A steam turbine generator unit lubricating oil system leakage prevention optimization method and system

Abstract

The application discloses a kind of steam turbine generator set lubricating oil system leak-proof optimization method and system, it is related to steam turbine generator set auxiliary system technical field, the method includes: establishing lubricating oil oil supply system simulation model and calculating the oil supply flow under different oil supply pressure;Based on the principle of mass conservation, the oil supply flow calculated is input, the mathematical model of the flow state in the return oil pipe is established, and the liquid level height proportion of each pipe section of the return oil pipe is obtained by solving;The blocked pipe section of negative pressure transmission is identified and the pipe diameter is optimized in combination with the liquid level height proportion of each pipe section of the return oil pipe and the measured data;Establish oil baffle CFD analysis model, analyze the leakage rate under different negative pressure and installation gap to determine the best operating negative pressure and optimal installation gap;According to optimal pipe diameter, best negative pressure and optimal gap, generate leak-proof overall optimization scheme.The application can realize the collaborative optimization of return oil pipeline, bearing box negative pressure and oil baffle gap, and fundamentally solves the lubricating oil leakage problem.

Description

Technical Field

[0001] This invention relates to the field of auxiliary systems technology for steam turbine generator sets, and in particular to an optimization method and system for preventing leakage in the lubricating oil system of a steam turbine generator set. Background Technology

[0002] The lubrication system of a steam turbine generator set is a key auxiliary system for the safe and stable operation of the unit. Its main function is to provide lubricating and cooling oil to the bearings of the unit and to return the lubricating oil to the main oil tank through the oil return system.

[0003] Currently, lubricating oil leakage is a common problem during the normal operation of steam turbine generator sets, especially leakage from the external oil baffle. This not only causes lubricating oil loss but also affects the operating environment and equipment safety of the steam turbine generator set. How to effectively prevent lubricating oil leakage is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] In view of this, the present invention provides an optimization method and system for preventing leakage in the lubrication oil system of a steam turbine generator set, to solve the problem of lubrication oil leakage in the lubrication oil system of a steam turbine generator set. The technical solution is as follows:

[0005] The first aspect of this invention provides a method for optimizing the anti-leakage of a steam turbine generator set lubrication oil system, comprising:

[0006] A simulation model of the lubricating oil supply system of a steam turbine generator set is established, and the oil supply flow rate of each bearing under different oil supply pressures is calculated based on the simulation model.

[0007] Based on the principle of mass conservation, a mathematical model of the flow state in the return oil pipe is established using the calculated oil supply flow rate as input. By solving the mathematical model of the flow state in the return oil pipe, the proportion of liquid level height in each section of the return oil pipe under different oil supply pressures is obtained. Based on the obtained proportion of liquid level height and combined with the on-site bearing box pressure measurement data, the return oil pipe section where negative pressure transmission is obstructed is identified.

[0008] Using a preset liquid level height ratio as the optimization target, the pipe diameter of the return oil pipe section where negative pressure transmission is obstructed is optimized to obtain the optimal pipe diameter of the return oil pipe section where negative pressure transmission is obstructed.

[0009] A computational fluid dynamics (CFD) analysis model for the oil baffle is established. Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances is analyzed. Based on the lubricating oil leakage rate obtained from the analysis, the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle are determined.

[0010] Based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, an overall optimization scheme for preventing leakage of the lubricating oil system is generated for the purpose of optimizing the leakage prevention of the lubricating oil system.

[0011] In one possible implementation, establishing a simulation model of the turbine generator set lubricating oil supply system includes:

[0012] Based on the design drawings of the steam turbine generator set lubrication oil system, construct a three-dimensional solid model of the lubrication oil supply system.

[0013] Based on the geometric parameters provided by the three-dimensional solid model, a preliminary simulation model of the lubricating oil supply system is constructed.

[0014] The preliminary simulation model was verified using on-site measured oil supply flow data for each bearing.

[0015] If the verification passes, the preliminary simulation model is determined as the final simulation model; if the verification fails, the preliminary simulation model is modified, and the modified simulation model is re-verified using the on-site measured oil supply flow data of each bearing. If the verification passes, the modified simulation model is determined as the final simulation model.

[0016] In one possible implementation, the verification of the preliminary simulation model using field-measured oil supply flow data for each bearing includes:

[0017] Based on the preliminary simulation model, the oil supply flow rate of each bearing under different oil supply pressures is calculated, and the simulated oil supply flow rate of each bearing under different oil supply pressures is obtained.

[0018] The simulated oil supply flow rate of each bearing under different oil supply pressures is compared with the corresponding on-site measured oil supply flow rate.

[0019] If all comparison deviations are within the allowable range for engineering, the preliminary simulation model is deemed to have passed verification; otherwise, the preliminary simulation model is deemed to have failed verification.

[0020] In one possible implementation, based on the principle of mass conservation, a mathematical model of the flow state within the return oil pipe is established using the calculated oil supply flow rate as input. By solving this mathematical model, the percentage of liquid level in each section of the return oil pipe under different oil supply pressures is obtained, including:

[0021] Using the calculated oil supply flow rate as the return oil flow rate input, the driving force and resistance of the return oil pipe flow are analyzed. The driving force is the superposition of the component of fluid gravity along the pipe direction and the pressure gradient of the negative pressure fan, and the resistance is the frictional resistance along the pipe.

[0022] Based on the geometric characteristics of the tubing structure of the return oil pipe, the cross-sectional area and wetted perimeter of the return oil pipe are calculated in segments, and the balance equation of driving force and resistance is established based on the calculated cross-sectional area and wetted perimeter.

[0023] The equilibrium equation is solved numerically through iteration to obtain the percentage of liquid level in each section of the return oil pipe under different oil supply pressures.

[0024] In one possible implementation, the oil return pipe has a nested structure consisting of a lubricating oil pipe and a top shaft oil pipe inside the oil return pipe.

[0025] The geometric characteristics of the combined return oil pipe and the sleeved oil pipe structure are used to calculate the cross-sectional area and wetted perimeter of the return oil pipe in segments, including:

[0026] Based on the relationship between the liquid level and the position of the inner tube of the return oil pipe, various working conditions are defined, including: the liquid level does not contact the top shaft oil pipe, the liquid level contacts the top shaft oil pipe but is not completely submerged, the top shaft oil pipe is completely submerged but does not contact the lubricating oil pipe, the liquid level contacts the lubricating oil pipe but is not completely submerged, and the lubricating oil pipe is completely submerged.

[0027] The cross-sectional area and wetted perimeter of the return oil pipe were calculated for each of the aforementioned operating conditions.

[0028] In one possible implementation, identifying the return oil pipe section where negative pressure transmission is obstructed, based on the obtained liquid level height percentage and combined with on-site bearing box pressure measurement data, includes:

[0029] Obtain the percentage of liquid level in each return oil pipe section within the target oil supply pressure range;

[0030] The pipe section where the liquid level height ratio exceeds the preset liquid level height ratio threshold and the corresponding bearing box measured pressure is higher than the preset negative pressure benchmark or the corresponding bearing box measured pressure is in a slightly positive pressure state is identified as the return oil pipe section where negative pressure transmission is obstructed.

[0031] In one possible implementation, the step of using a preset liquid level height percentage as the optimization target to perform pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, to obtain the optimal pipe diameter for the return oil pipe section where negative pressure transmission is obstructed, includes:

[0032] From each of the pipe segments where negative pressure transmission is obstructed, the pipe segments to be optimized are determined according to the preset pipe segment selection rules;

[0033] Using the preset multi-level liquid level height ratio as the optimization target, the pipe diameter of the pipe section to be optimized is calculated to obtain the optimal pipe diameter that meets the optimization target.

[0034] In one possible implementation, the pipe segment selection rules include:

[0035] For the return branch pipe, select the inlet pipe section;

[0036] For the return oil header, pipe sections are selected according to priority order from smallest to largest pipe diameter;

[0037] Pipe sections were selected according to the priority order of oil supply flow rate from large to small, pipeline slope from small to large, and liquid level height percentage from high to low.

[0038] In one possible implementation, the optimal operating negative pressure of the bearing housing is -0.5 kPa, and the optimal installation clearance range of the oil baffle is 0.30 mm to 0.60 mm.

[0039] The second aspect of the present invention provides a leak prevention optimization system for a steam turbine generator set lubrication oil system, comprising: an oil supply simulation module, a return oil flow analysis module, a pipe diameter optimization module, an oil baffle CFD simulation module, and a leak prevention optimization scheme generation module;

[0040] The oil supply simulation module is used to establish a simulation model of the lubricating oil supply system of the steam turbine generator set, and to calculate the oil supply flow rate of each bearing under different oil supply pressures based on the simulation model.

[0041] The oil return flow analysis module is used to establish a mathematical model of the flow state in the oil return pipe based on the principle of mass conservation and the calculated oil supply flow rate as input. By solving the mathematical model of the flow state in the oil return pipe, the liquid level height ratio of each section of the oil return pipe under different oil supply pressures is obtained. Based on the obtained liquid level height ratio and combined with the on-site bearing box pressure measurement data, the oil return pipe section where negative pressure transmission is obstructed is identified.

[0042] The pipe diameter optimization module is used to perform pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, with a preset liquid level height ratio as the optimization target, to obtain the optimal pipe diameter of the return oil pipe section where negative pressure transmission is obstructed.

[0043] The oil baffle CFD simulation module is used to establish a computational fluid dynamics (CFD) analysis model of the oil baffle. Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances is analyzed. Based on the lubricating oil leakage rate obtained from the analysis, the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle are determined.

[0044] The leak prevention optimization scheme generation module is used to generate an overall leak prevention optimization scheme for the lubricating oil system based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, for the purpose of leak prevention optimization of the lubricating oil system.

[0045] The present invention provides a method for optimizing the anti-leakage of the lubricating oil system in a steam turbine generator set. Through the joint analysis of a simulation model of the oil supply system and a mathematical model of the flow state in the return oil pipe, it achieves accurate identification of obstructed pipe sections in the return oil pipe for negative pressure transmission. Based on this, using a preset liquid level height ratio as the optimization target, it performs pipe diameter optimization calculations on the obstructed pipe sections to determine the optimal pipe diameter that meets the optimization target, ensuring smooth negative pressure transmission. Simultaneously, it uses a CFD analysis model of the oil baffle to analyze the variation law of lubricating oil leakage rate under different bearing housing operating negative pressures and oil baffle installation clearances, thereby determining the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle. The method for optimizing the anti-leakage of the lubricating oil system in a steam turbine generator set provided by this invention incorporates return oil pipe diameter optimization, bearing housing negative pressure control, and oil baffle installation clearance into a unified framework, and generates an overall anti-leakage optimization scheme based on the optimal pipe diameter, optimal operating negative pressure, and optimal installation clearance, thereby fundamentally preventing lubricating oil leakage and improving the operational stability and reliability of the steam turbine generator set lubricating oil system. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0047] Figure 1 A flowchart of an optimization method for preventing leakage in the lubrication oil system of a steam turbine generator set, provided as an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of a three-dimensional solid model of a lubricating oil supply system provided in an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of a simulation model of a lubricating oil supply system provided in an embodiment of the present invention;

[0050] Figure 4 The simulation results curves of oil supply flow rate of each bearing under different oil supply pressures are provided for embodiments of the present invention.

[0051] Figure 5 This is a schematic diagram of the packaged oil pipe structure of the return oil pipe provided in an embodiment of the present invention;

[0052] Figure 6 This is a graph showing the percentage change in liquid level in the return branch pipe under different oil supply pressures, provided in an embodiment of the present invention.

[0053] Figure 7 This is a graph showing the percentage change in the liquid level in the return oil header under different oil supply pressures, provided in an embodiment of the present invention.

[0054] Figure 8 This is a schematic diagram of the fluid domain meshing of the oil baffle CFD analysis model provided in an embodiment of the present invention;

[0055] Figure 9 The leakage rate as a function of bearing housing negative pressure is provided for the embodiments of the present invention.

[0056] Figure 10 The leakage rate as a function of the oil baffle installation gap is provided for an embodiment of the present invention.

[0057] Figure 11 A schematic diagram of the structure of the anti-leakage optimization system for the lubricating oil system of a steam turbine generator set provided in an embodiment of the present invention. Detailed Implementation

[0058] The embodiments of the present invention will now be described with reference to the accompanying drawings. The terminology used in the embodiments section is for illustrative purposes only and is not intended to limit the scope of the invention.

[0059] The embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided by the embodiments of the present invention are equally applicable to similar technical problems.

[0060] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of the invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0061] There are three main reasons for leakage in the lubricating oil system of steam turbine generator sets: First, there are design flaws in the return oil pipeline, with some sections having too small a diameter. When the oil supply pressure increases, the liquid level in the pipe becomes too high, or even full, hindering the normal transmission of negative pressure and causing insufficient negative pressure in the bearing housing, thus failing to effectively suppress lubricating oil leakage. Second, the negative pressure control of the bearing housing is unreasonable, and the negative pressure value does not meet the requirements of the optimal sealing condition. Third, the oil baffle installation clearance is improperly set. If the clearance is too large, the leakage rate will increase sharply, and if the clearance is too small, it will easily cause dynamic and static friction between the rotor and the oil baffle.

[0062] Based on the above findings, this invention proposes an optimization method for preventing leakage in the lubricating oil system of a steam turbine generator set. This method can effectively solve the problem of oil leakage in the lubricating oil system. The following embodiments will introduce the optimization method for preventing leakage in the lubricating oil system of a steam turbine generator set provided by this invention.

[0063] Please see Figure 1 The diagram illustrates a flowchart of an optimization method for preventing leakage in a steam turbine generator set lubrication oil system, provided by an embodiment of the present invention. This method may include:

[0064] Step S101: Establish a simulation model of the lubricating oil supply system of the steam turbine generator set, and calculate the oil supply flow rate of each bearing under different oil supply pressures based on the simulation model.

[0065] A three-dimensional solid model of the lubricating oil supply system can be constructed based on the design drawings of the steam turbine generator set lubricating oil system. Then, a simulation model of the lubricating oil supply system can be constructed based on the geometric parameters of the three-dimensional solid model.

[0066] The simulation model of the lubricating oil supply system is used to simulate the flow behavior of lubricating oil in components such as the main supply pipe, branch pipe, orifice plate flow meter, oil cooler and filter. In this embodiment, the oil supply flow rate of each bearing under different oil supply pressures is calculated based on the simulation model.

[0067] Step S102: Based on the principle of mass conservation, using the calculated oil supply flow rate as input, establish a mathematical model of the flow state in the return oil pipe, and obtain the liquid level height ratio of each section of the return oil pipe under different oil supply pressures by solving the mathematical model of the flow state in the return oil pipe.

[0068] Based on the principle of mass conservation, the sum of the oil supply flow rates of each bearing calculated above is taken as the flow input of the return oil pipe, and minute leakage is ignored, so the return oil flow rate is considered to be equal to the supply oil flow rate.

[0069] The mathematical model of the flow state inside the return oil pipe is a set of nonlinear equations based on the principle of driving force-resistance balance, with the liquid level height as the unknown variable. It is used to describe the state of the two-phase stratified flow of oil and gas inside the return oil pipe. The driving force is the superposition of the component of fluid gravity along the pipe direction and the pressure gradient of the negative pressure fan, and the resistance is the frictional resistance along the pipe.

[0070] Step S103: Based on the obtained liquid level height ratio and combined with the on-site bearing box pressure measurement data, identify the return oil pipe section where negative pressure transmission is obstructed.

[0071] By combining the calculated percentage of liquid level in each section of the return oil pipe with the on-site measured bearing box pressure data (pressure inside the bearing box), the return oil pipe sections where negative pressure transmission is obstructed can be identified.

[0072] Step S104: Using the preset liquid level height ratio as the optimization target, perform pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, and obtain the optimal pipe diameter for the return oil pipe section where negative pressure transmission is obstructed.

[0073] After identifying the return oil pipe section where negative pressure transmission is obstructed, the pipe diameter is optimized for the identified section with a preset liquid level height ratio as the optimization target, thereby obtaining the optimal pipe diameter for the return oil pipe section where negative pressure transmission is obstructed.

[0074] Step S105: Establish a computational fluid dynamics (CFD) analysis model for the oil baffle. Based on the CFD analysis model, analyze the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances. Based on the lubricating oil leakage rate obtained from the analysis, determine the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle.

[0075] Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures (such as 0 kPa, -0.3 kPa, -0.5 kPa, -0.8 kPa, -1.0 kPa) and different oil baffle installation clearances (such as 0.30 mm, 0.50 mm, 0.6075 mm, 0.80 mm, 1.00 mm) is simulated to obtain the leakage rate variation law. Then, based on the leakage rate variation law, the optimal operating negative pressure of the bearing housing and the optimal installation clearance range of the oil baffle are determined.

[0076] Step S106: Based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, generate an overall optimized solution for preventing leakage of the lubricating oil system.

[0077] After obtaining the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, an overall optimization scheme for preventing leakage of the lubricating oil system is generated based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle. After obtaining the overall optimization scheme for preventing leakage, the lubricating oil system can be optimized for preventing leakage based on the optimization scheme.

[0078] The overall optimization plan for preventing leakage in the lubricating oil system may include: replacing or modifying the return oil pipe section where negative pressure transmission is obstructed according to the optimized pipe diameter; adjusting the operating negative pressure of the bearing box to the optimal operating negative pressure (such as -0.5kPa); and controlling the oil baffle installation clearance within the optimal installation clearance range (such as 0.30mm~0.60mm).

[0079] By optimizing the return oil pipe diameter, controlling the bearing housing negative pressure, and adjusting the oil baffle installation clearance in a coordinated manner, the potential for lubricating oil leakage was fundamentally eliminated, and the operational stability and reliability of the turbine generator set's lubricating oil system were improved.

[0080] The leak-proof optimization method for the lubricating oil system of a steam turbine generator set provided in this invention achieves accurate identification of the obstructed pipe section for negative pressure transmission in the return oil pipe through the linkage analysis of the oil supply system simulation model and the mathematical model of the flow state in the return oil pipe. Based on this, with a preset liquid level height ratio as the optimization target, the pipe diameter of the obstructed pipe section for negative pressure transmission is optimized to determine the optimal pipe diameter that meets the optimization target, thereby ensuring smooth negative pressure transmission. Simultaneously, the CFD analysis model of the oil baffle is used to analyze the variation law of lubricating oil leakage rate under different bearing housing operating negative pressures and oil baffle installation clearances, thereby determining the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle. The leak-proof optimization method for the lubricating oil system of a steam turbine generator set provided in this invention incorporates return oil pipe diameter optimization, bearing housing negative pressure control, and oil baffle installation clearance into a unified framework, and generates an overall leak-proof optimization scheme based on the optimal pipe diameter, optimal operating negative pressure, and optimal installation clearance, thereby fundamentally preventing lubricating oil leakage and improving the operational stability and reliability of the steam turbine generator set lubricating oil system.

[0081] In some embodiments of this application, the specific process of "establishing a simulation model of the lubricating oil supply system of the steam turbine generator set" in the above embodiments is described.

[0082] In one possible implementation, the process of establishing a simulation model of the lubricating oil supply system for a steam turbine generator set may include:

[0083] Step a1: Based on the design drawings of the steam turbine generator set lubrication oil system, construct a three-dimensional solid model of the lubrication oil supply system.

[0084] Among them, the three-dimensional solid model can be a three-dimensional CAD model based on the isometric drawing (ISO drawing) of the pipeline of the steam turbine generator set lubricating oil system. The three-dimensional solid model can intuitively reflect the structural topology and key geometric parameters of the lubricating oil supply system.

[0085] When constructing a 3D solid model of a lubricating oil supply system, geometric information is extracted from the design drawings, and then the 3D solid model is constructed based on this extracted geometric information. Please refer to [link / reference]. Figure 2 This example demonstrates a three-dimensional solid model of a lubricating oil supply system. The three-dimensional solid model can accurately reproduce the actual geometric positions and connections of components such as pipeline routing, spatial layout, pipe diameter variations, elevations, elbows, tees, valves, and bearings.

[0086] Step a2: Based on the geometric parameters of the three-dimensional solid model, construct a preliminary simulation model of the lubricating oil supply system.

[0087] After completing the construction of the three-dimensional solid model of the lubricating oil supply system, a preliminary simulation model of the lubricating oil supply system can be constructed based on the geometric parameters of the three-dimensional solid model. For example, a preliminary simulation model of the lubricating oil supply system can be built in Flowmaster.

[0088] The preliminary simulation model is a numerical calculation model built based on the geometric parameters (such as pipe length, pipe diameter, elevation, slope, and pipe type) of the three-dimensional solid model. Please refer to [link / reference]. Figure 3 It shows an example of a simulation model of a lubricating oil supply system. The simulation model of the lubricating oil supply system is a fluid network structure formed by abstracting a three-dimensional solid model. In this fluid network, components such as the main supply pipe, branch pipes, orifice flow meters, oil coolers, and filters are all defined as calculation units with specific flow resistance characteristics.

[0089] In the process of building the preliminary simulation model, the pipe length, pipe diameter and slope data obtained from the three-dimensional solid model are input into fluid simulation software such as Flowmaster, and the fluid medium is defined as No. 46 turbine oil (VG46). According to its temperature fitting equation, physical property parameters such as density and dynamic viscosity are input. Through this conversion from geometric entity to numerical network, the preliminary simulation model has the ability to calculate flow distribution, flow velocity and pressure drop under different oil supply pressures. However, the calculation accuracy under the initial state still needs to be verified by measured data.

[0090] Step a3: Validate the preliminary simulation model using the on-site measured oil supply flow data of each bearing.

[0091] Verifying the preliminary simulation model using on-site measured oil supply flow data for each bearing involves comparing the oil supply flow data calculated by the simulation model with the on-site measured oil supply flow data to evaluate the accuracy of the simulation model.

[0092] Specifically, verifying the preliminary simulation model using on-site measured oil supply flow data for each bearing can include:

[0093] Step a31: Calculate the oil supply flow rate of each bearing under different oil supply pressures based on the preliminary simulation model, and obtain the simulated oil supply flow rate of each bearing under different oil supply pressures.

[0094] Specifically, different oil supply pressure values ​​(e.g., pressure points covering the normal operating range of the unit, such as 180 kPa, 200 kPa, and 220 kPa) are sequentially input as boundary conditions into the preliminary simulation model. The model internally performs numerical solutions based on the fluid dynamics continuity equation and momentum equation, automatically calculating the theoretical oil supply flow rate of each bearing in the turbine generator unit at each input pressure point. This generates a set of simulated oil supply flow rate datasets containing the mapping relationship between oil supply pressure, bearing number, and simulated flow rate. By traversing multiple pressure points, the model's response characteristics throughout the entire operating range can be comprehensively evaluated, thus providing sufficient data samples for subsequent deviation comparisons.

[0095] Step a32: Compare the simulated oil supply flow rate of each bearing under different oil supply pressures with the corresponding measured oil supply flow rate.

[0096] Specifically, measured oil flow rate data that is completely consistent with the simulation conditions described above is obtained to ensure that the comparison is conducted under the same oil supply pressure and the same bearing position. The comparison process adopts a point-to-point correspondence method, that is, the simulated flow rate value of a certain bearing at a specific pressure is compared with the measured flow rate value of the same bearing at the same pressure using difference calculation or ratio calculation. For example, when the oil supply pressure is 201.5 kPa, the simulated oil supply flow rate of bearing #3 at this oil supply pressure (45.2 m³ / h) is compared with the measured oil supply flow rate of bearing #3 at this oil supply pressure. Through intensive comparison of all operating conditions and all bearings, it is possible to identify which pressure ranges or pipeline branches in the model have systematic deviations.

[0097] Step a33: If all comparison deviations are within the allowable range of the project, the preliminary simulation model is deemed to have passed the verification; otherwise, the preliminary simulation model is deemed to have failed the verification.

[0098] This step determines the model's validity based on pre-defined quantitative criteria. The engineering allowable range can be the maximum permissible error interval determined according to the operation and maintenance standards of the lubrication oil system of nuclear power or thermal power turbine generator sets. For example, the engineering allowable range can be set to a relative deviation between the simulated value and the measured value not exceeding ±7%. The judgment logic requires that all comparison deviations be within this range, meaning it's a veto mechanism: if the flow deviation of any bearing at any test pressure point exceeds this threshold (e.g., a deviation of 10% at a certain point), the entire preliminary simulation model is deemed unverified, indicating uncorrected structural parameter errors or improper boundary condition settings in the model, requiring correction. Conversely, only when the deviation curves of all sampling points converge within the engineering allowable range is the model deemed valid. At this point, the model is confirmed as the final simulation model and can be used for subsequent return oil flow state analysis and optimization calculations. This rigorous full-domain verification mechanism effectively avoids the risk of overall model distortion being masked by coincidental local data matches, ensuring that subsequent pipe diameter optimization schemes and negative pressure control strategies derived from this model have a solid physical basis.

[0099] This invention achieves standardization and objectification of the simulation model verification process through the synergistic effect of the above steps. By transforming the abstract evaluation of model accuracy into a concrete calculation-comparison-judgment data flow, the subjective arbitrariness of human experience-based judgment is eliminated. The generated full-condition simulation data provides breadth for verification, the precise comparisons provide depth, and the dual constraints based on the deviations of each comparison and the allowable range in engineering provide stringent entry standards. The combination of these three elements ensures that the simulation model entering the subsequent optimization stage has high confidence.

[0100] For example, measured oil supply flow data at supply pressures of 180.7 kPa, 201.5 kPa, and 255.4 kPa are selected, and simulated oil supply flow data at 180.7 kPa, 201.5 kPa, and 255.4 kPa are obtained based on the preliminary simulation model. If the deviation between the simulated oil supply flow data and the corresponding measured oil supply flow data for each bearing is controlled within the allowable engineering range (e.g., maximum deviation ≤ 7%), the model is deemed reliable. This verification mechanism utilizes field measured data as the gold standard, effectively identifying model distortion caused by excessive simplification of geometric parameters or improper setting of physical property parameters, ensuring that the simulation results can truly reflect the unit's oil supply characteristics.

[0101] Step a4-a: If the verification is successful, the preliminary simulation model will be determined as the final simulation model.

[0102] Step a4-b: If the verification fails, the preliminary simulation model is modified, and the modified simulation model is re-verified using the on-site measured oil supply flow data of each bearing. If the verification passes, the modified simulation model is determined as the final simulation model.

[0103] If the revised simulation model fails verification, the revised simulation model will continue to be revised and verified until it passes verification.

[0104] The correction process refers to adjusting the geometric parameters, local resistance coefficients, or boundary conditions of pipe sections or components that failed verification, forming a closed-loop iterative mechanism of modeling-verification-correction. Specifically, when the deviation between simulated and measured flow rates exceeds the allowable range for engineering, the pipe section with the largest deviation is located, and the cause is analyzed to determine whether it stems from inaccurate estimation of the pipe's inner wall roughness, missing resistance coefficients of local pipe fittings, or geometrical dimensional errors in the 3D model. Based on this, the initial simulation model is corrected accordingly. For example, if the simulated flow rate of a bearing branch is 15% higher than the measured value, it is necessary to check whether the pipe diameter input in the 3D solid model of that branch is too large, or whether the resistance of certain throttling elements has been ignored in the simulation model. After correction, the actual measured data is substituted back into the model for verification. Through this iterative correction until the flow deviation of all key nodes meets the accuracy requirements, the final simulation model not only possesses the rigor of theoretical calculations but also the credibility for engineering applications. This provides accurate oil supply flow input for the subsequent establishment of a mathematical model of the flow state in the return oil pipe, ensuring the reliability of the data source for the entire leak prevention optimization scheme.

[0105] This invention achieves high-precision reconstruction of a digital twin of an oil supply system through the coordinated construction of a 3D solid model and a simulation model, along with a verification and correction mechanism driven by measured data. The 3D solid model provides a realistic geometric and topological foundation, avoiding parameter omissions; measured data verification ensures the engineering credibility of the simulation results; and the dynamic correction mechanism eliminates the deviation between the theoretical model and actual operating conditions. The synergistic effect of these three elements enables the final simulation model to accurately map the system response under different oil supply pressures, fundamentally solving the technical problem of unreliable input for return oil analysis due to model distortion. This lays a solid data foundation for subsequent identification of obstructed negative pressure transmission pipe sections and the development of leak prevention optimization schemes.

[0106] After obtaining the final simulation model, the oil supply flow rate of each bearing under different oil supply pressures can be calculated based on the simulation model. Please refer to [link / reference]. Figure 4 The simulation results of the oil supply flow rate of each bearing under different oil supply pressures are shown in the figure. The figure shows the nonlinear growth trend of the oil supply flow rate of each bearing as the oil supply pressure changes from 100 kPa to 300 kPa. This data will serve as an accurate input source for the subsequent flow state analysis in the return oil pipe.

[0107] After calculating the oil supply flow rate of each bearing under different oil supply pressures based on the simulation model, a mathematical model of the flow state in the return oil pipe is established based on the principle of mass conservation, using the calculated oil supply flow rate as input. In some embodiments of this application, the process of establishing a mathematical model of the flow state in the return oil pipe based on the principle of mass conservation, using the calculated oil supply flow rate as input, is introduced.

[0108] In one possible implementation, the process of establishing a mathematical model of the flow state within the return oil pipe, based on the principle of mass conservation and using the calculated oil supply flow rate as input, may include:

[0109] Step b1: Using the oil supply flow rate of each bearing under different oil supply pressures as the return oil flow rate input, analyze the driving force and resistance of the return oil pipe flow.

[0110] The oil supply flow data of each bearing calculated by the above simulation model are directly mapped to the initial flow boundary conditions in the return oil pipe based on the principle of mass conservation (assuming that the return oil flow is equal to the supply oil flow while ignoring minor leakage).

[0111] The driving force is the power source that propels the lubricating oil to flow in the return oil pipe. It consists of two parts: first, the component of gravity along the pipe direction, which depends on the pipe's slope and the oil density, reflecting gravity's contribution to fluid movement; and second, the pressure gradient generated by the negative pressure fan at the top of the oil tank, transmitted to the gas phase space of the return oil pipe through the return gas pipe, creating a suction effect. These two factors combined constitute the total driving force for the return oil flow. Resistance refers to the frictional resistance along the flow path that impedes fluid flow. Its magnitude is related to the pipe wall roughness, fluid velocity, and hydraulic radius. Analyzing the driving force and resistance is a prerequisite for establishing the equilibrium equation, as both together determine the steady-state liquid level in the return oil pipe. For example, in a megawatt-class nuclear power turbine generator unit, when the oil supply pressure increases from 180 kPa to 230 kPa, the return oil flow rate increases. If the pressure gradient provided by the negative pressure fan is insufficient to overcome the rapidly increasing frictional resistance due to the increased flow velocity, the liquid level will rise. By quantitatively analyzing the superposition effect of the gravitational component and the negative pressure gradient, the actual magnitude of the driving force under different working conditions can be accurately assessed, providing accurate mechanical input for subsequent calculations.

[0112] Step b2: Based on the geometric characteristics of the packaged oil pipe structure of the return oil pipe, calculate the cross-sectional area and wetted perimeter of the return oil pipe in segments, and establish the balance equation of driving force and resistance based on the calculated cross-sectional area and wetted perimeter.

[0113] The return oil pipe's nested oil pipe structure is a composite pipe structure consisting of a return oil pipe and a jacking oil pipe nested inside. Please refer to [link / reference needed]. Figure 5 It shows the packaged tubing structure of the return oil pipe. Figure 5The relative positions of the return oil pipe, lubricating oil pipe and jacking oil pipe are clearly shown. The multi-layer nested structure of the tubing results in the cross-section of the return oil channel not being a standard circle, but exhibiting a complex irregular geometric shape as the liquid level changes. The design of the tubing is intended to arrange the pipelines compactly, but when performing fluid dynamics calculations, the impact of the internal pipes on the fluid flow area and contact perimeter must be accurately considered.

[0114] Due to the presence of internal nested pipes (lubricating oil pipe and jacking oil pipe), the rate of change of cross-sectional area and wetted perimeter will change abruptly as the liquid level rises, so segmented calculation is required.

[0115] Specifically, based on the relationship between the liquid level and the position of the internal pipes, the calculation process is divided into several operating conditions, including: the liquid level not contacting the jacking pipe, contacting the jacking pipe but not completely submerged, the jacking pipe being completely submerged but not contacting the lubricating pipe, contacting the lubricating pipe but not completely submerged, and the lubricating pipe being completely submerged. Then, the cross-sectional area and wetted perimeter of the return pipe are calculated for each of these conditions. The cross-sectional area of ​​the return pipe refers to the actual flow cross-sectional area occupied by the lubricating oil at the current liquid level, excluding the space occupied by the internal nested pipes. The wetted perimeter of the return pipe refers to the total perimeter of the area directly in contact with the pipe walls (including the inner wall of the return pipe, the outer wall of the lubricating pipe, and the outer wall of the jacking pipe) at that liquid level.

[0116] "Liquid surface not in contact with the jacking pipe" means the liquid level is lower than the bottom of the jacking pipe, and the return oil flow section is the arc-shaped area enclosed by the inner wall of the return oil pipe and the liquid surface; the internal pipes are not included in the section calculation. "Contact with the jacking pipe but not completely submerged" means the liquid level is between the bottom and top of the jacking pipe, and the flow section needs to deduct the cross-sectional area of ​​the jacking pipe below the liquid level. "Jacking pipe completely submerged but not in contact with the lubricating oil pipe" means the liquid level is higher than the top of the jacking pipe but lower than the bottom of the lubricating oil pipe; in this case, the entire cross-section of the jacking pipe is deducted, and the flow section is the arc-shaped area of ​​the return oil pipe minus the area of ​​the complete jacking pipe circle. "Contact with the lubricating oil pipe but not completely submerged" means the liquid level is between the bottom and top of the lubricating oil pipe, and the flow section needs to deduct both the area of ​​the complete jacking pipe circle and the cross-sectional area of ​​the lubricating oil pipe below the liquid level. "Lubricating oil pipe completely submerged" means the liquid level is higher than the top of the lubricating oil pipe; in this case, both internal pipes are completely submerged, and the flow section is the arc-shaped area of ​​the return oil pipe minus the areas of two complete internal circles.

[0117] By dividing the working conditions into detailed steps, it can be ensured that the cross-sectional area calculation conforms to the actual physical boundary at any liquid level, thus avoiding the systematic deviation caused by simplifying the tubing to a single equivalent diameter in traditional methods.

[0118] During the calculation, for each operating condition, the region where the liquid surface is located is first determined, and then the corresponding geometric algorithm is called: for the condition where the inner tube is not in contact or is only partially in contact, the area of ​​the inner tube cut by the liquid surface is calculated using the circular arc area formula combined with trigonometric functions; for the condition where the inner tube is completely submerged, the area of ​​the entire circle of the inner tube is directly subtracted. The calculation of the wetted perimeter follows the same logic, accumulating the arc lengths of all solid boundaries below the liquid surface. For example, in the condition where the contact top shaft tubing is not completely submerged, the cross-sectional area is equal to the arc area of ​​the return tubing below the liquid surface minus the arc area of ​​the top shaft tubing below the liquid surface, and the wetted perimeter is equal to the arc length of the return tubing below the liquid surface plus the arc length of the top shaft tubing below the liquid surface.

[0119] This embodiment achieves accurate modeling of return oil flow parameters under complex nested tubing structures. By clearly defining the nested structure of the tubing and combining it with five specific operating conditions defined by the relationship between liquid level and inner tube position, the calculation of cross-sectional area and wetted perimeter can dynamically adapt to geometric changes caused by liquid level variations. This refined geometric processing method, closely integrated with the flow state mathematical model based on the principle of mass conservation, effectively solves the problem of calculation distortion in traditional simplified models when dealing with multi-tube nested structures.

[0120] After calculating the cross-sectional area and wetted perimeter for each operating condition, the hydraulic radius (the ratio of cross-sectional area to wetted perimeter) for each condition can be further determined. The hydraulic radius is a key parameter for calculating frictional resistance along the pipe, directly affecting the value of the resistance term. Based on the calculated cross-sectional area, wetted perimeter, and the derived parameters such as flow velocity and friction coefficient, a balance equation for driving force and resistance is established. This equation is essentially a nonlinear system of equations with liquid level as an unknown variable, expressing the steady-state flow condition that gravity component + negative pressure gradient = frictional resistance along the pipe. For example, when the liquid level is in a condition where the contact top shaft tubing is not completely submerged, a small rise in liquid level will lead to a significant increase in wetted perimeter (because it is simultaneously in contact with the inner wall of the outer tube and the outer wall of the inner tube), resulting in a decrease in hydraulic radius and an increase in frictional resistance. This nonlinear characteristic must be reflected in the balance equation through a piecewise function to ensure that the model can accurately reflect the flow resistance characteristics within the tubing.

[0121] Step b3: Perform numerical iteration to solve the equilibrium equation to obtain the percentage of liquid level in each section of the return oil pipe under different oil supply pressures.

[0122] Since the frictional resistance coefficient, average flow velocity of the cross section, and hydraulic radius in the established equation for the balance of driving force and resistance are all nonlinear functions of the liquid level height, the equation cannot be solved directly by analytical methods. Therefore, a numerical iterative method is used to solve it.

[0123] Numerical iterative solution involves setting an initial guessed liquid level (usually chosen based on engineering experience, such as 50% of the pipe diameter), substituting it into the equilibrium equation to calculate the residual (the difference between the driving force and the resistance). Then, based on the magnitude and direction of the residual, optimization algorithms such as the Newton-Raphson method are used to adjust the liquid level value, and the calculation is repeated until the residual is less than the preset allowable error. The liquid level obtained at this point is the convergent solution of the equation. The liquid level height ratio refers to the ratio of the calculated steady-state liquid level height to the inner diameter of the return oil pipe. This parameter is a core indicator for judging whether the return oil is unobstructed and whether the negative pressure transmission is blocked. Through numerical iteration, the difficulty of solving nonlinear equations can be overcome, ensuring the feasibility and accuracy of engineering calculations. For example, when calculating the B4 section of the return oil header of a nuclear power unit, with the supply pressure set at 201.5 kPa, iterative solutions revealed that when the liquid level reaches 97.6%, the driving force and resistance reach equilibrium. At this point, the pipe is almost full, and the gas phase passage is extremely compressed, indicating a serious risk of negative pressure transmission obstruction in this section. This method can automatically output corresponding liquid level percentage curves for different supply pressures (e.g., the range of 100 kPa to 300 kPa), providing a quantitative basis for identifying obstructed pipe sections and optimizing pipe diameter.

[0124] Please see Figure 6 and Figure 7 , Figure 6 This is a graph showing the change in the percentage of liquid level in the return branch pipe under different oil supply pressures. Figure 7 This is a graph showing the change in the percentage of liquid level in the return oil header under different oil supply pressures. Figure 6 and Figure 7 The paper details the changes in the liquid level ratio of the return branch pipe (e.g., A1-A7) and the return main pipe (e.g., B1-B7) as the pressure increases under different oil supply pressure conditions. Some pipe sections have a liquid level ratio close to 100% under high pressure, indicating a full pipe state.

[0125] By establishing and solving mathematical models, the causes of poor oil return can be upgraded from empirical judgment to quantitative diagnosis, accurately calculating the liquid level filling degree of each pipe section, and providing direct criteria for identifying pipe sections where negative pressure transmission is obstructed.

[0126] This invention achieves a precise mapping between the supply oil flow rate and the return oil level by constructing a mathematical model of the return oil pipe flow state that incorporates dual driving force coupling and segmented geometric characteristics. Specifically, by superimposing the component of fluid gravity along the pipe direction with the pressure gradient of the negative pressure fan as the driving force, the power source of the nuclear power turbine return oil system is accurately reproduced, avoiding underestimation of the liquid level due to neglecting the negative pressure effect. By combining the geometric characteristics of the packaged oil pipe to calculate the cross-sectional area and wetted perimeter segmentally, the nonlinear influence of inner pipe interference on the hydraulic radius and frictional resistance is accurately captured, significantly reducing the calculation error of the liquid level percentage. Through numerical iteration to solve the equilibrium equations, the problem of solving complex nonlinear equation sets is solved, ensuring that the liquid level percentage of each pipe segment can be obtained quickly and accurately under different supply oil pressures.

[0127] After obtaining the percentage of liquid level in each section of the return oil pipe under different oil supply pressures, the return oil pipe section where negative pressure transmission is obstructed can be identified based on the obtained percentage of liquid level and the actual measured pressure data of the bearing box on site. This process is described in some embodiments of the present invention.

[0128] In one possible implementation, the process of identifying return oil pipe sections with obstructed negative pressure transmission, based on the percentage of liquid level in each section of the return oil pipe under different supply pressures, and in conjunction with on-site bearing box pressure measurement data, may include:

[0129] Step c1: Obtain the percentage of liquid level in each return oil pipe section within the target oil supply pressure range.

[0130] The target oil supply pressure range can refer to the oil supply pressure range specified during normal operation or in the design of the steam turbine generator set. For example, the target oil supply pressure range can be set to 170 kPa to 230 kPa. The liquid level height ratio refers to the ratio of the lubricating oil level height in the return oil pipe to the inner diameter of the pipe. This parameter directly reflects the size and flow capacity of the gas passage in the return oil pipe.

[0131] Step c2: Identify the pipe section where the liquid level height ratio exceeds the preset liquid level height ratio threshold and the corresponding bearing box measured pressure is higher than the preset negative pressure benchmark or the corresponding bearing box measured pressure is in a slightly positive pressure state as the return oil pipe section where negative pressure transmission is blocked.

[0132] The preset liquid level height percentage threshold is a critical indicator for judging whether the return oil pipe is close to full flow. It is usually set based on engineering experience and the need to retain gas channels, for example, it can be set to 85%. When the liquid level height percentage exceeds this threshold, it indicates that the gas flow cross section in the return oil pipe is drastically reduced, which can easily form gas resistance, causing the upstream negative pressure to be unable to be effectively transmitted.

[0133] The preset negative pressure reference is the oil tank design negative pressure (the target negative pressure value designed inside the oil tank, such as -0.5kPa), and the slightly positive pressure state can refer to the state where the pressure inside the bearing housing is higher than atmospheric pressure (standard atmospheric pressure 100.6kPa).

[0134] This invention employs a dual verification logic combining mechanistic criteria and on-site phenomenon criteria to identify obstructed pipe sections: First, pipe sections with a liquid level exceeding 85% are screened. These sections have a significantly reduced gas flow cross-section, which hinders negative pressure transmission. Then, based on the corresponding bearing box negative pressure measurement data, a second judgment is made. Pipe sections with bearing box measured pressure higher than a preset negative pressure benchmark (e.g., -0.5 kPa) or with corresponding bearing box measured pressure in a slightly positive state are identified as pipe sections with obstructed negative pressure transmission.

[0135] The dual-threshold joint judgment method not only utilizes the predictive power of simulation calculations but also introduces the correction effect of field measured data, realizing a leap from qualitative analysis to quantitative decision-making, significantly improving the accuracy of diagnosis, and ensuring the targeting of subsequent pipe diameter optimization calculations.

[0136] This invention establishes a robust mechanism for identifying negative pressure transmission obstruction by acquiring the percentage of liquid level within the target oil supply pressure range and performing dual verification using on-site measured bearing housing pressure data. By setting a specific liquid level percentage threshold (e.g., 85%), it accurately captures the critical state where the return oil pipe is about to fill and the gas channel is about to disappear. Simultaneously, by comparing the measured negative pressure data with a preset benchmark or slightly positive pressure state, it eliminates false positive results that might arise from relying solely on model calculations.

[0137] After identifying the return oil pipe section where negative pressure transmission is obstructed, the pipe diameter of the obstructed return oil pipe section is optimized by using a preset liquid level height ratio as the optimization target, and the optimal pipe diameter of the obstructed return oil pipe section is obtained. This process is described in some embodiments of the present invention.

[0138] In one possible implementation, the process of optimizing the pipe diameter of the return oil pipe section where negative pressure transmission is obstructed, using a preset liquid level height percentage as the optimization objective, can include:

[0139] Step d1: From the pipe sections where negative pressure transmission is obstructed, determine the pipe sections to be optimized according to the preset pipe section selection rules.

[0140] Among them, the preset pipe segment selection rules are a set of logical criteria used to select priority targets for modification from all obstructed pipe segments, aiming to focus optimization resources on the bottleneck links that have the greatest impact on system performance.

[0141] Specifically, the preset pipe segment selection rules may include: for return branch pipes, selecting the inlet pipe segment; for return main pipes, selecting pipe segments in order of priority from small to large pipe diameter (e.g., selecting pipe segments with smaller pipe diameter); and selecting pipe segments in order of priority from large to small oil supply flow, from small to large pipe slope, and from high to low liquid level height percentage (e.g., selecting pipe segments with large oil supply flow, small pipe slope, and high liquid level height percentage).

[0142] This invention achieves the synergistic application of differentiated strategies for return branch pipes and main pipes through the aforementioned pipe segment selection rules. For return branch pipes, the selection rules for inlet pipe segments address the critical point of negative pressure transmission in the branch pipe system, resolving the issue of negative pressure failure in the entire branch pipe due to liquid seals at the initial end. For return main pipes, the selection rules based on pipe diameter directly pinpoint the physical bottleneck in flow, ensuring targeted expansion and modification. Furthermore, a triple comprehensive optimization mechanism based on the ratio of oil supply flow rate, pipe slope, and liquid level height is introduced, combining fluid load, geometry, and real-time flow status to form a tight logical closed loop. This multi-dimensional selection strategy not only avoids material waste and spatial conflicts caused by blindly expanding pipe diameter but also ensures that the optimized pipe diameter fundamentally eliminates excessively high liquid levels caused by excessive flow, too gentle slope, or too small pipe diameter. This ensures that the negative pressure generated by the negative pressure fan can be smoothly transmitted to each bearing housing, forming a perfect system match with the aforementioned optimal operating negative pressure and optimal oil baffle installation clearance, jointly achieving the overall optimization goal of leak prevention in the lubricating oil system.

[0143] Step d2: Using the preset multi-level liquid level height ratio as the optimization target, perform pipe diameter optimization calculations on the pipe section to be optimized to obtain the optimal pipe diameter that meets the optimization target.

[0144] The optimization objective of multi-level liquid level height ratio can refer to setting two or more liquid level filling rate thresholds for the flow state of the return oil pipe section as constraints for pipe diameter inversion calculation.

[0145] For example, using multi-level liquid level percentages as optimization targets can include benchmark targets based on industry standards and flexible targets based on engineering economics and feasibility of modifications. Benchmark targets are typically set according to the provisions on semi-pipe flow in the "Design Code for Oil and Gas Pipelines in Power Plants," such as setting the liquid level percentage at 50% to ensure that the return oil pipeline theoretically meets the requirements for non-full-pipe flow and guarantees the maximum cross-sectional area of ​​the gas passage. Flexible targets are set based on actual site space constraints, cost control, and operational margins; for example, setting the liquid level percentage at 75%, while higher than the standard benchmark, still maintains an effective negative pressure transmission channel in engineering practice, while avoiding material waste and installation difficulties caused by excessive pipe diameter enlargement. This tiered strategy allows for differentiated solutions to obstructed pipe sections of varying severity, meeting compliance requirements while retaining flexibility in engineering implementation.

[0146] Pipe diameter optimization calculation involves calculating the pipe diameter backwards from a preset optimization target to obtain the optimal pipe diameter that meets the optimization target. For example, with a target of 50% liquid level coverage, all pipe sections to be optimized need to have their diameter increased. With a target of 75% liquid level coverage, the optimal pipe diameter for section A4 is 354 mm (original diameter 323.8 mm), for section B3 it is 420.3 mm (original diameter 406.4 mm), for section B4 it is 480.2 mm (original diameter 406.4 mm), for section B5 it is 569 mm (original diameter 508.0 mm), for section B6 it is 632.4 mm (original diameter 610.0 mm), and for section B7 it is 644.4 mm (original diameter 610.0 mm).

[0147] This invention achieves refined and intelligent pipe diameter optimization by coordinating multi-level liquid level height ratio optimization objectives with preset pipe segment selection rules. The multi-level objectives prevent the optimization scheme from being rigid and singular, instead providing multiple options based on different needs for compliance with regulations and engineering economics. 50% of the objectives ensure absolute safety of the design scheme at the legal and regulatory level, while 75% provides a more practical technical path for the retrofitting of older units. The pipe segment selection rules further ensure that computational resources and retrofitting funds are concentrated on the bottleneck pipe segments that most severely hinder the transmission of negative pressure in the system. Based on this, pipe diameter inversion calculations based on multi-level objectives can transform abstract flow state requirements into specific physical dimensional parameters, thereby generating optimal pipe diameter data that conforms to fluid mechanics principles while also considering on-site implementation conditions.

[0148] In addition to identifying the return oil pipe section where negative pressure transmission is obstructed and determining the optimal pipe diameter for the return oil pipe section where negative pressure transmission is obstructed, this invention also establishes a CFD analysis model for the oil baffle. Based on the CFD analysis model, it analyzes the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances. Then, based on the lubricating oil leakage rate obtained from the analysis, it determines the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle.

[0149] The establishment of the CFD analysis model for the oil baffle refers to modeling the external oil baffle structure of the steam turbine generator set using the VOF (Volume of Fluid) two-phase flow method. Considering the circumferential symmetry of the oil baffle, the model can be simplified to a 1 / 4 structure with periodic boundary conditions. Local mesh refinement is performed on key areas such as sealing teeth and gaps, with a total mesh count reaching 2.8 million. The time step is controlled within the range of 0.1 to 0.5 Coulomb numbers to ensure convergence. The analysis of lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances based on CFD analysis model was achieved by setting multiple sets of working conditions for steady-state simulation and transient simulation. The specific working conditions include: setting different gradients of bearing housing negative pressure such as 0 kPa, -0.3 kPa, -0.5 kPa, -0.8 kPa, and -1.0 kPa, and different values ​​of oil baffle installation clearance such as 0.30 mm, 0.50 mm, 0.60 mm, 0.80 mm, and 1.00 mm, tracking the interface movement between lubricating oil and air, and calculating the lubricating oil leakage rate under each working condition.

[0150] Please see Figure 8 , Figure 8 This diagram illustrates the fluid domain meshing of the oil baffle CFD analysis model, showcasing the overall mesh distribution, locally refined regions, and boundary layer meshing details in the cross-sectional view, ensuring the accuracy of the simulation calculations. Please refer to... Figure 9 and Figure 10 , Figure 9 This is a graph showing the leakage rate as a function of the negative pressure in the bearing housing. Figure 10 The graph shows the leakage rate as a function of the oil baffle installation clearance. Figure 9 It can be seen that as the absolute value of negative pressure increases, the leakage rate gradually decreases, but the rate of decrease slows down after reaching a certain value. Figure 10 It can be seen that when the gap exceeds 0.60 mm, the leakage rate increases rapidly and non-linearly. Based on the above analysis results, the optimal operating negative pressure of the bearing housing is determined to be -0.5 kPa (at which the leakage rate can be controlled at around 1.5%), and the optimal installation gap range of the oil baffle is 0.30 mm to 0.60 mm (within this range, the leakage rate is low and dynamic and static contact between the rotor and the oil baffle can be avoided). Through CFD simulation and quantitative analysis, data-driven decision-making of the oil baffle sealing parameters is realized, balancing sealing performance and operational safety.

[0151] The optimal operating negative pressure of the bearing housing refers to the optimal pressure value determined under normal operating conditions of the steam turbine generator set to suppress lubricating oil leakage from the oil baffle outside the bearing housing, while avoiding excessive negative pressure that could increase turbine energy consumption or cause housing vibration. This value is a quantitative conclusion derived from a CFD analysis model, simulating the variation of lubricating oil leakage rate under different negative pressure conditions. Figure 9 As shown, when the bearing housing's operating negative pressure is set to -0.5 kPa, the lubricating oil leakage rate can be stably controlled at around 1.5%. At this point, the suction effect generated by the negative pressure is sufficient to overcome the leakage tendency caused by oil film surface tension and airflow disturbance, achieving the best balance between sealing performance and operating economy. If the negative pressure value is higher than this setting (e.g., close to 0 kPa or slightly positive pressure), the lubricating oil overflow path cannot be effectively blocked, leading to a significant increase in oil leakage. If the negative pressure value is much lower than this setting (e.g., -0.8 kPa), although the leakage rate may be further reduced, the load on the negative pressure fan will increase significantly, and the excessive pressure difference may exacerbate the stress risk on the bearing housing structure, or even affect the oil quality due to excessive air intake. Therefore, -0.5 kPa, as the optimal operating point verified by systematic simulation, directly guides the adjustment and control of the negative pressure fan on site, ensuring that a constant slightly negative pressure environment is maintained inside the bearing housing.

[0152] The optimal installation clearance range for the oil baffle refers to the radial distance interval reserved between the turbine rotor and the tip of the stationary oil baffle tooth. This interval is determined by comprehensively considering the lubricating oil leakage control effect and the mechanical safety of rotor operation. Figure 10 As shown, within a gap range of 0.30mm to 0.60mm, the lubricating oil leakage rate can be maintained below 1.5%, meeting the leakage prevention requirements. When the installation gap is at the lower limit of this range (e.g., 0.30mm), the throttling effect is significant, effectively limiting oil flow. However, strict control of installation accuracy is required to prevent rubbing between moving and stationary parts. When the installation gap is at the upper limit of this range (e.g., 0.60mm), sufficient flow resistance is still provided to maintain the leakage rate at a low level. At the same time, sufficient safety margin is provided for rotor displacement under thermal expansion, vibration, or eccentric conditions, completely avoiding the risk of dynamic and static rubbing between the rotor and the oil baffle. If the installation gap exceeds 0.60mm, simulation data shows that the leakage rate will show a non-linear and rapid upward trend, and the risk of seal failure will increase sharply. If the installation gap is too small (less than 0.30mm), friction failure is very likely to occur during unit start-up, shutdown, or changes in operating conditions. Therefore, strictly limiting the oil baffle installation gap to the range of 0.30mm to 0.60mm is the optimal solution for leakage prevention under the premise of ensuring zero rubbing.

[0153] This invention achieves precise coordination between gas-phase negative pressure control and solid-phase structural clearance by locking the optimal operating negative pressure of the bearing housing at -0.5 kPa and limiting the optimal installation clearance of the oil baffle to 0.30 mm to 0.60 mm. The -0.5 kPa negative pressure environment provides stable reverse pressure differential support for the oil film at the oil baffle clearance, enhancing the clearance's resistance to lubricating oil. The reasonable clearance of 0.30 mm to 0.60 mm ensures that under this negative pressure gradient, the flow channel resistance is sufficient to suppress leakage within the allowable range, while avoiding mechanical interference caused by too small a clearance or pressure differential failure caused by too large a clearance. This parameter-level solidification transforms complex fluid simulation results into directly executable engineering standards, enabling on-site commissioning to simultaneously achieve the dual goals of low leakage rate and high operational safety without relying on trial and error based on experience. This fundamentally solves the problem of recurring oil leakage caused by improper parameter matching in existing technologies.

[0154] The present invention provides an optimization method for preventing leakage in the lubricating oil system of a steam turbine generator set. First, by establishing a high-precision simulation model of the oil supply system, a reliable flow input is provided for the return oil flow analysis, ensuring the accuracy of the source of subsequent calculations. Second, based on the principle of mass conservation, a mathematical model of the flow state of the tubing is established, combined with a segmented calculation strategy for five operating conditions, to achieve precise quantification of complex two-phase flow states. This transforms the identification of pipe sections with obstructed negative pressure transmission from qualitative experience to quantitative diagnosis. On this basis, pipe diameter optimization calculations with a preset multi-level liquid level height ratio as the optimization objective not only meet the industry standard requirements for semi-pipe flow but also take into account the economic efficiency of engineering modifications. Simultaneously, VOF two-phase flow CFD is used... Simulation revealed the nonlinear mapping relationship between leakage rate and negative pressure and clearance, determined the optimal operating parameter range, avoided the risk of dynamic and static rubbing and significantly reduced the leakage rate. Finally, the optimized pipe diameter parameters were matched with the optimal operating negative pressure and the optimal installation clearance to form an anti-leakage optimization scheme. This multi-dimensional collaborative optimization fundamentally solved the technical problem of lubricating oil leakage and significantly improved the operational stability and reliability of the turbine generator set lubricating oil system.

[0155] This invention also provides an optimization system for preventing leaks in the lubricating oil system of a steam turbine generator set. Please refer to [link / reference]. Figure 11 The diagram shows the structure of the system, which may include: an oil supply simulation module 1101, an oil return flow analysis module 1102, a pipe diameter optimization module 1103, an oil baffle CFD simulation module 1104, and a leak prevention optimization scheme generation module 1105.

[0156] The oil supply simulation module 1101 is used to establish a simulation model of the lubricating oil supply system of the steam turbine generator set, and to calculate the oil supply flow rate of each bearing under different oil supply pressures based on the simulation model.

[0157] The return oil flow analysis module 1102 is used to establish a mathematical model of the flow state in the return oil pipe based on the principle of mass conservation and the calculated oil supply flow rate as input. By solving the mathematical model of the flow state in the return oil pipe, the liquid level height ratio of each section of the return oil pipe under different oil supply pressures is obtained. Based on the obtained liquid level height ratio and combined with the on-site bearing box pressure measurement data, the return oil pipe section where negative pressure transmission is obstructed is identified.

[0158] The pipe diameter optimization module 1103 is used to perform pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, with a preset liquid level height ratio as the optimization target, to obtain the optimal pipe diameter of the return oil pipe section where negative pressure transmission is obstructed.

[0159] The oil baffle CFD simulation module 1104 is used to establish a computational fluid dynamics (CFD) analysis model of the oil baffle. Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances is analyzed. Based on the lubricating oil leakage rate obtained from the analysis, the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle are determined.

[0160] The anti-leakage optimization scheme generation module 1105 is used to generate an overall anti-leakage optimization scheme for the lubricating oil system based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, for the purpose of optimizing the anti-leakage of the lubricating oil system.

[0161] In one possible implementation, the oil supply simulation module 1101 may include: a three-dimensional solid model construction submodule, a simulation model construction submodule, a simulation model verification submodule, and a simulation model correction submodule.

[0162] The 3D solid model construction submodule is used to construct a 3D solid model of the lubricating oil supply system based on the design drawings of the steam turbine generator set lubricating oil system.

[0163] The simulation model construction submodule is used to construct a preliminary simulation model of the lubricating oil supply system based on the geometric parameters of the three-dimensional solid model.

[0164] The simulation model verification submodule is used to verify the preliminary simulation model using the oil supply flow data of each bearing measured on site. If the verification is successful, the preliminary simulation model is determined as the final simulation model.

[0165] The simulation model correction submodule is used to correct the initial simulation model if it fails the verification.

[0166] The simulation model verification submodule is also used to re-verify the corrected simulation model using the on-site measured oil supply flow data of each bearing. If the verification is successful, the corrected simulation model will be determined as the final simulation model.

[0167] In one possible implementation, the simulation model verification submodule, when verifying the preliminary simulation model using field-measured oil supply flow data for each bearing, is specifically used for:

[0168] The oil supply flow rate of each bearing under different oil supply pressures is calculated based on the preliminary simulation model to obtain the simulated oil supply flow rate of each bearing under different oil supply pressures. The simulated oil supply flow rate of each bearing under different oil supply pressures is compared with the corresponding field measured oil supply flow rate. If the deviations of each comparison are within the allowable range of the project, the preliminary simulation model is judged to have passed the verification; otherwise, the preliminary simulation model is judged to have failed the verification.

[0169] In one possible implementation, the return oil flow analysis module 1102, based on the principle of mass conservation and using the calculated oil supply flow rate as input, establishes a mathematical model of the flow state within the return oil pipe. By solving this mathematical model, it obtains the percentage of liquid level in each section of the return oil pipe under different supply pressures. Specifically, this is used for:

[0170] Using the calculated oil supply flow rate as the input for the return flow rate, the driving force and resistance of the return oil pipe flow are analyzed. The driving force is the superposition of the component of fluid gravity along the pipe direction and the pressure gradient of the negative pressure fan, and the resistance is the frictional resistance along the pipe. Combining the geometric characteristics of the packaged oil pipe structure of the return oil pipe, the cross-sectional area and wetted perimeter of the return oil pipe are calculated segment by segment. Based on the calculated cross-sectional area and wetted perimeter, the balance equation of driving force and resistance is established. The balance equation is solved numerically to obtain the liquid level height ratio of each pipe segment of the return oil pipe under different oil supply pressures.

[0171] In one possible implementation, the return oil pipe is a nested structure consisting of a lubricating oil pipe and a top shaft oil pipe inside the return oil pipe.

[0172] The return oil flow analysis module 1102, when calculating the cross-sectional area and wetted perimeter of the return oil pipe in segments by combining the geometric characteristics of the packaged oil pipe structure, is specifically used for:

[0173] Based on the relationship between the liquid level and the position of the inner tube of the return oil pipe, various working conditions are divided, including: the liquid level does not contact the jacking oil pipe, the liquid level contacts the jacking oil pipe but is not completely submerged, the jacking oil pipe is completely submerged but does not contact the lubricating oil pipe, the liquid level contacts the lubricating oil pipe but is not completely submerged, and the lubricating oil pipe is completely submerged; the cross-sectional area and wetted perimeter of the return oil pipe are calculated for each working condition.

[0174] In one possible implementation, when the return oil flow analysis module 1102 identifies the return oil pipe section where negative pressure transmission is obstructed, based on the obtained liquid level height percentage and combined with the on-site bearing box pressure measurement data, it is specifically used for:

[0175] Obtain the percentage of liquid level in each return oil pipe section within the target oil supply pressure range; determine the return oil pipe section where the percentage of liquid level exceeds the preset liquid level percentage threshold and the corresponding bearing box measured pressure is higher than the preset negative pressure benchmark or the corresponding bearing box measured pressure is in a slightly positive pressure state as the negative pressure transmission obstruction.

[0176] In one possible implementation, when the pipe diameter optimization module 1103 performs pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, with a preset liquid level height ratio as the optimization target, and obtains the optimal pipe diameter for the return oil pipe section where negative pressure transmission is obstructed, it is specifically used for:

[0177] From the pipe sections where negative pressure transmission is obstructed, the pipe sections to be optimized are determined according to the preset pipe section selection rules; with the preset multi-level liquid level height ratio as the optimization target, the pipe diameter of the pipe sections to be optimized is calculated to obtain the optimal pipe diameter that meets the optimization target.

[0178] In one possible implementation, the pipe segment selection rules include: for return branch pipes, selecting the inlet pipe segment; for return main pipes, selecting pipe segments in order of priority from small to large pipe diameter; and selecting pipe segments in order of priority from large to small oil supply flow rate, from small to large pipe slope, and from high to low liquid level height percentage.

[0179] In one possible implementation, the optimal operating negative pressure of the bearing housing is -0.5 kPa, and the optimal installation clearance range of the oil baffle is 0.30 mm to 0.60 mm.

[0180] This invention provides a leak-proof optimization device for the lubricating oil system of a steam turbine generator set. By incorporating the optimization of the return oil pipe diameter, the control of the bearing housing negative pressure, and the oil baffle installation clearance into a unified framework, and generating an overall leak-proof optimization scheme based on the optimal pipe diameter, the optimal operating negative pressure, and the optimal installation clearance, the device fundamentally prevents lubricating oil leakage and improves the operational stability and reliability of the steam turbine generator set's lubricating oil system.

[0181] This invention also provides an electronic device, which may include at least one processor and a memory connected to the processor.

[0182] The memory is used to store computer programs, and the processor is used to execute the computer programs so that the electronic device can implement the steps of the anti-leakage optimization method for the steam turbine generator set lubrication oil system provided in the above embodiments.

[0183] This invention also provides a computer storage medium carrying one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement the steps of the anti-leakage optimization method for the steam turbine generator set lubrication oil system provided in the above embodiments.

[0184] This invention also provides a computer program product, including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement the steps of the turbine generator set lubrication oil system anti-leakage optimization method provided in the above embodiments.

[0185] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the accompanying drawings of the device embodiments provided by this invention, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0186] Through the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus necessary general-purpose hardware, and of course, it can also be implemented by special-purpose hardware including application-specific integrated circuits, special-purpose CPUs, special-purpose memory, special-purpose components, etc. Generally, any function performed by a computer program can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be diverse, such as analog circuits, digital circuits, or special-purpose circuits. However, for the present invention, software program implementation is more often the preferred implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk, or optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, training equipment, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0187] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product.

[0188] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, training device, or data center to another website, computer, training device, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

Claims

1. A method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set, characterized in that, include: A simulation model of the lubricating oil supply system of a steam turbine generator set is established, and the oil supply flow rate of each bearing under different oil supply pressures is calculated based on the simulation model. Based on the principle of mass conservation, a mathematical model of the flow state in the return oil pipe is established using the calculated oil supply flow rate as input. By solving the mathematical model of the flow state in the return oil pipe, the proportion of liquid level height in each section of the return oil pipe under different oil supply pressures is obtained. Based on the obtained proportion of liquid level height and combined with the on-site bearing box pressure measurement data, the return oil pipe section where negative pressure transmission is obstructed is identified. Using a preset liquid level height ratio as the optimization target, the pipe diameter of the return oil pipe section where negative pressure transmission is obstructed is optimized to obtain the optimal pipe diameter of the return oil pipe section where negative pressure transmission is obstructed. A computational fluid dynamics (CFD) analysis model for the oil baffle is established. Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances is analyzed. Based on the lubricating oil leakage rate obtained from the analysis, the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle are determined. Based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, an overall optimization scheme for preventing leakage of the lubricating oil system is generated for the purpose of optimizing the leakage prevention of the lubricating oil system.

2. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 1, characterized in that, The establishment of a simulation model for the lubricating oil supply system of the steam turbine generator set includes: Based on the design drawings of the steam turbine generator set lubrication oil system, construct a three-dimensional solid model of the lubrication oil supply system; Based on the geometric parameters of the three-dimensional solid model, a preliminary simulation model of the lubricating oil supply system is constructed. The preliminary simulation model was verified using on-site measured oil supply flow data for each bearing. If the verification passes, the preliminary simulation model is determined as the final simulation model; if the verification fails, the preliminary simulation model is modified, and the modified simulation model is re-verified using the on-site measured oil supply flow data of each bearing. If the verification passes, the modified simulation model is determined as the final simulation model.

3. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 2, characterized in that, The verification of the preliminary simulation model using on-site measured oil supply flow data for each bearing includes: Based on the preliminary simulation model, the oil supply flow rate of each bearing under different oil supply pressures is calculated, and the simulated oil supply flow rate of each bearing under different oil supply pressures is obtained. The simulated oil supply flow rate of each bearing under different oil supply pressures is compared with the corresponding on-site measured oil supply flow rate. If all comparison deviations are within the allowable range for engineering, the preliminary simulation model is deemed to have passed verification; otherwise, the preliminary simulation model is deemed to have failed verification.

4. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 1, characterized in that, Based on the principle of mass conservation, a mathematical model of the flow state within the return oil pipe is established using the calculated oil supply flow rate as input. By solving this mathematical model, the percentage of liquid level in each section of the return oil pipe under different oil supply pressures is obtained, including: Using the calculated oil supply flow rate as the return oil flow rate input, the driving force and resistance of the return oil pipe flow are analyzed. The driving force is the superposition of the component of fluid gravity along the pipe direction and the pressure gradient of the negative pressure fan, and the resistance is the frictional resistance along the pipe. Based on the geometric characteristics of the tubing structure of the return oil pipe, the cross-sectional area and wetted perimeter of the return oil pipe are calculated in segments, and the balance equation of driving force and resistance is established based on the calculated cross-sectional area and wetted perimeter. The equilibrium equation is solved numerically through iteration to obtain the percentage of liquid level in each section of the return oil pipe under different oil supply pressures.

5. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 4, characterized in that, The oil return pipe has a nested structure consisting of a lubricating oil pipe and a top shaft oil pipe inside the oil return pipe. The geometric characteristics of the combined return oil pipe and the sleeved oil pipe structure are used to calculate the cross-sectional area and wetted perimeter of the return oil pipe in segments, including: Based on the relationship between the liquid level and the position of the inner tube of the return oil pipe, various working conditions are defined, including: the liquid level does not contact the top shaft oil pipe, the liquid level contacts the top shaft oil pipe but is not completely submerged, the top shaft oil pipe is completely submerged but does not contact the lubricating oil pipe, the liquid level contacts the lubricating oil pipe but is not completely submerged, and the lubricating oil pipe is completely submerged. The cross-sectional area and wetted perimeter of the return oil pipe were calculated for each of the aforementioned operating conditions.

6. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 1, characterized in that, The process of identifying return oil pipe sections where negative pressure transmission is obstructed, based on the obtained liquid level height percentage and combined with on-site bearing box pressure measurement data, includes: Obtain the percentage of liquid level in each return oil pipe section within the target oil supply pressure range; The pipe section where the liquid level height ratio exceeds the preset liquid level height ratio threshold and the corresponding bearing box measured pressure is higher than the preset negative pressure benchmark or the corresponding bearing box measured pressure is in a slightly positive pressure state is identified as the return oil pipe section where negative pressure transmission is obstructed.

7. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 1, characterized in that, The step of optimizing the pipe diameter of the return oil pipe section where negative pressure transmission is obstructed, using a preset liquid level height ratio as the optimization target, includes: From each of the pipe segments where negative pressure transmission is obstructed, the pipe segments to be optimized are determined according to the preset pipe segment selection rules; Using the preset multi-level liquid level height ratio as the optimization target, the pipe diameter of the pipe section to be optimized is calculated to obtain the optimal pipe diameter that meets the optimization target.

8. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 7, characterized in that, The pipe segment selection rules include: For the return branch pipe, select the inlet pipe section; For the return oil header, pipe sections are selected according to priority order from smallest to largest pipe diameter; Pipe sections were selected according to priority order: from largest to smallest oil supply flow rate, from smallest to largest pipeline slope, and from highest to lowest liquid level height percentage.

9. The method for optimizing the anti-leakage of the lubricating oil system of a steam turbine generator set according to claim 1, characterized in that, The optimal operating negative pressure of the bearing housing is -0.5 kPa, and the optimal installation clearance range of the oil baffle is 0.30 mm to 0.60 mm.

10. A leak-proof optimization system for the lubricating oil system of a steam turbine generator set, characterized in that, include: Oil supply simulation module, oil return flow analysis module, pipe diameter optimization module, oil baffle CFD simulation module, and leak prevention optimization scheme generation module; The oil supply simulation module is used to establish a simulation model of the lubricating oil supply system of the steam turbine generator set, and to calculate the oil supply flow rate of each bearing under different oil supply pressures based on the simulation model. The oil return flow analysis module is used to establish a mathematical model of the flow state in the oil return pipe based on the principle of mass conservation and the calculated oil supply flow rate as input. By solving the mathematical model of the flow state in the oil return pipe, the liquid level height ratio of each section of the oil return pipe under different oil supply pressures is obtained. Based on the obtained liquid level height ratio and combined with the on-site bearing box pressure measurement data, the oil return pipe section where negative pressure transmission is obstructed is identified. The pipe diameter optimization module is used to perform pipe diameter optimization calculations on the return oil pipe section where negative pressure transmission is obstructed, with a preset liquid level height ratio as the optimization target, to obtain the optimal pipe diameter of the return oil pipe section where negative pressure transmission is obstructed. The oil baffle CFD simulation module is used to establish a computational fluid dynamics (CFD) analysis model of the oil baffle. Based on the CFD analysis model, the lubricating oil leakage rate under different bearing housing operating negative pressures and different oil baffle installation clearances is analyzed. Based on the lubricating oil leakage rate obtained from the analysis, the optimal operating negative pressure of the bearing housing and the optimal installation clearance of the oil baffle are determined. The leak prevention optimization scheme generation module is used to generate an overall leak prevention optimization scheme for the lubricating oil system based on the optimal pipe diameter, the optimal operating negative pressure of the bearing housing, and the optimal installation clearance of the oil baffle, for the purpose of leak prevention optimization of the lubricating oil system.

Images