Improved design method for electric wedge gate valve

Abstract

The application provides an improved design method for an electric wedge gate valve, comprising: obtaining original valve structure parameters and original electric head parameters, including rated output torque and locked-rotor torque; calculating a minimum closing torque required for the original valve to meet sealing and a maximum bearing torque of the original valve rod; if the original rated output torque is less than the minimum closing torque, or the maximum bearing torque of the original valve rod is less than the original locked-rotor torque, then a candidate electric head that meets the condition of rated torque greater than or equal to the minimum closing torque and locked-rotor torque less than or equal to the current maximum bearing torque of the valve rod is selected from an electric head database; if a candidate electric head is selected, the model number is output, if no candidate electric head is selected, a valve rod strengthening scheme is generated, the bearing torque of the valve rod is updated, and then re-selection is performed until an improved scheme that meets the condition is obtained, and the model number of the candidate electric head or the valve rod strengthening scheme is output. Through double checking and iterative optimization, the sealing of the valve and the bending resistance of the valve rod are considered, and the safety and improvement efficiency of the nuclear electric wedge gate valve are improved.

Description

Technical Field

[0001] This invention relates to the field of nuclear power equipment selection technology, and in particular to an improved design method for electric wedge gate valves. Background Technology

[0002] Electric wedge gate valves used in nuclear power plant safety injection systems are critical fluid isolation devices, and existing valves of the same type generally suffer from design mismatch defects. The rated torque margin of the original valve's electric actuator is insufficient, and the valve seat clamping force cannot meet the sealing requirements. Long-term operation easily leads to internal leakage of the medium, compromising the integrity of the containment barrier. Simultaneously, the original valve stem thread section has a small outer diameter and limited single-thread load capacity. If the internal leakage problem is solved by replacing it with a high-torque actuator, the actuator's stall torque will exceed the valve stem's ultimate load capacity. Under commissioning or protection failure conditions, this can easily cause plastic bending of the valve stem, resulting in loss of valve opening and closing function, directly affecting the reliable operation of the emergency injection system. Current conventional solutions only replace the drive unit, failing to address the root cause of the valve stem strength mismatch. The industry lacks an integrated improvement design process; traditional retrofitting solutions often require cutting pipelines, damaging nuclear-grade piping, and lack standardized force calibration, seismic simulation, and complete qualification testing systems. This makes it difficult to meet the stringent operating conditions such as high temperature and pressure differential, earthquakes, and stall, posing a persistent nuclear safety hazard. Therefore, a complete design method that simultaneously achieves sealing reinforcement and valve stem bending resistance strengthening is urgently needed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an improved design method for electric wedge gate valves, addressing the problems existing in the prior art.

[0004] The technical solution adopted by this invention to solve its technical problem is: an improved design method for electric wedge gate valves, the method comprising the following steps: Step S1: Obtain the structural parameters of the original valve and the parameters of the original electric actuator, wherein the parameters of the original electric actuator include the original rated output torque and the original stall torque; Step S2: Calculate the minimum closing torque required for the original valve to meet the sealing requirements, and the maximum bearing torque of the original valve stem, based on the structural parameters. Step S3: If the original rated output torque is less than the minimum shut-off torque, proceed to step S5; Step S4: If the original valve stem maximum bearing torque is less than the original stall torque, proceed to step S5; Step S5: Based on the minimum closing torque and the current maximum valve stem bearing torque, select candidate electric actuators that meet the conditions from the electric actuator database; Step S6: If a candidate electric motor that meets the criteria is found, proceed to step S8; otherwise, proceed to step S7. Step S7: Generate a valve stem reinforcement scheme and calculate the maximum bearing torque of the reinforced valve stem. Use the maximum bearing torque of the reinforced valve stem as the current maximum bearing torque of the valve stem and return to step S5. Step S8: Output the model number of the candidate electric actuator or the valve stem reinforcement scheme as an improved design scheme for the valve.

[0005] Preferably, the structural parameters include the average diameter of the sealing surface. Valve seat angle Coefficient of friction of sealing surface and maximum operating pressure ; In step S2, calculating the minimum closing torque required for the original valve to meet the sealing requirements based on the structural parameters includes: According to the average diameter of the sealing surface The valve seat angle The coefficient of friction of the sealing surface and the maximum operating pressure The frictional resistance between the valve disc and the valve seat during the closing process of the electric wedge gate valve is calculated according to the following formula. : Based on the maximum operating pressure and the diameter of the valve stem The unbalanced force exerted by the medium on the valve stem during the closing process of the electric gate valve is calculated according to the following formula. : According to the diameter of the valve stem Based on the packing parameters, the packing friction resistance between the valve stem and the packing is calculated using the following formula. : in, This is the packing compression coefficient. This refers to the packing height; According to the valve disc friction resistance The valve stem unbalanced force and the frictional resistance of the packing The sum of these values ​​yields the minimum thrust required to close the electric gate valve. : According to the minimum thrust First thread conversion factor Preset safety factor And the efficiency of remote transmission mechanism The minimum closing torque is obtained according to the following formula. ; in, This refers to the minimum closing torque.

[0006] Preferably, the original stall torque Based on the original rated output torque The proportionality coefficient k between the stall torque and the rated torque of the original electric actuator is calculated according to the following formula: in, The original stall torque, This is the original rated output torque.

[0007] Preferably, the structural parameters further include the thread pitch diameter of the valve stem. Thread helix angle Half of the tooth angle of the trapezoidal thread The major diameter of the valve stem thread pitch The yield strength of the valve stem material Elastic modulus e, calculated length Length coefficient The tensile strength of the valve stem material ; In step S2, calculating the maximum bearing torque of the valve stem of the original valve includes: Based on the calculated length of the valve stem Length coefficient and the minor diameter of the valve stem thread Calculate the length-to-diameter ratio of the valve stem using the following formula. / : Based on the yield strength of the valve stem material and the elastic modulus Calculate the critical length-to-diameter ratio of the valve stem. : Compare the length-to-diameter ratio / With the critical aspect ratio : like / < The allowable compressive stress of the valve stem is then calculated according to the following formula. : And take: like ≤ / When the value is less than 120, the allowable compressive stress of the valve stem is calculated according to the following formula. : If 120≤ / If the value is less than 200, the allowable compressive stress of the valve stem is calculated according to the following formula. : According to the thread pitch diameter The thread helix angle Half of the trapezoidal thread profile angle Calculate the second thread conversion factor according to the following formula. : According to the allowable compressive stress The major diameter of the valve stem thread The pitch and the second thread conversion factor The critical moment of instability of the valve stem is calculated according to the following formula. : The instability critical torque This serves as the maximum bearing torque of the original valve stem.

[0008] Preferably, in step S2, calculating the maximum bearing torque of the valve stem of the original valve further includes: According to the original stall torque The second thread conversion coefficient and the minor diameter of the valve stem thread The actual maximum tensile stress of the valve stem is calculated according to the following formula. : If the actual maximum tensile stress Less than or equal to the tensile strength of the valve stem material If the actual maximum tensile stress is within the specified range, then the valve stem is determined to meet the tensile stress strength requirement. Greater than the tensile strength of the valve stem material If so, the valve stem reinforcement scheme is deemed not to meet the requirements.

[0009] Preferably, in step S5, the screening of candidate electric heads that meet the conditions includes: Compare the rated output torque of the candidate electric motors With the minimum closing torque The magnitude of the torque, and the stall torque of the candidate electric actuators are compared. With the current maximum load-bearing torque of the valve stem Size; If the rated output torque Greater than or equal to the minimum closing torque And the stall torque Less than or equal to the maximum bearing torque of the valve stem If so, the candidate electric head is determined to meet the condition.

[0010] Preferably, in step S7, the valve stem reinforcement scheme includes one or more of the following methods: Increase the outer diameter of the valve stem thread; Change the single-start thread of the valve stem to a multi-start thread; The material of the valve stem is replaced by a second alloy instead of a first alloy, and the yield strength of the second alloy is higher than that of the first alloy. Eliminate the relief groove structure of the valve stem and set the transition area between the thread and the smooth rod as a rounded transition or a natural transition.

[0011] Preferably, increasing the outer diameter of the valve stem thread includes: increasing the outer diameter of the valve stem thread from a first diameter to a second diameter, wherein the second diameter is equal to the outer diameter of the smooth portion of the valve stem; The step of changing the single-start thread of the valve stem to a multi-start thread includes changing the thread of the valve stem from a single-start thread to a double-start thread. The step of replacing the valve stem material with a second alloy from a first alloy includes replacing the valve stem material from X6CrNiCu17-04 with NC19FeNb.

[0012] Preferably, the method further includes: step S9: obtaining the verification result data of the prototype manufactured according to the improved design scheme output in step S8 in the verification test, and determining whether the verification result data meets the preset judgment conditions. If so, the improved design scheme is confirmed to meet the requirements.

[0013] Preferably, the verification test includes one or more of the following: mechanical calculation, simulation analysis, valve switching action test, locked rotor test, valve seat sealing test, water pressure test, cycle test, hot and cold alternation test, seismic performance test, thermal shock test, and high-energy pipeline fracture test; When the verification test includes a stall test, the verification result data includes the deformation data of the valve stem after the stall test, and the preset judgment condition includes that the deformation data of the valve stem is less than or equal to the deformation threshold.

[0014] The beneficial effect of this invention is that this application provides an improved design method for an electric wedge gate valve, the method comprising the following steps: Step S1: Obtain the structural parameters of the original valve and the parameters of the original electric actuator, wherein the parameters of the original electric actuator include the original rated output torque and the original stall torque; Step S2: Calculate the minimum closing torque required for the original valve to meet the sealing requirements, and the original maximum bearing torque of the valve stem, based on the structural parameters; Step S3: If the original rated output torque is less than the minimum closing torque, proceed to step S5; Step S4: If the original valve stem maximum bearing torque is less than the original stall torque, proceed to step S5; Step S5: Based on the minimum closing torque and the current valve stem maximum bearing torque, select candidate electric actuators that meet the conditions from the electric actuator database; Step S6: If a candidate electric actuator that meets the conditions is selected, proceed to step S8; if not, proceed to step S7; Step S7: Generate a valve stem reinforcement scheme and calculate the reinforced valve stem maximum bearing torque, using the reinforced valve stem maximum bearing torque as the current valve stem maximum bearing torque, and return to step S5; Step S8: Output the model of the candidate electric actuator or the valve stem reinforcement scheme as the improved design scheme for the valve. This application, through dual verification of sealing torque and valve stem bearing capacity, iteratively optimizes the valve stem and matches the electric actuator when the original design does not meet the requirements until an improved scheme that meets the sealing and strength requirements is obtained. This achieves the goal of avoiding valve stem bending failure while ensuring sealing reliability, thus improving the safety and improvement efficiency of nuclear-grade electric wedge gate valves. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a logic flowchart of the improved design method for electric wedge gate valves according to the present invention. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the invention are now described in detail with reference to the accompanying drawings. In the following description, specific details such as particular structures and techniques are set forth for illustrative purposes and not for limitation, so as to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0017] like Figure 1 As shown, Figure 1 This is a logic flowchart of the improved design method for electric wedge gate valves according to the present invention.

[0018] The technical solution adopted by this invention to solve its technical problem is: an improved design method for an electric wedge gate valve, wherein the electric wedge gate valve includes a valve body, a valve cover, a valve disc, a valve stem, a valve stem nut, and an electric actuator, wherein the electric actuator engages with the valve stem via the valve stem nut to drive the valve stem to rise and fall, thereby actuating the valve disc to open and close the valve; the method includes the following steps: Step S1: Obtain the structural parameters of the original valve and the parameters of the original electric actuator. The parameters of the original electric actuator include the original rated output torque and the original stall torque. In this step, it should be noted that the original electric motor parameters can be obtained directly from the equipment nameplate or factory documentation.

[0019] Step S2: Calculate the minimum closing torque required for the original valve to meet the sealing requirements, and the maximum bearing torque of the original valve stem, based on the structural parameters; In this step, it should be noted that the minimum closing torque is based on the sum of various resistances that need to be overcome during valve closure, calculated using a thread conversion factor and corrected for a safety factor. Specifically, the closing resistance includes the frictional resistance between the valve disc and the valve seat, the unbalanced force exerted by the medium on the valve stem, and the frictional resistance between the valve stem and the packing. The sum of these three is the minimum thrust required to close the valve. This thrust is converted into torque using the first thread conversion factor, multiplied by the safety factor, and divided by the efficiency of the remote transmission mechanism to obtain the minimum closing torque. The original maximum bearing torque of the valve stem is the critical torque for valve stem instability. It is calculated in segments based on the geometric and material parameters of the valve stem, combined with the comparison between the valve stem's length-to-diameter ratio and the critical length-to-diameter ratio. Its physical meaning is the maximum torque that the valve stem can withstand before the pressure rod becomes unstable. These two torques respectively characterize "how much force is needed to close the valve" and "how much force the valve stem can withstand without bending," serving as the quantitative basis for subsequent judgment and selection.

[0020] Step S3: If the original rated output torque is less than the minimum closing torque, proceed to step S5; In this step, it should be noted that this judgment step is used to identify whether the original electric actuator has insufficient sealing torque margin. If the original rated output torque is less than the minimum closing torque, it indicates that the original electric actuator cannot provide sufficient clamping force to achieve a reliable seal of the valve seat under rated operating conditions, i.e., there is a risk of "not closing tightly", and it is necessary to rematch the electric actuator or strengthen the valve stem through subsequent steps; if the original rated output torque is greater than or equal to the minimum closing torque, the sealing torque margin is sufficient, and there is no need to trigger the improvement process due to sealing problems.

[0021] Step S4: If the original maximum bearing torque of the valve stem is less than the original stall torque, proceed to step S5; In this step, it should be noted that this judgment step is used to identify whether the original valve stem has insufficient load-bearing capacity. If the maximum load-bearing torque of the original valve stem is less than the stall torque of the original electric actuator, it indicates that under stall conditions, the maximum torque output by the electric actuator has exceeded the valve stem's load-bearing limit, and the valve stem is at risk of instability and bending. If the maximum load-bearing torque of the original valve stem is greater than or equal to the original stall torque, the valve stem has sufficient load-bearing capacity and will not bend due to stall. The above steps S3 and S4 are parallel judgments. As long as either the sealing torque is insufficient or the valve stem load-bearing capacity is insufficient, the subsequent improvement process is triggered. If neither condition is met, it indicates that the original design already meets the requirements and no improvement is needed.

[0022] Step S5: Based on the minimum closing torque and the current maximum valve stem bearing torque, select candidate electric actuators that meet the conditions from the electric actuator database; In this step, it's important to note that the screening criteria include two inequalities: the rated output torque of the candidate electric actuator should be greater than or equal to the minimum closing torque (to ensure a tight seal), and the stall torque of the candidate electric actuator should be less than or equal to the current maximum valve stem bearing torque (to prevent stem bending). The electric actuator database pre-stores parameters such as rated output torque, stall torque, output speed, weight, and interface dimensions for various electric actuator models. During screening, these parameters are matched one by one, outputting candidate models that simultaneously meet both constraints. Here, "current maximum valve stem bearing torque" refers to the original maximum valve stem bearing torque during the initial screening. If the valve stem is subsequently strengthened in step S7, this value is updated to the strengthened maximum valve stem bearing torque.

[0023] Step S6: If a candidate electric motor that meets the criteria is found, proceed to step S8; otherwise, proceed to step S7. In this step, it should be noted that this judgment step is used to determine whether valve stem reinforcement is required. If a candidate electric actuator that meets the conditions is found, it means that without changing the original valve stem, simply replacing the electric actuator can simultaneously meet the sealing and strength requirements, and valve stem reinforcement is not necessary. If no candidate electric actuator that meets the conditions is found, it means that the existing electric actuator database cannot find a model that simultaneously meets the requirements of "rated torque ≥ minimum closing torque" and "locked torque ≤ current valve stem load limit". In this case, valve stem reinforcement is required to improve its load-bearing capacity before re-selection.

[0024] Step S7: Generate a valve stem reinforcement scheme and calculate the maximum bearing torque of the reinforced valve stem. Use the maximum bearing torque of the reinforced valve stem as the current maximum bearing torque of the valve stem and return to step S5. In this step, it should be noted that the valve stem strengthening scheme includes one or more of the following: increasing the outer diameter of the valve stem thread, changing the single-start thread to a multi-start thread, replacing the valve stem material with an alloy with higher yield strength, and eliminating the relief groove and setting the transition area as a rounded transition or a natural transition. The maximum load-bearing torque of the strengthened valve stem is recalculated based on the strengthened valve stem's geometric and material parameters. After updating the current maximum load-bearing torque of the valve stem, return to step S5, and re-select the electric actuator from the database using the new load-bearing limit until a candidate electric actuator that meets the conditions is found.

[0025] Step S8: Output the model of the candidate electric actuator or the valve stem reinforcement scheme as an improved design scheme for the valve.

[0026] In this step, it should be noted that the output depends on the actual execution path: if step S6 directly filters the candidate electric head from S5 without executing S7, the output will be the model of the candidate electric head (i.e., the "replace electric head only" solution); if step S6 does not filter the candidate electric head but it is filtered again after strengthening in S7, the output will be the model of the candidate electric head and the corresponding valve stem strengthening solution (i.e., the "replace electric head + strengthen valve stem" solution); if the original valve stem's load-bearing capacity is much greater than the original stall torque and there is only a problem of insufficient sealing torque, then only the valve stem strengthening solution may be output (i.e., the "strengthen valve stem only" solution, which increases the thread conversion coefficient by strengthening and changing the thread parameters, thereby changing the required set torque under the same thrust). The output improved design solution can be directly used for prototype manufacturing and subsequent verification tests.

[0027] Furthermore, in an optional embodiment, the structural parameters include the average diameter of the sealing surface. Valve seat angle Coefficient of friction of sealing surface and maximum operating pressure ; In step S2, the minimum closing torque required for the original valve to meet the sealing requirements is calculated based on the structural parameters, including: Based on the average diameter of the sealing surface Valve seat angle Coefficient of friction of sealing surface and maximum operating pressure Calculate the valve disc frictional resistance between the valve disc and the valve seat during the closing process of the electric wedge gate valve using the following formula. : Based on maximum operating pressure and the diameter of the valve stem Calculate the unbalanced force on the valve stem exerted by the medium during the closing process of the electric gate valve using the following formula. : According to the diameter of the valve stem Based on the packing parameters, calculate the packing friction resistance between the valve stem and the packing using the following formula. : in, This is the packing compression coefficient. Where S is the packing height, and S is the contact area between the valve stem and the packing. ; Based on the valve disc friction resistance Unbalanced force on valve stem Frictional resistance of packing The sum of these values ​​yields the minimum thrust required to close the electric gate valve. : Based on minimum thrust First thread conversion factor Preset safety factor And the efficiency of remote transmission mechanism The minimum closing torque can be obtained using the following formula. ; in, This is the minimum closing torque.

[0028] Specifically, the valve disc frictional resistance FDP reflects the friction between the sealing surfaces during the gate's wedging process, and its value depends on the average diameter of the sealing surfaces, the valve seat angle, the coefficient of friction of the sealing surfaces, and the medium pressure; the valve stem unbalanced force FSE reflects the axial action of the medium pressure on the valve stem, and is proportional to the medium pressure and the square of the valve stem diameter; the packing frictional resistance FSP reflects the sliding friction between the valve stem and the packing, and is proportional to the packing compression coefficient, the valve stem diameter, and the packing height. The sum of these three resistances is the minimum thrust Fclose required to close the electric gate valve. This thrust is converted into torque by the first thread conversion factor SF (determined by the thread pitch diameter, thread helix angle, and trapezoidal thread profile angle), and then multiplied by the safety factor. (Typically, it is taken as 1.2 to 1.5; in this embodiment, it is taken as 1.3) and divided by the efficiency of the remote transmission mechanism. (Take 1 if there is no remote transmission mechanism) to obtain the minimum closing torque Mseal. This minimum closing torque is the lower limit of the rated output torque that the electric actuator needs to provide.

[0029] Furthermore, in an optional embodiment, the original stall torque Based on the original rated output torque The proportionality coefficient k between the stall torque and the rated torque of the original electric actuator is calculated according to the following formula: in, The original stall torque, This is the original rated output torque.

[0030] Specifically, the proportional coefficient k is an inherent characteristic parameter of the electric actuator. Different models of electric actuators have different k values, typically ranging from 1.1 to 2.0. This coefficient can be obtained from the electric actuator's manufacturer's documentation or through actual measurement. The stall torque is the maximum torque the electric actuator can output when the output shaft is jammed; it is a key parameter for determining whether the valve stem will bend due to overload.

[0031] Furthermore, in an optional embodiment, the structural parameters also include the thread pitch diameter of the valve stem. Thread helix angle Half of the tooth angle of the trapezoidal thread Major diameter of valve stem thread pitch Yield strength of valve stem material Elastic modulus e, calculated length Length coefficient Tensile strength of valve stem material ; In step S2, calculating the maximum bearing torque of the valve stem of the original valve includes: Based on the calculated length of the valve stem Length coefficient minor diameter of valve stem thread Calculate the length-to-diameter ratio of the valve stem using the following formula. / : Based on the yield strength of the valve stem material and elastic modulus Calculate the critical length-to-diameter ratio of the valve stem. : Compare aspect ratios / Compared with the critical aspect ratio : like / < The allowable compressive stress of the valve stem is then calculated using the following formula. : And take: like ≤ / When the value is less than 120, the allowable compressive stress of the valve stem is calculated according to the following formula. : If 120≤ / If the value is less than 200, the allowable compressive stress of the valve stem is calculated using the following formula. : According to the thread pitch diameter Thread helix angle Half of the tooth angle of the trapezoidal thread Calculate the second thread conversion factor according to the following formula. : According to allowable compressive stress Major diameter of valve stem thread pitch Second thread conversion factor Calculate the critical moment of instability of the valve stem using the following formula. : The critical moment of instability As the original valve stem's maximum bearing torque.

[0032] Specifically, the maximum load-bearing capacity is calculated based on the column stability theory. The allowable compressive stress of the valve stem is calculated in segments based on the comparison between the length-to-diameter ratio (L / D ratio) and the critical L / D ratio. When the L / D ratio is less than the critical L / D ratio, the strength failure mode is used, taking the smaller value between the allowable compressive stress calculated from the yield strength and half the tensile strength. When the L / D ratio is greater than or equal to the critical L / D ratio, the instability failure mode is used, calculating the allowable compressive stress in segments based on the ratio of the elastic modulus to the L / D ratio. (Second thread conversion factor) This is used to convert the axial compressive stress on the critical section of the valve stem into the corresponding torque. The final instability critical torque Mcr is the maximum torque that the valve stem can withstand before the pressure rod buckles, also known as the "maximum bearing torque of the valve stem".

[0033] Furthermore, in an optional embodiment, step S2, calculating the maximum bearing torque of the original valve stem, further includes: Based on the original stall torque Second thread conversion factor minor diameter of valve stem thread Calculate the actual maximum tensile stress of the valve stem using the following formula. : If the actual maximum tensile stress Less than or equal to the tensile strength of the valve stem material If the actual maximum tensile stress is within the required range, then the valve stem is deemed to meet the tensile strength requirement. Greater than the tensile strength of the valve stem material If so, the valve stem reinforcement scheme is deemed not to meet the requirements.

[0034] Specifically, this step involves checking the tensile stress strength of the valve stem to verify whether the actual tensile stress at the critical section of the valve stem under stall torque exceeds the tensile strength of the material. If the actual maximum tensile stress is less than or equal to the tensile strength of the material, the valve stem will not fracture under stall conditions. If the actual maximum tensile stress is greater than the tensile strength of the material, the valve stem is at risk of fracture under stall conditions, and the current drive assembly cannot meet the strength requirements under stall conditions, requiring readjustment of the assembly parameters and re-checking. It should be noted that the tensile stress strength check and the aforementioned instability critical moment check complement each other: the instability check prevents the valve stem from bending under compression, while the tensile stress check prevents the valve stem from fracturing under tension; both are necessary components of valve stem strength verification.

[0035] Further, in an optional embodiment, step S5, screening candidate motor heads that meet the conditions includes: Compare the rated output torque of candidate electric motors With minimum closing torque The magnitude of the torque, and the stall torque of the candidate electric actuators. With the current maximum load-bearing torque of the valve stem Size; If the rated output torque Greater than or equal to minimum closing torque And stall torque Less than or equal to the maximum bearing torque of the valve stem If so, the candidate electric head is determined to meet the conditions.

[0036] Specifically, the selection criteria include two inequalities that must be satisfied simultaneously, corresponding to the two core objectives of this invention: The rated output torque constraint ensures that the electric actuator has sufficient torque to reliably close the valve and press the sealing pair, solving the "not closing tightly" problem; the stall torque constraint ensures that even under the most severe stall conditions, the maximum torque output by the electric actuator does not exceed the valve stem's load-bearing limit, solving the "stem bending" problem. Only electric actuator models that simultaneously meet both conditions can guarantee both sealing reliability and structural integrity. If a candidate electric actuator only meets the first condition but not the second, although it can close the valve tightly, it may cause the valve stem to bend under abnormal operating conditions, and therefore cannot be selected.

[0037] Furthermore, in an optional embodiment, step S7, generating the valve stem reinforcement scheme includes one or more of the following methods: Increase the outer diameter of the valve stem thread; Change the single-start thread of the valve stem to a multi-start thread; The valve stem material is replaced by a second alloy, which has a higher yield strength than the first alloy. Eliminate the relief groove structure of the valve stem and set the transition area between the thread and the smooth rod as a rounded transition or a natural transition.

[0038] Specifically, the four strengthening methods described above enhance the valve stem's load-bearing capacity from different dimensions: increasing the thread outer diameter directly increases the area of ​​the valve stem's critical section, thereby improving its compressive and bending resistance; changing a single-start thread to a multi-start thread (such as a double-start thread) increases the thread contact area and transmission efficiency, reducing stress per unit area; replacing the material with one of higher yield strength improves the load-bearing limit at the material level; eliminating the undercut and replacing it with a rounded transition eliminates stress concentration points, preventing crack initiation and propagation. These four methods can be used individually or in any combination depending on the actual situation. When using only one method can meet the valve stem's load-bearing requirements, there is no need to use other methods, achieving the improvement goal with minimal modifications.

[0039] Further, in an optional embodiment, increasing the thread outer diameter of the valve stem includes: increasing the thread outer diameter of the valve stem from a first diameter to a second diameter, the second diameter being equal to the outer diameter of the smooth portion of the valve stem; Changing the single-start thread of the valve stem to a multi-start thread includes changing the single-start thread of the valve stem to a double-start thread. Replacing the valve stem material with the second alloy from the first alloy includes replacing the valve stem material from X6CrNiCu17-04 with NC19FeNb.

[0040] Specifically, the three improvements mentioned above have been practically applied and proven effective on the VELAN DN80 valve at the Yangjiang Nuclear Power Plant. The specific values ​​of the first and second diameters depend on the outer diameter of the original valve stem. In this embodiment, the first diameter is 24mm (original thread outer diameter), and the second diameter is 28mm (original stem outer diameter). After the improvement, the thread outer diameter is equal to the stem outer diameter, eliminating stress concentration caused by abrupt changes in cross-section. Changing the thread from a single-start to a double-start increases the thread contact area, improves transmission efficiency, reduces pressure per unit area, relatively lowers the friction coefficient, and reduces wear on the valve stem nut. Replacing the material from X6CrNiCu17-04 (martensitic stainless steel) to NC19FeNb (nickel-based alloy) increases the tensile strength from 965MPa to 1275MPa (a 32% increase) and the yield strength from 793MPa to 1035MPa (a 30.5% increase). Simultaneously, the impact energy testing requirement (≥45J) is increased, resulting in a significant improvement in both the material's strength and toughness.

[0041] Furthermore, in an optional embodiment, the method further includes: step S9: obtaining the verification result data of the prototype manufactured according to the improved design scheme output in step S8 in the verification test, determining whether the verification result data meets the preset judgment conditions, and if so, confirming that the improved design scheme meets the requirements.

[0042] Specifically, the improved design scheme output in step S8 is a theoretical calculation result, which needs to be verified through a physical prototype to confirm its effectiveness under actual working conditions. The purpose of the verification test is to confirm the correctness of the theoretical calculation and selection results through physical testing, including but not limited to mechanical calculations, simulation analysis, valve switching operation tests, stall tests, and valve seat sealing tests. If all verification result data meet the preset judgment conditions, the improved design scheme is confirmed to meet the actual use requirements, and the selection is completed; if any key verification result data does not meet the preset judgment conditions, the cause needs to be analyzed and the component parameters readjusted, and the calculation, selection, and verification process is repeated until all key verifications are passed, and the selection is confirmed to be complete.

[0043] In a specific application example, the prototype improved according to this scheme completed all verification items, including valve assembly, operation test, locked-rotor test, sealing test, and post-test disassembly inspection. During the operation test, the valve operated smoothly without jamming, and the electric operation switching time was 12-13 seconds (meeting the 10-20 seconds requirement). In the locked-rotor test, the valve stem showed no bending or deformation under 400V voltage for 7 seconds. The leakage rates before and after the locked-rotor test were 0.10ml / 0.50ml (forward) and 0.12ml / 0.50ml (forward) respectively (both meeting the requirement of ≤8.0cm³ / h, with an allowable leakage rate of 0.67ml over 5 minutes). Post-test disassembly inspection revealed no abnormal damage or deformation to any key components. All verification items met the preset judgment conditions, confirming that the improved design scheme meets the requirements.

[0044] Furthermore, in an optional embodiment, the verification test includes one or more of the following: mechanical calculation, simulation analysis, valve switching action test, locked rotor test, valve seat sealing test, hydraulic pressure test, cyclic test, thermal alternation test, seismic performance test, thermal shock test, and high-energy pipeline fracture test; When the verification test includes a stall test, the verification result data includes the deformation data of the valve stem after the stall test, and the preset judgment condition includes that the deformation data of the valve stem is less than or equal to the deformation threshold.

[0045] Specifically, the aforementioned verification tests cover a complete verification system, from theoretical calculations and simulation analysis to physical testing. Mechanical calculations verify whether the strength of each key component meets requirements under maximum stall torque; simulation analysis verifies the natural frequency and stress response of the entire valve under seismic loads; the valve opening and closing operation test verifies whether the valve's opening and closing function is smooth under rated torque; the stall test verifies whether the valve stem undergoes bending deformation under stall conditions; the sealing test verifies whether the leakage of the valve seat under forward and reverse pressures meets requirements; the hydrostatic test verifies the integrity of the pressure-bearing boundary; the cyclic test verifies the valve's durability; the thermal cycling test verifies the sealing performance under drastic temperature changes; the seismic performance test verifies seismic resistance; the thermal shock test verifies structural integrity under thermal shock; and the high-energy pipeline fracture test verifies the interruption capability under accident conditions. Each test must meet the corresponding acceptance criteria to pass.

[0046] In the stall test, the deformation data of the valve stem after the stall test includes bending deformation and visible deformation. The deformation threshold is a preset allowable deformation amount or visible deformation judgment standard. If the actual measured deformation data is less than or equal to the deformation threshold (e.g., no bending deformation or visible deformation of the valve stem), the valve stem is deemed to meet the strength requirements under stall conditions, and the stall test verification is passed. If the actual measured deformation data is greater than the deformation threshold (e.g., visible bending deformation of the valve stem), the valve stem is deemed not to meet the strength requirements under stall conditions, and the component parameters need to be readjusted and the verification is carried out again. After the test, the entire machine needs to be disassembled and inspected to confirm whether there is any abnormal damage or deformation of the key components.

[0047] In a specific application example, the valve stall test was conducted at 400V for 7 seconds. During the test, the valve operated normally, moved flexibly, and the valve stem showed no bending. Disassembly and inspection after stalling revealed no visible deformation of the valve stem or valve stem nut; however, an indentation (approximately 11mm in diameter and 0.5mm deep) was found at the contact point between the valve disc and the valve stem head. Analysis indicated that this was due to the valve stem material strength (NC19FeNb) being greater than the valve disc material strength. This indentation did not cause valve disc material failure and remained within acceptable limits. Post-test disassembly and inspection confirmed no abnormal damage or deformation to any components, and all verification indicators met the preset judgment conditions, thus the verification test was passed.

[0048] The test parameters and acceptance criteria for each project are shown in Table 1.

[0049] The impact of the improved valve stem and valve stem nut on the original valve qualification test is analyzed in Table 2.

[0050] Table 2 Comparative Analysis of Valve Stem and Valve Stem Nut Qualification Tests The impact of the replaced electric head on the original qualification test is analyzed in Table 3.

[0051] Table 3 Comparative Analysis of Electric Head Qualification Tests The verification results of the valve body under various stress paths are shown in Table 4.

[0052] Table 4 Valve Body Stress Verification Results in, For the overall film stress, For a localized membrane stress, Let S be the primary bending stress, and S be the allowable stress.

[0053] The verification results of the valve cover under each stress path are shown in Table 5.

[0054] Table 5. Stress verification results for valve cover The verification results of the gate plate under various stress paths are shown in Table 6.

[0055] Table 6. Stress Verification Results of Gate Plate The verification results of the valve stem under various stress paths are shown in Table 7.

[0056] Table 7 Valve stem stress verification results The verification results of other components such as valve stem nut, transmission sleeve and transmission key under various stress paths are shown in Table 8.

[0057] Table 8 Stress verification results for other components The evaluation results of the body cover and electrical connections under each evaluation criterion are shown in Table 9.

[0058] Table 9. Evaluation Results of Electrical Connections Further, in an optional embodiment, in step S6, determining whether the verification result data meets the preset judgment condition includes: if the verification test includes a stall test, then the verification result data includes the deformation data of the valve stem after the stall test; the preset judgment condition includes: the deformation data of the valve stem is less than or equal to the deformation threshold; if the deformation data is less than or equal to the deformation threshold, then the preset judgment condition is met.

[0059] Specifically, in the stall test, the deformation data of the valve stem after the stall test includes bending deformation and visible deformation. The deformation threshold is a preset allowable deformation amount or visible deformation judgment standard. If the actual measured deformation data is less than or equal to the deformation threshold (e.g., no bending deformation or visible deformation of the valve stem), the valve stem is deemed to meet the strength requirements under stall conditions, and the stall test verification is passed; if the actual measured deformation data is greater than the deformation threshold (e.g., visible bending deformation of the valve stem), the valve stem is deemed not to meet the strength requirements under stall conditions, and the component parameters need to be readjusted and the verification is carried out again. After the test, the entire machine also needs to be disassembled and inspected to confirm whether there is any abnormal damage or deformation of the key components.

[0060] The items and requirements for various tests of the entire valve are shown in Table 10.

[0061] Table 10 Valve Testing Requirements In one specific embodiment, the valve stem and valve stem nut were redesigned, with the specific improvements as follows: Regarding the improvement of the valve stem structure, the trapezoidal thread has been changed from the original specification Tr24×5 (single-ended) to Tr28×5 (double-ended) to enhance the axial load capacity and impact resistance of the valve stem. At the same time, the thread end is shortened and a rounded corner transition is adopted. The transition area between the keyway section and the smooth valve stem has been improved from a relief groove to a natural transition to avoid damage to the packing. The transition area at the back seal has been improved from a relief groove to a rounded corner structure to improve stress distribution.

[0062] Regarding the improvement of valve stem material, the original X6CrNiCu17-04 material was replaced with NC19FeNb. The improved material has significantly increased tensile strength and yield strength, and an impact energy test requirement (≥45J) was added. The improved valve stem has a tensile strength of 1275MPa and a yield strength of 1035MPa, while the original valve stem has a tensile strength of 965MPa and a yield strength of 793MPa. See Table 11 for a comparison of the mechanical properties of valve stem materials.

[0063] Table 11 Comparison of Mechanical Properties of Valve Stem Materials The improved valve stem uses RCC-MM4102NC19FeNb (nickel-based alloy), while the original valve stem used RCC-MM5110X6CrNiCu17-04 (martensitic stainless steel). The chemical composition comparison of the two is shown in Table 12.

[0064] Table 12 Comparison of Chemical Composition of Valve Stem Materials Regarding the improvement of the valve stem nut, considering the supply conditions after domestic production, the material of the valve stem nut needs to be improved. The improved valve stem nut uses QAl9-4 aluminum bronze, while the original valve stem nut used CuZn+class2 copper alloy. The mechanical properties of the two are compared in Table 13. The tensile strength of the improved valve stem nut is 540MPa, the yield strength is 280MPa, and the allowable stress is 186.7MPa; the tensile strength of the original valve stem nut is 570MPa, the yield strength is 280MPa, and the allowable stress is 186.7MPa. The yield strength and allowable stress of the two are comparable, and the tensile strength is slightly reduced but still meets the usage requirements. Both the improved and original valve stem nuts are made primarily of copper (Cu), with other components being similar, ensuring that the mechanical properties remain at a comparable level to the original.

[0065] Table 13 Comparison of Mechanical Properties of Valve Stem Nuts The improved valve stem nut uses QAl9-4 aluminum bronze, while the original valve stem nut used CuZn+class2 copper alloy. The chemical composition comparison of the two is shown in Table 14.

[0066] Table 14 Comparison of Chemical Composition of Valve Stem Nuts Regarding the improvement of the connecting bolts, due to interference from the on-site pipeline layout, the electric actuator needed to be raised, and the length of the connecting bolts was increased from 57mm to 100mm. The improved connecting bolts use ASTM A193B7 material, while the original connecting bolts used C1.8.8 material. The strength comparison between the two is shown in Table 15. The tensile strength of the improved connecting bolts is 860MPa, the yield strength is 720MPa, and the hardness is ≤35HRC; the tensile strength of the original connecting bolts is 800MPa, the yield strength is 640MPa, and the hardness is 22-32HRC. The tensile strength and yield strength of the improved connecting bolts are slightly higher than those of the original connecting bolts, which can meet the strength requirements after the lengthening and ensure the reliability of the connection between the electric actuator and the valve.

[0067] Table 15 Comparison of Material Strength of Connecting Bolts Regarding the selection of the electric actuator, the base of the electric actuator was determined to be 2HA3.2 based on the rated torque and maximum load torque of the valve. Through stall tests with different power and speed configurations of the electric actuator, and based on the test results and valve calculations, the final electric actuator model was determined to be 2HA3022 with an output speed of 40 r / min. Considering the domestic substitution of imported electric actuators, the design was optimized in terms of size, weight, and interface: the handwheel diameter was changed from 450mm to 380mm to meet the on-site installation space requirements; all flange interfaces are F14, with the concave inner claw changed to a convex claw, and the flange height increased by 40mm to accommodate on-site installation brackets; the control cover material was changed from ductile iron to aluminum, and the observation window material was changed from tempered glass to polycarbonate, reducing the overall weight; the wiring cover material was changed from ductile iron to aluminum, further reducing the overall weight; the disc spring was reconfigured according to a set torque of 280Nm to ensure that the torque adjustment range meets the valve requirements; the torque cam was designed with a sharp angle shape, making the switch triggering direct and reliable, eliminating torque variations caused by different switch triggering positions; considering the possibility of increased power supply pressure within the power plant, a stall test at 400VAC voltage was added to the electric actuator factory test. The differences in the electric actuator's external dimensions have been verified and will not affect the installation at the same location in Units 1-6, and the wiring of the electric actuator is consistent with that of the maintenance electric actuators in a certain nuclear power plant, which can reduce the risk of wiring errors. The dimensions of the 2HA3022 model electric motor head are shown in Table 16.

[0068] Table 162HA3022 Model Electric Head Size Table The electric actuator has a set torque of 280 Nm and a 400V stall torque of ≤504 Nm, as shown in Table 17. Since the electric actuator's weight exceeds that of the replacement actuator, additional seismic analysis of the entire valve and pipeline mechanics calculations are required to verify the structural integrity of the replaced valve and the pipeline's load-bearing capacity under seismic loads. The worm gear lead angle of this model of electric actuator is 4.5°, which is less than the equivalent friction angle of 5.7°. Therefore, the electric actuator has self-locking properties, effectively preventing the valve from accidentally opening due to external forces after it has been fully closed.

[0069] Table 172HA3022 Model Electric Head Parameter Table The main improvements to each component and the differences from the original product, as well as their impact analysis, are shown in Table 18.

[0070] Table 18 Summary of Design Improvements It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An improved design method for an electric wedge gate valve, characterized in that, The method includes the following steps: Step S1: Obtain the structural parameters of the original valve and the parameters of the original electric actuator, wherein the parameters of the original electric actuator include the original rated output torque and the original stall torque; Step S2: Calculate the minimum closing torque required for the original valve to meet the sealing requirements, and the maximum bearing torque of the original valve stem, based on the structural parameters. Step S3: If the original rated output torque is less than the minimum shut-off torque, proceed to step S5; Step S4: If the original valve stem maximum bearing torque is less than the original stall torque, proceed to step S5; Step S5: Based on the minimum closing torque and the current maximum valve stem bearing torque, select candidate electric actuators that meet the conditions from the electric actuator database; Step S6: If a candidate electric motor that meets the criteria is found, proceed to step S8; otherwise, proceed to step S7. Step S7: Generate a valve stem reinforcement scheme and calculate the maximum bearing torque of the reinforced valve stem. Use the maximum bearing torque of the reinforced valve stem as the current maximum bearing torque of the valve stem and return to step S5. Step S8: Output the model number of the candidate electric actuator or the valve stem reinforcement scheme as an improved design scheme for the valve.

2. The improved design method for an electric wedge gate valve according to claim 1, characterized in that, The structural parameters include the average diameter of the sealing surface. Valve seat angle Coefficient of friction of sealing surface and maximum operating pressure ; In step S2, calculating the minimum closing torque required for the original valve to meet the sealing requirements based on the structural parameters includes: According to the average diameter of the sealing surface The valve seat angle The coefficient of friction of the sealing surface and the maximum operating pressure The frictional resistance between the valve disc and the valve seat during the closing process of the electric wedge gate valve is calculated according to the following formula. : Based on the maximum operating pressure and the diameter of the valve stem The unbalanced force exerted by the medium on the valve stem during the closing process of the electric gate valve is calculated according to the following formula. : According to the diameter of the valve stem Based on the packing parameters, the packing friction resistance between the valve stem and the packing is calculated using the following formula. : in, This is the packing compression coefficient. This refers to the packing height; According to the valve disc friction resistance The valve stem unbalanced force and the frictional resistance of the packing The sum of these values ​​yields the minimum thrust required to close the electric gate valve. : According to the minimum thrust First thread conversion factor Preset safety factor And the efficiency of remote transmission mechanism The minimum closing torque is obtained according to the following formula. ; in, This is the minimum closing torque.

3. The improved design method for an electric wedge gate valve according to claim 1, characterized in that, The original stall torque According to the original rated output torque The proportionality coefficient k between the stall torque and the rated torque of the original electric actuator is calculated according to the following formula: in, The original stall torque, This is the original rated output torque.

4. The improved design method for an electric wedge gate valve according to claim 3, characterized in that, The structural parameters also include the thread pitch diameter of the valve stem. Thread helix angle Half of the tooth angle of the trapezoidal thread The major diameter of the valve stem thread pitch The yield strength of the valve stem material Elastic modulus e, calculated length Length coefficient The tensile strength of the valve stem material ; In step S2, calculating the maximum bearing torque of the valve stem of the original valve includes: Based on the calculated length of the valve stem Length coefficient and the minor diameter of the valve stem thread Calculate the length-to-diameter ratio of the valve stem using the following formula. / : Based on the yield strength of the valve stem material and the elastic modulus Calculate the critical length-to-diameter ratio of the valve stem. : Compare the length-to-diameter ratio / With the critical aspect ratio : like / < The allowable compressive stress of the valve stem is then calculated according to the following formula. : And take: like ≤ / When the value is less than 120, the allowable compressive stress of the valve stem is calculated according to the following formula. : If 120≤ / If the value is less than 200, the allowable compressive stress of the valve stem is calculated according to the following formula. : According to the thread pitch diameter The thread helix angle Half of the trapezoidal thread profile angle Calculate the second thread conversion factor according to the following formula. : According to the allowable compressive stress The major diameter of the valve stem thread The pitch and the second thread conversion factor The critical moment of instability of the valve stem is calculated according to the following formula. : The instability critical torque This serves as the maximum bearing torque of the original valve stem.

5. The improved design method for an electric wedge gate valve according to claim 4, characterized in that, In step S2, calculating the maximum bearing torque of the valve stem of the original valve further includes: According to the original stall torque The second thread conversion coefficient and the minor diameter of the valve stem thread The actual maximum tensile stress of the valve stem is calculated according to the following formula. : If the actual maximum tensile stress Less than or equal to the tensile strength of the valve stem material If the actual maximum tensile stress is within the specified range, then the valve stem is determined to meet the tensile stress strength requirement. Greater than the tensile strength of the valve stem material If so, the valve stem reinforcement scheme is deemed not to meet the requirements.

6. The improved design method for an electric wedge gate valve according to claim 1, characterized in that, In step S5, the screening of candidate electric motors that meet the conditions includes: Compare the rated output torque of the candidate electric motors With the minimum closing torque The magnitude of the torque, and the stall torque of the candidate electric actuators are compared. With the current maximum load-bearing torque of the valve stem Size; If the rated output torque Greater than or equal to the minimum closing torque And the stall torque Less than or equal to the maximum bearing torque of the valve stem If so, the candidate electric head is determined to meet the condition.

7. The improved design method for an electric wedge gate valve according to claim 1, characterized in that, In step S7, the valve stem reinforcement scheme includes one or more of the following methods: Increase the outer diameter of the valve stem thread; Change the single-start thread of the valve stem to a multi-start thread; The material of the valve stem is replaced by a second alloy instead of a first alloy, and the yield strength of the second alloy is higher than that of the first alloy. Eliminate the relief groove structure of the valve stem and set the transition area between the thread and the smooth rod as a rounded transition or a natural transition.

8. The improved design method for an electric wedge gate valve according to claim 7, characterized in that, Increasing the outer diameter of the valve stem thread includes: increasing the outer diameter of the valve stem thread from a first diameter to a second diameter, wherein the second diameter is equal to the outer diameter of the smooth portion of the valve stem; The step of changing the single-start thread of the valve stem to a multi-start thread includes changing the thread of the valve stem from a single-start thread to a double-start thread. The step of replacing the valve stem material with a second alloy from a first alloy includes replacing the valve stem material from X6CrNiCu17-04 with NC19FeNb.

9. The improved design method for an electric wedge gate valve according to claim 1, characterized in that, The method further includes: Step S9: Obtain the verification result data of the prototype manufactured according to the improved design scheme output in step S8 in the verification test, and determine whether the verification result data meets the preset judgment conditions. If so, confirm that the improved design scheme meets the requirements.

10. The improved design method for an electric wedge gate valve according to claim 9, characterized in that, The verification tests include one or more of the following: mechanical calculations, simulation analysis, valve switching operation tests, locked-rotor tests, valve seat sealing tests, water pressure tests, circulation tests, thermal cycling tests, seismic performance tests, thermal shock tests, and high-energy pipeline fracture tests. When the verification test includes a stall test, the verification result data includes the deformation data of the valve stem after the stall test, and the preset judgment condition includes that the deformation data of the valve stem is less than or equal to the deformation threshold.

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