Thrust calculation method, evaluation method for balance piston diameter, and thrust calculation system

Abstract

This invention discloses a thrust calculation method, a method for evaluating the diameter of a balance piston, and a thrust calculation system. The thrust calculation method includes the following steps: S11, classifying all parts of an axial-flow steam turbine that generate axial thrust into several independent basic thrust units; S12, encapsulating the thrust algorithms of each basic thrust unit into a thrust calculation module; S13, calling the basic thrust units as needed to construct a thrust model and obtaining the structural parameters and thermodynamic data of each basic thrust unit in the thrust model; S14, inputting the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module; S15, the thrust calculation module calculates the thrust of each basic thrust unit in the thrust model and the total thrust. This invention can accurately calculate the axial thrust of any axial-flow steam turbine, is applicable to various turbine models, and provides a data basis for determining reasonable balance piston dimensions and selecting appropriate thrust bearings.

Description

Technical Field

[0001] This invention relates to the field of axial-flow steam turbines, specifically to a thrust calculation method, a method for evaluating the diameter of the balance piston, and a thrust calculation system. Background Technology

[0002] For axial-flow steam turbines, during operation, as the steam expands and performs work from the high-pressure end to the low-pressure end, the steam pressure difference on both sides of the protruding rotor components generates an axial thrust from the high-pressure end to the low-pressure end, causing axial displacement of the turbine. For multi-stage steam turbines, the axial thrust is the sum of the axial thrust of each stage, and its value is considerable, making it one of the problems that must be solved for the safe operation of the turbine unit. Therefore, accurate calculation and analysis of the turbine's axial thrust, and subsequently the development of reasonable balancing methods and the selection of appropriate thrust bearings, are of great significance.

[0003] Currently, the common method for calculating the axial thrust of steam turbines is to manually input each structural and thermodynamic data of the turbine, and then calculate the thrust based on the corresponding thrust calculation formula. However, in reality, due to various operating conditions, each requiring a total thrust calculation, and for multiple turbines, the thermodynamic data for each row of blades also needs to be input individually before thrust calculation. Furthermore, because different turbine models differ, the specific calculation process for calculating the total thrust of different turbines is not entirely the same. Therefore, when calculating axial thrust, the repetitive workload of manually inputting the turbine's structural and thermodynamic data is large, tedious, prone to errors, and difficult to verify. In addition, current turbine thrust calculation algorithms are not precise enough and have low accuracy.

[0004] Therefore, it is essential to propose a simple, easy-to-operate method for calculating the thrust of steam turbines that is applicable to different models. Summary of the Invention

[0005] The purpose of this invention is to propose a universal method for calculating the axial thrust of an axial-flow steam turbine, enabling accurate calculation of the axial thrust, helping technicians to discover the thrust variation law of the unit, ensuring that the thrust under the worst operating conditions is within the allowable range; facilitating technicians to design thrust balancing schemes and balancing piston dimensions; and assisting relevant personnel in verifying the feasibility of the thrust bearings used in the unit.

[0006] To achieve the above objectives, this invention proposes a thrust calculation method applicable to various axial-flow steam turbine units. Based on the actual operating conditions and steam characteristics of axial-flow steam turbines, this method achieves accurate calculation of axial thrust through mathematical model encapsulation and comprehensive acquisition of various parameters, including the following steps:

[0007] S11. All parts of the axial-flow steam turbine that can generate axial thrust are classified into several independent basic thrust units.

[0008] S12. The thrust algorithms of various basic thrust units are encapsulated into the thrust calculation module respectively;

[0009] S13. Call the basic thrust units as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model; wherein, the types and quantities of the basic thrust units in the thrust model can be freely combined;

[0010] S14. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module;

[0011] S15. The thrust calculation module calls the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model, and calculates the total thrust of each basic thrust unit.

[0012] Optionally, in step S11, all parts of the axial-flow turbine that can generate axial thrust are classified into several independent basic thrust units, namely: rotor steps, shaft end steam seals, pressure stages, last stage long blades, and regulating stages.

[0013] Each basic thrust unit is further subdivided into several calculation parts, specifically:

[0014] The pressure stage basic thrust unit includes: moving blade airfoil, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal;

[0015] The final stage long blade basic thrust unit includes: moving blade airfoil, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal;

[0016] The regulating stage basic thrust unit includes: moving blade airfoil, moving blade shroud and steam seal, a wheel between the moving blade root and the radial steam seal, and a wheel between the radial steam seal and the rotor.

[0017] Optionally, step S13 includes:

[0018] Step S131: For a given specific axial-flow turbine model, call the basic thrust unit to construct a thrust model corresponding to the specific axial-flow turbine model, and obtain the structural parameters of each basic thrust unit in the thrust model;

[0019] S132. Given the operating conditions of the steam turbine, the thermodynamic data of each basic thrust unit in the thrust model are obtained through thermodynamic system thermal balance calculation.

[0020] The thermodynamic data of the rotor step foundation thrust unit includes the static pressure at the step.

[0021] The thermodynamic data of the shaft end steam seal foundation thrust unit includes inlet and outlet pressures;

[0022] The thermodynamic data of the pressure stage basic thrust unit includes the outlet static pressure, inlet and outlet axial velocity, outlet specific volume, and stage inlet and outlet static pressure for each row of blades.

[0023] The thermodynamic data of the last-stage long blade basic thrust unit includes the static pressure at the blade tip, blade body, and blade root on the inlet side of the moving blade, the static pressure on the outlet side of the moving blade, the axial velocity at the inlet of the moving blade, the specific volume at the inlet and outlet of the moving blade, and the static pressure before the stationary blade steam seal.

[0024] The thermodynamic data of the basic thrust unit of the regulating stage includes the static pressure at the outlet blade tip, blade body, and blade root of each open nozzle group, the partial steam inlet degree corresponding to each nozzle group, and the static pressure behind the moving blade corresponding to each nozzle group.

[0025] Optionally, in step S13, for the thrust model, it is also necessary to obtain the steam flow direction, the mark of the balance piston, and the mark of the cylinder information in the thrust model.

[0026] Optionally, the thrust calculation module encapsulates thrust algorithms for various basic thrust units, including two most basic thrust algorithms: thrust caused by the pressure difference on both sides of the part and thrust caused by the difference in the diameter of the force-bearing surface.

[0027] The thrust calculation module also employs the following refined algorithm:

[0028] For the shaft end steam seal foundation thrust unit, different steam seal types correspond to different algorithms;

[0029] For the blade profile of the moving blade in the pressure stage basic thrust unit, the influence of the airflow force acting on the moving blade is considered;

[0030] For the blade shroud and steam seal in the pressure stage basic thrust unit, different algorithms are used to calculate the equivalent shroud height for different types of shrouds.

[0031] For the aforementioned last-stage long blade basic thrust unit, the thrust is calculated in segments, divided into three segments: the shroud, the airfoil, and the blade root. Different static pressure values ​​are used for each segment to calculate the thrust.

[0032] For the basic thrust unit of the regulating stage, different pressure point values ​​are used depending on whether the actual structure has a root radial steam seal or not. Based on the distribution of nozzle outlet static pressure along the blade height, different nozzle outlet pressure points are used to calculate the thrust at different locations. Furthermore, depending on whether the regulating stage wheel disc has a balance hole or not, different values ​​are used for the inlet pressure of the wheel disc section between the radial steam seal and the rotor.

[0033] Optionally, the axial thrust calculation method further includes: setting the pressure value of all thermodynamic data in S13 to a first set value, and checking whether the total thrust obtained in S15 is 0, so as to verify whether the structural parameters of the thrust model are continuous.

[0034] In another aspect, the present invention also proposes a method for evaluating the diameter of the balance piston in an axial-flow steam turbine, comprising the following steps:

[0035] S21. All parts of the axial-flow steam turbine that generate axial thrust are classified into several independent basic thrust units.

[0036] S22. The thrust algorithms of various basic thrust units are encapsulated into the thrust calculation module respectively;

[0037] S23. Call the basic thrust unit as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model;

[0038] S24. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module; wherein, in the structural parameters of each basic thrust unit in the thrust model, the diameter of the balance piston is set as a guide value to prompt the thrust calculation module to calculate the diameter value of the balance piston.

[0039] S25. The thrust calculation module calculates the thrust of each basic thrust unit in the thrust model by calling the corresponding thrust algorithm according to the structural parameters and thermodynamic data of each basic thrust unit, and then calculates the balance piston diameter value when the total thrust is the second set value.

[0040] Optionally, the method for evaluating the balance piston diameter further includes: repeating steps S21 to S25 for various test conditions, calculating the balance piston diameter value under various test conditions, and then determining the final design reference value of the balance piston diameter according to a certain mechanism.

[0041] Optionally, the mechanism is to calculate the average or median of the balance piston diameter under various test conditions as the design reference value for the balance piston diameter.

[0042] This invention also proposes a thrust calculation system for implementing the aforementioned thrust calculation method and the aforementioned method for evaluating the diameter of the balanced piston. The thrust calculation system includes a model generation module and a thrust calculation module. The model generation module includes all basic thrust units, which can be combined as needed to construct a thrust model. The thrust calculation module has built-in thrust algorithms for all the basic thrust units, and can calculate the thrust of each basic thrust unit in the thrust model, as well as the total thrust of the thrust model.

[0043] The present invention also proposes a computer-readable storage medium storing a computer program thereon, wherein the computer program, when running, controls the electronic device on which the readable storage medium is located to execute the axial thrust calculation method or the balanced piston diameter evaluation method.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] The thrust calculation method disclosed in this solution is based on the actual operating conditions and steam characteristics of axial-flow steam turbines. Through mathematical model encapsulation and comprehensive acquisition of various parameters, it achieves accurate calculation and result display of axial thrust. It can be applied to the axial thrust calculation of various axial-flow steam turbine units, helping technicians to discover the thrust variation law of the unit and ensure that the thrust under the worst operating conditions is within the allowable range; it can also help check the continuity of rotor structure data.

[0046] The method for evaluating the diameter of the balance piston disclosed in this scheme can design and evaluate the diameter of the balance piston based on accurate axial thrust calculation results, which helps to accelerate the design process and improve the operational stability of axial flow steam turbines. Attached Figure Description

[0047] Figure 1 This is a flowchart of a method for calculating the axial thrust of an axial-flow steam turbine according to the present invention;

[0048] Figure 2 This is a schematic diagram of the turbine blade structure;

[0049] Figure 3 This is a flowchart of a method for evaluating the diameter of a balance piston in an axial-flow steam turbine according to the present invention.

[0050] Figure label:

[0051] 1 represents the top of the steam inlet side vane;

[0052] 2 represents the steam inlet side blade;

[0053] 3 represents the inlet side blade root;

[0054] 4 represents the top of the steam outlet side vane;

[0055] 5 represents the steam outlet side blade;

[0056] 6 represents the root of the steam outlet blade;

[0057] 7 represents the blade. Detailed Implementation

[0058] The technical solutions, structural features, achieved objectives, and effects of the present invention will be described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0059] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0060] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0061] This embodiment discloses a method for calculating the axial thrust of an axial-flow steam turbine, applicable to calculating the axial thrust of an axial-flow steam turbine, such as... Figure 1 As shown, the axial thrust calculation method includes the following steps:

[0062] S11. All parts of the axial-flow steam turbine that can generate axial thrust are classified into several independent basic thrust units, and the complex basic thrust units are further refined into multiple thrust calculation parts.

[0063] S12. Encapsulate the thrust algorithms of various basic thrust units and thrust calculation parts into the thrust calculation module respectively;

[0064] S13. Call the basic thrust units as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model; wherein, the types and quantities of the basic thrust units in the thrust model can be freely combined;

[0065] S14. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module;

[0066] S15. The thrust calculation module calls the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model, and calculates the total thrust of each basic thrust unit.

[0067] In step S11 above, all components of the axial-flow turbine capable of generating axial thrust are categorized into several independent basic thrust units: rotor steps, shaft end steam seals, pressure stages, last-stage long blades, and regulating stages. Furthermore, each basic thrust unit can be further subdivided into several calculation components. Specifically: the pressure stage can be further subdivided into multiple thrust calculation components, namely: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the last-stage long blades can be further subdivided into multiple thrust calculation components, namely: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the regulating stage can be further subdivided into multiple thrust calculation components, namely: moving blade profile, moving blade shroud and steam seal, the impeller between the moving blade root and the radial steam seal, and the impeller between the radial steam seal and the rotor. Table 1 below visually represents the composition of the thrust calculation components for each basic thrust unit.

[0068] Table 1 Thrust Unit Disassembly

[0069]

[0070] In step S13, the various basic thrust units from S11 are called upon as needed to construct the thrust model. This means that in actual use, the types and quantities of each basic thrust unit can be flexibly combined and freely arranged according to actual needs to construct the required thrust model. It is precisely because this invention classifies all thrust-generating parts of an axial-flow steam turbine into various basic thrust units that it is easy to call and combine them to construct a thrust model according to requirements. This makes the method applicable to various axial-flow steam turbine models, improving the scope and flexibility of the invention.

[0071] In addition, since the thrust of each basic thrust unit needs to be calculated based on the pressure value and the area of ​​force application, step S13 also includes: obtaining the structural data and thermal data of each basic thrust unit in the thrust model.

[0072] Specifically, step S13 further includes the following steps:

[0073] Step S131: For a given specific axial-flow turbine model, call the basic thrust unit to construct a thrust model corresponding to the specific axial-flow turbine model, and obtain the structural parameters of each basic thrust unit in the thrust model;

[0074] Step S132: Given the turbine operating conditions, obtain the thermal data of each basic thrust unit in the thrust model through thermal balance calculation of the thermal system.

[0075] The pressure values ​​of each thrust unit are derived from the thermodynamic data obtained after thermal balance calculations of the thermodynamic system. These thermal balance calculations involve a comprehensive analysis and calculation of the entire thermodynamic cycle of the steam turbine. Based on given turbine operating conditions, such as load, initial steam parameters (pressure, temperature), and exhaust parameters, the calculations determine the energy distribution and conversion within the system, ensuring that the entire thermodynamic system adheres to the law of conservation of energy during design and operation, thus achieving efficient and stable operation. Table 2 below shows the required thermodynamic data for each thrust unit.

[0076] Table 2. Thermodynamic parameters required for thrust calculation

[0077] Basic thrust unit thermal parameters Rotor steps static pressure at the step Shaft end steam seal Import and export pressure pressure level The static pressure at the outlet of each row of blades, the axial velocity at the inlet and outlet, the specific volume at the outlet, and the static pressure at the inlet and outlet of the stage group. Long blades in the final stage Static pressure at the inlet side of the moving blade (blade tip, blade body, and blade root), static pressure at the outlet side of the moving blade, axial velocity at the inlet of the moving blade, specific volume at the inlet and outlet of the moving blade, and static pressure before the stationary blade steam seal. Regulation level The static pressure at the outlet blade tip, blade body, and blade root of each opened nozzle group; the corresponding partial steam inlet pressure for each nozzle group; and the static pressure behind the moving blade for each nozzle group.

[0078] The thrust composition of the pressure stage is the same as that of the long blade. However, in the aforementioned final-stage long blade basic thrust unit, the static pressure is differentiated between the blade tip, blade body, and blade root on the inlet side because: long blades are relatively long, and the pressure distribution at the blade tip, blade body, and blade root differs to some extent. Therefore, it is necessary to use corresponding pressures for thrust calculations at different locations. Figure 2 For example, Figure 2 The diagram shows the structure of blade 7. When it is a pressure stage, the inlet static pressure at the blade tip 1, blade body 2, and blade root 3 on the inlet side is taken as the inlet static pressure at the mid-diameter of the moving blade. For long blades, the inlet static pressure at the blade tip, the mid-diameter inlet static pressure, and the blade root inlet static pressure are taken respectively. Because the static pressure at the blade outlet is relatively uniformly distributed along the blade height, the static pressure at the blade tip 4, blade body 5, and blade root 6 on the outlet side is uniformly taken as the outlet static pressure at the mid-diameter. Then, the root reaction degree and the tip reaction degree are calculated according to the static pressure reaction degree, and then the inlet static pressure at the blade root and blade tip are calculated. The following is the algorithm for the static pressure at the blade tip and blade root on the inlet side of the moving blade:

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] in, Indicates the degree of static pressure reaction. This indicates the inlet static pressure at the median diameter of the moving blade. This indicates the outlet static pressure at the median diameter of the moving blade. This indicates the inlet static pressure at the center diameter of the stationary blade. Indicates the degree of reaction at the root. Indicates the effective median diameter of the throat of the leaf. Indicates the effective height of the blade throat. Indicates the degree of reaction at the top. This indicates the inlet static pressure at the root of the moving blade. This indicates the inlet static pressure at the tip of the moving blade.

[0085] In step S13, the structural parameters of the thrust unit are used to calculate the force-bearing area of ​​the axial thrust. Table 3 below shows the structural parameters required for each thrust unit.

[0086] Table 3 Structural parameters required for thrust calculation

[0087]

[0088] Furthermore, in step S13, for the thrust model, in addition to the structural and thermodynamic parameters of the basic thrust unit, it is also necessary to obtain the steam flow direction, the marking of the balancing piston, and the marking of the cylinder information. The steam flow direction is either co-current or counter-current, used to determine the positive or negative value of the thrust; for example, rightward flow is defined as a positive value. The marking of the cylinder information is equivalent to grouping the basic thrust units. Basic thrust units belonging to the same cylinder are marked with the same group name, such as Casing1. In subsequent step S15, the total thrust of the basic thrust units included in each cylinder can be calculated. The marking of the balancing piston refers to the fact that the shaft end steam seal and the left and right rotor steps belonging to the same group of balancing pistons are marked with the same balancing piston number, such as BP1 (balancing piston). Setting this balancing piston marking is beneficial for subsequent evaluation of the balancing piston diameter.

[0089] The thrust calculation module encapsulates thrust algorithms for various basic thrust units, including two fundamental thrust algorithms: one for thrust caused by the pressure difference between the two sides of a component and the other for thrust caused by the difference in the diameter of the force-bearing surface. The specific calculation methods are as follows:

[0090] The thrust caused by the pressure difference on both sides of a certain part: , , TCPD represents the thrust caused by the pressure difference between the left and right sides of the part, LSP represents the static pressure on the left side, LSFA represents the force-bearing area on the left side, RSP represents the static pressure on the right side, RSFA represents the force-bearing area on the right side, LSOD represents the outer diameter on the left side, LSID represents the inner diameter on the left side, RSOD represents the outer diameter on the right side, and RSID represents the inner diameter on the right side.

[0091] For the thrust caused by the difference in diameter of a certain force-bearing surface: , Where ToS represents the thrust caused by the difference in diameter of the force-bearing surface, SP represents the static pressure at the force-bearing surface, AFBA represents the annular force-bearing area, OD represents the outer diameter of the force-bearing surface, and ID represents the inner diameter of the force-bearing surface.

[0092] The code shown below encapsulates and stores the two basic algorithms mentioned above in the thrust calculation module, which can then be called when calculating the thrust of each basic thrust unit.

[0093]

[0094]

[0095] In step S15, the thrust calculation module calls the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model, and then calculates their sum to obtain the axial thrust of the axial-flow turbine. Different basic thrust units have different thrust calculation methods, and the thrust calculation module's thrust algorithm also employs the following refined algorithms: For the shaft end steam seal basic thrust unit, different steam seal types correspond to different algorithms; for the moving blade profile in the pressure stage basic thrust unit, the influence of the airflow force acting on the moving blade needs to be considered; for the moving blade shroud and steam seal in the pressure stage basic thrust unit, different algorithms are used to calculate the equivalent shroud height for different types of shrouds (the same applies to the moving blade shrouds in other thrust units); for the last-stage long-blade basic thrust unit, due to the long... Due to the relatively long blades and significant pressure differences at the blade tip, blade body, and blade root, a segmented thrust calculation is adopted to consider the pressure distribution along the blade height. This involves dividing the thrust into three segments: the shroud, the airfoil, and the blade root, with different static pressure values ​​applied to each segment. For the regulating stage's basic thrust unit, different pressure points are used depending on whether the actual structure has a root radial steam seal. Furthermore, based on the distribution of nozzle outlet static pressure along the blade height, different nozzle outlet pressure points are used to calculate thrust at different locations. Finally, depending on whether the regulating stage impeller has a balancing hole, different inlet pressure values ​​are applied to the radial steam seal and the impeller section between the rotor and the impeller. Through these refined calculations, the actual structure of the turbine and the working fluid flow characteristics are fully considered, resulting in a more accurate calculated axial thrust.

[0096] In the calculation of thrust acting on the moving blade profile in the pressure stage and the last stage long blade, in addition to the thrust generated by the static pressure difference before and after the moving blade, the thrust F generated by the change in axial momentum of steam passing through the moving blade is also considered. a (That is, the thrust caused by airflow force), the calculation process is as follows:

[0097]

[0098] ( )

[0099] +( )

[0100] in, G For the mass flow rate through this stage, υ 1、 υ2 represents the specific volume of steam entering the moving blade and the specific volume of steam exiting the moving blade, respectively; c1 and c2 represent the relative velocities of steam entering the moving blade and the relative velocities of steam exiting the moving blade, respectively; and α1 and α2 represent the relative steam flow angles at the inlet and outlet of the moving blade, respectively. , These are the axial velocities of the steam entering the moving blades and the axial velocities of the steam exiting the moving blades, respectively. , These are the force-bearing areas on the inlet side and the force-bearing areas on the outlet side, respectively, and p1 and p2 are the static pressure on the inlet side and the static pressure on the outlet side, respectively.

[0101] The thrust calculation formula for each component is the product of the component's force-bearing area and the pressure difference before and after the component. The force-bearing area can be determined based on structural parameters, and the pressure difference can be determined based on thermodynamic data. These are both commonly used calculation methods. The focus of this scheme is not the most basic mathematical model mentioned above, but rather to classify all parts on the turbine main shaft that generate axial thrust into several independent thrust units in a modular way. The thrust units can be freely arranged, and the units can be flexibly combined to construct the thrust model according to the project situation. It is applicable to various turbine models. Therefore, the specific calculation method of the thrust of each basic thrust unit will not be described in detail here.

[0102] Furthermore, the axial thrust calculation method for the axial-flow steam turbine in this embodiment can also be used to verify whether the structural parameters of the thrust model are continuous. Specifically: the pressure values ​​of all thermodynamic data in S13 are set to a first set value, and the total thrust obtained in S14 is checked to see if it is 0. The magnitude of the first set value can be set; in this embodiment, the first set value is 1. Furthermore, the verification results of the structural parameters are also displayed to remind relevant personnel of the rationality of the structural dimensions. For some thrust calculation formulas, such as the aforementioned thrust F... a In the calculation formula, it is to use and Set to 1, that is, set the steam specific volume and steam axial velocity to 1.

[0103] The above-mentioned method for calculating the axial thrust of axial-flow steam turbines covers all necessary types of basic thrust units, and the basic thrust units can be freely arranged. The basic thrust units can be flexibly combined to construct a thrust model according to the project situation. Therefore, this invention is not limited by the type of turbine and is applicable to the thrust analysis of any axial-flow steam turbine unit, with good versatility.

[0104] In another embodiment, a method for evaluating the diameter of a balanced piston is also disclosed, such as... Figure 3 As shown, it includes the following steps:

[0105] S21. All parts of the axial-flow steam turbine that generate axial thrust are classified into several independent basic thrust units.

[0106] S22. The thrust algorithms of various basic thrust units are encapsulated into the thrust calculation module respectively;

[0107] S23. Call the basic thrust unit as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model;

[0108] S24. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module;

[0109] In the structural parameters of each basic thrust unit of the thrust model, the diameter of the balance piston is set as a guide value to prompt the thrust calculation module to calculate the diameter value of the balance piston. The specific value of the guide value is not specified and can be set according to the actual situation. In this embodiment, the guide value is set to -999.

[0110] S25. The thrust calculation module calculates the thrust of each basic thrust unit in the thrust model by calling the corresponding thrust algorithm based on the structural parameters and thermal data of each basic thrust unit. Then, it calculates the balance piston diameter value when the total thrust is equal to a second set value. That is, the balance piston is designed with reference to this balance piston diameter value to obtain better stability. The value of the second set value can be selected according to the actual situation. In this embodiment, the second set value is 0.

[0111] Since the balance piston includes two bosses on the left and right (rotor step foundation thrust unit) and a steam seal in the middle (shaft end steam seal foundation thrust unit), the diameter of the balance piston is set as the guide value, that is, the rotor diameter of the shaft end steam seal foundation thrust unit, the right side diameter of the left boss, and the left side diameter of the right boss are all set as guide values.

[0112] Except for the difference in the diameter of the balance piston in S24, the above steps S21 to S24 are exactly the same as steps S11 to S14 of the above axial thrust calculation method.

[0113] Furthermore, this method can comprehensively consider different working conditions, calculate the balance piston diameter value under different test conditions multiple times, and then execute step S26 to determine the final balance piston diameter evaluation value according to a certain mechanism. The mechanism can be customized as needed, for example, calculating the average or median of the balance piston diameter values ​​under different test conditions as the design reference value for the balance piston diameter.

[0114] Finally, this invention also discloses a thrust calculation system for implementing the above-mentioned axial thrust calculation method and the method for evaluating the diameter of the balanced piston. The thrust calculation system includes a model generation module and a thrust calculation module. The model generation module includes all basic thrust units, which can be combined as needed to construct a thrust model. The thrust calculation module has built-in thrust algorithms for all the basic thrust units. The thrust calculation module can calculate the thrust of each basic thrust unit in the thrust model, as well as the total thrust of the thrust model.

[0115] In practical applications, when implementing the axial thrust calculation method, basic thrust units are freely combined in the model generation module as needed to generate a turbine thrust model that meets the requirements. This turbine thrust model is then input into the thrust calculation module, along with the structural and thermodynamic parameters of each basic thrust unit. The thrust calculation module calculates the thrust of each basic thrust unit and then calculates the total thrust of the entire turbine thrust model. Similarly, when implementing the method for evaluating the balance piston diameter, basic thrust units are freely combined in the model generation module as needed to generate a turbine thrust model that meets the requirements. This turbine thrust model is then input into the thrust calculation module, along with the structural and thermodynamic parameters of each basic thrust unit. The diameter of the balance piston is set as a guide value, and the thrust calculation module calculates the balance piston diameter when the total thrust is a second set value.

[0116] Based on the above-described axial thrust calculation method and balanced piston diameter evaluation method, this embodiment of the invention also proposes a computer-readable storage medium storing a computer program thereon. When the computer program is executed, it controls the electronic device containing the readable storage medium to perform the axial thrust calculation method or the balanced piston diameter evaluation method.

[0117] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for calculating the axial thrust of an axial-flow steam turbine, characterized in that, The process includes the following steps: S11. Classifying all parts of the axial-flow turbine that can generate axial thrust into several independent basic thrust units, namely: rotor steps, shaft end steam seals, pressure stages, last-stage long blades, and regulating stages; each basic thrust unit is further refined into several calculation parts, specifically: the pressure stage basic thrust unit includes: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the last-stage long blade basic thrust unit includes: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the regulating stage basic thrust unit includes: moving blade profile, moving blade shroud and steam seal, the impeller between the moving blade root and the radial steam seal, and the impeller between the radial steam seal and the rotor; S12. Encapsulating the thrust algorithms for each basic thrust unit into a thrust calculation module; S13. Call the basic thrust units as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model; wherein, the types and quantities of the basic thrust units in the thrust model can be freely combined; S14. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module; S15. The thrust calculation module calls the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model, and calculates the total thrust of each basic thrust unit. Step S13 includes: Step S131, for a given specific axial-flow turbine model, calling the basic thrust unit to construct a thrust model corresponding to the specific axial-flow turbine model, and obtaining the structural parameters of each basic thrust unit in the thrust model; Step S132, given the turbine operating conditions, and then obtaining the thermodynamic data of each basic thrust unit in the thrust model through thermodynamic system thermal balance calculation; wherein, the thermodynamic data of the rotor step basic thrust unit includes the static pressure at the step; the thermodynamic data of the shaft end steam seal basic thrust unit includes... Inlet and outlet pressures; the thermodynamic data of the pressure stage basic thrust unit includes the outlet static pressure, inlet and outlet axial velocity, outlet specific volume, and stage group inlet and outlet static pressure of each row of blades; the thermodynamic data of the last stage long blade basic thrust unit includes the static pressure at the blade tip, blade body, and blade root on the inlet side of the moving blade, the static pressure at the outlet side of the moving blade, the axial velocity at the inlet of the moving blade, the specific volume at the inlet and outlet of the moving blade, and the static pressure before the stationary blade steam seal; the thermodynamic data of the regulating stage basic thrust unit includes the static pressure at the outlet blade tip, blade body, and blade root of each opened nozzle group, the partial steam inlet degree corresponding to each nozzle group, and the static pressure after the moving blade corresponding to each nozzle group.

2. The method for calculating the axial thrust of an axial-flow steam turbine as described in claim 1, characterized in that, In step S13, for the thrust model, it is also necessary to obtain the steam flow direction, the mark of the balance piston, and the mark of the cylinder information in the thrust model.

3. The method for calculating the axial thrust of an axial-flow steam turbine as described in claim 1, characterized in that, The thrust calculation module encapsulates thrust algorithms for various basic thrust units, including two fundamental algorithms: thrust caused by pressure difference on both sides of a component and thrust caused by difference in the diameter of the force-bearing surface. The thrust calculation module also employs the following refined algorithms: for the shaft end steam seal basic thrust unit, different steam seal types correspond to different algorithms; for the moving blade profile in the pressure stage basic thrust unit, the influence of airflow force acting on the moving blade is considered; for the moving blade shroud and steam seal in the pressure stage basic thrust unit, different types of shrouds use... Different algorithms are used to calculate the equivalent shroud height. For the last-stage long blade basic thrust unit, the thrust is calculated in segments, divided into three segments: shroud, blade profile, and blade root. Each segment uses a different static pressure value to calculate the thrust. For the regulating stage basic thrust unit, different pressure point values ​​are used depending on whether the actual structure has a root radial steam seal. Based on the distribution of nozzle outlet static pressure along the blade height, different nozzle outlet pressure points are used to calculate the thrust at different locations. Furthermore, depending on whether the regulating stage wheel disc has a balance hole, different values ​​are used for the inlet pressure of the radial steam seal to the wheel disc section between the rotor.

4. The method for calculating the axial thrust of an axial-flow steam turbine as described in claim 1, characterized in that, The axial thrust calculation method further includes: setting the pressure value of all thermodynamic data in S13 to a first set value, and checking whether the total thrust obtained in S15 is 0, so as to verify whether the structural parameters of the thrust model are continuous.

5. A method for evaluating the diameter of the balance piston in an axial-flow steam turbine, characterized in that, The process includes the following steps: S21, classifying all axial thrust-generating components of the axial-flow turbine into several independent basic thrust units, namely: rotor steps, shaft end steam seals, pressure stages, last-stage long blades, and regulating stages; each basic thrust unit is further refined into several calculation parts, specifically: the pressure stage basic thrust unit includes: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the last-stage long blade basic thrust unit includes: moving blade profile, moving blade root, moving blade shroud and steam seal, and stationary blade steam seal; the regulating stage basic thrust unit includes: moving blade profile, moving blade shroud and steam seal, a wheel between the moving blade root and the radial steam seal, and a wheel between the radial steam seal and the rotor; S22, encapsulating the thrust algorithms for each basic thrust unit into a thrust calculation module; S23. Call the basic thrust unit as needed to construct a thrust model, and obtain the structural parameters and thermodynamic data of each basic thrust unit in the thrust model; S24. Input the structural parameters and thermodynamic data of each basic thrust unit in the thrust model into the thrust calculation module; Among the structural parameters of each basic thrust unit in the thrust model, the diameter of the balance piston is set as a guide value to prompt the thrust calculation module to calculate the diameter value of the balance piston. S25. The thrust calculation module calculates the thrust of each basic thrust unit in the thrust model by calling the corresponding thrust algorithm according to the structural parameters and thermodynamic data of each basic thrust unit, and then calculates the balance piston diameter value when the total thrust is the second set value. Step S23 includes: For a given specific axial-flow turbine model, the basic thrust units are invoked to construct a thrust model corresponding to that specific axial-flow turbine model, and the structural parameters of each basic thrust unit in the thrust model are obtained. Given the turbine operating conditions, thermal data of each basic thrust unit in the thrust model are obtained through thermal balance calculations of the thermodynamic system. The thermal data of the rotor step basic thrust unit includes the static pressure at the step; the thermal data of the shaft end steam seal basic thrust unit includes the inlet and outlet pressures; the pressure stage... The thermodynamic data of the basic thrust unit includes the outlet static pressure, inlet and outlet axial velocity, outlet specific volume, and stage inlet and outlet static pressure of each row of blades; the thermodynamic data of the last stage long blade basic thrust unit includes the static pressure at the blade tip, blade body, and blade root on the inlet side of the moving blade, the static pressure at the outlet side of the moving blade, the axial velocity at the inlet of the moving blade, the specific volume at the inlet and outlet of the moving blade, and the static pressure before the stationary blade steam seal; the thermodynamic data of the regulating stage basic thrust unit includes the static pressure at the outlet blade tip, blade body, and blade root of each opened nozzle group, the partial steam inlet degree corresponding to each nozzle group, and the static pressure behind the moving blade corresponding to each nozzle group.

6. The method for evaluating the diameter of the balance piston in an axial-flow steam turbine as described in claim 5, characterized in that, It also includes the following steps: For multiple test conditions, repeat steps S21 to S25 respectively to calculate the balance piston diameter value under multiple test conditions, and then determine the final balance piston diameter design reference value according to a certain mechanism.

7. The method for evaluating the diameter of the balance piston in an axial-flow steam turbine as described in claim 6, characterized in that, The mechanism is as follows: calculate the average or median value of the balance piston diameter under various test conditions as the design reference value for the balance piston diameter.

8. A thrust calculation system for implementing the axial thrust calculation method for an axial-flow steam turbine as described in any one of claims 1-4, and for implementing the evaluation method for the balance piston diameter of an axial-flow steam turbine as described in any one of claims 5-7, characterized in that, The thrust calculation system includes a model generation module and a thrust calculation module. The model generation module includes all basic thrust units, which can be combined as needed to construct a thrust model. The thrust calculation module has built-in thrust algorithms for all the basic thrust units. The thrust calculation module can calculate the thrust of each basic thrust unit in the thrust model, as well as the total thrust of the thrust model.

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