 8, characterized in that: The steam source system also includes a pressure transmitter and an actuator. The pressure transmitter is used to detect the steam pressure between the steam outlet and the steam inlet of the steam turbine. The actuator is used to adjust the opening of the Laval nozzle based on the steam pressure data detected by the pressure transmitter.

10. The steam source system for a steam turbine according to claim 1, characterized in that: A flow sensor for detecting steam flow is also provided between the first steam source and the steam inlet of the steam turbine.

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