A method for determining the strength of steam turbine transverse anchor plates

Abstract

A method for determining the strength of a steam turbine transverse anchor plate is disclosed. This method addresses the issue of the danger of uneven frictional forces acting on the transverse anchor plate, a lateral positioning structure between the turbine bearing housing and the base frame, during expansion and contraction of the turbine, as the turbine expands axially from the cylinder dead center via a push-pull structure. The method comprises the following steps: calculating the transverse load P on the anchor plate, where the vertical load includes the component gravity load, which refers to the load in the vertical direction on the anchored stationary component; and calculating the composite stress of the anchor plate: the load distribution between the anchor plate and the connector is triangular, with a point load at 1 / 3 of the contact length of the active surface, and the point at 13h being the point of application of load P. The stresses at points 0, 1, and 2 must all be less than the yield strength of the anchor plate to determine that the anchor plate meets the requirements. This invention pertains to the field of steam turbines.

Description

Technical Field

[0001] The invention relates to a method for determining the strength of an anchor plate, in particular to a method for calculating the strength of a transverse anchor plate of a steam turbine. The invention belongs to the field of steam turbines. Background Art

[0002] Steam turbine transverse anchor plates, serving as the locating structure connecting the bearing housing to the base frame, are an essential component of a steam turbine unit. Typically, the stator components of a steam turbine generator unit experience high operating temperatures, causing axial expansion relative to the base plate. This expansion must be accommodated by flexibility or inter-component sliding. Without the restraint of transverse anchor plates, load cycling can cause minor lateral displacement of the unit. This can result in binding of the turbine, generator, or exciter brackets during expansion or contraction. Over multiple load cycles, this effect can accumulate. If uncontrolled, misalignment can occur, leading to unsafe and stable unit operation. However, there is no systematic method for calculating the strength of steam turbine transverse anchor plates. With the continuous innovation of steam turbine design, cost reduction and efficiency improvement are becoming increasingly important, and assessing the strength of transverse anchor plates has become a priority. Summary of the Invention

[0003] In order to solve the problem that the transverse anchor plate, as a transverse positioning structure between the turbine bearing box and the base frame, expands axially from the dead point of the cylinder through the push-pull structure, is subjected to unbalanced friction during the expansion and contraction of the turbine, and thus a method for determining the strength of the transverse anchor plate of the turbine is needed.

[0004] The present invention solves the above technical problems through the following solutions:

[0005] A method for calculating the strength of steam turbine transverse anchor plates.

[0006] The method is implemented according to the following steps:

[0007] Calculate the anchor plate lateral load P,

[0008] P=G×Δu

[0009] Where: G is the total vertical load in one quadrant of the anchored component;

[0010] Δu is the difference in friction coefficient from one side to the other;

[0011] Vertical loads include component gravity loads, which refer to the loads in the vertical direction on the anchored stationary components.

[0012] According to Eder: Component gravity load

[0013] Calculation of composite stress of anchor plate:

[0014] Composite stress at point 0

[0015]

[0016] Composite stress at point 1

[0017]

[0018] Composite stress at point 2

[0019]

[0020] Where Z x The modulus of the section is equal to W(i) 2 f / 6, Z z The modulus of the section is equal to f 2 W(i) / 6,

[0021] f is the thickness of the anchor plate;

[0022] W(i) is the width of the anchor plate at the inspected section, and the section where the width changes is the dangerous section;

[0023] P is the lateral load of the anchor plate;

[0024] u is the average friction coefficient between the end face of the anchor plate and the connecting piece,

[0025] uP is the friction between the anchor plate and the L-shaped gasket;

[0026] L(i) is the height between the load application point and the inspected section.

[0027] The distribution of load between the anchor plate and the connector is triangular. A point load is applied at 1 / 3 of the contact length of the action surface. The point where the load P is applied is 1 / 3h. The stress at points 0, 1, and 2 must all be less than the yield strength of the anchor plate. The anchor plate strength is qualified. Furthermore, for condensers with expansion joints, the vertical load on the low-pressure cylinder is caused by the unbalanced pressure at the expansion joint between the low-pressure cylinder and the condenser shell. Therefore, P N =(atmospheric pressure - low pressure exhaust pressure) MPa × low pressure cylinder exhaust throat flow area (mm 2 ).

[0028] Furthermore, when the anchor plate is fitted with the bearing housing and base frame, the friction surface is the interface between the support leg and the base plate, steel against steel. max =0.4;u min =0.1;Δu=0.3.

[0029] Furthermore,

[0030] When the bearing box bottom plate is connected to the base frame through anchor bolts, the vertical load of the bearing box anchor plate includes the component gravity load and the anchor bolt load. The anchor bolt load is P b ,

[0031] P b =NA b δ b

[0032] Where:

[0033] N is the total number of anchor bolts;

[0034] A b is the minimum cross-sectional area of ​​the anchor bolt;

[0035] δ b is the initial installation stress of the anchor bolts;

[0036] at this time: (Component gravity load + anchor bolt load).

[0037] Furthermore, the low-pressure cylinder bottom plate and the base frame are generally not connected by anchor bolts. The vertical load of the low-pressure cylinder anchor plate includes the component gravity load and the downward condenser load. The component gravity load refers to the load in the vertical direction on the anchored static component.

[0038] at this time: (Component gravity load + condenser load).

[0039] The most outstanding features and significant beneficial effects of the present invention are:

[0040] This invention proposes a systematic method for calculating transverse anchor plate strength, improving the theoretical basis for calculating transverse anchor plate strength, speeding up the work of unit designers, and saving costs. It provides a practical theoretical basis for future transverse anchor plate optimization and ensures smooth unit startup and operation. The invention considers the stress generated by this force at critical points on the transverse anchor plate's critical section and assesses whether these stresses are within the allowable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the arrangement of the transverse anchor plates, where M is the anchor plate.

[0042] Figure 2 Schematic diagram of the transverse anchor plate assembly.

[0043] Figure 3 Schematic diagram of the force analysis of the transverse anchor plate.

[0044] Figure 4Schematic diagram of the transverse anchor plate dimensions. In the figure, W(i) is one of W(1), W(2), or W(3), and L(i) is one of L(1), L(2), L(3), or L(4).

[0045] Figure 5 Schematic diagram of transverse anchor plate load analysis.

[0046] Figure 6 This is a diagram of the anchor bolt assembly. DETAILED DESCRIPTION

[0047] Specific implementation method 1: Combination Figures 1-6 This embodiment is described. This embodiment provides a method for determining the strength of a transverse anchor plate of a steam turbine.

[0048] The method is implemented according to the following steps:

[0049] Calculate the anchor plate lateral load P,

[0050] P=G×Δu

[0051] Where: G is the total vertical load in one quadrant of the anchored component;

[0052] Δu is the difference in friction coefficient from one side to the other;

[0053] Vertical loads include component gravity loads, which refer to the loads in the vertical direction on the anchored stationary components.

[0054] According to Eder: Component gravity load,

[0055] Calculation of composite stress of anchor plate:

[0056] Composite stress at point 0

[0057]

[0058] Composite stress at point 1

[0059]

[0060] Composite stress at point 2

[0061]

[0062] Where Z x The modulus of the section is equal to W(i) 2 f / 6, Z z The modulus of the section is equal to f 2 W(i) / 6,

[0063] f is the thickness of the anchor plate;

[0064] W(i) is the width of the anchor plate at the inspected section, and the section where the width changes is the dangerous section;

[0065] P is the lateral load of the anchor plate;

[0066] u is the average friction coefficient between the end face of the anchor plate and the connecting piece,

[0067] uP is the friction between the anchor plate and the L-shaped gasket;

[0068] L(i) is the height between the load application point and the inspected section.

[0069] The distribution of load between the anchor plate and the connector is triangular, with a point load at 1 / 3 of the contact length of the action surface, and 1 / 3h is the action point of load P. It is determined that the stress at points 0, 1, and 2 must all be less than the yield strength of the anchor plate, and the strength of the anchor plate is qualified.

[0070] Specific implementation method 2: Combination Figures 1-6 This embodiment is described. This embodiment provides a method for determining the strength of a transverse anchor plate of a steam turbine. For a condenser with an expansion joint, the vertical load on the low-pressure cylinder is caused by the unbalanced pressure in the expansion joint between the low-pressure cylinder and the condenser shell. Therefore, P N =(atmospheric pressure - low pressure exhaust pressure) MPa × low pressure cylinder exhaust throat flow area (mm 2 ). The condenser load is P N , other structural connection relationships are the same as those in the first specific implementation method.

[0071] Specific implementation method three: Combination Figures 1-6 This embodiment is described. This embodiment provides a method for determining the strength of a steam turbine transverse anchor plate. When the anchor plate is matched with the bearing box and the base frame, the friction surface is the interface between the support leg and the base plate. Steel against steel u max =0.4;u min =0.1;Δu=0.3.

[0072] The load calculation assumes the most extreme possible situation, where the maximum friction coefficient occurs on one side of the machine's axial centerline (e.g. Figure 4 The second and third quadrants), while the smallest coefficients are on the other side (such as Figure 4 The calculated anchor plate loads for the first and fourth quadrants represent the worst-case scenario and do not represent typical operating loads. The allowable stress does not include a safety factor, which is already factored in when calculating the maximum possible load. Other structural connections remain the same as in Specific Embodiment 1.

[0073] Specific implementation method four: Combination Figures 1-6 This embodiment is described. This embodiment provides a method for determining the strength of a transverse anchor plate of a steam turbine.

[0074] When the bearing box bottom plate is connected to the base frame through anchor bolts, the vertical load of the bearing box anchor plate includes the component gravity load and the anchor bolt load. The anchor bolt load is P b ,

[0075] P b =NA b δ b

[0076] Where:

[0077] N is the total number of anchor bolts;

[0078] A b is the minimum cross-sectional area of ​​the anchor bolt;

[0079] δ b is the initial installation stress of the anchor bolts;

[0080] at this time: (Component gravity load + anchor bolt load). Other structural connection relationships are the same as those in the first embodiment.

[0081] Specific implementation method five: Combination Figures 1-6 This embodiment is explained. This embodiment provides a method for determining the strength of a transverse anchor plate of a steam turbine. The low-pressure cylinder bottom plate and the base frame are generally not connected by anchor bolts. The vertical load of the low-pressure cylinder anchor plate includes the component gravity load and the downward condenser load. The component gravity load refers to the load in the vertical direction on the anchored static component.

[0082] at this time: (Component gravity load + condenser load) Other structural connection relationships are the same as those in the first embodiment.

[0083] The embodiments of the present invention disclosed above are intended only to illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A method for determining the strength of a steam turbine transverse anchor plate, characterized in that: The method is implemented according to the following steps: Calculate the anchor plate lateral load P, P=G×Δu Where: G is the total vertical load in one quadrant of the anchored component; Δu is the difference in friction coefficient from one side to the other; Vertical loads include component gravity loads, which refer to the loads in the vertical direction on the anchored stationary components. According to Eder: Component gravity load Calculation of composite stress of anchor plate: Composite stress at point 0 Composite stress at point 1 Composite stress at point 2 Where Z x The modulus of the section is equal to W(i) 2 f / 6, Z z The modulus of the section is equal to f 2 W(i) / 6, f is the thickness of the anchor plate; W(i) is the width of the anchor plate at the inspected section, and the section where the width changes is the dangerous section; P is the lateral load of the anchor plate; u is the average friction coefficient between the end face of the anchor plate and the connecting piece, uP is the friction between the anchor plate and the L-shaped gasket; L(i) is the height between the load application point and the inspected section; The distribution of load between the anchor plate and the connector is triangular, with a point load at 1 / 3 of the contact length of the action surface, and 1 / 3h is the action point of load P. It is determined that the stress at points 0, 1, and 2 must all be less than the yield strength of the anchor plate, and the strength of the anchor plate is qualified.

2. A method for determining the strength of a steam turbine transverse anchor plate according to claim 1, characterized in that: For condensers with expansion joints, the vertical load on the low-pressure cylinder is caused by the unbalanced pressure in the expansion joint between the low-pressure cylinder and the condenser shell. N =(atmospheric pressure - low pressure exhaust pressure) MPa × low pressure cylinder exhaust throat flow area mm 2 , the condenser load is P N .

3. The method for determining the strength of a steam turbine transverse anchor plate according to claim 1, wherein: When the anchor plate is fitted with the bearing housing and base frame, the friction surface is the interface between the support leg and the base plate, steel against steel. max =0.4;u min =0.1;Δu=0.

3.

4. The method for determining the strength of a steam turbine transverse anchor plate according to claim 1, wherein: When the bearing box bottom plate is connected to the base frame through anchor bolts, the vertical load of the bearing box anchor plate includes the component gravity load and the anchor bolt load. The anchor bolt load is P b , P b =NA b δ b Where: N is the total number of anchor bolts; A b is the minimum cross-sectional area of ​​the anchor bolt; δ b is the initial installation stress of the anchor bolts; at this time: (Component gravity load + anchor bolt load).

5. The method for determining the strength of a steam turbine transverse anchor plate according to claim 1, wherein: The low-pressure cylinder bottom plate and the base frame are generally not connected by anchor bolts. The vertical load of the low-pressure cylinder anchor plate includes the component gravity load and the downward condenser load. The component gravity load refers to the load in the vertical direction on the anchored static components. at this time: (Component gravity load + condenser load).

Images