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

Abstract

The invention discloses a thrust calculation method, a balance piston diameter evaluation method and a thrust calculation system. The thrust calculation method comprises the steps that S11, all parts, generating axial thrust, on an axial flow turbine are classified into several independent basic thrust units; s12, respectively packaging the thrust algorithms of various basic thrust units into a thrust calculation module; s13, calling the basic thrust units as required, constructing a thrust model, and acquiring structural parameters and thermal data of each basic thrust unit in the thrust model; s14, inputting structural parameters and thermal data of each basic thrust unit in the thrust model into a thrust calculation module; s15, a thrust calculation module calculates the thrust of each basic thrust unit in the thrust model and the sum of the thrust; according to the method, the axial thrust of any axial flow turbine can be accurately calculated, the method is suitable for various types of turbines, and a data basis is provided for formulating a reasonable balance piston size and selecting a proper thrust bearing.

Description

Technical Field

[0001] The present invention relates to the field of axial flow steam turbines, and in particular to a thrust calculation method, a balance piston diameter evaluation method, and a thrust calculation system. Background Art

[0002] During operation, an axial-flow steam turbine expands and produces work as it flows from the high-pressure end to the low-pressure end. This pressure differential between the two protruding rotor components generates axial thrust from the high-pressure end toward the low-pressure end, causing axial displacement of the turbine. For multi-stage steam turbines, this axial thrust, the sum of the axial thrusts from each stage, can be considerable and poses a crucial challenge for the safe operation of the turbine unit. Therefore, accurate calculation and analysis of turbine axial thrust is crucial to developing appropriate balancing methods and selecting suitable thrust bearings.

[0003] Currently, when calculating the axial thrust of a steam turbine, the commonly used method is to manually input the various structural and thermal data of the steam turbine one by one, and then calculate the thrust based on the corresponding thrust calculation formula. However, in actual situations, due to the multiple operating conditions, the total thrust needs to be calculated for each operating condition. For multiple groups of steam turbines, the thermal data of each row of blades needs to be input one by one before the thrust is calculated. Moreover, due to the different models of different steam turbines, the specific calculation process when calculating the total thrust of different steam turbines is not exactly the same. Therefore, when calculating the axial thrust, inputting the structural and thermal data of the steam turbine one by one is a repetitive task with a large amount of work, tedious work, a high probability of error, and difficulty in proofreading and auditing. In addition, the current steam turbine thrust calculation algorithm is not sophisticated enough and has low accuracy.

[0004] Therefore, it is very necessary to propose a thrust calculation method that is simple, easy to operate and applicable to different types of steam turbines. Summary of the Invention

[0005] The purpose of the present invention is to propose a universal method for calculating the axial thrust of an axial-flow steam turbine, so as to achieve accurate calculation of the axial thrust, help technicians discover the law of thrust variation of the unit, and ensure that the thrust under the worst operating point is within the allowable range; facilitate technicians to design a balanced thrust solution and the size of the balanced piston; and assist relevant personnel in verifying the feasibility of the thrust bearing used in the unit.

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

[0007] S11. Classify all parts of an axial-flow steam turbine that can generate axial thrust into several independent basic thrust units;

[0008] S12. Encapsulate the thrust algorithms of various basic thrust units into thrust calculation modules respectively;

[0009] S13. Calling the basic thrust units as needed, constructing a thrust model, and obtaining structural parameters and thermal 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, inputting the structural parameters and thermal 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 steam turbine that can generate axial thrust are summarized and 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 broken down into several calculation parts, specifically:

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

[0015] The last stage long blade thrust unit includes: a moving blade profile, a moving blade root, a moving blade shroud and steam seal, and a stationary blade steam seal;

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

[0017] Optionally, step S13 includes:

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

[0019] S132. Given a steam turbine operating condition, thermal data of each basic thrust unit in the thrust model is obtained through thermal balance calculation of the thermal system;

[0020] Wherein, the thermal data of the rotor step base thrust unit includes the static pressure at the step;

[0021] The thermal data of the shaft end steam seal basic thrust unit include inlet and outlet pressures;

[0022] The thermal data of the basic thrust unit of the pressure stage include the outlet static pressure, inlet and outlet axial velocity, outlet specific volume, and inlet and outlet static pressure of each row of blades;

[0023] The thermal data of the last stage long blade basic thrust unit include the static pressure of the blade tip, blade body, and blade root on the rotor blade inlet side, the static pressure on the rotor blade outlet side, the rotor blade inlet axial velocity, the rotor blade inlet and outlet specific volumes, and the static pressure before the stator steam seal;

[0024] The thermal data of the regulating stage basic thrust unit include the static pressure of the outlet blade tip, blade body, and blade root of each opened nozzle group, the partial steam inlet 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 of various basic thrust units, including two most basic thrust algorithms: thrust caused by pressure difference on both sides of the part and thrust caused by difference in diameter of the force-bearing surface;

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

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

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

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

[0031] For the basic thrust unit of the last stage long blade, the thrust is calculated by segmentation, which is divided into three sections: the shroud, the blade profile, and the blade root. Different static pressure values are used for each section to calculate the thrust.

[0032] For the basic thrust unit of the regulating stage, different pressure point values are adopted according to whether the actual structure has a root radial steam seal. Different nozzle outlet pressure points are used to calculate the thrust of different parts according to the distribution of the static pressure at the nozzle outlet along the blade height. Different values of the inlet pressure of the wheel part between the radial steam seal and the rotor are adopted according to whether there are balancing holes in the regulating stage wheel.

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

[0034] Another aspect of the present invention provides a method for evaluating the diameter of a balancing piston of an axial flow steam turbine, comprising the following steps:

[0035] S21. Classify all parts of an axial-flow steam turbine that generate axial thrust into several independent basic thrust units;

[0036] S22. Encapsulate the thrust algorithms of various basic thrust units into thrust calculation modules respectively;

[0037] S23. Calling the basic thrust unit as needed, building a thrust model, and obtaining structural parameters and thermal data of each basic thrust unit in the thrust model;

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

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

[0040] Optionally, the method for evaluating the balancing piston diameter further includes: repeating steps S21 to S25 for multiple assessment working conditions, calculating the balancing piston diameter values under the multiple assessment working conditions, and then determining the final balancing piston diameter design reference value according to a certain mechanism.

[0041] Optionally, the mechanism is: calculating the average or median of the balance piston diameter values under multiple assessment conditions as the design reference value of the balance piston diameter.

[0042] The present invention also proposes a thrust calculation system for implementing the above-mentioned thrust calculation method and the above-mentioned method for evaluating the diameter of a balancing piston. The thrust calculation system includes: a model generation module and a thrust calculation module; the model generation module includes all basic thrust units, and the basic thrust units can be combined as needed to construct a thrust model; the thrust calculation module has a built-in thrust algorithm for all the basic thrust units, and 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.

[0043] The present invention also proposes a computer-readable storage medium having a computer program stored thereon. When the computer program is run, the electronic device where the computer-readable storage medium is located is controlled 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 scheme 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, and can help technicians discover the thrust variation pattern of the unit and ensure that the thrust under the worst operating condition is within the allowable range; it can also help check the continuity of rotor structure data.

[0046] The balance piston diameter evaluation method disclosed in this solution can design and evaluate the balance piston diameter based on accurate axial thrust calculation results, which helps to speed up the design process and improve the operating stability of the axial flow steam turbine. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0048] Figure 2 Schematic diagram of the blade structure of a steam turbine;

[0049] Figure 3 The present invention is a flow chart of a method for evaluating the diameter of a balancing piston of an axial flow steam turbine.

[0050] Reference numerals:

[0051] 1 is the blade tip on the steam inlet side;

[0052] 2 is the blade on the steam inlet side;

[0053] 3 is the blade root on the steam inlet side;

[0054] 4 is the blade tip on the steam outlet side;

[0055] 5 is the blade on the steam outlet side;

[0056] 6 is the blade root on the steam outlet side;

[0057] 7 is a leaf. DETAILED DESCRIPTION

[0058] The technical solutions, structural features, achieved objectives and effects of the embodiments 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 drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

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

[0061] This embodiment discloses a method for calculating the axial thrust of an axial flow steam turbine, which is suitable for calculating the axial thrust of an axial flow steam turbine. 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. Encapsulating the thrust algorithms of various basic thrust units and the thrust calculation part into thrust calculation modules respectively;

[0064] S13. Calling the basic thrust units as needed, constructing a thrust model, and obtaining structural parameters and thermal 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, inputting the structural parameters and thermal 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, all parts of the axial-flow steam turbine capable of generating axial thrust are summarized and classified into several independent basic thrust units, namely: rotor step, shaft end steam seal, pressure stage, last stage long blade, and regulating stage. Furthermore, each basic thrust unit can be further refined into several calculation parts. Specifically, the pressure stage can be further refined into multiple thrust calculation parts, namely: rotor blade profile, rotor blade root, rotor blade shroud and steam seal, and stator blade steam seal; the last stage long blade can be further refined into multiple thrust calculation parts, namely: rotor blade profile, rotor blade root, rotor blade shroud and steam seal, and stator blade steam seal; and the regulating stage can be further refined into multiple thrust calculation parts, namely: rotor blade profile, rotor blade shroud and steam seal, disc between rotor blade root and radial steam seal, and disc between radial steam seal and rotor. Table 1 below intuitively illustrates the thrust calculation components of each basic thrust unit.

[0068] Table 1 Disassembly of thrust unit

[0069]

[0070]

[0071] In step S13, the various basic thrust units from S11 are called upon as needed to construct a thrust model. This means that in actual use, the types and quantities of the basic thrust units can be flexibly combined and freely arranged according to actual needs to construct the desired thrust model. The present invention categorizes all thrust-generating components of an axial-flow steam turbine into a variety of basic thrust units, facilitating their combination to construct a thrust model as needed. This makes the present invention's method applicable to a variety of axial-flow steam turbine models, thereby increasing the scope of application and flexibility of the present invention.

[0072] In addition, since the thrust of each basic thrust unit needs to be calculated based on the pressure value and the force-bearing area, step S13 also includes: acquiring structural data and thermal data of each basic thrust unit in the thrust model.

[0073] Specifically, step S13 further includes the following steps:

[0074] Step S131: For a given specific axial-flow steam turbine model, call the basic thrust unit, construct a thrust model corresponding to the specific axial-flow steam turbine model, and obtain structural parameters of each basic thrust unit in the thrust model;

[0075] Step S132: Given the steam turbine operating conditions, thermal data of each basic thrust unit in the thrust model is obtained through thermal balance calculation of the thermal system.

[0076] The pressure values for each thrust unit are derived from thermal data obtained from the thermal system's heat balance calculation. This calculation comprehensively analyzes and calculates the entire thermal cycle of the steam turbine. Based on given turbine operating conditions, such as load, initial steam parameters (pressure and temperature), and exhaust parameters, it determines the energy distribution and conversion within the system. This ensures that the entire thermal system adheres to the law of conservation of energy during design and operation, achieving efficient and stable operation. Table 2 below shows the thermal data required for each thrust unit.

[0077] Table 2 Thermal parameters required for thrust calculation

[0078]

[0079] Among them, the thrust composition of the pressure stage is the same as that of the long blade. In the above-mentioned last-stage long blade thrust unit, the static pressure of the blade tip, blade body, and blade root on the inlet side of the moving blade is distinguished because: the long blade is longer, and the pressure distribution of the blade tip, blade body, and blade root has certain differences. Therefore, it is necessary to use corresponding pressures for different parts to calculate the thrust. Figure 2 For example, Figure 2 Figure 7 is a schematic diagram of the structure of blade 7. When it is a pressure level, the static pressure at the mid-diameter inlet of the moving blade is taken at the steam inlet side tip 1, the steam inlet side blade body 2 and the steam inlet side blade root 3. For long blades, the static pressure at the tip, mid-diameter and root of the moving blade are taken respectively. Because the static pressure at the moving blade outlet is more evenly distributed along the blade height, the static pressure at the steam outlet side tip 4, the steam outlet side blade body 5 and the steam outlet side blade root 6 is uniformly taken as the mid-diameter outlet static pressure. Then, the root reaction and the top reaction are calculated respectively according to the static pressure reaction, and then the static pressure at the root and tip of the moving blade is calculated. The following is the static pressure algorithm at the tip and root of the moving blade inlet side:

[0080] RP=(SPIRB mean -SPORB mean ) / (SPISB mean -SPORB mean )

[0081] Rk=1-(1-RP)×EMDTSB / (EMDTSB-EHTMB)

[0082] Rn=1-(1-RP)×EMDTSB / (EMDTSB+EHTMB)

[0083] SPIRB root =(SPISB mean -SPORB mean )×Rk+SPORB mean

[0084] SPIRB top =(SPISB mean -SPORB mean )×Rn+SPORB mean

[0085] Among them, RP represents the static pressure reaction, SPIRB mean Indicates the static pressure at the inlet of the moving blade at the mid-diameter, SPORB mean Indicates the static pressure at the outlet of the moving blade at the mid-diameter, SPISB mean represents the static pressure at the mid-diameter of the stator blade, Rk represents the root reaction, EMDTSB represents the effective mid-diameter of the stator blade throat, EHTMB represents the effective height of the moving blade throat, Rn represents the top reaction, SPIRB root Indicates the static pressure at the root of the moving blade, SPIRB top Indicates the inlet static pressure at the blade tip.

[0086] 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.

[0087] Table 3 Structural parameters required for thrust calculation

[0088]

[0089]

[0090] Furthermore, in step S13, for the thrust model, in addition to the structural parameters 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. Among them, the steam flow direction is downstream or reverse flow, which is used to determine the positive or negative thrust, for example, stipulating that the right is a positive value. The marking of the cylinder information is equivalent to grouping the basic thrust units. The basic thrust units belonging to the same cylinder body are marked with the same group name, such as Casing1. Subsequently, in step S15, the thrust sum of the basic thrust units included in each cylinder body can also be calculated; the marking of the balancing piston means 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). By setting the marking of the balancing piston, it is convenient to evaluate the diameter of the balancing piston in the future.

[0091] The thrust calculation module encapsulates thrust algorithms of various basic thrust units, including two most basic thrust algorithms, namely the thrust caused by the pressure difference on both sides of the part and the thrust caused by the difference in the diameter of the force-bearing surface. The specific calculation methods are:

[0092] For the thrust caused by the pressure difference on both sides of a certain part: TCPD=LSP×LSFA-RSP×RSFA, LSFA=π / 4×(LSOD 2 -LSID 2 ), RSFA=π / 4×(RSOD 2 -RSID 2 ), where TCPD represents the thrust caused by the pressure difference between the left and right sides of the part, LSP represents the left static pressure, LSFA represents the left force area, RSP represents the right static pressure, RSFA represents the right force area, LSOD represents the left outer diameter, LSID represents the left inner diameter, RSOD represents the right outer diameter, and RSID represents the right inner diameter;

[0093] For the thrust caused by the difference in diameter of a certain load-bearing surface: ToS=SP×AFBA,AFBA=π / 4×(OD 2 -ID 2 ), where ToS represents the thrust due to the difference in diameter of the load-bearing surface, SP represents the static pressure at the load-bearing surface, AFBA represents the annular load-bearing area, OD represents the outer diameter of the load-bearing surface, and ID represents the inner diameter of the load-bearing surface.

[0094] The code shown below encapsulates the above two basic algorithms and stores them in the thrust calculation module for use when calculating the thrust of each basic thrust unit.

[0095]

[0096] 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 the sum of them as the axial thrust of the axial flow steam turbine. Among them, different basic thrust units have different thrust calculation methods, and the thrust algorithm of the thrust calculation module also adopts the following refined algorithms: for the shaft end steam seal thrust unit, different steam seal types correspond to different algorithms; for the moving blade blade shape in the pressure stage 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 thrust unit, different algorithms need to be used to calculate the equivalent shroud height for different types of shrouds (the moving blade shrouds in other thrust units are the same); for the last stage long blade thrust unit, since the long blades are relatively long, the equivalent shroud height needs to be calculated using different algorithms. The pressures at the blade tip, blade body, and blade root vary significantly due to the blade length. Considering the pressure distribution along the blade rise, thrust calculation is performed segmentally: the blade is divided into three sections: the shroud, the blade profile, and the blade root. Different static pressure values are used for each section to calculate thrust. For the regulating stage thrust unit, different pressure point values are used based on the presence or absence of a root radial steam seal in the actual structure. Furthermore, different nozzle outlet pressure points are used to calculate thrust at different locations based on the distribution of static pressure at the nozzle outlet along the blade height. Furthermore, different values are used for the inlet pressure of the disc portion between the radial steam seal and the rotor, depending on whether or not there are balancing holes in the regulating stage disc. Through these refined calculations, the actual structure of the steam turbine and the flow characteristics of the working fluid are fully considered, resulting in more accurate calculated axial thrust.

[0097] Among them, in the pressure stage and the last stage long blades, when calculating the thrust acting on the moving 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 of axial momentum when the steam passes through the moving blade is also considered. a (i.e. the thrust caused by airflow force), the calculation process is:

[0098]

[0099] Among them, G is the mass flow rate flowing through the stage, υ 1、 υ2 is the specific volume of steam entering the moving blade and the specific volume of steam flowing out of the moving blade, c1 and c2 are the relative speed of steam entering the moving blade and the relative speed of steam flowing out of the moving blade, α1 and α2 are the relative steam flow angle of the steam inlet and exhaust, respectively. ax1 、c ax2 are the axial velocity of steam entering the moving blade and the axial velocity of steam flowing out of the moving blade, A a1 、A a2 They are the force bearing area on the steam inlet side and the force bearing area on the steam outlet side, p1 and p2 are the static pressure on the steam inlet side and the static pressure on the steam outlet side respectively.

[0100] The thrust calculation formula for each component is the product of the component's load-bearing area and the pressure difference across the front and rear of the component. The load-bearing area can be determined based on structural parameters, and the pressure difference can be determined based on thermal data. Both are commonly used calculation methods. The focus of this solution is not the most basic mathematical model mentioned above, but rather the unitization of all parts of the turbine main shaft that generate axial thrust into several independent thrust units. These thrust units can be freely arranged, and the units can be flexibly combined to construct a thrust model based on project conditions. This approach is applicable to a variety of machine models, so the specific calculation of the thrust of each basic thrust unit will not be described in detail here.

[0101] Furthermore, the axial thrust calculation method of the axial flow steam turbine of this embodiment can also be used to verify whether the structural parameters of the thrust model are continuous. Specifically: the pressure values of all thermal data in S13 are set to the first set value, and the total thrust obtained in S14 is checked to see if it is 0. The size 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 staff of the rationality of the structural dimensions. Among them, for some thrust calculation formulas, such as the above thrust F a In the calculation formula, υ1 / c ax1 and υ2 / c ax2 Set to 1, that is, the steam specific volume and steam axial velocity are set to 1.

[0102] The above-mentioned axial thrust calculation method for an axial-flow steam turbine covers all necessary basic thrust unit types, and the basic thrust units can be freely arranged. The basic thrust units can be flexibly combined to construct a thrust model according to project conditions. Therefore, the present invention is not limited by the machine model and is applicable to the thrust analysis of any axial-flow steam turbine unit, with good versatility.

[0103] In another embodiment, a method for evaluating the diameter of a balancing piston is also disclosed, such as Figure 3 As shown, the following steps are included:

[0104] S21. Classify all parts of an axial-flow steam turbine that generate axial thrust into several independent basic thrust units;

[0105] S22. Encapsulate the thrust algorithms of various basic thrust units into thrust calculation modules respectively;

[0106] S23. Calling the basic thrust unit as needed, building a thrust model, and obtaining structural parameters and thermal data of each basic thrust unit in the thrust model;

[0107] S24, inputting the structural parameters and thermal data of each basic thrust unit in the thrust model into the thrust calculation module;

[0108] Among the structural parameters of each basic thrust unit of the thrust model, the diameter of the balancing piston is set as a guide value to prompt the thrust calculation module to calculate the diameter value of the balancing piston. The specific value of the guide value is not specified and can be set according to actual conditions. In this embodiment, the guide value is set to -999.

[0109] S25. The thrust calculation module uses the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model based on the structural parameters and thermal data of each basic thrust unit. The module then calculates the balancing piston diameter when the total thrust is equal to a second set value. This balancing piston diameter is then used as a reference to design the balancing piston for improved stability. The second set value can be selected based on actual conditions. In this embodiment, the second set value is 0.

[0110] Since the balancing piston includes two left and right bosses (rotor step units) and a steam seal in the middle (shaft end steam seal unit), the diameter of the balancing piston is set as a guide value, that is, the rotor diameter of the shaft end steam seal unit, the right side diameter of the left boss, and the left side diameter of the right boss are all set as guide values.

[0111] Except for the difference in the diameter of the balancing piston in S24, the above steps S21 to S24 are identical to the above steps S11 to S14 of the axial thrust calculation method.

[0112] Furthermore, the present method can also comprehensively consider different operating conditions, repeatedly calculating the balancing piston diameter values under different assessment conditions, and then executing step S26 to determine the final balancing 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 balancing piston diameter values under different assessment conditions as a reference value for balancing piston diameter design.

[0113] Finally, the present invention also discloses a thrust calculation system for implementing the above-mentioned axial thrust calculation method and balance piston diameter evaluation method. The thrust calculation system includes: a model generation module and a thrust calculation module; the model generation module includes all basic thrust units, and the basic thrust units can be combined as needed to construct a thrust model; the thrust calculation module has a built-in thrust algorithm for all the basic thrust units, and the thrust calculation module can calculate the thrust of each basic thrust unit in the thrust model, as well as calculate the total thrust of the thrust model.

[0114] In actual use, when implementing the axial thrust calculation method, the basic thrust units are freely combined in the model generation module as needed to generate a turbine thrust model that meets the requirements. The turbine thrust model is then input into the thrust calculation module. The structural parameters and thermal parameters of each basic thrust unit in the thrust model are then input into the thrust calculation module. The thrust calculation module calculates the thrust of each basic thrust unit separately and then calculates the total thrust of the entire turbine thrust model. When implementing the balance piston diameter evaluation method, the basic thrust units are freely combined in the model generation module as needed to generate a turbine thrust model that meets the requirements. The turbine thrust model is then input into the thrust calculation module. The structural parameters and thermal parameters of each basic thrust unit in the thrust model are then input into the thrust calculation module. The diameter of the balance piston is set as a guide value, and the thrust calculation module calculates the diameter value of the balance piston when the total thrust is a second set value.

[0115] Based on the above-mentioned axial thrust calculation method and balance piston diameter evaluation method, an embodiment of the present invention also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is run, it controls the electronic device where the readable storage medium is located to execute the above-mentioned axial thrust calculation method or balance piston diameter evaluation method.

[0116] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. 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 following steps are involved: S11. Classify all parts of an axial-flow steam turbine that can generate axial thrust into several independent basic thrust units; S12. Encapsulate the thrust algorithms of various basic thrust units into thrust calculation modules respectively; S13. Calling the basic thrust units as needed, constructing a thrust model, and obtaining structural parameters and thermal 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, inputting the structural parameters and thermal 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.

2. The method for calculating the axial thrust of an axial flow steam turbine according to claim 1, wherein: In step S11, all parts of the axial flow steam turbine that can generate axial thrust are classified into several independent basic thrust units, namely: rotor step, shaft end steam seal, pressure stage, last stage long blade, and regulating stage; Each basic thrust unit is further broken down into several calculation parts, specifically: The pressure-stage thrust unit includes: a moving blade profile, a moving blade root, a moving blade shroud and steam seal, and a stationary blade steam seal; The last stage long blade thrust unit includes: a moving blade profile, a moving blade root, a moving blade shroud and steam seal, and a stationary blade steam seal; The regulating stage thrust unit comprises: a moving blade profile, a moving blade shroud and a steam seal, a wheel disc between the moving blade root and the radial steam seal, and a wheel disc between the radial steam seal and the rotor.

3. The method for calculating the axial thrust of an axial flow steam turbine according to claim 2, wherein: Step S13 includes: Step S131: For a given specific axial-flow steam turbine model, call the basic thrust unit, construct a thrust model corresponding to the specific axial-flow steam turbine model, and obtain structural parameters of each basic thrust unit in the thrust model; S132. Given a steam turbine operating condition, thermal data of each basic thrust unit in the thrust model is obtained through thermal balance calculation of the thermal system; Wherein, the thermal data of the rotor step base thrust unit includes the static pressure at the step; The thermal data of the shaft end steam seal basic thrust unit include inlet and outlet pressures; The thermal data of the basic thrust unit of the pressure stage include the outlet static pressure, inlet and outlet axial velocity, outlet specific volume, and inlet and outlet static pressure of each row of blades; The thermal data of the last stage long blade basic thrust unit include the static pressure of the blade tip, blade body, and blade root on the rotor blade inlet side, the static pressure on the rotor blade outlet side, the rotor blade inlet axial velocity, the rotor blade inlet and outlet specific volumes, and the static pressure before the stator steam seal; The thermal data of the regulating stage basic thrust unit include the static pressure of the outlet blade tip, blade body, and blade root of each opened nozzle group, the partial steam inlet corresponding to each nozzle group, and the static pressure behind the moving blade corresponding to each nozzle group.

4. The method for calculating the axial thrust of an axial flow steam turbine according to claim 1, wherein: 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.

5. The method for calculating the axial thrust of an axial flow steam turbine according to claim 3, wherein: The thrust calculation module encapsulates thrust algorithms of various basic thrust units, including two most basic thrust algorithms: thrust caused by pressure difference on both sides of the part and thrust caused by difference in diameter of the force-bearing surface; The thrust calculation module also uses the following refined algorithm: For the shaft end steam seal basic thrust unit, different steam seal types correspond to different algorithms; For the blade profile of the basic thrust unit of the pressure level, the influence of the airflow force acting on the blade is considered; For the moving blade shrouds and steam seals in the basic thrust unit of the pressure stage, different algorithms are used to calculate the equivalent shroud height for different types of shrouds; For the basic thrust unit of the last stage long blade, the thrust is calculated by segmentation, which is divided into three sections: the shroud, the blade profile, and the blade root. Different static pressure values are used for each section to calculate the thrust. For the basic thrust unit of the regulating stage, different pressure point values are adopted according to whether the actual structure has a root radial steam seal. Different nozzle outlet pressure points are used to calculate the thrust of different parts according to the distribution of the static pressure at the nozzle outlet along the blade height. Different values of the inlet pressure of the wheel part between the radial steam seal and the rotor are adopted according to whether there are balancing holes in the regulating stage wheel.

6. The method for calculating the axial thrust of an axial flow steam turbine according to claim 1, wherein: The axial thrust calculation method further includes: setting the pressure values of all thermal data in S13 to a first set value, and checking whether the thrust sum obtained in S15 is 0 to verify whether the structural parameters of the thrust model are continuous.

7. A method for evaluating the balance piston diameter of an axial flow steam turbine, characterized in that: The following steps are involved: S21. Classify all parts of an axial-flow steam turbine that generate axial thrust into several independent basic thrust units; S22. Encapsulate the thrust algorithms of various basic thrust units into thrust calculation modules respectively; S23. Calling the basic thrust unit as needed, building a thrust model, and obtaining structural parameters and thermal data of each basic thrust unit in the thrust model; S24, inputting the structural parameters and thermal data of each basic thrust unit in the thrust model into the thrust calculation module; Among the structural parameters of each basic thrust unit of the thrust model, the diameter of the balancing piston is set as a guide value to prompt the thrust calculation module to calculate the diameter value of the balancing piston; S25. The thrust calculation module calls the corresponding thrust algorithm to calculate the thrust of each basic thrust unit in the thrust model according to the structural parameters and thermal data of each basic thrust unit, and then calculates the balance piston diameter value when the total thrust is a second set value.

8. The method for estimating the balance piston diameter of an axial flow steam turbine according to claim 7, wherein: The method further includes the following steps: for a plurality of assessment working conditions, repeating steps S21 to S25 respectively, calculating the balance piston diameter values under the plurality of assessment working conditions, and then determining the final balance piston diameter design reference value according to a certain mechanism.

9. The method for estimating the balance piston diameter of an axial flow steam turbine according to claim 8, wherein: The mechanism is: calculating the average value or median of the balance piston diameter values under multiple assessment working conditions as the design reference value of the balance piston diameter.

10. A thrust calculation system for implementing the axial thrust calculation method for an axial flow steam turbine according to any one of claims 1 to 6, and for implementing the method for estimating the balance piston diameter for an axial flow steam turbine according to any one of claims 7 to 9, 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 and can combine the basic thrust units as needed to construct a thrust model; the thrust calculation module has a built-in thrust algorithm for all the basic thrust units, and 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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