A method for measuring and calculating the clearance of the gland seal of a generator in a nuclear power plant

Abstract

The present invention relates to the technical field of nuclear power plant maintenance, and specifically discloses a method for measuring and calculating the gap of the generator sealing gland in a nuclear power plant, which includes the following steps: Step 1: Fabricate a jig and measure the outer diameter of the jig and the corresponding shaft diameter at the air side sealing gland ring; Step 2: Conduct a contact inspection on the air side sealing gland ring; Step 3: Measure and calculate the inner diameter of the air side sealing gland ring; Step 4: Introduce a temperature compensation value; Step 5: Measure and calculate the gap of the air side sealing gland ring; Step 6: Measure and calculate the gap of the hydrogen side sealing gland ring. In view of the actual situation that the material of the sealing gland is greatly affected by the ambient temperature, resulting in a large change in the gap, the present invention method introduces a temperature compensation value, which can eliminate the influence of the deformation of the sealing gland on the gap under different ambient temperatures, making the calculated value of the sealing gland gap more accurate.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear power plant maintenance, and particularly relates to a method for measuring and calculating the clearance of the sealing gland of a generator in a nuclear power plant. Background Art

[0002] In a nuclear power plant with a capacity of one million kilowatts, the generator, as an important device in the secondary loop, is responsible for converting the mechanical energy transmitted from the steam turbine into electrical energy and delivering it to the power grid. In the generators of Units 1-4 of a certain nuclear power plant, hydrogen cooling is adopted inside the generators. Sealing glands are provided at both ends of the generator rotor to seal the hydrogen inside the generator. The specific structure is shown in Figure 1 . Among them, the sealing gland mainly consists of a sealing seat 5, a hydrogen-side sealing gland ring 8, and an air-side sealing gland ring 9. The outer circle of the sealing seat is fastened to the end cover 4 with bolts 11 and positioned by a positioning pin, and a sealing strip 12 is provided on the fastening surface. The oil groove 6 on the inner circle of the sealing seat is used to place the hydrogen-side sealing gland ring 8 and the air-side sealing gland ring 9. Each side of the sealing gland ring is further divided into four sections of sealing gland blocks, which are connected end to end to form a ring. A baffle plate 13 is also provided on the hydrogen side of the sealing seat 5 and fixed with bolts 10. The spring 7 is located inside the oil groove 6, and the hydrogen-side sealing gland ring 8 and the air-side sealing gland ring 9 are fixed by tightening the spring 7. After the sealing oil is pumped into the oil groove 6 of the sealing seat, it flows through the clearance between the sealing gland rings and the radial clearance between the sealing gland rings and the rotor 3, and then flows out from two opposite directions along the axial direction of the rotor 3 respectively, forming a hydrogen-side oil flow 1 and an air-side oil flow 2. The oil flow plays a sealing role to ensure that the hydrogen inside the machine will not leak out and the air outside the machine will not enter the machine.

[0003] In the design, there are certain clearances between the hydrogen-side sealing gland ring 8, the air-side sealing gland ring 9 and the generator rotor 3 respectively. If the clearance is too large, it is easy to cause a decline in the sealing effect and hydrogen leakage. At the same time, it is also easy to cause an excessive flow rate of the pressure oil, resulting in the pressure oil entering the generator interior and affecting the insulation performance of the generator. If the clearance is too small, the cooling effect of the sealing gland is uneven, which is easy to cause damage to the sealing gland. At the same time, it is easy to cause rubbing between the sealing gland and the generator rotor, resulting in large vibrations of the unit and affecting the operation reliability of the generator. Therefore, during the major overhaul of the nuclear power plant, it is necessary to measure the clearance of the generator sealing gland and adjust it to the design range.

[0004] The conventional method for measuring the clearance of the gland seal is as follows: after the gland seal is reinstalled, the top of the gland seal ring falls on the oil groove of the gland seat by its own gravity. Clearances are formed between the upper and lower halves of the gland seal ring and the upper and lower halves of the rotor respectively. Then, a feeler gauge is used to measure the clearances between the gland seal ring and the upper and lower halves of the generator rotor respectively. The sum of the upper and lower clearances is the gland seal clearance. If it is unqualified, the gland seal needs to be removed again, and the clearance is adjusted by grinding the end face of the gland seal ring. This method requires rework, and the workload of clearance adjustment is large, which is likely to delay the on-site maintenance period. At the same time, since the material of this type of gland seal is copper, the copper material has a large deformation under the influence of temperature, and the required range of the gland seal clearance is small, which easily leads to inaccurate measurement of the gland seal clearance and the inability to guarantee the gland seal clearance. During the application process of a certain million-kilowatt nuclear power plant, an event occurred where the seal oil flow exceeded the standard due to an excessive gland seal clearance, which further led to oil ingress into the generator and a turbine trip, reducing the equipment reliability of the generator and affecting the safe and reliable operation of the system and the unit.

[0005] Therefore, designing a more reliable method for measuring and calculating the clearance of the gland seal of the generator in a nuclear power plant is crucial for the safe and reliable operation of the equipment and the unit. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for measuring and calculating the clearance of the gland seal of a generator in a nuclear power plant, which can accurately measure and calculate the clearance of the gland seal of the generator and meet the design requirements.

[0007] The technical solution of the present invention is as follows:

[0008] A method for measuring and calculating the clearance of the gland seal of a generator in a nuclear power plant includes the following steps:

[0009] Step 1: Fabricate a jig, and measure the outer diameter of the jig and the corresponding shaft diameter at the air-side gland seal ring

[0010] Fabricate a special measuring jig for the air-side gland seal ring, which is a stepped cylinder structure;

[0011] The outer diameter of the upper cylinder of the jig is larger than the inner diameter of the air-side gland seal ring, and the upper surface of the middle cylinder is matched with the lower surface of the air-side gland seal ring;

[0012] Measure the outer diameter of the upper cylinder of the measuring jig, denoted as a;

[0013] Measure the current ambient temperature, denoted as T, and require T ≤ 30°C;

[0014] Measure the outer diameter of the generator rotor corresponding to the air-side gland seal ring, denoted as D;

[0015] Step 2: Check the contact of the air-side gland seal ring

[0016] Apply the developer evenly on the surface of the upper cylinder of the jig. Connect the four segments of the air-side seal segments end to end to form an air-side seal ring and rub it back and forth against the jig. Determine the effective contact area between each segment of the air-side seal ring and the jig by checking the contaminated area of the developer on the air-side seal ring, and ensure that the contact area of each segment is not less than 75%;

[0017] Step 3: Measurement and calculation of the inner diameter of the air-side seal ring

[0018] Install the air-side seal segments on the jig to form an air-side seal ring. Use a clamp to make each segment of the air-side seal ring and the air-side seal ring and the jig fit tightly against each other. Denote the gap between the air-side seal ring and the jig as A, and the gaps between adjacent air-side seal segments as B, C, E, and F; and ensure that the gap values at A, B, E, and F do not exceed 0.02 mm, and there is no misalignment at the joint surface between the air-side seal segments;

[0019] Measure the gap at C, which is the difference between the inner circumference of the air-side seal ring and the outer circumference of the jig, denoted as b;

[0020] Calculate the difference between the outer diameter of the jig and the inner diameter of the air-side seal ring, denoted as c = b / π;

[0021] Calculate the actual inner diameter value of the air-side seal ring, denoted as d = a - c;

[0022] Step 4: Introduce the temperature compensation value

[0023] Refer to the "Temperature Compensation Value Curve Graph of the Seal Ring Gap", select the curve corresponding to the current ambient temperature T, and use the actual inner diameter value d of the air-side seal ring as the abscissa to find the value of the gap correction on the ordinate, that is, the temperature compensation value of the seal ring gap, denoted as e;

[0024] When the ambient temperature is 20 °C, theoretically the standard gap of the air-side seal ring is 0.04 - 0.08 mm;

[0025] Step 5: Measurement and calculation of the air-side seal ring gap

[0026] Calculate the air-side seal ring gap value f, f = d - e - D;

[0027] Compare it with the standard value of the air-side seal ring gap at 20 °C. If the gap value f is unqualified, repair or replace the air-side seal ring until the gap value f is qualified.

[0028] The measurement in Step 1 is carried out at the same time and the same place.

[0029] In Step 1, the jig is a three-step cylindrical structure, divided into an upper cylinder, a middle cylinder, and a lower cylinder.

[0030] If the effective contact area in Step 2 is unqualified, repair it. Use the scraping method to correct the geometric lines of the air-side seal ring to be qualified.

[0031] If it is necessary to scrape the air-side seal ring in Step 2, it must be scraped evenly across the entire circumference so that it is also a complete circle after scraping.

[0032] The described tooling, hydrogen-side seal ring, and air-side seal ring are all cleaned and kept clean.

[0033] It also includes Step 6, measurement and calculation of the hydrogen-side seal ring clearance:

[0034] Repeat Steps 1 to 5 to measure and calculate the hydrogen-side seal ring clearance; when the ambient temperature is 20°C, theoretically the standard for the hydrogen-side seal ring clearance is 0.11 - 0.15 mm; if the measurement result is unqualified, adjust it until it is qualified.

[0035] The remarkable effects of the present invention are as follows:

[0036] (1) The present invention designs a method for measuring and calculating the clearance of the generator seal ring in a nuclear power plant. During the overhaul stage of the seal ring, a special measurement tooling is made to replace the generator rotor, so as to measure and adjust the seal ring clearance in advance. On the premise of ensuring the measurement accuracy, the risk of rework is eliminated, and the overhaul quality and construction period are guaranteed.

[0037] (2) In view of the actual situation that the material of the seal ring is greatly affected by the ambient temperature, resulting in a large change in the clearance, the present invention introduces a temperature compensation value, which can eliminate the influence of the deformation of the seal ring at different ambient temperatures on the clearance, making the calculated value of the seal ring clearance more accurate.

[0038] (3) According to the method of the present invention, the clearance of the generator seal ring can be accurately measured and calculated to ensure meeting the design requirements. It has been experimentally applied many times to the overhaul of the generator seal rings of Units 1 - 4 of a million-kilowatt pressurized water reactor power station, completely solving the defect of large seal oil flow caused by the low measurement accuracy of the traditional method, achieving good results, and improving the operation reliability of the generator. Description of the Drawings

[0039] Figure 1 It is a schematic diagram of the seal ring structure;

[0040] Figure 2 It is a schematic diagram of the position of the seal ring clearance f;

[0041] Figure 3 It is a schematic diagram of the seal ring clearance measurement;

[0042] Figure 4 It is Figure 3 The schematic diagram in the G-G direction in

[0043] Figure 5 It is a curve graph of the temperature compensation value for the clearance of the sealing gland.

[0044] In the figure: 1 - hydrogen-side oil flow; 2 - air-side oil flow; 3 - rotor; 4 - end cover; 5 - sealing seat; 6 - oil sump; 7 - spring; 8 - hydrogen-side sealing gland ring; 9 - air-side sealing gland ring; 10 - oil baffle fastening bolt; 11 - sealing seat fastening bolt; 12 - sealing strip; 13 - oil baffle; 14 - tooling. Specific embodiments

[0045] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0046] A method for measuring and calculating the clearance of the sealing gland of a generator in a nuclear power plant. During the overhaul stage of the sealing gland, a special measuring tooling is made to replace the generator rotor, so as to measure the clearance of the sealing gland in advance and make adjustments. On the premise of ensuring the measurement accuracy, the risk of rework is eliminated, and the overhaul quality and construction period are guaranteed. The following takes the measurement and adjustment of the clearance of the air-side sealing gland ring as an example for illustration. Assume that the clearance value of the air-side sealing gland ring is f, and the position is as Figure 2 shown. The method includes the following steps:

[0047] Step 1: Make the tooling and measure the outer diameter of the tooling and the corresponding shaft diameter at the air-side sealing gland ring

[0048] Make a special measuring tooling 14 for the air-side sealing gland ring 9. The tooling 14 is a three-step cylindrical structure, divided into an upper cylinder, a middle cylinder and a lower cylinder;

[0049] As Figure 3 , 4 shown, the outer diameter of the upper cylinder of the tooling 14 is larger than the inner diameter of the air-side sealing gland ring 9, and the upper surface of the middle cylinder is matched with the lower surface of the air-side sealing gland ring 9;

[0050] Measure the outer diameter of the upper cylinder of the measuring tooling 14, denoted as a;

[0051] Measure the current ambient temperature, denoted as T, and require T ≤ 30°C;

[0052] Measure the outer diameter of the generator rotor corresponding to the air-side sealing gland ring 9, denoted as D;

[0053] The above measurements are carried out at the same time and the same place to avoid large errors caused by excessive environmental temperature differences;

[0054] Step 2: Check the contact of the air-side sealing gland ring

[0055] Apply a developer such as red lead powder evenly on the surface of the upper cylinder of the jig 14. Connect the four segments of the air-side sealing tile end to end to form an air-side sealing tile ring 9 and rub it back and forth against the jig 14. Determine the effective contact area between each segment of the air-side sealing tile ring 9 and the jig 14 by checking the contaminated area of the red lead powder on the air-side sealing tile ring 9, and ensure that the contact area of each segment is not less than 75%;

[0056] If it is unqualified, repair it. Use the scraping method to correct the geometric line of the air-side sealing tile ring 9 to be qualified; if the air-side sealing tile ring 9 needs to be scraped, it must be scraped evenly throughout the circumference so that it is also a complete circle after scraping;

[0057] Step 3: Measurement and calculation of the inner diameter of the air-side sealing tile ring

[0058] Install the air-side sealing tiles on the jig 14 to form the air-side sealing tile ring 9. Use a clamp to make each segment of the air-side sealing tile ring 9 and the air-side sealing tile ring 9 and the jig 14 fit tightly against each other. Denote the gap between the air-side sealing tile ring 9 and the jig 14 as A, and the gaps between adjacent air-side sealing tiles as B, C, E, and F; and ensure that the gap values at A, B, E, and F do not exceed 0.02 mm, and there is no misalignment at the joint surface between the air-side sealing tiles;

[0059] Measure the gap at C, which is the difference between the inner circumference of the air-side sealing tile ring 9 and the outer circumference of the jig 14, and denote it as b;

[0060] Calculate the difference between the outer diameter of the jig 14 and the inner diameter of the air-side sealing tile ring 9, and denote it as c = b / π;

[0061] Calculate the actual inner diameter value of the air-side sealing tile ring 9, and denote it as d = a - c;

[0062] Step 4: Introduce the temperature compensation value

[0063] Refer to Figure 5 "Sealing Tile Gap Temperature Compensation Value Curve Graph", select the curve corresponding to the current ambient temperature T. Using the actual inner diameter value d of the air-side sealing tile ring 9 as the abscissa, find the gap correction value relative to 20°C on the ordinate, that is, the sealing tile gap temperature compensation value, and denote it as e;

[0064] When the ambient temperature is 20°C, the theoretical gap standard for the air-side sealing tile ring 9 is 0.04 - 0.08 mm;

[0065] Step 5: Measurement and calculation of the air-side sealing tile ring gap

[0066] Calculate the air-side sealing tile ring gap value f, f = d - e - D;

[0067] Compare with the standard value of the clearance between the air-side sealing gland ring 9 at 20°C. If the clearance value f is unqualified, repair or replace the air-side sealing gland ring 9 until the clearance value f is qualified;

[0068] Step 6: Measurement and calculation of the clearance of the hydrogen-side sealing gland ring

[0069] Repeat Steps 1-5 to measure and calculate the clearance of the hydrogen-side sealing gland ring 8. When the ambient temperature is 20°C, the theoretical standard clearance of the hydrogen-side sealing gland ring 8 is 0.11-0.15 mm. If the measurement result is unqualified, adjust it until it is qualified.

[0070] Components such as the tooling 14, hydrogen-side sealing gland ring 8, and air-side sealing gland ring 9 should be cleaned and kept clean to avoid inaccurate measurement data.

[0071] Embodiment

[0072] Taking the measurement and calculation of the clearance of the hydrogen-side sealing gland ring in a certain instance as an example, the specific implementation method is described as follows:

[0073] Step 1: Measure the shaft diameter and the outer diameter of the tooling

[0074] Measure the outer diameter of the sealing gland ring tooling a = 800.11 mm;

[0075] Measure the current ambient temperature T = 23°C;

[0076] Measure the outer diameter of the rotor journal D = 799.96 mm corresponding to the sealing gland ring part;

[0077] Step 2: Contact inspection of the hydrogen-side sealing gland ring

[0078] Evenly apply red lead powder on the surface of the sealing gland ring measuring tooling, and rub the sealing gland ring section against the tooling to check the effective contact area between each section of the sealing gland and the tooling. The contact area meets the requirement of ≥75%;

[0079] Step 3: Measurement and calculation of the inner diameter of the hydrogen-side sealing gland ring

[0080] Assemble each section of the sealing gland ring on the sealing gland ring measuring tooling, and use a special clamp to make each section of the sealing gland ring, the sealing gland ring and the tooling fit tightly to ensure that the clearance values at A, B, E, and F are <0.02 mm;

[0081] Measure the clearance at C as the difference b between the inner circumference of the sealing gland ring and the outer circumference of the tooling, b = 0.04 mm;

[0082] The difference c between the outer diameter of the tooling and the inner diameter of the sealing gland ring = b / π = 0.013 mm;

[0083] The actual inner diameter value d of the sealing gland ring = a - c = 800.11 mm - 0.013 mm = 800.097 mm;

[0084] Step 4: Introduce the temperature compensation value

[0085] Refer to the appendix Figure 5 , find the curve corresponding to the current ambient temperature T, which is 23°C. With the actual inner diameter value d of the sealing gland as the abscissa, find the ordinate value, which is the temperature compensation value e of the sealing gland clearance, and e = 0.017 mm;

[0086] Step 5: Measurement and calculation of the hydrogen-side sealing gland ring clearance

[0087] The sealing gland clearance value f = d - e - D = 800.097 - 0.017 - 799.96 = 0.12 mm, which meets the hydrogen-side sealing gland ring clearance standard of 0.11 - 0.15 mm at 20°C. Therefore, the hydrogen-side sealing gland ring clearance of this sealing gland is qualified.

[0088] The above shows and describes the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0089] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for measuring and calculating the clearance of the sealing gland of a generator in a nuclear power plant, characterized in that: It includes the following steps: Step 1: Manufacture a jig, and measure the outer diameter of the jig and the corresponding shaft diameter at the air-side sealing gland ring; Manufacture a special measuring jig for the air-side sealing gland ring, which is a stepped cylinder structure; The outer diameter of the upper cylinder of the jig is larger than the inner diameter of the air-side sealing gland ring, and the upper surface of the middle cylinder fits with the lower surface of the air-side sealing gland ring; Measure the outer diameter of the upper cylinder of the measuring jig, denoted as a; Measure the current ambient temperature, denoted as T, and require T ≤ 30°C; Measure the outer diameter of the generator rotor corresponding to the air-side sealing gland ring, denoted as D; Step 2: Check the contact of the air-side sealing gland ring; Evenly apply a developer on the surface of the upper cylinder of the jig. Connect the four air-side sealing gland blocks end to end to form an air-side sealing gland ring and rub it against the jig back and forth. Judge the effective contact area between each section of the air-side sealing gland ring and the jig by checking the contaminated area of the developer on the air-side sealing gland ring, and ensure that the contact area of each section is not less than 75%; Step 3: Measure and calculate the inner diameter of the air-side sealing gland ring; Install the air-side sealing gland blocks on the jig to form an air-side sealing gland ring. Use a clamp to make the sections of the air-side sealing gland ring and the air-side sealing gland ring and the jig fit tightly with each other. Denote the clearance between the air-side sealing gland ring and the jig as A, and denote the clearances between adjacent air-side sealing gland blocks as B, C, E, F; and ensure that the clearance values at A, B, E, F do not exceed 0.02 mm, and there is no misalignment at the joint surface between the air-side sealing gland blocks; Measure the clearance at C, which is used as the difference between the inner circumference of the air-side sealing gland ring and the outer circumference of the jig, denoted as b; Calculate the difference between the outer diameter of the jig and the inner diameter of the air-side sealing gland ring, denoted as c = b / π; Calculate the actual inner diameter value of the air-side sealing gland ring, denoted as d = a - c; Step 4: Introduce the temperature compensation value; Define a temperature compensation value curve graph for the sealing gland clearance. The horizontal axis of the temperature compensation value curve graph for the sealing gland clearance is the sealing gland diameter, with the unit of mm, and the vertical axis is the sealing gland clearance compensation value, with the unit of mm; at this time, referring to the temperature compensation value curve graph for the sealing gland clearance, select the curve corresponding to the current ambient temperature T. Using the actual inner diameter value d of the air-side sealing gland ring as the abscissa, find the numerical value of the ordinate clearance correction, that is, the sealing gland clearance temperature compensation value, denoted as e; When the ambient temperature is 20°C, theoretically, the standard clearance of the air-side sealing gland ring is 0.04 - 0.08 mm; Step 5: Measure and calculate the clearance of the air-side sealing gland ring; Calculate the clearance value f of the air-side sealing gland ring, f = d - e - D; Compare it with the standard clearance value of the air-side sealing gland ring at 20°C. If the clearance value f is unqualified, repair or replace the air-side sealing gland ring until the clearance value f is qualified.

2. A method for measuring and calculating the clearance of the sealing gland of a generator in a nuclear power plant as described in claim 1, characterized in that: The measurement in Step 1 is carried out at the same time and the same place.

3. A method for measuring and calculating the clearance of the sealing gland of a generator in a nuclear power plant as described in claim 1, characterized in that: In Step 1, the jig is a three-step cylinder structure, which is divided into an upper cylinder, a middle cylinder and a lower cylinder.

4. A method for measuring and calculating the clearance of the generator sealing gland in a nuclear power plant as described in claim 1, characterized in that: If the effective contact area in step 2 is unqualified, repair is carried out, and the geometric line of the air-side sealing gland ring is corrected to be qualified by using the scraping method.

5. A method for measuring and calculating the clearance of the generator sealing gland in a nuclear power plant as described in claim 4, characterized in that: If the air-side sealing gland ring needs to be scraped in step 2, it must be scraped evenly over the entire circumference so that it is also a complete circle after scraping.

6. A method for measuring and calculating the clearance of the generator sealing gland in a nuclear power plant as described in any one of claims 1 to 5, characterized in that: It further includes step 6, measuring and calculating the clearance of the hydrogen-side sealing gland ring: Repeat steps 1 to 5 to measure and calculate the clearance of the hydrogen-side sealing gland ring; when the ambient temperature is 20 °C, the theoretical standard for the clearance of the hydrogen-side sealing gland ring is 0.11 - 0.15 mm; if the measurement result is unqualified, adjust it until it is qualified.

7. A method for measuring and calculating the clearance of the generator sealing gland in a nuclear power plant as described in claim 6, characterized in that: The fixture, the hydrogen-side sealing gland ring, and the air-side sealing gland ring are all cleaned and kept clean.

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