A method for optimizing steam turbine low-pressure cylinder exhaust flow field based on high-pressure jet water film

Abstract

This invention discloses a method for optimizing the exhaust flow field of a steam turbine low-pressure cylinder based on a high-pressure jet water film, comprising the following steps: establishing a steam turbine low-pressure cylinder exhaust model, performing mesh generation and flow field simulation analysis on the model; obtaining an optimization scheme for the exhaust flow field of the steam turbine low-pressure cylinder based on the calculation results; designing a layout scheme for the water film jet device based on the optimization scheme and completing its on-site installation; performing on-site flow field optimization under varying operating conditions of the steam turbine to ensure that the steam turbine vacuum is always maintained at its optimal state; combining the on-site flow field optimization data, obtaining the jet data of the water film jet device under optimal vacuum conditions during a series of varying operating conditions of the steam turbine, and obtaining a full-condition flow field optimization control strategy for the steam turbine, thus achieving full-process optimization of the steam turbine exhaust flow field. This invention uses a water film jet device to generate a high-pressure jet water film, and the spray area, spray flow rate, and spray angle of the high-pressure jet water film can be adjusted to achieve full-process optimization of the steam turbine exhaust flow field.

Description

Technical Field

[0001] This invention belongs to the field of turbine technology, specifically relating to a method for optimizing the low-pressure cylinder exhaust flow field of a steam turbine based on a high-pressure jet water film. Background Technology

[0002] Reducing turbine exhaust pressure is one of the most direct and effective methods for power plants to improve unit economy and achieve energy conservation and emission reduction. In addition to strengthening operation and maintenance management, optimizing the turbine exhaust passage and adding flow equalization and guiding devices with specific arrangements can make the distribution of turbine exhaust steam in the condenser cooling tube bundle more rational, fully utilize the effective heat exchange area of ​​the condenser, improve the overall performance of the condenser, and ultimately achieve the goal of increasing vacuum and reducing exhaust pressure. Traditional methods for optimizing the turbine exhaust pressure flow field, such as... Figure 1 As shown, the following defects exist:

[0003] 1. In traditional methods, the guide vanes are fixed and can only be optimized for a certain operating condition or a certain range of operating conditions of the steam turbine. However, in actual operation, the steam turbine often operates under a wide range of varying operating conditions. As the operating conditions change, the exhaust flow field of the steam turbine will change significantly. Traditional guide vanes are difficult to produce a guiding effect after deviating from the design operating conditions, and sometimes they will even increase the resistance.

[0004] 2. In traditional methods, design and calculation are based on simulation results. Although high-level models and simulation processes can simulate real operating conditions to the greatest extent, there will still be deviations from the actual site. The exhaust flow field of a steam turbine is relatively complex. After the flow field optimization process is completed, since the installed guide vanes are fixed, there is a lack of debugging and adjustment means. Once a deviation in the on-site operating state is found that the design needs to be corrected, the original guide vanes can only be removed and reinstalled, which involves a large workload and lacks flexibility. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the purpose of this invention is to provide a method for optimizing the low-pressure cylinder exhaust flow field of a steam turbine based on a high-pressure jet water film.

[0006] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0007] A method for optimizing the low-pressure cylinder exhaust steam flow field of a steam turbine based on high-pressure jet water film includes the following steps:

[0008] First, a low-pressure cylinder exhaust model of the steam turbine is established, and the low-pressure cylinder exhaust model is meshed and the flow field is simulated and analyzed.

[0009] Subsequently, based on the flow field simulation analysis results, the flow field optimization scheme of the exhaust section of the low-pressure cylinder of the steam turbine was obtained. Then, based on the flow field optimization scheme, the layout scheme of the water film jet device was designed and the on-site installation was completed. On-site flow field optimization was carried out under the variable operating conditions of the steam turbine to keep the steam turbine vacuum at the best state.

[0010] Finally, by combining the on-site flow field optimization data, the jet data of the water film jet device under the optimal vacuum conditions of a series of variable operating conditions of the steam turbine were obtained, thereby obtaining the steam turbine full-condition flow field optimization control strategy and realizing the full-process optimization of the steam turbine exhaust flow field.

[0011] Furthermore, the steps for establishing a low-pressure cylinder exhaust model of the steam turbine, and performing mesh generation and flow field simulation analysis on the low-pressure cylinder exhaust model include:

[0012] 1) Collect structural drawings and corresponding thermodynamic characteristic data of the exhaust section of the low-pressure cylinder of the steam turbine;

[0013] 2) Use the structural drawings obtained in step 1) to establish the corresponding low-pressure cylinder exhaust model, and use the thermodynamic characteristic data to perform mesh generation and flow field simulation analysis on the low-pressure cylinder exhaust model.

[0014] Furthermore, the flow field optimization scheme for the exhaust section of the low-pressure cylinder of the steam turbine includes designing the size, shape, installation position, and angle of the guide vane.

[0015] Furthermore, the water film jet device includes a jet nozzle body, with rotating connectors at opposite ends of the jet nozzle body. The rotating connectors can drive the jet nozzle body to rotate. The jet nozzle body is provided with a water inlet and a water film nozzle communicating with its interior. Water is sprayed through the water film nozzle to form a high-pressure jet water film. The jet pressure of the high-pressure jet water film is much greater than the exhaust pressure of the steam turbine. The spray area, spray flow rate, and spray angle of the high-pressure jet water film are adjustable.

[0016] Furthermore, the jet pressure of the high-pressure jet water film is 1.5MPa to 2MPa.

[0017] Furthermore, the jet spray gun body has a water inlet at one end and is sealed at the other end.

[0018] Furthermore, when designing the layout scheme of the water film jet device according to the flow field optimization scheme, the spray area and spray flow rate of the high-pressure jet water film are adjusted by controlling the inlet water pressure and inlet water flow rate of the water film jet device, and the spray angle of the high-pressure jet water film is adjusted by rotating the rotating connector of the water film jet device. This ensures that the shape of the high-pressure jet water film is similar to that of the guide plate designed in the flow field optimization scheme of the exhaust section of the low-pressure cylinder of the steam turbine, thereby achieving the effect of flow field optimization.

[0019] Furthermore, the steps for optimizing the on-site flow field under varying turbine operating conditions to maintain the turbine vacuum at its optimal state include:

[0020] Under varying operating conditions of the steam turbine, the spray angle, spray area, and spray flow rate of the high-pressure jet water film of the water film jet device are continuously adjusted online. Specifically, the spray area and spray flow rate of the high-pressure jet water film are continuously adjusted online in real time by controlling the inlet water pressure and inlet water flow rate of the water film jet device, and the spray angle of the high-pressure jet water film is continuously adjusted by rotating the rotating connector of the water film jet device, so that the steam turbine vacuum is always maintained in the optimal state.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention discloses a method for optimizing the exhaust flow field of a steam turbine low-pressure cylinder based on a high-pressure jet water film. Unlike the traditional method of installing a fixed guide plate in the low-pressure cylinder channel after flow field optimization calculation, this invention uses a water film jet device to generate a high-pressure jet water film, replacing the traditional fixed guide device. Unlike the traditional fixed guide device, which can only optimize the flow field for certain specific operating conditions, this invention can adjust the spray area and spray flow rate of the high-pressure jet water film by controlling the inlet water pressure and inlet water flow rate of the water film jet device. It can also adjust the spray angle of the high-pressure jet water film by rotating the rotating connector of the water film jet device, thus achieving full-process optimization of the steam turbine exhaust flow field. Attached Figure Description

[0023] Figure 1 A flowchart of the existing method for optimizing the exhaust pressure flow field of a steam turbine.

[0024] Figure 2 This is a flowchart of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure of the water film jet device of the present invention. Detailed Implementation

[0026] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0027] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0028] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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 this invention.

[0029] like Figure 2-3 As shown, a method for optimizing the low-pressure cylinder exhaust steam flow field of a steam turbine based on a high-pressure jet water film includes the following steps:

[0030] 1) Collect structural drawings and corresponding thermodynamic characteristic data of the low-pressure cylinder exhaust section of the target steam turbine unit;

[0031] 2) Using the structural drawings obtained in step 1), establish the corresponding low-pressure cylinder exhaust model. Through the thermodynamic characteristic data of the low-pressure cylinder exhaust, perform mesh generation and flow field numerical simulation analysis on the low-pressure cylinder exhaust model.

[0032] 3) Based on the numerical simulation analysis results of the flow field obtained in step 2), the flow field optimization scheme of the low-pressure cylinder exhaust section of the unit is obtained, including the design of the size, shape, installation position and angle of the guide plate. By changing the flow field of the low-pressure cylinder exhaust, the heat exchange efficiency of the low-pressure exhaust is maximized and the unit vacuum is reduced.

[0033] 4) Based on the flow field optimization scheme obtained in step 3), design the layout scheme of the water film jet device, and set the jet flow rate, jet area, jet angle, etc. of the high-pressure jet water film of the water film jet device so that the obtained high-pressure jet water film is similar to the shape of the guide plate designed in the flow field optimization scheme, so as to achieve the effect of flow field optimization.

[0034] The water film jet device designed in this invention can rotate and control the jet flow rate, thus overcoming the drawbacks of traditional guide plate installation errors;

[0035] 5) After the water film jet device is installed according to the flow field optimization scheme, further flow field optimization tests are carried out. Under the variable operating conditions of the steam turbine, the spray angle, area and flow rate of the high-pressure jet water film of the water film jet device are continuously adjusted online to keep the steam turbine vacuum at the best state. This can be understood as the lowest vacuum state under the current steam flow rate and circulating cooling water flow rate. Under the same external conditions, the lower the steam turbine vacuum, the better.

[0036] 6) By combining field test data, the jet angle and flow rate data under the optimal vacuum conditions of a series of variable operating conditions of the steam turbine are obtained, thereby obtaining the steam turbine full-condition flow field optimization control strategy.

[0037] In step 4), the water film jet device includes a jet gun body 2. One end of the jet gun body 2 is a water inlet, and the other end is sealed. A water film nozzle 3 is provided on the jet gun body 2. Rotary connectors 4 are respectively provided at the opposite ends of the jet gun body 2. The rotary connectors 4 can rotate 360 ​​degrees clockwise. Rotating the rotary connectors 4 can control the spray angle of the jet gun body 2. High-pressure water flows into the jet gun body 2 from the water inlet and can be ejected at high speed through the water film nozzles 3 to form a high-pressure jet water film. The area of ​​the high-pressure jet water film can be controlled by controlling the water inlet pressure and water inlet flow rate.

[0038] The exhaust pressure of a conventional condensing steam turbine is approximately 7–8 kPa. The water source for the water film jet device of this invention is taken from the condensate pump outlet of the unit, with a jet pressure of approximately 1.5 MPa–2 MPa. The inlet flow rate is controlled by a regulating valve to control the high-pressure jet water film spray area. Because the high-pressure jet water film pressure is much higher than the turbine exhaust pressure, the steam cannot break through the high-pressure jet water film. As long as the inlet pressure is maintained, a high-pressure jet water film can be continuously formed, thus maintaining a good guiding effect. As the turbine operating conditions change, the turbine exhaust flow field also changes. At this time, by comprehensively controlling the jet angle and jet area of ​​the high-pressure jet water film, the spray parameters of the high-pressure jet water film can be adjusted at any time to always adapt to the changes in the turbine exhaust flow field, achieving a good guiding effect.

[0039] In step 4), when designing the layout scheme of the water film jet device according to the flow field optimization scheme, the spray area and spray flow rate of the high-pressure jet water film are adjusted by controlling the inlet water pressure and inlet water flow rate of the water film jet device, and the spray angle of the high-pressure jet water film is adjusted by rotating the rotating connector of the water film jet device, so as to ensure that the shape of the high-pressure jet water film is similar to that of the guide plate designed in the flow field optimization scheme of the low-pressure cylinder exhaust section of the steam turbine, thereby achieving the effect of flow field optimization.

[0040] In step 5), under the variable operating conditions of the steam turbine, the spray area and spray flow of the high-pressure jet water film are continuously adjusted online in real time by controlling the inlet water pressure and inlet water flow of the water film jet device, and the spray angle of the high-pressure jet water film is continuously adjusted by rotating the rotating connector of the water film jet device, so that the steam turbine vacuum is always maintained in the optimal state.

[0041] Compared with the prior art, the present invention has at least the following technical effects:

[0042] Traditional low-pressure cylinder exhaust flow field optimization methods stop at step 3). The turbine exhaust flow field is quite complex. After completing the flow field optimization process, the traditional low-pressure cylinder exhaust flow field optimization method lacks debugging and adjustment means because the installed guide vanes are fixed. Once a deviation in the on-site operating state is found that the design needs to be corrected, the original guide vanes can only be removed and reinstalled, which is a lot of work and lacks flexibility. This invention solves the above technical problems. Using the low-pressure cylinder exhaust flow field optimization method of this invention, the low-pressure cylinder exhaust flow field optimization under all operating conditions can be achieved, which is difficult to achieve with traditional methods.

[0043] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0044] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for optimizing the flow field of the exhaust steam of the low-pressure cylinder of a steam turbine based on a high-pressure water jet film, characterized in that, Includes the following steps: First, a low-pressure cylinder exhaust model of the steam turbine is established, and the low-pressure cylinder exhaust model is meshed and the flow field is simulated and analyzed. Subsequently, based on the flow field simulation analysis results, the flow field optimization scheme of the exhaust section of the low-pressure cylinder of the steam turbine was obtained. Then, based on the flow field optimization scheme, the layout scheme of the water film jet device was designed and the on-site installation was completed. On-site flow field optimization was carried out under the variable operating conditions of the steam turbine to keep the steam turbine vacuum at the best state. Finally, by combining the on-site flow field optimization data, the jet data of the water film jet device under the optimal vacuum conditions of a series of variable operating conditions of the steam turbine were obtained, thereby obtaining the steam turbine full-condition flow field optimization control strategy and realizing the full-process optimization of the steam turbine exhaust flow field. The steps for establishing a steam turbine low-pressure cylinder exhaust model, including mesh generation and flow field simulation analysis, include: 1) Collect structural drawings and corresponding thermodynamic characteristic data of the exhaust section of the low-pressure cylinder of the steam turbine; 2) Use the structural drawings obtained in step 1) to establish the corresponding low-pressure cylinder exhaust model, and use the thermodynamic characteristic data to perform mesh generation and flow field simulation analysis on the low-pressure cylinder exhaust model; The water film jet device includes a jet nozzle body, with rotating connectors at opposite ends of the jet nozzle body. The rotating connectors can drive the jet nozzle body to rotate. The jet nozzle body is provided with a water inlet and a water film nozzle communicating with its interior. Water is sprayed through the water film nozzle to form a high-pressure jet water film. The jet pressure of the high-pressure jet water film is much greater than the exhaust pressure of the steam turbine. The spray area, spray flow rate, and spray angle of the high-pressure jet water film are adjustable. The jet pressure of the high-pressure jet water film is 1.5MPa~2MPa; When designing the layout scheme of the water film jet device according to the flow field optimization scheme, the spray area and spray flow of the high-pressure jet water film are adjusted by controlling the inlet water pressure and inlet water flow of the water film jet device, and the spray angle of the high-pressure jet water film is adjusted by rotating the rotating connector of the water film jet device. This ensures that the shape of the high-pressure jet water film is similar to that of the guide plate designed in the flow field optimization scheme of the exhaust section of the low-pressure cylinder of the steam turbine, so as to achieve the effect of flow field optimization. The steps for optimizing the flow field in the steam turbine under varying operating conditions to maintain the turbine vacuum at its optimal state include: Under the variable operating conditions of the steam turbine, the spray area and spray flow of the high-pressure jet water film are continuously adjusted online in real time by controlling the inlet water pressure and inlet water flow of the water film jet device, and the spray angle of the high-pressure jet water film is continuously adjusted by rotating the rotating connector of the water film jet device, so that the steam turbine vacuum is always maintained in the optimal state. The flow field optimization scheme for the exhaust section of the low-pressure cylinder of the steam turbine includes designing the size, shape, installation position, and angle of the guide vane; The jet spray gun body has a water inlet at one end and is sealed at the other end.

Images